...at least one way anyway.

  I've always wanted a scale appearing WWII B-25 "Mitchell" stunt model. I've gone over designing and building a B-25 in my head for years now, but I just haven't gotten around to building one. There are some existing designs, but none as scale in appearance as what I'd like. Paul Delgatto's design is very close, and a perfect size, but it's just not quite what I'm after. For one, mine would have to have the proper gull wing, Delgatto's doesn't.

 (The following is copied from a reply that I made to Pat King in his F-82 "Twin Mustang" announcement in the forum Vendors Section. While writing, I thought it may be of interest to some others.)

 I'll roughly describe my hypothetical B-25 design here. This is how I designed and built my 64" PBY Catalina stunt model...
 
 Depending on the chosen full scale subject, there will always be slightly different ways to modify and end up with the desired result. While designing think scale, but pay very close attention to the "stunt devil" sitting on your shoulder and let him influence things all the way through.  
  
 Starting with a "clean sheet" stick diligently with true to scale outlines but play with size relationships between various components. First, pick a desired wingspan, say 56", and print off an enlarged full size scale three-view at that dimension. Be sure to start with a detailed, quality three-view, like on the order of a Paul Matt drawing or similar. Save and set aside the fuselage outline as is. Then, in the case of the B-25, "cheat" or add to the overall wing chord slightly, including the flaps. This is to sneak in some additional wing area but you want to stop before taking away noticably from the scale outline or appearance. Do the same with the stab/elevator and also add in a little more span, essentially you're just enlarging the entire stab/elevator assembly.
 
 Now, take a clean sheet of paper, draw a long horizontal line and mark in the desired moments using the "new" wing/flap/stab/elevator chord dimensions. Take your saved scale fuse outline and lay over it. You will likely need to adjust the fuselage length to fit things where you want them, just make adjustments for the best overall scale appearance/stunt compromise.
 At this point thrust lines and wing/stab height relationships can also be subtley adjusted without detracting from the scale appearance. You may find that you'll want to "section" some height out of the fuselage outline, or not. Go for it if necessary, but keep the top and bottom outlines true to scale. Spend good time getting the fuse proportions just right in comparison to the flying surfaces to maintain the overall scale look of the model. What you should essentially end up with is a scale fuselage with proportionally larger flying surfaces, all with scale outlines.

 This certainly isn't a complete description of the process, but just my own general approach and thought process. It is very possible to design a model that appears very scale but will also be a suprisingly good stunt model. The best of both worlds in my opinion.

Hi Wayne,

This is an excellent thread.  I have had help from Ron Burn, one of the two best scale stunt builders in the universe along with Al Rabe, and this is basically what we have done to a design I have always wanted to build.  We found that with this subject not much had to be done with sizes, mainly a change to the airfoil and some minor changes to the stab/elev.  It is very interesting what you can come up with.  And as long as you build it with it being a stunt model in mind, it can still be light enough to perform great.

Thanks for your post!
Bill

 An airplane that I think would make a great twin engine stunter is the Heinkel HE-111. If you look at an accurate three-view it's a natural, even with exact scale dimensions and outlines. Take a good look at the top view, it's a "no-brainer" that it could be a great stunter. Pick a favorite airfoil and run with it. If you want to get real serious with it just enlarge the stab/elevator a bit and then get it trimmed for the NATS.

 With this basic design approach there is an endless list of potential subjects, even civilian designs. I think it's Gordan Delaney who recently finished a Bellanca Viking that is a beautiful example.

Gordan's incredible Bellanca is Classic legal, designed by James Young, Model Airplane News, Oct 69.

Keith

Might take a look at PJ Rowland's Lancaster.

 That thing is pretty awesome, and an absolute monster. Would be really cool to see it fly.

I'm very pleased to find this thread and such august builders.
I've just started building a 'scale' IL-2 profile stunter ... of a kind. If you're not familiar with the IL-2 it's this thing: http://www.airpages.ru/eng/draw/il2_42.shtml
My sons (10/12 year olds) and I are new to CL flying, though I tried this game a long time ago with my father with little success and I wanted a means of creating relatively quick to build planes with limited costs. So the fuselage is made from 25mm thich XPS foam and .8mm hard balsa sheeting:





The bellcrank will be mounted in the Fus above the wing and the engine mounts will be 25mm x 12mm hardwood inlet into the front, with a light ply doubler back to the bellcrank and wing to hold the old K&B 40 I have.
The wing is the challenge. In comparison to my other planes this thing is enormous! It will be around (hang on I'll convert this to inches) 52-54" (but it could be more) and I was planning to use a style of wing construction as used on the EZE25's we're making for the boys. This is a foam LE, balsa ribs and dowel TE - no flaps, they will be on a future version. My question is on the tip thickness and wing section. The EZE .25 uses a slow-combat style section - is this a reasonable starting point? Also the tips will need to be thinned considerably over the EZE .25 - is there anything I should be wary of in doing this? I imaging the outer tip section will be 3/4" in thickness and the root is 45mm...or close to 1-3/4"

An airplane that I think would make a great twin engine stunter is the Heinkel HE-111. If you look at an accurate three-view it's a natural, even with exact scale dimensions and outlines. Take a good look at the top view, it's a "no-brainer" that it could be a great stunter. Pick a favorite airfoil and run with it. If you want to get real serious with it just enlarge the stab/elevator a bit and then get it trimmed for the NATS.

