I have read most of the Zenith forums and blogs but have only seen a short mention of stall fences on a 701 or a 750. I am curious if anyone has installed stall fences and what were the results.

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Victor,

Bob Jones has installed 3 fences on each wing and likes it. On this video you can see them at 2:00 and 3:45.

https://www.youtube.com/watch?v=KgW2nJwPTKg

Wait for him to give more details.

Think of these stall fences as .025" (or thicker) 20 mm flange angles that are formed into curve matching wing top skin, installed between wing ribs to reduce or get rid of oilcanning. I also think of putting angles on top of the horizontal stabilizer between ribs for the same purpose.

Champ

Hi Champ:

Stumbled upon your post.  I too have added angles on the elevator and rudder to tame expected oil canning. The new horizontal stab built to a conventional profile from scratch has .025 skin and wont oil can. As well there are extra angles inside the fuselage to reduce oil canning.

Question:

It has been said that Pega-Stol wings reduce stall speed over the stock 750 wings?  Is this true and if so, why?

Are these wings still being manufactured? I assume they would simply bolt up?

Thanks as always,  Brian

Perhaps a greater wing area? Your thoughts would be appreciated.

Thanks Champ, I can see how this could be helpful to stop oilcannining, but I wonder if anyone has done airflow testing to see the effects of the stall fences on the 701 wing. I recently purchased a 1997 Zenith 701 with PegaStol wings. I am flying it on wheels now and will have it on floats this Summer. It is pretty well stock from 1997, so I plan to do a major restoration, including mods, this winter. Just gathering information at this point.

Have you checked the Forum on Zenair Floats? There must be quite a number of CH701 seaplanes as well as amphibians.

You are lucky to get a rare item!

I went to New Zealand once to see a CH701 with PegaStol wings. The owner flew it with Jabiru 3300. The wings look simple enough and I started drafting up my moving slat wings. Then I saw the pivoting slats at supercub dot com and it seemed the swing slat wings could be built easier and lighter at less cost. I am rebuilding the wings with wing spar tip 510mm longer than standard and not quite half way in modifying the way slats are fixed to the wings. Flight testing date remains unspecified.

Champ

Yes it is a rare find. If you Google PegaStol it is the aircraft flown on their video (FZTS) The nameplate actually reads PegaStol rather than Zenith 701 and it didn't come with drawings or a Zenith serial number. I have purchased drawings so now I have a serial number and am able to purchase parts. I only have about 20 hours on it so I am still experimenting. I fly a Cessna 182 with a Robertson STOL kit which incorporates Stall Fences. That is why I am asking question about fences.

Hi Victor,

I have installed Stall fences on my CH701sp main wing. Two of them on both wings. They are located at each end of the wing using the most inner and most outer Slats brackets. They are made of 0.040 aluminum and about 1.25 inch high.

Some pictures are in my photos from this site.

How do they perform ? Well, not much change from having none. Maybe a slight improvement in steep turn (less rudder) and more straight turns... Otherwise, in normal flight nothing good/bad. I haven't flown them extensively so far...

Guess that on floats, at low speed in steep turns they would help somewhat to keep the plane from wandering...

Regards,

Norm

CH701sp

Hi Normand
Thanks for your response. Did you do any ribbon airflow testing before and after installing your Stall Fences? I am curious whether the airflow starts moving diagonal along the wing in slow flight or when approaching a stall. I am away from my plane for another 3 weeks, but plan on mounting a camera and doing some test flights when I return.

Hi Victor,

No, I haven't done any test for airflow with/without wing fences. I had the Slats off and VGs installed before I could do any of that stuff. If you check Stolspeed website you can see some of the tests they did...

I haven't flown my 701 much since I installed the wing fences but initial flights didn't show much of anything either good/bad. Mind you, I dont fly in Extreme conditions where all that stuff would most probably make a big difference.

Regards,

Norm

I saw the airflow tests for beanie mods, which gave me the idea that someone might have done testing for fences.
I will do testing in a few weeks and post the results.
Thanks to all for your help.
I have the PegaStol wings, so fences may not react exactly the same on fixed slats or vg's but I will post my results.
I have learned so much from everyone on this forum, that I hope to contribute something back.

  Saw an older video of Zenith 701's from France. They had a V shaped stall fence located on top of fuselage,  just behind the rear attach points of the wings. my thoughts were that this would encourage airflow to spill down the sides and control turbulence...

RSS

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