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Jetcat P-80 or P-80SE?

Old 12-31-2009, 06:15 AM
  #26  
Stobe777
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Default RE: Jetcat P-80 or P-80SE?

I thought this same over and over, after flying smaller turbines with lots of rpm and about 80 N thrust. However, I sold them away and got myself a Wren 120. Only a little more expensive than P80 SE. Like P80:s it has small rpm, big bearings but a shorter overall length than jetcat. I doubt I'll ever need 160 N, no budget beyond my Elan now! So what used to be small, light and powerful turned out to be noisy and a bit critical. A low- tuned big block should last better. I lost the handy kerostart, but its not everything. Rather than torturing a small turbine with full power, a bigger one with half or 3/4. I believe fuel consumption is not a lot different, actually it may even be less now.
There are " hot rod " turbines and "agricultural machines". Which one is more reliable...?
TP.
Old 12-31-2009, 06:22 AM
  #27  
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Default RE: Jetcat P-80 or P-80SE?

ORIGINAL: Red B.

I have heard that the old P80 has a spool-up time of approximately 3s. and a slightly shorter spool-down time. Is that in agreement with your experiences?
Red, this is not right. The non SE P-80s have a spool up time between 10 seconds and 6 seconds.
The latest versions had 6 seconds. So the best you can do with an old P-80 is to have it sent to Jetcat and updated to get 6 seconds instead of 10.
The P-80 can be updated to SE version be at a very high cost ( inlet, compressor, combustion chamber, tailpipe and electronic board change ). Almost all the engine components have to be changed...

The new P-80SE spools up in 5 to 3,5 seconds depending on the ECU acceleration setup and atmospheric conditions. If you need more information please refer to my test report in the August/September RCJI publication.

Slowing down a propeller engine is not going to simulate the jet engine properties correctly. You still get the massive washout from the propeller blowing the flying surfaces. This is not the case on a jet aircraft and it is why a slow engine makes the things so tricky: you first have to wait for the engine to spool up, then for the plane to accelerate before you can feel the the difference on a go-around. So imagine if you get caught at too slow speed/high AOA in a tight turn...
Old 12-31-2009, 06:37 AM
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Default RE: Jetcat P-80 or P-80SE?


ORIGINAL: JetCatJimmy

In the future I will plan on sucking it up and going SE or to a similar turbine with a CNC machined compressor blade instead of a cast one for faster spool times
Hi jimmy,
The CNC machined compressor does nothing on acceleration times.
It just makes the compressor stronger and more accurately balanced. Jetcat gets the compressor cast from Germany and get them in a raw state with a much bigger balance ring. So at the CNC machining stage they use the bigger balance ring to 3d balance the assembly. Cutting the raw casting makes things much easier on the balancing stage.

What influences the acceleration times is the combustion chamber design. The chamber has to be able to convert the extra fuel coming to it into heat quickly. If not, the flame might blow out due to the fact that the liquid fuel vaporizes in the chamber first with locally reduces the temperatures around the flame. This is not an exact science since it is very difficult to be able to observe aero dynamical phenomenon at 1000 degrees centigrade ( try to introduce a camera into a combustion chamber ... ). So the experience of the manufacturer is essential here. I must say that Jetcat has found a very effective CC design last year and all the new engines featuring this chamber ( P-80SE, post June 2009 P-60SE, post August 2009 P-160 SX and P-120SX, P-200SX ) are amazing...
Old 12-31-2009, 06:40 AM
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Default RE: Jetcat P-80 or P-80SE?

Hello,

Olnico perfect comments ! +1

Guillermo, 3 sec spool up time for a latest P80 is not right, 6 to 10 is the right figure.

But the P80 spool up time should not be an issue if you correctly manage your landing approach.

If your used P80 is cheap (under 1500$) go for it, if not buy a P80SE. There is a world between them.

Happy new year.

Alain

Old 12-31-2009, 06:43 AM
  #30  
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Default RE: Jetcat P-80 or P-80SE?

ORIGINAL: Guillermo Ibanez


ORIGINAL: cgroen

ORIGINAL: Red B.

