UStik,

More food for thought... I've always believed (perhaps incorrectly) that more concentric models (flying surfaces closer to the thrust line) tend to fly better roll maneuvers due to their indifference to upright vs inverted flight. Because of this, I've also assumed (again perhaps incorrectly) that they have a more gentle stall behavior (i.e., less wing dropping) with less tendency to snap out of the sky. It is with this in mind, that my "gut feeling" (I'm just a fledgling designer...) was telling me to bring the surfaces closer to the thrust line. Aside from knife edge performance, is this also why Hanno lowered the stab on the Dalotel? (I wish I had a copy of his plans.)

I'm not sure what you mean by a "small drive" but perhaps you're referring to lower torque/thrust/power platforms allowing one to build lighter models? I'm fairly certain that one can build just about any aerobatic model "light enough" these days. If we consider the wing loadings of typical aerobatic/3D electric models today (even small models), they have loadings that are exceptionally low (high single digits/low teens). Just by glancing at the GP 40 plans, I can see how I can take out a pound without even thinking much about it. 2 lbs would require a little more work but I think also doable for a 4.5 lb/550 square model. In fact, I don't think the kit will ever be built because of this but the plan might...

In short, what I'm getting at is my question as to why you don't believe in a smaller scale version (from any standpoint)? I certainly don't expect the 25 to necessarily be a good proxy of the flight performance of the 90 but it does help to at least verify the laser cut plus; perhaps a little flight experimentation too.

Switching gears, I'm pretty sold on your recommendation for Eppler airfoils. If I understand correctly, if you had a recommendation for a 25 size model, you would recommend E168 while for the 90, you might recommend E169? Or perhaps, compared to the full scale, both these models are "small" and would be better off with E168?

I have high expectations of being able to reach 9.5 lbs on the Dalotel. For the CAP, at what I'm converging on being 81", I'm not so sure. I'd like models with ~1000 wing squares and because of the CAP's wing planform, large span is needed to reach that area. The main unknown in the weight equation (as you suggested) is how much the wing & stab will weigh if built with foam cores (I was hoping for cores on both models). I'm fairly confident in that I can design/build a pretty light fuse airframe. A little math might give us a good estimate of the flying surfaces weight (considering that classic 60 size thick airfoil models can be built to ~25 oz wings...)

As a very crude estimate, do the following figures seems realistic for a ~1000 squares model?

Wing = 40 oz (2.5 lbs)
Fuse/Empennage = 48 oz (3 lbs)
Equipment/Power = 64 oz (4 lbs)

If not, perhaps I need to reconsider things. Good to know about the location of max thicknesses.

I don't quite follow your last paragraph - would you mind clarifying?

Thanks for the contents of your PM's!

David.