Thanks Thanks:  0
Likes Likes:  0
Results 1 to 6 of 6

Thread: engine mounts, the long and short of it?

  1. #1
    Laz's Avatar
    Join Date
    Apr 2003
    Location
    Girdwood, AK.
    Posts
    116
    Post Thanks / Like

    engine mounts, the long and short of it?

    The drawings of the 2+2 experimental (PA 14 knockoff)I'm working on quit at the firewall (it says buy our mount). But since this is for fun and education, and I have just bought a new bottle of argon? I was over at Stoddards today and noticed a PA 12 mount will bolt up alright. What is the general opinion of long and short mounts? Also, does anyone have any info on where the thrust line is supposed to be? The 12 mount is not 90 degs. to the firewall, but the fuselage datum line is. I have an 0320 I'm planning to use, and I have built cub gear (+3" ) and tail feathers. I'm planning to keep it light as is reasonable. What are your 14s using?
    Thanks for any input!
    Laz

  2. #2

    Join Date
    Apr 2003
    Location
    Clearwater,Fl
    Posts
    2,596
    Post Thanks / Like
    One things for for sure, the more power the more angle. I had Clyde Smith Jr. tell me that some of the high torque is factored out by a slight or maybe not so slight verticle stabilizer deflection installed at the time of assembly. Now how much is enough is anybodies guess. But I would at least factor some in at the fire wall and plan for some additional correction for the future. The person that restored my 12 finally put a rudder trim tab on the plane to get to fly relatively straight at cruise. Personally I wish it wasn't there for cosmetic reasons. My 94 supercub requires a little rudder input at cruise to keep it straight. Hopefully sombody who's built 2 or 3 has will comment.

  3. #3
    StewartB
    Guest
    Laz,
    Here's my thinking for my 12. A 12 originally had 108 horse on the standard mount. People started putting o-320's on the mount to get hp, but the engine/prop combo were heavier, so the CG moved forward. Most guys balance it out by carrying weight in the back. A short mount gets the CG closer to original, but you can't push as much weight to the back. I'm using the short (Crosswinds) 160hp mount and will have a cargo pod for heavy stuff. That way I can fly heavy or light, without ballast in the back.

    As far as thrust, I know 18 guys that tilt the mount up, and like it. I don't know anybody that's done it on a 12 or 14. The AOI and tail geometry are different enough that the Cub mod isn't an automatic for a 12/14, but it may work. That's a question for smarter guys than me.
    SB

  4. #4
    Crash's Avatar
    Join Date
    Apr 2002
    Location
    Nikiski Alaska
    Posts
    2,695
    Post Thanks / Like

    Mount

    Stewart hit it on the head. I used Cross Winds STOL short mount 160 hp conversion STC. When it was weighed and the CG envelope figured out, it came in almost exactly the same as the original PA-14 with the O-235 108 hp engine. My CG envelope is amazing for a plane this size. Crash

  5. #5
    PA12driver's Avatar
    Join Date
    Feb 2002
    Location
    Battle Ground, WA
    Posts
    1,460
    Post Thanks / Like
    The answer is if you are just starting out (USE THE SHORT MOUNT) that is if you don't already have all the firewall forward and you don't mind being Slow!

    My 12 has the std beefed up long mount 12 muffler and cleaned up exhaust. PA18 tail, 18 66" flaps and 6" extended gear on 31" tires and it is nose heavy empty, it will haul a lot of weight aft and it gets off pretty decent but with the added drag (lots) it is slow and when you load it up it is even slower. (makes a good float plane with significantly less drag)

    It is really fun to fly empty and 50lbs in the extended baggage. To do over I would do as Crash just suggested! (period)

    Tim

    PS: Crash hows the 18 doing??

  6. #6
    Laz's Avatar
    Join Date
    Apr 2003
    Location
    Girdwood, AK.
    Posts
    116
    Post Thanks / Like
    Thanks for the information everyone! It looks like the short mount wins. Is there more than one short mount as far as dimensions go? Stoodards has one that (I think) has a Univair tag on it.
    Laz

Similar Threads

  1. Flaps for PA12 short or long
    By twoton in forum Cafe Supercub
    Replies: 8
    Last Post: 02-21-2009, 02:50 PM
  2. Long wing short fuselage
    By D.A. in forum Cafe Supercub
    Replies: 14
    Last Post: 10-29-2003, 10:07 AM

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •