If the Hughes H-1 would have been made into a fighter...

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After some research, I realized I was assuming wrong information on empty weight. I originally assumed the empty weight included armament weight. Apparently it doesn't. I decided to compare gross weight, which is always dangerous since aircraft tend to vary in fuel weight. Here's a more detailed breakdown in what I perceive as a fighter version of the H-1 in 1939.

H-1 extended wings – 4097 lbs (Aluminum wings may have weight less or more, I suspect less)
Airframe modification for military stress levels – 300 lbs
Delta R-1830 weight – 200 lbs
Instrument/radio – 100 lbs (approx. P-40B)
Armor/BP glass – 93 lbs (P-40B)

Empty weight – 4790 lbs

Armament including installation-two .50 cals, two .30 cals – 197 lbs (P-40B)
Oxygen – 20 lbs (P-40)
Miscellaneous – 100 lbs

Basic weight – 5107 lbs

Pilot – 200 lbs
Usable oil – 68 lbs (F4F-3)
Ammo (.30 cal, .50 cal) - 165 lbs (P-40B)
Fuel – 720 lbs (120 gal)

Gross weight – 6260 lbs (I think this is a conservative number.)

For a reasonableness check in comparison to gross weight of contemporary aircraft with similar engines:

P-35A – 6118 lbs
P-36C – 5800 lbs
F2A-2 – 5942 lbs (Wright R-1820)

So the weight passes the smell test.

H-1 fighter Performance calculated at this weight
Gross weight – 6260 lbs
SL 330 mph
Max speed 375-380 mph at 22k
p/w - .19 hp/lb
Wing loading – 32.8 lb/sqft

Spitfire Mark I
Gross weight – 6200 lbs
SL speed – 285-290 mph
Max speed 362 mph at 18.5k
p/w - .17 hp/lb
Wing loading – 25.6 lb/sqft

The H-1 fighter would have a significant speed advantage at all altitudes, acceleration, and, probably, dive (cleaner) over the Spit. It would probably have trouble in maneuvering and climb.

Bf-109E
Gross weight – 5520 lbs
SL speed – est. 290 mph
Max speed – 357 mph at 20k
p/w - .21 hp/lb
Wing loading – 31.3 lbs/sqft

The H-1 fighter would have a significant speed advantage at all altitudes and probably dive advantage (cleaner) over the Bf-109. Bf-109 would have acceleration and probably climb advantage.

P-40B
Gross weight – 7335 lbs
Max speed – 353 mph at 15k
p/w - .14
Wing loading 31.1 lbs/sqft

A6M model 21
Gross weight – 5314 lbs
SL speed – 277 mph
Max speed – 331 mph
p/w - .18 hp/lb
Wing loading – 22 lbs/sqft

The H-1 fighter would have a overpowering speed advantage at all altitudes and dive advantage (cleaner) over the Zero. Like all other fighters, don't dogfight or climb against a Japanese fighter.

what weight are you using for the engine? please note that the R-1839-76 was somewhat heavier than the non- 2 stage R-1830 engines and that the intercooler may not be part of the listed dry weight. What weight are you allowing for the propeller?
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P&W list weight of the R-1830 as 1,162 to 1467 lbs. Wikipedia states that the weight of the R-1535 as 1087 lbs so weight can go from 75 lb increase to 380 lbs. I chose 200 lb increase and I could be wrong as I don't have detailed weight on various configurations of the R-1830. I think the fact that similar aircraft with cantilever wings, retracting landing gear and similar engine and meeting military requirements shows that the H-1 could be developed into a military aircraft within the same weight constraints. I threw in another 100 lbs miscellaneous to cover unknowns.



The AF museum site states that the max speed of the XP-34 with the R-1830 of 308 mph did not warrant a contract.

Factsheets : Wedell-Williams XP-34

308 mph at 900 hp is slow. Since weight impact is low at high speeds, there were other problems with this design other than beefing up for military applications.

Another thought is that the AAF was switching thoughts to liquid cooled engines at this time. I would have thought they would be all over the H-1, especially after the cross country flight, in spite of the snub. In the 1939 competition, there were no air cooled designs.

