Rear of plane lifting first during take off

[Philip Beck]

I received my plane out of annual a while back and haven't been flying as much as I would like...so when I'm taking off it feels like the rear of the plane is trying to lift before the front of the plane.  Anyone else experienced this type of thing?

[N201MKTurbo]

26 minutes ago, Philip Beck said:

I received my plane out of annual a while back and haven't been flying as much as I would like...so when I'm taking off it feels like the rear of the plane is trying to lift before the front of the plane.  Anyone else experienced this type of thing?

Move the trim indicator about 1/8 inch more nose up before take off.

Did they do anything to the trim system?

[Bob - S50]

Pretty common. Hold nose up pressure during takeoff roll.

[carusoam]

Congrats on the first post Phil!

Long Body question...  which means the answers will be in kts... where the other Mooneys May be in mphs...

1) Typical Mooney behavior...

2) pull back on yoke, around 65 on the ASI..

3) hold/set attitude...

4) Tap brakes just because...   proof your memory is still working at full speed...

5) Raise gear...

6) execute departure checklist... fuel pump, flaps...

7) Waiting too long to supply back pressure... the nose stays planted on the ground...

8) Check your ASI, flap and trim indicators for any changes... (more flap than desired/expected, will cause the nose down tendency) (flap position relay/sensors can get out of adjustment easily with age)  the panel mounted flap position will accurately present the flap position... the automatic positioning of the flap may be 5° off...

9) Check your stall warning as well... on landing, some people will get a decent announcement of their arrival via their stall warning device... if you usually get one, does it no longer work the same way?

10) do you have any flying related fears..? 

These are things that can alter your perception of actual speed... or the way the wing generates lift... or how fast you are actually going...

PP thoughts only, not a CFI...

Best regards,

-a-

[Danb]

Having a Bravo I’ve not experienced the phenomenon.

During my takeoff roll I monitor my gauges in a circular pattern right to left, 

airspeed will now be in the low 50’s- I then apply the lightest backpressure on the yoke as I near rotation speed, given another quick of instruments along with my progress down the runway, my last decision is to go or stay, hopefully go, I continue to hold the plane off, at the proper speed and configuration I continue at my desired climb out Vx vy or whatever.

Ive considered my next move , a return to airfield, offsite landing etc. contact departure and off we go.

[Philip Beck]

Thanks for all the comments, I took my 5000 hr CFI with me, though he's not a Mooney expert, he was a little surprised.  That's why the question here, it's not normal as I have several hundred hours in a 201, probably only about 40 in the Bravo.  After the annual, I'm guessing something was not put back together the same, the mechanic had no answers, again looking for 'expert' opinions that have had the same experience.  Too much back pressure and you're 'jumping' off the runway at 60kts, I don't want to come back down one of these times.  Obviously, the Bravo has enough HP that I'm going to climb straight out, but something's different. 

Edited May 14, 2020 by Philip Beck

[HRM]

Just now, Philip Beck said:

Thanks for all the comments, I took my 5000 hr CFI with me, though he's not a Mooney expert, he was a little surprised.  That's why the question here, it's not normal as I have several hundred hours in a 201, probably only about 40 in the Bravo.  After the annual, I'm guessing something was not put back together the same, the mechanic had no answers, again looking for 'expert' opinions that have had the same experience.  Too much back pressure and you're 'jumping' off the runway at 60kts, I don't want to come back down one of these times.  Obviously, the Bravo has enough HP that I'm going to climb straight out.  

Wise to ask it. Anything odd with a Mooney tail (excepting the design, of course) deserves scrutiny. It's a complex system.

[dzeleski]

If I dont apply back pressure during takeoff my J does the same thing when its just me in it, you need to be aware of this because its a great way to get a new prop and engine. If I have passengers its less likely to do it.

That being said when the plane is light (< half tanks) and just me I add a little extra nose up trim and I dont have this problem. Plane rotates with very little pressure (5lbs maybe?).

[hypertech]

35 minutes ago, Philip Beck said:

Thanks for all the comments, I took my 5000 hr CFI with me, though he's not a Mooney expert, he was a little surprised.  That's why the question here, it's not normal as I have several hundred hours in a 201, probably only about 40 in the Bravo.  After the annual, I'm guessing something was not put back together the same, the mechanic had no answers, again looking for 'expert' opinions that have had the same experience.  Too much back pressure and you're 'jumping' off the runway at 60kts, I don't want to come back down one of these times.  Obviously, the Bravo has enough HP that I'm going to climb straight out, but something's different. 

I'm struggling a bit with what could have possibly been done at the annual.  Unless he re-rigged something or (un)installed something that changed the
CG, which should be in your log entry, its just inspect and lubricate.  What is your trim setting?  I prefer a little less nose up so I don't leap off the runway before its really ready to fly.

