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Non Life Sciences => Technology => Topic started by: Professor Mega-Mind on 28/09/2018 05:14:17

Title: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 28/09/2018 05:14:17
       Heavier than air Airships
 Are these a good idea ?  It is hereby put forth that they are .  Slightly heavier than air , lifting-body airships could be extremely fuel efficient , extremely quiet & comfortable , extremely controll-able , extremely safe , and extremely convenient as well .  The very-low thrust requirement means that extremely efficient , alternative fuel drivetrains can be used . Traveling directly from city-core to city-core would become entirely practical , as would close-up , directly over-head eco-tourism .  Both mech-anical malfunction , and terror-strike , would be greatly reduced in terms of the danger they posed to the passengers & crew of these craft .  Their physical performance , and avionics , would be good enough to keep them well away from any bad weather that might head their way .  Travel times would be comparable to those for general aviation , or helicopters . 
Overall , modern technology ensures that these airships would realize the potential that their 20th century predecessors evidenced so long ago .
The preposition here is that changing societal needs call for changing technological archi-tectures and paradigms .  HTA. airships could fulfill many 21st century needs beautifully . 
That's all for now , folks !...P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Kryptid on 28/09/2018 06:04:15
You're not the only one who thinks they are a good idea: https://inhabitat.com/the-dynalifter-could-transport-160-tons-of-freight-using-less-fuel-and-money-than-a-jet/
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 28/09/2018 06:18:05
                       Airships
Riddle me this:Would a flying-wing version , with a more airplane-like construction and performance , be a worthy idea also ?.....P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: syhprum on 28/09/2018 08:57:49
The Hindenburg was a success comparable to the Concord creaming off wealthy customers who wanted more speed and comfort than the liners would provide.
Unfortunately the use of Hydrogen as Helium was not available turned what may well have been a relatively minor incident into a spectacular fire (although half the passengers survived) that led to its successors being scrapped at the start of WWII. 
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 28/09/2018 09:05:42
 You are one right syprum-dude !
What would you rather be on when the Mad-Bomber strikes ?  Me , I'd rather sink back to Earth , than auger in !.....P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 28/09/2018 18:04:10
Analysis of the Hindenburg fire shows the problem was more the fault of the aluminum-impregnated fabric than the hydrogen fill.

The "Flying Bottom" is a regular sight around here, though it spent more time on the ground than in the air recently. Definitely has potential.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 28/09/2018 18:24:58
 Kind of resembles NASA's recent
" Double Bubble " design , eh ?
 Interesting that when the Akron & Macon went down , the initial crashes were non-fatal .......P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Supervolant on 07/10/2018 14:24:39
I hope so...

I would love to see them again. I especially like the heavier-than-air approach making them less prone to wind sheer as these flying giants were really dependent on good weather. These airships filled with a lighter then air gas would be really expensive tough.. Hydrogen is a huge Nono... no matter then safety precautions no-one does wan't so see something flying again what essentially is a flying bomb. Helium is good enough and offers just marginal less lift. But one has to count in that Helium is a very finite resource dependent on radio active alpha decay which needs millions over millions of years to be created in useful ammounts! Our Helium is about to come to an end and we need it more for clinical and industrial use cases then we do so for something flying. (tough I love everything flying). Tough I do believe that helium asteroid / moon mining becomes a thing before we run out of it.

Let's put the scarcity of Helium aside for a moment. Let's see the lifting power of a 100 meter diameter spherical balloon.

Sphere Volume = 4/3 x Pi x r3

= 4/3 x Pi x 50m3

= 4/3 x Pi x 125000

Sphere Volume = 523.598,78 m3

1m3 of Helium Lifts about 1,11 kg

523.598,78 m3 x 1,11kg = 581.194,64 kg

This quick calculation shows a 100m diameter spherical balloon can lift 581 tons. Thats the very extreme dry weight of course! One has to subtract any weight used for construction.  To comparison: A Containership usually carries around 1000 containers filled with 15.000 - 18.000 tons. The largest ones are able to carry up to 25.000 tons!

Even tough our Airship would only be able to carry a very marginal amount of something in comparison to our naval brothers the Airship would be about +3 times faster and can overfly water and land. Directly leave cargo where it's needed, a huge logistical win!

For cargo a good Idea? I actually believe yes! We could even build way larger Airships making them even more commercial. And such a large Airship delivers more then enough space for solar cells. Flying over the clouds with near maximum sun irradiation one would be completely self sustaining!

Also a good Idea for people? Not so much.. Way too slow. One can easily travel by plane and is +20 times faster then one inside an Airship no matter how innovative the propulsion system. A huge Airship has literally tons of drag one has to overcome in the first place.

But for the super rich? Well multi billion dollar yachts are a thing, so why not flying ones? I would certainly buy a flying mansion if I would have the money. A wonder none have been made yet. I have to do some other stuff beforehand but in some years from now I will take this challenge on for sure! (actually the reason why I answer on this topic, as this is cargo and yacht airship topic is of extreme interest to me)
Imagine a flying mansion with your private rooftop VTOL Aircraft Landing place... one would be a true citizen of the world!

Modify:

Now to your heavier-than-air approach. Just realized something. I wan't to give you credit for "solving" a huge problem in airship design. Counter balancing is the keyword. Whenever a passenger steps inside an airship it usually drops blast in the shape of water being thrown out. This counter balancing makes airships extremely unhandy... But when one builds an airship so it's perfectly balanced with and without payload the airship would rely solely on it's propulsion system and way less on it's lifting gas. I put "solving" in quotes because the problem has just been stated, now one has to come up with a technical solution in order to really solve it. Takes some time for me but I will find it.... Thank you.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 07/10/2018 14:39:53
If the wind is in the wrong direction they become hugely inefficient because they present a massive cross section.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 07/10/2018 17:45:23
To : Supervolant
Glad you see the advantages of a heavier-than-air airship .  I figure steerable , contra-rotating , ducted , turboprop engines , combined with a streamlined lifting-body shape , would allow for jet-class altitudes with turboprop-class speeds .  No need to vent , compress , or dump anything .  Just have enough thrust for VTOL capability at max. TOW .
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 07/10/2018 17:49:48
Just have enough thrust for VTOL capability at max. TOW .

That'll; be fun when it's windy.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Supervolant on 07/10/2018 18:12:08
Just have enough thrust for VTOL capability at max. TOW .

That'll; be fun when it's windy.

@Bored chemist I believe what Professor Mega-Mind is talking about are rigid body - rigid shell airships, thats why the term heavier then air in contrast to lighter then air airship comes up. These airships in comparison to soft body - soft shell "blimps" can be designed to be structurally sound while giving sheer winds less aerodynamic resistance then current and old age airship designs. I believe a saucer shape to be one good design since it would have ist major surface area up and down. VTOL - Tech can balance up and down moving air streams but most of the weather comes from the side where the overall surface area of a saucer shape would give the wind less surface area to attack on. Making the ride in fact fun.

People inside the Hindenburg were capable of balancing a pen horizontal for hours (in standard weather conditions). Airships are incredibly stable and vibration free.

_

@Professor Mega-Mind I am all in for revolutionary technologies setting new benchmarks for whole industries. Do you have made any construction plans or at least sketches? Would love to see them.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 07/10/2018 18:25:30
I have had them on my internal blackboard for several years , however , there are several lifting-body designs out their that would approximate these .  Try sizing up the later flying-wing designs .  Also the various Airfish , and even Flying Flapjack designs are good starting points .  In the end , form follows function .
......... P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 07/10/2018 18:30:26
The point of the gas bag bit is to reduce TOW.
So, if that works properly TOW will be small (in principle, you can have it negative with the engines holding the ship down when you need to land)
And if you then say "Just have enough thrust for VTOL capability at max. TOW ."
you have specified that you want very little thrust.