The XP-34 was based off the Wedell-Williams model 45, not the model 44. The model 45 had both a cantilever wing and retractable landing gear.
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Okay, just got a bit misdirected.


Shortround6 said:
WE also know that there was a design study concerning turning the Wedell-Williams 44 racer into a fighter just a few years before,
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Strangely enough the XP-34 was supposed to be powered by the same basic engine as the Hughes and even stranger, no production version of the engine was ever rated at more than about 900hp.
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The XP-34 was supposed to have the 900 hp engine. Hughes boosted the 700 hp engine to 1000 hp by tuning it on 100 octane fuel. I think the R-1830 stopped advanced work on the R-1535, just as R-2800 development stymied advanced work on the R-1830.



FLYBOY said:
Actually if the plane was designed to just go fast, straight and level then if anything it would have been built lighter and "weaker" as it was not going to have any stress loads applied to it
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That's what I was trying to say.


I think I addressed all those issues.

You still haven't considered military equipment, stress analysis on the current airframe and what it would take to structurally enhance the aircraft to accept the required equipment and extra weight and to perform at combat Gs. Also consider range...
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I think I did. I am not a stress guy nor am I a structures engineer, and I don't know what levels the H-1 was originally designed to, so I can only guess what it would take to make a plane like the H-1 into a military aircraft. However, I do have an indication that my assumptions are reasonable and that is similar aircraft, in a similar time period, were developed into military aircraft. The P-35 and P-36 both were military aircraft delivered at about the same gross weight I identified for a fighter version of the H-1. As you may well know, qualification by similarity is a accepted criteria for military hardware and, while I am not arguing about qualing an aircraft, I am claiming similarity in justifying my estimation.

I think by the time you're done making the aircraft a true military aircraft, you're going to need another 500 HP to stay competitive.
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My point is that the H-1 had so much speed advantage that it could absorb a lot of modifications and still be a superior performer, certainly in airspeed. The H-1 did 352 mph at low level. The Spitfire Mark I did maybe 290 mph. I have shown that you could take the H-1, increase the weight to the same as the Spitfire I, put a big wing on it and increase fuselage diameter to fit a more powerful R-1830 and it would still be 30-40 mph faster at low level. In addition, it would maintain a speed advantage to 22k and probably higher. It was cleaner than any other aircraft of the time and, like the P-51, cleanliness in itself is a big advantage.
 
davparlr said:
I think I did. I am not a stress guy nor am I a structures engineer, and I don't know what levels the H-1 was originally designed to, so I can only guess what it would take to make a plane like the H-1 into a military aircraft.
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Under the old CAA regs I would guess the aircraft was only stressed to 3.5+ gs, 1.5-. I think to make this aircraft "combat worthy" you're looking at 9+Gs, 3-Gs. You'd have to stress the aircraft and then consider the equipment "bolted" to the airframe and compile that load. Like you, I'm not a stress engineer but I have worked with a few and seen the results of their work. I've seen sheet metal parts double in thickness and weight just so an extra G could be picked up on the aircraft. I still think you're looking at a substantial weight gain if the H2 was made into a fighter.
 
It is quite possible that the H-1 was stressed for 3.8 "G"s with a 1.5 safety factor for an ultimate strength of of 5.7. This would probably have satisfied the inspectors of the time for an airworthiness certificate. This might be for the long wing version full of fuel. The short wing version lightly loaded would of course have a higher "g" rating.

