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Weird UP-3 valve problem

Old 11-29-2009, 11:02 PM
  #1  
acw
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Default Weird UP-3 valve problem

I bought Dantley, ex Raffy Chippy Ho. I did re-maiden the plane today and I'm pretty happy, except for a weird problem with the retract valve, which is an Ultra Precision UP-3 valve. Here are the symptoms along with all the relevant information.

- the plane has Tam's gear in it and 9 gear door cylinders.
- when the retract system is empty (no pressure) and after filling it to 100psi, the front gear won't go all the way up. It starts moving until about half way. At that point, I can feel a lot of air coming out the UP-3 valve itself. It sometimes bleeds all the air. After a few attempts, the gear goes up normally. Once it works, it keeps working until the air runs out completely.
- Sometimes, closing one door manually or forcing the gear up helps the system get out of this mode. Not sure.
- Each outlet (gear up, gear down, door up, door down) are T'ed together into one line. I wonder if maybe using one outlet for say the front gear and the other for the rear gear would help.

It appears there is some kind of abnormal pressure balance in the valve causing the air to escape instead of being applied to the retract cylinder. This appears to be caused by an empty (no pressure system) on the door cylinder side. I tried to change the needle setting for the main gear but that did not help.

Can an UP-3 valve drive 9 gear doors? Can you guys think of a fix?

Thanks for any suggestion.

Arnaud

Old 11-29-2009, 11:26 PM
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Ruizmilton
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Default RE: Weird UP-3 valve problem

Arnaud:

Probably the plunger needs to be lubricated, the friction is not allowing it to move al low pressures and a dry o-ring would leak air, there is a door on one of the sides and a small hole on the opposite side, remove the 2 screws on the perimeter of the door and with a properly thin piano wirewith a SMOOTH END, insert it through the hole on the opposite side and push the plunger and door out, watch out for the spool and spring, lubricate o-rings with silicone grease ONLY (Dow #55) and reinstall
Old 11-30-2009, 12:14 AM
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Default RE: Weird UP-3 valve problem

Could also be bleed-thru of the retract cylinder from one side to the other .. try some of the magic bvm thin lube .. inject in the airlines at the retract on both sides, and cycle it a bit. I've seen a few cases where a nosegear on a Kingcat did this for the first few cycles after sitting for a while .. cycle a few times with manual assist on the retraction and it's fine.

Dave
Old 11-30-2009, 02:39 AM
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Default RE: Weird UP-3 valve problem

Hi,

Un-tee everything. Send one outlet from the valve to one cylinder on the plane. You can tee-off at the cylinders to control multiple cylinders, but don't tee at the valve. Betcha that solves it.
Old 11-30-2009, 03:17 AM
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Default RE: Weird UP-3 valve problem

ORIGINAL: ww2birds

Could also be bleed-thru of the retract cylinder from one side to the other .. try some of the magic bvm thin lube .. inject in the airlines at the retract on both sides, and cycle it a bit. I've seen a few cases where a nosegear on a Kingcat did this for the first few cycles after sitting for a while .. cycle a few times with manual assist on the retraction and it's fine.

Dave
I was about to use BVM Thin Lube on a UP valve but called UP and was specifically told not to use it. Apparently it will eat away the seals in the valve. Use silicon spray if you need to lube the valve.

The bleeding problem is a common symptom when you have a leak through one of the gear or door cylinders. If you clamp off both sides of each cylinder (one at a time so it can take a while) you'll likely find your culprit.

Regards,

Jim
Old 11-30-2009, 05:34 AM
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Default RE: Weird UP-3 valve problem

Hi.
I have 9 of these valves so I can tell you I have a ton of experience with them.

First your UP valves are covered for life by Ultra Precision. It does not matter if a part fails from wear or if you damage the valve in a crash. You simply send it back and it is fixed free of charge!! Amazing. I have done this several times.

Next the leaks are usually caused by blow by in one of the gear or door cylinders. do the usual checks to determine which one then fix the problem.

