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Old Jan 09, 2009, 10:33 PM
flyboy320 is offline
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High start and covering question on my Big Bird


I have a Skybench Big Bird (100" span) nearing completion and will be covering it soon. When it comes to covering, if I want to keep it light, would Ultracote lite be the best for this bird?

I will need a high start for it, and I will just be using this for sport, no competition and I am at somewhat of a loss as to what type and what size high start would be best suited for this size glider?
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Old Jan 09, 2009, 10:44 PM
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As far as covering, you shouldn't need anything "lite". Regular Monocote works well, and provides some stiffness. Most folks on this forum seem to agree that Monocote offers that whereas Ultracote doesn't. That's what the consensus seems to be anyway!!
A standard hi-start should handle your BB just fine. Give it a little time, others will post on here as well and give you more opinions and probably some links so you can look at all the options and do and buy what you think will work best for you.
Good luck and have fun!!
Old Jan 10, 2009, 03:48 AM
Wylie Shaw is offline
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Covering - Hi-Start


You can use monokote for the center panels and transparent mono for the tip panels. Or Ultracoat lite for the tips....

you can find one of the best hi starts made here

www.aerofoam.com
Old Jan 10, 2009, 08:08 AM
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Thanks for the help guys

I would like to try a design similar to this one. I belive the wing design is called a "D" section, so it doesn't need additional strength that a covering would provide. Is this correct? If so, what I would like to use is Ultracoat lite for the fuse and tail to keep the tail as light as possible (rudder and stab is not an open design, but a solid piece of balsa), and perhaps the wing as well, or if the wing would benefit from the extra strength, then Monokote for the wing, and Ultracoat lite for the rest of the bird.
Old Jan 10, 2009, 11:45 AM
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My 100 inch Big Bird weighs 41 oz and launches well with the 2M Hobby Lobby HI Start.
I covered the wings and tail surfaces with Transparent Flouresent Red Ultracote! After a couple years it has faded to a rather nice mercurochrome color. CG is right where Ray recommends!
Old Jan 10, 2009, 12:40 PM
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On a plane this size the weight difference between "regular" and "light" coverings will barely, if at all, be noticable in the air.
Old Jan 10, 2009, 01:43 PM
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One thing that might help, Monocote lately has proven to be a little more difficult to apply without wrinkles. The Ultracote seems to go on easier, especially for one who might have little experience with coverings of this type. Since you will be hi starting, the additional stiffness is ( IMHO ) of no real consequence. Use the Ultracote and let us know how you make out with it!!
Old Jan 11, 2009, 11:27 AM
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Quote:
Originally Posted by varoman1
My 100 inch Big Bird weighs 41 oz and launches well with the 2M Hobby Lobby HI Start.
I covered the wings and tail surfaces with Transparent Flouresent Red Ultracote! After a couple years it has faded to a rather nice mercurochrome color. CG is right where Ray recommends!
Wondering if you could attach a picture of the servo layout and placement in your Big Bird to get the C of G right? I am about to start to figure out where I should place my equipment so this would help out a lot

Also, thanks for all the help guys, much appreciated...
Old Jan 11, 2009, 12:54 PM
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I do not have a photo, but here is the layout from the rear end of the nose block:

-One inch long space for weights. Approx 1 oz.
-4.8 volt 900ma nimh AAA battery
-Two standard size Airtronics 102 servos in line (not side by side) I mount onto 1/8 ply
frame.
-Hitec 555 receiver on end and wrapped in their foam.

Behind the first fuselage former, I have a hatch just like the Skybench photos. Here I have a Hitec 225 servo for the spoilers which are controlled using a flexible sullivan .030 cable in its yellow colored tubing. The spoiler servo pushes the spoilers open. My spoiler horns are a ball link setup. For my rudder and elevator control rods, I used the sullivan carbon fiber black rod in white tubing.
Let me know if you need any additional info!
Andy
Old Jan 11, 2009, 01:01 PM
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Thanks very much varoman1.

Makes perfect sense. I have two micro servos mounted in the wing and they are directly hooked to the spoilers.

I was wondering about pushrods as well. It seems the wire ones supplied have a fair amount of flex, so was thinking about Gold-N-Rod or something similar. How does the sullivan carbon fiber black rod in white tubing work? Is there much friction in the bend where it exists the fuselage, or is it fairly bind/friction free?

Thanks again.
Old Jan 11, 2009, 03:05 PM
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The Sullivan carbon rods (Precision Rod #581) work quite well and tolerate the slight bend at the rear of the fuselage where they cross. They have been in my plane for over 4 years without any problems! They are not as slippery as the .007 carbon in etched teflon that some of the others use. I have not had any problems with temperature changes affecting length. Try to have as gentle bends as possible.

The most important item to me in building this plane is to set the surface of the stab perfectly parallel to the bottom of the wing surface from the spar back to the end of the trailing edge. If your incidence is off; you will fly with up trim on the elevator and try to compensate by moving the CG back. If your incidence is off in the other direction you will be upset with stalling and then try to keep the nose level by adding nose weight.
Sorry, I did not mean to ramble. The Big Bird is an excellent flying plane. You will love it!
Andy
Old Jan 11, 2009, 03:23 PM
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Thanks again Andy. I am sure I might have some other questions later on, but this should keep me busy for a while!!

Now I just have to find a good rx to use with my DX7 tx to go in this. I am thinking about either a AR500, AR6000, or the AR6200. I'm keeping my eyes out for a used one on the forums here.

Cheers.
Old Jan 11, 2009, 03:35 PM
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PM me anytime and I will try to help!
Lots of good info in Sailplane talk as to which AR receiver is loved most!
Check https://www.rcgroups.com/forums/showthread.php?t=975869

Andy


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