When doing these hypothetical engine swaps it is nice to consider everything. The the weights usually given for the R-1830 are for engines with either a single speed supercharger or a two speed supercharger. Adding a second supercharger (the 1st stage of the 2 stage system used on the Wildcat) is obviously going to add weight. Weight for the Version used in the Wildcat is 1565lbs. This may not include the intercooler.
Other weights to consider are the propeller. The Hughes used a rather small two blade propeller. this may have been perfectly adequate for 1000hp at near sea level for a record run. It may have been adequate for 500-700hp at altitude for the cross country record run. It would not be adequate for the 1000hp at 20,000ft plus. A 3 bladed propeller would be needed. Note that the propeller used on the F4F-3 was about 50lbs heavier than the 3 bladed propeller used on early Buffaloes.
A different cowl would almost certainly be needed. Photos of the H-1 don't show any adjustable air outlets. While a fixed slot can be configured for low drag in one condition getting adequate cooling in a high powered climb (which the record aircraft didn't have to do) while not having excessive drag for high speed flight usually calls for cowl flaps of some sort. A larger oil system might also be needed but the one sized for the crosss country flight might do the trick, perhaps just a slightly larger oil cooler.
starter system might be just a bit heavier or not, Military airplane would probably require a larger generator. Exhaust system will be a few pounds heavier, the R-1830 is larger in diameter even if the pipes don't have to be any larger in cross section and dry weights of engines do not include exhaust pipes/systems.

As for armament, you have not included any weight for the beefing up of local structure to handle the recoil loads. this is not usually broken out as a separate weight in weight charts but it is real. also real are the weights of the gun mounts, ammo boxes, chutes and gun heaters, 30% more weight than the guns and ammo might be fair.
Weight of ammo-.30 cal ammo weighs about 6 pounds per 100rounds. .50 cal ammo is close to 30 pounds per 100 rounds. I personally believe the P-40B carried too much .50 cal ammo at 380 rounds per gun but I think your 165lb total is a little light. 500rpg of .30 cal will give you about the 65 pounds but 100 pounds of .50 cal is only going to give you about 167 rounds per .50 cal MG. you can always trade some .30 ammo for .50 ammo. with wing guns you have about 17 seconds firing time for the .50s and a bit over 25 seconds of firing time on the .30s with 500rpg.
All guns will have to be in the wings unless the fuselage is made really fat which kind of defeats the whole purpose. The P-40 carried a ridicules amount of .50 cal ammo considering that the .50 didn't take to synchronization all that well and the rate of fire slowed to around 450rpm.
Does the H-1 have any potential beyond 1940-41 or will it be a dead end design, unable to mount heavier armament, radios and electronics and stuck with a small internal fuel capacity?
 

I would use the H-1 only as a concept prototype. Since there were no production hardware built, redesigning from the start for military operations would be most efficient, especially since the fuselage would require at least a 2" radius increase, so, performance would be built-in and not "bolting on".

The P-35A and P-36C were both low wing monoplanes with retractable gear, R-1830 engine, and two 50 cals and two 30 cals (for the P-35. The P-36 had one 50cal and three 30cal.) and both met the military "combat worthy" criteria and grossed out at a similar weight as my proposed H-1 fighter. I see no problem for Hughes building this aircraft to meet those weight goals.


Shortround6 said:
When doing these hypothetical engine swaps it is nice to consider everything.
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If everything was available to us, we would not have to argue.


We don't know enough about any of these aircraft to make a detailed analysis. We can, however, compare to similar aircraft. The P-36C is an aircraft accepted by the Army and saw combat. It is a modern aircraft with standard aluminum construction, P&W 1830-17 engine with three bladed, variable pitch propeller, one 50 cal and three 30 cal machine guns, and retractable landing gear. As delivered operational ready, it has a gross weight of 5800 lbs. Add three hundred pounds for the heaviest R-1830 and 93 lbs for P-40 level armor and the gross weight would be 6193 lbs, still 67 lbs below the gross weight I identified for the H-1 fighter. While weight will still vary, it will have negligible affect on performance.



Agreed, and there would be some risk in performance but there was a lot of data on cowl design. Again, all these things would have been included the weight of the P-35 and P-36 aircraft.


Again, these would have been in the P-36/P-35 weight (maybe not heaters). I think all the installation weight, about 75 lbs/50 cal, includes the items you mention. I couldn't find the weight of an AN/M2 gun but I believe it is lighter than 75 lbs. The weight identified in "America's Hundred Thousand" specifically calls out 50 cal "installation" for P-40.


I just used the P-40 because it was the only AAF aircraft in 1939 range that I had data on.

