Flap Gap Seals

Bluebird

Bluebird

Filing Flight Plan
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Bluebird
Could someone share their experience with Flap Gap Seals? Did you really see 100-200 fpm better climb? 4-5 knots TAS? They look great and the theory looks sound, just like to hear from someone who has installed and/or flys with them. BTW I fly a 2005 Cessna, T18T. Thanks
 
Mine give me a few knots in cruise and about 50 fpm climb (PA-28-140/160). Roughly. I definitely noticed them missing and am glad they're back.
 
On a Cessna flap gap seals will improve performance when the flaps are up, however they diminish the effectiveness of the fowler flap when the flaps are lowered. I personally wouldn't have them fitted but I suppose if most of your flying is from long runways and are long cruises they may make more sense.
 
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83 182R

Did notice better speed, didn't notice faster climbs.

Did go looking for a reduction in flap effectivness expecting it to be there and couldn't find any. Short field T/Os and landings are the same as is dirty stall speed. I would suspect that there was a slight degreidation in the flap effectiveness but it is so small I can't find it.
 
Yeah, it works. They keep the pressure from under the wing from "leaking" to the top. You can also seal the aileron and elevator gaps with a piece of fabric glued to both surfaces. You just have to make sure you cut the strip wide enough so it doesn't catch tight at the ends of travel. I would do the flap seals in a different fashion from the ones that use the strip along the bottom. I would put a square neoprene seal twice the seals thickness from the aft edge of the cavity up in the wing. There it will create a small reduction in drag without any adverse effects.
 
Henning said:
Yeah, it works. They keep the pressure from under the wing from "leaking" to the top. You can also seal the aileron and elevator gaps with a piece of fabric glued to both surfaces. You just have to make sure you cut the strip wide enough so it doesn't catch tight at the ends of travel. I would do the flap seals in a different fashion from the ones that use the strip along the bottom. I would put a square neoprene seal twice the seals thickness from the aft edge of the cavity up in the wing. There it will create a small reduction in drag without any adverse effects.
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It's worth remembering that fowler flaps rely on slot effect, so reducing this air leaking through while the flaps are down will not be beneficial to their effectiveness. If I remember correctly, somewhere on the internet there is a forum thread talking about flap seals on Cessnas (probably a bush flying forum or something like that) where they discuss the downside of fitting them. May be worth Googling for it to see what information is on there.

I totally agree with installing aileron seals, apparently they can double 172 aileron authority at low speeds for relatively little cost.
 
We ran the numbers this year on a number of "speed mods" for the 182.

We decided the only one that might make sense was the "speed pants" and we weren't all that excited about that. We didn't pull the trigger on that, and probably won't.

Flap gap seals on a STOL bird, definitely seemed kinda silly.

The real "speed mod" for a 182 is a bigger engine. I would hazard a guess that this is true for most of the Cessna high-wing line. :) :) :)

We're kinda partial to the P.Ponk rebuild when the engine gets to the point we need to do that. There's faster stuff, and bigger engines, but they're significantly more expensive.
 
denverpilot said:
We ran the numbers this year on a number of "speed mods" for the 182.

We decided the only one that might make sense was the "speed pants" and we weren't all that excited about that. We didn't pull the trigger on that, and probably won't.

Flap gap seals on a STOL bird, definitely seemed kinda silly.

The real "speed mod" for a 182 is a bigger engine. I would hazard a guess that this is true for most of the Cessna high-wing line. :) :) :)

We're kinda partial to the P.Ponk rebuild when the engine gets to the point we need to do that. There's faster stuff, and bigger engines, but they're significantly more expensive.
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Flap gap seals only seal when the flaps are up. When the flaps are down, if you do the seal properly, you can actually improve airflow quality.
 
Yeah, but for 2-3 knots tops... it just seems like a headache not worth messing with.
 
denverpilot said:
Yeah, but for 2-3 knots tops... it just seems like a headache not worth messing with.
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Well, It also improves your flaps up climb to a greater degree than your speed, plus it saves you fuel in cruise. Do you spend more time in cruise or operating at the absolute bottom of the energy band? Not much really to mess up with them anyway. Strictly an efficiency measure the factory didn't institute as a cost saving measure.
 
Let's just say they're $500 to install... which probably isn't accurate, but...

It'd take a while in cruise to make back $500 at 2 additional knots of speed.

That's why we nixed it so far. If someone really got a wild hair up their butt to take the aircraft out of service for a week to mess with it (shops are always backed up around here, and stuff that'd normally take a single afternoon always takes a week)... I don't think the other co-owners would really complain.

Plus other more important stuff (like failed fuel bladder earlier this year) always seems to come up... so they're way waaaaaay down the priorities list.
 
ChrisS said:
It's worth remembering that fowler flaps rely on slot effect, so reducing this air leaking through while the flaps are down will not be beneficial to their effectiveness. If I remember correctly, somewhere on the internet there is a forum thread talking about flap seals on Cessnas (probably a bush flying forum or something like that) where they discuss the downside of fitting them. May be worth Googling for it to see what information is on there.

I totally agree with installing aileron seals, apparently they can double 172 aileron authority at low speeds for relatively little cost.
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FWIW I can still be down and stopped in under 500 feet with a little effort with flap gap seals:dunno:
 
Skylane81E said:
FWIW I can still be down and stopped in under 500 feet with a little effort with flap gap seals:dunno:
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Congratulations...:D....but it doesn't mean that your flaps are not less effective than without the seals.

I just found one thread discussing flap seals on Cessnas here.
 
ChrisS said:
Congratulations...:D....but it doesn't mean that your flaps are not less effective than without the seals.

I just found one thread discussing flap seals on Cessnas here.
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Didn't say they weren't, but I did say that even after looking for a degradation that I expected to find I didn't.

Would I put them on a bush plane? Probably not, but you don't need to confine yourself to "long" runways if you have them.
 
Skylane81E said:
Didn't say they weren't, but I did say that even after looking for a degradation that I expected to find I didn't.

Would I put them on a bush plane? Probably not, but you don't need to confine yourself to "long" runways if you have them.
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Not to be pedantic about the term 'long' but it does all depend on field altitude/DA, topography, etc. I'd guess that your 500ft landings are not at higher elevations. My choice is to have as effective flaps as I can possibly get, one reason I like flying my Cessna with it's fowlers, but then again I fly a reasonable time at higher altitudes and from relatively 'shorter' runways.
 
Not very high, no. About 3k on the DA is a typical summer day here. LXV wasn't any problem, but it's long and as I've never used short feild techniques there the gap seals probably helped as I had flaps up. Fact of the matter is like 90 odd percent of pilots 1200ft is a short strip for me. I mean lets face it I live in Ohio:rofl: for my mission they were a good buy:yesnod:
 
ChrisS said:
Congratulations...:D....but it doesn't mean that your flaps are not less effective than without the seals.

I just found one thread discussing flap seals on Cessnas here.
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Not all gap seals are created the same way. There is the metal/fiber/plastic brow plate that spans the gap and overlaps the flaps which has a negative effect on the gap airflow with flaps down, or you can use a sticky back foam block at the top back of the gap set forward 200% of the height of the block (measured at the trailing edge of the block) that seals the gap with the flap up. It's about 6% less effective at the highspeed end but it's also an improvement to the bottom end airflow compared to stock.
 
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