Swappable P38 w/Plans - Twin engine goodness

by filken | September 2, 2013 | (48) Posted in Projects

So I just got into this hobby about a month ago and my wife has accurately labeled me as obsessed. I have built 5 FT planes and can't wait to build more. That leads me to the reason for this article. My father and I both built a spitfire from a speed-build kit and it was an amazing experience. The planes fly great and look amazing. If you haven't built a Spitfire, you should. 

The problem is that I am not easily satisfied and I started thinking about designing and making my own plane. I try to avoid things that contain the words "beginner" or "starter" so I usually jump in with both feet into something more advanced. I started by making a basic model in Sketchup that sort of looked like a P38, but it wasn't pretty, so I did some research and found some better techniques. To get the dimensions I took a 3 view of the actual plane and traced everything as scale as is possible with foam board. I believe that the dimensions should be fairly scale with the Spitfire so you could fly them together and it would look accurate. I did my best to make it using the build techniques and concepts used by FT on the other builds so if you are familiar with building their other planes you should be able to make this without too much of a learning curve. It is designed for 2 power pods, but it would not take a whole lot to install a permanent motor mount. So here it goes.

 

Specs

Wingspan: 54 1/2”

Dihedral: 5 Degrees

Length: 36”

Motors: 2x 1100kv 2208-17 Outrunners

Speed Controller: 2x 20A

Battery: 1x 2200MaH 3S 25c LiPO

Servos: 3x 9 gram

Props: 9x4.3 (I would recommend using a steeper pitch blade but these were the only pair I had available)

Aileron, Elevator, Differential thrust in place of mechanical rudder. 

 

My maiden flight went really well. The landing...not so much. I discovered that although it flies slow rather well, it does not glide all that well. After a rather impressive cartwheel following a stall I found that this plane can take a hit and keep on going. The wing tips got a little bent up, but nothing that a little packing tape wouldn't fix. I picked it up and chucked it back in the air and it flew just as well with mushed wingtips. If I keep up the power until just before I land, it goes much better. Make sure you are comfortable with 4 channel planes and using the rudder before lobbing this monster skyward. I wanted to keep the design as simple as possible so I didn't design it with a mechanical rudder. I decided instead to use differential thrust by mixing in 2 throttle channels with the rudder channel.  

I have included scale PDF plans so if you want to make some modifications you can do it without too much difficulty. If anyone knows how I can post the Sketchup files that would be great. When I try to upload them it just says "Bad Data". My guess is that file type is blocked. I also uploaded the 3D model and the 2D plans to the Sketchup Warehouse. http://sketchup.google.com/3dwarehouse/details?mid=f548f4e302169b4445f31985fc702c6e

To make the 2D plans I copied the surface from the 3D model and pasted them into a new drawing and flattened them out. That way I can make modifications without having to re-do a whole lot. The 3D model is to scale so you can take measurements and dimensions off of it if need be. It took 5 sheets of foam board, but that is because it is gihugimous. I haven't had a chance to mock up the removable nose/battery holder. I just got creative with some scraps of foam and poster board. I will post more pictures when I get a chance. I just updated the plans to include the plate that holds the skewers for the power pod

You will also need a hand full of servo wire extensions. The elevator servo needs to be about 50” long (I used a 36” and an 18”), and 4 more 18” extensions for the speed controllers and ailerons. You'll need a Y-Splitter for the aileron servos. I just stole the one I had for the Spitfire. I wanted to keep the weight down so I made an 18” Y-splitter for the power and the speed controllers share a battery, but I made the cockpit large enough to carry 2 batteries if you so desire.  

I tried and tried to come up with a way to make the wings removable, but since they are both attached to the elevator it's pretty much impossible without weakening the structure or making it too complicated. Feel free to play with the designs and let me know if you have any workable ideas. Here are some pictures of the final product. I will try to get some video of it in action in the next couple of days. 

 

 


 

 The video is a little jerky but I think it's pretty good considering it was taken by my 5 year old son on my cell phone. I love the theme music on the first flight. 

 Tell me what you think and if you decide to build one. More pictures coming soon. 

Thanks for reading.