With the best possible profile- and saucer shaped might be a good choice- you still have a craft with a large drag.
So, in all but the lightest wind, the thing will go whichever way the wind blows.

Essentially Professor Mega-Mind hasn't realised that TOW isn't the thing you use when you want to establish the thrust you need.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 07/10/2018 18:56:09
Think flying saucer , as in the Jupiter 2 .  Cross-wind have minimal effect .  The is at 30% weight with helium at sea-level .  Vectored thrust is strong enough , but not gas-guzzling .  Exhaust velocity is surprisingly high , as is fuel economy .  Safety is incredible , as is mission flexibility .
Of course the parameters are fully adjustable .
.....P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 07/10/2018 20:00:36
Think flying saucer , as in the Jupiter 2
Were you expecting to be taken seriously?
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 07/10/2018 22:38:36
Hey , flying-saucers have their strong points !
......P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 07/10/2018 23:14:06
The fuel efficiency of airships is partly due to their low speed, since drag increases with the square of indicated airspeed. If the only competition is a ship, then the airship in general has an advantage with an airspeed of up to 100 kt over long distances, but a headwind will directly reduce groundspeed whilst a large surface ship can proceed at 20 kt under almost any conditions and can thus provide a more reliable scheduled service.

Matters are slightly complicated by passenger comfort considerations. 100 kt from surface to cloud base can be very rough, but once you get above cloud the wind speed increases significantly and you can be flying backwards at 15,000ft in the UK. Climbing and descending through active cloud requires a certain determination in any machine, and nerves of steel if the beast is only marginally denser than air.

However if you are looking for adventure, want to loiter over a target, or need to deliver something to the middle of nowhere and beyond the range of a helicopter, the HTA airship has a lot going for it.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 09/10/2018 21:41:16
............Boeing X-48C  BWB
Take this concept craft , enlarge it to 300' by 300' .  Thicken it significantly , install permanent helium chambers to reduce MTOW to 200 klbs.  Have 4 rotatable contra-rotating hi-perf. ducted turboprop disk assemblies w/internal gas turbines , and external free turbine drives , providing 300 klbs. of static thrust , mounted quadrilaterally about the aircraft .  Make the craft's surface completely rigid-shell , and designed for 400+ mph at altitude .  Include tie-down capability for extreme weather .  Such an aircraft would provide the capabilities of both airplanes & helicopters , while having the fuel efficiency of an airship .  This craft would be highly resistant to bomb or missile , and extremely unlikely to actually crash .
Overall , the combination of HTA & Rigid Shell design would add new abilities , and safety factors , to an increasingly challenged aeronautical industry .
..........P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 09/10/2018 22:20:45
OK let's do a  "back of an envelope" calculation.
It's roughly 100m by 100m; that's 10,000 square metres*
And you are talking about 300,000 Lbs of thrust
That's about 150 tonnes or 1.5MN
About 150N/ m^2

And, according to this
https://www.engineeringtoolbox.com/wind-load-d_1775.html
that's the wind loading at about 16 m/s which is about 35mph.

If you have a headwind of more than 35 mph your invention goes backwards.

Did you not believe me earlier?

* yes, I know- but if you make balloons that aren't fairly near spherical, they have too much area (and thus weight) for their volume, and they don't fly
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 10/10/2018 01:57:19
...............XF-5U vs Spitfire
Let us compare one of the best fighter aircraft of WW2 to an aircraft reasonably similar to what I am proposing . 
Sup.Mar.Spitfire had a high-aspect ratio elliptical wing mounted on a tube- body .  Power/weight was excellent for it's type .  Propellers were optimized for high speed , as was the body .
Vought XF-5U : Thick elliptical-wing lifting-body w/outboard engines .  Power/weight significantly lower than Spitfire .  Propellers optimized for VSTOL , as was body .
Despite the above design disadvantages , the XF-5U still had much greater range , and a 70 mph higher top-speed .  It was also far stronger structurally .  It actually required a construction wrecking-ball to break it up for scrap .
A disk-shaped craft is not as subject to side-winds as a slab-side , like an airship or a tube .  The low weight would greatly reduce induced-drag .  The outboard propulsor placement would negate wing-tip vortice drag .  The aircraft coefficient of drag would be comparable to the proposed Boeing super-jumbo BWB ; a 500 to 600 mph. thick lifting body with a much lower power/weight ratio .  This VTOL craft would not even need wheel assemblies , just light-weight , compact , retractable skids .  Controllability upon landing would be excellent , due to the vectorable thrust .  Ditto takeoff .
All in all , a craft like we've never seen .  A combination of capabilities previously unimagined .  All we need do is ignore the "smoke & veils" naysayers , and make reasonable extrapolations .  Then we are golden !
.......P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Supervolant on 14/10/2018 09:05:14
@Professor Mega-Mind, I believe in the concept. Am working inside an German E-VTOL Company right now, we wan't to get things done here...  You might wan't to send me a personal message with your contact details and we get to talk about this in a rather constructive manner?

Looking ahead to the future,
- Robert
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 14/10/2018 09:25:39
A disk-shaped craft is not as subject to side-winds as a slab-side , like an airship or a tube .
All aircraft are equally susceptible to crosswind in flight. You fly through a "box of air", and if the box is moving sideways or backwards in relation to your intended track, you have to go faster and change course to compensate. It's not the same as crosswind on the ground, which has the same effect as on a car or boat - you weathercock into wind depending on the shape of the vehicle and the position of its wheels or keel.

Obviously the effect is less significant at higher airspeeds, but the increase of windspeed with altitude means that even at 500 kt you need to correct for wind drift and going backwards at 150 kt and 30,000 ft is one of the joys of propeller aircraft.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 14/10/2018 09:29:02
All we need do is ... make reasonable extrapolations
Go on then.
Make some reasonable assumptions, rather than imagining that you can magic any problems away.

I'm the one using maths- you are the one trying to hide behind smoke and mirrors.

The low weight would greatly reduce induced-drag . 

That's just silly. weight doesn't influence drag.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 14/10/2018 12:58:09
...........Aircraft Drag Factors
FoilSimIIIJavaApplet
NASA Glenn Research Center
 This is where you will find you #s regarding aircraft weight and wing loading effects .
 Rest assured , weight affects aircraft performance in a manner similar to watercraft .
 In regards to crosswinds , I was specifically referring to those occurring while the aircraft is on the ground .  This has always been an issue for airships .  The Form Drag ( cd ) involved is much lower for a rounded , elliptical disc subjected to side-wind , than for a giant tube subjected to same .  Friction drag is a seperate issue , but I will say that the amount of surface area per square foot of internal space would be significantly less than a standard tube & wing of similar volume .  This helps greatly with a craft that would contain a huge chamber of lifting gas .  The frontal form-drag would be comparable to the fuselage section of a B-2 bomber , with a similar 20% height/length ratio .
Lastly , I will say that landing in crosswinds would be safer than normal aircraft , as thrust-vectoring  is built into the design .
Alright , Bored One , can you hear me now ?
........P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 14/10/2018 13:10:59
Rest assured , weight affects aircraft performance in a manner similar to watercraft .
That's just silly. weight doesn't influence drag.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 14/10/2018 13:42:10
.................Induced Drag
B.C. : Try Aviation Stack Exchange .
Go on , don't be shy .  They're all about the numbers and formulas , good explanations too. 
Okay , don't say I never did nuthin' for ya !
........P.M. 
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 14/10/2018 14:26:06
Induced drag is not a function of weight.

