I just completed the installation of a set of Horton Flap Gap Seals. The instructions were good, but set up was slow. The pop rivits provided were a real problem. The break point was very inconsistant. Four or five popped before the skins were made up properly and had to be re-done. I would suggest you buy your own if you use this product.
As for performance, I know there is a lot of opinions on this subject. Put me down in the pro catagory. I ran performance tests, taking data into the wind and and on reverse course at two altitudes before and after installation. There was a 10 deg C difference in temperature, colder on the after test so the data is not totally comparable. The difference in the calculated "no wind ground speed" was significant . More than I think you could attribute to the change in temperature. In fact is was enough higher that I want to do some additional testing on a warmer day before I quote numbers.
Finally I believe the performance was much better because I paid good money to make it so. The placebo effect is a strong one!!
So how much do they get for a set? I wonder how much extra speed could be obtained with these and strut fairings, brake lines faired, and such? I'm not keen on wheel pants so without them and using 6:00x6 tires and otherwise cleaned up do you suppose I could gain 5-8 MPH? With the new 180hp installation these things are a little more meaningful and beneficial.
The price was $236.00 with shipping which was about $10.00. I also got the aileron tape gap seals and that is included in this total. I have not installed the aileron tape yet as I wanted to get the performance separately for the gap seals.
This morning the winds were calm at the surface but the many steam stacks in our county indicated a slight wind aloft. So with a gross wt of 1682 lbs, temperature of 60 deg F, and barometer of 30.17 I ran my test loop again. I ran into the wind for 20 miles, using my home airport as a GPS reference then turned down wind for 20 miles. I did this at a density altitude of 1000 ft then 2000 ft. On the head wind legs I averaged 105 mph ground speed by the GPS distance vs. time. On the down wind legs I averaged 128. The “no wind” ground speed would be 116.5! My base case was 105 mph. I have done this on two consecutive days now.
No way am I suggesting that you can get a 10 percent increase as that does not seem logical to me. All I can say is that it seems like a significant change to me, enough that there is no question it is more than statistically significant improvement.
I forgot to mention the most difficult problem I had with the installation. Horton gives you pop rivets to attach the angle supports to the flap roller guides. After I had mounted two of them I tested the flaps and sure enough there was a major interference with the back side of the pop rivet which stuck out about 3/16 inches. My A&P suggested, and it worked well, that I replace the pop rivets with standard rivets where the back side or bucking side was counter sunk with a 100 deg bevel. Then when the rivets were driven in the flare from the bucking filled the counter sink and made a nice low to no protrusion finish on the back side.
I'm kinda in the dark on the flap-gap-seals. These are a speed mod,right? What do they do to the stall speed? And what do they do to low-speed handling at approach speed--1.2 or 1.3 times stall speed?
In my opinion,seems like unless you are gonna do a big-time aerodynamic clean-up--fairings on everything,modified baffling,custom wheel pants,bartone exhaust,plus coarse prop and/or big engine-- the results may not justify the time/money spent,especially if the TO/climb performance and low-speed handling are compromised. Of course,it depends on the "mission profile" for your particular kind of flying.
I have no experience with gap seals on a Cessna and there are a lot of things to consider with the fowler flaps but I can tell you that on my Cherokee the gap seals on the aileron and flaps made a significant difference in both lower stall speed, handling, and faster cruise of about 5mph. For the money I believe it is one of the cheaper mods for the performance gained. You are right about so many other mods available but the flap/aileron seals seem to be worth it on most airplanes and a good place to start.
Now there seems to be a question about our fowler flaps and whether sealing the gap actually decreases the effectiveness of the flap when deployed, negating the positive influence of the seal. For this reason I have not put them on my 170 yet but otherwise would installed them right after I bought the plane.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
I've heard others talk about a tape for sealing ailerons. Didn't know someone had a STC for a 170. Tell me more about it. What does just the seal tape cost? Can it be installed without the flap seal?
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
. More than I think you could attribute to the change in temperature. In fact is was enough higher that I want to do some additional testing on a warmer day before I quote numbers.
