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My first crash - H-9 Cherokee 40

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Old 02-04-2012, 06:09 AM
  #1
zan79
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Default My first crash - H-9 Cherokee 40

Hello!

Yesterday, one and a half year since I started flying rc models, I finally had the honor of smashing down on of my planes. To be honest, I deserved it.

At my 3rd flight of the day, during a long dive from high altitude, I tried to roll my plane and felt a strange and weak response. I immediately began to straighten up for an emergency landing but the runway was occupied by another plane preparing to take off. At this point I already understood that I am experiencing some kind of rx battery failure and pointed the plane away from the other flyers. Last thing I tried to do was to shut down the engine but it was to late, I completly lost it. I just stood there and watch the plane flying itself right into the ground.

The battery I used was 1800 mah NiMh. It was fully charged at the begining of the day and my voltwatch indicated maximum power prior to this flight. I think that over charging it too many times worned it out.

Luckilythe plane's body survived the crahs but the wing broke right in the middle devided into two halfs.The final result can be seen at the attached photos. I regret that I didn't take a photo of the crash sight...

Being completly rookie at building I need an advice about how to fix the wing.

Any suggestion would be appreciated.

Thanks!
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Old 02-04-2012, 08:15 AM
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Jose Machado
 
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Default RE: My first crash - H-9 Cherokee 40

Easy, insert a beam were the old one was join both wings, and use a lot of 30 minute epoxy, cover with medium fiberglass, about 4 inches wide.
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Old 02-04-2012, 12:57 PM
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Roo Man
 
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Default RE: My first crash - H-9 Cherokee 40


[quote]ORIGINAL: zan79

Hello!


The battery I used was 1800 mah NiMh. It was fully charged at the begining of the day and my voltwatch indicated maximum power prior to this flight. I think that over charging it too many times worned it out.

What do you mean by over charging?

If this is one of the new versions of NIMH it should not be charged over 500 MAH and an auto shut down charger is recomended. They should also not be trickle charged.


Gary
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Old 02-05-2012, 09:48 AM
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Default RE: My first crash - H-9 Cherokee 40

Thank you Jose,

What do you mean by "insert a beam..."? should I drill the broken beams that goes into the wing and replace them? Or just put a new one instead of the one that's missing?

Thanks again.
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Old 02-05-2012, 09:51 AM
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Default RE: My first crash - H-9 Cherokee 40

Hello Gary,

I know all about that now, when it's too late. Should have done my homework at the right time...

Thanks for your reply.
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Old 02-05-2012, 06:06 PM
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Default RE: My first crash - H-9 Cherokee 40

There was a "wing joiner" between the two wing halves. It is placed vertical between the upper and lower spars. You can see where it is broken.

I think what Jose wants you to do is remove the old joiner by what ever means necessary. To do that you will need to cut away some of the sheeting on the wing to gain access to the spar area. Make up a new joiner and glue it in place. Then, some 4 inch wide fiberglass cloth is laid on the wing so two inches is on each wing panel. This is attached with some slow set epoxy. This will give a very strong joint to the wing. In my opinion I would glue the wing halves back together as is and use the fiberglass method to strengthen the joint. I've done this many times and it has never failed except in a crash. Get the opinion of some of your fellow pilots. They are right there and can see first hand the complete extend of the damage. Use their expertise and thank them for it.

Ken
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Old 02-08-2012, 01:18 AM
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Default RE: My first crash - H-9 Cherokee 40

Thank you Ken, for your informative comment.

I might go with your advice.
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Old 02-20-2012, 08:24 AM
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Default RE: My first crash - H-9 Cherokee 40

Although the Cherokee can perform aerobatics, it is NOT designed for a hard or 3D Style maneuver!

From the photos, I see a very clean break on a wing that had minimal strength for Scale type flight and mild aerobatics.

Wing Leading edge, Main spar, and trailing edge dihedral braces, with, fiberglass center section enforcement will make a wing center section very solid as a unit. These braces are made from quality grade Plywood, and extend outward from center at least beyond two rib's, better three, on each side!

This is for plenty/extra strength, your Cherokee will do fine with the above suggested repairs! Good Luck!

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