Naked Science Forum
Non Life Sciences => Technology => Topic started by: Professor Mega-Mind on 21/09/2018 16:52:41
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Best A-10 Replace. Design
The optimum battlefield attack aircraft would have excellent performance , good efficiency , and great survivability . The A-10 Warthog has been the best example of this type aircraft in the modern era . Bringing the characteristics & capabilites of the " Tank Buster " forward into the 21st century , while greatly improving them , is a significant design & engineering challenge . The proposal put forth here uses several planform & propulsion system modifications to achieve these design goals , plus adds in the capability of fully loaded VTOL flight . All of these while retaining a similar speed regime to the Warthog .
The key to this design architecture is the free-turbine concept . Used for decades now in many industrial and military applications , the free-turbine is a proven technology , with many variations & derivations still unexplored & undeveloped . The proposal herein is to use the free-turbine effect to provide seperate & segmented power for the aircraft propulsors . A single yet powerful turbine power plant embedded in the aircraft fuselage , can duct hi-pressure exhaust through 4 short/stout wings ( Dragonfly configuration ) to 4 seperate hi-perf. ducted-fan units . Each unit rotatable from 90° thru -20° attack angle . When at 90° ( parallel to ground ) the two ducts would conjoin , with a slanted interface , for stability . The contra-rotating fans then give superior level-flight performance , with no chance of engine damage from bullets or shrapnel . The engine-core would sit in a protective trough within the fuselage , invisible to infrared detectors . Should a fan be stricken , automatic cut-off valves would seal off that tube , thus maintaining pressure to the other fans .
A small V-tail would aid stability, while a flat-panel , transparent-aluminum " knife-head " cockpit would protect the pilot from both birds & projectiles . A passive , lean-back G-Couch could greatly increase Max.G-Load , while shrinking minimum turn radius .
Some/all applications could forego wheel assemblages , using skids instead to reduce weight , increase internal volume and reduce maintenance and procurement cost and labor requirements .
This aircraft could easily be based on Naval capital ships , and transport vessels as well . A net-capture , and lightweight bunker system would seem optimal here , as VTOL maneuv-erability & compactness would be well above those of the large helicopters previously used .
Alright , there you have it folks ,
The " I live , we win ! " plane !
Your critiques are welcome ..P.M
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The Harrier did pretty well in this role but was difficult to fly compared with the more conventional A10. The use of two engines on the A10 was deliberate - you can recover with one dead. Leaning back improves the pilot's g-tolerance for dogfighting and air defence but you need to look down for ground attack. If you are going for net recovery, better to do away with the human pilot altogether: some version of a loitering drone plus A-G missiles is a lot more economical and can perform several functions (recon, intel, comms and attack) simultaneously by having several people "crewing" a machine no bigger than a single-seater, in ground-based comfort.
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You kick butt & take names , a.c. !
I'm thinking that pilots of these two legends would go to war over this , but I'll just say ; Harrier - VTOL , Warthog - Toughness .
The " Dragonfly " or " Dragon " that I am proposing would embody the best of both models . A 2-engine design ( 1 per wing ) could work well . HUD visors could allow fully prone ( 16 G ? ) couches , drones are becoming de reguer , but the possibility of electronic sabotage is always there . Perhaps man & machine teams ?
Anyhoo , got to goo ( har-har )..P.M
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4 short/stout wings ( Dragonfly configuration )
Double wing platforms like that are usually inferior to more conventional designs. The turbulent air coming off of the first wing interferes with the function of the second wing. This increases the drag and decreases the lift of that wing.
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True that , Mr. Kryptid , however...
there be tradeoffs here ! Like these:
A.- The quad-engine layout . This allows for contra-rotation , the advantages of which are many .
B.- The thick wings .This allows for greater fuel capacity & G-Loading .
C.- The short wings . The plane can fit in small spaces & shelters . Different wing heights would be used .
I put it forward here that a good alternative would allow engine movement during level flight , thus engendering , in-effect , thrust-vectoring .
Overall , net gain methinks!...P.M.
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A.- The quad-engine layout . This allows for contra-rotation , the advantages of which are many .
That can be done with a single engine if you mount two contra-rotating propellers on it.