 

P38_LeftWing_Plans.pdf

P38_RightWing_Plans.pdf

P38 Elevator/Rudder Plans

P38_Cockpit_Plans.pdf

P38_LeftNacelle_Plans.pdf

P38_RightNacelle_Plans.pdf

COMMENTS

flight monkey on September 5, 2013
That is Sooo cool! Is that ft Cruiser influence I see ? Cool. Im going to build a P-40 from the ft Slinger. (After the slinger is done, ofcourse). I like that you made it aerodynamic where it needs to be. Nice clean lines, Awsome Job! This deserves a follow up video, Maiden flight vid Please..... Nice to see its a Family hobby : )
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LALooper on September 8, 2013
Out of this world. The flosser control horns are just icing on the cake. I thought I was done building....glad all my motors are cheap, it won't cost much to match one of them for a twin.
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JasonEricAnderson on September 6, 2013
Great work! You've got a great cameraman there. Your work here has given me some ideas I want to use with my OV10 I'm working on.
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nathauff on September 6, 2013
beautiful i love it

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murraykyle22 on August 26, 2015
Every time I try to access his plans on sketchbook, I get an error message. Does anybody know where else to get them/ if he could update them?
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filken on October 13, 2015
The plans I uploaded are PDF files and can be viewed with Adobe Reader or equivalent PDF viewer. If you are interested in the Sketchup plans they are available in the Sketchup 3D Warehouse. Just search for P38 and look for the models posted by Kyle E. Here are the links as well. https://3dwarehouse.sketchup.com/model.html?id=50e793fe39e527b245f31985fc702c6e https://3dwarehouse.sketchup.com/model.html?id=f548f4e302169b4445f31985fc702c6e
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goeland86 on September 7, 2013
That looks really cool! Of course me being the tweaker that I am... Would you mind if I took a stab at making the nose a bit more pointy? I remember the P-38 I saw at an airshow having a rather pointy nose. And I think it can be done using FT build techniques, just need to combine them.
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Nathan_116 on September 16, 2013
If you ever get it to look more scale post the "updated" plans here also don't for get the scale bumps on the side of the nacelles and the canopy. As much as I love these designs a scale clear canopy would make it that much better
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filken on September 8, 2013
Have at it. I'm always looking for ways to improve the design. Just so you know, I did it that way though to make the nose simple to remove. I actually made a new nose cover with a battery tray so I could get my CG right. I have a 2200 all the way forward and it does the trick but just barely. Let me know how it goes. I look forward to your results.
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mcepic on October 4, 2013
wow you deserve a showtout nice job i want to build one now i look forward to see you make more planes
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Jaxx on September 10, 2013
Is that the FT Racer in your profile picture? If so, could we get a close-up picture of the canopy? Thanks.
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filken on September 10, 2013
Actually it's my new P51 Mustang design I made this weekend. I just finished the article on it this evening so it should be out as soon as it is approved. The plans and 3D model are in the Sketchup Warehouse if you want to look it up.
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Jaxx on September 11, 2013
I will definitely be building the Mustang! Will you be posting PDF planes with the article?
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filken on September 11, 2013
I like your enthusiasm. Fear not! The article has plans, pictures, and build instructions. I just maidened it today and it is a rocket. It's my new favorite plane! I'll post the video in the article as well.
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Jaxx on September 12, 2013
That's awesome. I love war birds, and now that I've built the Spitfire, I'm hooked. Thanks again for the work you have put into these designs. I hope it doesn't take me too long to become proficient with Sketchup. I would like to build a swappable Piper Cub. I always liked that plane.
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Orcoz on September 8, 2013
5 out of 5 for your cameraman/commentator!
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Flying Penguin RC on September 5, 2013
Nice job, I might have to build one.

