Karl,
I normally get 57 degrees and can tweak 60 but usually don't bother for
the last 3 degrees.
See the notes from my shop instructions attached.
I have not minded the pull effort, as they stay at 50% for landing
normally. Above 85 knots it is a heck of a pull past 50%. John Bolyard
and I have discussed putting holes in his airbrake trailing edge to
decrease the deployment effort (as in the Dauntless) or lengthening the
leading edge and fitting holes to prevent rapid pressure build up or
they will flop wildly open. Unfortunately it will be manual research
and trial and error on my part until the factory planes are finished and
tested... NASA, or NACA more accurately, and the Air Ministry documents
(see one example above in .pdf) are far and few between on air brake
analysis as dive or airbrake research was proprietary data of
manufacturers who used hydraulics to move their airbrake. Our airbrake
is a copy of a Slingsby design which was quite successful, but something
went wrong in the translation.
Just a note to the others, the MG wings (about 34 sets) were sold only
by the original company to the US/North American market ( I think the
last set was produced in 2004) but unable to be flown in Europe until
recently. Today, Europa is ready to begin new MG wing production
certified under JAR-VLA and CS 22 requirements which make them stronger
and saleable world wide. It took Dave Stanbridge to make this happen.
Now the factory has two MGs being constructed and will be evaluated for
these kind of fixes. First a computerized aerodynamic evaluation was
made, followed by a detailed structural test, currently the rigging and
building is being evaluated, which will be followed by flight test and
airbrake fixes will surely follow.
Doesn't help your situation now I'm afraid. The airbrakes are not
dangerous as is but are very inconvenient to use without pumping up the
muscles. You can tell a MG pilot by the size of his right bicep.
I know we all are going as fast as time and money permit.
Bud
----- Original Message -----
From: Karl Heindl<mailto:kheindl@msn.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Saturday, August 28, 2010 6:50 PM
Subject: Europa-List: MG Airbrake question
Hi motorglider guys.
Has anyone made any changes to their airbrakes ? I find they requires
a lot of force to hold them in the fully open position. The air pressure
on the bottom half far exceeds that on the top.
Because of that it is also impossible to get the maximum deflection of
60 degrees. I mounted an angle indicator, and it shows about 45-50,
which severely degrades their performance.
I don't understand why nothing was ever done about this. They have
been producing these wings for about 11 years now.
The obvious solution to me is to reduce the area of the bottom half,
either by putting in holes, or trimming back the trailing edge.
These brakes are not really necessary with the engine running, but are
essential when I get to making dead stick landings.
Karl
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