Trailing Edge Fences.......WOW

[av-mech]

I had not found time to install the TE fences until this week.  I have flown my VEZ 57 hours since early July and was getting used to how it handled (and did not handle).  After a little scare going into Orlando Exec last week and running out of left aileron during a direct crosswind I decided to get it done. 

I flew them this morning on a group flight to X60 for some lunch.  WOW is all I can say.  Those fences changed my approach and landing speeds by 10 kts, no kidding.  I went from coming over the fence at 75 kts to something closer to 65 and the solid feeling the ailerons had all the way to touchdown was something I had not had previously.  Big difference, no wonder people who have them love them.  I had no decrease in top speed (currently about 170 mph) and I did not really sense that the ailerons were any different at top speed but I did notice that I had to run a little more nose down trim.  This may be a fluke but it also seemed like the prop noise went down a bit.  I can't really put my finger on that one but it was quiter in the cockpit than before the fences.

[verieze1]

Would it be possible to get a picture or two of your TE Fences?

[F-PCGG]

Did someone test these trailing edeg fences on a Long Ez.
Is the efficiency the same as for VZ?

Gérard

[GlennBob]

Lot's of  Longez's out there with TE fences on them.

Glennbob

[BruceHughes]

NO, the efficiency is not the same because the wings of the Varieze slant backward
more.  Originally Burt said there was no noticeable effect on the Longeze.   Later he
decided to recommend trailing edge fences.  But they don't help (I am guessing
as my project has never flown) as much.

Bruce Hughes
Microbiologist
Knows very little about aerodynamics or building   

[Joe Person]

Vortilons (leading edge) were made mandatory for the Long-EZ, when equipped with the Roncz canard, as detailed in CP 46.  Vortilons were also identified for the VariEze, in place of the earlier-designed leading edge cuff.  Vortex generators were discussed in CP 66 (thereabouts) for the GU canard.  Trailing edge fences were never identified for use on a Long-EZ in any of the Canard Pusher newsletters.

[av-mech]

Joe,

I think, based on my recent research on the subject that the TE fences became known as mandatory on Long's because Klaus had said as much.  I know that I have read commentary on his messing about with them on a long and saying "yes" to them.  At the moment I cannont quote/remember my source but will keep looking.  Having read many of the CP's lately I have not seen them listed as required equipment on the Long's.  As most of us are aware, if Klaus is doing it it's probably a good idea.

[Joe Person]

Some have seen some improvement with low-speed aileron authority on the Long-EZ, with a fence installed on the wing TE just outboard of the outboard end of the aileron.  A former hangarmate put fences on in 2 or 3 locations on each wing, with little discernable change in characteristics.  I was just puzzling as to where Burt indicated that Long-EZs should have TE fences.  No reference to them is made in any of the CPs.

[easyrider]

I have trailing edge fences on my LongEZ. I have been flying 5+ years with them.
They are fitted just outboard of the ailerons as describe in Joe Person's post.
When I fitted them I noticed a signifant improvement in aileron control during final approach.
Starship has trailing edge fences
Easyrider

[av-mech]

Just out of shear curiosity, any idea what the LE/TE sweep angle is on the starship as compared to the Long or Vari? 

[av-mech]

Finally getting around to posting pictures of my TE fences.  Still need to run a fine brush around the joint and get some white paint in there.  The little black spots you see on the wing surface is bug/spider poop.  I wipe those off everyday and the next morning there's more......drives me nuts.

I think, after some research I am going to pull off my standard vortilons and make more of a fence that covers both the top and bottom wing surface.  Somthing like you see on the LE of a T-45, much more like the shape of the letter "C" that extends back a couple of inches from the LE.

[av-mech]

http://www.b2streamlines.com/WingFences.pdf

Using this information to design my new LE "potential fences"

[go ez]

Burt used pretty large trailing edge wing fences when he was developing the prototype Long Ez N79RA for the heavier MTOW, O-235 engine and lower landing speeds he (or rather more like the builders!) desired.

I recall seeing a picture of it at Oshkosh - still with wing cuffs (which preceded the vortilons)  and the VE wing. Note the (ineffective) rhino rudder up front and no winglet rudders and no lower wing skegs (I can't bring myself to call them lower winglets) !!!!

http://cdn-www.airliners.net/aviation-photos/middle/6/3/3/0773336.jpg

Originally Burt wanted to use the VE wing for the LE by using a longer spar. Eventually after about 50 iterations he realised he just couldn't make the VE wing work within the dedired design requirements, so he designed a complete new wing & airfoil section, similar to that of the Defiant. An innovator like Burt is likely to have tried almost everything. Once the Long Ez came out, sadly his development of the VE broadly ceased (other than mainly reactive responses to safety issues).

Due to the work of others like Klaus, the VE wing performance/capability now is very different to that which existed when it was first developed and from the performance data (presumably including wing  cuffs since they were mentioned in the text ) shown in the final 1979 3rd edition of the VE pilot's handbook.

I have standard vortilons and 3 main wing fences per side on my VE (exactly as per both av-mech's photos and Gary Hertzler's) and they are just fantastic. Aircraft is much better and solid at minimum speed, has better aileron response, better control at lower landing speeds and far better visibility on approach at those lower speeds.

Regards
Steve

[av-mech]

Steve,

That's a great post, full of good useful information, just what I like....  Did you look at the link I posted regarding the leading edge fences?  I am going to try a more aggressive fence if for no other reason that just to try it.  I am happy with my landing speeds now, just flew this morning and was touching down about 66-67 kts with full control.  I still think the ailerons are not as powerful as they could be though.  Despite having the fences both front and back, I can still run out of aileron in a moderate Xwind.

[go ez]

Thanks - appreciated. Yes I read that - very interesting - be interesting too if there is a deminishing return as the fences get bigger & perhaps increased drag effects inc. criticality for ensuring they are in line with the airflow.

Steve