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jnjkimbell(at)HOTMAIL.COM
Guest

Posted: Thu Dec 07, 2006 2:38 pm Post subject: vg's

I just returned from flying my 701 for the first time since removing  the slats and adding VG's/  It was great.  A little too windy to check  all my numbers, but it does take off and land as short as it did before. Better  feel on landing. Stalls seem the same except power off, full flaps give me a  little more definite buffet.  Still no clean stall power off. Will report  actual numbers to the list after completing my tests.      Joe from FL     Those guys from down under seem to know what  they are doing.    do not archive

  



   [quote][b]

NYTerminat(at)aol.com
Guest

Posted: Thu Dec 07, 2006 6:53 pm Post subject: vg's

Joe,

  

 Congratulations, I am looking forward to your numbers. Was it hard laying  out and installing the VG's?

  

 Bob Spudis

 N701ZX  CH701/912S

  

 In a message dated 12/7/2006 5:40:34 P.M. Eastern Standard Time,  jnjkimbell(at)HOTMAIL.COM writes:

  	  Quote: 	
		          I just returned from flying my 701 for the first time since    removing the slats and adding VG's/  It was great.  A little too    windy to check all my numbers, but it does take off and land as short as it    did before. Better feel on landing. Stalls seem the same except power off,    full flaps give me a little more definite buffet.  Still no clean stall    power off. Will report actual numbers to the list after completing my    tests.     Joe from FL     Those guys    from down under seem to know what they are doing.    do not    archive

    



 	  Quote: 	
		  

	
	


 

  

  [quote][b]

Tebenkof(at)aol.com
Guest

Posted: Fri Dec 08, 2006 7:44 am Post subject: vg's

Joe,

  

 I have been off the list for a time.  Is this VGs instead of slats an  idea that has been talked about some?  Is there some reason to think VGs  may be superior?  Your numbers are eagerly awaited.

  

 I have considered using VGs in additon to the slats on my 701 (not yet  flying), but had not considered eliminating the slats.  Can you give me  more info on this idea?

  

 Jim Greenough

  [quote][b]

jnjkimbell(at)HOTMAIL.COM
Guest

Posted: Fri Dec 08, 2006 9:31 am Post subject: vg's

Jim, I got my ideas and vg's from the www.stolspeed.com site located in  Australia.  They have good numbers and what they say has certainly worked  for me so far.  Bad winds here so I hav'nt finised testing, but sure looks  great so far.  do not archive  Joe  

 [quote]   ---

mrbizi(at)yahoo.com
Guest

Posted: Fri Dec 08, 2006 10:50 am Post subject: vg's

Has anyone ever put VGs on the 601xl?   How do those numbers compare?

Thanks.



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Tebenkof(at)aol.com
Guest

Posted: Fri Dec 08, 2006 12:41 pm Post subject: vg's

Joe,

  

 thanks for the VG reference.  It looks quite interesting.

  

 Jim

  

 do not archive

  [quote][b]

amyvega2005(at)earthlink.
Guest

Posted: Sat Dec 09, 2006 11:25 am Post subject: vg's

they have put VGs on 601.  Check newsletter for 1996-1998.  few articles on the results. It seemed to do a good job of restricting the air from separating at slow speeds, therefore decreasing stall speed at landing and takeoff.



Juan



Juan



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milreed(at)directcon.net
Guest

Posted: Sun Dec 10, 2006 10:50 am Post subject: vg's

Jim

 I too am building a ch 701 and curious about  VG's.

 Speculating one might expect the VG's to slow the  stall speed at lower angles of attack, at higher angles when slats are operating  would the presents of VG's have an effect? Who has a wind tunnel? --- any test  pilots out there?

 Mil

  

    [quote][b]

JohnDRead(at)aol.com
Guest

Posted: Sun Dec 10, 2006 10:09 pm Post subject: vg's

Hi Mil:

             Build  it like the plans. The 701 is a well thought out design and the VGs will not  improve the plane. The folk messing with slat removal have not the faintest idea  of what they are doing from an aerodynamic sense! The removal of the slats  compromises the airfoil significantly. The slat is NOT an addition to the  airfoil rather the slot is a "tunnel" through the airfoil that improves the lift  coefficient of the airfoil. The increase in drag is minimal because when  the plane is not at a high angle of attack there is little or no flow  through the slot. Theory of Wing Sections by Abbot and Von Doenhoff  describes how a slot improves the lift coefficient. VGs do not improve lift  coefficient what they do do is to make a poor airfoil work a little better by  making the boundary layer stick to the airfoil a little further back on the  wing. 

     The gents in Australia who stared this mess should  make a call to Martin Simons who is an Aeronautical Prof. at the University  of Aukland he will help them understand.