B.- The thick wings .This allows for greater fuel capacity & G-Loading .
Which also increases form drag.
C.- The short wings . The plane can fit in small spaces & shelters .
Which increases lift-induced drag.
Overall , net gain methinks!...P.M.
The only way to know that is by conducting a trade study. You would need to compare the performance of the aircraft against other designs to see if it really is better or not. Even the professionals do that. I own a book called Aircraft Design: A Conceptual Approach by Daniel. P Raymer. It goes into significant detail as to why aircraft are designed the way that they are and how you can use equations to predict an aircraft's characteristics. If you're interested in serious aircraft design, it's an excellent book that I would highly recommend.
On another note, there really is no such thing as an optimum battlefield attack aircraft. Whether an aircraft is optimal for the job or not depends upon the design requirements. Different battlefields with different rules of engagement and different locations around the Earth will strongly affect how the aircraft needs to be designed. How far is it from your closest base? What are the natives armed with? What methods of detecting enemy aircraft do they employ? All of these will lead to specific requirements that will need to be reflected in the design.
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You are an excellent Mr. Critic , Mr. Kryptid ! If I didn't have this darned ADHD I might be able to sit still & read a book titled " Fingernails on a chalkboard ." As is , I'll have to beg off on that little pleasure until I'm reborn ! Having said that , I am aware of the effects you mentioned . My countering principle is this : With enough power you can make a brick fly .
How powerful of turbine power-plant could have fit in place of the Harrier's Spey turbofan ? Try 3to5 times the horsepower . Multiply that by 3 ( propfan ) and how much total thrust does your somewhat longer Harrier have ? Obscenely high thrust aside , are you really comfortable with the Harrier's "just crash anywhere..." stability ? With the F-35s "help , I've squatted down and can't get up !" performance ?
The raw power of my proposal would make for hellacious performance , even if it's efficiency wasn't stellar . THAT is military !
In closing , I have to believe that the boots on the ground would love having a super-plane hidden amongst them , right at the throat of the enemy . Can you say "Element of surprise." ?
Okay , said my piece ........P.M.
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Try flying prone for more than an hour.
I have to believe that the boots on the ground would love having a super-plane hidden amongst them , right at the throat of the enemy .
Not if they have to build and defend a runway, hangar, ammunition store, fuel dump, workshop and canteen for the 10 technicians and 2 pilots needed to keep the aircraft working. The object of tank and infantry warfare is to advance as quickly as possible and occupy territory as thinly as necessary to control it, not to drag an air force around the planet. VTOL simplifies the requirement but 600 mph means that you can call up as much weaponry as you need from a properly equipped and self-defended base 10 miles behind the front line, and have it delivered in one minute.
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Essentially true . I'm thinking that you can get that 10 miles effect without all of the rest needing to be close. A fuel truck could be an enabler ...think of the plane as a Huey combined w/a tank . Troops would beg to have that nearby , especially if it was fitted with transport options , like hooks & nets . Okay , same book , different page . ...............P.M.
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My countering principle is this : With enough power you can make a brick fly .
Which is a bad principle to build an aircraft by. Ignoring efficiency will hurt you in the long run. It will make your aircraft accelerate more slowly, slow down more during turns, have a lower top speed, have a shorter range and cost more in terms of how much fuel it will burn over its service life.
How powerful of turbine power-plant could have fit in place of the Harrier's Spey turbofan ? Try 3to5 times the horsepower . Multiply that by 3 ( propfan ) and how much total thrust does your somewhat longer Harrier have ?
Please provide a link showing where you got those numbers from, and don't say "I extrapolated".
Thrust is not just a single number. It varies with altitude and speed. If Engine A generates more thrust when it's stationary and on the ground than Engine B does, it's still quite possible that Engine B will generate more thrust than Engine A when both are moving at, say, 200 miles per hour. You can extract large amounts of thrust from an engine by using a high bypass ratio (or larger propellers) when it's static, but those same engines tend to lose thrust more quickly as they go faster because they have lower exhaust velocities.
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With enough power you can make a brick fly .
