Horton STOL conversion
 

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

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

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

Good thing that Horton Stol
 

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

horton stall
 

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

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

VG's
 

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

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

regards - Dave

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

re VG's
 

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

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. :)

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

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.

I HAVE THE HORTON KIT ON MY C MODEL NORMAL ASPIRATED. I FLEW BEFORE IT WAS INSTALLED AND I WOULD HAVE TO SAY THAT IT IS THE BEST MONEY I HAVE SPENT. I WOULD SUGGEST IT FOR ANY 337 NO MATTER IF YOU WERE FLYING FOR THE SO CALLED APPLICATIONS OR NOT. IT JUST FLAT IMPROVES THE HANDLING AND THE PERFORMANCE OF THE AIRCRAFT. PUT IT ON AND FOR GET IT IS THERE OR USE IT FOR THE TIMES YOU NEED IT. THERE IS NO REDUCTION IN CRUISE SPEED.

I FLEW FOR 18 YEARS IN THE HIGH DESERT AND IN AND OUT OF A LOT OF SHORT, HIGH, UNIMPROVED FIELDS AND IT MAKES A HUGE DIFFERENCE. HAD A 172 THAT WE PUT ONE ON AND IT REALLY CHANGED THE AIRPLANE. MADE IT MUCH SAFER AND EASIER TO FLY SLOW, IN AND OUT SHORT, AND DID NOT EFFECT THE CRUISE PERFORMANCE.

I THINK IT'S A NO BRAINER FOR MOST AIRCRAFT.

VG's

Talked to a mechanic about VG's. His comments are
they are only glued on and there is a chance of loosing them. If a bunch go missing it will affect the areodynamics. Other concern was flying into ice and having them collect ice. How will it affect the aircraft performance. Any one have any experiance or comments

Frank

The Scoop on VG's
 

As promised, I asked a guy with a normally aspirated 337 at our airport about his VG installation. He installed the Micro Aerodynamic VG's about 2 weeks ago.

He was very impressed with the VG kit. It came with a laser cut tape that is layed out on the wings, and the VG's are glued in place. The VG's came pre-painted to match his paint (I think this costs $100 extra). He said the kit was very complete, even included some bandaids in case he cut himself working on the VG's.

The VG's are supposed to be able to be installed in a day. He said it took 2 days for his to be installed.

The VG are very small (maybe 3/4" long and 1/4" high), not like the big ones installed under the rear cowl on my Horton kit. If one did come loose, I don't think it would hit the rear prop, and if it did, I can't see how it could do much damage. I've seen these on other twin Cessnas over the years, and I've never seen a missing one.

This guy hasn't fully checked out the performance improvements yet, but says that his initial reaction is that full flap stall speed is lowered by about 6-8 mph (about the same as my Horton kit provides, but at about half the price.)

Mark

vg's
 

Frank

I would disagree with your mechanic

"a bunch go missing it will affect the areodynamics". These are put on with superglue or epoxy. Chances of losing them are minimal. Considering the qty I rather doubt it any loss of performance would be noticed.

"Other concern was flying into ice and having them collect ice"

Ice collects on leading edges or behind leading edges creating ridges; not near the chord of the wing or behind the chord. These "gates" (VG's) are designed to keep the airflow attached to the wing. I would expect during icing conditions the pilot would increase manouvering, approach and landing speeds accordingly with or without VG's ! With ice all theory goes out the window.......

Technology has come a long way especially in the layout and implementation of VG systems. Hard to find any modern aircraft design not using VG's ...... somewhere.

I am sure there are no limitiations on the STC.......

The only real difference between the Robertson and use of VG is the aileron authority and the # of sq ft of additional wing or flap area (to keep it simple).

Slow speed........... go get a helio courier (amazing) then do a turbine conversion with a 5 blade prop <G>.

Finally...... how many fly 6 knots below published airspeed with a horton system or any other ??????

Bob

I've owned two skymasters. Both with Horton STOL kits. Flown one skymaster without. I notice final approach is steeper than normal. Stall speed with full flaps is 52 MPH in my skymaster. I take my final @ 80-85 and flare 65-75. Works for me.

Micro Aero's VG's
 

Hi guys, when I inquired at Micro Aero about the VG's here is the response that I received, there were some on the old 727. Guy, the old 72 driver.

Guy: Boots and VGs work well together. In fact, the STC certification
airplane had boots, a model T337H. Picture of that airplane is attached.

FAA DER Test Pilot said that what he liked best about the VGs on the 337 is
that with the VGs the airplane told you what it was going to do in stalls
and other maneuvers. We put VGs on Bobby Unsers Aztec and he told us about
flying off of his airport at 7600' with 2300 feet of grass. He said, "Before
VGs I had to beg the Aztec off of the runway and with VGs it jumps off." So
when you install VGs on your 337 you should look for that improved
performance at altitude.

Instrument instructors tell us that with VGs the airplane is a more stable
instrument platform. And we have had many reports saying the find a
smoother ride in tubulence.

Kit is very complete and takes a day to install. With your order I need to
have serial number, N-number, shipping address. Any credit card and we ship
same day.

Let me know if you need more info and let me know when I can ship you a
Micro VG Kit for your 337.

Charles White