It baffles me that there is such an argument against the US building this aircraft when both the Spitfire I and Bf-109E met all the fighter requirements at this weight (the Bf much lighter) and yet with engines, with cooling, that are heavier than the H-1s engine could possibly be. I think to assert that the US aircraft industry could not build an airframe equivalent to these aircraft is incorrect.

If I was the program manager for the H-1 fighter in 1937, I would be very confident, with a real aero guy verifying my data, in putting together and presenting a PDR (Preliminary Design Review validating requirements, required before detail design can begin) with the following bullets.

1) Low risk to airframe design and weight based on similarity to P-35 and P-36 using standard construction practices.
2) Low to medium risk on performance based on actual flight performance demonstrator (H-1). Some risk due to impact of dimensional, outline modifications, and other changes for operational requirements.
3) Low to medium risk for manufacture due to new flush rivet machine and fit criteria.
4) Cost, always medium to high risk for military development
5) Schedule is low risk for two years to production

Does the H-1 have any potential beyond 1940-41 or will it be a dead end design, unable to mount heavier armament, radios and electronics and stuck with a small internal fuel capacity?
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This is a good question. While the H-1 fighter that I think it could be,, would have been very helpful to the Allies in the 1939 to 1940 time frame, especially the Brits during the BoB where it would have a considerable speed advantage over the Bf-109E, I don't think it really fit into the AAF philosophy, it was too light. In addition, by late '40 it would, without improvements to the R-1830, be regulated to second class citizen such as the P-40 and P-39, although much better performing. Water injection would have helped boost power but I don't think that was available until maybe late '43. Another answer would have been to incorporate turbo supercharger like the P-38. There would have been room behind the engine and could have provided much better high altitude performance. That probably would have been trouble, though. No, I think the only thing that would keep the plane competitive would be to make a major redesign, i.e., a whole new plane, to handle the R-2800, but there would have been no pressure to do that. So, I guess I agree.
 
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Does the H-1 have any potential beyond 1940-41 or will it be a dead end design, unable to mount heavier armament, radios and electronics and stuck with a small internal fuel capacity?
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I think it would have been a dead end, but one that remained competitive (somewhat like the A6M) to the end of the war at a low unit cost, suitable for export to the Chinese, Indian, Australian, Russian and other allied air forces much like the P-40 and P-39 were.
 

Speed may be a be effected slightly but the effect on climb will be grater.


THe US aircraft industry might very well have been able to build such an airframe. The question is whither the AAF would have bought it. Neither plane was stressed to the same level as standard AAF requirements.
Neither plane carried the same fuel load as the American planes and the two .50 cal and two .30cal armament with ammo was as heavy or heavier than the armament installed in either plane. Both planes may have used lighter landing gear than the US planes quoted.

I don't know if there was a minimum landing speed or minimum take-off distance in any of the Army requests. This would affect things like wing loading and thus wing area.

See the XP-41, XP-42, and Vultee Vanguard (P-66) and the P-43 for other American fighters powered by the R-1830. And attempts at streamlining.
Data is almost impossible to come by but there was a version of the XP-41 (if not the XP-41 itself, accounts are contradictory) and a factory demonstrator Hawk powered by an early version of the two stage R-1830.
 
I would have to look at the airframe analysis to make any judgments about requirements for 7-8g limit load.. I would first look at the design aerodynamic loads and performance envelope. A pylon racer would be designed at least to a 3-5g load and a lot of asymmetrical load - namely rudder, elevator and aileron inputs around the pylon.

What I'm suggesting is twofold.

First the target gross weight for stress analysis purposes has the be conceptualized (including armament, fuel, etc) -

Second the design performance attributes -

If I was looking at the H-1 'as is' I would first look at presumed loads for high G dive pullout and max roll at high speed. I suspect the vertical stabilizer was designed for low speed aerodynamic control for the design max torque of engine, but the diving roll asymmetrical load would be the limiting factor on the aft structure and the fore/aft beam cap sizing.

The high g pullout would be the limiting case on the wing spar design.

