Rationale behind vacuum instruments

> Of course, one shouldn't forget that a usable vacuum "supply" was
> available without a pump when an external venturi was installed.
>
I was wondering how long it was going to take for someone to divulge the
REAL reason for vacuum instruments. External venturi tubes were the only
form of energy available to drive gyros on airplanes in the 30'3 and 40's
which had no electrical systems. After WW2 here were so many vacuum
instruments out there nobody had the courage to change.

Rod

IIRC, the FAA mandates a fully redundant electrical system (two
completely separate electric buses, each with its own alternator and
battery) before they'll allow you to run your primary gyros off
electric power. The added weight of such is often substantially more
than just a vacuum system alone.

Also, in almost every aircraft I've flown, Only the AG and DG run off
the vacuum system, while the Turn coordinator is electric. This way,
if either the vacuum or the electrical systems fail, you still have
enough of a partial panel to get you through a cloud layer, at the
very least.

"Thomas Borchert" <borchert_thomas@m> wrote in message
news:VA.00007454.1bb5410c@m...
>> This was written by someone obviously too young to have ever driven a
>> car with manifold vacuum powered windshield wipers and little to no
>> understanding of real engines.
>>
>
> This was written by someone running his AIRCRAFT engine at full
> throttle at the altitudes used by many of us. A throttle setting that
> will yield no usable manifold "pressure". A car is operated
> differently.
>
> --
> Thomas Borchert (EDDH)
>

The old cars didn't either. At idle the wipers would work at the normal
rate. When you accellirated from a stop they would either quit or slow to a
crawel. When you drop the throttle approaching your next stop, they would
waive franitically. It was really a hoot!

Robert M Gary wrote bs, bs, bs
Roy Epperson wrote bs, bs, bs
Deanwil wrote bs, bs, bs

What does it take for you people to understand that we are all sick and
tired of your pathetic attempts at humour/sarcasm/whatever you think it
is.
We are sick and tired of it.
Can you understand that?
You are not funny!

can we please please please have a respite from this ?

Thank you

Tony
--
Indiacharlieecho@m
Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE