increasing performance

[D.A.L]

As a winter project I have brought my fuselage home to fix it up
alittle and
re-finish it . My question is, just how much time I should spend
contouring, smoothing ect. as to not be wasting my time and money vs.
getting another L/D for my trouble? It's in pretty good conditon, a
bit of peeling paint(automotive), the right/front side of the canopy
sticks up about 3/16", alittle wavyness overall in the fibre glass,
and some dents in the fairing behind the main wheel (non-retractable).
The contruction is of fibre glass so do I need
to sand it right down, prime and paint or take the easy rout and sand
the bad spots, about 10% of the body, prime(?) and paint? I have also
read that the area where the wing meets the fuselage is quite
important, re:reduction of drag.
The wing root sticks out about 4" from the fuselage so should I mount
the wings and fair the two together or just leave it ? The performance
is between
30-33:1 with a wing profile similar to a 1-26 ( turbulant flow ?) so
will it really matter? She flies well but since I'm going to do some
work on her
anyway I figure I'd do some little mod's while I'm at it, if it would
be worth the time. I have re-finished the wings already so they are
not at issue.
Any suggestions would be appreciated.

Thanks, Don

[Ray Payne]

sell it

[Bob Kuykendall]

Earlier, D.A.L wrote:

> As a winter project I have brought my
> fuselage home to fix it up a little and
> re-finish it...

I think it would be easier for people to make suggestions
if they knew what type of glider you're talking about.
That way, folks who have developed type-specific approaches
can help out.

Also, you might find a type-specific forum to ask your
questions. There are Internet mailing lists and forums
for almost every glider type.

For what it's worth, my general approach to drag reduction
is, in general order of importance:

1. Seal leaks. No air should be allowed into or out
of the fuselage except in a controlled manner. Especially,
the wing/fuselage intersection should be completely
sealed. If possible, the gear well should be completely
sealed from the internal volume of the fuselage.

2. Fix all major discontinuities in the laminar areas.
Start by assuming that the flow will be laminar ahead
of the point of maximum girth on the fuselage, and
ahead of the point of maximum thickness on the wing.
Everywhere that there is a discontinuity (an edge or
a seam or a leak), the air will trip over into turbulent
flow, and the turbulence will spread laterally at about
a 14-degree included angle. Actually, the laminar flow
is pretty robust up near the nose, and gets more tender
as it approaches the point of max girth. That's why
one-piece canopies are generally better for lower drag.

3. Seal all control surface gaps as best you can. Three-tape
mylar is good. Internal curtain seals, if practical,
is best.

4. Get wing waviness down to .004' or less at least
in the laminar areas. Reducing the waviness is a lot
more important than absolute fidelity to contour. Contour
is pretty important, but you'd be surprised at the
contour variations I've found between 'as designed'
and 'as manufactured,' and even between right and left
wings on factory racers. And yet, such ships seem to
fly fine and win contests.

5. Ignore the fuselage aft of the wing fillets. If
it is structurally sound and doesn't have any holes
in it or clumps of mud stuck to it, it's probably about
as good as it needs to be. Spend your time elsewhere.

Beyond that, you can really make the ship seem to fly
nicer simply by making it a more pleasant place to
spend an afternoon. Sorting out the seating and the
cushions and headrest, and making sure that controls
and instruments fall easily to hand, makes flying a
lot less fatiguing and a lot more enjoyable. That can
improve your decision-making ability, and make you
and the ship a better-performing combination.

Others will no doubt have other, perhaps different
and better, ideas.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24