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#1
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LS3a Airbrake question
I have a problem with my LS3a. During flight, from 90 km/h, on both
wings the airbrakes comming out from the wings slightly (some millimeters), a little bit higher during ircling flight, during pull- up and at higher g-loads. Yesterday I have tried the following during flight: I have pulled the airbrake handle very slowly back from closed and locked position untill to the point that I felt resistance and looked the airbrake covercaps on the wings. It was interesting that fulling back the airbrake handle 5-I0 mm the airbrake covercaps went back on both wings to their good positionthe. I think it means that the over-center (self-closing) is not correct. Does it mean that the ocer-center is incorrect ? Is there any way to set the over-center ? |
#2
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LS3a Airbrake question
It sounds like your spoilers aren't set correctly. They should fully
seat and then pull down on the little springs (under the spoiler cap) about 1mm or about one dime width. You can check this by pulling up on the spoiler cap and sliding in a dime. Do this at 4 places along the spoiler. Then close and lock the spoiler. Now look at the closed cap.............if it is sticking up anywhere, it did NOT pull down the required 1mm (dime width). Adjust the linkage, probably at the spoiler box to make the spoiler pull down more. This adjustment is made on the rod that goes from the over-center mechanism to the spoiler, NOT on the rod going TO the over-center mechanism. JJ Oh, yeah, remove the dimes from your spoiler box :) wrote: I have a problem with my LS3a. During flight, from 90 km/h, on both wings the airbrakes comming out from the wings slightly (some millimeters), a little bit higher during ircling flight, during pull- up and at higher g-loads. Yesterday I have tried the following during flight: I have pulled the airbrake handle very slowly back from closed and locked position untill to the point that I felt resistance and looked the airbrake covercaps on the wings. It was interesting that fulling back the airbrake handle 5-I0 mm the airbrake covercaps went back on both wings to their good positionthe. I think it means that the over-center (self-closing) is not correct. Does it mean that the ocer-center is incorrect ? Is there any way to set the over-center ? |
#3
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LS3a Airbrake question
On Apr 28, 5:36*am, JJ Sinclair wrote:
if it is sticking up anywhere, it did NOT pull down the required 1mm (dime width). Adjust the linkage, probably at the spoiler box to make the spoiler pull down more. If, as the OP suggests, if the over center mechanism is not set correctly the spoiler caps may pull down the correct amount and then relax as the linkage goes further over center. I had a discussion with Waibel about the airbrakes on my ASW-28. Mine go much further over center than the factory specs say they should. The solution is to shim the pad where the over center bell crank contacts the spoiler box. To find out how much over center there is at the current adjustment you can put temporary shims on the pads. Slowly increase the thickness of the temporary shims until the airbrakes just stay locked. Then remove the temporary shims, measure them, subtract the factory spec over center measurement, and fix appropriate thickness shims in place. I used aluminum shims sandwiched with double sided tape for the temporary shim stack. I am not familiar with the LS linkage so the specifics for changing the over center adjustment may be different. However, all over center mechanisms must use an over center stop and the position of the stop controls the amount the mechanism relaxes after passing the over center point. You will need to know how much over center is required. Reduce it too much and the airbrakes will come unlocked in flight. Andy |
#4
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LS3a Airbrake question
Thanks for your answer, unfortunately I do not understand fully you:
"Then close and lock the spoiler. Now look at the closed cap.............if it is sticking up anywhere, it did NOT pull down the required 1mm (dime width). " It would be nice to discuss it with you off-line, I have a drawing about the airbrake mechanism from LS, I could send it you. |
#5
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LS3a Airbrake question
Sorry, I forgot to mention my email:
It would be nice to discuss it with you off-line, I have a drawing about the airbrake mechanism from LS, I could send it you. |
#6
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LS3a Airbrake question
Recommend you take your LS-3 to a mechanic that understands
sailplanes. Probably not a good idea for unskilled hands to be adjusting the spoiler caps or over-center stops. Copy the responses you got, it may help with the adjustment process. Cheers, JJ wrote: Thanks for your answer, unfortunately I do not understand fully you: "Then close and lock the spoiler. Now look at the closed cap.............if it is sticking up anywhere, it did NOT pull down the required 1mm (dime width). " It would be nice to discuss it with you off-line, I have a drawing about the airbrake mechanism from LS, I could send it you. |
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