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Old Feb 01, 2013, 07:03 PM
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New Mexico
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Thanks for the quick response. I may give it a try.

Bruce T.
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Old Feb 02, 2013, 05:21 AM
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Larry Jolly's Avatar
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Nice work Tuan,
Looking forward to seeing you fly your CG that far back. Honestly the stock Aspire stab at 120mm CG will offer identical handling to what I saw in your video. The Aspire is still a great flying glider and very competitive. LJ
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Old Feb 02, 2013, 09:17 AM
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United States, CA, Midway City
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Originally Posted by Larry Jolly View Post
Nice work Tuan,
Looking forward to seeing you fly your CG that far back. Honestly the stock Aspire stab at 120mm CG will offer identical handling to what I saw in your video. The Aspire is still a great flying glider and very competitive. LJ
Hi Larry, hope all is going well for you.
This was only my 5th outing with this plane so I still need more time with it, but absolutely agree that the Aspire is a great flying glider and still very competitive. Hopefully tomorrow I will get out (Downey) to put it on a winch and see what it will do with cg that far back.
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Old Feb 12, 2013, 08:53 AM
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Jyvaskyla, Finland
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Originally Posted by fnnwizard View Post
The stock Xplorer stab rod will slide inside the Aspire stab hollow rod, so I just cut a piece of the hollow rod as wide as the pivot bearing and slid it over the solid rod. I rolled up some 600 paper and gave the hollow rod a few twists with it and the fit is a very tight friction fit.

Besides the obvious need to trim the stab curvature for minimum gap between the V stab, I also needed to trim a bit where the stab can contact the rudder when it's at full deflection. 30 minute job if doing precision work, 10 minutes if not.
I like Aspire much better with Xplorer elevators. I use about 118-119mm CG with Xp elevators. The original elevators are best either with really forward or rearward CG. This loads the elevators positively (or negatively) and helps with the aerodynamic slop created by thick airfoil.

I have never understood why x-tail Aspire has such a thick elevator profile? What were they looking after??
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Old Feb 12, 2013, 09:51 AM
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United States, AZ, Buckeye
Joined Mar 2010
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I think my Aspire's fly great with the stock elevators. I just don't see what I could possibly gain from a different elevator. Even at 72oz my dissed goes up in light lift and will still float out the morning flight. And the spread tow well its just amazing IMHO.

Joe
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Old Feb 12, 2013, 02:38 PM
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Jyvaskyla, Finland
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Originally Posted by J. Wydronek View Post
I think my Aspire's fly great with the stock elevators. I just don't see what I could possibly gain from a different elevator.
It depends totally on what CG you have. I also fly my heavy double carbon model with original elevators but it has a very safe CG, around 116mm. Hence elevators are always loaded (down).
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Old Feb 12, 2013, 03:31 PM
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Tuomo,
I am calling bull here.....You or Tuan please tell concisely what you are trying to tell us . Lots of time on Aspires 120ish CG..Exactly what would putting an Explorer Stab on an Aspire do for me.... Hint I flew one and tested it and could not find any improvement... LJ
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Old Feb 13, 2013, 12:57 AM
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United States, CA, Midway City
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Originally Posted by Larry Jolly View Post
Tuomo,
I am calling bull here.....You or Tuan please tell concisely what you are trying to tell us . Lots of time on Aspires 120ish CG..Exactly what would putting an Explorer Stab on an Aspire do for me.... Hint I flew one and tested it and could not find any improvement... LJ
Hi Larry,
I can give experience and data!
On my ST, when it was balanced at 120 with the stock stabs, I find it seem to always "hunt" in pitch when flown in turbulence. 4-5 weeks ago, it was only my 4th outing with the plane. Mark Child got some time on it in turbulence and he also noted it seem "pitchy".
The reason why I chose to use 120, was according to XFLR, she should be stable at 120.
Anyhow, I did some analysis and the stock Aspire stabs are the same efficiency as the small Xplorer stabs. This is shown on XFLR by the same slope in the CM vs Alpha graphs. Yep, I didn't believe it myself.

Of course, I had to rerun the analysis with the larger Xplorer stabs and sure enough the slope was steeper with the larger stabs.

That tells me that if I were to fly Aspire with its stock stabs at 117, I can throw the Xplorer small stabs on and should get the same static margins.

With the larger Xplorer stabs, the cg can go back an additional 9-10mm compared to the Aspire stabs to offer the same static margins.

This data set lines up perfectly with my analysis of the lg vs sm Xplorer stabs on the 3.8 and 4.0 Xplorers. That is, the larger stabs move the static margins back 10mm. You can clearly see that in the graphs.

Again, I didn't believe it myself, but my plane flies oh so nice at 125 cg now with the lg X stabs. I might move it back to 129 to test it out.
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Old Feb 13, 2013, 01:10 AM
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United States, CA, Midway City
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Here are the plane configs with the tail volume.
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Old Feb 13, 2013, 07:04 AM
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United States, CA, San Diego
Joined Apr 2007
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Huh!?

Tuan, just go fly the damn thing and try to win!

"GO FLY"

Phil
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Old Feb 13, 2013, 08:27 AM
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Tuan,
You know I think the world of you... But would you agree that you could get the same results from trying to fly at to high an AOA in turbulent conditions. Also your model is very light and has light tips. The resulting feeling could be a model that shows more effects from turbulence. I am wondering if you increased your airspeed if you would see these stabs improve. LJ
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Old Feb 13, 2013, 09:46 AM
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United States, CA, Midway City
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Originally Posted by Larry Jolly View Post
Tuan,
You know I think the world of you... But would you agree that you could get the same results from trying to fly at to high an AOA in turbulent conditions. Also your model is very light and has light tips. The resulting feeling could be a model that shows more effects from turbulence. I am wondering if you increased your airspeed if you would see these stabs improve. LJ
Yep in turbulence I would want a higher airspeed (lower aoa). The S8025 with the stock stab's planform according to XFLR shows that re>75000 it performs well, but at lower re does not work as well as the thinner foils.
Quote:
Originally Posted by Phil Davy View Post
Tuan, just go fly the damn thing and try to win!

"GO FLY"

Phil
I hear ya Phil, unfortunately due to constant family obligations, I have a lot of desk time and very little field time these days. However, when I do get a chance to go out, my flights are very planned and purposeful so I am maximizing/optimizing my airtime
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Old Feb 13, 2013, 11:11 AM
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Watervliet, Mich.
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Originally Posted by Larry Jolly View Post
Hint I flew one and tested it and could not find any improvement... LJ
don't beat yourself up Larry. I'm sure some day, Tuan & Tuomo will loose there feel too....
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Old Feb 13, 2013, 12:56 PM
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Israel
Joined Nov 2006
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don't beat yourself up larry. I'm sure some day, tuan & tuomo will loose there feel too....


good one!
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Old Feb 14, 2013, 06:19 PM
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United States, CA, San Diego
Joined Apr 2007
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Nice!

Tuan, you know I am just rousing ya! I totally appreciate your situation. Your r&d skills are awsome and I think it is great! Keep it up and I hope all is well with the family.
Take care,
Phil




QUOTE=fnnwizard;24122559]Yep in turbulence I would want a higher airspeed (lower aoa). The S8025 with the stock stab's planform according to XFLR shows that re>75000 it performs well, but at lower re does not work as well as the thinner foils.

I hear ya Phil, unfortunately due to constant family obligations, I have a lot of desk time and very little field time these days. However, when I do get a chance to go out, my flights are very planned and purposeful so I am maximizing/optimizing my airtime[/QUOTE]
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