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601 HDS stall spead

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dbaker(at)sbuniv.edu
Guest

Posted: Wed Sep 05, 2007 5:38 pm Post subject: 601 HDS stall spead

I am test flying a 601 HDS and getting a stall speed of 75 MPH. What stall speed do you get with the HDS wing? Don

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leo(at)zuehlfield.com
Guest

Posted: Thu Sep 06, 2007 4:00 am Post subject: 601 HDS stall spead

Don,  Stall speed is relative to aircraft weight.  I tested with two GPS's running, just to be sure, and both read within .2 mph.  I made triangular runs in calm air on headings of 000, 120 and 240 degrees.  Tested at 2,000' msl +- 50'.  I recorded mag heading, OAT, IAS (at what appeared onset of mush on the VSI) and Ground speed.  Tested at 1,000 lbs., 1,500 lbs and 1,200 lbs.  Test runs were done at idle and about 40% power.  IAS was converted to CAL airspeed.  My POH says the plane stalls at 49 mph .  My pitot tube is ACS with an integral  static port mounted on the bottom of the left wing, just forward of the spar and about 2' outboard of the center section joint line.  FWIW my IAS will drop all the way to 37mph at a high "mush" (really high angle of attack) and then fall off to zero.

  

 Leo Gates

 N601Z, CH601HDS TDO

  

 [i]----

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daveaustin2(at)primus.ca
Guest

Posted: Thu Sep 06, 2007 5:23 am Post subject: 601 HDS stall spead

Don, what weight were you flying at?

My 601 with 912 stalled at 55 mph without VGs.  Now 50 with VGs.

I'm intereste to know why yours is so high.

Dave Austin  601HDS - 912, Spitfire Mk VIII

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larry(at)macsmachine.com
Guest

Posted: Thu Sep 06, 2007 5:33 am Post subject: 601 HDS stall spead

Don,

My HDS stalls at 50 mph fully loaded. I can't see how you can manage to 

stall out at 75.  That's the speed you should be on final approach.

Lightly loaded, full fueled header and just me it's 46 mph.  Perhaps you 

need to look closer at your airspeed indicator and pitot system.



Larry McFarland 601HDS at www.macsmachine.com

Don Baker wrote:

 	  Quote: 	
		   



 I am test flying a 601 HDS and getting a stall speed of 75 MPH.  What stall speed do you get with the HDS wing?  Don

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alhays(at)hickoryhillfarm
Guest

Posted: Thu Sep 06, 2007 5:53 am Post subject: 601 HDS stall spead

Hey Guys,

For what it's worth, 75 KPH equates to about 46 or 47 MPH.  Just 

coincidence?

Al Hays 601XL - starting fuselage

On Sep 6, 2007, at 9:32 AM, LarryMcFarland wrote:

 	  Quote: 	

 <larry(at)macsmachine.com>

 Don,

 My HDS stalls at 50 mph fully loaded. I can't see how you can manage 

 to stall out at 75.  That's the speed you should be on final approach.

 Lightly loaded, full fueled header and just me it's 46 mph.  Perhaps 

 you need to look closer at your airspeed indicator and pitot system.

 Larry McFarland 601HDS at www.macsmachine.com

 Don Baker wrote:

> 

>

> I am test flying a 601 HDS and getting a stall speed of 75 MPH.  What 

> stall speed do you get with the HDS wing?  Don

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grant.corriveau(at)telus.
Guest

Posted: Thu Sep 06, 2007 9:17 am Post subject: 601 HDS stall spead

My 601HDS stalls at about 58 to 60 mph.  I think that's pretty close  

to the book.  Assuming an aircraft close to the authorized Max.  

weight of 1200 (or 1300) lbs.



Two things I'd suggest you check -



1. ASI - is this an accurate reading?  Have you confirmed your ASI  

readings at slow speeds -i.e. with GPS or ground reference tests?



2. Aileron 'droop' ?  There is little guidance in the construction  

manual regarding the alignment of the ailerons with the rest of the  

wing.  I originally installed mine to align with the wing root  

fairing and to have a fairly 'flat' continuation of the wing at the  

tip.  But my cruising nose attitude was uncomfortably nose high.  So  

I tweaked both ailerons down a couple of degrees (i.e. extended the  

screw jack - but ensuring there are at least the required amount of  

threads in each endbolt).  Now they form a continued curving of the  

wing when viewed from the tip, and misalign slightly with the  

fairings (which I will eventually try to fix).  But the aircraft  

attitude in cruise is much better for forward vis, and as I say, the  

stall speed is about where it should be.



Previous discussions about this issue have mentioned that flying with  

this greater wing curvature gives slightly reduced airspeed, but for  

me it seems like a better tradeoff.



Grant

GHTF

601hdsCAM100

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jackandval

Joined: 18 Jul 2007
Posts: 21
Location: blairsville, GA

Posted: Fri Sep 07, 2007 3:34 pm Post subject: Re: 601 HDS stall spead

Sounds like the static port hose is loose or broken. This will cause a increase in airspeed indication. Seen it happen more then once.

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