But in this case, the brick has to bring its own power. And fuel has mass too, so the amount of fuel needed to get the same distance and speed will grow faster than linearly with the mass of the "brick." That also doesn't account for acceleration. Above you specified the desire for high maneuverability--this is completely at odds with a heavy aircraft.
Very soon, I think that the optimum battlefield attack aircraft will probably be swarms of small drones, with an assortment of small and purpose-specific weapons for anti-personnel, anti-vehicle, anti-drone, and area denial tactics.
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A fuel truck could be an enabler
The last thing you want on the front line. At best a hugely visible explosive target, at worst an asset for the enemy to capture ...think of the plane as a Huey combined w/a tank .
Like a Chinook, perhaps? Very handy, but always based well behind the action. And I think there is a reason why tanks have tracks, not wings. Something to do with very big guns, hiding in terrain, and providing armour that moves at the same rate as the infantry. Troops would beg t o have that nearby
I doubt it. The front line is for fighting, not for refuelling and repairing machines, or for feeding and defending the umpteen very expensive blokes (including offduty aircrew) who do that. If you want medevac, you want to go to a hospital away from the enemy, so that is where you keep fuel (and fast-refuelling kit) and ammunition.
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Ookay , K. ( Chiral ) !
Let's just get reediculus , and jump to the Dino engine : the GE-4 .
2 feet wider than Olympus , 4 feet longer , 6K lbs. heavier , and 50K pounds thrust dry . Modern engineering could greatly reduce these spec.s while keeping the thrust . Propfan propulsors would multiply that # by 3 , while providing reasonable fuel usage & loiter time . A quad layout , times incredible power , times thrust vectoring , time's 16G , time's VTOL sounds like a fighter-pilot's wet-scream to me !
Maybe you like your " I die quickly! " Machete or whatever , but I vote for Victory myself .
As an aside ; I can see drone-teams commanded by a human system manager embedded , or nearby . Purely remote systems will probably prove to be too vulnerable to enemy interference .
Anyhoo , keep critiquing !....P.M.
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Propfan propulsors would multiply that # by 3
Again, where are you getting this from? It sounds very suspect.
time's 16G
So you want to kill the pilot now?
sounds like a fighter-pilot's wet-scream to me !
I thought this was an attack aircraft? What you have would make for an exceptionally poor fighter aircraft.
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Turbojet vs. Turboprop should be in some unspeakably boring book somewhere . Prone position in a custom-molded G-Couch should easily withstand 16G for short periods , I have read of much above this . Lastly , the power and maneuverability would definitely qualify this as a subsonic Fighter/Attack aircraft .
Honestly , I think fighter pilots would run to get in this beast !.P.M.
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Can I now assume that the whole "propfans give three times the power of jet engines" was pulled out of thin air?
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Prone position in a custom-molded G-Couch should easily withstand 16G for short periods ,
But my question was whether you have tried flying prone for an hour. The RAF, USAF and Luftwaffe have built prone prototypes
A much modified Gloster Meteor F8 fighter, the "prone position/prone pilot" Meteor, was used to evaluate the effects of acceleration/inertia-induced forces while flying in a prone position. Along with the Reid and Sigrist R.S.4 "Bobsleigh", the Gloster Meteor was engaged in a proof-of-concept experimental programme that proved in practice that the difficulties of operating the controls of the aircraft outweighed the advantages of sustaining higher "g" effects.
Now available at a scrapyard near you.
After millions of years, we have evolved with a visual field of more than a hemisphere. Sitting up, this gives us a lot of useful information about the terrain, threats and targets below, ahead and above us. Lying prone, all we can see is the (necessarily friendly) terrain we have already passed over, which, to a pilot, is as useful as the fuel you left in the bowser and yesterday's newspaper. Prone hang gliders are fun and even a novice civilian can pull the wings off without losing consciousness, but you still stand up for takeoff and landing, and in combat at 600 mph you need to see where you are going, not where you have been.
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I definitely meant laying back , not on stomach . This would require small , at hand , controls & visor-mounted video display of forward/ down . Unnatural , but deadly ...P.
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To Kryptid
Pull up some turboprop and turbo-jet engine spec.s . Compare SFC for engines of comparable static thrust . No turbofans ! Try older fighter engines vs A-400 engines , for example .
All done ..............P.M.