  

 Regards, John Read

 CH701 in Colorado

  [quote][b]

NYTerminat(at)aol.com
Guest

Posted: Sun Dec 10, 2006 10:17 pm Post subject: vg's

John,

 There are getting to be too many flying without the slats to say that it  will not work!!!

  

 Bob Spudis

 N701ZX  CH701/912S, may have to try it myself

  

  

  

 In a message dated 12/11/2006 1:10:47 A.M. Eastern Standard Time,  JohnDRead(at)aol.com writes:

  	  Quote: 	
		     Hi Mil:

               Build    it like the plans. The 701 is a well thought out design and the VGs will not    improve the plane. The folk messing with slat removal have not the faintest    idea of what they are doing from an aerodynamic sense! The removal of the    slats compromises the airfoil significantly. The slat is NOT an addition to    the airfoil rather the slot is a "tunnel" through the airfoil that improves    the lift coefficient of the airfoil. The increase in drag is minimal    because when the plane is not at a high angle of attack there is little    or no flow through the slot. Theory of Wing Sections by Abbot and    Von Doenhoff describes how a slot improves the lift coefficient. VGs do not    improve lift coefficient what they do do is to make a poor airfoil work a    little better by making the boundary layer stick to the airfoil a little    further back on the wing. 

       The gents in Australia who stared this mess    should make a call to Martin Simons who is an Aeronautical Prof. at the    University of Aukland he will help them understand.

    

   Regards, John Read

   CH701 in Colorado

 	  Quote: 	
		  



p://www.aeroelectric.com/">www.aeroelectric.com

 href="http://www.buildersbooks.com/">www.buildersbooks.com

ttp://www.kitlog.com/">www.kitlog.com

ttp://www.homebuilthelp.com/">www.homebuilthelp.com

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

f="http://www.matronics.com/Navigator?Zenith-List">http://www.matronics.com/Navigator?Zenith-List



	
	


 

  

  [quote][b]

jnjkimbell(at)HOTMAIL.COM
Guest

Posted: Mon Dec 11, 2006 4:42 am Post subject: vg's

[quote] ---

jnjkimbell(at)HOTMAIL.COM
Guest

Posted: Mon Dec 11, 2006 5:07 am Post subject: vg's

John, I know you don't know me, but I just reported positively on how the  VG's actually worked.

 I did talk to an aeronautical engineer that did a lot of testing in the  early years of the VG idea and yes, your description of their properties agree  with his, except that he didn't think the airfoil Chris chose for the 701 was a  poor one, but a good one for STOL.   At least 6 people who have done  this change have noted increased cruise speed, so it is hard to believe that the  slats don't increase drag a bit more than minimal. 

  You must have some reason, other than what you stated to make such a  strong recommendation "build it like the plans", the ?VG's will not improve the  plane" right after reading reports that they do.

 I have over 5000 Hrs. in small aircraft, over two thousand hrs. instructing  is aircraft that weighed less than 900 lbs empty, so feel that I am qualified to  say.  "The 701 take off and landing are as short as they were  before".  It has been to windy to do accurate testing, but what I have  said, including that the cruise speed is faster, stands. 

 I will not get in a heated debate about this, but feel Mil needs more than  your opinion on how to build his airplane.  It is an experimental  plane.    That's all folks.     Joe from  FL

 [quote]   ---

rhartwig11(at)juno.com
Guest

Posted: Mon Dec 11, 2006 6:53 am Post subject: VG's

John,

How do you explain the success that owners of many 701's  with many hours

in the air are having with slats removed?  Their data (not speculation)

seems to suggest that slat removal works.  Hundreds of hours of

successful flight seems to be more than luck.  The "clone company" also

seems to believe it works.

Rich Hartwig

Waunakee, WI

rhartwig11(at)juno.com

John Bolding

Joined: 23 May 2006
Posts: 281

Posted: Mon Dec 11, 2006 8:55 am Post subject: vg's

John, you make a lot of blanket statements, the older I get  the less of those I make 'cause generally they don't hold water. I'll show you a  little of what I mean.

 [quote]    

    

   [quote]     ---

ggower_99(at)yahoo.com
Guest

Posted: Mon Dec 11, 2006 10:00 am Post subject: VG's

My personal point of view:   



For now, and dont know how long,  I will not experiment this "novelty".

There are so much flying scenarios possibles when flying...  Weather, crosswind landings,  windshear, etc.  that could affect the airplane (and pilot) by surprise, that I will not take that chance for a couple of mph either side of the speeds.  Is a Mayor Mod,  Not just like wheel pants and strut cleaning.  Now we cross (93) very near VNE,   

For more speed is why we are building the 601 XL, (also as is) and will try to keep both.



Once I see data from a wind tunnel or from ZAC, then I will probably think about it.  I  enjoy my 701 so much  "as is" that just sill be reading about this mod for a while.   I chosed this plane (701), I like it, I ejnoy it, why mess with it?



