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Thread: more nose up trim needed

  1. #1
    skukum12's Avatar
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    more nose up trim needed

    Empty or heavily loaded, my 12 runs out of nose up trim. Always doing approaches with the stick hard back and quite frankly it is getting old.

    I look at bunches of 12s on the ramp and all of them seem to have the horizontal all the way to the stop. What is the best solution going nowadays? Bigger elevators, VGs on he tail, airfoil stabs, gap seals, lead? Will a short engine mount help enough to justify cost and time?
    "Always looking up"

  2. #2
    skywagon8a's Avatar
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    When in full nose up position does the leading edge of the stabilizer rest on the top of the top longeron? It should. Seaworthy had this same problem and found that the yoke was upside down.
    N1PA

  3. #3
    Scooter7779h's Avatar
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    I had a -12 79H with long mount for 30 years, 3400 hours in it. Empty CG was right at 12", forward limit. Only when loaded at minimum weight with forward CG would I run full nose up trim. Most loading configurations the trim was not full nose up if you trimmed off pressures, and I usually would for landing and takeoff. For three years and now about 250 hours I have been flying the -12 MCS Mike built for Sierra Bravo which has Charlie's short mount. Mike had rebuilt 79H too for me and for the most part had the same mods on 53M. Within a few hours I knew the short mount was a world of difference better. With this plane I never trim at all from cruise setting all the way to landing. Transitioning from deploying flaps and slowing down I have some stick pressures but not bad, and once slowed to 40 pretty much neutral pressure. I do have elevator/rudder gap seals on 53M which I got field approved but only made elevator more responsive didn't change stick pressure any. Both had mirco VGs, but 79H did not have them on the tail as I got them field approved before the STC and tail VG part. With the short mount the sight visibility over the nose is more similar to a widebody -18 than a -12 with the long mount. I do not find there is any load I cannot put in the belly pod or extended baggage's (both -12s had them) that is limited by the different CGs, just load it a little differently.

    I was always a naysayer about a short mount till I got one, now a believer that this is one of the really good -12 mods. I only trim a half a crank or so in cruise to make sure its hands off level and don't touch it for landing. This trim setting pretty centered on the jackscrew. YMMV but I think having a good flying -12 is all about knowing the planes and building everything right and rigging it right. Anomaly about trim and pressures tells me there probably other things going on with the plane than just elevator trim that manifest in the way the plane flys.
    Last edited by Scooter7779h; 09-03-2015 at 11:09 PM. Reason: spelling
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    PA-12 fan

  4. #4

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    My first tail dragger was a J5 with a cowled O235-C1. It's a great plane to fly but it's a little nose heavy and would run out of elevator. Carrying power on landing made things easier.

    When I bought my PA-12 to rebuild, I knew I wanted the short mount conversion when I put the 320 on. I lucked out and found a 160hp firewall forward pa-18 setup which made things easier for the conversion.

    The plane flys like a dream. There is a reason Piper started putting the engines closer to the firewall.

  5. #5

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    I'm concluding that you are flying a stock 12 down in the lower airspeeds like 55 or less. If so what you are experiencing is normal. It takes power and a hand full of stick to land slow in a stock 12. On the ground check to insure that when your trim is all the way down the elevator is pitching up , don't recall how much but in general better than 30 degrees I'd guess. This at least tell you the bungee spring is installed. Many airplanes have removed them, why I couldn't tell you.

    Quote Originally Posted by skukum12 View Post
    Empty or heavily loaded, my 12 runs out of nose up trim. Always doing approaches with the stick hard back and quite frankly it is getting old.

    I look at bunches of 12s on the ramp and all of them seem to have the horizontal all the way to the stop. What is the best solution going nowadays? Bigger elevators, VGs on he tail, airfoil stabs, gap seals, lead? Will a short engine mount help enough to justify cost and time?

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