The Cougar is ready.....however, I need opinions on the pipe. The pipe was round when it was installed, now its all warped after three seperate taxi/range tests. There were no hot starts. The fuselage stayed fairly cool around the pipe and turbine areas during and after taxi tests. Do you think I should fly, or should I follow my gut instinct and order a new pipe? This is my first scale jet and weathering job. It was fun assembling this model.

I'd speak with Eric at Jet Central, but no I would not fly it. What turbine?

Dave Wilshere

ABSOLUTELY NOT!

Contact Eric, I'm sure he will take care of it.

David S

No way! Don't risk your jet. Take their advice and get a new pipe. That should not happen under normal circumstances.

Definitely replace it. that pipe looks BAD, but what a gorgeous model - nice job !

Definately a NO-GO!!!!
Is the distance between turbine nozzle and pipe correct?
Very nice Cougar by the way.

nice job on the weathering. get a replacement pipe either from the company or Tam

good luck with the maiden. i got to see one in tucson last week that flew great

Thanks for all the replies guys. Dave W, I have an RTI turbine in it. The distance between the end of the tail cone and the bellmouth is 3/4 inch. The pipe is coming out tomorrow. Eric has always done right by me. I know he will set me up with a new pipe. These der jet cougars are a great value for the first time scale modeler. They have alot of potential. Thanks for all the complements. Alex.

Dang! Nice looking jet! Love the weathering.

wow, I've never seen a pipe warp like that! You sure it's made of stainless LOL!!!!!! geez, either that is one bad bad pipe, or your engine is running twice as hot as it should be! Nice looking plane though!

No definitely dont fly or even run the turbine again with that pipe it's toast. It does look like you have some overheating issues occurring that 'may' have to do with the turbine/pipe installation?? I would like to see an over head view of your engine bay install/layout as it has been running to see if there is any obvious clue's causing latent heat build up. Airflow or lack there of directly around the pipe and at prolonged idle RPM could well be the cause at a guess? Keep an eye on and check any wiring and/or linkages etc. that maybe directly above and in close proximity to the pipe along its length. Really need to see an over head view of the turbine set up...

Cheers- Marty

It is very thin stainless. Compared to the pipe in my lightning, its pretty thin and flexible. I just checked my ecu. My idle temp is 460 F and my full throttle temp was 668 F holding the jet back and running full throttle for about 30 seconds. Thats pretty normal for a 28 lb turbine. I am never in a hurry to maiden a jet, so I definitely want to make it right.

here a couple from after the taxi test. A couple more coming in a bit.

As requested, fresh of the camera.

Great job on the install, The Cougar looks great.
You need a new pipe.

Alex,

I would think the engine is too close to the pipe. I'd move it out a bit more.

Beave

Agree with Bevar, I'd suggest 25-35mm gap from the end of the tailcone to the front of the bellmouth, and also make sure there is some way to get additional cool air drawn in to the space between inner and outer.

Depending on the install, I've seen a lot of guys open up a set of vents in the belly of the jet just ahead of the beginning of the outer tube, you can make them with the NACA vent opening shape and it even looks cool :-) I did that on my Yellow F-15 and F-18 setups. Perhaps not needed in your setup since you don't have a bypass...

Dave

I would paint some BVM Heat shield around the exhaust area. Nice looking plane!

Peter D

Both good suggestions, I think I will start with moving the pipe further from the tail cone. 30 mm sounds good.

RC man, the exhaust area looks charred but its actually pencil lead that I used for weathering, it gives a sheen. I also used high heat bbq flat black paint on the inside of the rear fuse and former. It really isn't getting terribly hot back there. I felt for warmth during the run up and taxi test, the fuse was barely warm to the touch. I just think the pipe is too thin.

Good luck on the maiden!

I may be talking out my *****, so others should chime in if need be and correct me... I see a slight potential problem, the pipe mount tabs have just one screw on each tab.
I think it would be wise to add a second screw to each as this would stop any side play that may happen gradually over time and cause a hot spot in the pipe.Up and down play on the pipe should be non existent as well.


One tail shot (first pic) looks good as far as pipe & engine alignment, but the second *appears* to have the engine askew a touch by way of looking at the tailcone/turbine wheel vanes.


BTW, the jet looks fabulous![8D]

Mike your'e absolutely right about adding another screw to the tail pipe mount. Just overlooked it. Excellent observation on the tail end view. I looked at that pic 20 times, didn't catch that. This is great! Sometimes it best for someone else to look over ones plane. Thanks.

man order the pipe pleeeezzzz! be grounded till proven pipe is installed and taxi checked again to ensure same issue does not arise again and to check all system functions as well.do not skimp on a great model,time and money invested.

Throw pipe away-Gap looks way too small-move it out to an inch or inch and an eigth. Beautiful airplane. great job. Scotty

i agree, you should increase the gap by one inch , and also open vents in bottom of wing , as well as new pipe . creating more air flow at cooler temps ,then u can push tin . as in {neg g} you gotta push the g in jets .

a buddy of mine has a dual f 15 turbine , fat pipes jets rock !!!!!!!