Crosswind takeoff and landing is not a problem if you have  a vertical thrust vector - you just point the aircraft into wind and land vertically with zero groundspeed - i.e no crosswind.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 14/10/2018 14:30:47
......................E-VTOL
Mr. Supervolant , I do not pretend to be an aerospace engineer , or even a professional .  I'm simply an enthusiast , with an eye for design .  That said , I can give you a bit of feedback and insight where your project is concerned .  I've got enough creativity to come up with some serious mess !
..........P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 14/10/2018 14:35:26
Wi-ke-pe-dia , Google it !
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Kryptid on 14/10/2018 17:38:51
weight doesn't influence drag.

I thought that for a while too, but then I was corrected by someone on another forum. Take an aircraft like an F-15, for example. Compare that F-15 when it is full of fuel to when it is at half fuel. You want to fly it at the same speed and altitude in both conditions. Since it is heavier when it is full, it needs to produce more lift than when it has less fuel. In order to produce more lift without changing speed or altitude, it needs to increase its angle of attack slightly. That increase in angle of attack increases its drag slightly. The difference in pressure between the upper surface and lower surface of the wing is now higher, increasing the strength of the wing-tip vortices and thus producing more total drag.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 14/10/2018 18:01:02
OK, everything influences drag.
You can "blame" the weight or you can blame the speed or whatever.
You want to fly it at the same speed and altitude in both conditions.
I might not...
The same speed makes life easier (though it's not an absolute requirement, planes vary airspeed to maintain teh same ground-speed if they want to reach their destination at a fixed time)  but altitude is a bit more  variable. Especially when the lift "balloon" depends depends on altitude.

The point about this hybrid is that the weight is "small" because it floats.
But the weight has to stay largely constant (laden or not) to maintain near neutral buoyancy or whatever (It would have to dump ballast when it took on passengers).

You raise an interesting point about the change in load due to burning fuel. It's hard to see how they could compensate for that.

And We are still waiting for any sensible figures on the more conventional drag- you push the thing through the air, so you have to push that air out of the way.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Kryptid on 14/10/2018 23:05:20
OK, everything influences drag.
You can "blame" the weight or you can blame the speed or whatever.
You want to fly it at the same speed and altitude in both conditions.
I might not...
The same speed makes life easier (though it's not an absolute requirement, planes vary airspeed to maintain teh same ground-speed if they want to reach their destination at a fixed time)  but altitude is a bit more  variable. Especially when the lift "balloon" depends depends on altitude.

The point about this hybrid is that the weight is "small" because it floats.
But the weight has to stay largely constant (laden or not) to maintain near neutral buoyancy or whatever (It would have to dump ballast when it took on passengers).

You raise an interesting point about the change in load due to burning fuel. It's hard to see how they could compensate for that.

And We are still waiting for any sensible figures on the more conventional drag- you push the thing through the air, so you have to push that air out of the way.


Oh don't get me wrong. I'm not saying that Professor Mega-Mind's concept here is realistic. Wanting a 300-foot rigid airship to travel above 400 miles per hour is pretty crazy.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 15/10/2018 00:39:57
You both have good points , buut...
The craft would have a fixed gas-chamber volume ; never changed & no ballast .  It's effective MTOW would be set permanently at perhaps 30% .  The planform would  be a reinforced rigid-shell , similar to a section of wing .  The shape & cd. would be reminiscent of a B-2 mid-section .  Given 4 A-380 class propulsors , the craft should achieve jumbo-like performance at all altitudes .  I will grant you , gas lift will decrease at higher altitudes  , but greater lifting surface will reduce wing-loading , thus reducing induced drag .  Friction-drag will be minimized at very high altitudes .  Size would be variable , but all would be capable of over 500 mph .  The craft would be fundamentally stable , like a paper airplane .  This would ensure that in case of power loss , the craft would slowly glide back to earth .
Alright , they live !........P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Kryptid on 15/10/2018 01:44:13
Given 4 A-380 class propulsors , the craft should achieve jumbo-like performance at all altitudes .

There is no way that is true. You want to take an X-48C, enlarge it so that it has a wingspan of 300 feet and then "thicken it significantly". Such an aircraft would have much, much more drag than an A380 because it would have a significantly thicker cross-sectional area. Since you want to give it four engines comparable to those on the A380, that by definition means that it is going to accelerate and fly much, much more slowly as well.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 15/10/2018 02:31:48
150k.lbs thrust each .  GE-90s could presently be modified from their current 130k.lbs .
Also , size could be adjusted if necessary .
Lastly , a top speed above 500 mph would suffice .
P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Kryptid on 15/10/2018 03:12:54
150k.lbs thrust each .  GE-90s could presently be modified from their current 130k.lbs .
Also , size could be adjusted if necessary .
Lastly , a top speed above 500 mph would suffice .
P.

With a specific fuel consumption of 0.545 pounds per pound of thrust per hour during cruising flight, four GE90 engines at 150,000 pounds of thrust each will consume 327,000 pounds of fuel during an hour's flight. Compare that with four Trents at 80,000 pounds that power the A380 (with a fuel consumption of 0.557 - 0.565 lb/lb f/h), which consume 178,240 - 180,800 pounds of fuel per hour. So your aircraft is 81 - 83% more fuel-thirsty than an A380.

However, unlike an A380, you are trying to get significant lift from lifting gas. This means that you have to minimize the total weight of the aircraft, which in turn means minimizing the total fuel capacity. More fuel means more weight, so too much fuel means you can't fly. Since the A380 doesn't have that limitation, it can carry much more fuel than your design. So your design consumes fuel almost twice as fast as an A380 while also not being able to carry as much of it. So it will have a much shorter range. Making the aircraft smaller in order to reduce drag will only make that problem worse.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 15/10/2018 03:58:36
..................Catch-a-22 !
Go 'head wit ya bad sehf !
I won't be trying to get gas lift , I will be getting gas lift , tons of it . Even with a top-half of helium , this craft will have enormous pax. and cargo capacity .  It will fly very efficiently , easily carrying 2X pax , cargo , and fuel .  The lower insurance costs , lesser planform maintenance costs , and VTOL capability will make it cheaper to fly , and super convenient  ( think city-center to city-center ) . Overall , a huge win-win !
And they liiive !
...........P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Kryptid on 15/10/2018 04:18:22
It will fly very efficiently

Not if it's a 300-foot airship travelling above 500 miles per hour, it won't. I've already pointed out that you'd be consuming huge amounts of fuel to produce the thrust needed to achieve something like that. Honestly, I'm doubtful that 4 engines producing 150,000 pounds of thrust each would even be enough to reach that speed: the cross-sectional area of your craft is enormous.
Title: Re: Are heavier-than-air hybrid airships a good idea?that weight doesn't influen
Post by: alancalverd on 15/10/2018 09:03:28
It's a good exercise to calculate the minimum size of a beer can (0.15 mm aluminum) that can lift itself if filled with hydrogen, then extrapolate to a useful load carrier. Some years ago I sketched a rigidised aluminum blimp with aerodynamic (i.e. thin) wings that looked rather like a Beluga. Halfway through the calculations, my date walked out of the bar, but I still think it's an interesting idea.

Every aspect of every aircraft is a compromise, which is why there are so many different species of birds. We could talk round in circles unless someone specifies a primary mission: load lifting, VTOL, efficient cruise, whatever....

