I am currently setting up a new sport jet and I am trying to decide where to position the UAT. Does it matter whether the UAT is tilted forward or tilted aft? The most advantageous position would have it tilted toward the aft end.

I have always installed them tilted forward but I can't honestly say why.

I have installed it facing forward, rearward, flat(not on it's side), and tilted up. Any of those combo's are sufficient.

This all probably stems from Uncle Bob's suggested installation of his UAT that is included in his UAT. To summarize, it pretty much says, facing forward and tilted up.

I have a UAT in my bandit that faces aft and is tilted up.

The nipple to the main tank must be highest .So when you fill to remove all air from UAT.
my2c

OK. Thanks. Mounting it facing aft.

I have done it front, back and sideways too, never a problem. I do stick with the BV high flow UAT though. I'm not sure it matters as long as its like stated above, I always tilt it and make the fiIl nipple the highest point of the UAT when filling. That will push the air out of the UAT, thru the tanks, and out the vent.

If the fuel system works as it should and ( like said) the feed nipple from the main tank is highest during filling, it makes almost no difference. I’m sure Uncle Bob showed the UAT vertical in the composite BC, since that’s how it is in mine.
All my Xcalibur models have the facing rear and using the MAP traps they are mounted horizontal as the pleated filter is not as fussy as the fan tail bag.

If you fly more acrobatics and downward lines you'll get more air in the trap than people who simply fly a flat pattern around the field. With it in the upward angle position it's less likely to get air to the turbine. I don't recommend it laying flat or on its side in my experience but I do fly more acrobatics and downlines

I have one of the basic rectangular UATs (Hanson, but same same) on its side but also tilted up due to space limitations in a JHH A-7, no issues to date with it that way. The nipple that goes to/from the main tank is still the highest of the 3.

If you fit a felt clunk you don't get air!

I have no air after a flight with lots of vertical. Only BVM bag type UAT's don't like being horizontal, everything else does not care.

Its very interesting this debate, especially as most of my 'modelling' focus and products have almost exclusively been around fuel delivery and air management.

Most UAT's can be mounted in any orientation, its good to have a UAT that can be emptied of air by a reverse pump action, however following a lot of research and testing my view is to focus the biggest effort at the 'source' i.e. in the tank where the air is first ingested.

On a precautionary note there are many materials used to 'separate' or 'prevent' air from entering the pump side of a fuel system, most are not designed nor intended to be used with fluids, in fact most are for pneumatic applications not fuel systems.

I'm happy to fully refund in full anyone who can prove my BULLET clunk products don't reduce dramatically the amount of air drawn into the UAT or pump regardless of your flying style

This might be of interest to those who perform aerobatics:

Natrix and Bullet - the basic facts were like following: after starting training for f3s schedule/maneuvres we faced Hoppertank about 2/3 empty after each flight as shown on the pic - no shutdown of turbine but not acceptable and dangerous - schedule/aresti attached. That never happend before performing showflights or flying just for fun, so it must have been caused by all the long downlines in the given schedule, placing kero in front of the tank and having clunk outside of fuel... and Turbine cutoff is nothing you'll face during competition...
Replacing Brassclunk by Bullet solves that issue immediately, we never experienced any airbubbles in the Cat again, not one single ml of air. We tested 220N Behotec at full throttle - 8mm Bullet buffers 8 seconds "airless" runtime after being moved out of kero level on testbench.

This is from Patrick Hofmaier who won the German F3S championships this year flying a Paritec Natrix.

marcs

I just got a bullet, ordered from DW, and was excited to try it out in my new build I'm doing....didnt fit through opening in my Jet Tech tank.... needs to be a longer slimmer version for these cases....

The Bullet was designed to fit through the Dubro metal ring fittings, unfortunately in the USA some fittings are not worked around metric dimensions, the design has been optimised for surface area.

marcs

Are you guys filling your tanks through the UAT or directly to main tank?

I always fill through the UAT - never actually seen an installation not done that way, but maybe I haven't paid enough attention either.

That is what I thought. I have the fill line at the highest so I can suck the air out.

Perfect.

marcs

Make it longer and narrower which will give it equal surface area.

What's a bullet?

this is what he is referring to,,
Dreamworks Model Products LLC

Thank you.....

Dang, out of stock at Dreamworks. Any idea when they will have more or are there other suppliers on this side of the pond?

Hi, just PM me and I can send from UK, post wont be much as the item is small and it will be done at cost.

marcs

Send me a pm and I'll sell you mine I just got from dreamworks...

Thats a plan too...

marcs

Thanks guys. PM sent.