PST and AMT engine performance.
 

The newest two gas turbines on the market are the PST J600 and the AMT Pegasus HP.

I am delighted to report that I flew both engines at our big Australian jet meeting this weekend with first class results.

The PST J600 completed 12 flights in my BobCat and performed absolutely perfectly on each and every flight. This combination is just superb, the engine a pure delight. There were another 7 600s at Mangalore all performing faultlessly. (The take off flameouts on my 600 powered BVM Sabre were caused by an airframe fuel system problem, probably incorrect initial set up of the new UAT ).

I also flew the AMT NL Pegasus HP in my BVM F4 and the performance is amazing and the sound perfect. Engine, and airframe, operation were perfect and again this is a superb combination.

( I am a rep. for neither company and since I paid for these and all my other engines I am merely a very happy and satisfied customer).

BRG, David Gladwin

PST and AMT engine performance.
 

David, I had similar flame-out problems with my 500 powered Sabre until I remounted the UAt so that the cap end was about 20-30 degrees tilted up. I also installed a JetCat fuel filter in the line between the pump and engine. If you haven't already, you might try this.

UAT
 

Tony,

I just installed a UAT in a new project and mounted it vertical?? I believe that is ok?? any coments??

Thanks,

Vin...

PS: are you coming to the AJR??

PST and AMT engine performance.
 

I have the UAT mounted cap up, vertical in my jet, and not one flame out in 20 flights.

PST and AMT engine performance.
 

FWIW,

I find you have to be very careful to ensure all the air is expended from the UAT the first time you use one. Once this is done they seem to be very reliable. I think I am right in saying that the latest versions of the UAT instructions are very specific on this matter.

PST and AMT engine performance.
 

It seems that the best orientation for the UAT is that the cap is facing BACKWARD and up at an angle of 20-30 degrees. It seems that, from my limited experience of three UAT's, that this way it fills almost completely . This is ASSUMING you followed the bvm directions re: purging!!!

Hey David, can you comment on the fuel and power measurements of these two engines?

PST 600
 

Just got my second PST for my BVM F-86. Shot a few pictures of the engine.......

#1

PST 600
 

Photo 2 shows a feature I really like... The EGT probe has mounting brackets and is not just held in place by the mounting straps. Very nice..

PST 600
 

Photo #3 shows the GSU. A four line display gives you all kinds of read out. Visible in direct sunlight.

During start-up the entire sequence is shown (glow on, gas on, kero on etc.)

RPM, EGT temp, battery voltage Fuel pump voltage is shown all the time. Other menus allows for RPM settings, glow settings, RC set-up etc.

PST 600
 

Photo #4

The solenoid has a neat feature. It has a small red LED that lights up when active. The solenoid is tiny and lightweight.

The onboard gas tank is the same size as the one supplied with JetCat. The tubing between the solenoid has a restrictor built in to ensure correct gas pressure.

Starts equally well on Powermax or regular propane.

Test stand
 

Just test ran engine number 2 on the stand. Got 12 3/4 lbs of thrust @ 160K RPM. Temperature is 85 degrees here today

PST and AMT engine performance.
 

Thanks guys. Just checked latest BVM instructions on new UAT supplied with my F16 conversion kit and yes there is an addendum about purging via the feed pipe. Will try that.

The perforrmance of the PST was published in the last edition of RCJI and the AMT thrust and performance will be tested as soon as the autostart software has arrived. However the burn in the F4 was just a little higher than the original Peg as I could operate at lower revs for the same performance, but it was tempting to use all the thrust available at times !

With standard tanks in my BobCat with the PST I fly for 5 minutes and there remains about 40 % fuel on landing. UAT works perfectly in that aircraft but it is mounted facing aft and inclined upwards at about 45 degrees !

BRG,
David Gladwin

New Engines
 

I saw the new AMT NL Peggy HP installed in Jonathan Smith's Super B at FIJR. It is a beautiful piece of machinery. According to Jonathan, who spends time with Bennie while Captain of a TNT Airbus that routes into the Netherlands, this Peggy will put out 40lbs, but will be sold as a 35lb unit.
No question that the high thrust end of engine development is moving right along. It will be interesting to see what JetCat will be doing with the P-200 development and AMT with the 400 to meet the competition.