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Crashpilot1000 on September 6, 2013
Well your 5yo son is better on the camera than "Barry" on the rc model reviews channel.
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Jaxx on September 10, 2013
Are you telling me you only have two weeks of experience with Sketchup? That makes this project even more impressive!
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filken on September 5, 2013
I just updated the plans to include the power pod mount plates and uploaded the 2D and 3D plans to the Sketchup Warehouse.
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Nathan_116 on September 16, 2013
Where is the sketchup warehouse???? Been looking but can't find it.
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filken on September 18, 2013
http://www.sketchup.com/products/3D-warehouse
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RotateB4TheEnd on September 6, 2013
A+ for the cameraman! He is more stable than some adult-shot videos!
Also a great plane. May have to try this one day:)
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GunHog on September 5, 2013
Nom nom nom nom da nom nom nom. Hahahaha! THAT is a GREAT family video! Great job.
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JustinTime on September 6, 2013
You could have made the outer wing panels removable if you wanted to make the wing removable. Would have left the booms and the stab intact with the fuse.
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Zatoichi on September 5, 2013
Man that thing is way cool.Filken awesome as a matter of fact!=D
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Christian Jeppesen on September 5, 2013
Nice work really. Now yet another great Swappeble is available for all foam-board scratch builders :D.
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GB-air on September 5, 2013
Looks great! Did you use flossers for the control horns? I think I might adapt that technique. Great idea!
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filken on September 5, 2013
Yes, those are dollar store flossers. I can't take credit for the idea though. Not sure where I saw it but I was searching for a replacement for the popsicle stick ones I have made in the past and ran across this idea on the interwebs. They work great and you get 35 for $1.
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Aquanot on September 6, 2013
make an extra post about this flossers as control horns. great technics and trixs have to be shared! great idea!
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Aquanot on September 6, 2013
very nice! seems for me that a long working winter is comming and wont leave my mancave to often :-)
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Jaxx on September 9, 2013
Great work! How long have you been using Sketchup, and what version are you using? Thanks.
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filken on September 10, 2013
I started using Sketchup 2013 about 2 weeks ago. I looked at a bunch of CAD software, but it was by far the easiest to use once you get used to the quirks. The think I like is that you can take a 2D wing plan, for example, and fold it over, make it 3D and make sure everything lines up before you print out the plans. You can also take pictures of any parts that you make that weren't part of the original plans and as long as you know the dimensions you can scale the image and trace over the lines. The important thing to remember is to make sure all your lines on the 2D version are co-planer. Otherwise you'll hate it and nothing will work right.
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Nathan_116 on September 9, 2013
Beautiful, that takes one more plane off my to design list, the only thing I don't like is the the lack of landing gear/retracts. :( :)
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filken on September 10, 2013
It actually belly lands quite nicely, but if you design some good landing gear, share because that would be awesome.
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Jaxx on September 11, 2013
You did all this with two weeks of Sketchup experience? You have just motivated me to dive head-first into learning Sketchup.
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Flynn on September 5, 2013
Your son is too funny! Great vid man. My father in law thinks its great, mainly cause he saw the real thing in WWII.
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Okie on September 7, 2013
love it really great build and the cameraman is so helpful just wondering how many sheets of foam board did you use to build it
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filken on September 8, 2013
It took 5 sheets, including 1 power pod.
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FeWolf on September 25, 2013
Have some trouble with the wings can you do a build or time lapse video?!
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filken on September 26, 2013
Unfortunately I didn't do a good job of taking enough pictures of the build steps but maybe it will help if I explain it in more detail. They way I did the wings is very similar to what Josh does in the build video for the Versa, except I sand them down at a 5 degree angle to give the wings dihedral. I put the wings bottom up on the table, pushed them together and put a piece of packing tape on the bottom just like the Versa. Then I slid both nacelles in place, lined them up and pressed the bottoms flat against a table. That gave the right wing angle. It should not take a lot of force to hold the nacelles flat. If it does, you have more sanding to do. Then it's just a matter of slathering on some hot glue and pressing everything together. I also put a strip of tape on the top of the wing for extra strength. Make sure you don't glue the nacelles on at this point though or you won't be able to put the cockpit on. Hope this helps. Let me know if you need more assistance.
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neilborj on November 12, 2013
Thanks for sharing the plans. I used it to build one. It flies great. The build was heavily modified but without your well made plans, My build would not have been possible.Again thank you. Here is the video.
http://www.youtube.com/watch?v=RIgh5fcuG0E
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filken on November 13, 2013
That's awesome! Great job on the mods. I'm glad you found the plans useful. Do you have any pictures of what you did differently?
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neilborj on November 17, 2013
I dont have pictures but maybe later I can take a few to show the mods. The cockpit is made of 3 layers of 1 inch thick pink foam sanded to get the right shape, I carved out the battery compartment on top of the nose. Installed a steerable nose gear. Used a plastic spray bottle cut to shape like a canopy. Added a pilot . The nacelles are made of two- 1 inch pink foam sanded and shaped. I sandwich them with a single layer of DT foam using your patterns. At the bottom I carved out a space for the esc and wires. Installed a fixed landing gear for each. The wing is made exactly per your plans and design ( so nice and easy to follow). I added flaps -two sections per wing like the real one but uninstalled them when I realized they are not necessary after its maiden flight.I also added engine air intake and exhausts for scale appearance on both engine nacelles by carving out pink foam. I fiberglassed the whole plane using water-based minwax and fiberglass cloth, then air brushed it with cheap (apple barrel) acrylic paint. Last I applied a single coat of the same minwax to protect and seal the paint. I was thinking of doing a differential thrust but after a smooth maiden flight I decided not to. All dimensions were based entirely on the plans. Again thank you for sharing your time and talent.
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Yogenh on March 29, 2014
I really would love to see the mods you did and how to do them. I really would love to know more about the landing gear!!!!
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Yogenh on March 29, 2014
I could not see the video came up unavailable. Would have loved to see it.
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Yogenh on November 7, 2013
I love it you did great work with it. I have to make me one now!!!
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neilborj on November 17, 2013
Correction, I initially used the oil based Minwax only- on the wing and the nacelle sides (one coat) since they are the only parts that I use DT foam . Thanks.
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hensonnlee on December 12, 2013
I really love your plans for the P-38 but I have a few questions. 1) When you installed the motors how did you mount the motor pods. 2) Do you have a drawing of the front nose covering that you used.
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filken on February 9, 2014
Sorry for the late reply. I used standard power pods and mounted them to the plate that goes just below the wing. They end up being at an angle because they are mounted flush to the plate at the same angle as the wing dihedral. I used the same barbecue skewer mount setup that FliteTest uses on all their swappables. Unfortunately I do not have a drawing of the front nose covering. I just made something out of scraps and never got around to measuring it. It's not too difficult though. I just made the poster board way too big, built the supporting foam pieces, and then put everything in place and drew around the nose. That gave me some cut lines to go with. I hope that helps.
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smashed2bits on November 14, 2014
awesome job! i was going to try to take this project on but I don't think I could top this. I can't believe how doscile it looks in the air and on takeoff. I am definitly building one of these. but what motor/esc are you using?
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smashed2bits on November 14, 2014
i figured out the motor/esc combo, but are they counter rotating?

