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BVM/UP retract valves
Hi,
I always used UP valves when my plane had doors and BVM valves when they didn't. I know if you use a BVM valve with doors you have to use a button valve to trigger the doors, which seems like another place to get a leak, not to mention setting up the button valve. I was wondering if the BVM system has any advantages over the UP valves. Thanks, Jon |
RE: BVM/UP retract valves
Jon,
You don`t have to use a button valve with BVM. You can set up two seperate bvm valves hooked up to a sequencer which will control the door operation. V.. |
RE: BVM/UP retract valves
Hi::)
But, why you no want use the button valve. It is more cheap that another valve and sequencer, and more easy for install, not is necesary programing. Best regards from Spain.;) Carlos. _____________________________ http://cmjets.blogspot.com/ |
RE: BVM/UP retract valves
I set up the BVM valve and servo, so when the valve is in full stroke / gear retracts, the servo still moves "over center" then pushes the button valve to close the doors. you do need to use servo speed in the TX to slow the servo down so that it gives time for the gear to come up before the button is pressed. this saves a sequencer / servo.
i have found the BVM valves top be pretty much bullet-proof. Kirk |
RE: BVM/UP retract valves
Hi Jon
On my Bandit I have been using the standard BVM valve, with a button valve to close the doors, and a servo slow function to sequence it all. This has worked perfectly for three years now, and is the simplest system I have come across. I used to ue a UP valve and found it was a bit fiddly to set up, but once it was set up itworked fine. Roger |
RE: BVM/UP retract valves
ORIGINAL: roger.alli I used to ue a UP valve and found it was a bit fiddly to set up, but once it was set up itworked fine. Roger Hi Roger, can you share with us the best way to setup the UP valve? is there a danger while setting it up that the doors close too soon and get damaged by the retract when coming down? thanks, V. |
RE: BVM/UP retract valves
Problem with the button valve is that it relies on the nose gear leg fully compressing the button valve.
If it doesn't and the button valve is half depressed, air will leak, then you cant get your gear down! |
RE: BVM/UP retract valves
ORIGINAL: bidrseed2 Problem with the button valve is that it relies on the nose gear leg fully compressing the button valve. If it doesn't and the button valve is half depressed, air will leak, then you cant get your gear down! Steven |
RE: BVM/UP retract valves
Hi V,
The way I setup the UP valves is: disconnect the cylinders from the doors, activate the valve and, as the gear goes up, watch when the door cylinders start to retract and adjust the needle valves to get the timing correct. After you have it setup that when the gear is retracted, then the doors close. Hook up the cylinders to the door and fine tune the timing. I've found that the settings of UP valves, as setup at the factory, are usually pretty close. BRG, Jon |
RE: BVM/UP retract valves
One problem I have experienced with the button method is door interference with the retracting gear. Because the door looses pressure to the "open" side as soon as the main valve moves, air loads can cause the door to close slightly and contact the retracting gear. This has only happened to me with certain doors on certain jets and it can sometimes be corrected by tightening the hinges on the door, making them less likely to blow closed.
In other cases, such as my Rafale with it's 5 sequencing gear doors, it's easier to just use two valves and an electronic sequencer like the Mini Hobby. Plus I like the ablility to manually open the doors and/or retract the gear any time I want. Craig |
RE: BVM/UP retract valves
ORIGINAL: vasek ORIGINAL: roger.alli I used to ue a UP valve and found it was a bit fiddly to set up, but once it was set up itworked fine. Roger Hi Roger, can you share with us the best way to setup the UP valve? is there a danger while setting it up that the doors close too soon and get damaged by the retract when coming down? thanks, V. The only issue I had with the UP value was getting the retracts to move nice and slow. I probably should have left it at the factory setting as Jon said, instead of tinkering with it, but I like my gear to operate slow rather then slam/slam. The vlave has tiny little fiddly adjusters to control the airflow, (like restrictors), and these took a bit of time to get right. If I set he gear up speed too slow, the doors would sometimes close early and colide with the wheel/leg, but once I got the speed right, no problem, and never had a wheels up landing due to that valve. I think they are good valves. Roger |
RE: BVM/UP retract valves
ORIGINAL: CraigG One problem I have experienced with the button method is door interference with the retracting gear. Because the door looses pressure to the ''open'' side as soon as the main valve moves, air loads can cause the door to close slightly and contact the retracting gear. This has only happened to me with certain doors on certain jets and it can sometimes be corrected by tightening the hinges on the door, making them less likely to blow closed. In other cases, such as my Rafale with it's 5 sequencing gear doors, it's easier to just use two valves and an electronic sequencer like the Mini Hobby. Plus I like the ablility to manually open the doors and/or retract the gear any time I want. Craig Craig, I had the exact problem with my Tam 16, because the door cylinders dump the "down air" and relax when the gear is commanded up. The doors were hanging on the main gear and jamming as they retracted. It only took one phone call and $450.00 to Dreamworks to solve all my problems !!!! Great valve !!!!! Good luck !!!! Danno |
RE: BVM/UP retract valves
ORIGINAL: rcjetsaok Craig, I had the exact problem with my Tam 16, because the door cylinders dump the ''down air'' and relax when the gear is commanded up. The doors were hanging on the main gear and jamming as they retracted. It only took one phone call and $450.00 to Dreamworks to solve all my problems !!!! Great valve !!!!! Good luck !!!! Danno I agree that the EV5 is a fantastic unit (I used one on my Viper Jet). Guess I'm just old-fashioned because I like to see the valves/mechanisms controlling my gear/doors/brakes etc.. and be able to move and adjust them manually. I never knew what was going on inside that box, how it worked or what to do when it didn't. But then again, I still use a slide rule.;) Craig |
RE: BVM/UP retract valves
ORIGINAL: CraigG ORIGINAL: rcjetsaok Craig, I had the exact problem with my Tam 16, because the door cylinders dump the ''down air'' and relax when the gear is commanded up. The doors were hanging on the main gear and jamming as they retracted. It only took one phone call and $450.00 to Dreamworks to solve all my problems !!!! Great valve !!!!! Good luck !!!! Danno I agree that the EV5 is a fantastic unit (I used one on my Viper Jet). Guess I'm just old-fashioned because I like to see the valves/mechanisms controlling my gear/doors/brakes etc.. and be able to move and adjust them manually. I never knew what was going on inside that box, how it worked or what to do when it didn't. But then again, I still use a slide rule.;) Craig |
RE: BVM/UP retract valves
ORIGINAL: bcovish ORIGINAL: CraigG ORIGINAL: rcjetsaok Craig, I had the exact problem with my Tam 16, because the door cylinders dump the ''down air'' and relax when the gear is commanded up. The doors were hanging on the main gear and jamming as they retracted. It only took one phone call and $450.00 to Dreamworks to solve all my problems !!!! Great valve !!!!! Good luck !!!! Danno I agree that the EV5 is a fantastic unit (I used one on my Viper Jet). Guess I'm just old-fashioned because I like to see the valves/mechanisms controlling my gear/doors/brakes etc.. and be able to move and adjust them manually. I never knew what was going on inside that box, how it worked or what to do when it didn't. But then again, I still use a slide rule.;) Craig Bob-O, Your still useing your Big Chief stone tablet and #2 Chisle !!!!!!![X(]:D:D Danno |
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