[What If] Bugatti P-100 as a fighter plane?

Turning the P100 into a fighter would be analogous to turning an F1 racer into a road going sports car - which is to say, totally impractical. The value of such designs lies not in their potential for conversion into everyday models, but as test beds for technologies that can then be bolted on to existing, practical designs. Look at all the F1 innovations we now take for granted not only in performance cars but common passenger vehicles. Likewise, Mitchell undoubtedly learned a lot from designing his Schneider Trophy racers that went into the Spitfire. Racing improves the breed, but racehorses are one trick ponies.

SPEKTRE76 said:

What if you could turn the Bugatti P-100 into a fighterplane? What would you change about it and what guns would you give it or other armament?

Mre personaly, I'd give it (for first entry into the war in 1940):

• 'Tri-blade' contra prop

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  Unreliable and unproved technology at the time, unlikely to be accepted into service and a maintenance nightmare if it does get there. To put things into consideration, the RAF barely got constant-speed props into service for its fighters by 1940.
  
  

  SPEKTRE76 said:

  [*]RR Packard Merlin V-1650-7

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  Not available until late 1942/early 1943, so you'd need to delay entry into service by a couple of years.
  
  

  SPEKTRE76 said:

  [*]2 x Hispano 20mm cannons in the nose 200rds each (think Me-262)

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  Hispano "fired from a rear sear (open bolt) and could not be synchronised" (quoting Tony Williams). You'd need to change the gun to electrically primed ammunition to get it to work to fire through the prop arc. Contra-props would hamper rate of fire as well.
  
  Hispano is long - over 8t ft - and very heavy. The bare gun with no mounts, feeds or ammunition weighed almost 50 kg/110 lbs. Adding 200 rds of ammunition per gun would bring total installed weight to just short of 550 lbs, all in the nose.
  
  

  SPEKTRE76 said:

  [*]2 x .50CAL wing guns mounted mid wing just outside teh landing gear pivot 350rds each

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  You'll need to shift the outer wing tanks to make room for the .50s and that much ammunition. So, you're probably going to have to fit fuselage tanks or sacrifice range.
  
  Plus, you need to compensate for the extra 315 lbs that the .50s and all that ammo would add.
  
  

  SPEKTRE76 said:

  [*]Can carry 1 x 250lbs bomb or 2 x HVAR rockets

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  250 lbs bombs are fine in 1940 (although few fighters carried bombs at the time). HVARs aren't available until 1944 as well.

Basically, to turn the P.100 into a worthwhile fighter, you'd have to completely rework it.

1. Structure. P.100 was primarily made of wood/balsa and had a very light structure. While wood aircraft were serviceable and useful in WW2 (Mosquito, LaGG-1/-3/La-5) you'd probably want a much more robust metal structure for a Western service fighter. Weight might actually come down with an aluminium monocoque, but surface finish drag will go up (particularly with 1939/1940 manufacturing techniques).

2. Engine. You'd need to replace the two 540-560 lb Type 50B engines with a single 1350 lb Merlin. That means a complete revision of cooling, plumbing and aircraft balance arrangements, as well as the prop shaft. You'll probably need to revise the cooling intakes as well. None of that's a simple job.

3. Prop. Contra-props are never going to get accepted into service in a 1940 fighter. You'd probably need a larger three blade prop. Reduce complexity and maybe save some weight, but may take away some performance.

4. Armament. With your 2 x 20 mm and 2 x .50 cal set-up, you'd add at least 860 lbs to basic weight. There's not enough room in the nose or the outer part of the wings for the Hispanos and they cant be synched to fire through the prop. You might get .50 cals in the nose, but to get them in the wings you're going to have to delete some of the wing outer fuel tank capacity.

5. Fuel system. You need to fit self sealing tanks. Depending on type, this is probably going to cost you 10-15% of total fuel capacity. Self-sealing tanks will add about 80-100 lbs in weight.

6. Armour. You'd need to fit pilot armour and armour for the fuel tanks and ammunition boxes, probably for the ending as well, considering its rear mounted. You'll also want an armoured, optically flat windscreen, so the pilot's vision isn't distorted while aiming. Minimum 120 lbs, more realistically 180 lbs in extra weight.

7. Radios, D/F and IFF. You need to find space for short-range and long-range militray radios, as well as a direction finding loop and an IFF system. US WW2 radio system weight in at about 100 lbs. D/F and IFF added about 45 lbs as well.

8. Cockpit. The pilot is almost completely blind in the rear quarter and mostly blind with downward search view. You'll need to rework the seating and cockpit positions to give the pilot a better search and aiming view.

9. Gunsights and gun camera. Add 20 lbs for the two.

The way I see it, you're probably better starting off from scratch. To bring the P100 up to military spec, you'd need to gut the design and add at a minimum about 1600 lbs in weight (to the original 3000 lbs).

Changing to a single prop introduces a LOT of torque that was designed OUT, necessitating a LOT of change, especially to the fin and rudder area. The plane is too small for a Merlin ... there would be NO PLACE for a pilot. It weighed only about 500 pounds more than a Cessna 172! The landing gear would never be able to cope with a Merlin prop. The entire airframe is WAY too small for a Merlin, Allison, Hispano-Suiza, or whatever in a big-displacement V-12.

C'mon, get real. This will never be a fighter and hasn't actually flown yet. I think it would fly, but not with a major off-the-cuff redesign without ever looking at the ramifications of the proposed changes.

The empty weight was 3,085 pounds and Merlin is 1,400+ pounds all by itself without the radiator. The Bugatti Type 50 engine was supercharged to eventually make 250 HP in cars, but the 50P was reported to have 450 HP. How many engines YOU know of can double their power output with no change in displacement? And still remain reliable? Huh? The Merlin did but I wonder did the Bugatti 50P engine got the same engineering attention the Merlin got? Ettore Bugatti didn't HAVE sir Stanley Hooker to design a supercharger or intake track and wasn't well placed in the government to get 130/150 fuel when the 100p was designed.

If it had 250 HP each the sum would be 500 HP, and a 500 HP Cessna 172 would definitely perform better ... but 500 mph ... I have my doubts about this thing from the start, but think it would be fast for the size and real power. Bugattis aren't usually associated with slow slugs.

When and if the new build unit flies and survives, we'll hear about the performance and flight characteristics ... with the benefit of modern knowledge. I'd bet you almost anything that the props used on the new one will be better by a considerable margin than the props on the original. I'd bet the finish is better, too, assuming some competence.

The potential for power HAS to be better. A 4.9 liter engine today can produce prodigious power if done correctly. Mine did. I got 650 HP from a 5.0 liter V-8 easily. I don't still have it and wish I did ... but my 5.6 liter Camaro makes 325 HP and has done so for 70,000 miles. Last dyno was 326.5 HP at the rear wheels. So the power is easily possible, even unsupercharged.

Was it possible before WWII on pre-WWII gasoline? I don't know and will not hazard a guess. But I think for an aircraft engine turning 2,500 - 2,800 rpm ... no. I don't know the specs for the Bugatti type 50P engine, but I suspect it was 5,000+ rpm and would not want to be flying that before WWII if I wanted to live. The metalurgy wasn't that well known for durability at those revs ... at LEAST for a service fighter.