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Old Nov 29, 2012, 03:58 AM
310mph Kolibri T25 Swist
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Sverige, Kronobergs Lšn, Ljungby
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Kolibri T25 and P20SX thrust test

P20SX tested in our test bench. Ambient temprature of about 10 Celcius.

P20SX thrust test (3 min 35 sec)



Another Kolibri T25 tested at the same time as the P20

Kolibri T25 thrust test (1 min 13 sec)


Things I noticed is that the solenoid valves are exactly the same, JC has only glued two of them togeather. Fuelpump is exactly the same too, but JC has their bus sytem mounted to the pump. The installed weight of the P20 is 150grams heavier then the Kolibri. Both of the tested engines started and ran as expected with no problems. The Jetcat install looks alot messier then the Kolbiri due to twin fuelvalves, alot of adapters 3-4mm Festo, 2-channels for engine controll, the need for a 1.2meter(4ft) coiled fuel line between enigne and pump etc.
















The cone is off center by about 1mm. Again not my engine so I'm not fiddeling with adjusting it. Probably easy to do.

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Last edited by henke; Nov 29, 2012 at 04:47 AM.
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Old Dec 02, 2012, 09:03 AM
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Old Blighty
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Many thanks for doing this comparison and sharing your data. So, the T25 is smaller, lighter, produces more thrust and is a neater install than the P20 - sounds like a clear winner to me!

I was (and still am) interested in buying a T25, but decided upon the P20 because I was concerned about the lack of support for the T25. I emailed Martin Lambert twice before making my decision and got no response. What do you do with the T25 if you have a technical query or it requires servicing??

I have very recently maidened what I believe to be one of (if not THE) only jet powered flying-wing using the P20! That said, if anyone has a T25 for sale or knows where I can get one, please let me know.

Jet turbine Flying Wing (RiteWing ZII - aka "Project Hello Kitty") (5 min 41 sec)
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Old Dec 02, 2012, 11:29 AM
310mph Kolibri T25 Swist
henke's Avatar
Sverige, Kronobergs Lšn, Ljungby
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Quote:
Originally Posted by Ian Davidson View Post
I was (and still am) interested in buying a T25, but decided upon the P20 because I was concerned about the lack of support for the T25. I emailed Martin Lambert twice before making my decision and got no response. What do you do with the T25 if you have a technical query or it requires servicing??
This is always an issue no matter who you buy from. If you call Martin he answers 8 times of 10 and is happy to help, email are rarely answerd. He speaks English very well. I also know that CS turbine service in Sweden are servicing Kolibris now. I have no experience with Jetcat, I just know delivery times are long some times. For service I do not know.

As for the test the most important thing is that both units do run perfectly well, so two winners :-)
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Old Dec 02, 2012, 11:39 AM
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Henke, you're the most experienced person I know on the T25 turbines, so your opinion means a lot! I guess the one advantage the P20 has over the T25 is the kero-start. Does the T25 offer this too now, or do you still need to start off gas?
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Old Dec 02, 2012, 11:58 AM
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Quote:
Originally Posted by Ian Davidson View Post
......

I guess the one advantage the P20 has over the T25 is the kero-start..........

Actually... to me it's not an advantage. Especally on a small engine. It's simply the newer tech.

So, why you may ask??


1) The Kero plug takes a lot of power to heat up. On a small engine, that's a HUGE negative. (since it's going to be in a small model) That means you need a 1Lb battery with the P-20, where the little Kolibri is perfectly happy with a small, light LiPo battery. (800 mah, 2s LiPo)

2) I've watched a few Kero start engines not work properly... and when that happens... you get a flamethrower. (if you are lucky) If you aren't lucky... you get a bunch of fuel in the model, and when it lights... you get a fireball.


Until it's fool proof... I'm not going to buy a Kero start engine.
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Old Dec 02, 2012, 12:37 PM
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I have a Wren 54 helicopter turbine engine on gas start and the P20-SX on kero start. I've found the kero start on the P20-SX to be a lot less fuss than the gas start - especially on very cold days when you often need to 'warm' the gas before it'll start.

As for power consumption, my flying wing only as a 1000mAh 2S battery on board. The glow-plug and starter-motor pull about 9A combined, and since the starting process takes just 20 seconds (approx), it's not an issue.
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Old Dec 02, 2012, 12:53 PM
310mph Kolibri T25 Swist
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I've personally only used gas start and I find it work very well. The kerostart is convinient but it creates alot hotter gasses when starting up (assuming the process does work as it should) which might be a problem in small planes with limited distance to heat sensitive parts. This is partly why we are testing the P20, simply to determine how it would work in a foamie.

I know the comeing Lambert ECU will do kero start too, but I think it's a lot of testing to get it right and if I'm free to guess probably not available to the summer.
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Old Dec 02, 2012, 01:11 PM
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Here's my P20 on a foam wing. As you can tell, it's not a speed-demon (large, thick chord wing - I believe about 130 MPH) - it's been built for FPV.

