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g.hendricks(at)sbcglobal.
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 Posted: Sat Jul 19, 2008 7:10 am Post subject: Yak-55M Rudder Counterbalance ?? |
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Yak-55M Owners,
While recovering the tail feathers on my Yak-55M, I discovered that a small counterbalance weight appears to be missing from the rudder horn, and wonder what is in other Yak-55M’s out there. Here’s the deal...
The rudder horn has a large counterweight bolted in the forward part of the horn that weighs 3~4 lbs. About 3 inches aft of the bolted in counterweight is a metal bracket (plate) with two bolt holes that can accommodate a small weight of say 3/8” thick x 1.5 in x 2.5 in (maybe up to 1 lb of tungsten). On my airplane, evidence is that this counterweight was never installed at the factory. After looking at two other Yak-55M’s, I found one with the small weight and one without.
So what is supposed to be there ? Is this somehow a small trim weight installed at the factory, if required. If it is required, how would one determine what is the correct counterweight for a specific installation?
For all you aero majors with stability & control know how, how do I know if the rudder is correctly counterbalanced. What are the calculations.
This airplane has been flying just fine (I think) without the small counterweight, and has a Vne of 450 km/h (243 mph) if that makes a difference. I’ve noticed no adverse control anomalies, but since I’ve never flown a different Yak-55M...have no way to compare.
I recovered the rudder with 3.4 oz heavy weight poly-fiber polyester, and after all the finishes and paint, the rudder weighs 1.5 lbs lighter than the rudder weighed originally with the Russian cotton / dope finish.
Any comments would be appreciated.
George Hendricks
N95YK
Fort Worth
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hkgibby(at)yahoo.com
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| Posted: Sat Jul 19, 2008 10:54 am Post subject: Yak-55M Rudder Counterbalance ?? |
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George,Here is a partial answer to your question:I will try. First, any advice is in no way connected to Gulfstream. Second, I have some basic knowledge but cannot be considered a flutter expert. With that said, the basic problem is to ensure that the center of mass of the surface is far enough forward to prevent flutter at high speed. Don't know the design specs but it is reasonable to assume that individual surfaces were balanced with weight as needed. The rework should be checked to ensure that the center of mass did not shift aft. If the original surface was not balance checked then you have to make an educated guess, compare to another known good surface, or check against a factory spec. Since the new cover is lighter, the cg probably moved in the safe direction (fwd). Do not test above Vne without proper intrumentation and training. Hope this helps. Scott BuetheSr. Experimental Test PilotGulfstream Flight Operations(912) 441-3235 mobile(912) 965-3880 office
Sent via BlackBerry from T-Mobile
From: <g.hendricks(at)sbcglobal.net>
Date: Sat, 19 Jul 2008 10:07:28 -0500
To: <yak-list(at)matronics.com>
Subject: Yak-List: Yak-55M Rudder Counterbalance ??
Yak-55M Owners,
While recovering the tail feathers on my Yak-55M, I = discovered that a small counterbalance weight appears to be missing from the rudder = horn, and wonder what is in other Yak-55M’s out there. Here’s the = deal...
The rudder horn has a large counterweight bolted in = the forward part of the horn that weighs 3~4 lbs. About 3 inches aft of the = bolted in counterweight is a metal bracket (plate) with two bolt holes that can accommodate a small weight of say 3/8” thick x 1.5 in x 2.5 in = (maybe up to 1 lb of tungsten). On my airplane, evidence is that this = counterweight was never installed at the factory. After looking at two other = Yak-55M’s, I found one with the small weight and one without.
So what is supposed to be there ? Is this somehow a = small trim weight installed at the factory, if required. If it is required, = how would one determine what is the correct counterweight for a specific = installation?
For all you aero majors with stability & control = know how, how do I know if the rudder is correctly counterbalanced. What are the = calculations.
This airplane has been flying just fine (I think) = without the small counterweight, and has a Vne of 450 km/h (243 mph) if that = makes a difference. I’ve noticed no adverse control anomalies, but since I’ve = never flown a different Yak-55M...have no way to compare.
I recovered the rudder with 3.4 oz heavy weight = poly-fiber polyester, and after all the finishes and paint, the rudder weighs 1.5 = lbs lighter than the rudder weighed originally with the Russian cotton / = dope finish.
Any comments would be appreciated.
George Hendricks
N95YK
Fort Worth
| Quote: | | _-=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D _-=3D - The Yak-List Email Forum - _-=3D Use the Matronics List Features Navigator to browse _-=3D the many List utilities such as List Un/Subscription, _-=3D Archive Search & Download, 7-Day Browse, Chat, FAQ, _-=3D Photoshare, and much much more: _-=3D --> http://www.matronics.com/Navigator?Yak-List _-=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D _-=3D - MATRONICS WEB FORUMS - _-=3D Same great content also available via the Web Forums! _-=3D --> http://forums.matronics.com _-=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D _-=3D - List Contribution Web Site - _-=3D Thank you for your generous support! _-=3D -Matt Dralle, List Admin. _-=3D --> http://www.matronics.com/contribution _-=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D |
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