On the low thrust end, that PST is a beauty. Proper development of the MW54 basic concept---Jason Fletcher's standard MW-54 Maverick performance was spectacular at FIJR. The PST, with the fine autostart, is going to give SWB some real competition if they don't make a real effort to get some Mamba's out flying.

RE: UAT, etc.

I have had but one flameout in my P-120 HotSpot with 120 flights and P-120 Bandit with 25 flights. That occurred at FIJR on the recovery downline after a 5 turn inverted flat spin following a outside flick entry. Who really knows what happened, but I am convinced that air-bubbles are still a gremlin.

I have taken a UAT apart, and the fine mesh bag does have allot of crevices that can trap air if it is not properly removed initially. We like to hold the plane up, oriented so the UAT outlet is skyward at 90, and then run the engine up to full throttle, followed by as vigorous a shake you can give the model (Use ear protection!!). We do this every so often, not just initially. Air can get in thru cavitation, i.e. sealing of the input and output lines with a temp change, or trying to pump fuel out of the UAT with the intake line restricted, most often due to forgetting to remove a vent line plug. It's usually not a true lack of fuel, but the air that cavitates into the line that kills the motor.

Not only can UAT's be culprits, but our high volume filters (big plenums) can also trap air. Now Bob and the JetCat guys are suggesting to also orient the filter as close to vertical as possible.

So, I have had very good success with trying to keep the UAT and filters as close to vertical as possible(often problematic due to size and footprint constraints), and flicking the filter and doing the full throttle run-up with the UAT near vertical fairly often.

Tom

PST and AMT engine performance.
 

Interesting point on the UAT. Question is, if it can trap air and needs to be shaken and stirred , why use it at all ? I have over 100 flights on my AMT F4 and Jetcat F15 using simple 4 ounce hoppers with geometrically centered pick up and not one flame out. Cost was about £2 or $3 with perfect results on high end models. Filters are fitted and are horizontally orientated. If BV and JetCat are saying the filters must be orientated vertically then that must be a correction or compensation for some other fuel system problem. On the F4 I can't even see the hopper or filter , but I get perfect engine runs every time, isnt there something about keeping it simple , make it work. (Boeing philisophy)

On the PST/SWB topic my personal guess, as the owner of two 600s, is that the PST is now leading the field as the standard to equal. It is beautifully made, works perfectly, and autostarts first time every time without an air bottle. And it is available now at a very reasonable price. How can that be bettered ?

BRG,

David Gladwin.

Nobody's rep !

PST and AMT engine performance.
 

David,

Since switching to using the UAT none of us in our group of flyers has had a fuel related flameout after several hundred flights. My UAT is mounted horizontally with the front of it tilted upward at a 15 to 20 degree angle. After landing I have noticed only a few small bubbles in the UAT which is normal if you fly any aerobatics at all. I believe that the key is to NEVER let your fuel get down low enough to start to consume the fuel in the UAT. NEVER defuel the UAT. I have not ever had to thump or shake the UAT to disperse a bubble 'cause there hasn't been a large enough bubble to cause a problem. When fueling, the small bubble (that was there from the previous flight) gets expelled. If you notice that there is a much larger bubble in the UAT than usual it is time to start troubleshooting the problem as you are getting air in the system from somewhere.

Kevin

Filters
 

David, your points about air-traps are well taken. Long before the UAT appeared, we all flew our D/F, with those skinny little saddle tanks that were prone to unporting, for years with a 1 or 2 oz sullivan or Du-Bro hopper tanks--and allot of guys worldwide are flying jets without UAT. BV has added baffles in the BobCat wing tanks to prevent unporting, as you well know.