I have no clue regarding weight increase for a re-design but the primary increase would be spar and longeron cross sectional area first, the carry through structure for the vertical stabilizer to fuselage and wing spar to fuelage next, then engine mount and general shear panel thickness sizing analysis next.
 
Shortround6 said:
Speed may be a be effected slightly but the effect on climb will be grater.
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Yes, but we don't know what the climb rate was to start with, so, it's a guess.

THe US aircraft industry might very well have been able to build such an airframe. The question is whither the AAF would have bought it. Neither plane was stressed to the same level as standard AAF requirements.
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This is true for the Spit, but I think it has been reported on this site that the Bf-109 was stress tested to 12 "g"s, which would have made 8 "g" operational.



I used 120 gallons, which is 20 more than the Bf-109 and equal to the P-39, but basically your statement is correct, AAF fighters carried more fuel. As for the armament weight and landing gear, the DB 601 and Merlin III with cooling were both close to 2-300 pounds heavier than the R-1830.



All of these aircraft were quite bulky in design unlike the Spitfire, Bf-109, and H-1, which basically tried to hide the fuselage behind the bulk of the engine. However the Vanguard, P-66 and the XP-42 do show some potential. The Vanguard, with its streamline cowling was capable of 358 mph at 15.6 k with an engine that produced 900 hp at 15.4k, the P-66, similar to the Vanguard but using a conventional cowling, was capable of 340 mph at 15.1k with the same engine. The XP-42, with a conventional cowling and an engine that produced 1000 hp at 14.5k, was capable of 343 mph (probably at 14.5k). Now if we take these planes an slim them down to the size of a tightly cowled engine, lower the cockpit bow by 3 to 4 inches to make compatible to P-51A (which is, by the way only about one inch higher than the H-1), put an engine in that makes 1000 hp at 19k, and I think you can see that these planes could be quite formidable. The P-41/43 were also very bulky and had turbo-superchargers.

A side note here is that all of those aircraft could have possibly been upgraded to the R-2800, which would definitely have been a superior advantage to the H-1. Actually the P-43 eventually grew into the P-47. The P-66 sure looks like a straight wing F4U but I cannot find a connection.

Richard Palmer, who helped Hughes design the H-1, joined Vultee and designed the P-66 based on the H-1. There must have been recognition that the Army wanted bigger aircraft than the typical European fighters as the P-66 has about a foot larger diameter than the H-1, which was about the size of the Bf-109. An additional foot would make a significant increase in frontal area for the P-66. My proposed fighter would look a lot like the P-66, only slimmer (one foot less fuselage diameter), lower canopy and lower aft canopy struture, and smaller vertical stabilizer since smaller diameter up front will reduce need for vertical stabilization area). See below.

The proposed H-1 fighter would have been more along the lines of the Spitfire and Bf-109, small and agile and fast, and, with its superior speed and altitude performance, would have been very useful to the Brits and Americans in BoB, Africa and Pacific. Without an influx of money to push the R-1830 engine, it would have limited growth potential, and would not have been favored by AAF.
 

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If your H-1 fighter were built I think it might have remained competitive through eventually being re-engined with the R-2000 (which is just an R-1830 with improved cylinders)
 
Clay_Allison said:
If your H-1 fighter were built I think it might have remained competitive through eventually being re-engined with the R-2000 (which is just an R-1830 with improved cylinders)
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I think you are right. It appears in the correct time span an seems to have provided equal horsepower to the Spitfire through the Mark V and the Bf-109G. I just don't think the Army AF was interested in point defense and tactical fighters like the spitfire and Bf-109. It is too bad, it could have remove some stress from the Merlin line.
 
Clay_Allison said:
If your H-1 fighter were built I think it might have remained competitive through eventually being re-engined with the R-2000 (which is just an R-1830 with improved cylinders)
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I think you are right. It appears in the correct time span an seems to have provided equal horsepower to the Spitfire through the Mark V and the Bf-109G. I just don't think the Army AF was interested in point defense and tactical fighters like the spitfire and Bf-109. It is too bad, it could have remove some stress from the Merlin line.
 

