I just got off the phone with the A&P. I'm clipping your recommendation on Veturi Cleaning and we're going to do it tomorrow. I'll let you all know the results!
"Hoog"
Vacuum, Venturi's, pumps, & wing leveling.
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Re: Venturi's
No. I was asking what vacuum they are rated at. Its my understanding that venturis are rated by the amount of vacuum they can pull (probably assuming low air volume). If you have two 4" venturies, you can only expect to pull 4" of vacuum. If you had 10 4" venturies, you'd still only be able to pull 4" max vacuum (but at a higher volume).U2Hoog wrote:I'm not sure I understand your question. There are two venturi's mounted on the left hand side of the aircraft, which I believe were original equipment. Is that what you're asking?
I have one 8" venturi and have little trouble pulling 6" of vacuum.
Size venturi
Dale,
I don't know how to determine what size draw by looking at the Venturi. Where would I look to determine the capability of the draw? All I know is that before the installation of the new gyro's I was typically seeing around 6" in cruise flight. Now with the installation of the new gyros it's closer to 4" which isn't enough. The A&P is going to look at the regulator today to see if that's the problem, also going to do a cleaning of the venturi's as per another member's suggestion.
Hoog
I don't know how to determine what size draw by looking at the Venturi. Where would I look to determine the capability of the draw? All I know is that before the installation of the new gyro's I was typically seeing around 6" in cruise flight. Now with the installation of the new gyros it's closer to 4" which isn't enough. The A&P is going to look at the regulator today to see if that's the problem, also going to do a cleaning of the venturi's as per another member's suggestion.
Hoog
Venturis Revisited
Okay, here's the deal. We adjusted the regulator, and test flew. I need a little more adjustment, but at anything over 90 mph it pulls adequate air. I talked to the A&P and I want to adjust it a bit more so I can fly an approach at a constant 90 or 100 mph without being on the ragged bottom. The only problem with this is, apparently, at the high end, I can pull too much. (Yeah, like I cruise at 120mph). In any event, it seems to be working fairly well, and is definitely flyable. Now on to the fine tuning.
Oh, by the way
OBTW, the gyros I just put in are both RC Allen. One is an 11-D7 (heading gyro with hdg bug) and the other is a 22-7F (Attitude gyro with OFF flag). (I know, that's a bit over the top for a 99.5% VFR aircraft, but I'm preparing for that emergency some day. I figure an IFR pilot in a mostly VFR aircraft can probably make an emergency IFR descent if required - given the right tools. I'm hoping to over time continue to upgrade the plane to a "marginal IFR" which I define as a ceiling starting around 2000' and being around 1000' thick or so. We get that a lot up here in the NW, and it usually burns off in the afternoon, but can definitely slow you down on your departure if you need some altitude!
-
zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
vacuum
Hoog,I wouldn't worry too much about being on the "ragged bottom" of the green of your suction gauge while flying a 90 mph approach. I would assume an approach would usually take place after a period of cruise flight. Considering how long my gyro's take to spin down after parking,I think they'd be fine for a long time with the venturi's producing marginal suction at 90 mph before they spin down enough to be a problem. Even multiple full procedure approaches should be OK. I have 2 venturi's & modern DG & AH,at cruise they're pulling 5-1/2 to 6 inches (top of the green).
I'd be more concerned about taking off & getting into the clouds before the gyro's spin up. I imagine you'll be climbing at maybe 90 mph--again, marginal suction from the venturi's but this time they don't have any spin built up from cruise flight.
Of course,you always have the trusty old "needle,ball,airspeed" to fall back on.
Eric
I'd be more concerned about taking off & getting into the clouds before the gyro's spin up. I imagine you'll be climbing at maybe 90 mph--again, marginal suction from the venturi's but this time they don't have any spin built up from cruise flight.
Of course,you always have the trusty old "needle,ball,airspeed" to fall back on.
Eric
Venturi's & Needle Ball
Speaking of trustly needle ball, ever since the annual (when we moved the location of the needle-ball), the ball seems to be right of center when the aircraft is sitting still on the ground. Not sure why. Anyone have any ideas on that? Say the instrument wasn't put in exactly level, would that cause the problem?
Hoog
Hoog
-
zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
cock-eyed ball
Hoog,could be that your airplane's not sitting level on the ground in the roll axia. That's the case with mine. Check it by measuring from the ground up to the wingtips,while parked on a level spot. Mine's off by a couple inches,if I recall. A friend had the same situation with his Cessna,he fixed it by moving a shim from the top of the gear leg to the bottom at the gearbox. It doen't take much "off" at the gearbox to make a big difference at the wingtip.
Eric
Eric
Ball off center
Eric,
I'll give that a shot. Prior the new installations, it seemed fine. Ball centered, bat centered. Now the bat is fine, and the ball shows right. Strange, eh?
Hoog
I'll give that a shot. Prior the new installations, it seemed fine. Ball centered, bat centered. Now the bat is fine, and the ball shows right. Strange, eh?
Hoog
Re: Excellent input / emergency vacuum?
U2Hoog wrote:THanks! I'll keep a jug of distilled water down at the hangar and check after each flight. I may have the A&P adjust the output volts down just a little to 14 or 13.7 -- just as an experiment.
Since I have your ear, one more question. I'm currently using "dual venturi" as my source of vacuum. As I slowly migrate my mighty 1948 C-170 towards an emergency IFR capable machine, what do you recommend for use as vacuum air? I still have the stock engine.
There is a belt driven vac. pump available from Airborne.
Tim
The May 2002 Flypaper describes a 170 with "an alternator, and the alternator had another accessory drive pad on the back, to which was fitted a vacuum pump. Two accessories driven from one pad, an engine-driven vacuum pump, and an alternator in one slick mod." Does anyone have experience with this nifty sounding system?
Joe
51 C170A
Grand Prairie, TX
51 C170A
Grand Prairie, TX
-
zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
vacuum pump mod
The only vacuum pump mod I've seen for the C-145/O-300A is the one that's belt driven off the propeller flange & mounts in the co-pilot side nosebowl opening. Don't know if it works well,but man,it is U-G-L-Y!
The piggybacking off the alternator sounds like a much cleaner way to do it. But there isn't much room between my alternator & the firewall. I'd like to eyeball one of those piggyback installations & see how they did it.
Eric
The piggybacking off the alternator sounds like a much cleaner way to do it. But there isn't much room between my alternator & the firewall. I'd like to eyeball one of those piggyback installations & see how they did it.
Eric
Have never seen one of these, but for those interested the Flypaper list Dan Bedford as the STC owner - 352-666-2929 between 8:30-9:00 am.N1478D wrote:The May 2002 Flypaper describes a 170 with "an alternator, and the alternator had another accessory drive pad on the back, to which was fitted a vacuum pump. Two accessories driven from one pad, an engine-driven vacuum pump, and an alternator in one slick mod." Does anyone have experience with this nifty sounding system?