The UAT, at least in my experience, does not let an air bubble of flame-out size to cross the membrane from the feeder tank(s). That's the beauty of the thing. I have tried by blowing into the UAT inlet port while running my fueling pump on the output side. And it maintains this property until it's almost empty.

I was just letting people know that any air that can get into the output side of the UAT through cavitation, or backfilling air into the sack while doing any sort of maintainence on the output side tubing, can get trapped, only to appear at a later date. This is different from the 2 oz hoppers since you could see the bubbles in the hopper, but they are not visible in the UAT sac or in a solid metal case filter. Worth checking once in a while. Sort of like sumping the tanks on my full scale. In 40 years of flying, I only found water of significance once---but that probably saved a bent plane and body.

I also have had hundreds of flights with my filters oriented horizontally with no problems, but once again, that air in the output could get trapped. How often does this happen? Probably infrequently.

However, if you orient the UAT and filters more vertical than horizontal, so the bubbles rise to the top, then they should appear at the engine long before takeoff and not just after lift off.

The only reason I think this thread has any value is because at all the meets I have attended this year, flameouts are still occuring---this in the face of the new engines and ecu software which makes them very resistant to flameout---except for the wayward bubble train or solid contaminant like algae.

Tom

PST600
 

I am very interested in the PST600. I have not researched where to get one and how much. Can you guys shed some light? are they in stock? Are they as noisy as the ram500? any info is appreciated!!

BTW, I have also used the regular 2 oz hopper tank with a felt clunk and to date, 100 flts on a roo (sold the roo), no problems!!

PST and AMT engine performance.
 

Hi Guys,

So if the flameouts are still occuring (and one or two may even be attributable to the UAT), is it the case that we've been hyped into buying the world's most expensive Nalgene bottle?

I've got a UAT in my Reaper and had a flameout while taxing just after fitting it. I had shaken the UAT thoroughly and pumped quite a bit of fuel through it to try and flush all air out.

It hasn't happened since, so I guess it is now air-free and working as expected.

What do people think?

Regards,
Garrett

PST and AMT engine performance.
 

Hi Everyone,

I recently flew at the FIJR(great meeting you Tom and Jane BTW). Before I shipped the model I drained all the tanks including the UAT. Now the interesting point is, before I flew the first flight at Lake Wales I had the jetcat flameout three times when I shook the model. In all cases I am convinced it was air in the Filter and not in the UAt as the flameout was instantaneous. The UAT is about 16 inches from the turbine so if it was air in the UAT then it would have taken a few secs. However, the filter is about 3 inches from the turbine. In addition, the filter is orientated horizontally and not vertically.

FWIW I think the UAT is not the panacea to reliable turbine operations. As Dvae says, there are plenty of guys operating turbines with plain header tanks and they don't have any problems. I think it is just an aide to increase reliablilty but it won't fix a bad installation.

On the other hand I also think that using some sort of felt clunk also helps dramatically but I know some people have issues with these. In fact , I was told in no uncertan terms not to use them. Anyone get any opinions on this?

Geoff.

PST and AMT engine performance.
 

So far I have 33 flights on my MW54 powered SR and am using a simple clunk made from an automotive fuel filter. It works like a felt clunk but without the risk of felt bits clogging the filter. I have never suffered a flameout with this simple system. I was going to fit a header tank but found this to be reliable. I was concerned that on extended downlines , when the clunk is exposed ,I would have problems. The Orbit membrane clunk is very nice but was too big to fit in my Dubro tank.

Mick Reeves is an advocate of this simple approach. In fact he says it's more reliable than using a header tank. I'n not sure about that though and will probably fit one for more peace of mind.

I've had a hard time justifying the added cost of a UAT as opposed to a simple header tank. I really don't see the difference if you consider the header tank fuel to be unusable.

Attached is a picture of my home made clunk.

PST and AMT engine performance.
 

I do something very similar to Marc's. See the article at http://www.jetpilots.org/how_to_buil..._pleated_p.htm

Easy to build and bullet proof!

PST and AMT engine performance.
 

Guess where I got the idea !! Just proved it with two more good flights this morning.