The flames on start-up in this video were intentionally instigated for 'show' - I don't make a habit of it though

Project Hello Kitty: Auto-start. Spool up to idle. (1 min 0 sec)
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Old Dec 02, 2012, 04:10 PM
310mph Kolibri T25 Swist
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More testing done, this time in cold weather and bright day light :-) Some how the P20 did idle at 113000rpm, but I'm sure that is due to human error from our side and not an engine related issue.

P20SX vs Kolibri T25-HP (9 min 9 sec)
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Old Dec 02, 2012, 04:49 PM
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Awesome video Henke - really informative - loved it! Out of interest, what altitude are you at? That Kolibri T25-HP really is an amazing little beast!

So, from your two videos I noted...

P20-SX - 2380g @ 10'C
T25-HP - 2880g @ 10'C

P20-SX - 2550g @ -3'C
T25-HP - 3430g @ -3'C

Were you are sea-level (although it's all relative), the air-density @ 10'C would be 1.243 kg/m3 and at -3'C it's 1303kg/m3 - or 4.8% denser.

However, the P20-SX yielded 7% more power at -3'C and the T25-HP an incredible 20% more power - this is amazing and bizarre!?
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Old Dec 02, 2012, 05:25 PM
310mph Kolibri T25 Swist
henke's Avatar
Sverige, Kronobergs Lšn, Ljungby
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Quote:
Originally Posted by Ian Davidson View Post
Awesome video Henke - really informative - loved it! Out of interest, what altitude are you at? That Kolibri T25-HP really is an amazing little beast!

So, from your two videos I noted...

P20-SX - 2380g @ 10'C
T25-HP - 2880g @ 10'C

P20-SX - 2550g @ -3'C
T25-HP - 3430g @ -3'C

Were you are sea-level (although it's all relative), the air-density @ 10'C would be 1.243 kg/m3 and at -3'C it's 1303kg/m3 - or 4.8% denser.

However, the P20-SX yielded 7% more power at -3'C and the T25-HP an incredible 20% more power - this is amazing and bizarre!?
This is not the T25 from the previous video. We did however run the other one too a little later that same day at -3C and got 3250grams of thrust.

that same engine is ran at very high ambient temp seen here:

Lambert Kolibri T25 thrust test, ambient temp 27°C/80°F (1 min 16 sec)


Kolibri T25 (exact same engine)
2650grams @ 27C
2880grams @ 10C
3250grams @ -3C

:-)
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Old Dec 03, 2012, 12:58 PM
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Ahh, I see, still it's very interesting - the thrust still increased out of proportion with the air density increase? Please see the table below (sorry, I had to use '.' as it would accept multi spaces).

Looking on Google Earth, I see Ljungby is at about 500ft, so I used this as the altitude.


Thrust.. Temp.... Air Density... Density Inc... Thrust Inc
----------------------------------------------------------
2650g... 27'C.... 1.152 kg/m3
2880g... 10'C.... 1.221 kg/m3... 5.98%......... 8.67%
3250g... -3'C.... 1.280 kg/m3... 2.37%......... 12.8%
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Old Dec 03, 2012, 01:06 PM
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May I ask, what is the diameter of the trust nozzle on the T25-HP?

The diameter of the nozzle on the P20-SX is 25mm and I'm just wondering if by having a slightly larger nozzle, the T25-HP could be creating more thrust, at the cost of exhaust gas speed?

Power = thrust x gas speed, so you could increase the thrust by having a slightly larger nozzle opening, but you would reduce the gas speed.
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Old Dec 03, 2012, 01:51 PM
310mph Kolibri T25 Swist
henke's Avatar
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Quote:
Originally Posted by Ian Davidson View Post
May I ask, what is the diameter of the trust nozzle on the T25-HP?

The diameter of the nozzle on the P20-SX is 25mm and I'm just wondering if by having a slightly larger nozzle, the T25-HP could be creating more thrust, at the cost of exhaust gas speed?

Power = thrust x gas speed, so you could increase the thrust by having a slightly larger nozzle opening, but you would reduce the gas speed.
The nozzle outlet is about the same.I understand from "Frema" that the kompressor of the P20 is smaller, also the turbine have less blades (21 vs 25). The P20 is a basic engine design with a conservative combustionchamber. It all ads up I guess.

500ft is spot on!! Maybe the air moisture adds up too? I'm not that deep in to it, I only know what my test say and that the results are true and not chaeted.

I think with a smaller nozzle you increase the pressure and temp in the engine and making more power at higher efflux.
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Old Dec 03, 2012, 01:59 PM
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That T25-HP is a VERY impressive engine for sure! So who owns the 3430g beast?

Does Martin Lambert understand why his seemingly identical turbines (T25) produce different levels of power?

i.e. T25 vs T25-HP (and two different T25-HP's producing different power outputs as well?)
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