JMP air trap
03-03-2002 | 05:41 AM
#4
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Header vs air trap...
ishu4u,
True, a standard header tank can be used with a geometrically centered fuel pickup. The difference is the fabric membrane in the JMP and BVM "air trap" style tanks. As an air bubble appears in the header tank, the surface tension at the air bubble's surface causes the membrane to adhere to it. Since the clunk is inside the fabric, it is never exposed to air and should never be starved of fuel...
If a membrane-less fuel tank is used, David Gladwin recommends at least 14 oz in capacity. The reason not to use a 2 oz tank is that a geometrically centered pickup would be exposed to air after a bubble displaced only 1 oz of fuel. If a 14oz tank was used the likelihood of displacing 7oz of fuel with air is much less... A heli's piston engine can live with a bubble or two and keep running, unlike a turbine.
If $$$ is a problem
when purchasing a tank, Woketman is a good one to ask about making your own.:thumbup:
Later,
Kelly
True, a standard header tank can be used with a geometrically centered fuel pickup. The difference is the fabric membrane in the JMP and BVM "air trap" style tanks. As an air bubble appears in the header tank, the surface tension at the air bubble's surface causes the membrane to adhere to it. Since the clunk is inside the fabric, it is never exposed to air and should never be starved of fuel...
If a membrane-less fuel tank is used, David Gladwin recommends at least 14 oz in capacity. The reason not to use a 2 oz tank is that a geometrically centered pickup would be exposed to air after a bubble displaced only 1 oz of fuel. If a 14oz tank was used the likelihood of displacing 7oz of fuel with air is much less... A heli's piston engine can live with a bubble or two and keep running, unlike a turbine.
If $$$ is a problem
when purchasing a tank, Woketman is a good one to ask about making your own.:thumbup:Later,
Kelly
03-03-2002 | 05:45 PM
#5
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From: Oxford, MS
JMP air trap
ishu4u,
I have been using a BVM UAT's since they came out. I have several hundred flights with them and have had very good sucess with them. Like NO FLAMEOUTS..... On my Bobcat last fall I ran the UAT down to the point it had less than 1 oz of fuel in it (4oz tank) and the engine was still runnning. I believe as liing as the bag is wet it will work. I am a believer and will not have a turbine plane without a UAT in it.
David Reid
I have been using a BVM UAT's since they came out. I have several hundred flights with them and have had very good sucess with them. Like NO FLAMEOUTS..... On my Bobcat last fall I ran the UAT down to the point it had less than 1 oz of fuel in it (4oz tank) and the engine was still runnning. I believe as liing as the bag is wet it will work. I am a believer and will not have a turbine plane without a UAT in it.
David Reid
03-03-2002 | 06:26 PM
#6
My Feedback: (6)
JMP air trap
As Kelly said, if $$$ is a problem (and it is now for me as I had to buy a new car yesterday... JEEEZZ!), go here: http://www.jetpilots.org/how_to_buil..._pleated_p.htm I've been doing it this way now for two years and NEVER an unexplained flame out. Works great. I put it in a 20 or 24 oz. Dubro tank with BVM aluminum caps.
03-03-2002 | 08:50 PM
#7
My Feedback: (2)
JMP Air Accumulator Tank
To answer Vincent's original question, this tank is positioned downstream of the main fuel tanks and upstream from the fuel pump.
There are three features that differentiate this tank from others, (1) it is made of metal so its more robust and may survive a crash better, (2) it has an internal fuel filter element [other than its membrane sack] that eliminates the need for a secondary filter elsewhere in the fuel circuit, reducing the number of fittings, (3) it has mounting features that allow you to screw it down with no additional hardware.
I don't have one yet so I can't give any reliability data, but I look forward to trying one out some day.
Kelly
PS: I am not a sales rep for JMP, just TJT only... I currently have BVM tank in my hotspot, still under construction.
There are three features that differentiate this tank from others, (1) it is made of metal so its more robust and may survive a crash better, (2) it has an internal fuel filter element [other than its membrane sack] that eliminates the need for a secondary filter elsewhere in the fuel circuit, reducing the number of fittings, (3) it has mounting features that allow you to screw it down with no additional hardware.
I don't have one yet so I can't give any reliability data, but I look forward to trying one out some day.
Kelly
PS: I am not a sales rep for JMP, just TJT only... I currently have BVM tank in my hotspot, still under construction.
03-03-2002 | 08:55 PM
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From: Rochester,
NY
JMP air trap
Originally posted by woketman
As Kelly said, if $$$ is a problem (and it is now for me as I had to buy a new car yesterday... JEEEZZ!), go here: http://www.jetpilots.org/how_to_buil..._pleated_p.htm I've been doing it this way now for two years and NEVER an unexplained flame out. Works great. I put it in a 20 or 24 oz. Dubro tank with BVM aluminum caps.
As Kelly said, if $$$ is a problem (and it is now for me as I had to buy a new car yesterday... JEEEZZ!), go here: http://www.jetpilots.org/how_to_buil..._pleated_p.htm I've been doing it this way now for two years and NEVER an unexplained flame out. Works great. I put it in a 20 or 24 oz. Dubro tank with BVM aluminum caps.
