On Apr 5, 4:31*am, Eric van Geetsum wrote:

replace the big heavy mainwheel and tyre by new TOST or Beringer
lightweight aloy wheels

Lighter weight wheels are often less durable, and more prone to
breakage. And I don't know about the ones you mention, but I rather
doubt that they are much lighter than the original.

Grind down the very thick (GROB style) gelcoat to a minimum

That's an interesting candidate. Gelcoat generally runs .012" to .020"
thick, and weighs about 10 lbs/gallon. A Grob twin is going to have
about 520 ft^2 of painted area, so there'll be around 1200 cubic
inches of gelcoat on it; that's around 5.2 gallons and about 52 lbs.
However, the gelcoat is rarely very evenly applied, so some spots will
be thicker than others. If you try to sand some of it off, you won't
get very deep before you get to green in some spots. You might get
maybe 1/4 of it off before that happens Then you either leave those
areas and sand others, resulting in an uneven surface, or you stop
there. After the sanding, you'd probably end up applying a gallon or
so of finish to clean it up some. That sounds to me like a rather
dubious enterprise.

Replace the battery for a LiPO type
Remove radio and electro sink-clim indicator incl all electrica wiring.
Remove all pollstry.

And then?????????

Someone recognises this problem and who encouterd a solution??

All aircraft gain weight as they age, and they generally gain more
than anybody expects. I think maybe it is proof that dark matter
exists.

I think that the thing to do is, at next annual inspection, first
clean out all the dust and dirt and grime from everywhere that you can
reach. Then, as you suggest, strip the instrumentation and wiring down
to the bare minimum. I think you need the radio and antenna, but maybe
use a newer, lighter one. Remove any extra plumbing. Recruit lighter
instructors.

Thanks, Bob K.