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Roost Air Lounge => The Classroom => Topic started by: gibbo_335 on October 18, 2008, 12:28:01 AM

Title: Interesting question on Vacuum driven gyros
Post by: gibbo_335 on October 18, 2008, 12:28:01 AM
I had an interesting question thrown at me the other day, and  :-[ i couldn't answer it with any authority  :-\ SO I thought I'd throw it out to the experts  ::bow:: here in da coop  ;D  Here goes.....

Why do the manufacturers of non-electrically driven gyro instruments eg: AI and DG use vacuum and not pressure to drive the gyro?
Title: Re: Interesting question on Vacuum driven gyros
Post by: Rooster Cruiser on October 18, 2008, 02:56:33 AM
When gyroscopic instruments were initially developed for aircraft in the 1920's there were no electrical systems in most airplanes.  Engine driven pneumatic pumps (pressure or vacuum) were expensive and subject to failure.  The worst case scenario would be having a pressure pump fail while in flight.  When this would happen, not only would the pump have to be replaced, but pieces of the pump would be pushed into the gyros which would destroy them also.  The cheapest and most reliable means of powering gyros for instrument equipped airplanes was to install a venturi outside of the airplane which would create a source of vacuum pressure while in flight.  Then it became a simple matter of designing vacuum gyros to tap into the power source.  You could say this is another application of the KISS design principle (Keep It Simple, Stupid).

Not all pneumatic powered aviation gyros are vacuum driven.  Most pressurized piston engine aircraft designed for high altitude flight have pressure driven gyros if they do not have a dual electrical system.  When you are talking about flying above 20,000 feet in such very thin air, venturis and engine-driven pumps simply cannot supply a large enough pressure differential to allow vacuum gyros to work reliably.

As electrical systems became common in small airplanes, vacuum driven gyros were supplemented by electrically driven gyros to meet redundancy requirements for IFR flight.  In the 1960's and 1970's more reliable engine driven vacuum pumps became commonplace, replacing the older venturi-driven vacuum systems.  However, vacuum driven gyros remained in widespread use in GA aircraft up until EFIS systems began replacing them in larger aircraft in the 1980's and 90's and glass cockpits became the norm for most GA manufacturers in this decade.

I have left out a lot of details in order to keep this short.  You can find entire books that have been written on this subject if you look hard enough.  Best thing to check at the library would be the history of General Jimmy Doolittle and the Sperry Corporation, who together pioneered aviation gyro systems as we know them today.  General Doolittle was also credited with making the first flight solely by reference to instruments from takeoff to landing (!) in the late 1920's.  That is still an amazing feat when I think about it.

I think you can still find vacuum gyros in most glass cockpit airplanes that do not have a secondary electrical system.  They will be tucked away somewhere, whirring away as a backup to fall back on in the event you have a total electrical system failure. 

Now back to watching "Smokey and the Bandit" for me.   Hehe  ::cowboy::

RC
Title: Re: Interesting question on Vacuum driven gyros
Post by: G-man on October 18, 2008, 04:58:18 AM
When gyros were initially developed for aircraft in the 1920's
RC

See, now there ya go trying to make it all complicated-- I saw the word "Gyro", and immediately thought of the little Greek restaurant in downtown Pocatello that makes THE best gyro's.  ::whistle:: ::whistle:: ::drinking::
Title: Re: Interesting question on Vacuum driven gyros
Post by: Rooster Cruiser on October 18, 2008, 05:17:20 AM
When gyros were initially developed for aircraft in the 1920's
RC

See, now there ya go trying to make it all complicated-- I saw the word "Gyro", and immediately thought of the little Greek restaurant in downtown Pocatello that makes THE best gyro's.  ::whistle:: ::whistle:: ::drinking::

Ok G-man, you got me there!   ::knockedout::  Hehe.  I went ahead and edited my post for your benefit.   ::drinking::
Title: Re: Interesting question on Vacuum driven gyros
Post by: Oddball on October 18, 2008, 06:56:13 AM
AARRRRRRRGGGGHHHH GYROS!!!!!!!!!  ::eek:: ::unbelieveable:: ::banghead:: ::banghead:: ::banghead:: ::banghead:: ::banghead::
Title: Re: Interesting question on Vacuum driven gyros
Post by: G-man on October 18, 2008, 02:05:27 PM
Hmmmm.. Gyros.  ::whistle:: ::whistle::

(http://i76.photobucket.com/albums/j35/helokat/Gyro.jpg)
Title: Re: Interesting question on Vacuum driven gyros
Post by: 4X-NTY on October 18, 2008, 03:05:02 PM
Hmmmm.. Gyros.  ::whistle:: ::whistle::

(http://i76.photobucket.com/albums/j35/helokat/Gyro.jpg)

It's not kosher!!!
but sure looks tasty... (sorry about that,couldn't stop myself!)
Title: Re: Interesting question on Vacuum driven gyros
Post by: G-man on October 19, 2008, 03:49:21 AM
It's not kosher!!!

How can you tell?
Title: Re: Interesting question on Vacuum driven gyros
Post by: Oddball on October 19, 2008, 09:30:51 AM
Hmmmm.. Gyros.  ::whistle:: ::whistle::

(http://i76.photobucket.com/albums/j35/helokat/Gyro.jpg)

Am not into Avionics but i know one thing that aint no Ring Laser Gyro and there are no Gimbals....
Title: Re: Interesting question on Vacuum driven gyros
Post by: G-man on October 19, 2008, 01:30:50 PM
Am not into Avionics but i know one thing that aint no Ring Laser Gyro and there are no Gimbals....

Nope--Just your regular Gyro--hold the greens..
Title: Re: Interesting question on Vacuum driven gyros
Post by: 4X-NTY on October 19, 2008, 10:01:55 PM
It's not kosher!!!

