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All Forums >> RC Airplanes >> Pylon Universe - RC Pylon Racing >> Q-500 Racing >> Q500 Moments and CG
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Q500 Moments and CG - 1/10/2006 7:52:26 PM   
wkevinm


 

Posts: 141
Joined: 9/17/2004
From: Sherwood Park, AB, CANADA
Status: offline 		Hi

I am making a quickee from scratch and would like opinions on the following moments:

Fuselage
Firewall to Wing LE 4"
Firewall to end of tail - 34 3/8"
Firewall to hingeline on V tail - 32 5/8"
widepoint of fuselage - 12 3/4"
High point of fuse / wing - 8 3/8"

Wing
Wing chord - 9.63"
Span = 52"
Airfoil - NACA 66-012

Engine - Nelson Q40, back plate mount

What is the CG range for a 66-012 airfoil, my guess is 3 1/2 (36%) to 4"(41%) from LE but an earlier post suggests 2.75 - 3"?

Any comments would help, I will be racing in the CPPRA (Canadian Prairie Pylon Racing Association) rules are slightly different than the AMA (wing thick, wide and high points).

Thanks for your support,
Kevin Moorehouse
       Post #: 1

RE: Q500 Moments and CG - 1/10/2006 8:02:16 PM   
diggs_74



Posts: 1281
Joined: 1/20/2004
From: Emerald, WI, USA
Status: offline 		With that airfoil I would say 3" would be the max I would go... Things get a little jumpy much past that. The firewall to leading edge might be a little long unless you are putting your servos behind the wing. I'm sure some guys with more experience than I have will chime in here shortly.


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Lee LaValley
NMPRA# 33w

(in reply to wkevinm)
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RE: Q500 Moments and CG - 1/10/2006 8:28:35 PM   
DMyer


 

Posts: 487
Joined: 10/16/2002
From: Potomac, MD, USA
Status: offline 		I would shoot for 2 7/8" for the CG.... that will require about 3/16" up elevator for a proper turn. I would not go beyond 3 even though I have personally flown as much as 3.25 it is far too pitch sensitive. The Goldilocks spot is IMO is 2 7/8".


dan

(in reply to diggs_74)
       Post #: 3

RE: Q500 Moments and CG - 1/10/2006 9:52:06 PM   
Ed Smith


 

Posts: 2837
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: offline 		A word of caution here. A wing chord of 9.63 and a span of 52 gives a wing area of 500.76 sq". If you put a rad on your wing tips or even worse have an elliptical shape the wing will be undersize and illegal. I would suggest a chord of 9.75 min.

Ed S

(in reply to wkevinm)
       Post #: 4

RE: Q500 Moments and CG - 1/10/2006 10:18:53 PM   
diggs_74



Posts: 1281
Joined: 1/20/2004
From: Emerald, WI, USA
Status: offline 		Ed, I always thought the span measurement was a projected distance in a straight line not including dihedral... I didn't think wing tip shape was taken into account...Not trying to be a smart a$$ just wondering... If this is the case I have had a couple wings with the 9.3" chord that was constant for 47.5" and wingtips that angled out from the LE to 2.25" at the TE...I guess was cheating..

< Message edited by diggs_74 -- 1/10/2006 10:21:20 PM >


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Lee LaValley
NMPRA# 33w

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RE: Q500 Moments and CG - 1/10/2006 10:43:02 PM   
splatt



Posts: 651
Joined: 1/30/2002
From: splattsville, MN,
Status: offline 		I knew it , I just knew it....


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RE: Q500 Moments and CG - 1/10/2006 11:27:35 PM   
garys


 

Posts: 756
Joined: 1/31/2002
From: San Diego, CA, USA
Status: offline 		Lee, you are correct in how the span is measured, but incorrect about the tips not being taken into account...any Q500 wing with a 9.3" chord is illegal....
GS

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GS

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RE: Q500 Moments and CG - 1/10/2006 11:51:45 PM   
js3



Posts: 1142
Joined: 1/30/2002
From: Arvada, CO, USA
Status: offline 		Kevin,

Make the wide point of the fuselage just before the trailing edge of the wing. This is a way to fake a wing fillet and as you probably know, fillets are against the rules.

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John
I feel a lot more like I do now than I did earlier!

(in reply to garys)
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RE: Q500 Moments and CG - 1/11/2006 3:21:43 AM   
Truckracer


 

Posts: 567
Joined: 4/3/2004
From: Des Moines, IA, USA
Status: offline 		Lee,

OK, the next time you beat me, my tape measure will be in hand!!

Roger S.

(in reply to diggs_74)
       Post #: 9

RE: Q500 Moments and CG - 1/11/2006 3:56:46 AM   
diggs_74



Posts: 1281
Joined: 1/20/2004
From: Emerald, WI, USA
Status: offline 		Don't worry too much Roger, Jesse, other NCPL racers... That wing and fuse are long gone... As a matter of fact, that wing lasted all of one lap.. However, it was the most spectacular mid-air I have ever seen and it was a pass for the lead around #2.. Took a Viper right in the middle of the wing right between the front wing bolts... A perfect hole the size of a spinner nut.... The only surviving part was the engine, the rest was junk.

The only reason I asked about the tips is that I didn't see it mentioned in the rules with regards to the wing area(I'm not implying it isn't there just that I didn't see it) .. If the tip area is to be included then who does the trig to figure out the area that is missing on a radius shaped tip??


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Lee LaValley
NMPRA# 33w

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RE: Q500 Moments and CG - 1/11/2006 5:12:40 AM   
HighPlains


 

Posts: 2668
Joined: 3/2/2003
From: Over da rainbow, KS, USA
Status: offline 		The math is simple for just a rounded or parabolic shape. Or we can just count squares and get close.

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RE: Q500 Moments and CG - 1/11/2006 12:28:01 PM   
Ed Smith


 

Posts: 2837
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: offline
quote:

The only reason I asked about the tips is that I didn't see it mentioned in the rules with regards to the wing area(I'm not implying it isn't there just that I didn't see it) ..


There is no mention of wingtips in the rule. The rule states just the minimum projected wing area. It obviously means the whole wing.

Ed S

(in reply to diggs_74)
       Post #: 12

RE: Q500 Moments and CG - 1/11/2006 2:07:24 PM   
diggs_74



Posts: 1281
Joined: 1/20/2004
From: Emerald, WI, USA
Status: offline 		If it was that obvious I wouldn't have raced an illegal wing ... Oh well, I guess a guy learns something new every day.


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Lee LaValley
NMPRA# 33w

(in reply to Ed Smith)
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RE: Q500 Moments and CG - 1/11/2006 2:30:32 PM   
HighPlains


 

Posts: 2668
Joined: 3/2/2003
From: Over da rainbow, KS, USA
Status: offline 		Nobody really looks too hard..........unless you win.

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(in reply to diggs_74)
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RE: Q500 Moments and CG - 1/11/2006 3:07:14 PM   
splatt



Posts: 651
Joined: 1/30/2002
From: splattsville, MN,
Status: offline 		Buy me a beer, I might forgive you, make that 2


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RE: Q500 Moments and CG - 1/11/2006 3:44:33 PM