BC is right that weight doesn't influence drag for a near-buoyant craft, since W ≈ 0. You can maintain altitude as you burn fuel by displacing your lift gas with air, just like a Zeppelin, or by deriving some lift from hot air which you allow to cool as you lose weight.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 15/10/2018 18:03:57
      ......  ..VTOL vs Airship
Analysts !  I'm sure , by now , that you see the two paths .  One pure engine , one Hybrid Airship .  The proposal here Is an all-engine , double-decker , lift-body craft,
 equivalent in dimension to two C-5 class fuselages set side-by-side .  Four internal GE-4 type 60klb thrust turbojet cores will power 4 contra-rotation , fully-vectorable , double-disk GE-90 propulsors .  Each propulsor will produce at least 300klb. of thrust , with each exhaust line having anti-cone block valves , and emergency thrust nozzles .  The craft would be of lighter construction than C-5 , but over 2.5 times the total floor space (including top floor) .  It's hold would be taller , and over twice as wide as C-5 .  It could easily transport 1,000 troops plus gear , and VTOL them into the most remote and inaccessible locations.  Turn-around time would be minimized , as runways would not even be involved .  Each engine core would lie in it's own protective  V-trough , to deflect any projectIles lucky enough to strike it .  These could be accessed internally by the crew during operations .  These systems would be quick-disconnect and modular .  Redundancy would be mandatory .  The pilot would have a highly capable digital assistant , capable of auto-pilot when needed . 
All good for the plane , add 1mcft. of helium , and you have your tank-lifter .
Okay , critiques please !
..........P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 15/10/2018 19:48:41
      ......  ..VTOL vs Airship
Analysts !  I'm sure , by now , that you see the two paths .  One pure engine , one Hybrid Airship .  The proposal here Is an all-engine , double-decker , lift-body craft,
 equivalent in dimension to two C-5 class fuselages set side-by-side .  Four internal GE-4 type 60klb thrust turbojet cores will power 4 contra-rotation , fully-vectorable , double-disk GE-90 propulsors .  Each propulsor will produce at least 300klb. of thrust , with each exhaust line having anti-cone block valves , and emergency thrust nozzles .  The craft would be of lighter construction than C-5 , but over 2.5 times the total floor space (including top floor) .  It's hold would be taller , and over twice as wide as C-5 .  It could easily transport 1,000 troops plus gear , and VTOL them into the most remote and inaccessible locations.  Turn-around time would be minimized , as runways would not even be involved .  Each engine core would lie in it's own protective  V-trough , to deflect any projectIles lucky enough to strike it .  These could be accessed internally by the crew during operations .  These systems would be quick-disconnect and modular .  Redundancy would be mandatory .  The pilot would have a highly capable digital assistant , capable of auto-pilot when needed . 
All good for the plane , add 1mcft. of helium , and you have your tank-lifter .
Okay , critiques please !
..........P.M.
Never mind the petty details like contra rotating props.
Calculate the cross sectional area that you have to push through the air.

Let's go with Alan's beer can.
0.15mm Al sheet.
Let's turn it into a tube an consider a 1 metre length
Circumference is 3.14 metres, thickness 0.00015 metres length 1 metre so the volume is
3.14 * 0.00015 *1
That's 0.000471 cubic meters
Or 0.471 litres which, at a density of about 2.7 Kg/litre gives us a mass of 1.2717 Kg, which is roughly the mass of a cubic metre of air.
And the volume of the big beer can is about pi/4 cubic metres.
So, even something as flimsy as a shell made from a beer can isn't light enough to float in air (and that's ignoring the mass of the ends of the cylinder and the mass of the helium too.
If you double the diameter, but keep the same wall thickness it would just about be able to carry its own weight.
And, of course, it would be even more wobbly.

This isn't looking like a very viable idea.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 15/10/2018 22:07:39
.............Mmmmm , beeeer !
I was thinking more like Hyper-Guppy , with lifting-body .  Anyhoo , it would be flimsy by airplane standards , still better than blimp though .  Might be best to focus on the All-Engine VTOL near term , a special variant could be produced for tank transport .
........P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 15/10/2018 23:27:30
Transporting tanks is easy. Way back in the 1940s, both sides built wooden gliders that could be towed by a conventional bomber and carry a tank. Cheap (cheaper than a tank, which in modern warfare has an expected front line service life of about 60 minutes), effective, fast (up to 180 mph even then), and with minimal radar profile. Release at 15,000 ft, dive and cokscrew at Vne, deploy the brakes, and skid to a halt next to your infantry, with the tank engine running. Eventually , somebody thought it would be more sensible to fit a couple of engines to the glider, and the Guppy was conceived, but only the unpowered versions saw action.

Like I said, choose your problem first, then design the solution. If you want to move tanks quickly to the front line, use a glider. If you are not in a hurry, use a ship and drive from the coast. The prospect of a damn great airship appearing over a battlefield and landing at  10 mph can only bring joy to the enemy.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 16/10/2018 00:18:47
 You'ver got points buut , I was thinking of 200+ mph. and then VTOL down onto Hamburger Hill real fast .  Or it could compete with car ferries !
.....P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 16/10/2018 04:54:03
Seriously , such a craft could go back and forth , delivering and retrieving tanks and APCs .  Ditto civilian equipment to remote locations .  Finally , I am surprised that you didn't see the obvious .  Flying , amphibious Drone Carriers .  Today's capital ships desperately need constant , long-range cover and interdiction .  These could refuel from any ship , and sea-anchor most of the time .  They could also range far inland , and stay there indefinitely .
The Avengers exaggerated it , but the idea has merit .
Okay , bite the pad hard !
.........P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 16/10/2018 12:49:45
Retrieving tanks is never urgent. If you win, you need to keep some armor alongside your occupying infantry. If you lose, the tank will be scrap metal and roasted soldiers. Using plastics instead of wood, we could make a tank-carrying glider capable of 300 mph or more.

Delivering civilian kit to remote locations is quite a different prospect  That's pretty much what the Flying Bum (US: Flying Ass) is designed for; slow, no landing strip.

Choose your question, then design the solution. More Cessna 172s have been built than any other aircraft, 'cos it's extremely adaptable and dead easy to fly, but there's a difference between  the regular, cargo, STOL, desert and float versions, the wing is in the wrong place for crop spraying, and Vs is too high for light glider towing.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 16/10/2018 13:51:55
Touche ( unless the enemy melts you in flight ) .
Consider this though ; I'm winning because I keep recycling mildly damaged tanks through repair real quick . 
Also consider ; I'm in my car waiting to commute to work 100 miles across the straits .  Do I want to see a giant ass pop up over the horizon ?
What do I call THAT , the slow butt to China ?
....P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 16/10/2018 15:50:57
Recycling slight damage is done by field engineers, as the front line advances. Much quicker and easier to parachute in an engine - or even cannibalise one - than schlep the whole tank back to Detroit. If the front line is retreating, destroy anything that might be of use to the enemy, and regroup. Under no circumstances dangle your fighting vehicle from a dirigible, in sight of anyone with a decent rocket.

100 miles is about the minimum distance worth covering by air, unless there are special circumstances. The drive-on fast ferry across the Irish Sea (85 miles) runs at 45 kt and carries around 1500 passengers and 400 cars. Interestingly, it is likely to be replaced by a slower boat because it isn't economic - pity, because the breakfast is excellent! It's nearly always cheaper to fly and rent a car at the other end for business, and if you are going on holiday, another couple of hours on a regular ferry (a relaxing lunch!) is part of the fun.

