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-   -   Foamy GeeBee (http://www.Wattflyer.com/forums/showthread.php?t=73521)

abborgogna 04-08-2014 09:19 PM

Foamy GeeBee
 
I am currently laying out a foam profile version of the GeeBee R2 for flying at my local park. My question is what is the best spar material for a 36 inch wing span and what is the best way to install it? I have seen everything from laying the spar on the foam and gluing it down to cutting completely through the foam and gluing the spar between the two halves. My guess is it really doesn't make much difference aerodynamically but from a strength and aesthetic point of view it does. Any opinions will be greatly appreciated. By the way I am using 6mil depron for the building material.

CHELLIE 04-08-2014 09:55 PM

Quote:

Originally Posted by abborgogna (Post 944891)
I am currently laying out a foam profile version of the GeeBee R2 for flying at my local park. My question is what is the best spar material for a 36 inch wing span and what is the best way to install it? I have seen everything from laying the spar on the foam and gluing it down to cutting completely through the foam and gluing the spar between the two halves. My guess is it really doesn't make much difference aerodynamically but from a strength and aesthetic point of view it does. Any opinions will be greatly appreciated. By the way I am using 6mil depron for the building material.

Hi :) The best spar material is CF square tube, cut a slot so the 6mm CF lays flush in the wing, use some clear packing tape on one side to cover the hole, spread some 5 min epoxy on the CF, lay it in the cut out grove, then cover it with some clear Packing tape, that will make for a very very stiff and strong spar. you only need one spar brace, in the pic i used 2 braces because this was going to be a very over powered plane.

http://www.rcfoam.com/carbon-fiber-s...ube-p-838.html

http://www.Wattflyer.com/forums/atta...2&d=1188794571
http://www.Wattflyer.com/forums/atta...0&d=1188801153

http://www.Wattflyer.com/forums/atta...2&d=1188807050

CHELLIE 04-08-2014 10:01 PM

I painted the wing so you cant see the CF Brace on my scratch built Gee Bee

http://www.Wattflyer.com/forums/atta...1&d=1393396781

abborgogna 04-12-2014 06:33 AM

Thanks for all the help guys, today I started cutting out the parts. When I get them all cut I will post some pictures. I started with a design that comes from Igor Burger, he is the current world control line aerobatic champion. His design was for indoor C/L aerobatics. I took the basic design and reworked it for R/C. With a little luck it should fly well as a park flyer.

solentlife 04-12-2014 08:16 AM

I build a lot with 6mm depron.... and CF is not easy to come by where I live.... so I use BBQ bamboo / pine skewers laid into slots, same principle as above.

What I like about using wood.... is there is a limited amount of flex and when they do break - you can in fact glue together again unlike CF which splinters....

Nigel

CHELLIE 04-12-2014 09:07 AM

Dang Nigel :eek: You must crash your planes Hard :concern: I have never crashed a plane and splintered the CF brace on my planes :D LOL Take care, Chellie

fdnyjery 04-12-2014 04:58 PM

MS.Chellie ; Just a note to say Thank You for all the Great information you give out about the Hobby, I went back and checked out all your posts since 08 and really you should write a book . I have learned, so much from all your posts. I sure do hope you write that book about foamies and all your knowledge of all aspects of our hobby. Once again Thank You very much for all you do for the hobby!
All My Best Jerry aka FDNYJERY

abborgogna 04-18-2014 09:02 PM

1 Attachment(s)
I have made some progress on the Gee Bee. Below is a picture of it.

CHELLIE 04-19-2014 04:30 AM

Quote:

Originally Posted by fdnyjery (Post 945277)
MS.Chellie ; Just a note to say Thank You for all the Great information you give out about the Hobby, I went back and checked out all your posts since 08 and really you should write a book . I have learned, so much from all your posts. I sure do hope you write that book about foamies and all your knowledge of all aspects of our hobby. Once again Thank You very much for all you do for the hobby!
All My Best Jerry aka FDNYJERY

Thank You Jerry For the Complements :$ I have been in this Hobby for a long time :D Take care and have fun, Chellie

CHELLIE 04-19-2014 04:34 AM

Now That Looks Sweet :) Give the motor about 1 to 2 degrees of down thrust, no right or left thrust and give it a try, R or L motor thrust can be added later if needed, but a Flat wings always need down thrust to load the main wing and make them fly stable with out pitching up and down, Keep up the nice work, Chellie

http://www.Wattflyer.com/forums/atta...5&d=1397847705

abborgogna 04-19-2014 06:06 PM

Hi Chellie
Thanks for the good words. The original design the Igor Burger did for indoor control line aerobatics already had the down thrust included in the design. I transferred the down thrust directly from the original. I was going to put in some right thrust, but will hold off until I fly it. Last night I found the formulas for locating the MAC on an elliptical wing so now I can set in the CG. I asked Igor for a suggestion on the CG, he really didn't have any idea. All his experience is in C/L, by the way, Igor Burger is the current world champion precision aerobatic control line flyer. I also asked my friend Larry Renger of Cox engine/airplane design fame for his opinion, Larry suggested starting out at about 20% of the MAC so that's where I will start. Unless of course you have a better suggestion. All help is greatly appreciated.

As for the plane, the changes from the original design include going from 3mm depron to 6mm depron, the addition of a second spar, redesigned landing gear, a larger motor to carry the extra weight, and the addition of ailerons, rudder and tail wheel for steering. The original also had air dams on the wing to slow it down, I left them off the R/C version.
Andy

abborgogna 04-21-2014 11:27 PM

OK so today was not a great day for the GB. Although it did get airborne I had to shut power down very quickly or risk loosing the plane. It rolled down the runway nice and straight, it lifted off nicely and then to my surprise it started rolling right. The way our runway is laid out the right bank took the plane toward the crowd and out of view. So I shut down the power and hoped for the best. A few scratches on the wing tip and minor damage to the landing gear. All in all the plane came out it very well. All repairs have been made, and while making the repairs I started looking for reasons for the turn to the right. I came up with two very good reasons, first the ailerons had a slight right roll built in. My mistake, I should have caught that before the first attempt, and second vertical balance was definitely biased to the right. The receiver, servo wiring, ESC and most importantly the battery were all attached to the right side of the fuselage. This weight imbalance led to a roll moment to the right. I have since made sure all the control surfaces are dead level and I moved the battery over to the left side. I checked the vertical CG and it now looks good.

Weather here in SoCal is not suppose to be very good tomorrow, lots of wind predicted. So the next test flight will have to wait until Friday.

Wish me luck people.:)
Andy


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