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Old Sep 01, 2012, 03:04 PM
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United States, FL, Hollywood
Joined Aug 2010
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I repaired the front gear door hinge with epoxy, then layered on another coat to reinforce the break. Hope it works. Looks good.
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Old Sep 01, 2012, 10:53 PM
John
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United States, NV, Las Vegas
Joined Mar 2011
436 Posts
Hey guys,
Sorry I haven't responded to anyone since I had my misfortune on thursday. Honestly, I've been so irritated with myself for making such a rookie mistake I didn't want to talk to anyone... I was actually just going to count my losses and ditch this airframe and buy another one from bananahobby or hobbyking... but today I was just sitting down depressed in my livingroom. then i just said, screw this I'm gonna fix that dang plane.... so i grabbed all my broken pieces from the trunk of my car and just started trying to put this mangled jigsaw puzzle together... little by little she started taking shape again! she's finished for tonight... tomorrow I just need to sand down the foam putty and then I am going to paint the nose cone... here's my progress so far.

Thanks for everyone's encouraging words and for encouragin me to rebuild this plane...
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Old Sep 01, 2012, 11:28 PM
Should've, Would've, Could've
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United States, CA
Joined Dec 2010
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Looking good. Sometimes you just gotta sit back wait a few days and assess the damage. Makes putting the pieces back together easier and willing.
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Old Sep 02, 2012, 12:35 AM
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Canada, AB, Calgary
Joined Oct 2010
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Cg

Anyone feels CG on this plane is too high? Amount of counter-aileron I have to give to get into a leveled flight after a sharp turn concerns me. The plane feels a bit like bicycle - it tries to bank left or right (especially at WOT) all the time. I'm using 5000mAh battery and stock cg.
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Old Sep 02, 2012, 04:21 AM
Life begins at transition
Australia, VIC, Sale
Joined May 2007
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The vertical position of the CoG doesn't affect lateral stability (roll). Lift is always acting through the same point, regardless of the angle of bank, and therefore has no restorative moment.

Dihedral is what you're after. Not scale, but can be easily added to the aircraft. A degree or two should make the plane noticeably more stable.
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Old Sep 02, 2012, 08:06 AM
Flying Hazard
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Spain
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Well, it actually does.
Dihedral is more important but a high CoG will also make an airplane more Roll-unstable.
Specially a jet because of short wings and low inertia.
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Old Sep 02, 2012, 08:20 AM
Life begins at transition
Australia, VIC, Sale
Joined May 2007
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How does a high CoG affect lateral stability? I can't see a way it can generate a moment?
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Old Sep 02, 2012, 08:21 AM
You are a "go" for reentry
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Sockrat; try a roll with the gear down and see if it differs. It is slightly but no enough to impede judging by the displayed roll rates.

I assume you have the ailerons Y'd so that it wouldn't be dif or servo arm isn't positioned to induce uneven throws top or bottom.

Beyond that the only other route is change to functioning tailerons for a greater roll moment. TV in roll helps when thrust is engaged but there are a lot of times that you'd be off the throttle so....

Oh and are your Ail servos working fine?
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Old Sep 02, 2012, 10:58 AM
Should've, Would've, Could've
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United States, CA
Joined Dec 2010
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Sitting on 22's

An Su aint an Su without its signature green wheels Pitot Tubes next for the Final detail!
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Old Sep 02, 2012, 12:24 PM
You are a "go" for reentry
Maxthrottle's Avatar
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Quote:
Originally Posted by Odysis View Post
How does a high CoG affect lateral stability? I can't see a way it can generate a moment?
Depends on your meaning but short moment vs long moment; skaters spin rate arm in vs out.
If I put a weight on a pole and stuck it on top, it would balance at level, but as you roll, the ail deflection force is less as the roll starts as the weight naturally speeds the roll to invert, and greater to pull that weight back around top.

Dihed moves the CG to a lower position rel to AC and as SU said it forces aerodynamic stability like that of a trainer. So with velocity you get an induced effect that's generally not desired for a 3D model.

The battery sits above the EDFs, the landing gear and the rest of the fuse so it is expected to some degree. The tailerons position gives it a better moment in roll but induces the offset corkscrew effect being aft and lower.
It also varies with neutral to nose heavy with the shift of the battery.
All small effects but creating what Sockrat may be observing.


V8 love the green wheels.
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Old Sep 02, 2012, 02:21 PM
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Canada, AB, Calgary
Joined Oct 2010
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All servos working fine, throws up to manual. Might be the altitude that causes it - 1200m (4000ft)?
If I compare SU 34 and 35 - the first one has battery at the very bottom, this one at roof. And 34 is way more stable in turns. On the other hand EF has a high battery too but no such tendency. In MIG-29 they placed one battery low in nose for that purpose I think (don't believe guy didn't have an idea to place it like in 35 - there's a perfect spot behind retracts there)
High CG makes plane non-flyable - I once mounted FPV camera with battery and transmitter on Supercub above the cabin (right at CG but like 15cm above). The plane was constantly trying to flip upside-down even in leveled flight.
To summarize what differs SU-35 is If I make a turn with wings 45 degrees to horizon and then put ailerons to neutral: trainer will level, most edf's I have will continue turn and maybe slightly level up, SU-35 will either stay in turn or stall by making wings 90 degrees. So, pilot has to do a little of counter-aileron to keep it in turn and like 70% opposite to level.
Anyone has the same feeling?
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Old Sep 02, 2012, 04:01 PM
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I weighed my camera mount and cam and it was 2.5 oz, one of the big clips weighed 1 oz and I used it as a counterbalance on the other wing. I moved my 5000 all the way forward to keep cg the same and used high rates. It flew like crap! The weight on the wingtips made easier to over control. I was so busy trying to smooth it out that I didn't think to try low rates.
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Old Sep 02, 2012, 06:06 PM
Flying Hazard
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Quote:
Originally Posted by Sockrat View Post
To summarize what differs SU-35 is If I make a turn with wings 45 degrees to horizon and then put ailerons to neutral: trainer will level, most edf's I have will continue turn and maybe slightly level up, SU-35 will either stay in turn or stall by making wings 90 degrees. So, pilot has to do a little of counter-aileron to keep it in turn and like 70% opposite to level.
Anyone has the same feeling?
I actually don't have to.

You could be also experiencing the effects of a very NOSE HEAVY plane effect. If you have your CG too much forward for a stable setup, on th turns, the airplane will tend to bank deeper because of the moment created by the pair of forces weight vs lift. (Think of CG being ahead of center of pressure).

Cheers!
Jandro.
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Old Sep 02, 2012, 06:10 PM
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I thought the flat spin was better on low rates. I'll have to try an inverted flat spin on low rates.

Flanker2 001 (5 min 6 sec)
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Old Sep 02, 2012, 06:58 PM
John
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United States, NV, Las Vegas
Joined Mar 2011
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Quote:
Originally Posted by merlinfan View Post
I thought the flat spin was better on low rates. I'll have to try an inverted flat spin on low rates.

http://m.youtube.com/watch?v=2C-YcScLV8I]
Very Nice Flight... I especially liked the landing, very soft very gentle!
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