Sportsman STOL Equiped Airplanes

[Showboatsix]

How many of you out there are flying with a Sportsman STOL kit on their plane?

I installed one about four years ago on my 56' C-172, what I first noticed was the effectiveness of the ailerons at slow speeds, I mean indicated speed of 40 MPH. When I went out and did my test flights I used stock 172 handbook speeds, I climbed up to 3000 ft agl and then started to test the wing at slower and slower speeds. What I have learned is that at a full power 40 degrees of flap (climb prop) deck angle is in the 40 degree (estimated angle) zone with the wing buffeting, it will still shows 200 ft per minute rate of climb. At that deck angle you can do up to a 30 degree bank angle both left and right without losing a wing, the turn rate is like sitting in your computer chair and rotating in a circle. The indicated airspeed (although incorrect because of the angle of attack) is about 30 MPH.

Power off stalls are much different, 40 degrees of flap, slow down to 40 indicated, then decelerate slowly and you can bring the yoke back to the stop and hold it there, the nose is about a foot above the horizon, the rate of decent is between 650-700 ft per minute with the wings stable, now here is the good part, the airspeed is indicating about 35 MPH, roll in 30 degrees of bank..(left or right).. and again it is like you are sitting in your computer chair and rotating around it. If you do a 40 degree bank the wing still stays with you, but the elevator loses it's effectiveness and you can not hold the nose above the horizon.

Take offs are another thing, 20 degrees flaps, full power , stick back until the tail almost touches the ground, and she will claw into the air at an indicated 35 mph, accelerate to 45 best angle and she will show close to 1100 ft per minute (one up and 1/2 tanks) climb. You will break ground in about 300 ft.

Approaches to final are routinely done at an indicated speed of 40 MPH, the slowest GPS reading on final I have seen is 25 MPH ground speed.

The one thing I have noticed is that the taildragger 3 point, the tail is much higher than what I could get the C-172 tail on take off so my distance to rotate seems longer, more tests to follow.

Dean

[GAHorn]

What kind of takeoff field performance do you get?

[W.J.Langholz]

If you could also share your "56" C-172 performance also, I have a "57". What do you have for engine and prop? Grass field performance?

Thanks
Willie

[GAHorn]

...Take offs are another thing, 20 degrees flaps, full power , stick back until the tail almost touches the ground, and she will claw into the air at an indicated 35 mph, accelerate to 45 best angle and she will show close to 1100 ft per minute (one up and 1/2 tanks) climb. You will break ground in about 300 ft. ...

A standard airplane will do about the same under such light conditions if it's cool. The airspeed indications at such high angles of attack are unreliable. That's why it's difficult to assess whether the STOL mods are worth the expenditure, because comparisions are rarely made to any degree of accuracy. There's so much "perception" involved and so little accurate test-instrumentation.

I flew a 52 B-model using 20 degrees flaps, only myself aboard, and 1/4 tanks and it left the ground on a cool day and cleared 100' trees in 1100 feet from brake release. Ground roll was about 400'.

If an airplane already has a STOL kit installed and you like it, then it's probaby a good deal for what you get, but I doubt the expenditure, effort, etc. is worth it to convert an airplane unless it's a restoration project already. (All the models 170, in standard livery, will land in shorter distances than they can get back out of, and all of them will get out of remarkably short distances if they're kept very light.) It takes horsepower to truly make the airplane a short field performer, and an engine upgrade is an expensive proposition. It's usually better to locate/purchase one that's already converted.

[Showboatsix]

Well I can say this, I have close to 1500 hrs in this same aircraft as a tricycle geared plane, about 400 with the STOL kit, the wing, a standard C-170B or C-172 wing will fall out from under you if you try the same thing, if you do a full power stall and let her hang til it breaks and try a turn just before she breaks, you will end up on you back real quick! This wing will not do that!

When I get the taildragger paperwork finished in the next few days, anybody who wants to witness the wing can do so!

