Air flow rate control
05-27-2008, 07:34 PM
#1
Air flow rate control
What mechanisms are you guys using for flow rate control (not pressure - just rate) for retracts, gear doors, etc ?
I'm rigging 11 gear doors on my Jag just now, trying to control rates not only to avoid bang-bang actuation, but also to ensure that one door opens slightly slower than another so that they don't hit each other, etc.
Robart restrictors have their uses, but aren't quite up to what I want here. I tried clippard valves like the one shown below, but all of the useful control for my application is in the last 1.5 degrees of the many-turn needle, so it just isn't fine enough. Old fashioned mechanisms like using a wheel collet to clamp down and retsrict airlines have similar problems in that the control is too rough.
Any good ideas and/or product out there ?
Gordon
05-27-2008, 07:53 PM
#2
RE: Air flow rate control
hard as this sounds to do, it does work.
brass tube, electrical grade solder, and a set of fine numbered drill bits.
you have 2 areas of restriction to work with, length of restriction and diameter of hole.
takes patience, but worth the effort.
brass tube, electrical grade solder, and a set of fine numbered drill bits.
you have 2 areas of restriction to work with, length of restriction and diameter of hole.
takes patience, but worth the effort.
05-27-2008, 09:29 PM
#3
RE: Air flow rate control
ORIGINAL: Gordon Mc
What mechanisms are you guys using for flow rate control (not pressure - just rate) for retracts, gear doors, etc ?
I'm rigging 11 gear doors on my Jag just now, trying to control rates not only to avoid bang-bang actuation, but also to ensure that one door opens slightly slower than another so that they don't hit each other, etc.
Robart restrictors have their uses, but aren't quite up to what I want here. I tried clippard valves like the one shown below, but all of the useful control for my application is in the last 1.5 degrees of the many-turn needle, so it just isn't fine enough. Old fashioned mechanisms like using a wheel collet to clamp down and retsrict airlines have similar problems in that the control is too rough.
Any good ideas and/or product out there ?
Gordon
What mechanisms are you guys using for flow rate control (not pressure - just rate) for retracts, gear doors, etc ?
I'm rigging 11 gear doors on my Jag just now, trying to control rates not only to avoid bang-bang actuation, but also to ensure that one door opens slightly slower than another so that they don't hit each other, etc.
Robart restrictors have their uses, but aren't quite up to what I want here. I tried clippard valves like the one shown below, but all of the useful control for my application is in the last 1.5 degrees of the many-turn needle, so it just isn't fine enough. Old fashioned mechanisms like using a wheel collet to clamp down and retsrict airlines have similar problems in that the control is too rough.
Any good ideas and/or product out there ?
Gordon
I got control valve that similar.
Give me a call and we can go over the installation. Maybe 2 brain put together can come up good way to do it.
05-27-2008, 11:11 PM
#4
RE: Air flow rate control
Gordon try the Clippard MNV 1K, it is EXTREMELY precise. I use them on the gear doors of my F4 to do exactly what you are trying to achieve. Since set up years ago they have never needed adjustment.
Regards, David,
Regards, David,
05-28-2008, 01:58 AM
#5
RE: Air flow rate control
Gordon,
I use the SMC In-line One-touch Speed Controller Fitting for my gear. I use two for the gear, works great. They can also be used for gear doors. Catalog link below, see page 7:
http://www.smcetech.com/CC_catalogs/smc/pdf/AS.pdf
Ken
I use the SMC In-line One-touch Speed Controller Fitting for my gear. I use two for the gear, works great. They can also be used for gear doors. Catalog link below, see page 7:
http://www.smcetech.com/CC_catalogs/smc/pdf/AS.pdf
Ken
05-28-2008, 08:48 AM
#7
RE: Air flow rate control
Hey David - do you happen to know of a clippard part # for the female-threaded barb that the valve requires ? I know I can use the regular 11752-2 male-threaded barb for the female port in the vave, but I can't find the equivalent part of the opposite sex. Tried calling clippard but no response - they may not be open yet.
-
OK - got it. In case anyone else is interested, the part #s for the female threaded barbs are:
http://www.clippard.com/store/displa...ku=11752-2-PKG for 1/16" barb
http://www.clippard.com/store/displa...ku=11752-4-PKG for 1/8" barb
-
OK - got it. In case anyone else is interested, the part #s for the female threaded barbs are:
http://www.clippard.com/store/displa...ku=11752-2-PKG for 1/16" barb
http://www.clippard.com/store/displa...ku=11752-4-PKG for 1/8" barb
05-28-2008, 01:43 PM
#8
My Feedback: (1)
RE: Air flow rate control
Cyclinder control 101, the proper way to control a cyclinder is by restricting the atmospheric exit air side of the cyclinder and not limiting the inlet flow, this takes a check valve built internally into the valve and proper orientation of the check and needle restriction. this will give repeatable results and one would be needed on both sides.
By using orifice type hole restrictions your basically limiting air "in" on one direction and limiting atmospheric air "out" in the other direction for some basic weird compromise. Where this will show up is if you flip your model on the side or upside down where the gear load works in conjunction with gravity, you will have a whole nutha set of speeds. Inflight airpressues could drive you nuts.
Also air is very compressable and we move very little of it and that is why the mixed reviews of succes with flow controls on the valve itself, its really best to be as close the the cyclinder barb as possible, Gordon this alone will change your first clippard results.
I can buy inline restrictors of .001" drilled increments with any hose barb size needed. When differing speeds in both directions are not needed, one on each side gets the job done retracts only but does exhibit the slow creep movement.
