Matronics Email Lists :: View topic - Question to no pwr clean stall speeds

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Question to no pwr clean stall speeds
Goto page 1, 2 Next

Matronics Email Lists Forum Index -> RV10-List

View previous topic :: View next topic

Author Message

Mike Whisky

Joined: 05 Jun 2006
Posts: 336
Location: Switzerland

Posted: Wed Oct 02, 2013 11:05 am Post subject: Question to no pwr clean stall speeds

Hi,



I tested today my no power stall speeds at gross 2700 lbs and cg 113.8 in

She stalled clean at 73 KIAS which is about 13 kt more than expected. 

I just want to confirm that the 60 KIAS are achieved with reflex flap (-3) and not with 0° flaps? Controls were at the stop and buffeting started at 75-76 KIAS

Regards

Mike

_________________
RV-10 builder (flying)
#511

rene(at)felker.com
Guest

Posted: Wed Oct 02, 2013 11:29 am Post subject: Question to no pwr clean stall speeds

When I tested, I settled on 49 KIAS for landing (full flaps) and 59 KIAS

clean (-3 degrees).  I do not remember my AFT CG numbers being that much

different.....surely not 13 knots.  I tested outside the aft envelop, but I

cannot remember by how much.



When I tested my airspeed indicator, I think I was only a couple of knots

off at 170 or so knots.



73 seems real fast......



Have you flown some GPS boxes, or triangles, to check you airspeed

indicator?  Have you tested your static system? 



Good luck, if you really are at 73 knots, your landings must be real

long.......



Rene' Felker

N423CF

801-721-6080



--

Bob Turner

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

Posted: Wed Oct 02, 2013 11:35 am Post subject: Re: Question to no pwr clean stall speeds

That does sound a little high. My testing came in at 64 KIAS, flaps in reflex (full up). Remember that IAS typically is lower than CAS at high (stall) angle of attack due to the pitot tube not being straight on. I cannot vouch for the accuracy of my airspeed at these low numbers. I do know that at cruise speeds they are within a knot or two of correct.

OTOH I do not know where your ideal of 60 kias came from. Van's claims gross weight stall at 55 KIAS with full flaps.

Have you verified your airspeed readings? It's surprisingly easy for them to be off if your static port is not reading true static pressure. My guess is that it is much easier to have your IAS off than to have the stall speeds, which are fixed by the structure, off. Unless of course your scales were off and you are much heavier than you believe, which seems unlikely.

_________________
Bob Turner
RV-10 QB

Tim Olson

Joined: 25 Jan 2007
Posts: 2872

Posted: Wed Oct 02, 2013 11:40 am Post subject: Question to no pwr clean stall speeds

Before you do that, have you done the 3 way or 4 way GPS airspeed 

calibration

to verify your airspeed is correct?  It would be very hard for a plane 

to be that

far out of norm with other RV-10's, so there is likely some pitot-static 

error

or something else that is causing the number to be high.  Also, you

talk about full stop and buffeting, but not if you were actually into 

the stall.

The 60-62kt numbers you see are probably at full stall, past just the 

buffeting.



Tim

On 10/2/2013 2:05 PM, Mike Whisky wrote:

 	  Quote: 	
		   



 Hi,



 I tested today my no power stall speeds at gross 2700 lbs and cg 113.8 in

 She stalled clean at 73 KIAS which is about 13 kt more than expected.

 I just want to confirm that the 60 KIAS are achieved with reflex flap (-3) and not with 0° flaps? Controls were at the stop and buffeting started at 75-76 KIAS

 Regards

 Mike

Mike Whisky

Joined: 05 Jun 2006
Posts: 336
Location: Switzerland

Posted: Wed Oct 02, 2013 11:56 am Post subject: Re: Question to no pwr clean stall speeds

Thanks for the answers. I am was referring to clean stall speed, I might not have reached a full stall and was probably in caught buffeting down.

(at)Tim I did my airspeed calibration runs and they were within limits. 



However from an engineering point of view that is the only possible error source as the wing is the same as anyone else's. I guess I will redo my airspeed calibration run tomorrow. 