Point defense could have been helpful all over the Pacific Theater, opposing the wide ranging raids from the IJN and JAAF at every turn.
 

Unfortunately, I am convinced that You have not yet succeeded to prove this assumption beeing correct. How big is the new wing? What is the difference in drag related to the bigger fuselage? What was the original powerlevel at the H-1´s record flights? Remember, it took basically a simple Bf-109D airframe very little to achieve a low level record speed of 610 km/h. On 11 November 1937 the Bf 109 V13 flown by Messerschmitt's Chief pilot Dr. Hermann Wurster, and powered by an 1,650 hp (1,230 kW) DB 601R racing engine set a new world air speed record for Landplanes with piston engines to 610.55 km/h (379.38 mph) at low level and won the title for Germany for the first time. The V-13´s modification was the Db-601R engine, a special treated surface and the removement of equipment and weapons. Nevertheless, the same Bf-109D but in an operational condition was unable to hit 300 mp/h at SL with a normal rated engine.
As far as I know, the H-1´s special engine was also tuned from 700 hp to over 1000 hp, altough the exact powerlevel at the flights are still unkown to day.

The wing area was just 138 ft^2 in the original design. The adjusted bigger wing area of Your design is around 190 ft^2. This alone translates into 38.5% more wing area.
With a 1200 hp rated engine at Sealevel and the given increase in wing area, my physics show no realistic probability to exceed a speed of 300 mp/h at Sea level. Actually, with this increase in wing area, You would need to pull at least 1330 hp out of the engine to make 330 mp/h at SL plausible. With the same 1000 hp engine, the H-1 would have been hardly pressed to hit 250 mp/h at SL with the bigger wings, everything else staying identical to the H-1 Special. And this does not include the increased drag caused by the bigger diameter fuselage, equipment, raised canopy or gunports. All included, a top speed of ca. 290 mp/h seems more realistic to me (there is some likelyhood that more exhoust thrust may be generated). This also puts the H-1 closer along the lines of the performance drops known from the Bf-109D and Spitfire.
 
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Dick Palmer, principal designer of the H-1, was a family friend. I knew him fairly well, talked to him at length about the H1. He told me the bird was almost ready to fly before Hughes let him know that he, Hughes, was going to fly it. Dick was worried. He thought Hughes was competent enough, but it was a new design, and Hughes was signing the pay checks, so Dick both assumed and hoped Hughes was going to have a professional test pilot do the flying.
I asked him if it was a difficult or dangerous plane to fly. He thought not. Especially with the X-country long wings. He specifically said stalls were NOT violent, abrupt or in any way unusual.
If I remember correctly, the landing gear was unusual, all the shock absorbing was done by the tires. Dick had saved weight in the gear, but I don't think springless, shockless gear would work for a military airplane.
For what it's worth, I also asked him if the H1 could have been made into a military airplane. Answer: "That was the idea."
I've always thought the H1 may be the most beautiful machine of any kind ever made by anyone. I have spent many hours just looking at in the old Smithsonian. I was sorry I never got to see the Wright replica, and even sorrier that it and Wright crashed.
 
Great info Tom.

If I'm not mistaken I think the Mosquito's MLG is basically two tubes with rubber pucks in the middle taking up the shock of landing. I also think the same set up i used on the Avro Anson.
 
Let me re-phrase my question. What if the H-1 had been designed around the Allison V-1710 from the very beginning? Less frontal area, potentially an even cleaner airframe. It would have been a much better prospect for a fighter if it already had a desirable power plant, rather than the need for an iffy engine swap that would have unpredictable results.

With the lines and the shape of the plane already determined, all that would remain is stressing it, putting a standard Allison (rather than an overboosted racing engine that might have been pushed to 1600 horses for the speed record) in it and hanging guns, armor and self sealing tanks on it, the exact same process that the Spit and the 109 had to go through.
 
Going back briefly to the U/C. The Gloster Gladiator had the springs inside the wheel and nothing at all on the legs, sounds similar to the H-1 set up and that was on a military plane, so it could have been ok in that regard
 
did the Gladiator have fixed or retracting gear?

Also, bump for my last question.
 
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