Horton STOL conversion

[Rickskymaster]

Does anyone have experience with the Horton STOL conversion?

Can you tell me how much it lowers your stall speed and how short of runway would would feel comfortable going into after installation.

Does it increase your gross weight and/or useful load.

What airpspeed do you use on short final vs before.

Anything else that would be useful.

Most important, was it worth and expense?

Rick Galvin
N48AT

[Mitch Taylor]

Rick: Try searching the site. I think that this has come up before, although I don't think all of your questions are answered, it would be a start.

Mitch

[Rickskymaster]

I went out and did a search, the web sites are there, but nothing else that was of much use.
If you have Horton's set-up, I would be very interested in hearing your thoughts.
Rick

[MikeZ]

Been flying 14 years with a Horton Stol. In the air I can fly level at about 45 KIAS. I approach at normal speed, and flare at about 70 kts. The real benefit I find is in the margin of safety. I would comfortably fly in and out of a 2000 ft. strip (not at night). The Horton kit is far less expensive than R-stol and almost as effective, although I have no personal experience with the latter. mike z

[Bob Cook]

Rick

Really depends on your mission profile. If you are using short fields most of the time -- yes there is a benefit.

If you are running full gross with normally aspirated engines at higher elevations. --- yes, they can be beneficial.

They are a problem to install with boots. There is added expense.

They can get you into as much trouble without since when you try and push the envelope.

In my opinion they are not worth it unless you have a specific purpose and need them. Again, application dependent.

I expect there is a couple of knots loss in Air speed.

Perhaps there are others that can add their two cents worth....

fyi

bob

[Mark Hislop]

Rick:

There was a Horton STOL kit on my 73 P337 when I got it. I can't give you "before and after" figures, since it was already on. But I can tell you that my stalling speeds are about 5-8 mph lower than the POH figures, my cruise speeds are about the same as the POH, stalls are very clean and gentle. Slow flight is easy and the controls don't feel mushy. I don't fly in and out of short strips, but I do a lot of flying in the pattern with 172's, Luscombes, and other "slowpokes" and I can for the most part fit in with them.

I don't use the STOL capability to it's full extent on landing, because I don't like the attitude...I'm looking up at the sky and it's hard to see the runway.

There are no published figures or changes to the POH with the Horton kit. I believe the Robertson STOL does give you published lower figures. The Robertson is quite a bit more complex, as it links the ailerons to the flaps. It is quite a bit more effective, but also three times as expensive.

The Horton does not increase your gross weight.

All in all, I like mine.

There is also a vortex generator application available for 337's now from Micro Aerodynamics. One of the normally aspirated 337's on our field just had them applied, and hesays he is getting about the same performance improvements that I have. Their literature claims a 15% reduction in stall speeds at 0 flaps, 9% reduction at 1/3 flaps, and 8% reduction at full flaps.

If your interested, you can probably get more info from Micro Aerodynamics. Their phone number is 847-364-6688. The price of the VG's is $1950.

Mark

[Bob Cook]

Mark

Great info. The VG's make a lot of sense. I wasn't aware someone took the time and effort to plot them out! VMC rollowovers are rather non existant in the accident history files, however, anything to improve the low speed performance is an improvement.

My understanding is the Horton does reduce aileron authority at lower speeds and does increase the angle of attack during approach as noted by you.

I think the Robertson system tried to correct this problem using a more complex approach.

Perhaps the VC'smake a good cost effective solution.......

Bob

Both the Horton and the VG kits were on my plane (337A) when I bought it. I thought that the VG kit was part of the Horton kit, but am not sure.

My stall speed at landing is about 7-8 mph below POH, and the thing flies as firm as a truck. The cruise speed is about 3-5 mph slower than POH, but that is without having things tightened up as much as possible.

Keven
________
Vermont dispensaries

[Dave Underwood]

The Micro kit sounds good. Does anyone have any current experience with installing it and the resulting performance changes?

regards - Dave

[Mark Hislop]

Keven:

I don't know if you had the VG kits I'm referring to. It is my understanding that they have just come out.

The Horton kit has some VG's installed on the lower rear engine cowling. The Micro VG's are installed on the wings, and the rudders. I think there are something like 92 VG's in this installation.

Mark

Mark:

You're right. My VGs are on the rear cowling only.

Keven
________
Ford Model T History

[Bob Cook]

VG's are the way to go!

Installation is best done when repainting the aircraft. VG's have made considerable improvements on handling with other AC. It is the most ecenomical method of gaining performance without major changes.

The airflow changes with angle of attach. Keeping the boundary layer intact keeps the AC flying.....

Bob

[Dave Underwood]

VG are very interesting.

Check out the web site: www.microaero.com

They do appear to be new for the 337 which is why I was asking if there was anyone with some real life experience with this kit.

From their web site, they mount 92 VG's on the wing, 76 on the rudders and 40 on the uinderside of the horizontal stab.

At a cost of $2 k, that is less than $10 each including all the glue etc. Not bad.

Who is going to be the first to get them installed and let us know how they managed with the 337 paperwork.

[Mark Hislop]

There is a 337 on my field that already had them put on. I'll see him this weekend and find out what hoops he had to jump through. I don't think it was too bad.

Mark

[Jose L. Ichaso]

I had a copy of an old performance chart from Horton for the Skymaster, think was included in one Sky Smith's "Skymaster Newsletter", and claim 100 lbs MTOW for a 337D to 4500 lbs, and three diferent approach speeds and distances for landing and takeoff, labeled as "normal", "Stol", and "max performance Stol", the last one was 55mph!. Think was published for a while, before leaving the pilot to push the envelope for himself. The kit is very usefull for very short runways, which I use quite often.