One more thing what AOA number does it show in case you use an AFSpro AOA or EFIS at stall no flaps? With full flaps I have AOA 150 and 56 kt airspeed.



Mike

_________________
RV-10 builder (flying)
#511

carl.froehlich(at)verizon
Guest

Posted: Wed Oct 02, 2013 12:52 pm Post subject: Question to no pwr clean stall speeds

Some thoughts:

-  The plane is very different at gross, so a stall higher than the typical

60 knots would be expected.

- 13 knots higher however is more than I ever got during weight testing.  

-  If you assume airspeed is off but airspeed calibration in level flight is

good, then I'd look at the static system for the error.  Perhaps you are

creating a low pressure area near your static ports during the stall.



If everything else checks out, perhaps you can try stall with the static

line temporarily disconnected (as in you are using the inside of the plane

for static pressure) as a test.



On the RV-8A I originally had a dual pitot/static tube.  At high angles of

attack the static port started to get ram air.  The result was opposite of

yours - I was at '0' airspeed and still flying.  I later moved the ports to

the traditional  position but again encounter an error that demonstrated

itself as higher than actual airspeed indication and an altitude error.  I

now use a couple of 3/16" round head rivets with a 1/16" hole drilled in the

center for the static ports.  Simple install and no error.



Carl

--

Bob Turner

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

Posted: Wed Oct 02, 2013 2:30 pm Post subject: Re: Question to no pwr clean stall speeds

Your full flap number seems about right.

The flaps are very effective but I do not think they reduce the stall speed by 73-56=17 kts. Note that this would mean that the flaps increased the overall lift coeficient by nearly 70%!



Here's an easy test: I think your efis will calculate a headwind or tailwind component for you. At an altitude high enough that the wind stays constant, hold altitude and heading, and start at the airspeed where you previously checked it. Note headwind component. Smoothly slow to 70 kias, see if headwind component changes as you near 73 kias. If so there's an airspeed calibration problem, likely the static port.

_________________
Bob Turner
RV-10 QB

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Wed Oct 02, 2013 4:37 pm Post subject: Question to no pwr clean stall speeds

Does anyone know the speed difference between start of buffet to actual stall break?



On Wed, Oct 2, 2013 at 12:56 PM, Mike Whisky <rv-10(at)wellenzohn.net (rv-10(at)wellenzohn.net)> wrote:

  	  Quote: 	
		  --> RV10-List message posted by: "Mike Whisky" <rv-10(at)wellenzohn.net (rv-10(at)wellenzohn.net)>

  

 Thanks for the answers. I am was referring to clean stall speed, I might not have reached a full stall and was probably in caught buffeting down.

 (at)Tim I did my airspeed calibration runs and the were within limits. However from an engineering point of view that is the only possible error source as the wing is the same as anyone else's. I guess I will redo my airspeed calibration run tomorrow.

  

 Mike

 

 --------

 RV-10 builder (flying, test phase)

 #511

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=409708#409708

 

 

 

 

 

 

 

 ===========

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

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

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

 ===========

 

 

 

 	


-- 



 - sent from the microchip implanted in my forearm

  

  [quote][b]

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

rv10flyer

Joined: 25 Aug 2009
Posts: 364

Posted: Wed Oct 02, 2013 7:07 pm Post subject: Re: Question to no pwr clean stall speeds

 	  Mike Whisky wrote: 	
		  Hi,



I tested today my no power stall speeds at gross 2700 lbs and cg 113.8 in

She stalled clean at 73 KIAS which is about 13 kt more than expected. 

I just want to confirm that the 60 KIAS are achieved with reflex flap (-3) and not with 0° flaps? Controls were at the stop and buffeting started at 75-76 KIAS

Regards

Mike 	




Up high, no power...mine stalls at 54 kias full gross, full flaps, near aft cg limit with family and baggage. Our descent rate is 900 fpm.



It stalls at 64 kias with flaps set to reflex. With full flaps there is very little to no tail shake before stalling due to increased wing downwash. This can make it very dangerous in the pattern if the incorrect response is made. With no flaps, I have to hold stick full aft with "rocking horse" motion as tail gets into wing wake/downwash. Difficult to get into a deep stall with no flaps. Our descent rate is 1400 fpm. 



