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-   -   jet cat (https://www.rcuniverse.com/forum/rc-jets-120/592853-jet-cat.html)

mat 03-01-2003 06:08 PM

jet cat
 
what is the maximum thrust I can get from my Jet cat 120 if I am able to tweak the computer hardware and will it burn the compressor ?

PJFaller 03-01-2003 09:32 PM

jet cat
 
Just thought I would add my two cents worth about tweeking and turning up tubine engines. Anytime you turn the engine faster to put out more thrust you are shortening the engine life, and you are running the engine hotter. For instance I fly for the airlines for a living and here are some facts that we live by. In the 35 odd years my company has been running jet engines on all aircraft from 737 to 747 we have NEVER thats right NEVER lost an enigne on takeoff at a reduced thrust setting. Reduced thrust operations of a jet engine extend the engine life tremendously. The hot section runs cooler and the shaft and blades dont get as hot as well. My thoughts in my super bandit is to run a p-160 turned way down to 26lbs. The engine will never run hard and should last me a heck of a lot longer. I dont know much about turning enegines up as far as they can go with microturbines, but they are the same thing as the ones putting out 60,00lbs of thrust, and we are told never to run them that way....My two cents take it for what its worth.

Pete

shonny 03-02-2003 02:04 AM

jet cat
 

Originally posted by PJFaller
Just thought I would add my two cents worth about tweeking and turning up tubine engines. Anytime you turn the engine faster to put out more thrust you are shortening the engine life, and you are running the engine hotter. For instance I fly for the airlines for a living and here are some facts that we live by. In the 35 odd years my company has been running jet engines on all aircraft from 737 to 747 we have NEVER thats right NEVER lost an enigne on takeoff at a reduced thrust setting. Reduced thrust operations of a jet engine extend the engine life tremendously. The hot section runs cooler and the shaft and blades dont get as hot as well. My thoughts in my super bandit is to run a p-160 turned way down to 26lbs. The engine will never run hard and should last me a heck of a lot longer. I dont know much about turning enegines up as far as they can go with microturbines, but they are the same thing as the ones putting out 60,00lbs of thrust, and we are told never to run them that way....My two cents take it for what its worth.

Pete

&nbsp
Oh, at last a voice of sanity!

B58 03-02-2003 04:17 AM

tweaking
 
After 23 plus year in the airforce I can add my 2 cents also. The J-57 on the B-52 was the same engine as used on the KC-135. On the buff you turned it 100%, and the engine pressure ratio was reflecting that. We never ever lost an engine on takeoff. On the KC the engine was pushed to about 104%, epr reflecting the added boost, and I can remember several times we shelled an engine on take off roll. The guys that design and test these things usually know what they are doing. If you want more power, just get a more powerful engine. It lives longer, costs less, and you will have a plane that will be around longer. Just my two cents worth. Oh, on the B-58 normal takeoff was 100% with burner. You could go into overspeed and push it to 103%, but it better be for a good reason.

jayman618 03-08-2003 02:10 PM

jet cat
 
I agree!

unknown 03-14-2003 03:51 AM

jet cat
 
My two cents lol
?What if the engines is identical but the difference is in the ecu rpm ?? for example p80 & p120. buying the p120 does not mean you got a bigger engine.

MAT the best thing is to do some research on the smaller engine compressor and turbine wheel size and compare it to the higher
thrust engine. If its the same then the difference is in the ecu.

You can play with the ECU rpm limiter circuit.

tedeb 03-14-2003 08:37 AM

jet cat
 
I also fly jets for a living. One thing we all do , and that is we look after our engines. Reduced thrust takeoffs where we can. If you are flying off a half decent runway you will not require full thrust for takeoff. That is of course if you have matched the right engine to the right airframe. My Jet cat 120 never gets near max thrust for more than 5 secs.

rhklenke 03-14-2003 02:33 PM

jet cat
 

Originally posted by unknown
My two cents lol
?What if the engines is identical but the difference is in the ecu rpm ?? for example p80 & p120. buying the p120 does not mean you got a bigger engine.

MAT the best thing is to do some research on the smaller engine compressor and turbine wheel size and compare it to the higher
thrust engine. If its the same then the difference is in the ecu.

You can play with the ECU rpm limiter circuit.

Actually, from talking with Bob Wilcox, the P-80 and the P-120 are NOT identical engines except for the ECU RPM. The P-80 and P-120 are the same physical size, but they have different diffusors and turbine wheels. I had a P-80 that produced 18 lbs of thrust at 120K RPM. I replaced it with a P-120 which I am running at 115K RPM and getting 22 lbs of thrust - clearly, these are not the same engines and size is not the ultimate determiner of thrust.

