Shaun Evans

Hey Guys,

I have an installation I'm doing on a Y/A F-16. This is the now out-of-production ARF version that has a very nice cockpit. The problem is that since I'm installing the cockpit, the regular-sized UAT will not fit anywhere in the plane with the Jet-Tech tanks installed. I've got a little header tank built from a 2-ounce DuBro tank (the hard plastic) with the pickup being a 3/16" brass tube that terminates in the center of the tank. No bag, no felt, just suspended where there shouldn't be any bubbles unless the main tanks run dry. Would you use it?

I know some guys won't fly without a genuine UAT, and other guys have thousands of trouble-free flights without ever having used one. What do you think?

Square Nozzle

My Feedback: (1)

Shaun, there is a mini UAT (2 oz) available that will replace your existing 2 oz header. Look at Dreamworks and do a search for "UAT".

CraigG

My Feedback: (40)

I would definately check the 2 oz tank for bubbles/air after the first few flights but if the rest of your fuel system is tight, I think you will be just fine (and better than having no UAT at all).

Craig

ViperOneNL

Hi, I would say it depends on the total fuel setup.

1) 1 fuel tank and the clunck reaches all corners no uat needed
2) 2 parallel fuel tanks UAT mandatory
3) 2 fuel tanks in line, and cluck can reach all corners in the first tank seen from the pump no UAT needed.

Btw I always use a uat (and some times 2 in line) most of the time overkill but better save than sorry IF you have the space.

My 2 cents

Mick.

marc s

One of these should help, bubble trap and can be stood on end - Todd (Dreamworks) sells them

PM me if you need some advice on them.

marcs

John H.

Use a felt clunk works great.

John

Henke Torphammar

I do that in my Kolibri powerd planes(funjet ultra and Baiojet), it does work well as those planes always flies with G-load.However on a slowflyer jet you will see zero G manovers where the clunk is at the back of the tank and the fuel in front and a flame out might occur.

Jame

I would also go with the GBR Jet CAT, had the same problem in our Flash, the install we wanted, didnt allow the use of a standard BVM UAT so we used one of Marc's Composite Air Traps, nothing wrong with any of the UAT's weve used before but you cant beat the quality, weight and cosmetics of the CAT's.

Kind Regards

Jame

Henke Torphammar

I got the 750cc version of Marc's tank and it is very good quality! [sm=thumbs_up.gif]

Shaun Evans

Hi,

Where are you guys getting the pleated paper filters from?

Xairflyer

My Feedback: (1)

No problem with a centre pickup tank works well, I dont believe UAT's are necessary with modern turbines, they were a fix for fuel problems in the past, modern turbines can cope much better with the odd air bubble.

Jgwright

Sean

I bought my last lot off US Ebay. They are not quite as common now as they used to be as the cars they were for are vintage!

http://www.youtube.com/watch?v=QUv7j...4&feature=plcp

If you have a look at this video this plane has 2 tanks one drawing though the other and no UAT. The video ends before the plane runs out of fuel but you will get the idea that the pleated paper filter pickup will work until the tank is nearly empty. We have flown this glider till the tanks were empty several times and the engine does not stop however extreme the manoeuvres. Plenty of negative G manoeuvres, 10 G positive and -6 G negative.

I am about to make some pick ups for myself if you PM me I can make an extra one up for you.

John

BaldEagel

You can get them at "In line filters" in the UK, do a google search.

Mike

Gary Arthur

My Feedback: (29)

I have a L39 Wren 44 powered. It has two tanks in series and a small 2 oz header just as you described. I usually land with one tank half full and never have bubbles in the header providing there is no leaks etc.

tobba

CAT's are brilliant - I'm running 4. Best quality, robust, simple and compact.

Wayne22

My Feedback: (2)

..just be aware that there is a documented situation with some felt clunks can cause restriction in the fuel line and will actually cause the fuel to cavitate and form bubbles - exactly what you do not want to happen. I've had this happen to me, and have seen it happen to other people, consequently I never ever use felt clunks... YMMV...

marc s

Maybe but most still don't like bubbles, as far as I know Hawke Turbines are about the only bubble tolerant turbine in the market and that's due to the combustion system being totally different to almost all other turbines.

A UAT provides other functions as well, if you have a faulty fuel system with an air leak the UAT will show evidence of this, a tank may not and is often not visible at a quick glance. A UAT is also a fuel reserve, just about every fuel propelled vehicle and aircraft has one so why not an RC jet, and that extra fuel gives you a margin to play with too should you get delayed in your landing plans.

marcs

FenderBean

Hey shawn what fittings are those on your main tanks? looks like your clunk line has the ability screw in. and whats the inner diameter of your vents you installed?
im considering making my own for my next projects since I need 4 and that adds up, plus i just like to build things.

FILE IFR

Those have been around a while.. Todd has them for the custom tank builder type guys.

Xairflyer

My Feedback: (1)

I agree Marc with the header/reserve idea, my point was you don't need the superdoper £60 UAT a standard fuel tank with a centre pickup (as shown in the Jetcat manual) is all that is needed.

marc s

Just to clarify mine are not £60 for the 'standard size' type unit, and more importantly many simple plastic bottles collapse under suction - which as I am sure you know is not the best condition to subject your fuel pump to when trying to deliver a constant fuel supply to a turbine.

I'm thinking by the time you have faffed around buying the container, adding the pipe/fittings and making sure it does not leak, then mounting it surely £30 something odd is not exactly a kings ransom..... oh and I forgot the cost of your time too.

marcs

kevinthoele

My Feedback: (1)

Shaun

My Avonds F16 flew 742 flights with 2oz header tank with no issues before a midair ended its career.

Xairflyer

My Feedback: (1)

Although I was not referring to yours, actually Marc your CAT's do look the £60 in the way that they are made, where as the well know one I was referring to, should be half that.

UAT's dont need to be made as a copy of the purple one's chemical bottle, any standard fuel tank can be used so long as you say it is rigid enough. I have used the 4&6 oz Dubro ones plus have just sourced some nice square solid ones that would also be ideal.

schroedm

My Feedback: (1)

Stick with a CAT. Much cheaper than the 'famous' one, doesn't collapse, works perfectly and is only a couple of quid more than faffing around making your own that won't look anywhere near as nice

Gordon W

Thanks Mike. Whilst I already have a few Fram 3388 and 3389 filters, both in use and on the shelf, that I bought cheaply from overseas a couple of years ago, it's good to know of a UK supplier. Faffing about making things and maybe even saving a few quid is one of the parts of aeromodelling I've been enjoying for 50 years.

Gordon