P-38 Pusher MJ - Build log

[matjey]

It's been a while since my last post to this forum. A couple of thing have hold be back down from being actively involve with RC. But now the sun start shining again and I'm up for a great start.

This time around, I've done designing and building up the P-38 model with a pusher setup motor. Pusher setup has been one of my preferred setup as I tend to broke my prop on regular basis due to bad landing

Pretty much everything is on my published article here: https://www.flitetest.com/articles/p-38-pusher-mj-another-variant-of-twin-boom

View attachment 104916

The build will have below spec:
Motor: 1450kv
Prop: 8x6
Batt: 1800mah Lipo
30A ESC
3 x micro 9g servo


I would not touch on the build process in details but rather to write on the outcome of the flight report after have successfully maiden it. The build process take less than a day in fact it just took me 4 hours from cutting the depron and assembling it all together.

The first maiden with had launch can be a bit scary if this was your first time. Watch out for that prop, don't get yourself cut. To me, it is a breeze for the maiden. The plane flew right of my hand and gently climb up against the head wind. Not that mild banking left or right as normal warbird like P-51.

Not much of the aerobatic that I can perform on this baby. It is the aileron throw is not that big enough and regarding the design of it, I planned it to fly slow and calm. Well, if you want to be able to perform trick with this plane, one might need to increase the aileron throw and shorten the wing depth.

If you happen to build this one for yourself, please tag me along. Would love to see how it goes. Feel free to comments, suggest or critics. Hopefully I can improve my design skills in the near future as currently I'm working on another project. A Grumman A-6 Intruder using pusher motor setup.

Cheers

 

[rockyboy]

Nicely done sir - both the plane and the plans! :applause:

 

[jamboree1]

I only took a few pics of my build but i will post specs and what mods are needed and improvements when I get home.

 

[DamoRC]

Nice - love the way you captured the essence of the plane in such a straightforward design.

DamoRC

 

[jamboree1]

Here is my build pics and maiden, if there is interest i will give a few details on the build.

https://www.youtube.com/watch?v=UJPjfKFuhhs

 

[jpot1]

Jamboree - looks great. Nice design Matjey! I was thinking of shrinking this by 15% to handle the diff between 6mm and DTFB thickness. Also making the nose more FT like with B fold. Details would be great.

 

[jamboree1]

Jamboree - looks great. Nice design Matjey! I was thinking of shrinking this by 15% to handle the diff between 6mm and DTFB thickness. Also making the nose more FT like with B fold. Details would be great.

Actually you don't need to resize, i just cut on the inside of cut outs, and the wing/fuselage cut outs are way to small, you'll need to do your own trimming. I'd build again in these steps, build wing and pods first, build bottom and sides of fuse. Do not glue in top fuse panel as the wings drop in as opposed to sliding in the fuse. some trimming also needed on whats labeled "wing covers" I added to ailerons 1/4" on inside to 1/8" on outside, increased elevator cuts by 1/2" as far as motor mounting goes i'd either inset the motor mount into the fuse at least 1" or just trim an inch off the plans. This should be done for better balancing as i had to use a 2200 3 cell all the way in the nose to balance it using a park 400 size motor. sorry if this isn't detailed yet as my index finger recently got a prop strike from aforementioned plane.

 

[matjey]

Pertaining to what jpot1 posted, The B and A Fold method as what the Flite Test plan consist of; I will improve it in the future design. Or maybe I'll be creating a variants of plan for people to choose from. The point I didn't include the 'folding' technique onto the plan is due to me wanting to reduce the space of the paper being laid out during printing. However, it would be nice to have variants. Thanks for the highlighted.

jamboree1 - Glad that you enjoyed building and flying it. The flight report is important to me to see how the aircraft flew from other builder perspective. It will be my benchmark in producing the better approach and design.

 

[matjey]

Nice - love the way you captured the essence of the plane in such a straightforward design.

DamoRC

Thanks DamoRC. It is one of my objective; to have an easy build and get it flying in lesser time.

 

[matjey]

Nicely done sir - both the plane and the plans! :applause:

Thank you rockyboy. Let's get building it too

 

[jamboree1]

I did forget flight report her, i will just C&P from what i wrote on RCGroups. Ok Matejy, here it is. I did build with larger aileron and elevator. This was a very uneventful maiden, 1/2 throttle take off and it's gone, 2 click down elevator and 2 click right aileron was all that was needed on mine. Most likely the elevator adjustment is due to motor angle, i think mine could use a bit of angling as it tends to gain altitude with heavy throttle. The plane tracked strait and true, it didn't fee light, nor did it feel heavy while flying. Aileron rolls were predictable in either direction while using elevator (didn't use elevator first roll) loops can be however you want them. all rates were set on low 70%, I haven't tried high rates nor expect to as it performed great as it is. i flew it as slow as i could without touching elevator, no sign of tip stall. Landing was uneventful also, came in low and slow, cut throttle and pulled up. thanks for a sweet design.

 

[jpot1]

Jamboree- how many inches of dihedral did you use? I’m updating plans for DTFB and trying to include more realistic wing cutouts. Mostly updated but was going to add a gauge like the typical FT plans. Can you estimate the wingtip height with the other panel flat in the same way the FT gauges typically work?

 

[jamboree1]

Jamboree- how many inches of dihedral did you use? I’m updating plans for DTFB and trying to include more realistic wing cutouts. Mostly updated but was going to add a gauge like the typical FT plans. Can you estimate the wingtip height with the other panel flat in the same way the FT gauges typically work?

It's hard to tell now while assembled but a measurment i could do, with one wing flat on table the opposite wing tip is at 2" off the table. but a typical FT gauge for a similar size plane would work

 

[jamboree1]

I hove more stick time in today, still a great tracker, stays where you want it. Motor off glide was excellent. inverted flight is a challenge, required 3/4 of elevator input to stay there.

 

[jpot1]

Good progress this weekend. Cut a portion of a wing to get the wing cutouts and then have been building from the resized 5mm foam plans.
Booms have a bbq skewer embedded within for strength. Also used a popsicle stick to join the wings. Went with 2.5” of dihedral.

 

[jamboree1]

Looking good jpot. I'd add a bamboo skewer to the horizontal stabilizer if you haven't yet, go from boom to boom, i have slight warping now.

 

[jamboree1]

I got around painting mine, so now i'll probably crash it.

 

[jpot1]

That looks great! I'm thinking about a silver paint scheme with the invasion strikes. I thought about the skewer in the hstab but was worried about weight. I'll go ahead and add it now per your suggestion.

 

[jamboree1]

jpot, if you happen to mount your servo for the elevator like i did... USE THE OTHER SIDE.. lol, i wasn't thinking about it torque roll is to left, so add that little bit of servo weight to the right side, doesn't matter much really though

 

[jpot1]

Finished mine off today. Added some pieces of zip tie with the ends cut off on the bottom of the booms and vstabs to hopefully prevent some foam rash.