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56" Foamboard P-38 Lightning

Horseman3381

Well-known member
#1
This is my design for a foamboard P-38. There are other P-38 plans people have posted, but one of the things I enjoy the most about this hobby is designing and building planes (almost more they flying them), so I decided to design my own. For this plane I wanted something that was comparable in size to the FT Sea Duck, and could be built in approximately the same amount of time. It didn’t need to be terribly detailed, but I wanted it to look good enough that people instantly knew what it was.

P38-01.jpg



History:

This plane is version #2 of my P-38 design. My original design was more squared off, did not have the “radiators” on the sides of the nacelles, and was unnecessarily complicated to build. With what I have learned over the past year I was able to fancy up the design while cutting the build time and complexity. I brought this to Flite Fest 2018 where several people asked for the plans, and you can find them below.

You may notice the nose is a bit smushed, and the right wingtip is bent. The nose is from a taxi test of the plane before I added a servo to steer the nose wheel. I originally planned to control it on the ground with differential thrust, however if you need to turn to avoid something quickly, applying more power doesn’t work great. As for the wingtip, I wasn’t paying attention and walked into a door while carrying the plane.


Specifications:
  • Wingspan – 56”
  • Fuselage Length – 40 1/2”
  • Motor – (2) Emaxx GT2215/09 (FT C-Pack)
  • ESC – 30A
  • Prop – 8x6 3-blade or 10.5x4.5 2-blade (If you can find 9x4 or 5 3-blade let me know)
  • Battery – 3s 2200mah (I use 2, but it will fly and balance with 1)
  • Servos: (4) 9g
  • 6 sheets of foamboard


Preliminary Design:

When I started on this project I knew I wanted to use FT C-Pack motors. I used the FT Sea Duck plans as a start since it has twin booms and runs off twin C-pack motors. I brought the plans for the Sea Duck into AutoCAD and using the drawing below started to make modifications to make it look more like a P-38. This included tapering the wings and adding dihedral. The nacelles are stretched forward of the wing more, made taller and radiators added. The tail modifications are minor, simply reshaped vertical and horizontal stabilizers. The fuselage is drastically different and I started from scratch on that.

P38-02.jpg


The plane has ailerons, elevator and differential thrust. The rudder is used for the nose wheel only as I did not design actual rudders into the plane. I decided to keep things simple and use fixed landing gear with no flaps, however it would be easy to add them (maybe in version 3).

As I said, this is my version #2. Version #1 I had a fake “Grill” built into the nacelles below the motor, and did not include radiators on the back of the nacelles. The problem with this is that the large flat surface below the motor gave the same effect as flaps when throttling up and the plane would climb drastically. To address this, in version 2 I left the area below the motor open, and cut vent holes in the side of the nacelles under the radiators for air to escape. When initially test flying the plane with a 2-blade 10.5” prop this eliminated the climbing issue. However, when I put the 3-blade 8” prop on the climbing issue returned. I hope to find a 9” 3-blade prop for the plane that may help the issue.

P38-03.jpg


P38-04.jpg


When designing the fuselage I went through a few different designs of the nose trying to build it more geometrically and give a more overall roundedness appearance to it. However none of them looked great, so in the end I decided to go with a rounded nose and tapered sides which I think turned out pretty good.

P-38-05.jpg


After I had the plane together and a few test flights in something seemed missing. It finally dawned on me, spinners. I don’t use them on most of my planes, but I purchased 2” spinners hoping it would bring the plane together, and in my opinion they really did.

P38-06.jpg

(Note: The plans have been fixed so the nacelles should be square with the fuselage)


Landing Gear:

The main landing gear is 2 1/2” wheels I bought from a local hobby shop. They are anchored into the wing with the wire bent into a C shape for inside the wing with a matching pattern cut into a piec of foamboard to match. Then there is one more piece on top of that to hold it into place.

P38-07.jpg

Note: This image is from a previous writeup, in this plane the wheel axel is rotated 90 degrees

The nose gear uses a 2” wheel with a question mark bend. There are pieces of paint stick mounted inside the nose to reinforce where the landing gear mounts to the fuselage. A wheel collar on the outside of the plane (recessed in the foam) and a steering arm inside keep the gear in place. The arm is connected to the steering servo that is mounted to the side of the fuselage.