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To Kryptid
Pull up some turboprop and turbo-jet engine spec.s . Compare SFC for engines of comparable static thrust . No turbofans ! Try older fighter engines vs A-400 engines , for example .
All done ..............P.M.
That's not what I'm asking for. I'm asking for you to support the following claim about propfan horsepower with a good source:
How powerful of turbine power-plant could have fit in place of the Harrier's Spey turbofan ? Try 3to5 times the horsepower . Multiply that by 3 ( propfan ) and how much total thrust does your somewhat longer Harrier have ?
You made the claim. You provide the source.
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Alright ,I'll give an obvious example using a classic turbofan engine :
GEs TF-39 . This engine used a GE J-79 turbojet engine as it's power-plant . The stock J-79s maximum thrust was ~12k lbs. dry . When fitted with an 8/1 bypass ratio fan , the same engine delivered 43k lbs. of thrust dry . That is 3and1/2 times the max. thrust , and propfan rotors are 30% more efficient still !
Large blades multiply thrust quite massively , a J-79 sized modern turbojet core could easily create 50k lbs. of thrust per quad rotor . That , my friends , could do miraculous things !.........P.M.
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I definitely meant laying back , not on stomach . This would require small , at hand , controls & visor-mounted video display of forward/ down . Unnatural , but deadly ...P.
The word is semisupine. Standard position in gliders where we need to minimise cross-sectional area and provide maximum comfort with minimum upholstery: the seat is an integral part of the fuselage structure. Problem is that your view downward is restricted (poor choice for ground attack) and such matters as ejection seats (not fitted in gliders, and bailing out from a spin is extremely difficult) get complicated if you recline by more than a comfortable car seat - about 15 degrees. To say nothing of the vomit-inducing properties of a head-down vertical climb or a low-level passage under autopilot.
HUDs already contain a whole lot of unreliable distractions from the business of fighting. If you are going to remove the pilot's eyes from the front line, you may as well remove the pilot and use a remote control drone.
Everything in an aircraft is a compromise, which is why there are so many different types. 16g agility is best left to missiles, and an intercept and 6g dogfight at 40,000 ft is a very different matter from strafing, precision bombing, intel, paradrop or medevac. Horses for courses. By the time you have taught your carthorse and jockey to run, jump, play polo, cross country and pirouette, you have invested a lot of time and money in a single asset....and now you want to park it close to the enemy!
Don't confuse static thrust with power. If you fit a big enough gearbox, you can use a jet engine to tow a barge, but slowly. Power = thrust x speed and is fixed for any engine. You also have a tip speed limit of Mach 1 on any fan, so beware of using the same fan for lift (large, slow) and thrust (small, fast)
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You have more points than moose, mahn !
Methinks the Army wants their hi-powered , fast & maneuverable , VTOL , hideable bomb-truck , close enough to strike quickly at all times . The Marines scream for VTOL air support , from their tough positions . The Navy wants to have protective aircraft on all of their ships . Even the Air Force could use them for more survivable close-air-support . I could also see the Coast Guard needing sea-plane variants for land & sea interdiction .
I think that this " Dragon " would stand head & shoulders above any CAS aircraft extant today .
Peace through strength !....P.M.
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I've dealt with the undesirability of maintaining complex aircraft close to the front line, mindful of the fact that 10 miles is a day's fight for an army and a minute's flight for a jet. Close support does not mean having to defend the machine on the ground.
Harriers proved very useful for close naval defence and attack, but VTOL limits your bomb load which is why the (now scrapped, of course) Buccaneer was favored for ship-to-shore attack, and high level recon needs endurance, hence the old Gannet which could keep pace with the convoy for hours and provide primary radar with a 200 mile horizon.
Coastguard is all about low-level surveillance, the occasional depth charge, and SAR. Low and slow means a very different configuration from hi-g dogfights, at least two crew (looking downwards!) even for fishery protection, and lots of endurance (ideally two complete crews and 18 hour endurance). Your fighter-bomber carries weapons under its wings, so not a good idea to add floats and salt spray.
Given a mile of concrete and a clean hangar, you can fly a very sophisticated air superiority fighter that could not survive a deck landing or a desert takeoff. High altitude defence is another game, with different pieces.
