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Old Dec 08, 2012, 06:33 AM
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Berkie's Avatar
Australia, VIC, Rosebud
Joined Feb 2007
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Foamies that won't recover from steep dives

Hi All

It has happened again! No recovery from a steep dive.
I have had this happen once in an EZ* and 3 times now in EZ glider Pro
This time I wanted to see how she would stabilise fro a nose down attitude so I let go of the sticks, but the dive steepened quickly, I applied full up, but no result.
She went in vertical

After the crash I found the ESC & motor to be very hot which was probably due to a full throttle climb. Even though the ESC may have failed control should have been OK because it has a separate Rx battery, although I did try throttle just before she hit and I am not sure, but I don't think there was a response. All 4 servos were still working after the crash (didn't test motor)

A thing I thought strange though, was as I got close to the wreck (say 10 metres) the FrSky Tx beeped telling me there is loss of signal. Funny, because with the aircraft on the ground it should have beeped 50 metres away then stopped when I got to 10 metres.

Is this crash due to the higher load in a dive that the control system in these foamies just won't cut it? E.g. the control wire is too long and cannot exert enough force?
I have not heard of EZGPs needing the elevator servo mounted in the tail, but it looks like that's what I will have to do
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Old Dec 09, 2012, 10:55 AM
The Prez....... again
kenh3497's Avatar
United States, IA, Rockwell
Joined Jul 2011
4,288 Posts
Did you reduce the throttle in the dive? I can see blow back on the elevator in a full power dive.
\
Ken
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Old Dec 10, 2012, 12:39 AM
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Berkie's Avatar
Australia, VIC, Rosebud
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Quote:
Originally Posted by kenh3497 View Post
Did you reduce the throttle in the dive? I can see blow back on the elevator in a full power dive.
\
Ken
Yes Ken the power was off

Kev
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Old Dec 10, 2012, 02:01 PM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
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As Ken mentioned, blow back.

With the usual, 'push for up' push rod set up, i.e. elevator horn on the underside, then a check with a little finger pressure on the elevator while operating the servo is worthwhile.

If the push rod is flexing or bending, then something need changing before any high speed flying.
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Old Dec 11, 2012, 05:57 AM
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Berkie's Avatar
Australia, VIC, Rosebud
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Quote:
Originally Posted by eflightray View Post
As Ken mentioned, blow back.

With the usual, 'push for up' push rod set up, i.e. elevator horn on the underside, then a check with a little finger pressure on the elevator while operating the servo is worthwhile.

If the push rod is flexing or bending, then something need changing before any high speed flying.
Thanks eflight
I'm going for elevator servo at the tail now for all long fuz planes.

I think that is the best insurance

Kev
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Old Dec 11, 2012, 08:12 AM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
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Quote:
Originally Posted by Berkie View Post
Thanks eflight
I'm going for elevator servo at the tail now for all long fuz planes.

I think that is the best insurance

Kev
Yes, but.

Watch the CG. Adding even 9 grams towards the tail can mean quite a chunk of lead at the front to compensate. It's the lever problem with shortish noses.

9 grams 12" from the CG, needs 36 grams 3" the other side to maintain the balance.

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Old Dec 11, 2012, 07:41 PM
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Quote:
Originally Posted by eflightray View Post
Yes, but.

Watch the CG. Adding even 9 grams towards the tail can mean quite a chunk of lead at the front to compensate. It's the lever problem with shortish noses.

9 grams 12" from the CG, needs 36 grams 3" the other side to maintain the balance.

Thanks eflight.

I am always careful on CG which I would have checked but, I wasn't taking into account the weight penalty. So now that you have given me the heads up I think I'll look for a lighter servo than the 12g I have in there now.

Lighter will mean less torque, but it should not need a lot in that position

Kev
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Old Dec 11, 2012, 07:54 PM
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What do you think guys- will this fit the bill?

http://www.hobbyking.com/hobbyking/s...2kg_10sec.html

Kev
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