Me 110,, and it would look great next to my 109,,

Brett I am slowly working my way through Al Rabe's work, but I will note that my goals are very modest in comparison to Al's work and competition is not on the horizon. All the advice we have been given is that bigger models fly better in local conditions and we plan to go this way.
Phil thanks for those tips on the wing - I want to stick with un-flapped wings as I am a beginner. I will measure the chord dimensions when I get the chance and will have some more information. The tail is of quite low aspect ratio, but seems large enough to my uneducated eyes. Do you think the sizing is reasonable for the K&B 40?
I will take the Perry carb off it and will machine up a venturi on the lathe and I have a few spare Enya needle valves of the right size.

Welshman Noel Stephenson had three semi-scale Spitfires published in Aeromodeller years ago,

Noel designed a few excellent looking scale stunters. Martin Baker, and maybe a Miles, come to mind. He really had the knack of making them look realistic, while still  being geared to stunt. I never knew he was Welsh.

What is it Bill?

Hi Wayne,

The model Ron and I have been working on has up until now be a super secret, top level security level clearance, for your eyes only project.  But I will let the cat out of the bag, no one will catch it but you .............

It is a VERY, VERY scale TBF Avenger sized for a .61 piped set up.  The pipe will be hidden in the torpedo bay and the extension will come out where the .30 cal stinger did.  Big fuselage built using his techniques, as to the best I understand them.  The wing will be built in a custom Lost Foam fixture from Bob Hunt, fully sheeted with the proper wing outline and dihedral.  The only major change is the elevator hinge line.  With a throttle, it could be entered in scale.  But with the stunt airfoil and natural moments, it will be a killer stunt plane! (it will probably take me a month to come up with the greenhouse! LOL!!)

Don't tell nobody. 

BIG Bear
RNMM/AMM

My profile Avenger, designed by Don Hutchinson, is now in carbon with several coats of clear. With another good sanding using 320 paper, I will able to cover the wings. It is getting close to assembly.

In keeping with my personal tributes, the nose number will be 911 and there will also be references to FDNY, NYPD, USS Cole and Benghazi.

I applaud Ron and Bill for working on a full bodied Avenger.

Wayne, I hope to see the build thread when you get it started!  That does look like a cool subject for a stunter.

You can't run straight flaps on a cranked wing -- are you going to use articulated flaps, or flaps just on the outboard sides of the nacells, or what?

If you were using 0.8mm plywood it may be adequate, but I don't think that size balsa will stand up.  2mm "feels" about right to me.

25mm x 12mm by what?  I'd use traditional profile engine bearers going back most of the nose, and of a wood that's as close to the maple mounts that are used here in the US as can be.  I'd use whatever thickness is right to span the fuselage, by 3/8" (10mm?).

I'd also cap the top & bottom of the fuselage with something.  My preference would be fairly thick balsa, so I could sand it round -- but a sharp-edged profile fuselage will fly just as well: the air won't care in this case.

Sorry Tim I did not see your comments until now.
I have capped top and bottom of the fus with 2.5mm balsa. The nose will have a ply doubler either side back to the bellcrank box.
The engine bearers are 25mm to match the fus thickness and they are then glued to the ply doublers either side of the fus. The engine bearers are approx 120mm long I think, I would have to check and work has kept me away fromt eh workshop for too long. The wood is Australian oak - a hardwood.
I could add another thinner doubler, say 50mm wide, either side of the fus in 2mm balsa if you think that would help.

Sorry Tim I did not see your comments until now.
I have capped top and bottom of the fus with 2.5mm balsa. The nose will have a ply doubler either side back to the bellcrank box.
The engine bearers are 25mm to match the fus thickness and they are then glued to the ply doublers either side of the fus. The engine bearers are approx 120mm long I think, I would have to check and work has kept me away fromt eh workshop for too long. The wood is Australian oak - a hardwood.
I could add another thinner doubler, say 50mm wide, either side of the fus in 2mm balsa if you think that would help.

I had not realized that your fuselage was so thick -- I saw the 25mm, and thought you were just putting blocks under the engine mounts!!!  What you're doing sounds like it'll work, although it may be a bit heavy.

Depending on how far along you are you may want to stick with what you have.  The last hollow fuselage I built used 3/8" x 1/2" bearers, had an all-solid nose to the back of the wings, then an open truss structure with 1/2" square balsa around the edges with 1/2" x 1/8" trusses.  It used 3/32" balsa sides, with 1/8" poplar plywood (I think) doublers in the nose, and a 3/8" balsa tripler on the inside of the nose for vibration damping and shape.

Of course, the thing weighs a ton...

I'm wondering if you wouldn't end up with more strength for the weight if you used 10mm x 12mm bearers, then backed them up with a hunk of 13mm balsa slab (if such a thing could be obtained -- I don't know what the standard sizes are there).  I'm thinking that you'd have a member that has the hardwood for holding the engine, plus a hunk of balsa for rigidity and vibration damping, all sized so that in the end it matches the thickness of your foam.

I weighed the fuselage today. The fully covered foam, engine mounts and ply doublers and the scales said 255gm, which google says is 9oz. There is still the bellcrank and box to add plus finishing, so perhaps another 1-1.5oz?
I have no idea if this is ballpark right weight or heavy, perhaps someone can tell me?