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Flaps for PA12 short or long

twoton

Registered User
Dassel, MN
I'm in the process of a complete rebuild for my PA12 and am putting on PA18 flaps. The original had PA14 flaps but the paper work described PA18 flaps. As most may know PA14 flaps are 65" and come up to the end of the wing. PA18 are 62.5" and would require a 3" fairing. My question is, since I'm building the flaps should I stay with the standard PA18 at 62.5" or build them as extended PA18 at 65". I would appreciate comments on possible tail flutter with the wider flaps.
 
If I was at the complete rebuild stage I would go with the wider flaps, unless somebody could make a technical case against them. I haven't heard of a tail flutter issue (but that doesn't mean its impossible). A friend of mine has the '14 flaps on his and they work great. What else are you doing, mod-wise?
 
Pretty much all the typical mods. I have a new Dakota Airframe fuselage with increase gross weight, along with extended upper and lower baggage. Seaplane doors on both sides. Out front is a 160 hp with a borer prop and Sutton exhaust. Extended PA18 gear and PA18 tail feathers. All new Dakota ribs and spares.
 
twoton said:
Pretty much all the typical mods. I have a new Dakota Airframe fuselage with increase gross weight, along with extended upper and lower baggage. Seaplane doors on both sides. Out front is a 160 hp with a borer prop and Sutton exhaust. Extended PA18 gear and PA18 tail feathers. All new Dakota ribs and spares.

I would probably just go with the flaps you have the paperwork for, that would be the driving decision in my case.

Tim
 
pa-12 flaps

Use the 62.5 in. pa-18 flap as the 3in. between the flap end and fuselage is to let air through to the tail for flair . I built a pa-12 using the long flaps all the way to the fuselage and you would run out of elevator on flair.
 
I was interested to read Dwight's experience (above): the flaps on my -12 go right up against the fuselage, and I have never run out of elevator regardless of loading. Maybe some time Dwight and I can put our planes side by side to see if we can explain the difference in performance.

Eric
 
If you are a running an 0320 you are supposed to run PA18 tailfeathers My flaps are inboarded and have Never run out of elevator. V.G.'s help alot if you still have that problem with PA18 tail. Check up & down elevator for Proper Deflections 27 deg up & 32 deg down
 
Re: pa-12 flaps

dwight russell46 said:
Use the 62.5 in. pa-18 flap as the 3in. between the flap end and fuselage is to let air through to the tail for flair . I built a pa-12 using the long flaps all the way to the fuselage and you would run out of elevator on flair.
--- I BELIEVE applying flaps creates downthrust on the elevator/horizontal stabilizer assembly which increases effectiveness. I know when you apply flaps you are greatly increasing the wings incidence angle relative to the tail. This is the same basic thing as applying UP elevator. Also notice how much less back stick pressure is needed to flare with full flaps as compared to no flaps. I don't buy the 3" air gap argument. If anything its backwards. I think that particular '12 ran out of elevator because it either didn't have a balanced tail ('18 style) and/or was nose heavy -- not uncommon on a modified '12.
 
I have a lot of time (over a 1000 hr.) in '12s with every configuration, ie no flaps, standard 62.25", inboard ext. and 8' flaps.

1. ext. inboard does very little on a '12 because of the window profile when deployed full. Unlike the '18 that can be squared off a total of 3" it only acts as a gap seal.

2. By far the very best mod on a '12-'14 is Ron Sullivan's Night and Day conversion. which allows for an 8' flap with the aileron moved outboard. Very impressive

3. If you have flown much in a '12 without flaps, you will think you died and went to heaven with the standard 62.25" flap.

4. Without making your '12-'14 illegal, you will NEVER get it to do what a '18 can do as far as takeoff and landing performance.

Another reason to go experimental!!
 
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