[Professor Mega-Mind (OP)]

      ......  ..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.

[Bored chemist]

      ......  ..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.

[Professor Mega-Mind (OP)]

.............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.

[alancalverd]

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.

[Professor Mega-Mind (OP)]

 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.

[Professor Mega-Mind (OP)]

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.

[alancalverd]

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.

[Professor Mega-Mind (OP)]

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.

[alancalverd]

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.

[wolfekeeper]

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.

[Professor Mega-Mind (OP)]

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.

[alancalverd]

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"!

[Professor Mega-Mind (OP)]

........Awesome people-mover .
Would it perform better with more powerful propulsion , and 1/2 the gas volume ?
.........P.

[Bored chemist]

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.

[Bored chemist]

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.

[Kryptid]

........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.

[Professor Mega-Mind (OP)]

True , unless your top speed is 10 mi.per.hr.
D.

[Kryptid]

True , unless your top speed is 10 mi.per.hr.
D.

A problem that no conventional prop or jet transport aircraft has.

[Professor Mega-Mind (OP)]

True , but lifting weight with them consumes a lot more fuel . 

[Kryptid]

True , but lifting weight with them consumes a lot more fuel . 

Maybe more than a blimp, but not more than your design.