Power Effects on Trim Speed

[Crumpp]

Is anyone else experiencing this issue?

 

1. Trim the airplane for level flight at cruise power.

 

2. Add power

 

3. Airplane descends

 

The airplane should climb and remain or seek trim speed. Mine are not doing this anymore.

 

A track is included.

[Anatoli-Kagari9]

The p51d has neutral pitch stability at some CoGs ( important to know how your tanks were filled in that test... ).

 

I believe a rearward CoG would explain it :-)

Edited February 25, 2015 by jcomm

[Crumpp]

Except the result is the same nose high or low.

 

The fuselage tank was empty. Wings full.

Edited February 25, 2015 by Crumpp

[Yo-Yo]

I tried to get thie effect... the noticable nose down pitching effect begins as you increase prop rpm. And it's right because, as you can see, MP goes down and the total power decreases.

 

If only MP is increased the plane begins to build speed up rather than climbing because of almost neutral overall stability in power-on flight. This behaviour is distinctive for relatively high speed.

At low IAS (climbing) 2700/32 to 2700/61 transition causes readable pitch-up tendency (if yaw trim is applied properly as power increases).

You can estimate the trim curves in gliding condition (stick position vs IAS) and in power-on condition to see what happens especially at low IAS.

THis is an illustration for the reports you mentioned (I am afraid that the most interesting report for powerful airplanes you missed... or maybe I missed it in your references :)).

Positive stability at gliding becomes neutral or even negative at full steam.

 

By the way, we tested the behavior at power transitions comparing to the real Mustang.

[TAGERT]

THis is an illustration for the reports you mentioned (I am afraid that the most interesting report for powerful airplanes you missed... or maybe I missed it in your references :)).

 

By the way, we tested the behavior at power transitions comparing to the real Mustang

Another interesting difference between powerful WWII props and modern low powered civilian aircraft! It's good to know your guys are on top of those differences! S!

[Crumpp]

I tried to get thie effect... the noticable nose down pitching effect begins as you increase prop rpm. And it's right because, as you can see, MP goes down and the total power decreases.

 

If only MP is increased the plane begins to build speed up rather than climbing because of almost neutral overall stability in power-on flight. This behaviour is distinctive for relatively high speed.

At low IAS (climbing) 2700/32 to 2700/61 transition causes readable pitch-up tendency (if yaw trim is applied properly as power increases).

You can estimate the trim curves in gliding condition (stick position vs IAS) and in power-on condition to see what happens especially at low IAS.

THis is an illustration for the reports you mentioned (I am afraid that the most interesting report for powerful airplanes you missed... or maybe I missed it in your references :)).

Positive stability at gliding becomes neutral or even negative at full steam.

 

By the way, we tested the behavior at power transitions comparing to the real Mustang.

 

Good stuff Yo-Yo! Thanks for the quick response! I was hoping to hear you were working on getting our force reversal's modeled!!!

 

:-)