WesWorld

A possible new aircraft for the USAAC, the Curtiss XP-41 is intended to be a lighter weight aircraft than the XP-40, based on the lessons learned from examining the Bf-109. As designed, the XP-41 is powered by a turbosupercharged Continental I-1430-1 engine, armed with 4 0.50" HMGs in the wings, and (based on reports from South America) fitted with a 0.50" sheet of armor plate behind the pilot.

[Note: the WW I-1430-1 has the lower output of the historical O-1430-1, but the inverted-V layout of the I-1430. Later models of the I-1430 series will, if development continues, show the usual increase in output.]


Aircraft Type or Name:

Curtiss XP-41

General Type:
Airplane = 1
Airship = 2
Orbiter = 3
1

Year of First Flight: 1939

Description

Carrier or Rough Field
Monoplane with Struts
Conventional Fuselage

A fighter for the USAAC. Armed with 4 0.50" caliber machineguns in the wings, and fitted with .5" cockpit armor. Capable of carrying a 250 pound bomb below the fuselage. [Note: the WW I-1430-1 is a turbosupercharged engine with output based on the O-1430-1, but with the inverted-V layout of the I-1430.]





Characteristics:

Weight (maximum) 7,000 lbs
Weight (empty) 5,846 lbs

Length 31.5 ft
Wingspan 38 ft
Wing Area 237 sq ft
Sweep 1 degrees

Engines 1
Continental I-1430-1
Piston

1,148 hp
at 25,000 ft


Crew 1


Typical cost $0.040 million in 1939
Total number procured 2000


Performance:

Top Speed 358 kts = 412 mph
at 25,000 ft
Mach N/A

Operational Ceiling 42,500 ft

Range 450 nm = 518 miles
with 447 lbs payload
462 lbs released at halfway point

Climb 2,351 fpm

Cruise 250 kts = 288 mph
at 25,000 ft

Corner Speed 231 KIAS =
346 kts at 25,000 ft
Mach N/A
Turning Rate 20.2 deg/sec
Radius 3,315 ft



Internal Data:

Intake / Fan Diameter 10 ft

Bypass Ratio 97

Engine Weight 1300 lbs
Overall Efficiency 22.5 percent

Structural Factor 0.99

Number of Wings 1.01
Number of Fuselages 1

Limiting Airspeed 500 kts
Wing Ultimate g Load 10.00 g
Wing Taper 0.2
Wing Thickness at Root 1.2 ft

Tail / Canard Factor 0.4

Number of Nacelles 0
Length 6 ft
Diameter 4.5 ft
Fullness 0.5

Fuselage Diameter 3 ft
Fuselage Fullness 0.35

Pressurized Volume 0 percent
Cargo Decks 1

Cleanness 80 percent
Unstreamlined section 1.2 sq ft

User equipment 1,120 lbs

A couple of notes :
Externally braced probably does not accord with max cleanness. while the cleaness req. is entirely Date based.

Fuselage diameter of 3 feet is likely insufficient to small for the cockpit space- based on the size of engine-independent central nacelles. I'm also curious if the engine fits in that.

Yeah, the "strut" thing got me, I've cleaned it up, hadn't realized what caused it until I noticed that.

The engine fits, no problem there, if you look at the data RA provided the I-1430-1 had a diameter of 32.25".

The fuselage is small and tight, no question, but not out of the realm of the possible (the Ki-62/-100 had a fuselage that was only 33" in diameter).

Might want to add some length or width for the turbo and ducting. The engine length stated just includes the engine block itself with the integral supercharger at the rear. With the turbocharger installation theres another 4ft of ducting, the turbo itself, and most likely an intercooler.

With regards to power, scaling off the turbocharged V-1710F series in the P-38, the power looks to be around 1010hp up to 25,000ft. The 1150hp figure for the O-1430 is on 100/130 oct fuel rather than 87 oct.


Any idea what it'll look like?

Length doesn't appear to be a problem, considering the XP-40 which was turbo-equipped and wasn't any longer than the later models (and about the same size as the hypothetical XP-41)

The US isn't expecting to use any 87 octane fuel in combat aircraft, 100 octane fuel was historically delivered for testing and development in 1935 and that's clearly the future. If the XP-40 or XP-41 should have to run on 87 or 92 octane, adjustments will have to be made.

As to looks, I'm expecting it would look kind of like a cross between the original XP-40 (with the top-mounted inlet for the turbo) http://i145.photobucket.com/albums/r202/…40/XP-40001.jpg and the early P-40 http://i145.photobucket.com/albums/r202/…4039-160001.jpg with the smallish radiator under the nose. Of course there are no nose guns.

This is a version of the P-41 design without the GE turbocharger. It's top speed ia a little faster than that of the historical Bf-109E/WW Bf-109B, but the climb rate is definitely inferior to the German aircraft.


Curtiss YP-41

General Type:
Airplane = 1
Airship = 2
Orbiter = 3
1

Year of First Flight: 1940

Description

Carrier or Rough Field
Monoplane
Conventional Fuselage

A fighter for the USAAC. Armed with 4 0.50" caliber machineguns in the wings, and fitted with .5" cockpit armor. Capable of carrying a 250 pound bomb below the fuselage. [Note: the WW I-1430-5 is a supercharged engine with output based on the O-1430-1, but with the inverted-V layout of the I-1430.]





