View Full Version : Spoilers and dihedral bracing for Bird of Time
10-10-2006, 09:19 PM
I have the ARF version of the BOT and it is pretty obvious that it needs spoilers... So, I was thinking of these: GR931 http://www.hobby-lobby.com/images/grmicrologo.jpg "Teck" Spoilers for 3.5M from Hobby Lobby. My big problem is that the leading edge of the wing is sheeted and I'm not sure what is underneath. Does anyone have a set of plans for the kit and can tell me a bit about what is inside? I'd also like to know how the main dihedral is set as I head a loud crack on the maiden flight and I will need to sure that up a bit. There is now a hairline crack in the bottom center sheeting and that may have been the source of the sound but I want to sure it up none the less.
Anyway, back to the spoilers... Where are they installed? Just aft of the main spar? How far out from the root? I can't find much on the operation of these spoilers, but I think they are spring loaded? Any suggestion would be greatly appreciated...
10-22-2006, 12:18 PM
A lot has been written about spoilers on the BoT at "the other" forum.
A very clear write-up of the problem (and the solution) appeared recently in the RC Soaring Digest Magazine. Go to www.rcsoaringdigest.com (http://www.rcsoaringdigest.com) and look for the 2006 October issue, pages 35-39
10-23-2006, 05:38 PM
Thanks! That gives a glimpse into the construction of the wing. I still want to go with the "Pop-ups". I just can't seem to find any info on them... I suppose if I buy a set, I'll have all the info I need!
10-31-2006, 09:24 AM
From what I can see on the graupner site's unclear picture (!?) they seem to be selling the spoiler flaps with hinges. The rest of the work is like the RCSD article. If that's the case, it seems to me a waste of money. You can just as easily fabricate a set of spoilerflaps yourself.
10-31-2006, 04:20 PM
Yeah, hard to tell... I was under the impression that they just pop straight up and are not hinged but you are right, if they are just hinged then I might as well just make them myself. Still, the pop up ones would be cooler...
10-31-2006, 08:58 PM
I found this at Grupner's web site: http://shop.graupner.de/webuerp/servlet/AI?ARTN=1000.250 There is a PDF of the manual as well: http://www.graupner.de/fileadmin/downloadcenter/anleitungen/1000.250.pdf. The english is towards the bottom. At any rate, they look like they pop up with a scissor action. They are not spring loaded but I bet that could be added. That way, they would only need a single thread to operate. Otherwise, I might use a nyrod that exits the center of the wing with the servo mounted in the center of the wing like an aileron servo...
I know I could just build spoilers, but I don't want to muck up the wing too bad and these sit in a well 11mm wide by 16mm deep by 250mm long. They weigh in at 1.4oz.
11-10-2006, 09:27 PM
At the Nats this year a flyer had an eBOT with a single spoiler in the center of the wing. It was held down by a spring and raised by the arm of a servo mounted in the spoiler bay.
11-11-2006, 01:23 AM
Ya know, I thought about one in the center, but I wonder about the diehedral braces and such... On the other hand, the routing and such would be easier...
11-11-2006, 01:41 AM
I have an article I wrote on the complete conversion. It was done in MS front page and I am unable to post it. If you would like me to try and email it to you, send your email. It is very large.
11-11-2006, 09:58 PM
Thanks Bob! It's email@example.com
12-08-2006, 05:44 AM
I like their pop-ups but its true you could make them yourself. They have a small surface footprint when closed and look well made. They can be mounted all the way out on the center main wing or at least a point where the inboard part of the spoiler is outboard of the horizontal stab.
By all means don't cut into the D-Cell forward of the main spar. Mounting the spoilers directly behind the spar would be a better choice structurally. Sorry to hear you got a wing problem. So far mine has been strong enough to endure a few cartwheels and landing lumps- and that G Loading I call flying! :D.
The problem with a spoiler in the center of the wing is the horrendous turbulence the tailfeathers have to operate in with that giant burble of major turbulence upwind of the control surfaces!
The only ARF E-Glider I've seen with a center spoiler is a V-Tail but it too would experience a reduction of control and stability with the brakes open.
04-20-2007, 05:29 AM
I finally finished the spoilers and the repair on the center section! Just so I don't duplicate everything, it is in the originl build log I did. Check it out here => http://www.wattflyer.com/forums/showthread.php?p=184036#post184036
05-12-2007, 03:13 AM
Hobby Lobby is out of the thin hinge type of spoilers, where else can you get them??
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