Bob

lov2flyrc 03-14-2003 02:46 PM

jet cat
 
Bob is correct.... The P-120 and the P-80 are NOT the same engine. Jetcat designs each engine from the ground up. Unknown is correct though as some manufacturers in the past have labeled (rated) engines depending on how well it performed after assembly and then sold it as Model "A" or Model "B".

Todd

cairoman 03-14-2003 03:13 PM

jet cat
 
The newer generation turbines (Jetcat P120 - BTW, I own one, ask Spiderjets, he sold it to me- the Simjet 2300, 3000, TJT 3000, AJ JG100 Eagle, etc, etc.) have twelve vaporiser sticks in the combustion chamber, as opposed to six in their older less powered brothers.That's what makes them more powerful. Also, they feature different compressors, diffusers and shafts/shaft tunnels as well as more sofisticated exhaust cones. Not a lot has been invested in the rear parts except in the case of TJT/AJ where the turbine wheel has been completely re-designed.

BRG,
Chris

unknown 03-14-2003 03:36 PM

jet cat
 
Guys i am just using jetcat engine as a example. I only have the
p80 engine. Tod you got the idea that why i wrote if you want to experiment with more thrust do the research first. But do you notice that jetcat p80 tail cone is shorter than the p120 ! remember the first set of ram 750 use the short cone and when they came out with the 1000 the cone get taller. Some thing is similar with the jetcat. is it that the smaller cone only can produce
limited amont of thrust?? just wondering.

(Quote from artejets.com) :rolleyes:
Is not a secret that almost everybody has based or copied our models at the same time they have used the latest improvements we are developing. We wish sometime they'll be able to develop some other improvement for all of us. pirate:

lov2flyrc 03-14-2003 04:39 PM

jet cat
 

Originally posted by unknown
Guys i am just using jetcat engine as a example. I only have the
p80 engine. Tod you got the idea that why i wrote if you want to experiment with more thrust do the research first. But do you notice that jetcat p80 tail cone is shorter than the p120 ! remember the first set of ram 750 use the short cone and when they came out with the 1000 the cone get taller. Some thing is similar with the jetcat. is it that the smaller cone only can produce
limited amont of thrust?? just wondering.

(Quote from artejets.com) :rolleyes:
Is not a secret that almost everybody has based or copied our models at the same time they have used the latest improvements we are developing. We wish sometime they'll be able to develop some other improvement for all of us. pirate:

Unknown,
If I understand things correctly..... The tailcone is tuned to the turbine like a tuned pipe is tuned to a 2 stroke engine. If the the cone diameter or length is "off" the engine will loose thrust and will also raise / lower the egt. I am not an expert on this by any means, I expect there are others with extensive knowledge that can explain things further. I can however confirm that the P-80 and the P-120 are almost entirely different engines.

Todd

Woketman 03-14-2003 05:37 PM

jet cat
 
"the first set of ram 750 use the short cone and when they came out with the 1000 the cone get taller". That is not true. Many RAM 750Fs had the long cone, but more of them did indeed have the short cone also.

rhklenke 03-14-2003 08:31 PM

jet cat
 

Originally posted by unknown
Guys i am just using jetcat engine as a example. I only have the
p80 engine. Tod you got the idea that why i wrote if you want to experiment with more thrust do the research first.

[snip]

The point with respect to the original question is, you are not going to be able to get P-160 level thrust out of a P-120 simply by turning up the maximum RPM - they are totally different motors. At best, by going above the max. allowable RPM for for the P-120 you'll get 2-4 lbs more thrust at the expense of greatly reduced engine life. This is the best-case scenario, in the worst case, the engine will destroy itself as its not balanced for operation much above the max. limit and the higher temp. may destroy it too.

If you want more than 26 lbs of thrust, get a P-160...

Bob

Woketman 03-14-2003 09:09 PM

jet cat
 
Or a TJT 4000 Condor. Should be available soon.

unknown 03-14-2003 11:30 PM

jet cat
 
yes i think the tail cone tune the output thrust power but i think the manufactures use these shorter cone as a limiter also . because both cone size work well on the 750 for example but the shorter one can not put out over 20 lb thrust even with the same compressor and turbine wheel as p120 or the p160 . its like the nozzle on a garden hose difference in velocity.
Any power over 23 lb uses the longer cone. am i the only
one noticing this. Any engine over 34 lb i can,t gave my opinion
on because i never disassemble that size before but the others
i did. My territory on this subject is modifying these parts can give
you the same result as the factory designed


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