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Mechanical Retracts

Old 08-31-2002, 01:44 AM
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Default Mechanical Retracts

I can't find a text/instructions for mechanical retracts. Should the push rods from the retracts go as straight as possible to the servo arm, or should there be a slight bend at the arms? My retracts, with a hitec retrac servo grunt and groan about mid retract and have often hung up. I quickly lower them and keep on flying. Have pulled the wells and cleared all binding. The retracts themselves have no binding and the servo is smooth. This is a hanger 9 P51. My email is [email protected]. Thanks to all
Old 09-01-2002, 03:31 PM
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Default Mechanical Retracts

Well is sounds like something is binding.
What happens sometime is the retract seam smooth when your pushing and pulling the wire manually, because you are pushing the wire straight in and out, when the servo rotates it moves the wire at an angle to the retract mechanism.
Try this if the connector where the clevis conects is pointed down try moving it 90 degs. so the clevis is parallel with the servo horn.
Also try some lithium greese on the shaft. that will help smooth it out as well

The only bend you need is at the servo so the wires dont hit each other

Good luck
Old 09-02-2002, 12:40 AM
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Default Mechanical Retracts

Well today, they worked! I spent 6 hours one day working on them until the battery got down to 4.6 volts. I had removed the factory installed wells and did find binding, as you described, when the wire made and arc and hit the wood on the inner most rib, not accesable from the servo opening. In the factory installed set up, there is no clevis,the push rod connects straight in with a safety keeper. I will look into some grease on the shaft. Will also take another look at the bends to the connectors. Had a mechanical engineer RC bud look at the set up and he said that mechanically one should make the bends as close to the servo arm connector as possible. Just enought to clear the connectors when the arm rotates.
Wish there was a text someplace on these things. i have been in RC since 1968 and have stayed away from retracts because of all the trouble I witnessed. This time I needed a war bird for our fly in and had to have them. May be my last retracts! BTW this Hanger 9 P51 with an OS .91 Surpass II is a beautiful flying machine.
Thanks very much for the advice.
Old 09-02-2002, 02:52 AM
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Default Mechanical Retracts

Well,
Most mecanical retracts don't give you so much hastle
But the new cheapy retracts that come with some arf kits can be troublesome!!!

If you thought that was bad try tuning the retracts on a Global Corsair. Man those have the worse design I'd ever seen.

Don't give up on the warbirds just because you got a funky set-up with this one.

Sounds like your on your way to smoothing it out
Old 09-02-2002, 03:36 AM
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Default Mechanical Retracts

This was a first time, so it has been a real learning experience. The struts are larger than 5/32, but less than 3/16 and a tad over 4 mm. The could be larger and several on the net have changed them. They also were floppy when down becase of loose lock-up I guess. I did figure a way, based on what another person had done, to take up the slack with chrome sticky paper. It has been discourageing, but they did work today. Thank goodness we have a 600 foot asphalt runway. I would hate to try these on grass!
Old 09-02-2002, 05:02 AM
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Default Mechanical Retracts

I went through some similar problems with very sheap mechanical retracts on my WM P-51 GS. Decided to not take a chance with the bird and replaced them with spring airs and robarts struts. Best modification I think I could have made. Warbirds aren't the only thing in RC but man they sure look good flying!
Old 09-11-2002, 05:43 PM
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Default Mech retracts

I have made the long arduous journey through the mechanical world and have had nothing but trouble. I fly from a grass field which is most times very smooth. I have used Great Planes, Hobbico, and another that I've forgotten the name of, and had failures with all. I've been told that Dave Brown makes the best mechanical retract. I will try them next. On larger models I insist on Spring Airs. I also now stay away from Hitech servos. 3 out of 4 failed.
Old 09-11-2002, 10:56 PM
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Default Mechanical Retracts

I have been flying RC for many years and these were my first retracts because I watched too many buddies cry or tear out the bottom of the plane. These came with the plane so I used them. Have gotten most of the problems fixed. If I were to build I would go with Robart air systems. I'm told the Spring air tanks are pitiful and the mechanism has too many problems.
Lucky for me, we fly off asphalt.
Thanks for your insights.
Sky blue, and 52.
Old 09-12-2002, 04:57 AM
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Default Mechanical Retracts

The good thing about Sping airs is if they loose air pressure they automatically go into the 'gear down' position.

TRP
Old 09-12-2002, 12:38 PM
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Default Mechanical Retracts

Originally posted by TRP
The good thing about Sping airs is if they loose air pressure they automatically go into the 'gear down' position.

TRP
Well lets say this happens::
You flying along happy as a clam and you lose pressure, Gear come down so no problem. you keep flying a while with no worries and Oops "Dead stick"!!
you don't have enough speed to make the runway so you have to ditch in the field, and the grass rips those nice spring-airs right out of your wing.
I've seen this happen!! Even with low pressure the conventional gear may have gone up enough to unlock and fold when the plane touched the grass

I have always used Robart gear (since the situation with Roam-airs) and never had a situation where the gear wouldn't come down.
If your system can't hold pressure overnight you have a problem
Old 09-12-2002, 12:49 PM
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Default Mechanical Retracts

Good reply scale_only_4_me I have always thought the Spring Air feature is overly touted for the reasons you mentiond. I also agree that if your pneumatic retracts do not hold air, you need to fix them.

I am not against Spring Air retracts, they are an excellent product and great people.

Vince

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