[Bob - S50]

1 hour ago, Philip Beck said:

Thanks for all the comments, I took my 5000 hr CFI with me, though he's not a Mooney expert, he was a little surprised.  That's why the question here, it's not normal as I have several hundred hours in a 201, probably only about 40 in the Bravo.  After the annual, I'm guessing something was not put back together the same, the mechanic had no answers, again looking for 'expert' opinions that have had the same experience.  Too much back pressure and you're 'jumping' off the runway at 60kts, I don't want to come back down one of these times.  Obviously, the Bravo has enough HP that I'm going to climb straight out, but something's different. 

Sorry, I did not notice you were flying a long body.  I was talking about a J.  I've seen videos on line taken with a camera mounted on the belly that showed the mains getting airborne while the nose was still on the ground.  When we first got ours, I noticed it was difficult to keep the plane from starting to scoot sideways in a crosswind as I approached liftoff speed.  By holding back pressure it adds a download on the tail which in turn adds weight on the mains and reduces weight on the nose.  This helped keep the mains firmly planted on the ground until the plane was ready to fly.

If you suspect something they did at annual...  Did they do any work on the nose gear that would raise the nose (like new pucks)?  Did they mess with the trim system, and if they did, does the nose feel heavy after liftoff?

[Philip Beck]

You might be on to something, I did have new pucks installed, but I'm struggling to understand how new pucks could cause this.   I'm thinking on top of that maybe the trim was changed, but it just feels like the back end is too light and is ready to fly before the rest of the plane. 

I was just thinking maybe the oxygen tank got slid forward somehow during annual that would definitely move the CG forward. 

[Bob - S50]

5 minutes ago, Philip Beck said:

You might be on to something, I did have new pucks installed, but I'm struggling to understand how new pucks could cause this.   I'm thinking on top of that maybe the trim was changed, but it just feels like the back end is too light and is ready to fly before the rest of the plane. 

I was just thinking maybe the oxygen tank got slid forward somehow during annual that would definitely move the CG forward. 

New pucks on the nose will raise it up.  That will increase the pitch angle of the wing, which becomes the AOA while rolling down the runway.  Higher AOA will increase lift from the wings.  Since the weight didn't change, the wing will be ready to fly at a lower speed.  Since we normally fly with the CG forward of the center of lift, the nose will want to stay on the ground even though the wing wants to fly.  By applying back pressure, you increase weight on the mains and reduce weight on the nose.  That increases the speed at which the wing can fly at the AOA while rolling down the runway and makes it easier for the nose to get airborne.

[FoxMike]

You may have already done this but talk to the folks who did your annual and describe the problem to them.  The trailing edge of the elevator is supposed to be bent down 7d.  If you did not take your plane to a MSC someone might have thought to straighten it would be good.  Lots of mechanics have worked on Mooneys but may not have experience with long bodies.

[Bravoman]

Could one of the batteries have been left out?

[Danb]

Mike and Bob have good points, I’d venture to bet it’s do to the new pucks, we have a heavy plane, I don’t know if you mentioned if you have long range tanks.thats a hell of a lot of weight on the mains. Considering how much play was in the old pucks versus new ones with tight tolerances you’ve answered your own questions. When my pucks were changed I clearly noticed the difference especially on the ground. 

[Philip Beck]

Thanks for the help everyone, I'm pretty sure now it's actually a combination of the new pucks AND the trim being slightly off- which really emphasized the new AOA

 

Edited May 21, 2020 by Philip Beck

[carusoam]

Great follow-up, Phillip!

Best regards,

-a-

[N201MKTurbo]

My boss has a beautiful A36. I have quite a few hours of right seat time in it. Whenever there is a passenger or two in the way back seats, he tells me to be careful on takeoff because the nose will go way up after liftoff. I tell him to set the takeoff trim about 1/4  inch to the nose down from the takeoff mark when he has passengers. He refuses! He says you have to set it to the takeoff  position. I just roll my eyes.

[skykrawler]

If the Bravo has continuous flaps like the J/K reduce the flap setting a little which will require more pitch for take off.

[alextstone]

On 5/21/2020 at 12:23 AM, N201MKTurbo said:

My boss has a beautiful A36. I have quite a few hours of right seat time in it. Whenever there is a passenger or two in the way back seats, he tells me to be careful on takeoff because the nose will go way up after liftoff. I tell him to set the takeoff trim about 1/4  inch to the nose down from the takeoff mark when he has passengers. He refuses! He says you have to set it to the takeoff  position. I just roll my eyes.

Either you fly the airplane or you let the airplane fly you (into the ground).

[jlunseth]

I had this issue with my 231 and many years ago a Mooney instructor taught me to just set the trim to somewhat nose up on takeoff. I have a checklist item that says “Trim set for takeoff.” I just put the trim in that same slightly nose up position every time. I have been doing it so long I don’t even think about it.