Characteristics:

Weight (maximum) 7,000 lbs
Weight (empty) 5,987 lbs

Length 31.5 ft
Wingspan 38 ft
Wing Area 237 sq ft
Sweep 1 degrees

Engines 1
Continental I-1430-5
Piston

1,148 hp
at 15,000 ft


Crew 1


Typical cost $0.043 million in 1940
Total number procured 2000


Performance:

Top Speed 324 kts = 373 mph
at 15,000 ft
Mach N/A

Operational Ceiling 35,500 ft

Range 400 nm = 461 miles
with 302 lbs payload
313 lbs released at halfway point

Climb 2,355 fpm

Cruise 250 kts = 288 mph
at 15,000 ft

Corner Speed 232 KIAS =
292 kts at 15,000 ft
Mach N/A
Turning Rate 24.1 deg/sec
Radius 2,351 ft



Internal Data:

Intake / Fan Diameter 10 ft

Bypass Ratio 97

Engine Weight 1300 lbs
Overall Efficiency 22.5 percent

Structural Factor 0.99

Number of Wings 1
Number of Fuselages 1

Limiting Airspeed 500 kts
Wing Ultimate g Load 10.00 g
Wing Taper 0.2
Wing Thickness at Root 1.2 ft

Tail / Canard Factor 0.4

Number of Nacelles 0
Length 6 ft
Diameter 4.5 ft
Fullness 0.5

Fuselage Diameter 3 ft
Fuselage Fullness 0.35

Pressurized Volume 0 percent
Cargo Decks 1

Cleanness 83 percent
Unstreamlined section 1.2 sq ft

User equipment 1,120 lbs

Why does your fighter have a cargo deck?

Quoted

The engine fits, no problem there, if you look at the data RA provided the I-1430-1 had a diameter of 32.25".

The fuselage is small and tight, no question, but not out of the realm of the possible (the Ki-62/-100 had a fuselage that was only 33" in diameter).

I've been pretty busy, haven't been keeping up and didn't register that engine post. That's a fair bit smaller than the next contestant (of decent size) I have an overall diameter for.

On fuselage diameter, I realize it may be a little silly to quibble over 5 inches, but...

The Ki-62/-100 reference confuses me (The what ?). Not the least because I'm not very 'up' on Japanese planes, particularly land based

Googling the Ki-62 gets a couple slightly different answers, but it doesn't sound like it ever made it past the prototype stage. So there is no assuredness that the cockpit was adequately sized for combat ops, didn't cause undue pilot fatigue, etc.

Edit : I don't want to kick off a small pilot fad, but my general impression from WW II pics is that the average Japanese serviceman was smaller and more lightly built than American servicemen. A minimum size cockpit for one may not be adequate for the other.

The Ki-100 was a Ki-61 with the nose re-arranged to fit a radial. Scaling off a pic, if it's 29ft. long, then the fuselage appears to closer to 4 feet than 3.

So, I still feel something like the the cross-section of the P-38 central nacelle (~3.4ft) is a more prudent source of a minimum size.

The US should license-build the Spitfire. Because Spitfires are cool.

Heh, the US is unlikely to license build the Spit, since it did not do so historically.


Blasted cargo deck left over from a previous plane.... maybe that's why I can't get the weight down?

Should be the Ki-61/100, the Ki-61 had a fuselage width of 33", then when the Ki-100 was created as an adaptation of an airframe to an engine for which it was not designed, that 33" fuselage was mated with an engine of rather larger diameter.

I'll remeasure when I have time, but I was measuring the Ki-100 cross section right at the cockpit- well behind the engine and using length for scale.

Thought you'd appreciate the Cargo deck catch

Have to be careful with the Ki-61/100 fuselage, it's taller than it is wide. Another source I was just looking at says the Ki-61 fuselage was 30" wide, which might be a LITTLE narrower than it actually was but probably very close. The DB-605 engine was 760mm wide, which translates into just about that, and the DB-601 copy used in the Ki-61 wouldn't have been wider than the slightly larger DB-605.

You are quite correct that for fuselages you can't rely on just one view.

All I do is find a side & top view scale drawing or plan of the plane on the web, use the length or wingspan to establish the scale of the drawing, and then take hieght & width measurements of the fuselage (in this case, chord in other cases, etc)- which then get averaged for the overall diameter. I find a fair number of fuselages are ovoid.

However, I should be working

ok, found a nice site with some good drawings of the Ki-61.
Once printed out, I used my engineers scale to measure wings, fuselage height, width.
Wings measured 540 units (1/60in), vs. a span of 39ft, 4in.
That gives 0.87 inches per unit of measure.

Fuselage width was 37 unit, or 32.2inches.
Fuselage height was 57 units, or 49.61 inches, trying to exclude canopy and cooler.

That gives an average diameter of 40.91 inches or 3.41 feet- right about what I consider the minimum.