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RV-10 Glide Ratio

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scottmschmidt(at)yahoo.co
Guest

Posted: Thu May 31, 2007 10:18 am Post subject: RV-10 Glide Ratio

Has anyone done some extensive glide ratio testing in their RV-10?  

 

Scott Schmidt

scottmschmidt(at)yahoo.com 



 [quote][b]

rv10flyer

Joined: 25 Aug 2009
Posts: 364

Posted: Sun Jun 09, 2013 1:06 pm Post subject: Re: RV-10 Glide Ratio

Solo, 40 gal, prop at coarse pitch, rpm 640 and airspeed 80 kias today, I was getting about 10:1.

_________________
Wayne G.

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Sun Jun 09, 2013 1:10 pm Post subject: RV-10 Glide Ratio

Usually best glide is much closer to Vy or even above Vy. I would expect 

it to be somewhere between 90&100kts.



On 6/9/2013 2:06 PM, rv10flyer wrote:

 	  Quote: 	
		   



 Solo, 40 gal, prop at coarse pitch, rpm 640 and airspeed 80 kias today, I was getting about 10:1.



 --------

 Wayne G.

 SB 12/01/2009-12/01/2011

 TT= 103





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=402344#402344






	


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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

kdbelue(at)charter.net
Guest

Posted: Sun Jun 09, 2013 1:15 pm Post subject: RV-10 Glide Ratio

Shut off the engine and the glide ratio will be lower. Stop the prop and it'll be better.



Sent from my iPhone



On Jun 9, 2013, at 4:06 PM, "rv10flyer" <wayne.gillispie(at)gmail.com> wrote:



 	  Quote: 	
		   

 

 Solo, 40 gal, prop at coarse pitch, rpm 640 and airspeed 80 kias today, I was getting about 10:1.

 

 --------

 Wayne G.

 SB 12/01/2009-12/01/2011

 TT= 103

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=402344#402344

dave.saylor.aircrafters(a
Guest

Posted: Sun Jun 09, 2013 1:23 pm Post subject: RV-10 Glide Ratio

Are there two terms for best glide like there are for best climb?  Bob Turner expounded on this a few weeks ago but I'll admit I didn't pay close enough attention. One would be to get you the furthest, another to keep you aloft for the greatest duration...or are they the same thing? 



I changed my emergency checklist a few years ago from 80 (KIAS) to 95 for best glide because it seemed that 95 got me further. But earlier I was pretty sure that 80 gave me the minimum sink rate.  Bob??

 

On Sunday, June 9, 2013, Kelly McMullen  wrote:

 	  Quote: 	
		  --> RV10-List message posted by: Kelly McMullen <kellym(at)aviating.com>

  

 Usually best glide is much closer to Vy or even above Vy. I would expect it to be somewhere between 90&100kts.

 

 On 6/9/2013 2:06 PM, rv10flyer wrote:

  	  Quote: 	
		   --> RV10-List message posted by: "rv10flyer" <wayne.gillispie(at)gmail.com>

 

 Solo, 40 gal, prop at coarse pitch, rpm 640 and airspeed 80 kias today, I was getting about 10:1.

 

 --------

 Wayne G.

 SB 12/01/2009-12/01/2011

 TT= 103

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=402344#402344

 

 

 

 

 

 

 

 

 

 

 	
 

 

 

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 No virus found in this message.

 Checked by AVG - www.avg.com

 

 

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 ====================================

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           -Matt Dralle, List Admin.

 t="_blank">http://www.matronics.com/contribution

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-- 

Dave Saylor

831-750-0284 CL

  [quote][b]

rv10flyer

Joined: 25 Aug 2009
Posts: 364

Posted: Sun Jun 09, 2013 4:00 pm Post subject: Re: RV-10 Glide Ratio

I also keep my TT AP "Min Airspd" set at 80 kts. If one has a lot of altitude it might help out and keeps us from stalling in an AP climb. With an actual engine out, we would gain a little more by opening the throttle. If I was at gross weight, I would shoot for 90 kts.

_________________
Wayne G.

Bob Turner

Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA

Posted: Sun Jun 09, 2013 8:07 pm Post subject: Re: RV-10 Glide Ratio

Minimum sink speed (maximum time before you hit the ground) is not the same as best glide (cover maximum horizontal distance before you hit the ground).

Minimum sink speed is at the "minimum power required" speed, and in most single engine GA airplanes is close to Vx and often just a few knots faster than stall speed Vs1.

Best glide speed in an ideal airplane is greater than Vy, but in every real certified GA single that I've been in the reverse is true. This is because virtually all aircraft have cruise props, and the increasing prop efficiency as speed increases in the Vy speed range pushes real world Vy to higher values.



Best glide (no wind) occurs at max L/D angle of attack. Therefore, it varies with weight (variation is as the square root of the weight, so, approximately, if you are under gross by 20%, then best glide is reduced (from gross weight number) by 10%.). At Wayne's weight I'd say 80 kias is about right.



