101" DTFB B-25 Mitchell Build

[earthsciteach]

I've been planning this one since being inspired by the large fan fold planes at Flite Fest. This build will use the 101" Nick Ziroli planes as a guide for shape and size, but will depart quite a bit in terms of construction due to utilizing different materials.

I'd like to thank Crafty Dan for generously giving me the plans and Wilsonmann for plotting out a set and mailing them to me. I could not bring myself to work on the blueprint plans. But, the plotted set is equally as beautiful and on really high quality paper. I feel like both sets should be framed and hanging on a wall in my house!

The fuselage will consist of a "box spar" for strength with formers attached to provide shape. The box spar will be a combination of DTFB and birch ply. Formers will be attached to the spar for shape and those will be skinned with DTFB. Wings and horizontal stab/ vert stabs will be removable. I'll utilize electric retracts, either of my own design or off-the-shelf if I can find something close enough to scale. Also planning on an operable bomb bay doors, but those are icing on the cake, so we'll see about those.

The entire surface will be covered with light-weight glass cloth and WBPU. I'm going to invite Wilsonmann to my house to do the rivets. ;-D

 

[earthsciteach]

Pics of box spar parts

 

[willsonman]

*giggle*, Under my breath... "sucker". Seriously... bravo for taking this one on. Really looking forward to seeing how you transport it!

 

[earthsciteach]

I'm really looking forward to seeing how I transport it, too!

 

[earthsciteach]

Posting on my phone, so pics are a huge pain at the moment.

 

[AkimboGlueGuns]

This one will be good. Would tissue paper work in place of glass cloth when applying the finishing layer?

 

[willsonman]

I would go with glass for more strength. This is a BIG plane. The plans took up my ENTIRE living room floor with the sofa pushed out of the way.

 

[saiga556]

gonna be a monster.

 

[BanditJacksRC]

I'v seen you bring this project up once or twice, and I'm def. excited to see it's on it way. I'll be following this one... Good luck!

 

[earthsciteach]

Things have been really stressful lately and I have not had time to think much about it. Its going to take A LOT of work to get it done. If I don't get it done in time, so be it. I never complete my rc projects in the time I would like anyway!

 

[jamboree1]

Why worry about transporting it? just straddle it and fly off into the wild blue yonder

 

[Joker 53150]

Glad to see you're getting this one started!

 

[earthsciteach]

Just turn your head….

This is the structural heart of the B-25, the plate that the removable wing will mount to. The two sticks are just acting as a jig to keep everything aligned. Its hard to see, but it is sitting in place over top of one side of the box spar. 3 mm ply will be attached to each side and span beyond each of the two bulkheads to carry the load of the fuselage. That entire assembly will be inside the DTFB box spar.

 

[earthsciteach]

Its been a while since I did much with the build. Today, I'm gluing in cross pieces to stiffen the wing attachment area. You're looking at the bottom of the piece that will be the central structural area. Not much to look at now, but once this is done, the box spar will go together and I'll be able to add the formers for the fuselage. Starting to think ahead to paint schemes...

 

[wilmracer]

Subscribed and watching

 

[earthsciteach]

The stiffeners are on and the sticks acting as a jig are removed. This piece also sets the angle of incidence of the wing. Also cut out the templates for the fuselage formers which will attach to the box spar.

 

[earthsciteach]

These pics show how the box spar will go together.

 

[Flynn]

Awesome Earthsci! /popcorn for the this one. So you obviously plan on making the wings removable, Are you also planning on having the wings separate into 2 (or more) pieces? I really am looking forward to see how you tackle the retracts. I've been toying with adding them to some dollartree foam designs. Good Luck!

EDIT : I just realized you're not too far from me (2-3hours). I might have to drive down to see this bad boy in the air.

 

[earthsciteach]

Hey, Flynn. Come on over anytime!

The thought hit me the other day, I have no idea where I'm going to maiden this thing once its done! Might have to be at FTFF… Oh, the pressure!

I am planning on doing retracts. Don't know exactly how, yet. Minor details, anyway.
The wing will be two-piece. I will probably make the horz stab and vertical stabs removable, too.

 

[willsonman]

Meh, wood frame gorilla glued to the foam. Bolt in the retract, done. Pat, I would never off this unless you knew me but, I'd be happy to maiden it for you. With all the scratch builds I've done over the years my nerves are pretty much shot that I don't really feel it anymore. Honestly though... you should not have a problem. The WL is going just make this thing a powered kite. My field may not be all that big but I'm sure with the WL you could easily c'mon down here to fly her.