Keil Kraft Bantam

I wasn't going to build anything else for a while but browsing outerzone I spotted this model and thought it would be a interesting thing to build and convert to rc.

Originally designed and drawn in 1955 by AH Hatfull it was initially called Anzac but due to pressure from the new Zealand government it's name was changed to Bantam.
Looking at the plan it's quite clear the original would have had a very short lifespan, it's built like a rubber powered Model, a couple of 1/8th spars in the wing and tiny braces are ok for a model powered by a couple of strands of rubber but wouldn't last long with diesel power even though the plan calls for that to be supplied by such mild engines as a ED baby, frog 50 or Albon Dart or Merlin.
First task is to redraw the front end as I plan to use this lovely little used ED Bee series 2, swings a 8x4 and has a lovely exhaust crackle.

paul
Very 'period'.
I would have thought using an ED Bee you will have to strengthen a bit more than the nose as you will be installing twice the recommended power of say a Frog 50 although having said this I note the series 2 Bee produced a peak of 0.068 hp (50.7 W) according to the 1955 Aero Modeller test.

It does show how far things have come as 50W (7A on a 2s) would be a pretty modest figure for even a small brushless electric RC plane today. In fact such a motor, 10A ESC and a 1000 mAh 2s would be no heavier than the Bee!

Your quite right Q, I'm beefing up the engine bearers up to 1/4x3/8 rather than 1/4 square and they will faired in into the fuselage with balsa. The fuselage is built on a crutch with sub formers added after, I'm planning to plank the first 3 bays below the crutch to stiffen things up and give something to hold on for launching.
You really need to take a look at the plan, it's very odd in places, the wing and fuselage are very lightly built but the fin is built like a brick outhouse!
The notes show the prototype weighed 6.7oz with a Albon Merlin.
Don't think I'll get near that but I'm sorting of aiming for 10oz, I've just been given some 6 micron Mylar that I'm going to cover it with ( double covered with tissue) that should be fairly light and puncture resistant.
Oh and your right about the Bee, it is rather lacking in umph ( being 1958 and in such nice condition I only run it rich and under compressed) but it is torky.

paul d
Had a look at the plan.
The fuselage formers look to be drawn 3/32 whereas the ribs are 1/16.
I suppose the tail fin is robust simply because the fuselage terminates short so it in part supports the tail plane.
Good lick creating all those 1/8 x 1/8 closely spaced slots in the lower formers!
Finally with a heavily under cambered wing section I suspect it will tend to be a 'one speed' plane with a sensitive CofG position that has to be 'just right'.

I've got a cunning little tool for notching formers, I'll post a pic later, it's all part of the fun for me!
got a few jobs on this morning but hopefully I'll start cutting later...watch this space.

At 1/8 x 1/8 it does make me wonder why AH used stringers at all on the fuselage underside.:huh:

They are so close together that I bet 1/16 sheet would actually use less wood and probably lighter. It might be a bit more difficult to apply but then I suppose Albert H (an interesting story) was very much a 'stringer' man.

He was just stringing you along! [badass]

I agree Q, sheeted sub formers would be easier, something to consider.
Didn't get a awful lot done yesterday, 6 nations rugby got in the way! I did however get the first 2 formers cut, cut from "gabon plywood ", noticeably lighter than birch ply but just as stiff, local model shop put me onto it.
Years ago I dabbled in miniature wood carving and bought a set of tiny chisels and there what I use for notches, one on the right has been ground to 1/8th", one on the left is a standard 1/4" job, razor sharp there perfect for tricky little jobs like this.

I added brass end caps that allow me to use a jewellery hammer if needed.

Ah!
Very neat but I am pretty sure Gaboon Ply is heavier than even the hardest of hard balsa.

It is indeed, it's only for the first 2 formers ( the ones the bearers and undercarriage attach to), the rest are 1/8" balsa....

Got the main formers, crutch and spine cut today, think I'm going to reduce the radius of the sub formers by 1/6"th and sheet the bottom ( thanks for the idea Q).
just realised I need to notch the spine!!!

6" rule for scale ( very worn, had it since I was a apprentice.)

paul d
As it is not really structural and if you could find light enough balsa block you could actually make the underside solid and simply sand it to shape. You wouldn't need any of those little formers either.

no that's cheating!

ok gents I've got a conundrum.... the builds going well, top half of the fuselage is getting there ( pics once I've trimmed the stringers flush), As I said the model was designed around a .5cc diesel ( frog, Albon, ED Baby etc) but not having such a motor to hand I moved bits about in order to use a ED Bee, this has involved moving the firewall back, moving the bearers apart etc.
Well last night I was offered a new in box and never run DC Dart ( Albon in all but name), Ive said yes to it as frankly it was a bargain,so my question is do I run it all? do I re-adapt the model in order to accommodate a engine it was originally designed for or do I carry on and use the Bee? It does look rather big when offered up, the fuselage while deep is very slim......

paul d
My view is leave the Bantam as is.
With only 0.5 cc you really will have to be wary of weight.
Ok for free flight (6.7 oz) but if you get to 10 oz you will need the power of the Bee.

If the Dart is new save it. Its not running it that is the problem but the risk of irreparable damage if it crashes.