Flying solo, cg about 3/4" aft of fwd limit and full fuel, these numbers drop about 6 kias.



On landing, at stall 1' or less AGL, my IAS is about 8 kts higher. Of course I don't pay any attention to ASI once below 10'-15' or so. 



Just FYI...We get about 2 nm glide for every 1000' agl with prop full aft/coarse pitch, engine at idle, mixture leaned for altitude. We descend at 500 fpm at 80-85 kias. Glide ratio= 10:1. With prop forward Glide Ratio goes to 8.5:1 and descent rate to 800 fpm.



During stall practice my ailerons still have a little effectiveness, but I always raise the wing with rudder. We practice as often as possible.

_________________
Wayne G.

Last edited by rv10flyer on Fri Oct 04, 2013 7:03 pm; edited 1 time in total

rv10flyer

Joined: 25 Aug 2009
Posts: 364

Posted: Wed Oct 02, 2013 7:18 pm Post subject: Re: Question to no pwr clean stall speeds

[quote="Kelly McMullen"]Does anyone know the speed difference between start of buffet to actual stall break?



On Wed, Oct 2, 2013 at 12:56 PM, Mike Whisky <rv> wrote:

  	  Quote: 	
		  --> RV10-List message posted by: "Mike Whisky" <rv>

  

 Thanks for the answers. I am was referring to clean stall speed, I might not have reached a full stall and was probably in caught buffeting down.

 (at)Tim I did my airspeed calibration runs and the were within limits. However from an engineering point of view that is the only possible error source as the wing is the same as anyone else's. I guess I will redo my airspeed calibration run tomorrow.

  

 Mike

 

 --------

 RV-10 builder (flying, test phase)

 #511

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=409708#409708

 

 

 

 

 

 

 

 ===========

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

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

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

 ===========

 

 

 

 	


-- 



 - sent from the microchip implanted in my forearm

  

   	  Quote: 	
		  [b] 	




See my last post too. No flaps, full gross, near aft limit...6 knots. With full flaps, there is very little warning before my right wing drops. Just release pressure and it recovers.

_________________
Wayne G.

Last edited by rv10flyer on Fri Oct 04, 2013 3:32 pm; edited 2 times in total

RVflyHI

Joined: 01 Sep 2010
Posts: 9

Posted: Wed Oct 02, 2013 7:25 pm Post subject: Question to no pwr clean stall speeds

I have these numbers on my phone for 2300 lbs. I'm on the road right now. For some reason I just have these numbers   

Of course the vans stall tab can be changed but these represent the difference between stall horn and actual stall. 

Flaps 30 stall 43 horn 60

Flaps 20 stall 48 horn 62

Flaps 0     stall 53 horn 63

Flaps -3   stall 57 horn 67



Sent from my iPhone



On Oct 2, 2013, at 20:36, Kelly McMullen <apilot2(at)gmail.com (apilot2(at)gmail.com)> wrote:

[quote]Does anyone know the speed difference between start of buffet to actual stall break?



On Wed, Oct 2, 2013 at 12:56 PM, Mike Whisky <rv-10(at)wellenzohn.net (rv-10(at)wellenzohn.net)> wrote:

  	  Quote: 	
		  --> RV10-List message posted by: "Mike Whisky" <rv-10(at)wellenzohn.net (rv-10(at)wellenzohn.net)>

  

 Thanks for the answers. I am was referring to clean stall speed, I might not have reached a full stall and was probably in caught buffeting down.

 (at)Tim I did my airspeed calibration runs and the were within limits. However from an engineering point of view that is the only possible error source as the wing is the same as anyone else's. I guess I will redo my airspeed calibration run tomorrow.

