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Cherokee Six w/ Black leading edges

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Cherokee Six w/ Black leading edges

Old 16th Jan 2014, 21:12
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Join Date: Jul 2012
Location: Mozambique
Age: 30
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Cherokee Six w/ Black leading edges

Hi,
I am flying a Cherokee six in Mozambique, you know how hot it gets here. We bought a Cherokee six with black painted leading edges. For some reason, I am not sure if this is THE factor, but this Cherokee six has less performance than the other ones we have. I am not sure if the black painted leading edges might contribute to the performance degradation we have been noticing. When we are on the ground and the sun is hitting the wing, you simply cannot hold your hand more than 5 seconds on the black stripe, itís burning hot. Do you think it might influence the wings aerodynamic flow?

Regards,
JM
Jorge Martins is offline  
Old 16th Jan 2014, 21:50
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Join Date: Feb 2009
Location: dans un cercle dont le centre est eveywhere et circumfernce n'est nulle part
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I'd look at differences in engine hours, wear and tear, propeller, governors, rigging and the like before I went to work on black leading edges which probably do more to protect from stone strikes than degrade performance in the heat. My aeroplane is dark blue but it goes faster, climbs better and uses the same fuel than lighter colored versions I've seen. The only difference I can see is I have a TAS ASI and OAT. The others an IAS ASI. I'll leave it to the 'real experts' on PPRuNe to guide you on influence on aerodynamics.
Frank Arouet is offline  
Old 16th Jan 2014, 22:42
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Join Date: Nov 2012
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Diiferential Expansion

It may not affect performance but I will bet money that it stretches the skins at different rates in the wing. I had an ultralight that I did a repair on once that had dark blue leading edges and thin wing skins and you could hear the skins moving in the heat. White is the colour I like the most on cars and aeroplanes.
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Old 16th Jan 2014, 23:57
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Join Date: Feb 2006
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Have a look at wing rigging. There can be quite a difference between flap & aileron settings between Pipers. The maintenance manual describes a rigging jig. But if you get 2 or 3 side by side and put a 1m piece of wood along the bottom of the wing touching the flap / aileron trailing edge then look at the gap between the wood and the rear part of the actual wing, you'll very quickly get an idea if one is different. There should be about 5mm gap. The better take-off cherokees might have more.
Old Akro is offline  
Old 17th Jan 2014, 00:26
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Join Date: Feb 2006
Location: Melbourne
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Actually, the easier way is to look at the distance between the flap trailing edge and the bottom of the fuselage (some LAME's count exposed threads on the adjustment turnbuckle) then look at the aileron trailing edges compared with the flaps.

Another common differences are incorrect calibration of the tacho (ie you are doing more or less RPM than you think).

Cruise speed on the Cherokee 6 varies a bit depending on CofG position. Does one aircraft carry more junk? Or radio's down the back?
Old Akro is offline  
Old 17th Jan 2014, 02:33
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Join Date: Dec 2009
Location: Australia
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Forgive me for asking the obvious question, but do they all have the same engine? Piper did produce the Cherokee Six in 260hp and 300hp versions.
Look Mum - no hands is online now  
Old 17th Jan 2014, 06:54
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Join Date: Sep 2007
Location: Brisbane, Qld
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You'll need to paint the leading edges Red...cause everyone knows that Red goes faster!!!
Ixixly is offline  
Old 18th Jan 2014, 10:38
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Join Date: Apr 2005
Location: OZ
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As others have said it may end up being you have one aircraft that is a dog and one that is not.

However I would check the rigging and start at the cable tension on the ailerons.
Sometimes when this has dropped tension they look ok on the ground but in flight the airflow gives in upward deflection. Once tensioned correctly they are flush and match airfoil of the wing.

If you have the upward deflection you may be producing less lift on that section of the wing, correct tension also helps with the old lullaby wing roll on autopilots.
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