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filken on November 14, 2014
I did have them counter-rotating so I could use differential thrust instead of having to make a dual rudder setup. Flitetest has a great video on how to set that up.
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thai.hong.733 on November 2, 2014
may i ask you a question is it possible to build those planes plan using aluminum cans or soft drinks cans. if can please tell me about. cause i am think of making planes out of soft drink cans. i like your vids they are the best examples for beginners to follow and build.
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filken on November 14, 2014
Thanks for your comment. Honestly, I have only ever built planes out of foam, so I don't have any experience with aluminum. I know some people have used aluminum foil over their frames for aesthetics, but that's about it.
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Hannes on November 5, 2014
Nice, I think I will build it rather than the FT cruiser, lol:)
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johnnyjiujitsu on October 13, 2015
One thing I was curious about is the trailing edge of the bottom part of the wing on the plans. Is that detached or beveled or what is that?
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filken on October 13, 2015
That's a spacer that is sandwiched between where the bottom and top sections of the wing meet at the back. It is a separate part.
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jordy123 on April 26, 2016
make the fuse and booms curved
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jem5805 on May 3, 2016
just built this out of the new water proof dtfb. Does anyone know the CG
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filken on July 31, 2017
Sorry for the late reply. Jpot1 just asked the same question so you can read my reply a couple posts below this one.
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John Frenzel on January 8, 2017
how much must I enlarge the plans to be usable?
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Sir Fly on June 17, 2017
Wow this plane looks amazing! What size powerpack did use?
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filken on July 28, 2017
Thanks! I just used some motors and speed controllers I had laying around, but Power Pack C would do the job nicely. I'd recommend getting a couple more servo extensions just to be safe because the elevator servo has to go quite a long way.
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Jpot1 on July 28, 2017
Is the CG on the spar?
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filken on July 31, 2017
I would suggest starting just a bit (a finger width at most) forward of the spar closest to the cockpit. With the dihedral you may find it easier to feel the balance if you put the plane upside down. The elevator is quite large so it can handle being nose heavy much better than it can handle being tail heavy so erring on the side of nose heavy is best. Sorry I can't be more specific. I haven't flown this plane in several years and I can't remember exactly where it is, but that should get you close enough to fly.
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Allen C.Y. Wang on January 14, 2018
may i ask what size of the papers should i use when printing the drawing out by 1:1?
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Swappable P38 w/Plans - Twin engine goodness