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czechsix(at)juno.com
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 Posted: Mon Apr 24, 2006 5:23 pm Post subject: Datapoint for Fairings Speed Improvement |
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Guys,
I know others have commented on how much speed an RV picks up when fairings are installed. Just for kicks though I took some data in my RV-8A without any fairings and then again with wheel pants, gear leg and intersection fairings installed. My data was taken with four-way GPS runs using one of the calculators on Kevin Horton's website (the advantage of the four-way run vs. three-way is that the spreadsheet gives you a sanity check to show how good/bad your data is).
Anyway, at 4000' density altitude, power set to 24 squared and mixture 50 ROP, I saw an 18 kt gain in TAS when when fairings were put on. I would imagine that the speed increase would be less in a taildragger since there are only two big gear legs/wheels to clean up. I wish now I'd taken some numbers at full power and lower altitude...I bet the speed increase would have been at least 20 kts. Even so I've told several of my spam-can buddies and they can't believe that fairings would make that much difference.
Cool!
--Mark Navratil
Cedar Rapids, Iowa
RV-8A N2D with O-360-A1A and blended Hartzell
Flying 29.2 hours now....
Guys,
I know others have commented on how much speed an RV picks up when fairings are installed. Just for kicks though I took some data in my RV-8A without any fairings and then again with wheel pants, gear leg and intersection fairings installed. My data was taken with four-way GPS runs using one of the calculators on Kevin Horton's website (the advantage of the four-way run vs. three-way is that the spreadsheet gives you a sanity check to show how good/bad your data is).
Anyway, at 4000' density altitude, power set to 24 squared and mixture 50 ROP, I saw an 18 kt gain in TAS when when fairings were put on. I would imagine that the speed increase would be less in a taildragger since there are only two big gear legs/wheels to clean up. I wish now I'd taken some numbers at full power and lower altitude...I bet the speed increase would have been at least 20 kts. Even so I've told several of my spam-can buddies and they can't believe that fairings would make that much difference.
Cool!
--Mark Navratil
Cedar Rapids, Iowa
RV-8A N2D with O-360-A1A and blended Hartzell
Flying 29.2 hours now....
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Dale Ensing
Joined: 11 Jan 2006
Posts: 571
Location: Aero Plantation Weddington NC
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| Posted: Mon Apr 24, 2006 6:13 pm Post subject: Datapoint for Fairings Speed Improvement |
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Mark,
Your numbers before and after all fairings were installed are very similar
to what I experienced on my 6A.
Dale Ensing
do not archive
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Dale Ensing
RV-6A
Aero Plantation
Weddington NC |
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martin(at)gbonline.com
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| Posted: Tue Apr 25, 2006 7:26 pm Post subject: Datapoint for Fairings Speed Improvement |
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Mark,
Welcome to the world of faster airplanes. A giant engine helps, but a
CLEAN, LIGHT airplane always wins the speed contests. I have an RV8 and
during my initial testing, I experimented with various gear leg to fuselage
fairings and found that a considerable speed increase is available at this
junction. An easy way to test the efficiency of the fairing is to spray
some waste oil on the fuselage in the area where the landing gear attachs,
and then go up an fly the airplane. If the fairing is efficient, you will
see perfectly shaped oil lines on the side of the fuselage depicting the
airflow (just like the pictures in the technical magazines). If the flow
lines are erattic, you know you need to try some variations in shape of the
fairing. As a general statement, the upper gear to fuse fairing will be
more efficient when it has a lead is between 1 and 2 inchs long with a long
,narrow taper to the gear leg. A side note: some RV8s experience a sliight
tail shudder when stall landing. If the above fairing is correct, the tail
shudder disappears.
Good luck with your project and hope to see you and others in the Air
Venture Races.
Dick Martin
RV8 N233M
the fast one
---
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Jerry Grimmonpre'
Joined: 09 Jan 2006
Posts: 144
Location: Huntley, Illinois 60142
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| Posted: Wed Apr 26, 2006 4:44 am Post subject: Datapoint for Fairings Speed Improvement |
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Dick ...
Can you expand on the description starting with:
As a general statement, the upper gear to fuse fairing will be
| Quote: | more efficient when it has a lead is between 1 and 2 inchs long with a
long
,narrow taper to the gear leg.
|
Pictures would be good if you have them.
Thanks ...
Jerry Grimmonpre'
RV8A Electrical
| Quote: |
Mark,
Welcome to the world of faster airplanes. A giant engine helps, but a
CLEAN, LIGHT airplane always wins the speed contests. I have an RV8 and
during my initial testing, I experimented with various gear leg to
fuselage
fairings and found that a considerable speed increase is available at this
junction. An easy way to test the efficiency of the fairing is to spray
some waste oil on the fuselage in the area where the landing gear attachs,
and then go up an fly the airplane. If the fairing is efficient, you will
see perfectly shaped oil lines on the side of the fuselage depicting the
airflow (just like the pictures in the technical magazines). If the flow
lines are erattic, you know you need to try some variations in shape of
the
fairing. As a general statement, the upper gear to fuse fairing will be
more efficient when it has a lead is between 1 and 2 inchs long with a
long
,narrow taper to the gear leg. A side note: some RV8s experience a
sliight
tail shudder when stall landing. If the above fairing is correct, the
tail
shudder disappears.
Good luck with your project and hope to see you and others in the Air
Venture Races.
Dick Martin
RV8 N233M
the fast one
|
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http://www.matronics.com/Navigator?RV-List |
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martin(at)gbonline.com
Guest
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| Posted: Wed Apr 26, 2006 5:57 pm Post subject: Datapoint for Fairings Speed Improvement |
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Jerry,
Call me at 920 619 6968 and I will explain in detail. It would take a week
to type out an explanation on email.
Dick Martin
RV8 N233M
the fast one
---
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