The International Cessna^® 170 Association

Recently a friend in another country invited me to fly his 170a. we did about 2 hours in it and I observed all the relative engine and flight data, I openly and honestly remarked it flew very similar to mine . He then said lets land. After landing he then pulled a roll of duct tape[2.5 ins wide] from under the seat . He then applied the tape to to area wher the flap and wing was attached. He was masking up the gap. This was done to both sides. we then went flying again. I then re-observed all engine and flight data. At 2500 rpm ,airspeed was about 2 knots faster[a needle width faster on the ASI and confirmed by my ipad]. then he said lets land [we were still in the circuit]. With the flaps slowly extended at deceasing speeds IT appeared to be smoother and a little more controllable at the slower speeds.
I am not going to explain what I have done when I have got home but its interesting. Has any body done this ?? What would be the legalities of this application?

It is a gap seal made from tape and nothing new. There are some aircraft that have it from the factory today. There are STCs to apply it to Piper Cherokees for the flap and the elevator.

And the performance increase is about what is usually talked about.

Legal, to just do to your aircraft? Depends how the individual FAA inspector sees it but more probably wouldn't like it than those who wouldn't care. Technically it would be a unapproved change to the airframe which changes the aerodynamics.

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bigrenna wrote: am removing them as they are a detriment to the flaps on the slow end. Nothing is free.

Your 180 as well as 170Bs have semi Fowler "Para Flaps" which rely on air passing over the top of the flap which is why sealing this area reduces effectiveness. Though in truth the flaps are not sealed but the area beneath and in front is filled blocking air from passing over the flap when deployed. On these models the flap gap seal is only mean to increase airspeed by reducing drag.

'48 and A models don't have the semi Fowler flaps and therefor enjoy a benefit of sealing the flap gap regardless of it's position.

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