31 January 2023: Added a size comparison of the XFL-1 and P-39 empennages.
The Bell XFL-1 Airabonita was a one-off prototype based on Bell's P-39 that competed with the Vought XF4U-1 and the Grumman XF5F-1 following the U.S. Navy's 1938 carrier-based fighter competition.
It looks like it would be a colorful and straightforward conversion of the P-39, kits of which are available in every popular scale from 1/144 to 1/32. In fact, several have been done and documented in articles in modeling magazines. However, most—if not all—fall short of representing the actual XFL-1 configuration. Unfortunately, most of the structure, particularly the canopy, was different in detail from the P-39. Not even the 1/72 XFL-1 kits that are available are accurate, since they have the P-39 wing planform, which was somewhat different in taper and span.
For example, this is what it takes to convert a P-39 wing to an XFL-1 wing:
The empennage (both initial and final) is also very different from the P-39's (the final horizontal stabilizer is about the same size and shape but the elevator itself has significantly more chord).
Another, more notable difference was the canopy and door, since over-the-nose visibility was critical for a carrier-based airplane.
All this and more is contained in my XFL-1 monograph, available from Steve Ginter:
All this and more is contained in my XFL-1 monograph, available from Steve Ginter:
In addition to most of the photographs extant of the XFL-1, there are illustrations of the configuration changes during development like the empennage. Since the Navy specifically included the XFL-1 in the competition to evaluate the performance benefit of the new 1,000-hp Allison liquid-cooled engine, it includes a summary of the history of aero-engine development, comparing and contrasting the benefits and shortcomings of the liquid-cooled versus air-cooled engine. It also places the XFL-1 in the context of the Navy's rapid transition to monoplanes and new requirements like armor and self-sealing fuel tanks.
Even if you don't need a model of an XFL-1, the monograph provides interesting background on aero engine and Navy airplane development between the World Wars.
The XFL may have lost to the F4U, but it shows that Bell could make a Cobra with a tailwheel for a short take-0ff, and carry fuel for a longer combat radius. Just these 2 flaws made the P-39 a logistical headache. The larger wing addressed the Cobra's stall-turn handling, and spin was damped a bit by the taller tail. If only it kept the turbo of the XP-39! It was a Navy fighter. If it was free of the Army's rationing of turbos on their own fighters except P-38s, the XFL should have developed the B5 turbo with rare tungsten for reliability. So, without guns it had a top speed in 1940 of only 336 mph at 10,000' and 307 mph at s.l. Climb to 20,000' took 9.2 minutes - about the same as the faster P-39D with guns. At least the XFL had a supercharger like the P-39s. The P-400 Cobra didn't. So it took 15 minutes to climb 20,000'. The Cobra could have been better due to the Bell XFL fighter.
ReplyDeleteHi,
ReplyDeleteI have your XFL-1 monograph and I can say its extremely interesting throughout.
I'm building RS Models injection moulded 1/72 Bell XFL-1 kit soon, and apart from the problems with the wing plan, I wondered if you were aware of any other issues with the kit?
I'm probably going to build the model to depict the aircraft in its final flight test configuration, which I think means a larger fin/rudder, wide span tailplanes, different radiator housings and carb inlet, and fewer cowling louvres. I was wondering if you know of any other necessary changes?
The larger fin/rudder I would probably scratchbuild, but I wondered of P-39 tailplanes and carb intake could be used.
I'd be very grateful for any thoughts or suggestions you may have.
Many thanks and best regards,
Mark
Mark - I don't have what I consider to be accurate P-39 drawings at the moment but comparing the XFL-1 empennage to the P-39's using the best one I found on line, the P-39's is not nearly close enough to be of use, particularly considering it is smaller. The P-39 carburetor intake, on the other hand, looks appropriate. I regret to say that I didn't do a close comparison of the available 1/72 XFL kits to the drawings other than the wing...
ReplyDeleteTommy
Hi Tommy,
Deletemany thanks for your reply - that's really helpful as I know now that scratch-built tailplanes will be needed. Good news about the cab intake, though, and it looks like Eduard do suitable six-stub exhausts in their Brassin range.
Discussing this project on the Britmodeller forum, another member has suggested that any panel lines would be faint if not invisible - phots in your book seem to bear this out - as it was a development aircraft and Bell wanted it to perform as well as possible so it was particularly well finished. Would you agree with that?
I've just started cutting the wings.....scary stuff!
Many thanks once again,
Mark
Depiction of panel lines not visible in photos taken from a distance of more than 50 feet or so is an artistic choice in my opinion. That said, there are some on the XFL-1 fuselage that meet that criteria like the access to guns/ammunition and the engine. Good luck with your conversion. Please share pictures of it.
DeleteMany thanks for your reply - that's good to know!
DeleteI was thinking of depicting panels lines with the aid of slight variations on the aluminium lacquer and by using lightly-drawn pencil lines, a technique I've seen used to good effect. Panel lines like those you mention definitely need to be a bit more prominent!
Happy to share pics when its done! Its entered as part of a current Group Build on the Britmodeller forum, but progress will be slow and the more I learn the more I want to get it as accurate as possible, so it may be a while before I finish!
Many thanks once again and best regards,
Mark