Sapac Hawk - RC Groups
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This thread is privately moderated by Herb, who may elect to delete unwanted replies.
Aug 11, 2010, 04:03 PM
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Build Log

Sapac Hawk

I got this one from Gregg for $40. It was a v1 version, so I got a set of FG ducts from sapac, instead of those comical vacuformed plastic ones. The rest of the ducting I did as usual with mylar.

It's a nice weekend flier, the wing's a bit too thin & flimsy for retracts so I eventually used fixed gear instead (kiss principle).

I've had about 15 flights on it, and it's nice and fast on ca. 1200W. But a bit of a vicious tipstaller in tight turns, if you slow it down too much.

Guy H took the very nice in-flight pictures below (Canon 7D).

Last edited by Herb; Nov 11, 2010 at 02:06 PM.
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Aug 11, 2010, 08:48 PM
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Do you think wing fences would help the tip stall? Maybe some reflex?
Aug 12, 2010, 01:11 PM
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Yes and yes

My kit did not have the wing fences, they got lost somewhere in transit ...

The problem is of course that the wing is designed to be rather thin to get speed ... as a result the Hawk is indeed quite fast & low drag.
Nov 19, 2010, 01:42 PM
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I noticed after a few months of flying that the Sapac Hawk does have a bit of a tipstalling tendency in moderately tight turns.

Not sure if this is a generic characteristic of the Hawk wing geometry, or is due to the specific choice of (relatively thin) airfoil.

In any case, I decided to try out a pair of good-sized wing fences -

If they have any noticeable effect I might try that later in the CMP T-45 as well ... I noticed Rolf also has fences in his DS T-45.

Nov 19, 2010, 01:49 PM
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Even the E-Flite Hawk has wing fence, so I think they probably really are functional than just cosmetic. Anxious to see how your CMP T-45 flies with/without them...
Nov 19, 2010, 03:09 PM
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Yes absolutely indeed, you are right that's another reason why I decided to fit them in the Sapac Hawk as well

It is interesting that the full sized Bae Hawk has fences, while the T-45 (licence built, modified Hawk) has many tiny turbulence generators.


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