P38-08.jpg


P38-09.jpg



Paint:

After a few successful test flights it came time to paint. I based the paint scheme on the plane Happy Jacks’s Go Buggy leaving off the D-day stripes. As a base I used my favorite paint which is Rust-Oleum Metallic Aluminum. I love the look of this paint, it goes on easy and smoothly with a light coat, and it dries to the touch in 2-3 min.

P38-10.jpg



Performance:

The CG is around 2 ½” from the leading edge of the wing. On order to achieve this the batteries sit centered just forward of the CG. This puts them in the bottom of the fuselage under the wing which has the added bonus of adding weight to the lowest part of the plane. That combined with the dihedral of the wings makes it a very stable flyer.

P38-11.jpg


It has a lower wing area to weight ratio than most FT planes, so it cruses around ¾ throttle. This is still better than many other foam warbirds out there. Its top speed is a little better than the FT Sea Duck’s, but not quite as fast as the FT Spitfire or Mustang.

I can’t speak much to the planes acrobatic performance as I tend to fly slow circles, and generally if the plane is upside down while I am flying something has gone terribly wrong. I did however pull off a decent hammerhead turn and something that vaguely resembled a loop and roll. They looked as good as they have in any other plane I have attempted them. When I get video of the plane flying I will have my buddy who spends more time flying upside down than right-side up fly it to see how it does.

P38-12.jpg



Plans:
 

Attachments

JTarmstr

Well-known member
#3
This is my design for a foamboard P-38. There are other P-38 plans people have posted, but one of the things I enjoy the most about this hobby is designing and building planes (almost more they flying them), so I decided to design my own. For this plane I wanted something that was comparable in size to the FT Sea Duck, and could be built in approximately the same amount of time. It didn’t need to be terribly detailed, but I wanted it to look good enough that people instantly knew what it was.

View attachment 112979


History:

This plane is version #2 of my P-38 design. My original design was more squared off, did not have the “radiators” on the sides of the nacelles, and was unnecessarily complicated to build. With what I have learned over the past year I was able to fancy up the design while cutting the build time and complexity. I brought this to Flite Fest 2018 where several people asked for the plans, and you can find them below.

You may notice the nose is a bit smushed, and the right wingtip is bent. The nose is from a taxi test of the plane before I added a servo to steer the nose wheel. I originally planned to control it on the ground with differential thrust, however if you need to turn to avoid something quickly, applying more power doesn’t work great. As for the wingtip, I wasn’t paying attention and walked into a door while carrying the plane.


Specifications:
  • Wingspan – 56”
  • Fuselage Length – 40 1/2”
  • Motor – (2) Emaxx GT2215/09 (FT C-Pack)
  • ESC – 30A
  • Prop – 8x6 3-blade or 10.5x4.5 2-blade (If you can find 9x4 or 5 3-blade let me know)
  • Battery – 3s 2200mah (I use 2, but it will fly and balance with 1)
  • Servos: (4) 9g
  • 6 sheets of foamboard


Preliminary Design:

When I started on this project I knew I wanted to use FT C-Pack motors. I used the FT Sea Duck plans as a start since it has twin booms and runs off twin C-pack motors. I brought the plans for the Sea Duck into AutoCAD and using the drawing below started to make modifications to make it look more like a P-38. This included tapering the wings and adding dihedral. The nacelles are stretched forward of the wing more, made taller and radiators added. The tail modifications are minor, simply reshaped vertical and horizontal stabilizers. The fuselage is drastically different and I started from scratch on that.

View attachment 112980

The plane has ailerons, elevator and differential thrust. The rudder is used for the nose wheel only as I did not design actual rudders into the plane. I decided to keep things simple and use fixed landing gear with no flaps, however it would be easy to add them (maybe in version 3).

As I said, this is my version #2. Version #1 I had a fake “Grill” built into the nacelles below the motor, and did not include radiators on the back of the nacelles. The problem with this is that the large flat surface below the motor gave the same effect as flaps when throttling up and the plane would climb drastically. To address this, in version 2 I left the area below the motor open, and cut vent holes in the side of the nacelles under the radiators for air to escape. When initially test flying the plane with a 2-blade 10.5” prop this eliminated the climbing issue. However, when I put the 3-blade 8” prop on the climbing issue returned. I hope to find a 9” 3-blade prop for the plane that may help the issue.

View attachment 112981

View attachment 112982

When designing the fuselage I went through a few different designs of the nose trying to build it more geometrically and give a more overall roundedness appearance to it. However none of them looked great, so in the end I decided to go with a rounded nose and tapered sides which I think turned out pretty good.

