No one else will do it.
11710 forum posts
For years I have had a soft spot for Gee Bees, particularly the R1/2. I built a Gee Bee model D. But, yes the but, I much prefer the out and out racers.
I know they are almost a cartoon, big, bulbous, garish, school boy paint jobs. Yet strangely they really followed the science of the day theories, Particularly the teardrop was the best low drag body shape. Models being tested in the wind tunnel of I believe the University of New York.
Over the years, I have sought to cajole Peter Millar to build one. I know he has a soft spot for midget racers, having published a number of plans (free in some case from RCM&E). I have built a number of his designs. Yet I have never manged to convince Peter, via "Peter Millar asks what is next"?
Rather churlishly he suggested why not design on yourself. So this is a least the design phase, can I do it?
The first thing was to get a reasonable size drawing of the plane.
I have done this. Next decide how big should it be. I decided the length would have to be no more than 36", for the longest member. This decided that the Fuz was the limiting factor. Next what scale? By 10 was convenient but small, by 13 would just be within 36", but I am not superstitious, so it is by 12, I cab live with that.
As you can see, that the sections on the drawing are not the best for bulkhead positions. But that is all I have. Also the model is heavily tapered. The up side, is that the body is pretty much round for most of its length. The downside, there is a transition from round to a line stern post.
It has been the transition that has occupied me for the longest time. I used the method (mainly) of interpolation between sections at various angles, ie 45 degrees as one and so on.
Next I need to put in a wing section, which will be E205. The reason being, from use, I know it has a very good low drag value, from about the minium sink to high speed, as used when penetrating (in competition gliders). I expect that there are better wing sections available now, although I have no experience of them other than HM 32. The scale section is extremely thin. Plus as a flyer, I am in the category of being a very mortal, ordinary, to sub ordinary flyer.
Once I have the wing in, then I will start putting in bulkheads, the working out their shape.
|Andy Joyce||02/04/2020 16:18:23|
228 forum posts
Try downloading Inkscape (free) its a relatively simple drawing package that would allow to print or send off your parts of for laser cutting. Takes a night or two to get the hang of using it but thereafter its easy to draw blended curves or indeed trace objects from a pdf drawing.
|Nigel R||02/04/2020 16:53:46|
3744 forum posts
Some inspiration perhaps, although it is a Z1 replica...
The knife edge at around 3 mins is particularly impressive for a 1930s racer!
Landing is a little bumpy too. Visibility an issue I suspect.
Edited By Nigel R on 02/04/2020 16:55:33
11710 forum posts
I could use Autocad and Autosketch at one time, I find it takes me to long to look up how to do things, as I do not remember. The other big issue is that my monitor is quite small, measures 19", which is a pain for this type of work.
I did find when I had a period of evaluating CAD work (as part of my job, long before retirement), unless you do mods to a design, the first drawing takes longer than on a board. Although, CAD would generate the splines etc, far easier than manual drawing.
The big gain would be the CAM bit, in this case routing or laser cutting. I am hoping to avoid needing that route, but time will tell.
I might not even build it. I already have a drawing of a Fokker V29 done, a Gotha 224 and a Yellow Canary (midget biplane racer). I am not convinced that the Yellow Canary would be controllable by me, without gyro assistance.
|Andy Joyce||02/04/2020 17:42:22|
228 forum posts
Agree Erfolg unless your using CAD every day it takes far too long to draw simple shapes. Having just built a laser cutter I paid well over the price of a kit trying trial cuts and incorrect CAD drawings for a bird of time build before I got the hang of using it. Hate to think how much balsa has gone in the bin. Still the next order from SLEC arrives tomorrow having just been ordered yesterday.
Need to complete several models in the hanger before I start another but that me all over. See an interesting build subject and off I go with cutting balsa.
Bird of Time has now been put to one side whilst I complete a 1/4 scale Tiger Moth but as soon as I hit a problem sure I will get diverted to drawing up a new model.
Edited By Andy Joyce on 02/04/2020 17:43:22
|6423 forum posts|
Drawing on a drawing board is superior for our purposes - quicker and cheaper. With the added advantage it's full size and therefore you can place actual components on the drawing to ensure they fit.
I see that there is a pretty good QED plan on Outerzone which has the sections all worked out. Not really cheating just to enlarge them to your required size - at least it would look right. But perhaps the fun of working this out for yourself is the real buzz that you want......
|Peter Miller||02/04/2020 18:48:33|
10959 forum posts
Well Done Erfolg. Keep it up.
I have never used a CAD program although I do use Compufoil for designing the wing.
I do find that one can see the shape much better on the drawing board, It is amazing howmuch difference a slight change to a curve or angle can amke to the shape.
My Book on designing can help with drawing sections etc. (Still available from Sarik)
I can guarentee that once you have designed your QED you will never stop designing again.WE need more designers.
11710 forum posts
Peter you have made a very relevant point about scale. Many, many years ago, when we were drawing by candle light, or we just went home. I drew up a special tank, on a Ao sized sheet. their may have been details on another sheet.
This set of tanks went into a very large room. By the time they were made I was the design office representative on site. It was just another bit of kit, in a large facility. The tanks had arrived and been installed months earlier. For some reason i went into the location of these items, looked around, half wondered where they were, as the shear enormity and scale of the items sunk in. They went on for ever, wherever you looked, be it along or up, as you needed to look up to get them into view.
Now perhaps just as astounding, my tanks were based or that should be influenced by a previous design, approx half the size. I did undertake stress calculations on a few what I thought as critical components. With hindsight, who in their right mind would let some one in their twenties design such things unsupervised (although there was a team leader). Now I would baulk at such a task, and I do not think i would let some one loose on such a task, if I were their manager, without a lot of input from an experienced qualified engineer. How times have changed and what a wuz I am now in my dotage.
Yep, seeing what you are designing is important, even if your imagination is good. I am not convinced my own is.
Edited By Erfolg on 02/04/2020 20:21:52
Edited By Erfolg on 02/04/2020 20:22:53
|JOHN MOSLEY 2||02/04/2020 22:18:46|
|26 forum posts|
Yes on the same note I remember drawing a baseplate for motor and gearbox as junior draughtsman and going down on the shop floor to look for it. It was a rather larger that I expected but when motor and gearbox where fitted to was all in proportion. I think CAD is worse for that in getting a loss of scale.
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