REFLECTOR: Thrustline change

[Brian Michalk]

Well, this is an experimental, and putting a washer under the mount 
attach point wouldn't be very difficult.

However, I don't think it will result in any airspeed improvement.

I do think it will put your rotation speed on takeoff a little higher.  
I noticed in my extensive high speed testing that nose rotation under 
power was at a consistently higher airspeed than under low power.  I 
don't know if this is because the engine thrust is above the CG, or if 
the thrust vector is putting force on the nose wheel.

If you want to lower your rotation speed, a very effective way to do 
that is to raise the angle of the plane relative to the ground.  For me, 
I am using an XL nose wheel.  The nose stands noticeably higher, and at 
takeoff speed, the nose bounces a few times, and eventually the main 
wing starts flying.  In the training I've done in Standard Elites, the 
small nose wheel must have the plane at near level, or even slightly 
negative attack. In that configuration in takeoff, when the wheel 
finally pops off the ground, the plane leaps into the air, requiring the 
pilot to release back pressure to prevent over-rotating.

On 3/29/2013 3:29 PM, Richard J. Gentil wrote:
> David,
>
> Think of it as reflexing your Canard. That is very efficient since you are removing lift and drag from the control surface.
>
> Richard
>
> Sent from my iPhone 5
>
> On Mar 29, 2013, at 1:29 PM, "David Ullman" <ullman at robustdecisions.com> wrote:
>
>> When I cruise with only me in the SEFG I have to put in 1/2 inch of down
>> trim (elevator up) or more.  This is clearly inefficient.  I already have
>> 18lb of lead in the nose and don't want to add more.  A friend suggested
>> shimming the top of the engine mount for a little downward pitch moment.  I
>> sort of like the idea but am worried that it might increase my take off
>> distance as it will drive the canard downward a little.  He thinks it may
>> help as the engine thrust line is slight more upward.
>>
>> Any thoughts or experiences?
>>
>>
>> David Ullman
>> N444DX
>> President EAA 292
>> 541-760-2338
>> david at davidullman.com
>>
>>
>>
>>
>>
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