So what is Weiss Kaninchen 2, it is a rebuild of Weiss Kaninchen. Why you may be asking. Because I crashed the first!
The original was a +1.6m glider/sport model using a 480 motor with 1200 Sanyo Nicad. It was underpowered, but respond well to flaperons and elevator control. The stall occurred at about 40 feet, pulled out quickly at about 45 feet.
So what is the rebuild.
1. To be a sport model, capable of loops, fly byes etc.
2. More power and lighter battery
3. Small enough to take to Scotland, when visiting my daughter (N0. 1).
4) To be prettier than original, to look something like the Club 20 Darra and similar pylon racers. It will not be a pylon racer though, probably not enough power for one thing, light wing loading for another.
5) to use the surviving parts, Wing, tail plane, and err that's it!
This build will emulate the Douglass Dauntless not! It will be built with the knowledge I will crash it, the major question is when. The build quality and finish will aspire to reach the average ( if possible).
So when will I start, today. I have got out my lining paper, drawn with great precision, my vision. I have calculated all relevant features as you would expect from a Bsc(hons), CEng, MiMechE engineer, yes you guessed it (must buy milk for breakfast).
I will keep you all posted (must get back to pulling drains, up to DPC now, the kitchen extension, or east wing, moves foreword with the speed of a ruptured duck, on crutches).
The attached images are of drawings for the Weiss Kaninchen and a De. Vampire (30") that was to be built until this rebuild got in the way.
The Weiss Kaninchen 2 is below. It is essentially the same as the original, whereas No. 1 was a rectangular box, with the wing sat on top. The new arrangement, more attractive body will have some advantages and yes a down side. It will now have a vee tail as the Art Chester "Sweet Pea", the original fin was ugly and I think that the original elevators will surfice (CG may need to be brought foreword).
Advantages
1. Turtle decking, means that the compression members at the top of the fusalage of the original will not be needed. Blue foam will undertake this role.
2. Potentially more room to place equipment.
3. might be considered prettier.
Disadvantages
a) Increased cross sectional area (3 inches square is now 7).
b) increased weight
Any way drawing done, now is the time to start cutting that timber and hewing that plastic.
I have started by assmbling all the good bits? All the rest has gone into my waste bin.
The good
The bad
A fundemental issue with Weiss Kanichen 1, was the poor power to weight ratio. Although the 480 motor was geared (2.5;1) and the motor pushed hard on a 8 cell Sanyo 2/3 SC at +10 amps, the model was lethargic in the climb phase. There was quite a bit of heat apparent after any flight.
It is intended to put this right with a suitable brushless motor with lipo.
Typical construction, for me. Comprising of balsa sides, from 2" balsa sheet, 1/16 side sheet re-enforcement from nose to rear of wing, 1/16"*/1/8" spruce strips on the bottom of fus. side to take any tension loads, through bending (rough landings) and blue foam turtle deck to take compression loads.
Blue foam is available from all reputable "Builders Merchants" so they say.
I buy mine from "Sheffield Insulation", it is an insulation made by Dow Corning.
Dow Corning Floormate X200
50mm, 8*4 feet
Cost? £11.20
It is great for wing tips, turtle decks etc. I have seen almost complete airframes made from it.
Some time ago people made wings from it, using 1" thick sheet. George Stringwells book "Soaring" gives a detailed methodology. No hot wire cutting involved.
I have now finished the shaping of the fusl. No effort to shape, the real drag is waiting for the glues to set. It does not appear to need any filling prior to covering.
It is my intention to use glass cloth with water based varnish from Wickes. I have undertaken a few comparative trials with Z-Epoxy. The results have not been easy to compare with precision. But using observation and non numeric testing I found
Both seem to attach the cloth with equal firmness
More coats of varnish are required to build up a similar finish(3 against 2)
Varnish is more flexible than resin
Both finish to roughly equal smoothness
Weight of finish appaered the same using digital kitchen scales
Varnish finishing is a lot faster and is very convienant, wash brushes in water, varnish dries in approx 2 hrs.
Cost of varnish I would guess is a lot lower than Z-Epoxy (£7 per 500ml).
Now to get cloth, brushes, scissors and varnish out.
The glass and varnish covering has gone well. It has all been done in a day. One fixing coat, plus twwo filling coats. Possibly should be lightly cut back to provide a key for a paint finish.
I had not realised it but there appears to be an additional advantage to this method, the underlying colours remain true (pretty much so). Whereas epoxy can appear to darken some what (when applied over colour). This trueness could be advantageous, particulaly with ply type finishes, where the vibrancey of some colours is lost.
I have found that coloured inks (drawing/airbrush) are particularly good. There is no measurable weight gain (not without laboratory scales). The colours are really vibrant and complex effects are possible without to much difficulty. It appears at first sight that this meathod could provide a clear coat type finish. I must experiment some more, on a new model.