View attachment 112983

After I had the plane together and a few test flights in something seemed missing. It finally dawned on me, spinners. I don’t use them on most of my planes, but I purchased 2” spinners hoping it would bring the plane together, and in my opinion they really did.

View attachment 112984
(Note: The plans have been fixed so the nacelles should be square with the fuselage)


Landing Gear:

The main landing gear is 2 1/2” wheels I bought from a local hobby shop. They are anchored into the wing with the wire bent into a C shape for inside the wing with a matching pattern cut into a piec of foamboard to match. Then there is one more piece on top of that to hold it into place.

View attachment 112985
Note: This image is from a previous writeup, in this plane the wheel axel is rotated 90 degrees

The nose gear uses a 2” wheel with a question mark bend. There are pieces of paint stick mounted inside the nose to reinforce where the landing gear mounts to the fuselage. A wheel collar on the outside of the plane (recessed in the foam) and a steering arm inside keep the gear in place. The arm is connected to the steering servo that is mounted to the side of the fuselage.

View attachment 112986

View attachment 112987


Paint:

After a few successful test flights it came time to paint. I based the paint scheme on the plane Happy Jacks’s Go Buggy leaving off the D-day stripes. As a base I used my favorite paint which is Rust-Oleum Metallic Aluminum. I love the look of this paint, it goes on easy and smoothly with a light coat, and it dries to the touch in 2-3 min.

View attachment 112988


Performance:

The CG is around 2 ½” from the leading edge of the wing. On order to achieve this the batteries sit centered just forward of the CG. This puts them in the bottom of the fuselage under the wing which has the added bonus of adding weight to the lowest part of the plane. That combined with the dihedral of the wings makes it a very stable flyer.

View attachment 112989

It has a lower wing area to weight ratio than most FT planes, so it cruses around ¾ throttle. This is still better than many other foam warbirds out there. Its top speed is a little better than the FT Sea Duck’s, but not quite as fast as the FT Spitfire or Mustang.

I can’t speak much to the planes acrobatic performance as I tend to fly slow circles, and generally if the plane is upside down while I am flying something has gone terribly wrong. I did however pull off a decent hammerhead turn and something that vaguely resembled a loop and roll. They looked as good as they have in any other plane I have attempted them. When I get video of the plane flying I will have my buddy who spends more time flying upside down than right-side up fly it to see how it does.

View attachment 112990


Plans:
Thats great! One of Kelly Johnsons greatest designs and I love how you can use the C pack motors for it
 

Horseman3381

Well-known member
#6
Heads Up RC had some inexpensive 9x5 and 9x4 3 blade props. They only have CW's now though.
They seem to have mostly reverse props... Unfortunately I don't have removable powerpods, so changing one of the motor rotations would be tricky. However I do like the fact that they have them in grey, may need to order a set of those for my Sea Duck.
 

jpot1

Well-known member
#9
Not sure how I missed this thread. Awesome build! I’ve been watching John Overstreets build video but this seems so much more doable!
 

FoamyDM

Building Fool-Flying Noob
#10
@jpot1 I noticed there are a ton of new posts daily. it's easy to miss. (I wonder if there is a "highlight for 24hr" toggle for like challenges or help labels.
@Horseman3381 - me too! I tried. with some success. but mostly nothing I could control. I want to say, the battery hatch doubler was REALLY great for this model. I smear the sides with a thin layer of Hot glue and it was solid!

I mutilated this trying to get it to fly.
I set this up last night using the guts of a Banggood C-17. trifolded block of Standard DTFB with the center section with a motor groove cut works. put them in the nacells.
I found the 300mah batt. that I have for the unit balanced best in the rear top of the fuse. but the board comes Mounted to the bottom plastic plate, sits vertically. and didn't fit right. I had to shoe-horn it in an angle. (this may be my issue).

Time to test. - I placed it on my driveway. powered it up to 50-60% throttle and within 20' it was airborne! they it started to rotated counter-clockwise. turned and nosed into the short grass. Fortunately it is VERY light. 17g, and the motor system is about as much.

I tried a number of things. Motor angle, setting the aileron flaps to counter-roll. Nothing really worked. The problem is I would get a few that would fly straight-ish before it rolled. and this showed so much promise.

This is my Favorite Sim Bird! the micro shows hints at being the same. I'll remount later this weekend and try again.