I don't see the Flying Bum or any similar vehicle making a profit on a commuter route.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: wolfekeeper on 16/10/2018 16:19:11
FWIW the 'flying bum' Airlander has a top speed of 92 miles per hour, so provided the wind isn't as fast as that, it can still make headway. Airships often fly lower in the atmosphere than most aircraft, (well below the jet streams) where there's lower wind speeds.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 16/10/2018 17:01:28
Thanky , Wolfy !
About the tanks , that's a helluva job and risk for guys lugging around a torn up battlefield in trucks , trying to manhandle 60-ton tanks .  If the tactical situation deteriorates , they become bullet-sponges !  At 200 mph , the hybrid that scooped up the tank can have it at a temporary repair depot in 15 minutes .  It could be repaired there at least 10 times faster , and w/out loss of life or tank .  All live to fight the next day .
Of course pick-up & insertion would be done when the area was secure .  The procedures would only take a short while , so risk minimal , gain maximal . 
As to the civilian uses , large boats gulp fuel to plow through water .  Air is waaay less draggy , ergo , a fast hybrid might actually be economical .  Then there's specialized & automated cargo delivery , etc .
Hokay , maybe useful , definitely interesting .
.........P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 16/10/2018 17:23:20
Airlander is specified to 20,000 ft with a cruise speed of 80 kt.

It's generally preferable to fly above cloud for passenger comfort, so most non-jet traffic flies in the lower airways from 5,000 to 15,000 ft in the UK. Right now, the wind at Tingwall is 60 kt SW at 10,000 ft, Stornoway is 55 kt,  OK, it's a sea crossing so 2000 ft is safe (only 50 kt headwind all the way, but rough!)  but you'd get there quicker by boat! Fact is, if you regularly fly above 5000 ft, you need at least 150 kt cruise to make it worthwhile, and if you regularly fly below 5000 ft, you need rubber teeth. No way you can offer a service across mainland Europe below 10,000 ft.

The loiter speed for Airlander is 20 kt, so it can "hover" at 3000 ft or more on most days, but literally "falls short" of a zero-speed landing in anything less than a stiff breeze.

Worth noting that most licensed airfields are depicted on the charts with a "traffic zone". The Airlander base is marked "danger"!
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 16/10/2018 19:21:01
........Awesome people-mover .
Would it perform better with more powerful propulsion , and 1/2 the gas volume ?
.........P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 16/10/2018 19:36:04
I was thinking more like Hyper-Guppy , with lifting-body .  Anyhoo , it would be flimsy by airplane standards , still better than blimp though .  Might be best to focus on the All-Engine VTOL near term , a special variant could be produced for tank transport .

Stop dreaming and provide some sort of estimate of the cross sectional area your idea would have to push through the air.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 16/10/2018 19:37:01
Would it perform better with more powerful propulsion , and 1/2 the gas volume ?
On the whole, the more like a plane you make it, the more likely it is to work...
You might want to think about that.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Kryptid on 16/10/2018 23:41:44
........Awesome people-mover .
Would it perform better with more powerful propulsion , and 1/2 the gas volume ?
.........P.


It would accelerate and climb faster with a higher top speed, but you would take a hit to endurance and range (which are already very poor for your design). Of those two sides, transport aircraft have generally leaned towards longer range in place of high speed.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 17/10/2018 00:19:22
True , unless your top speed is 10 mi.per.hr.
D.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Kryptid on 17/10/2018 03:21:55
True , unless your top speed is 10 mi.per.hr.
D.

A problem that no conventional prop or jet transport aircraft has.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 17/10/2018 04:25:32
True , but lifting weight with them consumes a lot more fuel . 
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Kryptid on 17/10/2018 04:29:12
True , but lifting weight with them consumes a lot more fuel . 

Maybe more than a blimp, but not more than your design.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 17/10/2018 04:39:41
What , you don't like my giant butt ?
Let's make it a giant head instead !
P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Kryptid on 17/10/2018 04:41:27
So much for a productive discussion...
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 17/10/2018 05:57:03
Skuza , it's my Animal House days come back to haunt me !
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 17/10/2018 07:21:55
Stop dreaming and provide some sort of estimate of the cross sectional area your idea would have to push through the air.
So much for a productive discussion...
We can't have a discussion if you don't give us something to discuss.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 17/10/2018 08:16:21
So far we have discussed a machine for carrying passengers backwards in an airway, or exposing its crew to enemy fire whilst attempting to remove scrap metal from a battlefield. There being little market interest for either, I don't see much point in  discussing the details until someone finds a bit of the atmosphere around 12,000 ft altitude, that doesn't move.

This afternoon I'll be passing over the Flying Bum en route from Cambridge to Oxford. It's a great landmark, but that isn't the primary function of an aircraft.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 17/10/2018 11:41:00
...................Tank Yank
There is always ebb and flow on a battlefield .  Ebb is the time to go get your $7 million tank , and run it back to the depot for a quick and safe turnaround .  Meanwhile , you can be shuffling thousands of troops and their equipment around the battlefield fast enough to get pinch-offs galore on the enemy !  Drop a couple of  MOABs on that box and it's "enemy no more !" .
 Remember now , when I talk about the military stuff , I'm talking about the all-motor version .  The Hyper-Guppy version could work in certain civilian applications . 
Alrighty then !
P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 17/10/2018 15:07:50
Ledt's have a recap on the size, cruise speed and landing speed of your machine.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 17/10/2018 15:47:58
Okay , I'm big on the Flying Bum today .  How's about we cut it in half horizontally , so that it's much flatter . We give it powerful engines with VTOL propulsion . 
Top Speed : 200 mph.
MTO. & MLD. : 0 feet .
Alright , really high-speed ferry !
........P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 17/10/2018 19:14:27
OK, so we are talking about this
https://en.wikipedia.org/wiki/Hybrid_Air_Vehicles_HAV_304/Airlander_10

with these specs
Capacity: 10,000 kg (22,050 lb)
Length: 92 m (301 ft 10 in)
Wingspan: 43.5 m (142 ft 9 in)
Height: 26 m (85 ft 4 in)
Volume: 38,000 m3 (1,300,000 cu ft)
Gross weight: 20,000 kg (44,092 lb)
Max takeoff weight: 33,285[52] kg (73,381 lb)
Powerplant: 4 ◊ 4 litre V8 turbocharged diesel engines, 242 kW (325 hp) each


So, it can carry about 10 tonnes in load, and you are suggesting we halve the thickness- so the capacity falls to) a bit less than) 5 tonnes.

According to this page
https://www.army.mod.uk/equipment/combat-vehicles/
"Challenger 2 (CR2) is the British Army's main battle tank. ".

And it weighs in at 62.5 tonnes.
So you need 13 "half arses" to lift one.

Unlucky for some...
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 17/10/2018 19:22:04
Massive Contra-fan units , VTOL  and putting out 2to300k lbs. of thrust each double-disk propulsor .
Add that million pounds to your 5k!
Nyuh-nyuh-nyuh !
P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 17/10/2018 20:39:44
Massive Contra-fan units , VTOL  and putting out 2to300k lbs. of thrust each double-disk propulsor .
Add that million pounds to your 5k!
Nyuh-nyuh-nyuh !
P.
At which point you have a badly made helicopter
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 17/10/2018 21:06:22
That can lift half a forest , or a tank division , or a drone wing , or a blue whale , etc. , etc....
"Keptin , there be whales here !" .
P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 18/10/2018 06:59:51
There is a faint air of feasibility here. The largest available contraprop turbofans can generate around 12 tonnes of static thrust and weigh about 3 tonnes, so if the airframe and fuel weigh nothing, seven Kuznetsov NK12s could just lift a tank vertically.

