Q-40 Racing Discuss AMA 422 and any other variants of Quarter 40 racing

Hard landing

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Old 05-30-2010, 05:09 PM
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ecoliburger
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Default Hard landing

Any of you guys ever had servo break from a hard landing? maidened this thing today, second flight I notice the switch is loose. Take it apart at home and find this: Servo mount busted and switch mount broke off as well. Bounced the landing but I didnt think it was that hard, only tweaked one gear a little no wing damage. Doesnt seem to be vibrating very bad? Any ideas?
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Old 05-30-2010, 06:01 PM
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Default RE: Hard landing

Old rotting plastic Maybe both had a crack before you installed them and you didn't notice. The only thing I can imagine might do that is if the servo is bottoming out against the fuselage. But I even doubt that.

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Old 05-30-2010, 06:29 PM
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Default RE: Hard landing

Never seen that before in my life!

Brand new servo? Maybe you torqued it down too much and cracked it straight across....
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Old 05-31-2010, 08:51 AM
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Default RE: Hard landing

It was an older servo, didnt tighten it too much but maybe it was cracked.
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Old 06-04-2010, 07:32 PM
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Default RE: Hard landing

Could be that the servo was mounted in a way that the front and rear mounting blocks could flex in different directions since they aren't tied together...the resulting flex is what broke the servo. Most Q40 racers use an 1/8" ply tray to mount all three servos in the fuse as well as the switch. One tray gives a much larger glue area to the fuse and is stiffer.
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Old 06-04-2010, 09:29 PM
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Default RE: Hard landing

So the plot thickens, this makes no sense to me. I've been flying over 20yrs and never seen anything like this happen. So I got to take a closer look tonight and found that all of the servos are broken in a similar fashion and the receiver is all cracked and not working as well. Apparently I hit hard enough to crack everything inside the fuse but not damage the wing??? Any ideas?

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Old 06-04-2010, 11:08 PM
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Default RE: Hard landing

Good chance it's a hard hit and like Gary says you don't have a tray. You are mounting each end of the servo independently to the fuselage so that the servo housing is bearing the brunt of the impact flex in the fuselage rather than a servo tray. Also it looks like you have mounted the receiver to the fuse with Velcro without a thin piece of foam in there. That could have made a hard life for the receiver. I normally use two layers of Velcro with a thin sheet of foam between them.

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Old 06-04-2010, 11:10 PM
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Default RE: Hard landing

I stand by my thought that the way you have the servos mounted, with seperate mounting blocks for the front and back of the servos, allowed enough flex that it snapped the mounting lugs. As you said it "only tweaked one gear a little no wing damage". The plane very well may have hit in such a way that it twisted the fuse but didn't really put much load on the wing. It wouldn't take much twist to put enough force on the servos to snap the lugs. Personally I'd completely change the radio install to one single tray to mount all three servos and the switch.
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Old 06-05-2010, 11:29 AM
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Default RE: Hard landing

Thanks for the suggestions.
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