Help with Stearman PT-17
06-16-2009, 05:45 PM
#1
Member
Thread Starter
Join Date: Sep 2006
Location: Franklinville,
NJ
Posts: 49
Likes: 0
Received 0 Likes
on
0 Posts
Help with Stearman PT-17
My PT-17 Stearman had her maiden flight atmy club's BBQ yesterday. All went well for the most part. Got alot of compliments from the guys on how nice she looked. The only problem I'm having is she wants to climb, even at 1/4 throttle. I did balance it as per the manual, and it's actually a little nose heavy! I had to give it alot of down trim to level it out. Any ideas?</p>
06-16-2009, 06:27 PM
#2
Join Date: Nov 2005
Location: Poolesville, MD
Posts: 12,624
Likes: 0
Received 0 Likes
on
0 Posts
RE: Help with Stearman PT-17
Stearmans do not use symetrical wings, so the do tend to climb at higher throttle settings.
However it sounds like something is not quite right.
Here is a few things to try.
- Take it up and fly with the throttle about 80-85%. Then trim the plane so it flies level. ( Yes you may have to trim down elevator ).
- As the now trimmed plane is approaching a flyby past you, cut the throttle completely while NOT moving the elevator.
- What does the plane immediately do, nose up? or nose down?
If it noses down, you need more down thrust on the engine, and you still need to trim the plane for level flight!
If it noses up, you need more up thrust on the engine, and you need more down trim on the elevator.
The idea is that the plane should not climb or decend as you pull off the throttle, rather it should stay momentarily on the SAME PATH ( be it climb, decent or level ) it was on.
Once you've established that and corrected....
- Fly the plane again, and trim for level flight as before.
- Now roll it inverted on a pass. You should need only a bit of stick movement for the ailerons to keep it flying level.
If not take it as high as you can, point the nose straight up and chop the throttle to idle.
- Let the plane go straight down so you can see it from the side.
- As the plane is diving do not touch the ailerons.
Does the plane pull to the canopy or belly during the dive? ( it should not do either really but some pull to the Canopy is normal for a biplane. ).
You can also tweak your wing incidences a bit.
If your plane is climbing too much loosen the bolts and resize or change the holes on the rear pieces so that the wings sit SLIGHT more level. You only want to move it about .5 to 1 degree. A VERY TINY AMOUNT!
Then fly and test again.
The Stearman usually has positive wing incidence, but if it is climbing too much, you can bring it down just a bit to correct this.
However it sounds like something is not quite right.
Here is a few things to try.
- Take it up and fly with the throttle about 80-85%. Then trim the plane so it flies level. ( Yes you may have to trim down elevator ).
- As the now trimmed plane is approaching a flyby past you, cut the throttle completely while NOT moving the elevator.
- What does the plane immediately do, nose up? or nose down?
If it noses down, you need more down thrust on the engine, and you still need to trim the plane for level flight!
If it noses up, you need more up thrust on the engine, and you need more down trim on the elevator.
The idea is that the plane should not climb or decend as you pull off the throttle, rather it should stay momentarily on the SAME PATH ( be it climb, decent or level ) it was on.
Once you've established that and corrected....
- Fly the plane again, and trim for level flight as before.
- Now roll it inverted on a pass. You should need only a bit of stick movement for the ailerons to keep it flying level.
If not take it as high as you can, point the nose straight up and chop the throttle to idle.
- Let the plane go straight down so you can see it from the side.
- As the plane is diving do not touch the ailerons.
Does the plane pull to the canopy or belly during the dive? ( it should not do either really but some pull to the Canopy is normal for a biplane. ).
You can also tweak your wing incidences a bit.
If your plane is climbing too much loosen the bolts and resize or change the holes on the rear pieces so that the wings sit SLIGHT more level. You only want to move it about .5 to 1 degree. A VERY TINY AMOUNT!
Then fly and test again.
The Stearman usually has positive wing incidence, but if it is climbing too much, you can bring it down just a bit to correct this.