  

 Mike

 

 --------

 RV-10 builder (flying, test phase)

 #511

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=409708#409708

 

 

 

 

 

 

 

 ===========

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

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

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

 ===========

 

 

 

 	


-- 



 - sent from the microchip implanted in my forearm

  

   	  Quote: 	
		  



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

://www.matronics.com/Navigator?RV10-List

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

cs.com

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

matronics.com/contribution

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



	


[b]

Mike Whisky

Joined: 05 Jun 2006
Posts: 336
Location: Switzerland

Posted: Thu Oct 03, 2013 6:02 am Post subject: Re: Question to no pwr clean stall speeds

Update:

I did a speed validation run today followed by a clean stall attempt. 

I actually can't get it to break same as rv10flyer stated its a rocking horse ride and you loose just altitude. I guess I will have to move the cg backwards to produce a stall break. The controls were at the backward stop. 

I will slowly move the c.g. back. 



Mike

_________________
RV-10 builder (flying)
#511

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Thu Oct 03, 2013 6:41 am Post subject: Question to no pwr clean stall speeds

At some point you will need to test the rear c.g. limit at full gross. I certainly agree with approaching that slowly to avoid any nasty surprises. It is likely useful to know how differently the plane handles stall at forward and aft c.g. limits. I've heard that if one fully explores the c.g. envelope and checks all the other flight characteristics and airspeeds that you will use up most or all of the 40 hours.

 

On Thu, Oct 3, 2013 at 7:02 AM, Mike Whisky <rv-10(at)wellenzohn.net (rv-10(at)wellenzohn.net)> wrote:

  	  Quote: 	
		  --> RV10-List message posted by: "Mike Whisky" <rv-10(at)wellenzohn.net (rv-10(at)wellenzohn.net)>

  

 Update:

 I did a speed validation run today followed by a clean stall attempt.

 I actually can't get it to break same as rv10flyer stated its a rocking horse ride and you loose just altitude. I guess I will have to move the cg backwards to produce a stall break. The controls were at the backward stop.

  I will slowly move the c.g. back.

 

 Mike

 

 --------

 RV-10 builder (flying, test phase)

 #511

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=409759#409759

 

 

 

 

 

 

 

 ===========

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

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

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

 ===========

 

 

 

 	


-- 



 - sent from the microchip implanted in my forearm

  

  [quote][b]

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

napolin(at)me.com
Guest

Posted: Thu Oct 03, 2013 10:16 am Post subject: Question to no pwr clean stall speeds

I have done so stall testing this past month.  I saw little difference between reflex and 0 deg flaps.  Dont remember exactly but maybe 2 knots or so.  Stall at about 2500 lb was at low sixties.



You might want to also verify your weight and cg calculations prior to your next flight.



Niko



Nikolaos Napoli



 	  Quote: 	
		   On Oct 2, 2013, at 3:05 PM, Mike Whisky <rv-10(at)wellenzohn.net> wrote:

 

 

 

 Hi,

 

 I tested today my no power stall speeds at gross 2700 lbs and cg 113.8 in

 She stalled clean at 73 KIAS which is about 13 kt more than expected. 

 I just want to confirm that the 60 KIAS are achieved with reflex flap (-3) and not with 0° flaps? Controls were at the stop and buffeting started at 75-76 KIAS

 Regards

 Mike

 

 --------

 RV-10 builder (flying, test phase)

 #511

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=409702#409702

Mike Whisky

Joined: 05 Jun 2006
Posts: 336
Location: Switzerland

Posted: Tue Oct 15, 2013 6:33 am Post subject: Re: Question to no pwr clean stall speeds

I wanted to report the latest results of my stall testing we move the c.g. slowly backwards to 115.2 (full fuel) and 2700 lbs MTOW. Whic. Would giv me a c.g. of 116.18 ( low fuel).

The plane flies until 69 KIAS but won't break into a stall. It is a "rocking horse" ride down. From what I read others extropolate the numbers to 2700 lbs and did tests with less weight but did anyone fly with 2700 lbs to a stall break with reflex flaps (clean)?



Mike

_________________
RV-10 builder (flying)
#511

carl.froehlich(at)verizon
Guest

Posted: Tue Oct 15, 2013 8:01 am Post subject: Question to no pwr clean stall speeds

The stall speed still sounds high.



