Kolb Ultrastar Problems

[123.net]

I recently purchased a 1984 Kolb Ultrastar from the original builder. I had
it test flown yesterday and a problem was noted.

I am having a problem with the aircraft not gaining altitude as it should.
Problems with the engine have been ruled out (Runs Great!!) But when full
power is applied, the aircraft seems to "mush" and lose ailtitude instead of
gain ailtitude. Once power is let up, it climbs again, but not very well.
We think it may have something to do with the aeodynamics of the cockpit.
(Not the original design) It does not "nose down", just sorta sink. I am
unable to contact the original builder at this point. Please take a look at
the pictures and see what you think. Also, I have noted that there is only
20 degrees elevator up, but 25 degrees elevator down. According to the
original build plan, it should be 9" up and 9" down as measured from the
most aft part of the elevator. I am currently working to correct this.

I've already contacted Kolb in this matter, but would like to know what this
group thinks.

Pics are located at:
http://mula.perrydice.com/robsnew.htm

Any help you can give would be GREATLY appreciated.

Thanks,
Rob Perry
Michigan Ultralight Association
Webmaster
webm...@perrydice.com

[DRMusgrove]

>But when full
>power is applied, the aircraft seems to "mush" and lose ailtitude instead of
>gain ailtitude. Once power is let up, it climbs again, but not very well.

Okay - here are a couple of pot-shots. Considering the Ultrastar with the
ULII02 should climb like a batoutahell, I would look into the following:

Check your engine thrustline against the plans - I cant' tell from the pics
what it is of course. The thrustpoint is so near the CG that an incorrect
angle will act more like a JATO, i.e.- shove you up or down, rather than pitch
you.

Check your CG again, both empty and in actual flight trim (basic weight &
balance).

If these things don't yield results, wait for Homer's answers. The Ultrastar
we are flying has a very solid climb even at half power. A wonderful flying
machine. I wish you good luck in your diagnostics so you can enjoy the great
flying qualities fo this bird.

David M.

[John Anderson]

After looking breifly at your pictures, I would say your weight and balance
is off. In the pictures your gas tank is behind the seat, pushing the
pilot seat forward. In my Ultrastar, the seat is all the way back where
the gas tank is and I can affect performance and/or make it go up or down
by leaning forward or back.
Think you should start by hanging your bird and checking balance.

123.net <per...@123.net> wrote in article
<Q1MN2.25$et2....@news15.ispnews.com>...

> I recently purchased a 1984 Kolb Ultrastar from the original builder. I
had
> it test flown yesterday and a problem was noted.
>
> I am having a problem with the aircraft not gaining altitude as it
should.

> Problems with the engine have been ruled out (Runs Great!!) But when

full
> power is applied, the aircraft seems to "mush" and lose ailtitude instead
of
> gain ailtitude. Once power is let up, it climbs again, but not very
well.