That is why we don't recover battle-damaged tanks by airship.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 18/10/2018 07:28:19
300k lbs. of thrust
That's 5 times the thrust of the jet engine on a jumbo jet.
https://sciencebasedlife.wordpress.com/2011/07/25/extreme-engineering-the-boeing-747/

Please stop inviting "designs" that need magical ingredients which don't exist.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 18/10/2018 15:17:50
Gentlemanses ,
I just gave you time to research monster turbofans .  Letís take my fave. , the GE-90 .  Manufactured over a quarter-century ago , it's maximum sustained ( 30 hrs.) static thrust at sea-level is documented as 130k.lbs .  We could do much better nowadays .  150k.lbs is conservative .  A free-turbine double-disk version would thus produce 300klb of static turbo fan thrust per propulsor .  Yes , that is almost five 747 engines , ain't progress great ?!
Go ahead and fetch yer mega-tank, Wardog !
P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 18/10/2018 16:54:18
True, a GE 90 could lift 6 times its own weight compared with the contraprop 4 times, giving a payload of 40 tons per engine if we ignore the weight of the rest of the aircraft. You can eliminate the need for a tank altogether by just flying your machine over the enemy and literally blowing them away.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 18/10/2018 17:27:46
Yaaaas , M.O.A.B.s !!
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 18/10/2018 19:30:18
Letís take my fave. , the GE-90 .  Manufactured over a quarter-century ago , it's maximum sustained ( 30 hrs.) static thrust at sea-level is documented as 130k.lbs . 
And its rated thrust was a lot less
" with thrust ratings from 81,000 to 115,000 lbf"
 from
https://en.wikipedia.org/wiki/General_Electric_GE90

So, what you are saying is we could magic 100,000 and pretend that it is 300,000 them magic it some more to make it able to sustain that peak performance indefinitely.
Meanwhile, you magically lift the 8 tons or so of engine into the air with a blimp that has a capacity of 5 tons on a good day.

At which point, as I said, you made a shockingly bad helicopter.
If you can vector 1500 tons of thrust you can lift what ever you damned well please.

What's the point of the bag of helium at this point?
It's just an anchor, mired in the air.


Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 18/10/2018 20:03:01
i may have found a use for the gas bag- it can hold up the fuel.
If this is right
https://www.airliners.net/forum/viewtopic.php?t=771027
The engine burns about 16 tons per hour.
So 5 tons would run it for about 18 minutes.
As far as I recall, you were thinking of using 4 of them.
So that means the balloon bit could carry enough fuel for nearly 5 minutes.
With a top speed of 200 MPH that's long enough to cover about 15 miles
In most urban areas there are fuel stations that close together so we should be OK, as long as you can use diesel- that's probably OK in a jet engine.
So, your 15 mile hop takes 5 tons of fuel- that's roughly 5000 litres at £1 per litre or so.
Only £300 per mile.
To be fair, that's only 10 times the cost of my local taxi company.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 18/10/2018 22:06:25
...........Oh , ye of little faith !
Let us examine the GE-90's normal performance .  A 777 cruising for 15 hours consumes under 200klbs of jet fuel , utilising 2 engines at 1/2 throttle .  A "flying diaper" with 4 pairs of these might consume 4 times as much while heavily loaded and going flat out , but it only transports a short distance .  Mostly , it would be loading , unloading , or standing by .  The all-engine version would consume more while hovering , but would have a jet-like top-speed .  Either version would do mostly short trips  , with cargo .  The gas-bag version would work like a powered para-glider ; it would save gas .  The all-engine version would function as a giant VTOL jet .  1.2mlbs. of thrust gives you a lot to work with !
 See how much better simple and clear math makes everything ?
Alright , save nation , peace .....P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 18/10/2018 22:36:30
Your "flying diaper" seems to  be doing its job. It's been taking the p*** and it's full of  s***.
Perhaps it's time you changed it.
See how much better simple and clear math makes everything ?
Yes, I do. That's why I did some.
You should try it.
However, if you start by inventing numbers, then doing maths, you don't get anything meaningful.

Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 18/10/2018 22:42:42
Well , if a cheap piece of wood could do it , a powerful flying machine could do it !.....P
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 18/10/2018 23:17:09

To be fair, that's only 10 times the cost of my local taxi company.


We have often accused each other of living on a different planet Now I am sure of it. London black cab is £2.74 per mile, New York around $3: a hundredth of the cost of PMM's jet-powered arse.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 18/10/2018 23:38:03
Anyway, whilst we remain in the EU, let's assume an infinite budget for zero-weight fuel (like Cadarache) and get this beast off the deck. 5 minutes later, in the midst of a firefight, we need to hover and lower our swinging sergeant to attach the lifting chains to a scrap tank, without setting fire to either, or blowing desert dust, trees or jeeps into the colonel's tea. Never mind the absurd physics, or Sarge's blue vocabulary, how do we persuade Johnny Foreigner to play the game and not fire his Katyushas at the enormous floating bag of JET-A1? Or even a burning arrow?

Worth a visit to the Lancaster museum at East Kirby. There's a superb display about the Dam Busters, including  a recording of the bombardier talking to the pilot . Lying on his stomach at 50 ft and 240 mph over a lake in pitch darkness, with flak bursting all around, he said "Skipper, this is bloody dangerous."
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 19/10/2018 00:35:23
We fully secure the area first , then LAND right near the broker , winch it aboard , and jet back to Hogan's Garage for quick repair , and re-deployment . 
P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: syhprum on 19/10/2018 03:21:21
London cabs have an ingenious navigation system so that a one mile trip involves traveling 5 miles 
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 19/10/2018 03:53:11
That's better than leaving their cab to be stripped everytime it breaks down .  Also better than sending a mechanic into a bad neighborhood to fix it , whereupon he gets killed .
P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 19/10/2018 07:30:59

To be fair, that's only 10 times the cost of my local taxi company.


We have often accused each other of living on a different planet Now I am sure of it. London black cab is £2.74 per mile, New York around $3: a hundredth of the cost of PMM's jet-powered arse.

I got the numbers here
https://www.numbeo.com/taxi-fare/in/Sheffield
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 19/10/2018 07:32:06
We fully secure the area first
Start by winning.
Always a good option- as long as you can use magic.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 19/10/2018 07:33:00
how do we persuade Johnny Foreigner to play the game and not fire his Katyushas at the enormous floating bag of JET-A1? Or even a burning arrow?
I was wondering about tracer fire- but the effect is the same.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 19/10/2018 08:39:14
The Flying Diaper is for civilian use.  The All-Engine is for military use .  Think giant , faster Chinook .  Drop a division off in the morning , encircle and concentrate enemy by evening , drop simultaneous MOAB bombs before dark , recover forces through the night , rest and recoup the next day .  Keep biting off chunks of the enemies forces until he collapses or is dust !
There y'are .  We win , they die !
Long live Amelica !
.........P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 19/10/2018 16:26:50
Straight talking from the land of the loser. Vietnam, Afghanistan, Iraq, Iran, Grenada, Cuba....now run by a gung-ho president who has never paid any tax because his enormous inherited business has never made a profit.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 19/10/2018 17:06:43
Vietnam was held until we didn't really want it anymore .  The next two were won , then withdrawn from. The last 3 were just simple military actions .  Don't forget who we were really fighting in 'Nam .
Wouldn't it have worked better if we could've shuttled around thousands of troops quickly and easily , instead of just dozens ?
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 19/10/2018 17:24:31
Aha, Trumpese has supplanted English at last.

https://www.bbc.co.uk/news/world-us-canada-41016347 includes
Quote
Professor Barry Posen of MIT has suggested that a US departure from Afghanistan would energise other countries in the region, like Pakistan, Iran, India and Russia, to exert themselves to prevent Afghanistan from becoming a failed state.
So going home and leaving someone else to clear up the mess equals "winning".

https://en.wikipedia.org/wiki/American-led_intervention_in_Iraq_(2014Ėpresent)#October_2018
Quote
On 4 October 2018, an operation against ISIL was started by the Iraqi military along with the military forces of France and the United States under the CJTF-OIR coalition in the Anbar Governorate around the city of Qaim and the Syrian border where ISIL continues to operate and maintain a strong and large presence.[265] During the operation ISIL claimed to thwart an American-led assault near the Syrian border and also claimed to have killed 3 US soldiers and wounded 4 others in the clashes, the US military has not confirmed or denied the claimed losses.[266]
On 5 October 2018, US-led Coalition planes bombed an ISIL position in the village of Kushaf near the Tigris river in the Kirkuk Governorate, reportedly killing 6 ISIL members, on the same day ISIL detonated a roadside bomb killing an oil employee and injuring 11 others in a bus in Baiji in the Saladin Governorate, and in a separate attack in Fallujah in the Anbar Governorate ISIL detonated a car bomb injuring an Iraqi policeman and 3 others.
gives us yet another definition of winning: deploying vastly superior forces and losing personnel and civilians.

