Improve That Design: How Aircraft Could Have Been Made Better

[Shortround6]

Why did the Germans have such an obsession with mounting their superchargers on a 90-degree angle? There was a guy who has a channel on YouTube named Greg called "Greg's Airplanes and Automobiles", and he was also curious about that.

So they could fire a cannon down through the engine and out the prop hub.

Supercharger has to go someplace, either off to one side or the other or push it down below the cannon or maybe even lay it flat ( I don't think anybody did that).
Hispanos didn't use a very big supercharger and they pushed it down low on the engine and the cannon went over the top.

If you want to use a bigger supercharger you have to figure out where to put it.

 

[pinsog]

"If I may ask, how did you compute the differences in speed due to different horsepower figures?"
New hp/old hp = X Cube root of X multiplied times old speed

1200 hp/1000 hp = 1.2. Cube root of 1.2 is 1.06265857. 1.06265857 x 330 mph (at 19000) = 350 mph.


"The shorter nacelles (R-1820) allowed more forward visibility than the longer R-1830. Performance was still adequate despite the R-1830 being thinner, and it was felt that it the R-1820 was simpler and easier to maintain."

The lengthened nacelles doesnt refer to how much the engine sticks out the front. Look at the short nosed F5F, the engine nacelles stop midwingand then the long nose F5F the nacelles extend past the rear edge of the wing. The P&W 1830 was never considered, only the P&W 1535 which wasn't going to be supported by P&W, so they went with the Wright 1820, best guess is because it was identical in weight to the 1535.

See the difference?

 

[Shortround6]

There was supposed to be a two stage version of the R-1535 but it never got built. So yes, the R-1820 was the easiest engine to use as a substitute, at least to get something flying.

 

[tyrodtom]

So they could fire a cannon down through the engine and out the prop hub.

Supercharger has to go someplace, either off to one side or the other or push it down below the cannon or maybe even lay it flat ( I don't think anybody did that).
Hispanos didn't use a very big supercharger and they pushed it down low on the engine and the cannon went over the top.

View attachment 541368
If you want to use a bigger supercharger you have to figure out where to put it.

I notice the exhaust and intake is both on the outside of the V, leaving the inside for the cannon.
Maybe one of the reasons the Hispano was such a underperformer HP wise.
The intake passages to the intake valve had to be pretty convoluted through that head from the outside

 

[GrauGeist]

The "long nose" XF5F was actually the Army's XP-50. The longer nose on the XP-50 was for the nose-gear.

There was only one of each ever built and they both used the Wright R-1820.
XF5F: R-1820-40/42
XP-50: R-1820-67/69 turbosupercharged (which is why it had larger nacelles than the XF5F)

 

[pinsog]

The "long nose" XF5F was actually the Army's XP-50. The longer nose on the XP-50 was for the nose-gear.

There was only one of each ever built and they both used the Wright R-1820.
XF5F: R-1820-40/42
XP-50: R-1820-67/69 turbosupercharged (which is why it had larger nacelles than the XF5F)

No sir. The XF5F was rebuilt from a short nose short nacelle aircraft into a long nose long nacelle aircraft.

The XP50 had a tricycle landing gear.

You are correct that the XP50 was turbocharged and the XF5F was not, even when it had long nacelles.

 

[Shortround6]

Unfortunately the longer nose, longer nacelles, prop spinners and a few other changes still didn't get the drag low enough get the performance where they wanted.

 

[Shortround6]

I notice the exhaust and intake is both on the outside of the V, leaving the inside for the cannon.
Maybe one of the reasons the Hispano was such a underperformer HP wise.
The intake passages to the intake valve had to be pretty convoluted through that head from the outside

There were a lot of reasons for the Hispano being an underperformer in 1939-40, one of them is that it was an engine from the late 20s that "inherited" some of it's design features (and design limits, like bore spacing) from the WW I Hispano V-8s. One source claims Hispano superchargers would get so hot they would blister the paint on the supercharger. Poor paint or hot supercharger

Point is that if you tried to mount a Merlin supercharger on the back of the engine it would hit the bottom of the cannon. The Germans ran the intake air on the inside of the V. the German guns were not bolted to the engine but the barrels fit in a 70mm ID tube that ran from the back of the engine to the reduction gear. the whole cannon breach and feed system was hanging just in back of the engine about where you would want the supercharger to go.

