So my question is this, is a UAT really that much better than using a plain header tank? I know the purpose of a UAT is to eliminate air bubbles in the fuel tank, but I don't see how air bubbles could form in a header tank that is full of fuel the entire flight. Also turbines have very low vibration so that would also make it harder for air bubbles to form as opposed to a gas engine. Basically would just like to here some opinions.

I have never heard of anyone not using some sort of UAT in their planes. Some make there own and have had success with them. I would be interested in hearing form people that use nothing but a header tank too.

That being said, I have used a UAT in every plane I have owned and have never had a flame out due to a bubble.

U.A.T. all the way!!! I tried once without one, had flameouts galore, installed the UAT and changed nothing else, never another flame out... Russ

Yes, use a UAT. It's cheap compared to loss of your Jet due too a flsameout.

James Love

I have never heard of anyone NOT using a UAT or hopper tank. I certainly wouldn't!

The fuel gets sloshed around pretty good during flight with the type of flying we like to do. So it is not unusual for a bubble or two making their way through to the UAT during flight. I saw one fellow forget to refuel after a flight and went up for a second flight. He shut down after taxiing back to the pits and both the tank and UAT were bone dry! He must have used all but a couple of molecules of fuel during that second flight....! But the turbine kept running on bubbleless fuel til he shut it down. That was as convincing a demonstration as you could ask for of the value of a UAT !

I have over 1000 flights on three Roo's with no UAT's. I have used pop bottles, juice bottles and now I use one DUBRO 50 oz center, 2 DUBRO 24 oz on either side on the main tank. On top of the main tank, I have a 6 oz tank with normal heavy clunk. I always land with the header full, and never have bubbles in the header. I have never had a flame out in all these flights. The turbines are two AMT USA Mercury's that just run and run.
Ron

You don't need a UAT, unless you have the money but not the time to build a header. Try [link=http://www.jetpilots.org/how_to_build_a_turbine_pleated_p.htm]THIS.[/link] Works perfectly and is WAY cheaper!

I remember when the U.A.T was first introduced. There were loads of people who said things like " I`m not paying £50 for a plastic bottle" and the like. I have some really really tight modeling friends ( who don't read this forum) and they also said they would never buy a U.A.T but even they have now got one after they were the only one down our field who were getting flame outs regularly. I suppose you could try and make one out of a empty washing up liquid bottle, a toilet roll tube, sticky tape and a cornflake packet but personally I would rather spend the money and get a U.A.T.

take it easy
Jason

I never used a UAT... I always used a header tank without a clunk, but with the fuel pickup at
the center of the tank and never had a problem related to this system in years, neither all my friends here that use this same method.


Best regards, Enrique

I'm trying to guess who you mean...............

Just to be sure, all of you who had bad luck without a UAT did you use a header tank?? or just the main tanks, because my point was a "header tank" as opposed to a UAT, not without either. As I just can't see a header tank that is full all of the time causing air bubbles.[sm=confused.gif]

my story is that I have the FTE 500 and have about 20 runs on it, two being flights and I have not had any problems with fuel delivery and my setup is a regular 60 oz tank running to a 10 oz header tank, my flights have been from a fairly rough grass field and I have also done taxi test on the grass field bouncing the heck out of the plane, all without the engine quitting. So I guess I'm trying to see from other experience if I'm playing Russian Rullet or not. Seems to be fairly split but I would like to know if the people with the bad luck were just running off of a main tank or also used a normal header tank?

question is........ how much money do you have invested into your jet? the UAT's are proven to eliminate air bubbles. is it worth loosing a jet by trying to cheat on the fuel system?

just my 2 cents

'
mark

Not trying to be cheap, I'm just looking at the view point of fads vs physics.... I want definate facts/science behind something I'm purchasing. I know $50 is cheap insurance on a $4K + investment but so do the people making a selling the products.

And is this hobby there are a ton of Fads, ie the popularity of the F18 and Yak. Heck a two years ago nobody was flying a Yak, now to be able to compete in 3D seems like you need a yak, and a lot has to do with perception over actual fact.

Well, good points by everyone. I fly helicopters, and not upside down a point that can make a huge difference. I have only used a 2 oz header tank, set so that the pickup is on the bottom, the fuel comes in at the top, my pickup in the main tank is felt covered. Never had a flame out, nor bubbles in the header after flight. Helicopters naturally make the fuel foam once air is in the top of the tanks.

For what that is worth.
Jack

Jason and Mark: you guys must try looking at this from my view point. In the years that I have used a Dubro tank and the pleated paper filter I have NEVER (not even once) had even the slightest issue or flame out due to them. Yet in those same years I have seen two issues and/or flame-outs caused by properly installed UATs.

Therefore I can only conclude that A) the pleated filter/Dobro tank works BETTER than the UAT (in my direct experience), and B) it costs far less than the UAT.

So from my point of view I would ONLY choose the pleated filter since it is more reliable (in my direct experience) to protect my investment.

