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Elevator Authority

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vgstol(at)bigpond.net.au
Guest

Posted: Wed Aug 20, 2008 6:34 pm Post subject: Elevator Authority

Gday All,

 I'm a bit late in replying to this thread because  I've been away to Oshkosh followed by a family reunion in Canada.

  

 It was really heartening at Oshkosh to see  that all three display aircraft at the Zenith stand had my Stolspeed VGs  installed on the elevators.  I knew that chief pilot Roger had been  recommending them to customers for some time, and orders have been  increasing.  Roger suggested that Zenith would like to sell the Stolspeed  VGs direct on their website.  I agreed with this, and we are setting up  that system now.  It may take a little while until that is up and running,  but in the meantime you can order direct from the manufacturer at

  http://www.stolspeed.com/ordering-feathers-vgs/

  

 At Stolspeed we discovered the idea of placing  VGs directly on the elevator rather than just on the horiz stab, and did all the  testing and proving.  The results are a dramatic improvement in elevator  authority, as verified by Roger at Zenith.  The story with photos can  be seen at 

 http://www.stolspeed.com/tail-feathers/ ,  

 and installation instructions can be seen  at

  http://www.stolspeed.com/placing-vgs-on-the-701/ 

 and 

 http://www.stolspeed.com/installing-feathers-vgs/ .

  

 I believe that at Stolspeed we have more real  life experience and have done more real life experimenting, including  controlled engineering testing and video tuft testing than anyone else in the  field of applying VGs to light recreational aircraft.  I already have  8 hours of video tuft testing on file, and since each test uses only  about 10 minutes of video, that's a lot of flights.  I flew 240 hrs last  year, much of that in testing and evaluation on 701, Savannah, and Rans S7  aircraft.  Still going at it and lots more to come.  Working on fuel  comsumption and fuel efficiency right now, and getting some very interesting  results.  The problem is getting enough time on the computer to publish  these results - I'd far rather be flying and testing......  So  right now I'm off to the airfield again.......

  

 Tailwinds always,

 JG

   [quote][b]

kmccune

Joined: 22 Sep 2007
Posts: 577
Location: Wisconsin, USA

Posted: Thu Aug 21, 2008 7:03 pm Post subject: Re: Elevator Authority

Hi John, 



Glad to hear your home safe, short trip for me (at)200 miles. I don't think I'd ever go around the world for an airplane get together, so hats of to you and all those that do this every year!  



Now that world rounder thing and the VG fuel savings and extra fuel tanks and..... now thats another story for after retirement!



Kevin

_________________
“Always do what you are afraid to do.”
R.W. Emerson (1803-1882)

"Real freedom is the sustained act of being an individual." WW - 2009

"Life is a good deal...it's worth it" Feb 1969
Dorothy McCune

Chris Lewis

Joined: 17 Mar 2006
Posts: 56
Location: Seattle

Posted: Fri Aug 22, 2008 11:39 am Post subject: Re: Elevator Authority

John - I also spotted these at the Hangar day event in June. Glad to see that your efforts are starting to pay off with the factory.    



I wonder if they will try them on a set of wings in the not too distant future...



Chris in Seattle

_________________
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vgstol(at)bigpond.net.au
Guest

Posted: Fri Aug 22, 2008 8:30 pm Post subject: Elevator Authority

Gday  Kevin,

 Yeh, I wouldn't go that far  to Oshkosh again.  I was disappointed in seeing only a couple  of homebuilt STOL type aircraft flying at the ultralight strip, where  you can get close enough to really judge the performance.....   Seemed like a really good opportunity for them to show off their action.   There was a session for two-seaters but not much used.....   

  

 I'm afraid that VGs in  themselves don't give fuel savings.  But other factors such as drag, speed,  and prop efficiency do.  So this testing has  nothing  to do with VGs,  just my curiosity and a passion for testing to get real  results.   And some day fuel might get really expensive, then  it'll be good to know how to get the best from it, especially for those of us  who fly a lot of x-country.

  

 Tailwinds  always,

 JG

  

 ---

eightyknots

Joined: 22 Aug 2008
Posts: 5
Location: New Zealand

Posted: Mon Sep 01, 2008 10:21 pm Post subject: Re: Elevator Authority

Hi John,



I was wondering about VGs. In a nutshell, what are the disadvantages of using them instead of slats?



I was always under the impression that VGs saved fuel (having no slats on a CH 701 must save a few kg in weight). What then are the advantages if it's not a fuel saving?

_________________
Hank

I am looking for a STOL high-wing plane to build, starting some time during 2009. Will it be an ICP Savannah, a Zenith CH-701, an Aeroprakt Foxbat/A22/Valor, or X-Air H?

John Bolding

Joined: 23 May 2006
Posts: 281

Posted: Tue Sep 02, 2008 3:59 am Post subject: Elevator Authority

Here is a good place to start, LOTS of real world testing. If you spend a 

little time doing some archive searching you will uncover an afternoon's 

worth of reading on the subject as it has been flogged to death many time 

here and on the combined list before the "Big Split".

