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Scratch Built 58in TBM Avenger

#1
Hello,
First off, this is my first post I have made on the FT forums. Over the past few months I have designed and built a 58in Grumman TBM-3 Avenger out of dollar tree foam board. I wanted to post as my build progressed but never got around to it thanks to school, sports, etc. So, I present to you a basic summary/build log of what I had done. This was the first plane I have ever completely scratch built (yes i know I'm crazy for picking this plane first) but I am no stranger to build the FT way. I have built a Viggen, mini speedster, and a Kraken along with a few large balsa planes. Sorry for some of the upside down pictures my Iphone does that. Here it is:

I started with a set of three views with cross sections and started editing them into plans. I also did a lot of research into the versions of the plane and into scratch building. What helps a lot is seeing a real plane and I got some good pics of one at EAA and of the rear turret at the USS Enterprise in NY. I did all my plan editing with a calculator and Microsoft paint, not the ideal tools but it worked.
tbf planpart 2.jpg
IMG_1709.JPG
Here are some examples of the plans (I will probably upload the plans later)
tbf planpart wing.jpg
After I made the plans to my liking I printed them out using a scaling program and one that prints in tiles. The program is literally called tile print and it is free! Then I started making a prototype of the fuse and wing roots out of some cardboard I had laying around.
IMG_0883.JPG IMG_0886.JPG IMG_0887.JPG IMG_0888.JPG

I changed the plans while building it to make them work better in the design. After I was done with the prototype I played with different ways of covering the plane from Monokote to foam board and after some more research and trials I went with foam board with one side peeled off so it bends easy. Then I started building the air frame.
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Well, that's all for today. I will continue the story later this week hopefully and will continue as I modify and continue the build past its current point. I also have some time lapses from my Mobius of the build stages which I will put up soon too. Stay tuned!
 

Jaxx

Posted a thousand or more times
#3
Welcome to the forum!

You've done some great work with this design. What software did you use to create your plans?
 
#5
Well I am back and writing the next part about the Avenger. I put servos in the wing as I built the wing and in between building parts of the plane I researched power systems for it that would allow me to carry what I wanted with plenty of power. I used the free version of ecalc prop calculator which works fine but doesn't have all the full functions. Then I ordered similar electronics, this is what I got:
avenger motor Characteristics.png avenger motor Characteristics2.png IMG_2125.JPG
After I installed the electronics I started sheeting the plane in the foam board. After the first few pieces I figured out that you need to use small pieces from former to former.
IMG_2055.JPG IMG_2062.JPG
I also built into the design a scale bomb bay which in this model can carry an object roughly 15in by 3in by 3in, like a Pringles can for instance. It opens and closes with two halves unlike the real TBF's accordion bomb doors but it works nicely. This will be one of those videos I will post later.
I finally got it all together a few weeks ago and it looked great. I re-did the control wires as they were too thin for the large control surfaces and couldn't take the force. This was very hard as the plane was sheeted making the servos hard to get to.
IMG_2215.JPG IMG_2216.JPG
After I got it to this stage were I had all the electronics working and trimmed out. I also added in expo at this time to my liking. Finally I started thinking about paint these past few days as the weather has finally gotten ok in Wisconsin. I decided to go with something totally different than anything else (not that you see many rc avengers in the first place). After WW2 the Avengers were sold to many countries all over the world and remanded in service in some of those countries well into the 1960's. 7 Avengers surprisingly went to Cuba but I could not find any pictures of them. So I went with one of 3 TBM-3E Avengers that were bought and operated by the Brazilian navy in the 1950's. They were used aboard the Brazilian carrier Minas Gerais which had previously been the HMS Vengeance and the carrier served until 2001. These Avengers had a paint scheme requiring minimal painting on foam board but also looked different. avenger paint base.png
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I have decals printed and just need to put them on. I hope to maiden the Avenger this weekend if the weather cooperates with me. After that all I have to do is figure out how to design and build the rear dorsal turret shell.
That's all for today I will try to keep you all updated on the build and if you have any questions, comments, or suggestions, throw them out and I will do my best to reply.
 

beanie

Junior Member
#6
that looks amazing! great job on the design/plans/build! and good luck with the maiden. any chance of video? would you be willing to post your plans? i'm sure you'd get a bunch of interested builders.
-beanie
 

SP0NZ

FT CAD Gremlin
Staff member
Moderator
Mentor
#8
Wow! You did all that with MS Paint and a calculator? That is impressive. Your Avenger looks fantastic. Can't wait to see some flight video. Best of luck with your maiden flight.

BTW, whereabouts in WI are you? My son and I are in Fond du Lac.
 
#9
@beanie: plans and videos soon to come. I will put up some time lapse build videos and some other stuff of the plane along with flight video. As for the plans, I will post after putting in all the mods to them and after proving the plane flies.

@sponz: I am in cedarburg and fly with the astrowings in port Washington
 

SP0NZ

FT CAD Gremlin
Staff member
Moderator
Mentor
#10
Nice. I know where that is. Lived in West Bend when I was a kid (well a much younger kid anyway). ;) Just an older bigger kid now. :D
 
#15
Sorry the weather didn't cooperate so I couldn't maiden it. I will hopefully do it this friday as that looks to be the best weather. I am putting on decals in the meantime.
 
#16
Mighunter, Amazing man! I was planning this for my first scratch built as I didn't find many examples of this airplane. This was about a week ago, and now I stumble across your build! I guess I'll just need to build it from your plans :)
 
#18
@heavy313:
That is exactly why I built this plane, there isn't many of them. Yes I plan to add the ball turret and also I am going to make a clear canopy for it with the ribbing in it.
 
#20
It Flew!!

Well, this past Saturday I got up and it was sunny and 70 out with no wind. So I loaded up and took it to the field. By the time I got out to the field(its right by the lake) the wind was at 3-5 from the north east. I still took it up. With a headwind it took off very quick and flew ok, the elev has so much surface area so it was extremely pitchy(which is what I thought would happen. I have to modify the control lines for the elev so I can dial it back with some more trimming and expo. Also my landing gear wire was a little thin so with a hard first landing the right gear bent slightly, but they are 8in long so I was not surprised. But yeah, it flew! I will be posting the pics and a video once my dad sends them to me :)