By using orifice type hole restrictions your basically limiting air "in" on one direction and limiting atmospheric air "out" in the other direction for some basic weird compromise. Where this will show up is if you flip your model on the side or upside down where the gear load works in conjunction with gravity, you will have a whole nutha set of speeds. Inflight airpressues could drive you nuts.
Also air is very compressable and we move very little of it and that is why the mixed reviews of succes with flow controls on the valve itself, its really best to be as close the the cyclinder barb as possible, Gordon this alone will change your first clippard results.
I can buy inline restrictors of .001" drilled increments with any hose barb size needed. When differing speeds in both directions are not needed, one on each side gets the job done retracts only but does exhibit the slow creep movement.
05-28-2008, 02:03 PM
#9
RE: Air flow rate control
ORIGINAL: c/f
Cyclinder control 101, the proper way to control a cyclinder is by restricting the atmospheric exit air side of the cyclinder and not limiting the inlet flow, this takes a check valve built internally into the valve and proper orientation of the check and needle restriction. this will give repeatable results and one would be needed on both sides.
Cyclinder control 101, the proper way to control a cyclinder is by restricting the atmospheric exit air side of the cyclinder and not limiting the inlet flow, this takes a check valve built internally into the valve and proper orientation of the check and needle restriction. this will give repeatable results and one would be needed on both sides.
Also air is very compressable and we move very little of it and that is why the mixed reviews of succes with flow controls on the valve itself, its really best to be as close the the cyclinder barb as possible, Gordon this alone will change your first clippard results.
I can buy inline restrictors of .001" drilled increments with any hose barb size needed. When differing speeds in both directions are not needed, one on each side gets the job done retracts only but does exhibit the slow creep movement.
Gordon
05-29-2008, 08:49 PM
#10
RE: Air flow rate control
Sorry, Gordon, no. I have the parts I think you mean but they dont have a part number on it. My Google directs me to the Australian Clippard web site , yours in the US may well show the part. Regards, David.
06-21-2008, 03:33 AM
#14
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RE: Air flow rate control
All these you have listed are large and heavy.
Try these guys.
[link=http://www.westgroup.co.uk/]West home[/link]
More specific
Air Logic - Accessories Catalogue
[link=http://www.westgroup.co.uk/catalogue.asp]Airlogic[/link]
Download Air Logic - Accessories Catalogue pdf
This is the range i use, look at the restrictors.
Not just the restrictors but this site is a Gem for just about anything for model pneumatics
Paul
06-22-2008, 12:51 AM
#15
RE: Air flow rate control
Paul,
Thanks for sharing these links; I really like the inline gauge from The West Group. I might look into buying one of those in the future.
As for the orifice restrictors, I currently use two Airlogic inline barbed orifice restrictors in my Rafale. Beware; you need to handle them with care as they break very easy when pressing the tubing onto the barbs. The body also has a part line and can crack with to much pressure during tubing application. Look carefully at the PSI rating for these as well, in some cases they won’t handle the pressure we’re putting into our jet pneumatic system(s).
Ken
Thanks for sharing these links; I really like the inline gauge from The West Group. I might look into buying one of those in the future.
As for the orifice restrictors, I currently use two Airlogic inline barbed orifice restrictors in my Rafale. Beware; you need to handle them with care as they break very easy when pressing the tubing onto the barbs. The body also has a part line and can crack with to much pressure during tubing application. Look carefully at the PSI rating for these as well, in some cases they won’t handle the pressure we’re putting into our jet pneumatic system(s).
Ken
02-09-2009, 10:11 AM
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RE: Air flow rate control
ORIGINAL: tamjets
Gordon,
I got control valve that similar.
Give me a call and we can go over the installation. Maybe 2 brain put together can come up good way to do it.
ORIGINAL: Gordon Mc
What mechanisms are you guys using for flow rate control (not pressure - just rate) for retracts, gear doors, etc ?
I'm rigging 11 gear doors on my Jag just now, trying to control rates not only to avoid bang-bang actuation, but also to ensure that one door opens slightly slower than another so that they don't hit each other, etc.
Robart restrictors have their uses, but aren't quite up to what I want here. I tried clippard valves like the one shown below, but all of the useful control for my application is in the last 1.5 degrees of the many-turn needle, so it just isn't fine enough. Old fashioned mechanisms like using a wheel collet to clamp down and retsrict airlines have similar problems in that the control is too rough.
Any good ideas and/or product out there ?
Gordon
What mechanisms are you guys using for flow rate control (not pressure - just rate) for retracts, gear doors, etc ?
I'm rigging 11 gear doors on my Jag just now, trying to control rates not only to avoid bang-bang actuation, but also to ensure that one door opens slightly slower than another so that they don't hit each other, etc.
Robart restrictors have their uses, but aren't quite up to what I want here. I tried clippard valves like the one shown below, but all of the useful control for my application is in the last 1.5 degrees of the many-turn needle, so it just isn't fine enough. Old fashioned mechanisms like using a wheel collet to clamp down and retsrict airlines have similar problems in that the control is too rough.
Any good ideas and/or product out there ?
Gordon
I got control valve that similar.
Give me a call and we can go over the installation. Maybe 2 brain put together can come up good way to do it.
Also it is retracting (up) to fast, bang bang. I have a medium size air tank, 100 psi. Getting about 3-5 cycles by then the air pressure gauge is tell me that I still have around 82 psi. At that psi only one will go down and the other one stops at the rotating stage.
I am using a standard Futaba 3004 servo. Attached a picture of the set up. I have filled up to 100 psi and left it over night, by the morning (8 hrs) the air gauge showed me I only had about 10 psi.
This is my first try with retracts, so my experience from 1-10 is maybe 0. Need help please.
Garthwood.