Now, I will concede that UATs do seem to be reliable enough (just not as much so as my home made header), so if I did not have the small amount of time that it takes to make my own, I might purchase a UAT. But that is not the case.

I cant see how a properly installed UAT can cause problems can you tell me?

As for the header tank idea, yes they do work but if for what ever reason it gets half full of air you have a flame out, but with the uat you can almost empty it.

jason

If you use a header tank,(as I do),don't use anything bigger than 4-6 oz's.
The bigger the tank the more fuel sloshing and chance of picking up air.
The paper filters will deliver solid fuel with only part of them in the fuel, something about surface tension.

I find it a little hard to believe that these 2 were properly installed and bled of all air.

The pleated filter hopper is definitely easier to install as there is no internal element that can possibly hold air if not bled right.

Jason, one of the issues was at Mississippi Afterburner circa 2001 (I think, could be a year off). It was in Dennis Lott's BVM F-4 (awesome aircraft!). Dennis would have to address this to be certain, but from the way I understood it it appeared that the UAT started leaking around one of the fittings. It was one of the planes first flights (I think) and it ended in a dead stick that was a close call. The other failure was at that same jet meet, but to tell you the truth I don't remember any details about that one so lets just wipe that one out (all I remember was that there was another problem, possibly related to the same failure mose).

You said "but with the uat you can almost empty it". ANOTHER reason to use the pleated paper instead! With he pleated paper, you CAN empty it! I once flew the original Isobar dry just to test the pleated paper technique when it was new to me (I guess around 2000 - 2001). I dead sticked her in and looked at both the main tank and the header tank. The main had a tiny bit of residue in it that could be seen only if you tilted the plane so that anything left would gather in one corner. Same thing for the header with [erhaps 2 or 3 drops remaining. I was truly amazed. The surface tension phenomenon (the same reason that a UAT does its job) keeps the pleated paper pick-up sucking fuel even when 95% of its surface area is exposed to air (that's what Steve Ellzey told me they had shown in the Lockheed Martin lab in Texas where he works on small turbine powered cruise missiles back in the 2000 time frame, which is why I tried the pleated paper).

Gary, the way I uderstood it they were indeed properly installed and bled. They simply had a failure to seal at or near a fitting. Dennis needs to say exactly what happened.

I'm with Woketman, pleated paper filters are the way to go. My main tank has a pleated paper clunk made from a Fram CG3388 filter as shown in the link Woketman provided. Additionally I made a header/UAT by rigidly mounting a Fram CG3389 filter in a Sullivan 4 oz. round tank mounted upright. It's similar to the last photo in the thread referenced below. The CG3389 is the same as the CG3388 except it is 2" long instead of 1".

With this system I can run my turbine until the tank is bone dry. It's been totally reliable for 81 flights so far. Here's the thread from a couple years ago that convinced me to go this way.
http://www.rcuniverse.com/forum/m_20...Cfilter/tm.htm

Some of you would rather send Uncle Bob $60, and that's fine if it makes you feel more comfortable.

Joe

I have UATs for my RAM500 FACET and Cougar. Both have flamed out at one time or another due to retained air in the UAT despite conscientious effort to be sure all air is excluded from the UAT before flight (eg inverting, tapping, shaking with turbine running-not always an easy procedure). It is a pain to try to get all the air out of a UAT, particularly as I frequently open the fuel system and shift the turbine between the two aircraft. The UAT is also a pain because it is best mounted upright and is only available in one size with only one size tubing connectors (5 mm polyurethane). It does serve as an additional 'final filter'

I am using the felt clunk supplied by JHH and Wren with my MW44-Sabre. Seems to work well permitting almost all fuel to be emptied before bubbles. However, the (Tygon) fuel tubing I use stiffens up in kero over time, and does not let the Felt clunk move around inside the tank as well as I would like. I know BVM used to have a thinner walled more flexible tank clunk tubing. Does anyone know its specs and where one could get a yard or so?

With the thousands of money invested in a turbine project a $60 UAT is not the place to try to save some $'s. $60 may seem like a lot of money for a 4 ounce header tank but the work....all the time!! If properly purged on a new installation they will never give you any trouble.

Ron

Yeah but the point is why spending 60$ on a plastic tank with a anti-bubble socks when you can make a probably better and a lot more user friendly one(pleated paper filters ) for 5$ ???

Glorfindel has it right. In my experience the pleated paper works better than the UAT plus you can choose the size tank (I use it for extra capacity at the end of a flight. I know that if near the end of the flight my main tank might be bone dry so I still may have 20 or 24 oz left in the header. As long as I don't go wild on the aerobatics - which I would not cause I'm just trying to land at that point - I have that header reserve) plus I don't have to undergo any complicated hijynx to purge it (just tilt the airframe a bitwhile fueling to allow every single bubble out) plus it don't cost me $60!

Don't get me wrong, BVM stuff is for the most part the best stuff out there! But for a few bucks I can put something in my plane that, in my experience, is more reliable AND more user friendly.