The problem is, my friend, that Johnny Foreigner just doesn't understand your concept of winning. Nor does he have much enthusiasm for being encircled, concentrated and wiped out. To quote an oft-heard dictum: no battle plan survives first contact with the enemy. In the scenario you present, your best hope is that the bad guys will laugh themselves sick at the sight of the flying bum, before getting drunk and setting fire to it.


Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 19/10/2018 17:48:39
Guerrilla strikes are not army versus army on battlefield .  The Flying Arsenal is CIVILIAN .  The ALL-ENGINE could enable our own surprise strikes .
Military strategists love tactical soldier-droppers !
P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 19/10/2018 18:14:11
The only civilian Arsenal is the world's greatest soccer team - and even they are named after the military unit where they originated!

Military strategists did not take part in the Arnhem debacle. nor, it seems, have they seen "Once Were Soldiers".

I don't think there have been any serious pitched battles since Kursk. The first Iraq war turned into a sick joke with Saddam's army deploying modern tanks in a pre-tank static array, wholly at the mercy of naval guns and (fast, heavy) jet aircraft.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 19/10/2018 18:58:27
In the scenario you present, your best hope is that the bad guys will laugh themselves sick at the sight of the flying bum,
:-)

Thus far, I think the OP's only major achievement is to get a sustained agreement between  me and Alan about something.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 19/10/2018 19:16:28
It's Arse , not Arsenal . Spell-checker bites .
You two agree the ARSE is no good militarily , but I'm pushing the all-engine lifter for military purposes !  Speaking of Iraq , might have been easier to drop Simultaneous MOAB pseudo-nukes on those formations . Much easier to place them perfectly from slow-moving platforms , than C-130s . 
You could call them "The Erasers" !
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 19/10/2018 20:10:27
So we have arrived at a heavier-than-air machine capable of vertical takeoff and delivering military personnel or hardware more quickly than trucks, by virtue of rotating fans.

Leonardo da Vinci first proposed this in about 1450, but it took another 500 years to get it to work. You can buy them in various sizes with up to 20 ton lift (Mil Mi26), or ask the Russians to build another Mil V12 which had a 40 ton lift. AFAIK none of these has lifted a modern main battle tank but they have used an Mi26 to rescue damaged Chinooks!


Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 19/10/2018 22:05:51
Tur-bo-fans ! They have lifted all kinds of things .  Helicopters , however , bite bad .  They are weak , awkward , and fall out of the sky all of the time , just research 'Nam .  No chopper is going to lift or move what this proposal could , nor could it survive as well either .
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 20/10/2018 00:15:31
but I'm pushing the all-engine lifter for military purposes
So, you finally accept that the "airship" version is... pants.

Better late than never.
You could call them "The Erasers" !
You could call them "pipedreams"

Helicopters , however , bite bad .  They are weak , awkward , and fall out of the sky all of the time ,
So, why do you propose building them ? (And hamstringing them by making them carry a gas bag)
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 20/10/2018 00:32:52
Vectored thrust with turbofans has been done, and now HM Government has pensioned off the most successful combat aircraft since the Spitfire whilst the US Marines are moving from AV8s to more conventional fixed-wings and helicopters. There has to be a reason for this change in frontline air support.

Meanwhile, we await the return of the classical pitched battle in which a line of tanks and infantry advances against an enemy with such weak antiaircraft capability that it is militarily and economically worthwhile to deploy some gargantuan version of a kid's drone to recover a slightly damaged tank in those rare circumstances where a truck or tracked recovery tractor cannot follow the course of the advance. When such a situation arises, and we have bred a new, fireproof version of the dope on a rope,  who can descend from a hovering flying saucer and attach chains to the miraculously-undamaged lifting eyes of said tank, plus some means of preventing the tank from oscillating in the downwash as the assembly staggers back into the sky.....we'll let you know.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 20/10/2018 03:07:51
Vectored thrust w/turbofan has been done a lot , is being done a lot , and will continue being done a lot! 
The USMC. apparently has issue with the Harrier's danger level .  They definitely can't afford the obscenely expensive F-35 , so they have to settle for conventional craft .  If there was a "Super VTOL"
giant Chinook-type craft available don't you think they'd be drooling at it ?
In regards to battlefield operations ; quickness , flexibility , and capability , have always been critical to success there .  A super-transporter would be of immense value in a long list of military capacities , much as the CH-47 and HH-53 have been to date .
The synchronized MOABs could be dropped from great height while maneuvering at speed .  With present digital systems , perfect placement and timing could be achieved . 
Once again , Flying Butt-civilian .  All-Engine - military .
Indispensable VTOL , as helicopters have been for 70+ yrs !
P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 20/10/2018 10:54:41
If there was a "Super VTOL" giant Chinook-type craft available don't you think they'd be drooling at it ?

Not for troop deployment at the front line. Too many eggs in one basket. Likewise heavy tanks. Once the line has advanced, you can shift stuff in and out of held ground quicker and cheaper with fixed-wing transport, and there's no point in your heavy armour moving forward faster than a quick march.

Integer programming was invented by the US Navy on the realisation that continuous mathematics produced elegant but useless tactical solutions like "0.637 aircraft carriers", so you either have to begin with fixed small numbers of actual large assets, or deploy large numbers of smaller assets to get closer to the optimum solution. Marines are all about rapid advance to establish bridgeheads with light weaponry, plus flexible air cover (Harrier, Apache) for solving particular problems that need rockets or bombs. Dropping a heavy tank on the front line, or behind enemy lines, with no infantry and established supply line, is just creating an isolated target - worth watching "Beast of War" (probably "The Beast" in the US) to see what happens to a tank out of context.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 20/10/2018 12:20:10
and we have bred a new, fireproof version of the dope on a rope,  who can descend from a hovering flying saucer
He needs to be able to work in winds that make a hurricane look like a Summer breeze too.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 20/10/2018 14:49:08
I knows that , Mr.C. ,
not suggesting a "tank toss" to the enemy . Not suggesting injection AT the front , but behind it .  Giant VTOL would enable fast , not slow , tank movement , often to rough or inaccessible terrain .  It could even be to isolated pockets , or forces inserted behind enemy lines .  Think of how many times forces have been devastated because they were cut off , and reinforce-ments could not reach them . This system could directly inject troops , tanks , apc.s , logistical supplies. , and many other game-savers . This is why V-22 Osprey is so valued .  The military has always pursued VTOL , and for damned good reason .  I say that  this system is an excellent solution to their quest.
P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 21/10/2018 10:35:19
Think of how many times forces have been devastated because they were cut off , and reinforce-ments could not reach them
Yes, the last thing you want to be part of is an isolated force behind enemy lines.