PST and AMT engine performance.
 

Well it seems the jury is divided !

On one hand the evidence suggests that the UAT can, in certain circumstances, cause the very problem it is intended to prevent. On the other hand the simple header tank has worked to absolute perfection on my heavy metal with big engines, even when doing downward vertical rolls with the F4. (honest, its on video !)

On these I use simple clunks weighted with lead to ensure they sink in the fuel. In the refuelling line I use both a Festo and JetCat filter and after examining the airborne filter screens under a magnifying glass they are virtually spotless suggesting the tanks are clean too.

After some thrust pulsing and an unexplained flameout on the RAM 500 leading to model damage I am going to replace the UAT in my BobCat (now flying flawlessly with its PST 600) with a simple header and then throw it around , prolonged knife edge, spinning and tailslides, and see if any problems are revealed. If it works my UATs are history. If on the other hand any problem is uncovered the UAT goes back in and I will observe the precautions you guys suggest.

I don't use felt or other fancy clunks in the belief that they could deposit fibres in the fuel tanks leading to filter restriction or blockage.

I have emailed BVM for their comments.

With great respect to Mick Reeves he had almost as many flameouts as flights when flying his Javelin, what has he changed or did he accept our recommendatoion of a simple hopper tank ?

My own belief is that the simplest possible system, both in terms of installation and operation, (the simple header is self purging during refuelling) which works to perfection is the perfect fuel system for our needs.

And finally, Tony, there is no way I am going to (or could !) vigorously shake a 35 pound F4 or F15 with the engine running at full throttle just to expel air from a UAT or any other tank !

Comments gentlemen?

BRG,

David Gladwin

PST and AMT engine performance.
 

Hi David,

Check out Mick's web site. This set of recommendations are fairly new and he actually says that header tanks cause problems. Don't neccesarily agree , just telling you what he said!

I do believe in the header tank in theory and will probably install one. I know people have great luck with the UAT but am very sceptical that they are in fact better than a plain old centre pickup header tank. If the pickup is always immerse in fuel , how can the membrane enhance it's effectiveness ?

PST and AMT engine performance.
 

Personally, I suspect that a geometrically centred, sintered-broze clunk mounted on a brass tube in the header will be every bit as effective as a UAT.

- First, it should be impossible for an air-bubble to pass through the centre of the tank.
- Second, the bronze clunk should break up most bubbles if the laws of physics start to bend as your jet approaches the speed of light.

On the other hand, the UAT will continue ot function if you empty the main tanks and start chewing into header capacity. Plus you are part of the "in" crowd because you can say you have a BVM product in your jet.

I picked up 2 UATs this year. One came with the Bandit fuel cell set and I ordered an extra one to try out in my Reaper and Boomerang before it goes into my Renegade.

For me, the jury is still out. I'll fly the UATs for a while yet before it goes into any seriously high-dollar projects.

Regards,
Garrett

PST and AMT engine performance.
 

If you start chewing into your header tank capacity you should rethink your flying time !! Consider the header tank to be unusable and you shouldn't run into problems.

PST and AMT engine performance.
 

I have flown several hundred flights using a UAT in several different aircraft, I initially had problems with with flame outs on take off. I was using a catapult system to launch the aircraft, I would throttle to full power, release the catapult, watch it tear down the field, then cut out, very embarrassing, particularly because I could not stop it until the catapult tension ran out.
I assumed it must be a leak after the uat, but this was only happening on the first flight of the day, subsequent flights were fine. The UAT was mounted horizontally.
I mounted the UAT using flexible Tygon pipes, when I tipped the UAT vertically I was amazed to see a stream of bubbles but only on the first flight of the day.
Since then I have never had a flameout in hundreds of flights but I always tip the UAT to check on pre flight.
It is a good product but I think over time air leaks through the cap seal. If you mount it where you can see and tip it to check, you will not have a problem

Mark

UAT
 

C'mon guys---Use your heads!!! :bananahea Before installing the UAT in the model connect it up to your fueling can (I use the one from The Jersey Modeler) and pump fuel through it while shaking it. Run a BUNCH (highly technical term :D ) of fuel through it until you are satisfied. Of course the return line is connected to the fuel can. When done, plug or use hemostats to keep the fuel from leaking out and install the UAT at your convenience.

