Horton STOL performance

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Re: Horton STOL performance

Postby bagarre » Sun Jul 17, 2016 12:10 pm

While you're checking, verify you have an entry for rebalancing the control surfaces after being painted.
Your opening post stated that you were a partial owner and have already flown the aircraft.
How did you do that? As an owner operator, it's your responsibility to ensure the aircraft is airworthy. You didn't verify all modifications were safe and legal before operating that aircraft?
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Re: Horton STOL performance

Postby flyingredyeti » Sun Jul 17, 2016 1:17 pm

In fact I did check the STCs, ADs, 337s, and logs before flying it David. The fact that I overlooked the strut fairings simply illustrates that I am new to the 170, and is the first piece of useful information you have provided in any of your responses to my posts. So, thanks for that tidbit.
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Re: Horton STOL performance

Postby b_raby » Mon Jul 18, 2016 7:20 am

For the record, let me state I am not an engineer, I only have a high school education. What I am going to say about a speed increase with a STOL kit is based on my experience with my airplane! I have a 1954 Cessna/Avcon 170B (180 hp/constantspeed prop) with a Sportsman STOL kit (S/SK). The Avcon engine conversion was installed on the airplane before I purchased it. I replaced the original Pitot tube with a heated Pitot tube; later on I had the S/SK installed. The air plane has wing strut cuffs and (Streamliner) wheel pants with brake caliper fairings. The cruising power setting I used, before installing the S/SK was; 2400 RPM and 24 inches manifold pressure (24 sq). I would normally set this up at about 3000 ft MSL and higher and when the trip would be more than 30 minutes long. My ASI has a true AS setting ring (to set the ring to the altimeter setting and the outside air temp). Now remember, our ASI markings are in 5 mph increments (at least mine is)!
With this power setting, 24 sq; the ASI setup for true a/s (before the S/SK was installed). The indicated true A/S was 138 mph (the ASI hand was setting haft way between; 135 and 140 mph, I rounded it up from 137.5!). I remember this because I was always being asked; “what kind-a cruising speed do you get with that 180 hp engine”?
After the S/SK was installed with the same power setting and ASI set up; the indicated true air speed is 140 MPH (120 KTS). It has never changed, I’ll be glad to take anyone up so you can see for yourself (I have not had my ASI calibrated, but that would not change the fact the ASI changed 2 MPH). There was one thing I did noticed after the S/SK was installed; when I setup the 24 sq. power setting and with it all “trimmed” out in cruising speed; I could really notice the it was setting “on the Step.”
Like Frank, I had always heard that there would be a slight loss of speed after installing a STOL kit. Based on my experience, I can only say that did not happen in my case.
If you look at an earlier response with the out-lines of the profiles of the original wing cuff and all the add-on STOL kits, you will see the S/SK protrudes out the farthest. My rough measurement is 2 inches farther. Those 2 inches adds to the lifting surface of the wings. I believe that added lifting surface changes the drag coefficient and gives a slight increase in speed (with the same power setting, etc.).

I just read the sales article for the Sportsman STOL kit from another earlier response. It’s true, it will eliminate the “Classic” stall, instead of “Breaking” into a stall, it just mush down then start flying again or if you don’t push the wheel forward some, it will mush again, etc..

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Re: Horton STOL performance

Postby N8293A » Mon Jul 18, 2016 3:18 pm

Byrd I have to agree with your findings. I have the Avcon conversion and the Bush STOL kit on my a/c. I have owned the airplane 18 years, and have flown it from Alaska to Florida and Colorado to West Virginia and everywhere in between. Using gps data I have concluded it cruises at 120 kts at 24 squared. I have no scientific data to prove this fact, just my real world experience over the years.
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Re: Horton STOL performance

Postby GAHorn » Wed Aug 03, 2016 12:07 am

bagarre wrote:[...What's your basis of approval for those strut fairings on your 170?
I'm curious if there is an STC for those or if you had to get a 337 field approval as they are not original to the aircraft.


bagarre wrote:While you're checking, verify you have an entry for rebalancing the control surfaces after being painted.
Your opening post stated that you were a partial owner and have already flown the aircraft.
How did you do that? As an owner operator, it's your responsibility to ensure the aircraft is airworthy. You didn't verify all modifications were safe and legal before operating that aircraft?


When I read that post it struck me as being a bit overly critical on detail, and accusatory... basically un-friendly. I hope that wasn't the intent.

It's my belief the wing strut cuffs do not rise to the description of a major alteration, and therefore as a minor alteration only require a logbook entry by an A&P. No big deal. (unless you're an originality nut, in which case they are totally ILLEGAL!) :twisted:
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Re: Horton STOL performance

Postby flyingredyeti » Fri Apr 28, 2017 9:23 am

Follow up to the start of this thread: After spending 30+ hours flying this bird, practicing stalls, slow flight, and short field landings, I can confirm that the airspeed indicator will in fact bottom out before she eases into a gentle stall. I've landed her as slow as 42mph in a slight crosswind without much effort at all, and she'll take off from 439'msl at 50 degrees Fahrenheit, loaded to gross weight, in less than 500'- again with very little effort. She cruises at 130mph under 75% power, reinforced by the GPS, but I have yet to compare speeds at slow flight to the GPS- that will be curious. While the indication of 0mph before a stall is obviously an indication error, I do no believe the landings at 38mph IAS, or slow flight at 40mph IAS are too far off, as the nose of the bird is not all that high.

As to the STOL kit installed, the paperwork reveals it to be a Mid America STOL conversion.

I'm still getting to know this airplane, but I can state with some authority that she flies excellently.

Heh, can you tell I'm twitterpated?
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Re: Horton STOL performance

Postby FlyingSetter » Fri Oct 18, 2019 12:49 am

Does anyone have any information related to best glide speed and glide ratio for a 170A with the Horton STOL kit?
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