Horton Stol Performance

[Frank Benvin]

Just got our 1972 337F flying with Horton stol kit. Does anyone have a manual or can supply performance figures ( stall speeds ,flap settings for take off & landing etc) for horton kit

Thanks

Frank

[Mark Hislop]

Frank:

As far as I know, Horton does not supply a manual or any performance numbers. My plane came with a Horton kit installed, so I can't vouch first hand what the changes were. However, I find that my cruise speeds seem to match the book pretty closely, and my stall speeds seem to be about 5 to 8 mph less at all weights, as compared to the POH. Stalls are a non-event, but the nose is very high.

Mark

[Paul462]

Frank,

I just installed the Horton STOL kit as well as the VGs STC. The stall speeds have reduced around 5 MPH, and Vx appears to now be around 75 MPH instead of 86 MPH (determined experimentally).

Thus, for minimum take-off distance, rotation around 70 MPH and climb at 75 MPH appears to be the ticket, at least until obstacles are cleared. The reduction in take-off distance with the Horton STOL and VGs appears attributable to the slower take-off speed - it takes less time and distance to accelerate to 75 MPH than 86 MPH. These figures were derived experimentally, and are only applicable to my plane - your figures will doubtlessly be different.

Paul Rooy

[Frank Benvin]

Paul

Do you use the standard 1/3 flaps for take off???

Frank

[big al 08]

pull back and it waddles off around 60mph
1/3 flaps
excellerate very quickly to 90
stall around 50-55 (depending wt.)
no wind
with wind it's out of there now!

owen bell mod
american enterprises

[Paul462]

Frank,

Yeah, I've been using 1/3 flaps thus far - haven't tried no flaps, but I imagine take-off would take longer with no flaps.

Paul Rooy

[hharney]

I have the Horton system on mine and have been using it for 30 years. Best mod for any money you can spend on a 337. All 337's should have the conversion.

For T/O I use the book 1/3 unless I am asking the airplane for a performance short take off and then you should use the same amount of flaps as full aileron deflection.

[Skymaster337B]

The Horton STC does state what the limitations are: Simply stated, it will meet or exceed the Cessna numbers and that you should go out and experiment with it to determine the actual numbers. So in otherwords, just use the Cessna book and you'll be happy that it does better.

From my experience the airplane will not stall with a Horton kit, just mush and gently hold the nose below critical angle of attack; my guess is the elevator is losing lift before the HORTON wing is, which is how tricical type airplanes should be.

[cfc1234]

Is there no flight manual supplement with the Horton Kit Installed?

[cessnadriver]

Cfc1234.
The answer is "NO". As another poster stated the Horton has the pilot determine speeds with experimentation. I talked to one of the original engineers at Horton and he gave me that information as well. Nice old guy that talked about how the owner of the STC was tight with the local FSDO and that's why they didn't have to do the flight tests that Robertson had to do? As for one of the posters said it's almost impossible to stall the skymaster. It's true, during my rating check ride I had to fly my bird at around 65 mph with no stall warning horn, no problems. As many Skymaster owner can contest that the tail stalls/shudders in stead of the wing as with most other Cessnas. Hope this helps.
Regards, BILLS

[cfc1234]

Does anyone on here have a copy of the STC by chance? Is there a "partial install" of a Horton Kit? What all is included in a full install?

[hharney]

1. Leading Edge Cuff
2. Stall Fence
3. VG's on rear cowl
4. Boom to Vertical Cuff
5. Wing Tips (various extremes)

The only item that I have seen partially done is the wing tips. Use the factory Cessna tips or buy the Droop tips from Horton

[cessnadriver]

Hello ALL.
I threaded this before about the wing tips for the skymaster. I didn't like the SUPER droops, the ones that extend about 18" below the bottom of the wing, that came with the Horton kit. I ended up talking to one of the original engineers from Horton, and he told me that you HAVE TO HAVE some amount of droop on the tips. So I sent him pictures of the tips I purchased from a SOAPA member. It looks like single engine Cessna tip, that droops about 4" from the bottom of the wing. He told me that would be fine! He also sent me a blue print of the kit showing a less severe tip with Cessna part numbers.The plane flys fine with these tips and make OUR Skymasters look better than those ugly super droops.
Hope this helps.
BILLS