I have heard that the old P80 has a spool-up time of approximately 3s. and a slightly shorter spool-down time. Is that in agreement with your experiences?
Absolutely NOT!
The two P80's (non SE) I have owned (bought them new, two years ago), had a spool up time of around 6..7 seconds from idle, and a little faster ''the other way''
I had them in two Baby Boomerangs, sold both engines and mounted P60SE's instead, a world of difference (I would have bought the P80SE if they had been available at the time) for me at that time!
My P-80 is one year old and has the new chip inside and spool time is 3 sec.

I remember older turbines spool time about 6-7 sec.

Guillermo,
Changing the chip will not magically cut the spool up time by two. It will only make the engine cope for higher temperatures during spool up ( ie the ECU will allow higher EGTs during spool up ). Unfortunately, this has a significant influence on the combustion chamber life...
What you are referring to is the latest generation P-80. They changed the combustion chamber design in this engine. This allowed a slightly faster engine.
I had one on evaluation just before getting the P-80SE for testing. It gave me spool up times of 6 seconds and down to 4 seconds on fast/fast with a high idle.

If your P-80 spools up in 3 seconds, then it is a SE version.
Old 12-31-2009, 07:07 AM
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Default RE: Jetcat P-80 or P-80SE?

Go With the SE.....
Old 12-31-2009, 09:20 AM
  #32  
Guillermo Ibanez
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Default RE: Jetcat P-80 or P-80SE?


ORIGINAL: olnico

ORIGINAL: Guillermo Ibanez


ORIGINAL: cgroen

ORIGINAL: Red B.

I have heard that the old P80 has a spool-up time of approximately 3s. and a slightly shorter spool-down time. Is that in agreement with your experiences?
Absolutely NOT!
The two P80's (non SE) I have owned (bought them new, two years ago), had a spool up time of around 6..7 seconds from idle, and a little faster ''the other way''
I had them in two Baby Boomerangs, sold both engines and mounted P60SE's instead, a world of difference (I would have bought the P80SE if they had been available at the time) for me at that time!
My P-80 is one year old and has the new chip inside and spool time is 3 sec.

I remember older turbines spool time about 6-7 sec.

Guillermo,
Changing the chip will not magically cut the spool up time by two. It will only make the engine cope for higher temperatures during spool up ( ie the ECU will allow higher EGTs during spool up ). Unfortunately, this has a significant influence on the combustion chamber life...
What you are referring to is the latest generation P-80. They changed the combustion chamber design in this engine. This allowed a slightly faster engine.
I had one on evaluation just before getting the P-80SE for testing. It gave me spool up times of 6 seconds and down to 4 seconds on fast/fast with a high idle.

If your P-80 spools up in 3 seconds, then it is a SE version.
Hi Oli and Alan:

Maybe I am misinterpreting the spool time concept.

What I mean with 3 seconds, already measured in my P-80 non SE, is the time between the throttle stick full up ant the turbine starting to accelerate. I do not remember if I have measured the time between full thottle up and full rpm.

Would you please clarify me this concept?

This wll make comparison under the same point of view.

Happy new year
Old 12-31-2009, 09:22 AM
  #33  
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Default RE: Jetcat P-80 or P-80SE?

ORIGINAL: madmodelman

I would not even bother with a non SE version, I have both and the SE is a different engine altogether, the spool up is significantly faster and the power noticably greater.

If you fly from a long runway you will get away with a P80 but if you are tight for space an overshoot decision for instance has to be made extremely early to save your model. Is it worth the risk?
I repeat the above, my P-80 was a late version (2345) which actually is rated at 20# whereas the earlier versions were only 18# and, as I said, the difference is chalk and cheese! You are talking about a 20% power increase and phenominal spool up time, even from idle.
The pre SE is great for learning turbine throttle management in say a Boomer Sprint but when you eventually move on to for example to an F16 where the high AOA means decent is controlled more by power management than elevator authority you will be glad you got an SE!
Listen to Olivier.
Old 12-31-2009, 09:56 AM
  #34  
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Default RE: Jetcat P-80 or P-80SE?


ORIGINAL: Guillermo Ibanez


Hi Oli and Alan:

Maybe I am misinterpreting the spool time concept.

What I mean with 3 seconds, already measured in my P-80 non SE, is the time between the throttle stick full up ant the turbine starting to accelerate. I do not remember if I have measured the time between full thottle up and full rpm.

Would you please clarify me this concept?

This wll make comparison under the same point of view.