Anyway it's all pie not in the sky. Noting that the UK is building aircraft carriers with no budget for aircraft, that well-known military authority Sandi Toksvig pointed out that it's a lot safer than having planes with nowhere to land.
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You be right , Mistah Calverd !
Real fighter would require different engines & planform , plus ducting supersonic exhaust is inefficient .
However , monster attack plane could work . It could have a large bomb load and/or huge fuel load , or tons of armor & weaponds , or floats , etc. . Hell , you could call it the " Bulletproof Plane " .
Let 'em tweak it the way they want I'd fly it !.......P.M.
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Alright ,I'll give an obvious example using a classic turbofan engine :
GEs TF-39 . This engine used a GE J-79 turbojet engine as it's power-plant . The stock J-79s maximum thrust was ~12k lbs. dry . When fitted with an 8/1 bypass ratio fan , the same engine delivered 43k lbs. of thrust dry . That is 3and1/2 times the max. thrust , and propfan rotors are 30% more efficient still !
Large blades multiply thrust quite massively , a J-79 sized modern turbojet core could easily create 50k lbs. of thrust per quad rotor . That , my friends , could do miraculous things !.........P.M.
You understand that horsepower and pounds of thrust are not the same thing, right? One does not correlate to the other. Also, just because one engine core is capable of generating 50,000 pounds of thrust using one fan does not mean that it can make four fans generate 50,000 pounds of thrust each. The core only has so much power to give. You might get more total thrust by using four fans, but each one is going to suffer a loss of thrust individually. So you can't simply multiply 50,000 by 4 and expect to get the correct thrust value.
Your design would also be very slow. It has high drag and high thrust lapse. I would be surprised if it could get anywhere near and A-10's speed.
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τBulletproof, eh? So the fuel tanks and engine cowlings are made from at least 10 cm steel...we are back to the flying brick.
There were some tank-carrying gliders around in WWII, which caused the enemy some concern when the convoy was attacked from behind, but I think you need to play around a bit with your slide rule before cutting metal on this project.
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Preface
50k.lb. pure turbojet ( gas turbine only ) thrust core .
4 seperate free-turbine driven fan disc's .
1 internal-protective engine-core trough . Extension could protect pilot and enhance structural integrity .
4 ballistic bands , 1 per disk .
4 lightweight , hi-strength engine shrouds .
4-engine independent thrust-vectoring .
4 thick wings providing more lift, weight , and fuel capacity .
1 or 2 powerful gas turbines to power this assembly .
4 fast-acting throttle-valves for free-turbine tubes .
~ of stunning modifications .
Okay , friendly bow ?......P.M.
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The mechanical engineer's dream: pre-machined pieces of unobtanium, held together with gossamer and powered by fairydust.
The pilot's nightmare: any approximation to the above. Especially if required to fly.
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Making Bricks Fly
Firstly , manses , there isn't a dang thing about military aviation that's
" safe " . Study the development history of the Harrier and you'll find that out . The Brits kept at it because it was VTOL is extremely useful in many situations .
Secondly , I have zero confusion about any of this . I may say "H.P." in a general sense , but I use precise thrust when quantifying
force applied . By the way , the turbojet translation is roughly 85% , in otherwords 85 hp.~100 lb. of thrust . Other engine types have different translation ( efficiency ) rates , finding precise #s can some times be problematic .
I believe that fly-by-wire , FADEC , & a host of new technologies and materials would make it easy to control a subsonic craft w/a good amount of wing/flap area , and 4 fully thrust-vectoring , quad-corner and hi-powered fan units , under instantaneous , FBW control . Many past incidents have shown the miraculous control inherent with Fly-By-Wire avionics .
My conclusion here is that the future belongs to those who dare to challenge orthodoxy , and conventional wisdom !
I sign off with " Keep the Edge ! " .
..........The " Professor "
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Addendum
Check out The National Interest ,
July 21 , 2018 issue in regards to
the RAF's F/A Tempest aircraft . It
features a visor addition to allow
the pilot to see " through " the
plane to the ground & surrounding
airspace . It is , of course , VTOL .
Victory , at any cost , even the unorthodox solutions !....P.M.