REFLECTOR: Thrustline change
Brian Michalk
michalk at awpi.com
Fri Mar 29 16:26:59 CDT 2013
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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