However I do believe that these valves have some quirks. I get irregular sequencing or slow to react door at times and I can usually solve the problem by lubing the inner plunger as described above. In other cases I do believe that the valve needs to find its own equilibrium. For example if the air runs totally out of the system and I fill it back up and cycle the gear I get the 1/2 way up gear followed by the hissing air. I have found that If I push the gear up all the way by hand and let the hissing continue then just as the air pressure in the tanks get low the doors will close. Then filling the tanks again resumes 100% normal operation of the gears and doors. It will stay that way too as long as you don't let the system go to zero pressure again.

Hope this helps,
Dom
Old 11-30-2009, 08:29 AM
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Default RE: Weird UP-3 valve problem

Dom,

Interesting. Did not know that something so simple as a spool valve has so much "personality". I have 3 of them myself, and have always tracked down issues that seemed to be valve-related to be cylinder related. But I guess the valve has done spooky things for you. I'll keep that in mind. Are there any moving parts other than the spool itself, that is driven by the servo? I did not think there were, so the only odd thing that could really happen is some sort of plugged orifice .. but if there are hidden moving parts (the "inner plunger?") maybe that explains it. Seems to be the case when I read Arnaud's post and yours. Live + learn.

Jim,

thanks for the info re: BVM thin lube. I have only ever injected it at the cylinders, and it seems to work wonders for balky or leaky cylinders .. but once its in the system, I suppose if will eventually go everywhere. Good to know UP does not like the stuff. I do have some of the Dow 55 that I got from them a while ago that I use to lube the spools. I wonder if the o-rings in the cylinders (that are ok with BVM lube) and the o-rings in the valve are different .. e.g. rubber vs viton.

Shawn,

Why does it matter where the tees are?

Dave
Old 11-30-2009, 04:41 PM
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Default RE: Weird UP-3 valve problem

ORIGINAL: MaJ. Woody



However I do believe that these valves have some quirks. I get irregular sequencing or slow to react door at times and I can usually solve the problem by lubing the inner plunger as described above. In other cases I do believe that the valve needs to find its own equilibrium. For example if the air runs totally out of the system and I fill it back up and cycle the gear I get the 1/2 way up gear followed by the hissing air. I have found that If I push the gear up all the way by hand and let the hissing continue then just as the air pressure in the tanks get low the doors will close. Then filling the tanks again resumes 100% normal operation of the gears and doors. It will stay that way too as long as you don't let the system go to zero pressure again.

Hope this helps,
Dom
Arnaud, I've told you and Dantley this about UP3 and UP2 valves. EVERY SINGLE ONE I've ever owned has this type of quirkinesses, if you will. Change it out to an "ultra" valve from Todd at dreamworks and you won't have the quirkiness. There sounds to be NOTHING wrong with your (my old) valve.

If you have blow by or a leak somewhere, these valves will NEVER work perfectly. It it works after the first few times then it will continue to work, EVERY TIME. On a hornet there are 10 gear doors and it is painful to see them slam shut on the half retracted struts, YES, WE KNOW, but you may have to help the gear up the first few times, oh well. Its just how "it is". Yeah it sucks and we want an answer for EVERYTHING, but then some things are just quirky, and unanswerable by nature. Kinda like a "low RPM" off condition on a jetcat. LOL

Raf
Old 11-30-2009, 06:42 PM
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Default RE: Weird UP-3 valve problem


ORIGINAL: YellowAircraft

Hi,

Un-tee everything. Send one outlet from the valve to one cylinder on the plane. You can tee-off at the cylinders to control multiple cylinders, but don't tee at the valve. Betcha that solves it.
I don't understand at all, please, can you sketched?
I have the same issue with a Robart valve and I have checked every cylinder in ALL possibles positions and no leaks.[sm=confused.gif]

BR

Jesus
Old 11-30-2009, 10:05 PM
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acw
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Default RE: Weird UP-3 valve problem

Thanks for all the answers. This thread is *very* useful.

Raf, I have the same UP3 valve in my F-16. Granted, it has only 3 gear doors but it always works perfectly. I know my system in the Chippy Ho isn't leak free since it looses all air in about 1h. So maybe a leak from a cylinder could cause this. I agree that a dreamworks electronic valve would be the way to go but it would be a big change.