In the real world, where you want to cover distance over the ground in a glide, the wind can come into play. With a tailwind, you want to go slower than published best glide speed, but never slower than minimum sink. With a headwind, increase speed, roughly by 40% of the wind speed if known.



As a side note, in many training situations where the cfi pulls the throttle and says "make the runway", the decrease in best speed because you are below gross weight and the increase in best glide because of the headwind tend to cancel out.

_________________
Bob Turner
RV-10 QB

dave.saylor.aircrafters(a
Guest

Posted: Sun Jun 09, 2013 9:31 pm Post subject: RV-10 Glide Ratio

So am I right in thinking that if you had an AOA indicator, and were able to glide at L/Dmax, then you could reduce speed on final to increase sink and not overshoot the landing spot?

  



For that matter you could also *increase* speed to increase sink, but then you'd touch down going faster.

  

Dave Saylor

831-750-0284 CL

 



On Sun, Jun 9, 2013 at 9:07 PM, Bob Turner <bobturner(at)alum.rpi.edu (bobturner(at)alum.rpi.edu)> wrote:

[quote]  --> RV10-List message posted by: "Bob Turner" <bobturner(at)alum.rpi.edu (bobturner(at)alum.rpi.edu)>

 

 Minimum sink speed (maximum time before you hit the ground) is not the same as best glide (cover maximum horizontal distance before you hit the ground).

 Minimum sink speed is at the "minimum power required" speed, and in most single engine GA airplanes is close to Vx and often just a few knots faster than stall speed Vs1.

 Best glide speed in an ideal airplane is greater than Vy, but in every real certified GA single that I've been in the reverse is true. This is because virtually all aircraft have cruise props, and the increasing prop efficiency as speed increases in the Vy speed range pushes real world Vy to higher values.

   

 Best glide (no wind) occurs at max L/D angle of attack. Therefore, it varies with weight (variation is as the square root of the weight, so, approximately, if you are under gross by 20%, then best glide is reduced (from gross weight number) by 10%.). At Wayne's weight I'd say 80 kias is about right.

   

 In the real world, where you want to cover distance over the ground in a glide, the wind can come into play. With a tailwind, you want to go slower than published best glide speed, but never slower than minimum sink. With a headwind, increase speed, roughly by 40% of the wind speed if known.

   

 As a side note, in many training situations where the cfi pulls the throttle and says "make the runway", the decrease in best speed because you are below gross weight and the increase in best glide because of the headwind tend to cancel out.

   

 --------

 Bob Turner

 RV-10 QB

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=402366#402366

 

 

 

 

 

 

 

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 " target="_blank">http://www.matronics.com/Navigator?RV10-List

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 k">http://forums.matronics.com

 ===========

 e -

           -Matt Dralle, List Admin.

 t="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 [b]

Bob Turner

Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA

Posted: Sun Jun 09, 2013 10:12 pm Post subject: Re: RV-10 Glide Ratio

Dave,

Yes that is correct. Typical approach speeds are at or less than best glide, so if the pilot pulls back on the stick with no power change, then once the transients die out, he'll be slower and have a steeper approach than before.

_________________
Bob Turner
RV-10 QB

rv10flyer

Joined: 25 Aug 2009
Posts: 364

Posted: Mon Jun 10, 2013 6:14 am Post subject: Re: RV-10 Glide Ratio

I don't have a real AOA and have never flown with one so I just practice a lot at solo and gross. The family understands the importance. I do not practice with full baggage, low fuel and at my aft limit with the family on board. I already did that with dogfood in phase 1. So far, no tendencies to enter a spin. I unload and raise the wing with rudder then gently add power back in. There is plenty of tail buffet warning without flaps. The GRT has a "derived" AOA that I calibrated, but I feel looking out the window with the feel in the seat and sound do more for me. I went out yesterday and did some power off stalls with/without flaps and level/30 deg banks. Also some no flap landings. After a while you can feel when you are at the "right" speed with or without flaps. Pulling that prop back to 640 rpm really makes a big difference in glide. I get a little engine shake at that low rpm, something I did not notice on David Maib's 3-blade during transition training. It does seem to have a slightly better glide, possibly due to less drag on the 2-blade and solo.

_________________
Wayne G.

Bob Turner

Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA

Posted: Mon Jun 10, 2013 8:10 am Post subject: Re: RV-10 Glide Ratio

Certainly drag is important, and others have mentioned ways to reduce it (low rpm on the prop, full throttle, stop the prop). Depending on what happened to the engine you may or may not be able to control these things.



Curiously, while weight affects the optimum glide speed it does not affect the glide distance, no wind. In a headwind you can glide further if you're heavy, vice versa in a tailwind.

_________________
Bob Turner
RV-10 QB

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