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  #21  
Old 07-24-2022, 03:39 PM
slyvprdrvr slyvprdrvr is offline
 
Join Date: Aug 2014
Location: SE AZ, Evelyn Field (AZ26) on the PHX Sectional
Posts: 5
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Ando, Sly here. I have a 4 as well thats undergoing complete refurb! Call me!
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  #22  
Old 07-24-2022, 04:37 PM
scsmith scsmith is offline
 
Join Date: Jan 2008
Location: Ashland, OR
Posts: 3,195
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Some comments on our initial data:

The two test runs were really only a bit over an hour apart. The OAT warmed just 1 degree F from the first test series to the second. And the fuel load was the same for both test series.

The resolution of the GPS groundspeed readout on my 396 is 1 kt, so each individual speed point has a resolution (and probably accuracy) of +/- 1/2 kt.

The ability to stabilize conditions over the triangle leg is probably also in the 1/2 kt -- 1 kt range, and in fact I observed cases of 1 kt change in wind speed over the distance of a leg. So these data probably have error bars of about +/- 1 kt in TAS. The only way to improve that is to get more data. I think ForeFlight also outputs GPS speed to 1 kt resolution, so I don't have a tool to improve that. We will do another test run to try to get more statistical sample size when we can, but we wanted to get this out now.

Realistically, I think the cross-over is probably more in the 9500-10k altitude range. But the real key take away here is that down low, (below 7000 ft or so) shedding the extra wetted area of the stock tips does get you something in the ball park of 3 kts. At a cost of 2 kt increase in stall speed.

Another thing I noticed was quicker roll response - not that most of us need that. But if, for example, you like to do vertical rolls, you might get two full rolls instead of 1-1/2 before you poop out.


Quote:
Originally Posted by Bob Kuykendall View Post
Steve Smith and Bob Mills have been very busy at the HP workshop getting the tapered carbon fiber wings onto Bob's Rocket Six in time to turn laps at the NCAR Reno Air Races.

But we've finally made time to do some comparison testing between the HP racing wingtips and the stock W715-1 wingtips. We did Kevin Horten 3-leg GPS triangles at four different altitudes (6000, 7500, 9500, 11500 MSL), first with the HP tips, then with the factory tips two hours later.

As expected, we found a solid 3-knot improvement at 6000 feet, and the data graph points to more at lower altitudes. The crossover altitude appears to be right around 11,000 MSL.



We also tested the stall speed, and found that it was only about 2 knots IAS faster with the short tips.
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RV-8 N825RV
IO-360 A1A
WW 200RV
"The Magic Carpet" Flying since Sept. 2009
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LS6-15/18W sailplane SOLD
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  #23  
Old 08-06-2022, 11:14 PM
Esmokeshop Esmokeshop is offline
 
Join Date: Oct 2021
Location: Ft worth
Posts: 9
Default Just put mine on

this was an easy up grade the stubby look is big winner with the ladys faster would be a bonus as well. took very little work to smooth .. the light lens where the most troubling part not scratching the lens which i did. id like to thank the gentleman at HP who got them to me fast and followed up with good advice and the folks at fly led helped me get the lights i screwed up fixed will post pics when i figure out how tommorw

Last edited by Esmokeshop : 08-06-2022 at 11:17 PM.
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  #24  
Old 08-06-2022, 11:15 PM
Esmokeshop Esmokeshop is offline
 
Join Date: Oct 2021
Location: Ft worth
Posts: 9
Default Just put mine on

this was an easy up grade the stubby look is big winner with the ladys faster would be a bonus as well. took very little work to smooth .. the light lens where the most troubling part not scratching the lens which i did. id like to thank the gentleman at HP who got them to me fast and followed up with good advice and the folks at fly led helped me get the lights i screwed up fixed will post pics when i figure out how tommorw
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  #25  
Old 08-07-2022, 08:57 AM
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Snowflake Snowflake is offline
 
Join Date: Oct 2009
Location: Sidney, BC, Canada
Posts: 4,331
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How do these tips affect the stall speed? I'd expect it to come up, but I don't see any mention of the new stall speed here.
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1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
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  #26  
Old 08-07-2022, 09:20 AM
Tom Martin Tom Martin is offline
 
Join Date: Jan 2005
Location: Ontario, Canada
Posts: 1,610
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Another way to compare wing tips is to fly with different tips on each wing. Yaw will clearly show any speed differences. I did this on my EVO after making some nice wing tips based on a modified 337 tip.
I had taken a paper airfoil shape of the last wing rib and compared it to many planes at Sun and fun until I found that the 337 was close.
Many hours of building modified 337 tips to find that there was a lot more drag then the stock metal EVO tips
I did not check at altitude where the 337 tip may have shown an advantage
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CPL & IFR rated
EVO F1 Rocket 1000 hours,
2010 SARL Rocket 100 race, average speed of 238.6 knots/274.6mph
RV4, RV7, RV10, two HRIIs and five F1 Rockets
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  #27  
Old 08-07-2022, 09:34 AM
Tom Martin Tom Martin is offline
 
Join Date: Jan 2005
Location: Ontario, Canada
Posts: 1,610
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I did note that there was a difference in stall speed with the longer tips, a knot or two lower with the flat tips.
Also, try using metal tape to close all lightening holes on outer and inner wing ribs. The wing can act like an air pump and sealing these holes seemed to help with speed improvements. I did not try this, but taping holes on one wing only would demonstrate yaw effect if there was a difference
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Tom Martin RV1 pilot 4.6hours!
CPL & IFR rated
EVO F1 Rocket 1000 hours,
2010 SARL Rocket 100 race, average speed of 238.6 knots/274.6mph
RV4, RV7, RV10, two HRIIs and five F1 Rockets
RV14 Tail dragger

Fairlea Field
St.Thomas, Ontario Canada, CYQS
fairleafield@gmail.com
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  #28  
Old 08-07-2022, 10:25 AM
RV8JD RV8JD is offline
 
Join Date: Jan 2005
Posts: 540
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Quote:
Originally Posted by Snowflake View Post
How do these tips affect the stall speed? I'd expect it to come up, but I don't see any mention of the new stall speed here.
Quote:
Originally Posted by Bob Kuykendall View Post

We also tested the stall speed, and found that it was only about 2 knots IAS faster with the short tips.
Quote:
Originally Posted by scsmith View Post

At a cost of 2 kt increase in stall speed.
(And extra words.)
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Last edited by RV8JD : 08-07-2022 at 10:30 AM.
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