How can you tell?

Easy,unless that white stuff is not a cheese.
The bible says "you won't cook a calf in it's mother milk",and they carried away saying that eating meat and milk together,you can't even cook them in the same pot,you need to wait two hours until you can eat the other.
By the way,fish is not milk,and pork is not kosher from a whole lot of reason that i don't have the time and the knowledge to explain them,personally,i think that pork sausages are better then the normal one,thank god for those Russians that sells pork!
Title: Re: Interesting question on Vacuum driven gyros
Post by: gibbo_335 on October 20, 2008, 05:04:20 AM
R/C you are a font of knowledge mate, thanks for that mate  |:)\

HA HA Gordie, thats the best kinda gyro to have on a flight  ::rofl::
Title: Re: Interesting question on Vacuum driven gyros
Post by: G-man on October 20, 2008, 03:42:39 PM
Easy,unless that white stuff is not a cheese.

White stuff is sour cream and the meat is NOT pork---its Lamb..
Title: Re: Interesting question on Vacuum driven gyros
Post by: 4X-NTY on October 21, 2008, 02:48:50 AM
Easy,unless that white stuff is not a cheese.

White stuff is sour cream and the meat is NOT pork---its Lamb..
i meant to say dairy products,and it doesn't really matter if it's pork or lamb,meat with dairy product are not allowed.
but please,i don't want to change the topic of this discussion to something not relative at all,so if you really want to know more,please let's make this discussion on a new topic,private messages or chat  :)
Title: Re: Interesting question on Vacuum driven gyros
Post by: Rooster Cruiser on October 21, 2008, 05:23:21 AM
Easy,unless that white stuff is not a cheese.

White stuff is sour cream and the meat is NOT pork---its Lamb..

G-man, I thought the white stuff was the Cucumber sauce.  I can't remember the name of it, but I guess it could be sour cream based... ::thinking::

Anyway... Gyros, Gyroscopes, and what constitutes Kosher all in one thread!  Man, what a strange group of posters we've got in here!  Hehe.   >:D
Title: Re: Interesting question on Vacuum driven gyros
Post by: G-man on October 21, 2008, 05:39:44 AM
G-man, I thought the white stuff was the Cucumber sauce.  I can't remember the name of it, but I guess it could be sour cream based... ::thinking::
Anyway... Gyros, Gyroscopes, and what constitutes Kosher all in one thread!  Man, what a strange group of posters we've got in here!  Hehe.   >:D

The sauce on the Gyro is prolly tzatziki sauce, you are right it is cucumber based, (Like Raita in indian cuisine). It is actually yogurt based not sour cream---my mistake.

Yep, we are a different bunch huh---I was actually just being an "ass", as usual.. ::whistle:: ::whistle:: I think I had had a martooni when I posted the pic, and ended up leaving it to see where it would go---never really thought we would hit the whole "Kosher" issue though.
Title: Re: Interesting question on Vacuum driven gyros
Post by: Rooster Cruiser on October 21, 2008, 05:55:38 AM
Not to worry Dude!  That's what I like about this forum... start off with a technical question and answer, and the thread ends up discussing tzatziki sauce and what is kosher.  Very informative, and quite often funny!   |:)\
Title: Re: Interesting question on Vacuum driven gyros
Post by: Oddball on October 21, 2008, 10:04:01 AM
 ::rofl:: ::rofl:: ::rofl:: and may it never end  ::drinking:: ::drinking:: |:)\
Title: Re: Interesting question on Vacuum driven gyros
Post by: Mike on October 21, 2008, 03:18:34 PM
Easy,unless that white stuff is not a cheese.

White stuff is sour cream and the meat is NOT pork---its Lamb..

G-man, I thought the white stuff was the Cucumber sauce.  I can't remember the name of it, but I guess it could be sour cream based... ::thinking::

Anyway... Gyros, Gyroscopes, and what constitutes Kosher all in one thread!  Man, what a strange group of posters we've got in here!  Hehe.   >:D

if it's original, it should be a Lamb/Beef mix with a Tzatziki sauce (sorry if I spelled that wrong, Airscorp) which should be a combination of
yogurt, cucumber, and garlic and is VERY VERY tasty !!!!
(*insert lip smacking, mouth watering smiley*)
 ;D
Title: Re: Interesting question on Vacuum driven gyros
Post by: Frank N. O. on October 21, 2008, 05:06:09 PM
From aircraft instruments to food, really far out! :D However everytime I look at that photo I can't help but think that the brown stuff really looks like what in danish is called "hunde høm-høm".

Frank
Title: Re: Interesting question on Vacuum driven gyros
Post by: Oddball on October 21, 2008, 05:07:49 PM
as long as there are no mushrooms on it ill give it a go.
Title: Re: Interesting question on Vacuum driven gyros
Post by: TheSoccerMom on October 21, 2008, 11:18:08 PM

 ::)                     ::)                     ::)

[Example #4,679 of Aviation Enthusiasts Who Have Serious ADD Problems......]

 :D

("Uhh, WHAT topic?  Huh?  Hey look, there's something shiny over there!!!")

 ;)
Title: Re: Interesting question on Vacuum driven gyros
Post by: Fabo on October 22, 2008, 12:21:20 AM
Are you guys crazy? You almost made me dress up and travel halfway through Prague on 2 20 AM...


Hmmm.... Gyros...

Must... Resist... Temptation....






D'oh! you get me there, I will just HAVE to get one tomorrow morning... thankfully one opened during daytime is only 5 minutes away...
Title: Re: Interesting question on Vacuum driven gyros
Post by: Oddball on October 22, 2008, 12:09:53 PM
I do have a ADD problem i cant do maths  ::whistle:: (there you go another subject change lol)
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