REFLECTOR: More on chutes

[DAlexan424@aol.com]

Subject: Re: BRS chutes & pusher canards?
From: johns022@duke.edu (David S. Johnson)
Date: 2/15/99 2:41 PM Pacific Standard Time
Message-id: <johns022-1502991641400001@ip203.minneapolis3.mn.pub-ip.psi.net>

From: RobertR237@aol.com
Date: Sun, 14 Feb 1999 10:27:45 EST
To: johns022@duke.edu
Mime-Version: 1.0
Subject: Re: BRS chutes & pusher canards?

> I'm thinking about building a Velocity,
>and the BRS emergency chute (ala the new Cirrus) is interesting. Talking
>with a company rep today at the MN Flight Expo, he said it wouldn't be a
>problem for the rope leading from the plane to the chute cords; assuming
>they wrapped up in the prop, it would hold, but only lead to a nose-down
>attitude. Cutting the chute cords or the chute itself would be pretty
>easy, though, so making sure the prop is just windmilling would be
>important. I dunno -- having any part of the thing wrap up in the
>prop sounds bad. Does anyone have any experience with this?
>Thoughts?

>EMAIL REPLIES PLEASE!>(thanks!)

>David

David,

First, let me say that I personally believe that BRS chutes have the potential
to greatly improve the safety record of general aviation.  I also believe that
their potiential may have been oversimplified by the companies trying to sell
them.

You concern about the cords getting entangled with the proper but probably
greatly overstated.  To understand this, take a close look at how the BRS
chute operates during deployment.  It is a rocket assisted deployment which is
meant to pull the chute out of it's compartment and up away from the aircraft.
The drag chute will open and continue to pull the chute out for deployment.
This occurs very quickly and would not likely be pulled down into the prop
area during the process.  This would be especially true for tractor
configurations and depending on installation should be equally true on pusher.

The problem with the Velocity and other canard designs might be a bit more
complicated.  The BRS chute must have several anchor points located around the
center of gravity for a loaded aircraft.  If you look at the Cirrus, you will
see that the chute is located directly behind the passenger compartment.  The
anchor points are at both sides of the windshield  and behind the passenger
compartment.  During deployment, it will pull through the outer surface of the
roof to center on the anchor points.  The anchor points must be structurally
sound to absorb the initial load imposed during deployment.  The issue with
the Velocity is where is the center of gravity?  If I recall correctly it is
just in front of the engine.  This would make the anchor points difficult to
get around the center of gravity for that type installation.

One final point, installation of a BRS chute system is more than just finding
someplace to store the chute until needed.  The entire design may need to be
altered to obtain the structural strength necessary to keep the chute from
ripping the plane apart during deployment.  The bigger the aircraft the more
design changes may be required.  For ultralights, this is usually no great
problem especially if it's a high wing.  Attach the chute to the main spar and
you are done.  Try the same thing on a 182 and you would have a totally
different problem.

So, after a 10 thousand word reply, my answer is basically this.  It can be
done but it is not a simple solution.  If you plan to try and install it on a
Velocity, I would highly recommend discussing the installation with the folks
from Velocity and get help in determining the proper methods to install.

Good Luck.