Also LOTS of conversation on the subject on the yahoo group.



http://www.stolspeed.com/content.php



John





---

pdknight

Joined: 14 Aug 2008
Posts: 8

Posted: Wed Sep 03, 2008 2:49 pm Post subject: Re: Elevator Authority

Looking at some of the data and reports, I am half tempted to not even order the slats or install the slat mounts and going exclusively with the VGs.  I'm guessing this would save considerably on weight, and give a cleaner leading edge(not that it matters a whole lot in this airplane).  Thoughts?

jpspencer(at)cableone.net
Guest

Posted: Wed Sep 03, 2008 4:11 pm Post subject: Elevator Authority

>Looking at some of the data and reports, I am half  >tempted to not even order the

 	  Quote: 	
		  slats or install the slat mounts and  going exclusively with >the VGs.  I'm guessing

this would save  considerably on weight, and give a >cleaner leading edge(not

that it  matters a whole lot in this airplane).  Thoughts

  
	


 I removed my slats and weighed them. They weighed 13#.  They were also something of a pain to build. After flying with VGs for a while I  cut the slat brackets off and bondoed up the holes. I will sell my slats cheap  if there is anybody who wants them and is willing to pick them up in  Mississippi. There is no going back for me.

  

 Hope this helps.

  

 Joe

   [quote][b]

kenryan(at)alaska.net
Guest

Posted: Wed Sep 03, 2008 5:19 pm Post subject: Elevator Authority

You might want to read what Chris Heintz thinks:



http://www.zenithair.com/stolch801/design/slats-vs-vg-design.html



On 3 Sep 2008 at 15:49, pdknight wrote:



 	  Quote: 	
		   

 

 Looking at some of the data and reports, I am half tempted to not even order the slats or install the slat mounts and going exclusively with the VGs.  I'm guessing this would save considerably on weight, and give a cleaner leading edge(not that it matters a whole lot in this airplane).  Thoughts?

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p 2410#202410

kmccune

Joined: 22 Sep 2007
Posts: 577
Location: Wisconsin, USA

Posted: Wed Sep 03, 2008 5:21 pm Post subject: Re: Elevator Authority

I am starting on my wing build soon. I posted a reply to one of JGs comments recently. But the proof in in the pudding , so I am not building slats.  And I may build the wing long.



Kevin

pdknight

Joined: 14 Aug 2008
Posts: 8

Posted: Wed Sep 03, 2008 5:35 pm Post subject: Re: Elevator Authority

I see where he is coming from, and given my day job(I'm a c-17 pilot), I know firsthand the benefit slats provide.  Without them, the C-17 would have none of its short field capability.  

Chris Heintz is much more of an expert than I in the area of aerodynamics, but he is also a salesman, he has a business to run.  Slats provide him with revenue, and in a way are his trademark, so I am not discounting this as being some of the motivation behind the article.  I felt like the graphics he presented were quite elementary and gave no numbers of any kind regarding the performance, they merely had a picture with lines.  The stolspeed folks provide info, numbers, and proof of concept videos.  I'm going to do a bit more reading into the matter before making a final decision.  If I'm not happy, I'll slip into buyer's remorse as I unfasten the wing skins and install slat mounts...

PS:  I am in no way insulting the man who designed this fine aircraft I will soon be trusting my life with.

kmccune

Joined: 22 Sep 2007
Posts: 577
Location: Wisconsin, USA

Posted: Wed Sep 03, 2008 6:10 pm Post subject: Re: Elevator Authority

I have the utmost respect for Chris. And I believe that the slats provide the highest STOL performance possible with this aircraft. But I do not need to do dime size spot landings and give back change. I just need to land short so it will work for me and the fuel savings are an added benny.



Kevin

pdknight

Joined: 14 Aug 2008
Posts: 8

Posted: Wed Sep 03, 2008 6:27 pm Post subject: Re: Elevator Authority

Exactly.  I am willing to give up 10-15 feet of takeoff roll for ten extra mph in cruise and better fuel economy.  Even if the VGs had a slight negative impact on the STOL capabilities, it would still have extraordinary ability to get in and out of just about anywhere.

jpspencer(at)cableone.net
Guest

Posted: Thu Sep 04, 2008 5:04 am Post subject: Elevator authority

True. I can't measure any loss of STOL with the VGs. There  is no real world loss in my experience. I was able to duplicate JGs claims on  speed gains...but the real benefit is better low speed handling and same cruise  speed at reduced power/FUEL BURN...very big deal nowdays. The slats are IMO just  a marketing gimmick. They did work well on takeoff but I couldn't tell that they  were at all active on approach unless at a forced very high AOA. Add strut  fairings for an even more dramatic decrease in drag and you have a fairly  efficient airplane(with the Rotax). FWIW.

  

 Joe

  

  

 >Exactly.  I am willing to give up 10-15 feet of  takeoff roll for ten extra mph

 	  Quote: 	
		  in cruise and better fuel economy.   Even if the VGs had a slight negative impact

on the STOL capabilities, it  would still have extraordinary ability to get

in and out of just about  anywhere.


	


   [quote][b]

georgerace

Joined: 25 Oct 2006
Posts: 788
Location: Albion, MI

Posted: Sun Sep 07, 2008 6:15 am Post subject: Elevator Authority

First I am no expert, but the following just FYI and to think about



The Slat is actually considered as part of the wing surface and form.

Removing the slats and brackets will slightly change the lift of the wing

due to surface being lessened.  It will reduce weight slightly, and also

affect the Weight & Balance as it is measured as a percentage of MAC, from

the FRONT of the slat.



As I said, just something to think about from a not expert.



George

N73EX - Now Flying 



--

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