I think that some of the ready to fly models have shown how to make light strong models, using ply. It reminds me that the Sean Bannister Algebra 1 was a ply box, as essentialy was the Sagittas (using 1/8"), yet the undouted strength and competion sucess, never transfered into the mainstream.
I have jsut completed the assembly of the wing, tailplane body.
As a temporary measure the wing has been assembled as a one peice, as per original. Although abot 70mm has been lost in the centre section. If the model is sucesseful, (and that depends on your interpretation of sucess), i will make it into a 3 peice to aid transportation , when visting the far north of the UK.
I have know got my motor for the model, a Tower Pro Bm 2409-12 max watts 200, 1570kv from BRC. On a 8*6 propeller
I would have potentially preffered a Overlander Thumper at about £19-20, the smallest one is supposed to turn a 9*6 and greater at about 200w.My problem there was no dimensional info or performance info available.
Looking good Erfolg. Interesting about the differences, ( or comparative lack of them ) between the varnish and epoxy covering. I am tempted to try the varnish with some very light weight nyloncloth which I have in the odds box to cover and strengthen a Ripmax "Alienator" which is in the "to do" pile.
I acquired it cheaply a year or so ago, to replace one which was re-kitted thanks to a PM lockout. That one I had covered in nylon and 2 part laminating epoxy.
At our Friday night club night, one of the members was talking about epoxying a model. I suggested water soluble varnish, saying I had used the Wickes stuff.
Another member said, "Oh I use B&Q water soluble varnish" (sic). It appears he had used it for some time, and recond it was as good as the Trade Product sold through the model trade.
There was me thinking I had been adventurist in using Wickes, and was taking a risk. I guess there are many alternatives which are effective, being used by modellers, but they do not tell anyone. So the wheel gets re-invented.
The trouble with the trade stuff via the model trade is:
To day was the start of the resumtion of the "big build".
So it was off to the local timber merchants to give them a BOM, for new kitchen and garage roof. The size of which will rival Crystal Place when complete. I won't know if she (who must be obeyed, the master of all the universes) is in the kitchen, if i am at the other end, it will be so large when finished.
Ohhh its the model build section, yet more senior moments.
I have made a start, rear locating pegs and front nylon bolt arrangements have been installed, to hold the wing to the body. Best one I have done for years, of course the others were no great shakes. Yet one job of the list.
I have started on the vee tail clevis/horn arrangements. I tried to find a commercial assembly in the model shop (Webbs at +20 miles away), I was not sucessful. So I have had to make my own. I do not know if there is a simpler way, as my own is quite taxing for me. I have attached a picture of the assembly in making.
I tap the ball in clevis m2.5 and coresspondingly cut a m2.5 thread on a bike spoke. Screw the ball on to the spoke and start bending. To finish I file the end that goes into the elevator, flat. There must be a simpler way. I am fortunate that I have the equipment that my farther left after his death. My mother wanted to junk all his tools, I have saved them. Dad would have made a better job, but that is way of the modern world, very few true skilled tradesman left.
Yes It is finished all but the replacement of an aileron servo, check the balance, wait for a good day. As they say "Once more into the ether, my friends".
The rudervator linkage went well, see attached picture
The motor is an inrunner as can be seen, it is located at the rear by a ring of ply, the mounting disc is a friction (transition fit, good old engineering term) and some removable stops to prevent forword movement.
The finish to the body is just Humbrol paint sprayed on using a Badger airbrush/spray gun. It is translucent, as no undercoat has been applied, and the paint is very thinly applied. For a "Bits A" I am not prepared to spend any more time, until it is proven to be OK.
The question is would I have done anything differently. The answer is, yes I would. Some of the features are not as good as they could be ie the push rods from bicycle spokes, carbon fibre would be better and that is before it has flown.
There is an issue of balance, so nicads will be used, where as Lipos were planned, lighter back end needed.
I still have an issue with the propeller before I can fly, at present it is a Perkins offering, the blades will have to be changed to Aeronauht or Graupner. Why blades are inadequate for Brushless power. Any way I intend posting a message on ther forum on this, to get hopefully more infomation, on alternatives.
Now it is time to decide what to do next, perhaps the Guillows P47 conversion or the Dehavilland Venom.
Looking at the first entry 18/10/07, it has taken a long time to the first flight!
Many aborative belly flops, caused by not enough power, damaged servo, dry solder joint ( who made it? not me), to much elevator throw.
But at long last a sucessful flight, as on rails. Having a high differential on airolon, has made a big difference, no up, only down, reducing the elevator, prevented me from stalling it (even at high speed I stalled it).
The power thing was about loading the prop up with a 9 inch to give 150w against the 8 inch in the BRC literature which drew just over 100w against the nearly 200w specified.
Any way, now to rebuild my circa 1970 flying wing glider to electricity.
As they say in Wigan or is it Keswick "Ende Gute, alas Gute"
denotes 
.
