Exocetid
Pre-takeoff checklist
I want to hook a vacuum pump up to my plane and run the vacuum-based systems (AI, DG, Brittain AP). Anybody doing this? Will a shop vac work or is something more/less powerful called for?
Hangar vacuum source
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KRyan
Pre-takeoff checklist
Don't know if this will get you where you need to be, but Harbor Freight sells little vacuum pumps for evacuating air conditioners and so on. The cheap ones are $99. I have a larger 2 stage one that was $150 that pulls 27 in/hg.
I used to have a Parker pump coupled to an 1800rpm 1/2hp electric motor as a vacuum source for various projects. Industrial/scientific vacuum pumps are bloody expensive and heavy, and don't pull the volume you need, they are meant to provide deep vacuum for scientific/industrial/chemical processes. Did I mention they are bloody expensive? There is a company that makes basically the same Parker rig with a DC motor to mount in a plane for stby vacuum, I've seen them in the front compartment of several PA-32s.
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With the volume he needs, he would have to put one of those on a huge tank and draw it down, then put a regulator and 1/2" hose and set it for 5". They are are high specific/low volume, where the system requires low specific/high volume.
Tom-D
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Tom-D
and zero cubic feet.
RJM62
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Geek on the Hill
Beyond the obvious play on words, are you saying the electric back up vacuum systems are not good? Because I do not know, I've never used one except to turn them on when doing someone's annual to function check it. I never used one in flight. The manifold vacuum back up systems aren't particularly nifty either. I think adding a Venturi in the induction prior to the carb/flow might be a better alternative.
RJM62
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Geek on the Hill
Beyond the obvious play on words, are you saying the electric back up vacuum systems are not good? Because I do not know, I've never used one except to turn them on when doing someone's annual to function check it. I never used one in flight. The manifold vacuum back up systems aren't particularly nifty either. I think adding a Venturi in the induction prior to the carb/flow might be a better alternative.
Nah, it was just a play on words. I was in a punny mood last night, and all of the forums I visited were victims.
Rich
A shop vac of decent size MIGHT have enough flow. I've seen guys try to run pipe organs on a small scale using a shopvac blower. (many organ ranks run on 4" or so of pressure, of course pipe organs need a lot more volume...the blower on my seven rank organ was probably 200x the size of your average aircraft pump).
murphey
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Pray tell, why? Ground training? Be very careful about damaging the equipment. Many years ago the cherokee was in for annual, and the AP/IA had a young novice, not even sure he was anything other than a family member helping for the summer. Young novice hooked everythingup wrong for the vacuum test, and the AP/IA wasn't paying attention. AP/IA started up the equipment, and I ended up,replacing all the vacuum instruments. Not as his shop, either.
Of course he denied young novice did anything wrong. Karma got him. Went out of business a year later.
Should point out this was also an official Garmin dealer who couldn't figure out why there was a problem with my SL30. All he had to do was read the manual to discover the problem with the original installation.
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jsstevens
How many CFM do they need? I rebuilt a shop vac many, many years ago. My instructions were "Find the biggest vacuum motor Grainger's sells and make it fit." That sucker would pull a 118" column of water. (So that's just under 1/3 of an atmosphere, ~ 4psi?). And move some air. But I don't know how many CFM it was.
While most gyros can run on pressure of vacuum, the system (regulators, etc...) isn't always set up to run that way so I'd be leary to just start blowing into the filter lines.
Exocetid
Pre-takeoff checklist
Why?
I have a Mooney and the AP (3-axis) as well as the retractable step, the AI and DG all run off vacuum. I want to play and troubleshoot.
No, one does not want to put pressure at all, no way, no how into a vacuum system.
4.5" Hg is what I need.
I have a Mooney and the AP (3-axis) as well as the retractable step, the AI and DG all run off vacuum. I want to play and troubleshoot.
No, one does not want to put pressure at all, no way, no how into a vacuum system.
4.5" Hg is what I need.
Easiest, cheapest way is to get a dry pump (I used one that a customer had changed at 500hrs) and a motor from Grainger. You can get the coupler socket or make one easily. 1/2hp works fine, 1/3rd would likely work.
Exocetid
Pre-takeoff checklist
Just a quick update.
I bought a vintage Garwin horizontal-dial DG off eBay that is the exact P/N that was in my Mooney the day it left the factory at KERR. Great desk item.
Anyway, I fired it up using a mini-shop vac and it ran fine. The mini-vac easily pulls and maintains 4.5" Hg or so. I don't know if it will run everything in the aircraft, but my guess is that it will.
I bought a vintage Garwin horizontal-dial DG off eBay that is the exact P/N that was in my Mooney the day it left the factory at KERR. Great desk item.
Anyway, I fired it up using a mini-shop vac and it ran fine. The mini-vac easily pulls and maintains 4.5" Hg or so. I don't know if it will run everything in the aircraft, but my guess is that it will.