03-03-2002 | 10:02 PM
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From: Oxford, MS
JMP air trap
I was not knocking the JMP product by any means just stating that the membrane type airtraps like the JMP and the BVM are very effective in eliminating the air bubbles getting to the engine. I have no experience with the JMP air trap but do with.... the "Other Brand"
Does that make you feel better now?
Does that make you feel better now?
03-03-2002 | 11:05 PM
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From: Mill Creek, IN
JMP air trap
Has anyone tried using one of these devices on a ducted fan setup. or do they only work on turbine installations? By that, I mean are the fuels properties different enough to render one useless for regular glow fuel.
03-04-2002 | 12:59 AM
#12
My Feedback: (2)
David R
Sorry David, didn't mean to put words in anyone's mouth by "slamming" one product or another. Not my intension at all...
The fact is the JMP unit is kinda' new and nobody seems to know much about it. Just wanted to shed some light from what I heard. As I said, I have absolutely nothing to gain by promoting a tank over BVM's or anyone else's. The fact that I have 2 BVM tanks and I am very happy with them both should be enough proof.
If I'm a little long winded its because I'm an engineer, unfortunately we all like everything into 50 decimal places...
Later,
Kelly
The fact is the JMP unit is kinda' new and nobody seems to know much about it. Just wanted to shed some light from what I heard. As I said, I have absolutely nothing to gain by promoting a tank over BVM's or anyone else's. The fact that I have 2 BVM tanks and I am very happy with them both should be enough proof.
If I'm a little long winded its because I'm an engineer, unfortunately we all like everything into 50 decimal places...
Later,
Kelly
03-04-2002 | 01:42 AM
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From: Oxford, MS
JMP air trap
Kelly,
My post was not directed at you in any way. The person who it WAS directed at did not understand that I was not promoting one product over another just merely pointing out that the concept of eliminating the air bubbles with this type of unit is an excellent idea. Some people just take things the wrong way.
My post was not directed at you in any way. The person who it WAS directed at did not understand that I was not promoting one product over another just merely pointing out that the concept of eliminating the air bubbles with this type of unit is an excellent idea. Some people just take things the wrong way.
03-04-2002 | 05:54 PM
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From: Olathe, KS
JMP air trap
Vin- THe JMP air trap is engineered for the turbine crowd. It goes after the header tank or tanks just ahead of the fuel pump. The difference between the JMP version and the BV UAT is the JMP unit is made of alum. to maintain integrity in the event of a mishap and it has an a replacable filter inside the membrane to collect any stay fibers.
I've seen this unit in operation and it will not let any air into the fuel till only about 90% of the volume is air. Amazing.
One will be on my next tubine.
Hope this helps.
Marty O
I've seen this unit in operation and it will not let any air into the fuel till only about 90% of the volume is air. Amazing.
One will be on my next tubine.
Hope this helps.
Marty O
03-05-2002 | 01:17 PM
#15
JMP air trap
Thanks Marty for the info. There are two models, one for vertical and the other laying flat. Tom Cook says its unlike any other air trap / header on the market at this time. Its kind of creepy though not to be able to see inside like the plastic tanks.
Vin...
Vin...
03-05-2002 | 06:01 PM
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From: Olathe, KS
JMP air trap
Vin- If you ever saw Tom's demo unit with the clear plastic housing that is made the same as the metal unit, you would forget about ever wondering how good it works.
You aren't able to see into your wing tanks or hopper tank if they are molded and they work.
Tom and JMP test their stuff extensively before they release it for market, unlike some other manufacturers who use us modelers hard earned money to work out the bugs instead of a comprehensive test program
Bolt it on and forget it.
Later
Marty O
You aren't able to see into your wing tanks or hopper tank if they are molded and they work.
Tom and JMP test their stuff extensively before they release it for market, unlike some other manufacturers who use us modelers hard earned money to work out the bugs instead of a comprehensive test program
Bolt it on and forget it.
Later
Marty O
03-05-2002 | 06:37 PM
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From: Ft Wayne, IN
JMP air trap
What is the fuel capacity on this baby?.
I have JMP Electronic Gear Door Sequencer, and the JMP Gear/Door Airline Manifold in my SJ F-16, and they work great!!
I have JMP Electronic Gear Door Sequencer, and the JMP Gear/Door Airline Manifold in my SJ F-16, and they work great!!
03-10-2002 | 04:11 AM
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From: Overland pARK,
KS
JMP air trap
I live near Tom and was one of the first to use the tank. I have it in my Hotspot(P-80) on the horizontal. I bought it after I saw the plastic prototype work. Tom has the bag in it with an inner filter as well. I could not believe my eyes when he showed me the plastic prototype when it was 1/4 full and I shook it, turned it all over with a turbine running on his test stand. No bubbles!
Since then, I use it with complete confidence. Tom should put this demo on his website and then you'll be convinced. I wouldn't have believed it unless I saw it.
I also like the metal can for safety reasons. Why buy kevlar tanks and then use plastic for the header? That was my rationale...
Dave
Since then, I use it with complete confidence. Tom should put this demo on his website and then you'll be convinced. I wouldn't have believed it unless I saw it.
I also like the metal can for safety reasons. Why buy kevlar tanks and then use plastic for the header? That was my rationale...
Dave
