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amekler
Joined: 07 Oct 2010
Posts: 164
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 Posted: Sun Feb 14, 2016 4:25 am Post subject: best glide speed |
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I'm been looking at different v speeds
people are using for the RV10.
I see best glide 80 kts and other places 90 kts.
Also the Vx and Vy speeds seem to vary a lot.
Has anyone done actual testing for the numbers?
Alan
N668g 340 hrs
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rene(at)felker.com
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| Posted: Sun Feb 14, 2016 7:40 am Post subject: best glide speed |
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Yes I did testing....at least twice....and what I found out was that without
much more sophisticated test equipment I could not come up with a precise
number.
I settled with Vx of 78 and a Vy of 85 a Vgl of 80 (all knots).
But.........I never fly that way. I can not go very far climbing at 78 due
to engine heat and I never climb out at under 110. When practicing
emergency landing, I feel a lot better at 90 knots.
| Quote: | From what I can remember from the testing, airspeed did not have a great
effect on the performance.....to say it another way there is very little
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difference between a Vx of 78 and 80 but I did the math and it came out to
78.
Rene'
801-721-6080
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amekler
Joined: 07 Oct 2010
Posts: 164
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| Posted: Sun Feb 14, 2016 8:04 am Post subject: best glide speed |
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Rene,In my pilots manual that came with the plane these are the speeds listed.
<![endif]--> Normal 0 false false false EN-US JA X-NONE <![endif]--> <![endif]--> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} <![endif]-->
Vr 65 KTS
Vso 49 KTS
VS 67 KTS
BEST GLIDE 80KTS
VX 71 KTS
VY 104 KTS
I also climb out at least at 90 ktsAlan
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Tim Olson
Joined: 25 Jan 2007
Posts: 2879
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| Posted: Sun Feb 14, 2016 8:49 am Post subject: best glide speed |
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Take all numbers you received with the plane with a healthy grain of
salt. These are experimental planes, and you have no idea how
diligent the builder was at obtaining the numbers. You bought a plane
that was made by a non-certified company, with perhaps non-standard
techniques at times, and flown through an unknown test program of
unknown diligence. The ONLY way you will know the true numbers
are to go get them yourself in your own testing. In short, buying
a homebuilt, you need to not trust the original builder on ANYTHING, but
verify EVERYTHING for yourself, and put yourself through the whole
process of flight testing. There was absolutely nobody looking over the
test flight process in almost any homebuilt builders case, so you cannot
ensure that they even did the testing. In fact, with so many POH's out
there, I'm sure that a large portion of builders simply copy what someone
else has published.
I am pretty sure that just like Rene's comments, my numbers aren't
100% accurate. I had a very hard time really getting any reliably
repeatable numbers. Sure, with a bunch more time and testing I could
probably narrow it down, but as he said, there seems to not be that much
difference between a couple kts this way or that way. In the end, when it
comes to climb performance, I've learned to accept that in every situation
that I've flown so far, the airplane is simply more capable than most other
small GA airplanes, so Vx or Vy...it really doesn't make much difference.
The limiting factor as he noted is likely to be more the engine cooling. But
the RV-10 will get you away from the terrain in short order...at which point
you'll just use cruise climb anyway. Maybe a little more important is the
best glide, but that's where you'll have to test your aircraft as it is today,
in its current W&B configuration.
So in short, I just encourage everyone to go get your own numbers...don't
just cheat and ask other builders. These aren't certified planes, and there
is very little consistency in the exact airframe and W&B config, so it's just
plain safer, and good for you, to go do the testing yourself.
Tim
On 2/14/2016 10:00 AM, Alan Mekler MD wrote:
| Quote: | Rene, In my pilots manual that came with the plane these are the speeds listed.
<![endif]--> Normal 0 false false false EN-US JA X-NONE <![endif]--> <![endif]--> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} <![endif]-->
Vr 65 KTS
Vso 49 KTS
VS 67 KTS
BEST GLIDE 80KTS
VX 71 KTS
VY 104 KTS
I also climb out at least at 90 kts Alan
| Quote: | On Feb 14, 2016, at 7:25 AM, amekler <[url=mailto:amekler(at)metrocast.net]amekler(at)metrocast.net (amekler(at)metrocast.net)[/url]> wrote:
--> RV10-List message posted by: "amekler" <amekler(at)metrocast.net (amekler(at)metrocast.net)> I'm been looking at different v speeds people are using for the RV10. I see best glide 80 kts and other places 90 kts. Also the Vx and Vy speeds seem to vary a lot. Has anyone done actual testing for the numbers? Alan N668g 340 hrs Read this topic online here: http://forums.matronics.com/viewtopic.php?p=452808#452808
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amekler
Joined: 07 Oct 2010
Posts: 164
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| Posted: Sun Feb 14, 2016 9:19 am Post subject: best glide speed |
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Tim,
Thanks. I plan on getting my own numbers as i have no idea where the builder got these numbers.
Alan
ps. Do you have a link where I can find the recommended procedures to use?
[quote] On Feb 14, 2016, at 10:36 AM, Rene <rene(at)felker.com> wrote:
Yes I did testing....at least twice....and what I found out was that without
much more sophisticated test equipment I could not come up with a precise
number.
I settled with Vx of 78 and a Vy of 85 a Vgl of 80 (all knots).
But.........I never fly that way. I can not go very far climbing at 78 due
to engine heat and I never climb out at under 110. When practicing
emergency landing, I feel a lot better at 90 knots.
> From what I can remember from the testing, airspeed did not have a great
effect on the performance.....to say it another way there is very little
difference between a Vx of 78 and 80 but I did the math and it came out to
78.
Rene'
801-721-6080
--
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Jim Combs
Joined: 24 Jan 2010
Posts: 140
Location: Lexington, Ky
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| Posted: Sun Feb 14, 2016 10:47 am Post subject: best glide speed |
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Remember that best glide speed is FLAPS UP till you have the landing area made.
On Sun, Feb 14, 2016 at 11:00 AM, Alan Mekler MD <amekler(at)metrocast.net (amekler(at)metrocast.net)> wrote:
| Quote: | Rene,In my pilots manual that came with the plane these are the speeds listed.Â
Vr 65 KTS
Vso 49 KTS
 VS 67 KTS
  BEST GLIDE 80KTS
  VX 71 KTS
  VY 104 KTS
I also climb out at least at 90 ktsAlan
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_________________
RV-10 -> N312F - Flying as of 12/2008 |
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Bob Turner
Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA
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| Posted: Sun Feb 14, 2016 2:00 pm Post subject: Re: best glide speed |
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Remember that Vglide is tricky. It varies with aircraft weight (like the square root). Also, in the real world where you want to glide as far as possible over the ground with an engine out, the best indicated speed to use depends on the wind.
Mine seems to be around 80kias, no wind, gross weight.
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Bob Turner
RV-10 QB |
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dhmoose
Joined: 22 Nov 2010
Posts: 29
Location: Portland, OR
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| Posted: Mon Feb 15, 2016 7:12 am Post subject: Re: best glide speed |
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And remember to pull the prop out to extend glide during your testing, simulated, and real best glides. It makes a noticeable difference in performance and the flying characteristics. I was taught to only push the prop control back in when you need aerodynamic braking to avoid an overshoot.
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_________________
David Halmos
RV-10
Flying!
Portland, OR |
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