Designing your first model

[Erfolg]

Eifon

The answer to your question as to why not swept winged trainers, is, swepping back increases the tendency to tip stall, the more profound, the greater the effect.

I think the benefit from dihedral is dependant on so many factors, it is probably something that does not lend itself to a simple calculation. I am thinking of factors, such as, the CG above or below the wing (lateral position), the side area and disposition of the area, drag on such items as UC.

I do recognise a model with to much dihedral though, a tendency to Dutch roll. I built a electric Tomboy, that exhibited violent Dutch Rolling, until reducing the dihedral by probably 3/4.

I have built a number of models without any dihedral incl. TH Clean Sweep, and a Pularis with no issues at all.

As an aside I built TH Clean Sweep with a V tail, again no problem.

[Eifion Herbert]

After a bit more thought this is what I'm going to do. I have in the garage an old GWS slow stick that is severely hanger-rashed as in the tail is completely ruined. I thought I would take the wings and the fuselage (stick) which are OK, update the old brushed motor and NiCad to something brushless and a lipo, and fasion a new tail. Posibly might make it a V-tail, somehow make the whole thing take-downable so that it can fit neatily into some kind of protective case which can go into a backpack.

I know it's not exactly designing, more like prototyping ( or just fiddling about if we're honest   but I think it might be a fun thing to do, and will probably teach me a thing or two about putting a plane together while not following someone else's instructions.

[Bob Cotsford]

Does anyone remember the Aeromodellers Data book? If I recall correctly it had a blue cover, might have been a graph paper design. It was a modellers almanac filled with little things such as calculating dihedral angles, spar sizes, wire sizes - exactly what it said on the front.

I seem to recall 1" per foot of half span as being about right for high wing rudder controlled models, with ailerons it's more a case of what looks pleasing.

[Erfolg]

I do vaguely remember the book by Ron Moulton.

I do not think it was heavily theory based, more rule of thumb relationships, although expressed as a function. There was another book that used Nomographs (i think that is what they were called), again similarly based. The point was is they worked quite well.

With respects to the thinking in that era, the models were generally free flight, or radio assist some of the time. The models needed to look after themselves, or cope with extreme inputs, of the on off type.

I do not think that from a practical operating aspect, there is the need in this era, to have such large dihedral angles, in some cases non will be required, when using proportional radio.

Edited By Erfolg on 14/05/2013 15:44:56