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Old Feb 03, 2012, 09:03 AM
Chuck 'Em and Chase 'Em
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Can LDS be done on a DLG or is top drive as close as we can get?

Guys,

I saw in the MultiTask F3X forum a discussion on LDS.

From what I can see it is nothing more than a top driven servo where instead of having a control horn and pushrod stick out the top, the horn is buried in the hinge and the pivot is along the opposite surface as the hinge. This is as far as I understand it.

Are the wings thick enough or are the servo arms small enough, etc. for us rto be able to do an LDS setup in a DLG?



http://www.rcgroups.com/forums/showt...&highlight=lds


example of LDS
http://www.skipmillermodels.com/Espadita_p/espadita.htm
http://www.rcgroups.com/forums/showthread.php?t=1239669
http://www.rcgroups.com/forums/showthread.php?t=1239669
https://plus.google.com/photos/10826...945?banner=pwa

Frank
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Old Feb 03, 2012, 09:46 AM
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It looks no different that a servo horn that is more solidly held. The limitation to this is both the thickness of our wings as well as the thickness of the airfoil at the hingeline. IMHO, this is just fancier and weigh more. Otherwise, identical.
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Old Feb 03, 2012, 09:54 AM
Chuck 'Em and Chase 'Em
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I like the idea of nothing sticking up, like in an RDS setup. I think we could come up with a lighter weight version but if it is mechanically impossible, then why bother?

I figured the LDS would satisfy the guys looking for nothing sticking out of the wing, the guys who complain that RDS can be sloppy might be better pleased with this and it could offer alternatives when wing thickness is an issue.
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Old Feb 03, 2012, 11:41 AM
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ouch! Thats a lot of load concentrated on the flap/hingeline. Not so much with thicker wings though.How the heck is the pin removed at the rear end?

Looks like a headache to me
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Old Feb 03, 2012, 11:44 AM
Chuck 'Em and Chase 'Em
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I think the control surface pin is slid in from the side of the surface when deflected.

Is that the pin you refer to?
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Old Feb 03, 2012, 11:53 AM
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Quote:
Originally Posted by Fly2High View Post
I think the control surface pin is slid in from the side of the surface when deflected.

Is that the pin you refer to?
Yes, thanks for that. SOO a two pc wing is a must?
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Old Feb 03, 2012, 11:58 AM
Chuck 'Em and Chase 'Em
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I think you can deflect the surface and then insert the pin
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Old Feb 03, 2012, 12:13 PM
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The physics annoy me. If the pins from front to rear are not aligned it will bind and if its not tight there will be slop. Very little gap though.
What happens to the hinge end of things if the servo end is at SDC [side dead centre. lol] and the flap gets knocked. ouch! It seems novel to me.
Im waiting for someone to come up with a spring loaded flap and some sort of cam to activate it but im not holding my breath. lol

I really like the Legends system by Sharper Dave for A RDS substitute
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Old Feb 03, 2012, 12:17 PM
Chuck 'Em and Chase 'Em
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I was thinking of a pull spring for flaps but how strong of a spring would you need and could it handle flutter?

I guess the regular pushrod (bottom or top) and RDS is the only available options......
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Old Feb 03, 2012, 01:13 PM
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My thinking is that the weight involved to incorporate the LDS system may very well be equal to the weight involved to install a spring and related reinforcements that could handle the flutter issues.

Thanks for the link , its interesting to ponder new methods.
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Old Feb 03, 2012, 01:39 PM
Oleg Golovidov
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I agree with Chris and this comment from David:
Quote:
Originally Posted by djklein21 View Post
On another note, Linear Drive System. Lame name. It's a conventional linkage with beefed up links and clevises. I bet it ... suffers the safe high shear loads on the output shaft and hinge line ...
I don't see why it deserves a special name, and "linear" definitely does not fit.

If we simply keep reducing the servo arm and the control horn, we will eventually be able to hide the control horn within the aileron thickness. The forces will proportionally increase. If the current control horn arm is about 8mm, to hide it within the aileron it has to be 4mm? So the loads on the servo shaft, the pushrod, and the hinge will double. More wear and tear, and even a little compliance in the servo shaft or hinge line will show up as a big slop in the aileron. If the components are strong enough, it is possible. For example, Sirius had aileron horns almost entirely within the depth of the aileron, because the ailerons were thicker than on Polaris or other wings.
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Old Feb 03, 2012, 02:42 PM
Chuck 'Em and Chase 'Em
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Thanks Oleg. Now I can understand it is not a desired direction to take. Exactly what I was looking for.

I would guess then that the choices we have for control are the top or bottom drive, RDS and the way Shaper Dave does the Arrow/Legend planes.

Frank
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