Dean

[170C]

These threads regarding STOL kits, etc. are always interesting to read. Its kind of like determining which airplane is the fastest. The only way (IMHO) to compare two planes, regardless if both are C-170's or a Cessna and a Piper or Luscomb, etc. Is to try to get the two planes at about the same weight, fly side-by-side and then advance the throttles to max rpm and see which one flys ahead of the other. Comparing rpm, temp, humidity, gross weight, mp and how someone feels on a particular day is a "guess" at best-------unless you are flying with me and in that case you WILL be faster than ole pokey Apparently no two planes are going to be exactly the same in every way. I have a STOL kit on my plane. It was there when I bought it and likely I wouldn't spend the time & $$ to install one myself, but some of the folks seem to find their planes performing better (or different) after spending the $$ to purchase & install them. Some day maybe somebody will be able to come up with some hard, reliable facts regarding how a particular airframe preformed under identical conditions before and after such an upgrade.

[hilltop170]

These threads regarding STOL kits, etc. are always interesting to read............ Some day maybe somebody will be able to come up with some hard, reliable facts regarding how a particular airframe preformed under identical conditions before and after such an upgrade.

Frank-
Since you asked, here is some cruise and max performance data I obtained from my C-180 under three different aircraft configurations; 1. stock airplane and engine, 2. stock airplane with upgraded horsepower Pponk O-470-50 (O-520) engine, and 3. after addition of Sportsman STOL, Wing-X wing extensions, and RMD wing tips. I'm no test pilot but I tried to duplicate the conditions as close as possible to minimize error.

I realize it's not a 170 however it is a Cessna wing similar to the 170. The graph is somewhat busy but it is evident the engine horsepower increase improved cruise performance 10-15mph and the Sportsman STOL plus wing extensions slowed cruise down 2-3mph. The plane had Cessna 206 drooped tips before and RMD drooped tips afterward so I consider that a wash.

For the slow speed end of the envelope I flew three different flight all with flaps up and the same configurations as the cruise charts: 1. stock plane/stock engine, 2. stock plane/upgraded horsepower, then 3. with the STOL kit/wing extensions installed.

I am also waiting to see some similar data before and after vortex generator installation on a Cessna wing. As far as I am concerned, the jury is still out on them until I see some real data.

Click on the graph to enlarge it.

N180RP_perf_chart_O-470_vs._O-520.jpg

N180RP Airspeed vs. power.jpg

[N171TD]

Just why would CESSNA use a cuff on their later year models if they did not help handling and performance ??

[GAHorn]

Just why would CESSNA use a cuff on their later year models if they did not help handling and performance ??

Because the "balked-landing-climb" requirement limited their desired gross weight increases, so they had to reduce flap extensions to make the thing climb, therefore in turn they had to do something to make it fly acceptably slow to make up for the reduced flap settings they were forced to accept. One bandaid after another to increase gross weights to make up for lost useful loads due to increased empty wts.

[N171TD]

Well guess you answered correctly -- makes the plane fly slower -- and I might add without slowing down cruise.
The cuffs were added to Cessnas after the Robertson was very highly accepted in the 70's.

[alaskan99669]

How many of you out there are flying with a Sportsman STOL kit on their plane?

Dean

Dean,

I put my Sportsman on last winter and the only test I did pre-install was glide ratio. I got 8.8:1 before the mod and 9.35:1 after. Far from the published 13:1 and I was really looking forward to the safety aspect of almost doubling the glide ratio using Sportsman advertised numbers. So that to me was a major let down. But I did finally get my floats on last week and it does appear to get off the water sooner now. Last year I was flying a moose out of a small lake 200 pounds at a time. It took 3 trips with minimal fuel (about 12 gallons), the wind was blowing a steady 15 MPH, and I was getting airborne in 1300' at 50 MPH indicated. Now full of fuel and a 150 pound passenger, a slight breeze, I'm getting off the water in 1200' at 40 MPH indicated. So it is a small improvement. It has noticeably better control in slow flight / high angle of attack so it's comforting knowing that feature is there should I ever find myself trying to clear those trees at the end of the lake, but of course the first step is to not get into that situation to begin with.

Going moose hunting again in 3 more weeks so will have plenty of testing opportunities then.

[mit]

Cory

Tell me more about that trailer/lift! Did you build it yourself?

[alaskan99669]

Tim,
A friend of mine built that trailer. I PM'd you his email address. He'll be more than happy to share the details with you.

[mit]

Thank you