REFLECTOR: barn door speed brake

Tue Oct 17 14:49:40 CDT 2006

Geez.  I was thinking the opposite...to re-enforce the panel with
embedded whatever to keep it from snapping in two aft of the jackscrew
attach point.
Terry

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Scott Derrick
Sent: Tuesday, October 17, 2006 10:29 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: barn door speed brake

Scott,

Actually I was considering drilling some large holes through my existing
brake to reduce the pressure but allow for a higher speed brake.   But
decided to work on increasing the gear extension speed instead..  

Scott

Scott Baker wrote: 

I'm thinking that a "half" size speed brake for RG models, with a higher

deployment speed, might be a drag option for enroute descents.

Anyone else have thoughts on this?

SB

----- Original Message ----- 

From: "Terry Miles"  <mailto:terrence_miles at hotmail.com>
<terrence_miles at hotmail.com>

To: "'Velocity Aircraft Owners and Builders list'"
<mailto:reflector at tvbf.org> <reflector at tvbf.org>

Sent: Monday, October 16, 2006 8:55 AM

Subject: Re: REFLECTOR: barn door speed brake

John,

Thanks for the comprehensive reply on the SB issues.  It sounds like our

situations are similar.  To add to your knowledge base, and as best I

recall the conversation with Scott Baker, the factory encourages the

"all or none" on speed brake deployment, but I too have a momentary "on"

for the deploy side and will probably count in my head over having a

gauge showing degree of deployment, but that's a good idea.

I also asked SB, and I would guess many have before me, on the notion

about lessor angle ought to mean higher speed limit.  Baker declined to

speculate, and added a warning to me about the panel going thru the prop

if the envelope was pushed beyond tolerance.  He did mention no attempt

was made by Velocity to test the high end of the speed range for the SB.

As I recall it he said that they decided 110 was safe and pegged it at

that.  ...or you might say a traffic pattern speed control device and

not designed for arrival descent use, or ATC requests to increase rate

of descent.

Terry

-----Original Message-----

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On

Behalf Of Paula & John Schoorl

Sent: Thursday, October 12, 2006 12:50 AM

To: Velocity Aircraft Owners and Builders list

Subject: Re: REFLECTOR: barn door speed brake

Terry:

Too add a little more info to Craig's reply about our XL-5FG with speed

brake:

Our max extension angle is about 75 degrees.  Chap 14 recommends not to

exceed 60 degrees.  How we ended up that way was we converted to the

cutdown keel halfway through the build and had to adjust our actuator

position to make it work.  It resulted in more extension angle than we

originally had. It also resulted in the actuator being installed in a

nearly vertical position which makes for a not very good load path from

door through actuator to keel.  On my to do list is to do the math and

figure what loads our actuator is seeing in our configuration versus the

book installation.

Our test pilot likes to fly his final approach with the speed brake

extended so he can keep more power in and have better engine response.

I tried the same technique but was not very comfortable with it and my

landings showed that.  I went back to flying without it like I was

primarly taught at the factory and my landings improved greatly.  Once I

am more comfortable in the airplane I will probably go back and

experiment with the speed brake some more, especially to shorten landing

distance.

As a side note to the discussion about rapid descents with gear or

brakes

extended:  The factory airplane wires the speed brake so it is either

fully extended of fully retracted.  I assume this air load on the door

and into the actuator and keel is what drives the 110kts speed brake

limitation. Craig and I wired our speed brake so the brake only extends

while you hold the switch down so we can extend to any angle we want by

how long we hold the switch (we have a position indicator on the panel).

Flip the switch up and the brake retracts completely for a go-around, in

case your wondering. While I'm figuring out loads on the brake, I also

intend to look at whether I can get away with a shallower speed brake

angle at a higher speed than 110 and get the benefit of the drag for a

higher rate of descent.  Thats an engineering problem for down the road

if I don't convince myself its a bad idea before then.

Hope that wasn't too much information....

John Schoorl

XL-5FG

Palmdale, CA

-----Original Message-----

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On

Behalf Of Terry Miles

Sent: Wednesday, October 11, 2006 1:31 PM

To: 'Velocity Aircraft Owners and Builders list'

Subject: Re: REFLECTOR: barn door speed brake

Thanks you guys.  ...and thanks Jorge.  The only one I could half way

measure looked to be between 55 to 60. Terry

-----Original Message-----

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On

Behalf Of Craig and/or Denise Woolston

Sent: Wednesday, October 11, 2006 8:32 AM

To: 'Velocity Aircraft Owners and Builders list'

Subject: Re: REFLECTOR: barn door speed brake

I'd say our extension angle is around 60 degrees.  I honestly can't

remember right now if the manual said to limit it or not.  The test

pilot landed with it down every time, but I haven't used it yet.

Craig

XL-5FG Flying in Palmdale, CA

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