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Swappable P-40 Warhawk / Kittyhawk MkIA

#1
After seeing the Flitetest Swappable Spitfire, and the Swappable Bf 109E and P-51D by Ultramicrobe, I wondered whether you could make a Swappable P-40. Having some foam board on hand, I thought I would give it a try.

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The Curtiss P-40 Warhawk (Tomahawk and Kittyhawk in RAF nomenclature) was the front line fighter for the US Army Air Force at the beginning of WWII. Although some considered the P-40 obsolete at the beginning of the war, in the right hands she proved to a formidable fighter and served in most theaters of combat with most Allied air forces throughout the war. The Warhawk / Tomahawk / Kittyhawk gained fame with the RAF Desert Air Force in North Africa (No. 112 Squadron being the first to put the shark mouth on the P-40.) and the American Volunteer Group “Flying Tigers” in the China-Burma-India Theater (Who made the shark mouth famous.). By war’s end, she would be the third most-produced American fighter.

During the filming of the 2001 movie Pearl Harbor, the P-40 used in the film would bank over my house, her Allison engine roaring, as she headed back to Pearl Harbor – an absolutely beautiful sight.

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Following Ultramicrobe’s lead and suggestions, I downloaded the FT Swappable Spitfire plans, planning to use as much of the plans as possible, especially where two parts meet. I then downloaded off the internet diagrams of the P-40E Warhawk and scaled them up to the Spitfire plans for the necessary alterations.

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The fuselage stayed almost unchanged. However, the one distinctive profile feature of the Warhawk is the large coolant radiator under her chin. This was traced onto the Flitetest fuselage plans. Other changes included changing the profiles of the horizontal and vertical stabilizers, straightening out the Spitfire’s elliptical wings to match those of the Warhawk and adding in P-40 wingtips, all of which were drawn onto the Spitfire plans.

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The build was otherwise straightforward following the Flitetest plans and video. Parts joined just like the Spitfire. The only changes to the build were adding signature P-40 details: A bottom piece under the chin to emphasize the chin radiator (secured by hot glue at the rear and with magnets in the front to open to allow battery access); adding the Allison engine carburetor air scoop on the nose; adding the spine down the center of the fuselage belly; and adding the two landing gear door bulges under the wings. The electronics are the Flitetest recommended “The Beef” set up from Hobbyking.

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After applying Minwax, I painted her rattle can olive on the top and neutral gray on the underside to match the USAAF color scheme for late 1941 through 1942. The P-40E was the version used in this timeframe to replace the P-40B’s and P-40C’s lost in the attacks on Pearl Harbor and the Philippines. Decals were made using PowerPoint and OfficeMax adhesive 8 ½ X 11 label paper, protected with an overspray of rattle can clear matte finish, and finished off with a light buffing with superfine steel wool.

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I decided to do an open cockpit and not add the distinctive shark mouth, just to do something a little different.

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As with the FT Spitfire, the CG is over the wing spar. Unlike the FT Spitfire, mine turned out to be tail heavy with a Hobbyking 1300 mAh 3S battery up front, probably because I had to use the heavier Office Depot foam board since Dollar Tree foam board is not available in Hawaii. Rather than add dead weight, I have opted to go with the larger 2200 mAh 3S, which is on order, so I cannot give you a flight report at this time.

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If anyone else builds a Swappable Warhawk, I would love to see your work. Big thanks are owed to David Windestål for the original design and Ultramicrobe for the Bf 109E and P-51D alteration suggestions, tips and inspiration.

Keep’em flying!
 

Attachments

#5
This is a fantastic job! My father in law was in the Marines in the South Pacific during the war. We were just talking about the Flying Tigers and he told me that's the next one I have to make. Great work 808!
 
#7
808, Great Job!! the plane looks fantastic. Please keep us informed on your maiden flight, and how it goes, I used a similar design process for a J3 Cub design based on the "swappable" concept and had a great time doing it! I don't see any reason why almost any of our favorite planes couldn't be built in this way. (some may fly better than others).
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Edwin

Junior Member
#10
@ Newzee - No I used the 11 x 5.5 and it gave me à good power with the 390 Watt motor, so I will not change it.
 
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#12
It seems that this Spitfire plans are converted by everyone, and with a nice result :D

nice details, thats how i like them :applause:

Edwin

http://forum.flitetest.com/showthread.php?5796-just-%E0-photo-of-the-first-plane-i-have-Build
Everyone -

Thanks for the compliments. I enjoyed building her.

One question, with the NTM 28-26A motor and a 3S battery, what prop sizes are you using. I see Edwin is using an 11 X 5.5 on a 390W motor. Are you folks with the NTM using an 8 X 4, 8 X 6, 9 X 4.5, etc. I would be interested in hearing what you are using and how it is working.
 
#13
808,
What did you use to make the canopy?
Jaxx -

I used .015 inch thick "Polyethylene Terehthalate Coplymer (PETG)" plastic sheet I got at the local hobby shop. I think any thin, clear plastic sheet that is fairly flexible should do.

For the front windshield, I used Microprobe's canopy diagram from his Messerschmidt Bf109 Swappable for the front curve to match the fuselage curve. One difference is I used one piece for the front windscreen and folded the side windshield pieces vs. cutting them. I used some of the extra poster board as a template to get the sizes and angles, with a lot of trial and error until it looked right. Once the template was right, I traced it onto the plastic sheeting, cut it out, and folded where required using a ruler edge as a straight edge.

On the top canopy, it is the same plastic sheeting. I rolled the top and let it sit overnight with a rubber band around it to try to get a little bend in the sheet before attaching it onto the fuselage. Same with the rear view windows.

The canopy frames are just black duck tape cut into very thin strips. The rear window frames were made using PowerPoint, printed onto the self adhesive label sheets used for the other decals. The rear window frames were cut out and stuck onto matching plastic sheets.

Once all the frames were applied, and after many dry run double checks, I hot glued the canopy pieces to the fuselage. I was not sure the hot glue would hold them, but it did a great job. Just use a little since it spreads and keep pressure on it until it cools.

Hope this helped.
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#15
Everyone -

Thanks for the compliments. I enjoyed building her.

One question, with the NTM 28-26A motor and a 3S battery, what prop sizes are you using. I see Edwin is using an 11 X 5.5 on a 390W motor. Are you folks with the NTM using an 8 X 4, 8 X 6, 9 X 4.5, etc. I would be interested in hearing what you are using and how it is working.
I'm throwing a 9x6 on my V-tail without much trouble, but it rarely goes above 1/2 throttle. I've bench tested a 10x4.7 (should be comparable draw to the 9x6) -- it get's pretty warm at WOT, but really pulls hard. I'm thinking a 9x4ish prop will give you plenty of pull and stay nice and cool -- top speed for a 4.5" pitch for that power system would be about 57mph.
 
#16
Originally Posted by 808aerosquadron
Everyone -

"Thanks for the compliments. I enjoyed building her.

One question, with the NTM 28-26A motor and a 3S battery, what prop sizes are you using. I see Edwin is using an 11 X 5.5 on a 390W motor. Are you folks with the NTM using an 8 X 4, 8 X 6, 9 X 4.5, etc. I would be interested in hearing what you are using and how it is working."


I use a NTM 28 26 1200kv with a 9X6 APC prop on my Spitfire and it flys great, no heat on my 25A ESC or 1300maH lipo's