[Professor Mega-Mind (OP)]

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.

[alancalverd]

 

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)

[Professor Mega-Mind (OP)]

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.

[alancalverd]

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.

[Professor Mega-Mind (OP)]

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.

[Kryptid]

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.

[alancalverd]

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.

[Professor Mega-Mind (OP)]

                    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.

[alancalverd]

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.

[Professor Mega-Mind (OP)]

             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 "

[Professor Mega-Mind (OP)]

                     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.