I'll try to troubleshoot some more and will report back. My plan is to pinch lines to isolate what cylinder might be causing this. I also have some BVM "magic lube" that I can try to use on the door cylinders and the gear.

Jesus, the valve has 2 outlets for each output (gear down, gear up, door open, door close). I have placed a T fitting to join the 2 outlets for each output. YellowAircraft is suggesting to remove all Ts and use one outlet for a subset of cylinders and the other one for another subset.  I might try that but that would be a lot of work and it is hard for me to understand why it would make a difference.

Thanks again for all the help and please keep the suggestions coming.

Arnaud
Old 11-30-2009, 11:38 PM
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Default RE: Weird UP-3 valve problem

I saw this happen with the Chippy Ho, Tam's F-18, and Tam's SM F-86 which all had UP-3s. It's really a small pain for the first cycle, but after that it works flawlessly the rest of the day.
Old 12-01-2009, 12:10 AM
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acw
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Default RE: Weird UP-3 valve problem

I still feel it is pretty annoying. I want to make sure the gear works every time and don't like having to perform a gear check before every flight. I'll get to the bottom of this or I'll switch to an electronic valve.

Arnaud

Old 12-01-2009, 12:30 AM
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Default RE: Weird UP-3 valve problem

I suspect the only way to completely solve the problem is go with a different valve.
Old 12-01-2009, 05:36 AM
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Default RE: Weird UP-3 valve problem

I cycle my gear before every flight as part of the preflight. You never know how that last landing has affected the gear no matter how soft it was. All it takes is just a little twist to cause a gear to hang up in the well. I want to be proactive about that.
Dom

Old 03-12-2019, 12:16 PM
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EUROSPORT JET IRELAND
 
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Hello
can you please help me, I have a UP3 valve but no instructions.
I would appreciate greatly if you could give me a Copy.
many thanks
Kind regards
John
Old 03-12-2019, 01:17 PM
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Jetpilot24
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Default

Originally Posted by acw
I bought Dantley, ex Raffy Chippy Ho. I did re-maiden the plane today and I'm pretty happy, except for a weird problem with the retract valve, which is an Ultra Precision UP-3 valve. Here are the symptoms along with all the relevant information.

- the plane has Tam's gear in it and 9 gear door cylinders.
- when the retract system is empty (no pressure) and after filling it to 100psi, the front gear won't go all the way up. It starts moving until about half way. At that point, I can feel a lot of air coming out the UP-3 valve itself. It sometimes bleeds all the air. After a few attempts, the gear goes up normally. Once it works, it keeps working until the air runs out completely.
- Sometimes, closing one door manually or forcing the gear up helps the system get out of this mode. Not sure.
- Each outlet (gear up, gear down, door up, door down) are T'ed together into one line. I wonder if maybe using one outlet for say the front gear and the other for the rear gear would help.

It appears there is some kind of abnormal pressure balance in the valve causing the air to escape instead of being applied to the retract cylinder. This appears to be caused by an empty (no pressure system) on the door cylinder side. I tried to change the needle setting for the main gear but that did not help.

Can an UP-3 valve drive 9 gear doors? Can you guys think of a fix?

Thanks for any suggestion.

Arnaud

Had the same issue with a 1/5th Skymaster F-86. You definitely have a bleed thru on one or more cylinders. Start by pinching off lines at the gear one at a time to isolate the culprit. Pinch off each airline for the gear up at each cylinder one at a time. You have to fix the bleed thru or the UP valve will not work correctlly

Joe Lewis
Kingtech
K-80, K-140, K-180
Owner
Old 03-12-2019, 10:03 PM
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Originally Posted by EUROSPORT JET IRELAND
Hello
can you please help me, I have a UP3 valve but no instructions.
I would appreciate greatly if you could give me a Copy.
many thanks
Kind regards
John
https://www.modelaviationproducts.co...ion-products/7
Old 03-13-2019, 06:50 AM
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Dave
thanks that was very helpful,
regards
​​​​​​​john

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