The purpose of the membrane is that even if you run the UAT to 1/2 empty the membrane is still saturated with fuel and will continue to provide bubbleless fuel to the engine.

After the UAT is in the model I have never had more than a small bubble in the tank. It is expelled when I refuel. If you have a large bubble or a significant amount of fuel missing in the UAT then there is a plumbing/pickup problem in your system. Are you guys completely defueling your jets after flying? My buddies and I don't and maybe that is why we have never had a flameout related to fuel.

Kevin

PST and AMT engine performance.
 

Or simply build the pleated paper clunk and use a Dubro header and keep an extra $30 in your pocket towards digital servos!

PST and AMT engine performance.
 

Kevin,

I had done that to my UAT and I still got a flameout while taxing on one of the first runs with the UAT installed.

I had also shaken the UAT while the engine was running.

Next suggestion?

I haven't had a problem since, but it did leave me scratching my head as to what more I could have done.

Regards,
Garrett

PST and AMT engine performance.
 

Garrett,

The only thing that comes to mind is that perhaps you had a hidden bubble in a fuel filter? You can get a hidden bubble in the UAT if it is not mounted at least 15 to 20 degrees nose up or vertical. I use the clear fuel filters from Festo. I don't like the JetCat aluminum filters because you can't see into them and many of them are prone to leak. I use barbed adapters (4mm to 6mm) to utilize the clear Festo filters as these filters have barbs with screw on compression fittings for 6mm fuel line. I also use tie wraps on EVERY fuel connection where a barb is used. I have never seen a bubble in the clear Festo filter. The only expanation that I can think of is that you had one last hidden bubble in your system on that first run.

I edited my previous response and added more info.

PS----The Turbine Connection has the Festo fuel filters on sale.

Kevin

It's a Draw!
 

I built up a Kangaroo for my buddy Dave who flew the stink out of it this summer. Although he mainly flew his Blade at Superman, he did fly the Roo and did many vertical negative flicks, followed by chicken flops, and then inverted spins before recovery (ala Dennis Lott)---never has flamed out during these maneuvers. Guess what? I used a round 2 0z Sullivan for the hopper tank with the brass tube centered and no clunk.

In my HotSpot and Bandit, I have used UAT, mounted horizontally in the HS, and about 15 deg tip up in the Bandit. Same angle for the filters, horizontal in the HS, and 15 nose up in the Bandit.
Except for 1 unexplained flame-out after close to 150 flights between the 2 planes, all with vertical flicks, conventional and flat spins, and long vertical downlines with flicks and rolls, the P-120's have never blown cold air out the butt end.

The beauty of the UAT is that it does allow you to drain the very last drop out of your feeder tanks. More than once I have landed with my feeders dry, and my UAT down 50%. Bad flight planning yes, but things like that happen every so often when you try to squeeze every last minute out of good flight, or some bozo stalls his plane on the runway when you are fuel-critical, on short final.

So like someone famous once said "You pays yo' money and you makes yo' pick!"

Just remember that bubbles can miraculously appear out of fluid due to cavitation or overheating a line (vapor lock) and that these little bubble will migrate and appear at the most inoppurtune time and place---at least with my bad luck.

And the UAT won't really get you into the BVM Hall of Fame. It's the product of Jeff Seymour (SWB Turbines), of Mamba fame-to-be, about 40 miles north of here. Jeff says he developed them for his commercial/military installations. BV private brands them for resale. BV has no time for this kind of stuff. He's way too busy building up Super B's, BobCats, and JetCases for all my friends from the U.K that attended FIJR!!! :D

Tom

PST and AMT engine performance.
 

Kevin,

No worries. I'll angle up UAT up a bit further. I make a point of not de-fuelling the model when I am done for the day.