 

[pinsog]

Unfortunately the longer nose, longer nacelles, prop spinners and a few other changes still didn't get the drag low enough get the performance where they wanted.

They needed more power. If they had used turbocharged Wright 1820's it would have probably equaled an early P38 in top speed and clobbered it in climb.

Look at the XF5F test vs a P38E. At 20,000 feet a P38E was doing 352 mph on 750 hp per engine. Top speed of an XF5F at 20,000 feet was 352 mph. Those 2 speed Wright's couldn't have been putting out over 750 hp. My guess is they were about 700 hp each. I think an XF5F and a P38E had about the same drag.

 

[Zipper730]

"If I may ask, how did you compute the differences in speed due to different horsepower figures?"
New hp/old hp = X Cube root of X multiplied times old speed

1200 hp/1000 hp = 1.2. Cube root of 1.2 is 1.06265857. 1.06265857 x 330 mph (at 19000) = 350 mph.

Oh, okay: I get it now

The lengthened nacelles doesnt refer to how much the engine sticks out the front. Look at the short nosed F5F, the engine nacelles stop midwingand then the long nose F5F the nacelles extend past the rear edge of the wing.

So, it has to do with the nacelle extending further rearward...

The P&W 1830 was never considered

Actually, I have a book on the plane and I thought I remembered that it was looked at very early on...

 

[pinsog]

Oh, okay: I get it now
So, it has to do with the nacelle extending further rearward...
Actually, I have a book on the plane and I thought I remembered that it was looked at very early on...

Correct on the nacelle extending rearward. I have the same book, the first engine they considered was a P&W 1535 but as Shortround said, they decided not to do a 2 stage version. The Wright 1820 was the same weight, I think that is why they chose it

 

[pinsog]

A P38E does 340.5 mph on 1150 hp per engine at 5000 feet
The XF5F did 326 mph on 1000 hp per engine at 4500 feet.

Give the XF5F 1150 per engine and

1150/1000 = 1.15. Cube root of 1.15 is 1.047689. 1.047689 X 326 = 341.5 mph

Same hp, same speed, 2 different altitudes. They should have turbocharged the XF5F and they could have, essentially, had a carrier based P38E that weighed 3000 pounds less, after adding armor and seal sealing tanks, and was 10 feet shorter and 10 foot less wingspan.

 

[Zipper730]

1150/1000 = 1.15. Square root of 1.15 is 1.047689. 1.047689 X 326 = 341.5 mph

I thought you were supposed to use cube-root, but the numbers look okay.

 

[pinsog]

I thought you were supposed to use cube-root, but the numbers look okay.

Your correct. I used cube root but typed square root. I'm going to edit my previous post

 

[tomo pauk]

Actually, I gave three allowances for specifications

1. The existing specification: Basically, the idea would be working within the existing specification, but you could modify or change anything within the boundary of it.
2. A different winner: Sometimes the problem wasn't the design so much as the winner to the contender: While way after WWII, many feel the YF-23 should have won over the YF-22, for example.
3. A more realistic/practical specification: Basically the specifications are made more realistic to allow a practical design to be developed, an example would be the He-177 having 4 x DB-601's instead of 2 x DB-606's, or simply not being designed as a dive-bomber.

Thank you.
Per #1, seems my idea of Fw 190 + DB 601/605 works, so does the high-wing Ju 88, as well as small+light fuselage B-26.
Not sure for Fury and Gladiator being designed as monoplanes?

This is an idea that's interesting. Do you have any documentation on this suggestion?

Download: link

A DB-603 with a turbo would have given it some great high altitude performance. When you say the idea was beaten to death -- I'm not sure what you mean, however.

