Bill,
No disrespect intended, but what you're not doing right is pulling full
flaps at 75 mph. Most full-house planes thermal around at 20-30 mph.
First go out and fly your plane. Get it nice and high and [ut your plane in
a dive to get the airspeed to 75 mph. Then pull full flaps... suddenly.
Tell us what happens. BTW, don't try this anywhere near the ground. I
guarantee that any elevator compensation you have programmed in will be
completely wrong.
After you try it, I am willing to be corrected. But I believe 75 mph is not
a reasonable speed to expect a flap servo to hold up. I've done it at high
speeds before and it is not fun.
Jon Stone
> One of the really neat things about the Multiplex web page is the
> calculator that will help predict the right sized calculator for an
> application. check out:
>
> http://www.multiplexrc.com/calcservo.htm
>
> OK, given that it is an approximation at best, I still get some really
> strange numbers. I'm probably using it wrong.
>
> Given your basic 125" sailplane. weighs say 70 oz, flaps are 2x25 inches,
> they deflect 90 degrees, the wing has a 10" chord and the plane is moving
> at say 75 mph. Yes, this is fast, but not unreasonable for a dive. For
me
> the servo calculator gives a required servo of 112 in oz. This is a huge
> servo. Most of us would find a Hitec 225 MG with 55 in oz adequate.
>
> On the other hand, given an aileron on the same plane, again say 2"x25"
> that moves only 30 degrees then the required servo must carry only 37 in
oz
> and an HS 85 at 42 in oz.is more than adequate.
>
> Am I doing this right? Whenever I try to come up with a value for flaps,
> it always seems about twice as high as folks use successfully. What am I
> missing?
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