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Post by Silverback on Mar 31, 2011 21:01:10 GMT 1
I used a coupla popsicle ( Is that spelled right?) sticks under the rear rear of the wing. this reduces the wings angle of attack ( and therefore lift), and helps to stop the plane doing the up'n'over with a brushless motor ( worked for me anyhoo!) Huh, I wonder if that's a better approach or if raising the front of the elevator a little would be better? My instinct is that adding lift at the back of the plane is better than taking away lift, and that effectively that is also more similar to a little down thrust under throttle... OTOH, shimming the back of the wing should result in the nose being up slightly higher on landing making a 3 point easier and protecting the prop slightly (I suspect the best answer would be adding a bit of an airfoil shape to the elevator) |
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Post by flydiver on Apr 1, 2011 2:57:56 GMT 1
The lift from the wing comes from 2 factors:
- airfoil: that part won't change
- incidence (angle into the wind): That's the part being changed.
Both the airfoil and the incidence are designed and setup for a plane that has FAR FAR less power AND speed. Once you go high power high speed brushless it starts doing things that have made a lot of people unhappy and have wiped out a significant investment in time and money in seconds.
You cannot simply bolt in 2-4x the power and simply go fly without any side effects at all.
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Post by Silverback on Apr 1, 2011 16:15:43 GMT 1
Was that directed at my response or something else? If at something else, then I guess you can ignore some of this, but if at my question then I disagree on 2 counts:
- I'm not expecting more power not to make a change in how it behaves, I'm specifying a different change which I believe will give an overall more stable (less variable/more predictable) setup by changing the angle of incidence of the tail rather than the wing.
- adding more power in itself does not change the characteristics of the airframe, it might change it's operating envelope: lift comes from the airfoil shape and it's angle of incidence as you stated, but also from the vector (velocity and magnitude or speed) of the airflow over that airfoil. Changing the power applied does not intrinsically change this at all, it just might change the range of conditions that the combination might see in normal flight. In other words, even the extreme end of that performance envelope, lets say that adding the bigger motor will let you fly your SC with an average airspeed of 75mph over the airfoil in level flight, you could conceivably do the same for at least a short period with the stock motor by putting it into a dive till you achieve the same speed.
Point being, assuming that the rest stays the same (weigh, CG, the prop...) then a more powerful motor should allow the plane to operate in all the same ranges as the original at part throttle, and just add to the top end.
That said, I'm still curious if anyone has any input about my thought about making the changes at the tail vs the wing, I still feel it will be a better approach and result in less change in attitude to the same throttle input making the SC easier to fly with more power.
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