This system could directly inject troops , tanks , apc.s , logistical supplies. , and many other game-savers

So, you can use it to set up an isolated force behind enemy lines.

Is it just me, or is there some sort of problem with that?
not slow , tank movement , often to rough or inaccessible terrain

Terrain inaccessible to tanks is
(1) quite rare
(2) not somewhere you want to put your tanks

Long ago some people living near me were getting some bricks delivered- by a truck with a crane.
The driver mentioned that the crane could lift 2 tons.
Their neighbors said "so, you could pick up our car + put it over the wall and  into the garden for us?".
The driver said yes, he could but he didn't think it was a good idea.
The neighbours disagreed.

Until the driver said;
"Sure, I can get the car in. How do you plan to get it out again?"

Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 21/10/2018 12:11:30
                 Tank Injection .
The tactics of warfare .  There are definitely times when injecting a force behind enemy lines can break his back .  Witness your wooden gliding-tanks .  That risk was taken when it was deemed worthwhile strategically .  Giant VTOL could take forces across enemy lines , across impossible terrain , shuffle them around when necessary , and retrieve them when  needed .  All this far quicker than a truck that got stuck . 
Extreme mobility man , glad the damned Nazis didn't work this one out ! 
P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 21/10/2018 13:29:56
That risk was taken when it was deemed worthwhile strategically . 
That risk was taken (By young men in tanks) when it was deemed worthwhile strategically (by old men in  armchairs).


You seem to have failed to understand that the enemy might take a rather unsporting view of a huge flying  fuel tank passing over his head.
Do you recall the comments about tracer rounds and fire arrows?
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 21/10/2018 16:10:56
 That is  what CAMPS , IRON CURTAIN , and a long list of anti-missile & RPG technolog|is are for .  As for old men , we desperately need their knowledge , experience , wisdom , and emotional maturity .  These enable success , rather than rash action , and ignoble defeat .
Protect it like a Chinook , and you've got a winner ! 
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 21/10/2018 16:40:30
Protect it like a Chinook , and you've got a winner !
The biggest target is the gas bag.
Remove that, and you pretty much have a big Chinook.
(The design of the Chinook is a bit older than I am; does it count as wisdom, or do you plan to get rid of it?)
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 21/10/2018 17:31:27
They could wind up fielding Osprey or Chinook class VTOL , or maybe go T-Bucket on older ones .  The desert is full of possible modifieds, pretty inexpensive too !
Gasbag ? Drones maybe ?
Either of above is safer than helos.
D.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 21/10/2018 21:33:17
They could wind up fielding Osprey or Chinook class VTOL , or maybe go T-Bucket on older ones .  The desert is full of possible modifieds, pretty inexpensive too !
Gasbag ? Drones maybe ?
Either of above is safer than helos.
D.
The gas bag is still a huge target.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 21/10/2018 23:23:14
Let's look at the numbers invoved and the outcome of a famous drop behind enemy lines.
Quote
Market would be the largest airborne operation in history, delivering over 34,600 men of the 101st, 82nd and 1st Airborne Divisions and the Polish Brigade. 14,589 troops were landed by glider and 20,011 by parachute. Gliders also brought in 1,736 vehicles and 263 artillery pieces. 3,342 tons of ammunition and other supplies were brought by glider and parachute drop.[58]
To deliver its 36 battalions of airborne infantry and their support troops to the continent, the First Allied Airborne Army had under its operational control the 14 groups of IX Troop Carrier Command,[59][h] and after 11 September the 16 squadrons of 38 Group (an organization of converted bombers providing support to resistance groups) and a transport formation, 46 Group.[60]
The combined force had 1,438 C-47/Dakota transports (1,274 USAAF and 164 RAF) and 321 converted RAF bombers. The Allied glider force had been rebuilt after Normandy until by 16 September it numbered 2,160 CG-4A Waco gliders, 916 Airspeed Horsas (812 RAF and 104 U.S. Army) and 64 General Aircraft Hamilcars. The U.S. had only 2,060 glider pilots available, so that none of its gliders would have a co-pilot but would instead carry an extra passenger.

It was a failure.

I don't think inserting one unsupported tank behind enemy lines would win a war. "Kelly's Heroes" was fiction, not history.


Quote
As for old men , we desperately need their knowledge , experience , wisdom , and emotional maturity
Are you thinking of Hitler or Trump? Or Lord Cardigan (Charge of the Light Brigade) perhaps?
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 22/10/2018 03:00:35
           Hokay , hokay , hokay !
It sounds like they overeached a bit !  Could it have succeeded if the gliders were able to constantly shuttle back and forth to bring in ever more troops and supplies ?  I have to believe that they did this massive injection because such had worked in the past .  Like any tool , it's how you use it .  I definitely would prefer wise OGs running this than impulsive hot-heads !  Gents like Eisenhower or Nimitz would handle it well .  There's good & bad in any lot , you have to choose wisely .
Lastly , the "Flying Diaper" MIGHT have special purpose applications , then again , it might not .  Time will tell with that one .
OK , imagination's real ! 
P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 22/10/2018 10:47:42
A glider cannot shuttle. There was no historic precedent, though everyone knows that a shock invasion may win a battle but can quickly turn into a defensive seige if you can't establish a supply line. Stalingrad, Khe San and a few others show the importance of this fairly obvious fact.

Eisenhower and Nimitz were indeed behind a number of unsuccessful initiatives. The Allies won because (a) Hitler believed his own propaganda (b) you can't beat the Russian winter (c) Allied production facilities were enormous and way behind the front line (supplies again) and (d) the atom bomb had a greater effect on Japan than the V2 had on England.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 22/10/2018 14:18:01
You make my point for me , mahn !
Gliders can't shuttle around , but a Chinook sure can !  That be why the military loves'em .  They can definitely maintain a robust supply and reinforcement line , even across treacherous , or enemy-filled , terrain . 
Also , I'd much rather have Chester Nimitz gamble w/my life , than an emotionally immature Hitler !
Hokay !..........P
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: alancalverd on 22/10/2018 16:51:36
Interesting that Nimitz was promoted within a closed and largely unaccountable meritocracy, whereas Hitler, Trump, and George W Bush were democratically elected. But I digress.

Reading the Wikipedia article on the Chinook, it seems as vulnerable as it is useful, with as many destroyed in action as have played a part in a successful penetration, though there is no doubt that it is a very handy piece of kit to have behind the front line.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 22/10/2018 19:19:43
It hadn't occurred to me before, but the "driverless car" is a neat improvised anti tank weapon against a tank that's stuck in the middle of nowhere.
Just keep driving cars up to it. Since it can't tell which ones are full of explosives (make sure a few are), it has to shoot at all of them.
Once it runs out of shells and fuel, you just wait for the occupants to starve and surrender.

On a related note, how do you "scuttle" a tank?
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 22/10/2018 19:23:02
..............I like Ike ,
but Bush and Trump are on Hitler's level of maturity .
The Chinook is beloved for the same reason the Osprey is ; it can deliver and it can pick up .  That is a life-saver !
P.M.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Professor Mega-Mind on 22/10/2018 19:27:58
  To B.C. - Shuttle , not scuttle .
                   Spell-checker bites .
About the cars , wouldn't dirt limit their access ?  Also , wouldn't bazookas be a bigger threat ?
P.
Title: Re: Are heavier-than-air hybrid airships a good idea?
Post by: Bored chemist on 22/10/2018 19:59:15
  To B.C. - Shuttle , not scuttle .
                   Spell-checker bites .

No.
I said scuttle, because I meant it.
https://en.wikipedia.org/wiki/Scuttling

Please check your own knowledge before assuming ignorance on the part of another.