Venturi tubes seem a great solution for IFR redundancy, but with the little
knowledge I have I am concerned about icing and drag penalty. I heard
somewhere that venturi type vacuum systems actually can ice up before the
airframe, thanks to the refrigerator-like expansion of air in the venturi
throat. Anyone know of ways to avoid this risk?
By way of intro., I am an avid Europa fan ("pre-Europa owner", please) who
has probably spent as many hours over the past two years dreaming about
building and flying one Mr. Shaw's little critters as I will (hopefully)
spend putting it together. It's a wonder I haven't been fired yet, all the
time I spend trolling your various websites (Tony K., of course, gets a
special mention). My current hope is to come back from Oshkosh next August
with a reason to spend a lot more time in the garage.
BTW, any Europa builders/owners in the US mid-Atlantic/DC area? I'd love a
chance to see one up close.
Joshua D. Fitzhugh
Williams, Mullen, Clark & Dobbins
900 17th St., NW, Suite 700
Washington, DC 20006
(202) 293-8129
jfitzhugh@wmcd.com
> -----Original Message-----
> From: Robert L. Nuckolls, III [SMTP:nuckolls@aeroelectric.com]
> Sent: Thursday, September 28, 2000 7:32 PM
> Subject: Re: Vacuum System
>
> Just a passing thought....will check my sources of replacement 12 volt
> vacuum
> motors used in motorhome central vacs, I know the until is about 80% more
> inches of vacuum then needed, but the motor does draw a fair amount of
> current at 14
> volts dc.. Perhaps using an IC regulator to reduce the voltage to around
> 8
> volts would bring the current to an acceptable level and enough vacuum.
> "TBO" for the brushes is rated 300-500 hours.
>
> I used to build electrically driven standby vacuum systems . . . they
> are NOT as dependable as an engine driven vacuum system . . . this is
> why they were popularized as a standby. It sat in the airplane unused
> until needed. The most dependable is a venturi . . . no moving parts.
> Harder to de-ice tho. Given that one's #1 mission upon encountering
> ice is to get out of ice, then perhaps de-ice isn't that important.
>
> See latest issue AOPA pilot where a pilot writes about an instrument
> course he took. The goal was to get him rated in 10 days. The first
> thing
> the instructor did was cover up the attitude gyro saying, "we won't
> need this."
>
> I used to fly shotgun for a co-worker's instrument proficiency
> work . . . he would cover up BOTH gyros and we'd go out to shoot
> approaches to minimums in the typcial KS bumpy crosswinds. And by
> the way, this was NOT a "no gyro" approach using timed turns from
> the ground. We went out at lunch time to fly Mid Continent Airport
> mixed in with all the big guys and totally on his own. He'd
> nail those two needles together and track them right down to the
> runway every time. Flying IFR with gyros is not difficult . . .
> it's just a different way of doing it. Doing it well gives you
> more options about equipment expectations and puts the odds of
> living to fly another day decidedly in your favor.
>
>
>
> Bob . . .
> --------------------------------------------
> ( Knowing about a thing is different than )
> ( understanding it. One can know a lot )
> ( and still understand nothing. )
> ( C.F. Kettering )
> --------------------------------------------
> http://www.aeroelectric.com
>
>
>
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