On future installations I plan on making sure the UAT is angled up at least 30-45 degrees.

I may also put a tee in the line between the UAT outlet and the servo-operated fuel-shutoff valve that is required under the Aust turbine regs. This way, I can always fuel the model by pumping through the membrane which should dislodge any bubbles.

On my engine, there are solenoids under the front cover that form a return loop from the engine to the tanks when the engine isn't running. Because of this there is no chance of flooding the engine by fueling it in this manner.

Regards,
Garrett

Different Strokes
 

Another---

Not much of an angle
 

Another:

PST and AMT engine performance.
 

If it is so important to have the UAT angled up why do the BVM drawings for the F16 and F86 turbine conversions., which are on my desk right now, both show the UAT horizontally mounted ?

The more you guys tell me how air bubble problems in UATs can be overcome (angling upwards, purging, shaking, refuelling through the membrane, never defuelling etc) the more you point me towards a simple header because that system requires NONE of those procedures to work perfectly, for me at least.

The UAT actually gives perhaps two ounces more useable fuel over a simple four ounce header. With a fuel load of around 100 ounces thats almost insignificant.

Any comment from BVM an SWB turbines ?

BRG,

David Gladwin

PST and AMT engine performance.
 

David,

Very good point.

Regards,
Garrett

PST and AMT engine performance.
 

I have probably somewhere around 400 flights with UAT's and have YET to have a flameout with one installed......well actually I had a flameout in my Bobcat when I failed to charge the ECU battery. (Verified by the JetCat electronics) I have them installed in my Bandit, Bobcat, and F-4 and all done in different orientations. I am careful to purge them when first installing them and don't drain them unless I am stripping the model down. I also shake the model (YES David you can shake a BVM F-4 that is full of fuel!) I have also flown my Bobcat several times until I had less than a 1/3 of a UAT of fuel left. I won't fly without one. Of course I never flew a DF plane without a hopper tank either.


David Reid

PST and AMT engine performance.
 

David,

Whatever works for you then stick with it!!! ;) I will continue to use a UAT for my own peace of mind because for me it works well. I have not had any of the problems that others seem to have with their UAT. I believe that if you call BVM they will tell you that the optimum position for the UAT is slightly nose up rather than totally flat. I also fuel through the UAT as per the BVM instructions.

I'm also very anal when it comes to filtering my fuel. I have two filters on my fueling can. Another from the main fuel supply in the model to the UAT and a final fuel filter between the pump and the turbine. I have no fancy solenoids or complicated fuel return systems. I want to keep it simple. My fuel overflow/vent line fills my ground run tank when I refuel. I have two fuel cutoffs in the model---one between the UAT and the turbine pump and another between the pump and the turbine. When refueling I close only the valve between the pump and the turbine to not only keep from filling the turbine with fuel but to keep the pump primed. When I'm done for the day I close both valves to keep the pump primed and I block off the vent line completely sealing the fuel system to keep it from "breathing" with changes in atmospheric pressure and temperature. My engine in this installation is an AMT Mercury HP.

Kevin

One more before pulling the plug
 

David, I have an even a simpler setup. No hopper, no UAT. I really do believe these are holdouts from the D/F, skinny-tanks-with-no-baffles days. Tad K. at GWM believes this as well, one of the senior turbine gurus in my opinion.

I bought my first HS from German Jet Team Member, Tom Singer.
He had about 50 flights on it when I bought it. No flameouts. I put on a total of 230 flights on it before losing it to control failure at Scottsdale last January. That's the bird in my Avatar, 2 flights before it's demise.

The fuel system--Coke bottle with Du-Bro clunk. No UAT, no Hopper, no Felt. I could look in the tank and see what the clunk tubing and clunk were up to before every flight, thru the speed brake hatch. That's it! No un-explained flameouts in those 230 flights.

Oh my, another myth exploded!


So save your money----Go Hopper Naked! Save money on the UAT and make a few bucks selling Hopper Naked tee-shirts. Wonder if BV would private brand them?? :p


Enjoyed it------Tom