REFLECTOR: barn door speed brake

Chuck Jensen cjensen at dts9000.com
Mon Oct 9 08:23:21 CDT 2006


A strong reason for a 500fpm planned descent is efficiency and economy.
We spend a lot of fuel/speed/time to gain altitude.  It's a terrible
waste to not turn that 'potential energy' into higher speed and reduced
fuel consumption during descent.  If VFR, a 200-300 fpm descent rates
seems to be the most productive.  If IFR, unless ATC puts us in a
squeeze, we can work with a 500 fpm descent, which is still pretty
efficient.
 
In contrast, throw out the barn door for a rapid descent and that long
slow climb and 100LL liquid gold disappears as turbulent drag with no
gain in speed or economy.
 
Chuck Jensen 
  

	-----Original Message-----
	From: reflector-bounces at tvbf.org
[mailto:reflector-bounces at tvbf.org] On Behalf Of Richard J. Gentil
	Sent: Monday, October 09, 2006 8:54 AM
	To: Velocity Aircraft Owners and Builders list
	Subject: Re: REFLECTOR: barn door speed brake
	
	
	I would think that unpressurized, you climb as fast as you want
but you come down on average, at 500fpm. Much more then that and you
start hurting the Pax ears. Most of the time I will start screaming for
lower a couple minutes before I end up at the 2 minutes from destination
for every 1,000ft I am AGL.
	
	Since I have yet to fly a Velo, anyone know in an SE RG what
speed indicated you hit when you keep cruise power (65%) and a 500fpm
descent rate?
	
	Richard
	
	P.S. Scott, I never thought about the fact, wing speed breaks
also destroy lift, not an option.
	
	Chuck Jensen wrote: 

		It would be nice to extend gear above 110 kts, though
I'm sure some have done so and I've yet to hear of anyone
slicing-n-dicing their departing gear doors.  The gear door extension
speed for the Velocity may be much like the Vne....it's a number, and
I've not heard conclusive evidence that it is anything but just a
number, so it may be a suggestion, not a limit.
		 
		As far as shock cooling of the engine, Scott, if you're
descending 2000 fpm in the Centurion and you're not shock cooling the
engine, exactly how fast did you intend dive the Velo such that you
could shock cool the engine?  I thought that OWT had been put to bed,
unless you're flying a radial or a couple other odd ball engines.  If we
reduce MP a few inches and point it down with the gear tucked, we might
want to watch Vne, especially in turbulence. but engine cooling can be
put way down the list.
		 
		As far as ATC giving you a slam-dunk approach, that can
be solved with one word, "unable".  However, as Ken reported, the speed
board does seem to cushion the nose gear 'plop' on touch-down...now that
would be appreciated!

		Chuck Jensen 
		  

			-----Original Message-----
			From: reflector-bounces at tvbf.org
[mailto:reflector-bounces at tvbf.org] On Behalf Of Scott Derrick
			Sent: Sunday, October 08, 2006 5:33 PM
			To: Velocity Aircraft Owners and Builders list
			Subject: Re: REFLECTOR: barn door speed brake
			
			
			What's really needed is a high speed speed
brake.  The current 110 knot extension speed severely limits its
usefulness.
			
			 The descent from altitude at cruise speed is
where our airplane can bite us.  If the air is turbulent or ATC would
like a hurry up descent the only option is the pull the throttle and
shock cool the engine. I fly a Centurion that has a 165 knot gear
extension speed with 200 knots after its deployed.  Descending is a
breeze, throw the gear out and your descending at 1500 ft per minute
with no increase in airspeed and you just leave the throttle alone,
reduce 3 or 4 inches of manifold pressure and your descending at 2000 ft
per minute and the engine cools down nice and slow...
			
			Scott
			
			Scott Baker wrote: 

				I don't know of anyone who has installed
speed brakes in the wings.
				This type of speed brake kills lift in
additional to being a drag device.
				Killing lift on the main wings invites a
deep stall when the aircraft gets slow.
				Installing an in-wing speed brake in the
canard guards against a deep stall, but it will also increase the stall
speed.  Again, not a good thing when the aircraft gets slow.
				I think a better approach is to look at
additional drag devices that deploy from the top of the fuselage - or -
maybe a panel that deploys from the nose gear area on RG models.
				SB

				----- Original Message ----- 
				From: Richard J. Gentil
<mailto:richard at naples-air-center.com>  
				To: Velocity Aircraft Owners and
Builders list <mailto:reflector at tvbf.org>  
				Sent: Sunday, October 08, 2006 2:54 PM
				Subject: Re: REFLECTOR: barn door speed
brake

				Scott,
				
				Has anyone done a speed brake system in
the Velo wings?
				
				Richard
				
				Scott Baker wrote: 

				Plan on installing a speed-brake in all
FG models, especially when operating with a fixed pitch propeller.
				SB

				
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