Happy new year[img][/img]

Ok, Guillermo. Now I understand better your statement. Your are talking about throttle lag. We are talking about spool up time.

Here is how I do the spool up time measurement:

Throtlle at idle. Engine stabilized.
Throttle stick to full thrust= timer started
Engine reaching the max RPM= timer stopped

You are right, the throttle lag was improved with the latest ECU versions. I didn't make a specific throttle lag measurement on these engines but my spool up time measurement includes the throttle lag as you can see above.
Old 12-31-2009, 10:07 AM
  #35  
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Default RE: Jetcat P-80 or P-80SE?


ORIGINAL: olnico


ORIGINAL: Guillermo Ibanez


Hi Oli and Alan:

Maybe I am misinterpreting the spool time concept.

What I mean with 3 seconds, already measured in my P-80 non SE, is the time between the throttle stick full up ant the turbine starting to accelerate. I do not remember if I have measured the time between full thottle up and full rpm.

Would you please clarify me this concept?

This wll make comparison under the same point of view.

Happy new year[img][/img]

Ok, Guillermo. Now I understand better your statement. Your are talking about throttle lag. We are talking about spool up time.

Here is how I do the spool up time measurement:

Throtlle at idle. Engine stabilized.
Throttle stick to full thrust= timer started
Engine reaching the max RPM= timer stopped

You are right, the throttle lag was improved with the latest ECU versions. I didn't make a specific throttle lag measurement on these engines but my spool up time measurement includes the throttle lag as you can see above.
OK

Thanks Oli

Now all of we are talking the same language.

Next time my P-80 is running, I will do this test and post results. Should be the same as yours


Old 12-31-2009, 11:24 AM
  #36  
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Default RE: Jetcat P-80 or P-80SE?

Thank you, Olnico, for the explanation. I thought that the rotational inertia of a cast compressor blade was the limiting factor that slowed down the acceleration and that lighter materials helped the response time.

This is a great thread. Very educational. I know that I have my P80 dialed up to the max rpm. It's impressive what a couple pounds can do for your model. If you have an opportunity to get ANOTHER 2lbs with an SE, I say go for it.
Old 12-31-2009, 01:18 PM
  #37  
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Default RE: Jetcat P-80 or P-80SE?

I'm with falconwings on this one.

If I had to choose between a P80 and P80 SE, I would go with a P80SE. Undoubtedly.

Even for an extra $800-$1000. But that's what I'd pay.

Now, that being said, I would NEVER buy a P80 SE (or regular P80) because a P160SX is the exact same size and it has twice the output!

I would use my thumb, eyes and brain as a thrust regulator

Raf
Old 12-31-2009, 01:26 PM
  #38  
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Default RE: Jetcat P-80 or P-80SE?

I would use my thumb, eyes and brain as a thrust regulator
That's what she said...
Old 12-31-2009, 04:06 PM
  #39  
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Default RE: Jetcat P-80 or P-80SE?

I own 2 jetcat P80Ā“s not SE and I think the spoolup time isnĀ“t a problem, learn to fly whith it and it works great. the thrust diffierence is only 700g when you increase the rpm to 123500 on the p80. Moore reliable engine is hard to find and i stay put whith them because they have never failed me in any way.

But if your flying skills need some improvement then an engine whith faster spoolup time is to prefer

There are Jetcats and their copies on the market today

BRG K-A
Old 12-31-2009, 08:03 PM
  #40  
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Default RE: Jetcat P-80 or P-80SE?

I just purchased a new P-80SE for my Bandit ARF simply because it used to have an old P-80 and all the hardware for it is already there. BTW, it was difficult learning to fly a BARF on a P-80. Mine was really old and was putting out 17lbs on a good day.
However, let me say this with all honesty. Having owned a Jetcentral Rabbit for a while and constantly seeing a friend flying an Evo 90, I have to say that owning a Jetcat again seems like going back to Jurassic times. God I forgot how big that thing was!!. I opened up the box and I was like "did Todd send me a P200 by mistake?".

But I do understand that the price for the newer technology engines is pretty stiff, and the P-80 is still a very affordable and reasonable option.

If you intend on quickly moving to a faster or more scale model soon after your first jet, you may want to consider one of the newer breed of small size/high-RPM engines such as the Evo, Rabbit, or M90.........again not because the P80 is a bad engine but becasue the others are smaller and easier to install.

David

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