On the 8A I noted my landings were taking up way too much runway when using

the same approached I used for years.  I built the attached simple airspeed

calibration rig and found the airspeed meter was reading correctly at

cruise, but several knots high at speeds below 80 knots or so.  How I fixed

it to read accurately is another story.



As a side note, the rig is perhaps $5 of tygon tubing but it is dead on

accurate.  I used it before first flight on the 10 to make sure the EFIS and

the steam gauge airspeed meter were reading accurately across the speed

range.  It is also useful to check for and correct pitot and static line

leaks.



Carl 



--

Manometer.pdf

Description:

Download

Filename:

Manometer.pdf

Filesize:

17.53 KB

Downloaded:

274 Time(s)

Bob Turner

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

Posted: Tue Oct 15, 2013 8:38 am Post subject: Re: Question to no pwr clean stall speeds

For our Swiss friend, note that the scale on Carl's gizmo is in inches on the left side. Also, the air source is low pressure - 1 or 2 psi max. Do not use your shop compressor. In fact, if your sustem is leak free, you do not need an air source at all. Just raise the free end of the water tube, and read the difference between the two sides on Carl's scale.

_________________
Bob Turner
RV-10 QB

carl.froehlich(at)verizon
Guest

Posted: Tue Oct 15, 2013 10:42 am Post subject: Question to no pwr clean stall speeds

I use one of those blood pressure squeeze bulbs.  It is perfect for this.



Carl



--

rv10flyer

Joined: 25 Aug 2009
Posts: 364

Posted: Tue Oct 15, 2013 4:50 pm Post subject: Re: Question to no pwr clean stall speeds

 	  Mike Whisky wrote: 	
		  I wanted to report the latest results of my stall testing we move the c.g. slowly backwards to 115.2 (full fuel) and 2700 lbs MTOW. Whic. Would giv me a c.g. of 116.18 ( low fuel).

The plane flies until 69 KIAS but won't break into a stall. It is a "rocking horse" ride down. From what I read others extropolate the numbers to 2700 lbs and did tests with less weight but did anyone fly with 2700 lbs to a stall break with reflex flaps (clean)?



Mike 	




Our RV-10 cg range is 8.4-16.8" aft of wing leading edge. During our full gross xc flights, our cg at takeoff is 15.93". With a 4.5 hr trip and 10 gal remaining our cg is at 16.73". We don't recommend trying to squeeze anymore in the baggage area unless you are into exciting landings. Van's aft cg limit is right on the money. 



To your question...64 kts flaps reflex as noted above. We have elevator stops at max range per plans which helps. We have to move stick aft a little quicker to get it to break, but it will. Boy, we really love this plane!

_________________
Wayne G.

rv10flyer

Joined: 25 Aug 2009
Posts: 364

Posted: Tue Oct 15, 2013 4:51 pm Post subject: Re: Question to no pwr clean stall speeds

 	  Mike Whisky wrote: 	
		  I wanted to report the latest results of my stall testing we move the c.g. slowly backwards to 115.2 (full fuel) and 2700 lbs MTOW. Whic. Would giv me a c.g. of 116.18 ( low fuel).

The plane flies until 69 KIAS but won't break into a stall. It is a "rocking horse" ride down. From what I read others extropolate the numbers to 2700 lbs and did tests with less weight but did anyone fly with 2700 lbs to a stall break with reflex flaps (clean)?



Mike 	




Our RV-10 cg range is 8.4-16.8" aft of wing leading edge. During our full gross xc flights, our cg at takeoff is 15.93". With a 4.5 hr trip and 10 gal remaining our cg is at 16.73". We don't recommend trying to squeeze anymore in the baggage area unless you are into exciting landings. Van's aft cg limit is right on the money. 



To your question...64 kts flaps reflex as noted above. We have elevator stops at max range per plans which helps. We have to move stick aft a little quicker to get it to break, but it will. Boy, we really love this plane!

_________________
Wayne G.

Display posts from previous:

	Matronics Email Lists Forum Index -> RV10-List	All times are GMT - 8 Hours Goto page 1, 2 Next
Page 1 of 2

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum