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RE: CoroCub - a little bigger one. - 11/5/2007 9:56 AM   
RysiuM



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Status: offline 		We flew today again - it is so much fun. We took some measurments and I am very confused. There was a little crosswing but we still decided to take two speed measurments (both directions). Measuring the sound of the engine I calculated 7620 rpm (on MA 16x8 Classic). Now the weired thing is, that when I put the data into doppler formula I got the ground speed 70 mph. But at that rpm 8 inch pich prop will move no more than 58mph. What the heck? Maybe the MA prop does have more than 8 inch pich?

The frequency were: In = 140Hz, Center=127Hz, Out = 117Hz. It was low fast pass.

I measured the sound wave from that video clip using all available tools. When the airplane was exactly in front of us the recording indicated 7620 rpm (127Hz).

Anyway, I flew a little later with APC 16.5x5. I did not read the rpm, but it was noticable faster. The plane flew better too. I think I will leave this APC on it.

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RE: CoroCub - a little bigger one. - 11/6/2007 1:15 PM   
MrGreenSpeed



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Status: offline 		This might help.
Here is a link to a Doppler Speed program thread at spadworld.net
http://spadworld.net/forum/viewtopic.php?t=14713
Jeff

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RE: CoroCub - a little bigger one. - 11/6/2007 4:13 PM   
ChrisSpad



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Status: offline 		the prop pitch doesn't take into account the lift produced by the prop itself. Its very possible to get a much higher speed than the prop pitch at a specified rpm, provided the airframe's nice and slippery in the air.

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RE: CoroCub - a little bigger one. - 11/6/2007 9:22 PM   
RysiuM



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quote:

ORIGINAL: ChrisSpad
Its very possible to get a much higher speed than the prop pitch at a specified rpm, provided the airframe's nice and slippery in the air.


This might explain, however CoroCub for sure is not "nice and slippery"


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RE: CoroCub - a little bigger one. - 11/7/2007 12:14 AM   
ChrisSpad



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Status: offline 		its probably more aerodynamic than you'd think - the biggest cause of drag is the wing, and the cub has a very long skinny wing - much like a glider, which has very little drag.

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RE: CoroCub - a little bigger one. - 11/7/2007 3:15 AM   
RysiuM



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Status: offline 		Now it's time to paint it. I will get it like Pipers used as corp dusters after WWII in Poland. See the picture below. The nose is blue, fuselage light grey-silver (I will leave it white), Polish checkboard on the ruder and PLL-LOT text on the fin.

Attachments
Click to see fullsize image.
Click for fullsize 		Click to see fullsize image.
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< Message edited by RysiuM -- 11/7/2007 3:16 AM >

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RE: CoroCub - a little bigger one. - 11/7/2007 4:21 AM   
DLSmith2



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Status: offline 		Looking forward to seeing the finished product!

Keep up the great SPADding!!!

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RE: CoroCub - a little bigger one. - 11/7/2007 4:25 AM   
RysiuM



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quote:

ORIGINAL: DLSmith2
Keep up the great SPADding!!!


So many planes, so little space


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RE: CoroCub - a little bigger one. - 11/23/2008 9:29 PM   
Villa



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Status: offline 		Hi RysiuM
Still flying your CORO Piper Cub? How has it been doing? Did you ever finish painting it?

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RE: CoroCub - a little bigger one. - 11/23/2008 10:04 PM   
RysiuM



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Status: offline 		Unfortunately I have not been flying for last couple months - to busy And the Cub is still the same hape except it received Spectrum receiver (I converted my Futana 8US to Spectrum using 109 dollars deal from Horizon).

But next month I will officially pass the presidency of my club to the new elected president (I mean the MASM President, not USA ) so I hope being a simple member I will have more time for hobby. I have so much backlog in RC.

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All Forums >> RC Airplanes >> S.P.A.D. Aircraft - Coroplast design >> RE: CoroCub - a little bigger one.
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