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Pete: You wrote: "When I restored the Coupe I read somewhere that it was imperative that I use the original suction line because of the large internal diameter." I think: There was no such think as an original suction line on a Coupe , Maybe the later Alons or Mooney had been delivered with vacuum instruments, but even that I doubt. >From what I have learned about venturies is that you experiencing the right behavior, full suction power is achieved at speeds around 100 MPH. This is another downside of using venturies to generate the suction for your instruments besides adding drag, it's speed dependent. Without wanting to start another discussion on whether or not to have Gyros in your Coupe, but knowing that we fly VFR only, my brother and I removed the Gyro installation on his Coupe (DG & HZ) and left the small ventury for the T&B. That should be sufficient for judging turns in low vis. We won payload and less drag by giving up a almost nothing , since we will not fly IFR, or even plan to do so . Hartmut Pete Thomson wrote: > ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- > > > > ----- Original Message ----- > From: Pete Thomson > To: Coupetech > Sent: 04/21/2003 7:25:33 PM > Subject: [COUPERS-TECH] Suction > Hi Coupers, Alaska Pete here. Fantastic weather up here, 23 > hours total for the past 2 weekends, smooth and clear, good > to be back in the air. When I restored the Coupe I read > somewhere that it was imperative that I use the original > suction line because of the large internal diameter. Well, I > did so and even purchased a new 14" suction venturi from > Aircraft Spruce. The suction is much better with the new > venturi, but still not good enough. It would seem to me that > I would get better suction with the new lines that have the > same OD but a smaller ID. Does this make sense to you guys > and gals? The venturi is the correct distance from the > fuselage and the plane is not flying in a slip. I am > operating a DG and AH and a suction gauge. The suction at 90 > MPH or less is under 4.5 but after 100 MPH it is right up > there. I am still using the old line with the large ID and > thin walls, however I am tempted to switch to the smaller > ID. Any ideas would be appreciated. I realize I could change > it and see if it worked but it is a real bear getting to the > fittings behind both instruments because of the header tank, > so I am looking for input,thanks,PeteThe information > contained in this message may be confidential and is > intended for addressee only. Any unauthorized use, > dissemination of the information, or copying of this message > is prohibited. If you are not the intended addressee, please > notify the sender immediately and delete this message. > Have a great day!!! > > ========================================================================== ==== > To leave this forum go to: http://ercoupers.com/lists.htm > Search the archives on http://escribe.com/aviation/coupers/ > > > > ========================================================================== ==== To leave this forum go to: http://ercoupers.com/lists.htm Search the archives on http://escribe.com/aviation/coupers/
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