Beaten to death: almost every alternative Fw 190 discussed has DB 603A in the nose by some time 1943.

 

[Shortround6]

Not sure for Fury and Gladiator being designed as monoplanes?

The trouble is, even if it happened, you don't get anything really useable and you don't get a lot of good design experience, except perhaps what not to do
Supermarine 224

Fixed gear, thick wing, open cockpit of early Bristol 133

later

No flaps or flaps added later? Landing gear makes a P-35 look good. Why the fuselage is that fat for the engine it used or what had to go in it?
The Gladiator was never intended to be a "standard" fighter. It was another of the all too many "we need an interim plane NOW, to equip the new squadrons with while we work on the new monoplanes." that the British ordered in 1936-37. Only eight squadrons in England were ever equipped with them, some replaced the Bristol Bulldog.

But some squadrons had already re-equipped with Hurricanes by Sept of 1939. At which point they were being fosted off on the RN or overseas stations.

The Gladiator could easily have seen some improvement (like many other British planes) by fitting it with a 2 speed or variable pitch propeller. Given the British shortage of production capacity for modern propellers it was probably pretty far down on the list of priorities.

 

[tomo pauk]

The trouble is, even if it happened, you don't get anything really useable and you don't get a lot of good design experience, except perhaps what not to do
Supermarine 224
Fixed gear, thick wing, open cockpit of early Bristol 133
later
No flaps or flaps added later? Landing gear makes a P-35 look good. Why the fuselage is that fat for the engine it used or what had to go in it?

Sometimes, even knowing what not to do is a good thing

The Gladiator was never intended to be a "standard" fighter. It was another of the all too many "we need an interim plane NOW, to equip the new squadrons with while we work on the new monoplanes." that the British ordered in 1936-37. Only eight squadrons in England were ever equipped with them, some replaced the Bristol Bulldog.
But some squadrons had already re-equipped with Hurricanes by Sept of 1939. At which point they were being fosted off on the RN or overseas stations.

The Gladiator could easily have seen some improvement (like many other British planes) by fitting it with a 2 speed or variable pitch propeller. Given the British shortage of production capacity for modern propellers it was probably pretty far down on the list of priorities.

Hmm, yes, how about the Gauntlet monoplane then?

 

[swampyankee]

Vaguely back on topic -- how about a better air filtration system for the Merlin, at least as installed on the Spitfire and Hurricane?

 

[Shortround6]

Vaguely back on topic -- how about a better air filtration system for the Merlin, at least as installed on the Spitfire and Hurricane?

I think they finally got one.
The Updraft carb was probably a mistake in hindsight as any air intake on the bottom of the plane and 4-6 feet behind the propeller is going to catch all kinds of crud the prop blast/swirl kicks up, especially when the tail wheel comes up and the prop is only inches from the sod, dirt, sand, coral, etc, etc.

P-40s and Allison P-51s had the air intake on top and only inches behind the prop so their intake of self made grinding compound was much less, However formation take-offs needed care as your buddy's/wingman's plane could sure kick up enough crap to kill your engine.

The Vokes filter was probably overkill but few people had designed air filters for aircraft at that time.
The B-26 sure got some large air intakes when they sized them to fit filters.

 

[Kevin J]

I think they finally got one.
The Updraft carb was probably a mistake in hindsight as any air intake on the bottom of the plane and 4-6 feet behind the propeller is going to catch all kinds of crud the prop blast/swirl kicks up, especially when the tail wheel comes up and the prop is only inches from the sod, dirt, sand, coral, etc, etc.

P-40s and Allison P-51s had the air intake on top and only inches behind the prop so their intake of self made grinding compound was much less, However formation take-offs needed care as your buddy's/wingman's plane could sure kick up enough crap to kill your engine.

The Vokes filter was probably overkill but few people had designed air filters for aircraft at that time.
The B-26 sure got some large air intakes when they sized them to fit filters.

The Vokes filter also contained the extra oil tank required for ferry flights. That's why its so big and bulky.