Billa2.5D

Hey Mike,

I am in the process of scratch building a Cap 232 - as you are aware, the design has terrible pitch to the belly in KE if built to scale dimensions. I was looking over some plans and came across your design of the Midwest 80" CAP. It has a forward canted hingeline. What effect does the angle of the fin/rudder hingeline (w.r.t. the aircraft's datum line) have on knife edge flight in particular and anything else in general ? Does it change pitch coupling or roll coupling ? I remember reading a reference to it in Dave Patrick's book " Aerobatics" but he did not explain what exactly the effect would be as far as I can remember. I am aware that moving the tail plane position lower on the fuse will help in KE and I have found a way to do that without spoiling the looks. But will this help too - any adverse effects ?

TIA,
Aamer

MMcConville

My Feedback: (4)

The forward canted hingeline is scale. It can have some effect on coupeling but I have found it to be pretty minimal. The stab location , the wing location and thrust line relationship are the primary issued. The Cap is worse because of the very high thrust line, low wing and hi stab.

Billa2.5D

Well now that I have your attention I hope you won't mind if I pick your mind a little more. Attached are a couple of plans -well three actually. Option 1 is the basic modifications one would find on most kits (raised wing and lowered tail without losing the looks). Option 2 was done so as to make the tail lower in relation to the thrust line such that the bottom of the fuse is now parallel to the thrust line. This was achieved by stretching the tail section downwards but this gave the plane a bent look as if it is drooping ( tricks of the eye) so I came up with Option 3 where the bottom of the fuse is slightly angled upwards towards the rear without compromising the side area. Option 3 also has the canted forward hingeline. I am building this machine initially for the OS 160 before I do a 50 cc version. Am currently having a blast with a World Models Cap with an enlarged wing at 76" wingspan and a wing area of 1075 sq. in with an AUW of less than 11 lbs( the original was at 73" with a wing area around 960 sq.in and too much dihedral) Which version do you think is best suited to reducing the bad habits of the Cap. ? This Fuse will have a 73" length.

MMcConville

My Feedback: (4)

The differences are subtle and likely the differences in performance will also be slight. I agree though, Option 3 is how I'd do it.

rmh

When I did the Zlin 50 -Dave Brown flew in the TOC in 1976(?) Idid the setup as shown in the third example - just rotated to fuselage a bit which closed the wing/stab gap
Having said that .
My current Cap- is 13 lb 1200sq in model very scale and has none of the futzing for "Caps bad habits".
The reason why -is that built light - they simply have no bad habits .
Also If you use a 25% CG they are still excellent 3D flyers (mine will do the flip over -with down elevator nicely -not rapidly but a nice smooth flip.)
Also it has very little down pitch on knife flight
It is not wildly overpowered - a std ZDZ40 and a quiet JMB can, in fuselage muffler and a 20x10 prop I whipped up which revs fast.
hovers hold perfectly , etc..and easy fast vertical recovery
the key is -keep the weight on a CAP -DOWN-- and the cg a bit forward.

Billa2.5D

Thank you very much for the replies. Work is currently underway on Option 3. As for the CG, I have also noticed that it gives a more locked in feel with a forward CG even in 3D. That is why I stretched the fuse a bit - option to play around with the CG a little more without compromising on the precision. Expected weight of (max) 10.5 lbs at 1075 sq.in. yeilds a wing loading of 22.5 which should have a feel pretty similar to 24.96 oz/sft at 1200 sq.in. as in Dick's model. The current rudder elevator mix on my model is 13% but in actual terms the deflection is little more than 1/8 ". Let's see how things go.

rmh

sounds good - I did an identically sized model with YS 1,4 at 10.5lbs a few years back- working from Mike's original plans from Midwest models I used much thinner airfoils for wings and a 10% symmetrical tail group( foam n balsa)

rene69

Hello Dick,
I'm slowly getting back in RC. It has been about 15 years since my last serious flying. Year ago I bought Hangar 9 CAP 232 for a 1.20-1.80 2C power. Well after all this time I want to get it ready to fly. I remember that someone said that the aluminum gear was kind of soft and I agree. Do you know of anybody that mfg. a replacement? Any help will be appreciate.
I've seen your name in some of the mags that I buy and seems to me that you still are building like always. How do you do it?
I sold my business and retired in Austin, Tx. The weather is not as friendly as it was in California.
Thanks for any help
Rene

at-6 texan

hi guys!!!Unless I'm looking for designs to build the Cap 232 scale 1 / 4 ..... Please if you have any design of the fuselage (from the side, you could top post !..... Thanks!

at-6 texan

up up!!!!...please!

rene69

Sorry I do not have what you need!