Saludos

Gary Gower

Flying from Chapala, Mexico.

701 912S   With Slats and  [quote][b]

NYTerminat(at)aol.com
Guest

Posted: Mon Dec 11, 2006 2:05 pm Post subject: VG's

Gary,

  

 There is always room for improvement. If the vg's give you the same stol  performance and allows you to go faster and uses less fuel, I don't see too many  downsides.

  

 Bob Spudis

  

 N701ZX  CH701/912S 92hrs

  

  

  

 In a message dated 12/11/2006 1:02:07 P.M. Eastern Standard Time,  ggower_99(at)yahoo.com writes:

  	  Quote: 	
		  Once I    see data from a wind tunnel or from ZAC, then I will probably think about    it.  I  enjoy my 701 so much  "as is" that just sill be reading    about this mod for a while.   I chosed this plane (701), I like it,    I ejnoy it, why mess with it?



Saludos

Gary Gower

Flying from    Chapala, Mexico.

701 912S   With Slats and  	  Quote: 	
		  

	
	


 

  

  [quote][b]

Avidmagnum

Joined: 18 Nov 2006
Posts: 19
Location: Wisconsin, Florida

Posted: Mon Dec 11, 2006 6:25 pm Post subject: Re: vg's

Hi Joe



I also removed the slats from my 701 Amphib and put on the feathers VGs. I've been flying the wings off it the last few days. I left the brackets on till I was sure that I would not change my mind. Today I cut off the slat brackets...I'm that convinced that the vg's (FOR ME) are the way to go. I liked my 701 Amphib but 85 mph at 5500 was not doing it for me. My buddy with the Rans s-7 with the same floats, engine , warp prop and heavier does 105 mph.  With vg's and no slats I can now do 92 mph or even beter fly at 85 with less rpm.  I also find the aircraft "nicer" to fly...not that it was ever bad.  



 I also do not want to argue with anyone. So if you like your slats.......please keep them......and for anyone still building I will be glad to sell you a nice set.  Smile and have a nice day!   Tom

lgold(at)quantum-associat
Guest

Posted: Mon Dec 11, 2006 11:13 pm Post subject: vg's

Avidmagnum (?)



I'm ready to start building my slats. What condition are yours slats in, and

how much do you want for them (include shipping to the San Francisco Area)?

Anything to speed up the work!



With all this VG talk, I spoke with Michael Heintz last week. Michael, one

of Chris Heintz's sons, has a shop north of here in Cloverdale Ca where he

builds 601's and 701s. I respect and trust his opinion regarding the 701. 



Michael cautioned against substituting leading Edge slats with VGs, saying

that even design changes may lead to a domino effect, and removing the slats

is NOT a "small" change! He asked why would you even entertain the idea of

becoming a guinea pig for some unknown armchair designer or the manufacturer

of a gadget who, while they may "make a good case", have little CH 701

experience? 

 

He qualified his opinion saying that personally he as no experience with VGs

on the 701. He also said that there are hundreds of 701 successfully flying

with slats; their owners don't complain that the stall speed of the aircraft

is too fast or the take-off run is too long... again strongly recommending

that I stick with the plans! 



I am a graduate engineer. Although I have not done any analysis on the wing

strength with or without slats, it is obvious that slats do add some

strength to the wings. I would want to see wing stress test data with VGs

before succumbing to the glitter of a few more knots. While the promise of a

few knots is appealing, I am more concerned that the wings stay put in

unforeseen marginal weather or when I'm forced to make tight maneuvers.



Regards,

Les 



[quote] --

secatur

Joined: 02 Nov 2006
Posts: 50
Location: New Zealand

Posted: Tue Dec 12, 2006 3:08 am Post subject: Re: vg's

Well, I guess I'll just have to change my mind and build the slats and throw these VG's away !

1700+ hours of independant, documented testing WITHOUT 1 negative report ain't gonna convince me!

And when my 701 is finished I will park it right next to my Wright Flyer, and my Model T ford (Black of course!) right under the big sign that says "EXPERIMENTAL..do not change or alter ever...or else!!"



ps: Can somebody please post some BAD results with VG's instead of Slats .... so I can feel justified??



Wowie Zowie !

nandrand(at)xtra.co.nz
Guest

Posted: Tue Dec 12, 2006 4:00 am Post subject: vg's

Hi John.

          I note your comments on  VG's and slats/slots, how do you explain the apparent improvements in Vc. and  stall??  Is it that, Zenith had an already good STOL wing, and to increase  the angle of attack stuck a slat/slot on the leading edge???? As a matter of  interest, I live 10mins drive from Auckland University, I'll have a chat with  Martin Simons, it may be of some interrst to our local flyers!!  

                                        Kind Regards,  Fly Safe    Noel

 [quote]   ---

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