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Old Jul 18, 2011, 11:08 PM
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Quote:
Originally Posted by pavcon View Post
the cheater hole cover
Are you using the full cover for the cheater hole? or the one with the holes?

If its the one that fully covers it, thats probably the biggest reason it does not balloon.
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Old Jul 19, 2011, 02:50 AM
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no. The one with small holes.
You need somehing there to block the airflow from going in the cheater hole and comming out from the cheater hole when the fan is still.
Thats one of the reasons the plane reacts like that. When air flows in the cheaterhole and doesnt get out from the exhaust it sucks the rear end of the plane down causing the balooning. You should also check that point i posted with the elevator insidence too
Old Jul 19, 2011, 06:26 AM
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When the fan is still, how can the the air flow into the cheater and suck the tail down? That makes no sense whatsoever. I'm pretty sure that the ballooning is a simple cg issue, probably caused because the thrust line isn't quite true.......so under power it holds the nose down, but when you throttle back, the too-aft cg causes the 'ballooning' as you call it. Secondly, you should be landing with power anyway, not dead stick. It's a jet.
The elevator does take some force to sit true, but it cannot cause the ballooning as it would effect power on and off equally.
If it only happens when you throttle back it has to be a thrust line / cg combination issue.
Old Jul 19, 2011, 06:54 AM
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its not cg issue man. For sure. I asked a pilot about this. He explained everything. With my previous panther cg was at 60mm still, ti was ballooning like it was disabling gravity. If the fan is moving and the air is escaping through the exhaust nozzle then there is no problem. If its not and a significan amount of air just move along the cheater hole and escapes under the plane it causes that sucking effect. Im posting from my mob now. When i get home i will take a photo and draw some lines explaining everything.
Old Jul 19, 2011, 06:58 AM
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btw if your read way baxk in the thread you will realised that we checked each and every aspect of the prob. It was either insidence, cg or the cheater hole. The cg was definetely not one of the since ive flown mine super nose heavy and when i was disabling the throttle the balloning was there
Old Jul 19, 2011, 07:40 AM
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I'm finishing up another 4S Panther I'll try it with and without the cover and let you know what I find out.
Mike
Old Jul 19, 2011, 08:05 AM
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nice mike...
Dont forget to pay attention on elevator glueing.
Old Jul 19, 2011, 08:14 AM
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It was taken care of when I built it over a year ago. I set it aside till the other day when I was installing some new electric retracts. I never had the ballooning issue ( without the cover) with my first one either just issues with the junk first run retracts. I bungee launched that one.
Mike
Old Jul 19, 2011, 08:35 AM
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good.,.. can't wait for the results
Old Jul 19, 2011, 08:36 AM
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Just need a break from this 100+ heat and I'll be good to go.
Mike
Old Jul 19, 2011, 09:16 AM
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If the fan isn't moving, air can still escape out the exhaust. Even if it didn't, and the exhaustive blocked, air coming in the intakes and escaping out the cheater wouldn't cause a sucking, it would be a blowing, and cause a pitch down, not up. I'm not saying the cover definitely isn't the problem, just that the explanation defies the laws of physics.
Old Jul 19, 2011, 11:25 AM
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smorris .. it would cause sucking.. I thought that it would cause blowing too.. but that's not the case.. I'm sure about this.. google it I was so dissappointed from the first panther I was ready to call air crash investigation from national geografic
I made so much research about this.. I'm not talking with maybes or ifs.. believe me.. Ive done my homework on this.. that's why my panther now flies flowlessly.
and when I made the maiden this second panther and it was balooning I was sure it was a matter of cg and I was confident it was going to be ok with just moving the cg point forward.. and it did. I was feeling from the plane reactions that it was tailheavy.
Old Jul 19, 2011, 11:33 AM
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I don't need to. It's simple physics. Air going in the front and coming out the bottom is a change in momentum downward. As every action has an equal an opposite reaction, this pushes the back of the plane up. It's why rockets, with all the gases coming out the bottom, go up, not down.
Anyway, like I mentioned earlier, why wouldn't the air just come out the tail????
I'm looking at a lander panther now, and I still think its a cg / thrustline issue because it only happens when you throttle off. It's such a short coupled plane, its incredibly pitch sensitive.
Either way, as long as its not ballooning anymore, its all good. But please, stop landing deadstick. :P
Old Jul 19, 2011, 12:08 PM
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explanation


Quote:
Originally Posted by SMorrisRC View Post
If the fan isn't moving, air can still escape out the exhaust. Even if it didn't, and the exhaustive blocked, air coming in the intakes and escaping out the cheater wouldn't cause a sucking, it would be a blowing, and cause a pitch down, not up. I'm not saying the cover definitely isn't the problem, just that the explanation defies the laws of physics.
It was explained to me that the uncovered cheater hole causes a low pressure area that tends to pitch the nose down under power. So to fly level under power you would need to trim in some up trim. The problem arises that when you reduce the power, the low pressure is reduced and now your aircraft is not trimmed for level flight and will balloon up. Some pilots have had success with mixing in some down elevator at low throttle settings to compensate. It is not too different from a propeller driven aircraft that has too much down thrust built into the firewall. Reducing power makes the aircraft want to climb due to excessive downthrust being cancelled out. My two panthers have the swiss cheese covers and both have some ballooning. My Cougar is completely covered and so far I have had no ballooning with it.
Old Jul 19, 2011, 12:10 PM
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ok morris you know better than a pilot... What can i say


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