Elevator Control Authority

[bill_e]

Hey everyone, I'm scratching my head over what seems like a lack of pitch authority when attempting to do a 3-point landing. It's something that has bugged me since I bought the airplane and I really paid attention to it while flying yesterday. Long story short, at 70mph indicated, I hit the aft pitch stop with the yoke before the airplane assumes a 3-point attitude. I need a short blip of power before I touch down to get all three wheels to hit at the same time. This definitely seems wrong, but I'm not sure what the cause might be.

Weight and balance yesterday put me at 1350 lbs and 17 inches aft of the datum, so should be on the tail-heavy side of the envelope. Using a hardware store angle gauge, it looks like I'm generally getting the 20 degrees up and down deflection specified in the TCDS too. Has anyone else had a similar experience? In the meantime, I'm getting good at wheel landings...

[6597]

I had a similar issue. Turned out to be 2 things....

1. I had the wrong tailwheel spring set-up for my bird i.e. had the double bend set when I should have had the single bend set for my serial#. I got my tail about 3-4" lower by changing out.

2. My trim tab did not have the full throw, re-adjusted and I was able to get the tail down with no effort.

I still can't make perfect 3 pointers, but now I know it's me instead of the plane!

[bill_e]

I actually just installed new tailwheel leaf springs from Univair over the winter, so I can confirm they are the correct single bend variety for the earlier serial numbers (I'm 10109). I didn't think to look at the trim throws, but I can go check that easy enough. For what it's worth, I can trim the pressure off the yoke to keep the airplane at 70 mph in a power-off glide with margin for more up-trim on the trim wheel, so I didn't suspect trim was the problem. Which direction was your trim adjusted and how did it affect your setting for landing?

[V529]

One question:
Are you landing with full flaps?

If.......you are ...landing with full flaps, try no flaps.

After having flown all variations of our aircraft I decided the only thing that flaps do for the 140s is:
A. help you a little on wheel landings
B. Hurt you a little more on 3 pointers.

I'll be curious as to your answer/investigation.

[6597]

Which direction was your trim adjusted and how did it affect your setting for landing?

I didn't have enough 'tab down' and had to use more back pressure on the yoke. Got it corrected. Still make less than perfect 3 pointers....

After having flown all variations of our aircraft I decided the only thing that flaps do for the 140s is:
A. help you a little on wheel landings

I make real good wheelies. I use the patented Domeyer Variable Flap Setting Mode to grease it on....

[6643]

Can you do a power-off stall? If so, you have enough up elevator.

A bit of trivia: full nose down trim increases the effectiveness of the up elevator, and vice-versa.

[bill_e]

One question:
Are you landing with full flaps?

If.......you are ...landing with full flaps, try no flaps.

Preferred flap settings was going to be my follow on question. Yes, flaps only make things worse. For whatever reason, I've got something like 6 different detents the flaps can be set to which seems completely unnecessary. I've only used full, approximately half, and no flaps. No flaps is by far the best, but not a cure.

As to power off stalls, I only ever get a relatively stable mush stall. Sometimes it will develop into a mild phugoid, but I've never gotten a sharp break like with power on stalls. This didn't seem unexpected, so I figured this was normal stall behavior. I haven't tried power off stalls with flaps up though.

I'll also happily concede this could entirely be a technique issue on my part. The 140 is by far the lightest airplane I've spent much time in and I'm noticing plenty of places where I don't have the momentum I'm expecting/planning for. Maybe I'm just rounding out too soon because my brain is still calibrated for twice as much airplane.

[4004]

From an old timer, soloed July 1946, one has to remember (or consider) that there was lots and lots of GI Bill training going on post WW2 and the 140s were "advanced trainers" after basic in a J-3/Champ. The flaps were primarily training devises and most of the instructors were former WW 2 pilots - in fact all of my instructors thru commercial were such. FWIW 2c

[meloosifah]

I don’t know the fix, but I would say you are shy of elevator for some reason. I can get my plane to break on power off stalls and I can easily stick my tailwheel on the ground before the mains - in fact I’ve found the 3pt is easier when the tail just kisses the ground before the mains. But I can easily put the tailwheel on before the mains.

Are you confident in your W&B? Any chance your elevator trim is not adjusted correctly?

[V529]

Elevator travel is in the Type certificate. I'm traveling so I don't have access to it. I think........?? it's 20 degrees up and down.

That being said, you can get pretty mild power off stalls if you just east into them. If you keep the ball centered, you can enter in a flying leaf, it will just slowly mush down and it will oscillate stall, semi recovery, stall, semi recovery, and so on. It's pretty neat. If you have the correct amount of elevator travel, .........your airplane may be normal.........?