tassos p

I know, I know Jetcat or Jet Central, Jet Central or JetCat its a never ending story!!!

I myself have many Cats only.

However I was surfing in youtube and came across these tests, carried out in Japan apparently.

The testing conditions seem to be the same but you can't be 100% sure about it.

The results however are VERY interesting.

P200SX > http://www.youtube.com/watch?v=iql73...eature=related Max Thrust 21.15kgs (46.62lbs) @ 2:58min in the video

MAMMOTH > http://www.youtube.com/watch?v=Us7EA...eature=related Max Thrust 20.80kgs (45.85lbs) @ 1:58min in the video

However in the declared values of the manufacturers P200 should have a max thrust of 52lb while the MAMMOTH 48lb.

1st conclusion > both manufacturers are close but not achieving their declared values

2nd (and most important) conclusion > The P200 supposed to have a 4lb max thrust difference from the MAMMOTH. But the difference according to the test is 0.35kgs (0.77lbs).

What's happening????[:@][:@][:@]

TASSOS

SGT.SHAGGY

the mammoth does not and will not leave the manufacturing plant with out putting out its rated thrust of 48 lbs min.

Zagzoo

My Feedback: (28)

I love that 48lbs min!!!!

basimpsn

My Feedback: (5)

Video

andy09776

I have a 58lb airplane with a mammoth on it and the vertical is amazing on it...so as long as it runs the way it is i am perfectly happy with it.

jetmon

Hello Tassos
Unfortunatelly we don't know the ambient temperature in the videos, a 15º celcius diference makes more than 3 pounds of thrust at does levels
Regards

tassos p

For me, even though the readings are only 2.15lbs lower than the declared it is still amazing how MAMMOTH is working in comparison to the P200SX and its also a lot closer to its declared value. It sounds quieter as well. I guess while the airplane is flying in the air due to the higher inlet air flow rate the turbine will produce the missing 2.15lbs or even more. I'm personally impressed with the MAMMOTH.

But even if the conditions and the calibrations of these tests may not be right the test rig is the same.

Anyway people can draw their own conclusions.

Tassos

ken tanabe

Hi all,

I know who tested this youtube's and about each test conditions.

Tested by Mr.M.Tahara who managed Jetset Japan that is RC Jet shop in Osaka.
www.jetsetj.com

And some datails of this test are as folllows,
Test of P-200SX (For Skygate Hawk)
Date:7th July 2010
Temp:31℃
Humi:77%
Press:996hPa
Re:Heavy Rainy day

Test of Mammoth (For SM Lage F-86)
Date:1st Oct 2010
Temp:29℃
Humi:64%
Press:1010hPa

Japanese RC Jet pilot

tassos p

That figures then because the factory test conditions are at 20C I think.

Can someone extrapolate the tested data to the ISA conditions. Perhaps Oli (olnico) can help here.

Tassos

olnico

Hi Tassos.
Although the bench looks very nice on the video, I don't think that the measurements shown are reliable. I have had a look at the designer's website but could not find any details about his test bench. However, from looking at this video:

1) The engine tray is sliding on bushes, not bearings => highly variable friction component, especially considering that the thrust application point is not centred between the bushes
2) The measuring device does not seem to be a proper dynamometer, but rather a digital scale. This kind of device will not output the same precision with a different humidity and temperature condition. A proper dynamometer is calibrated for a given range of temperature and humidity.

Both engines not being centered the same way in the testing device, the bushing friction values are different, thus impending a proper reading on measured trust.

So in my opinion, no conclusion can be drawn by watching these videos.

olnico

Again, tassos:

.The engines are not centered the same way in this test bench, thus probably giving different friction values.
.The measuring device is possibly temperature and humidity sensitive.

So although it is the same measuring device, the reading precision can be very different.

olnico

Factory test conditions are at whatever the day's conditions are. HOWEVER they are corrected to ISA conditions.
I can ensure you that neither Jet Central/ JetsMunt nor Jetcat would let an engine go out of the factory that does not meet the declared thrust after correction.

These are the two most trustful makers on the market from what I have been able to see so far with my tests.

basimpsn

My Feedback: (5)

Sooo can we all see a good engine test VIDEO.

Sorry

Robrow

Here's another for what it's worth http://www.youtube.com/watch?v=1KCnP-ZIniM

Rob.

dubd

Has the mammoth been reliable so far?

tassos p

That's great news because I was a bit dissapointed by JetCat.

But I believe that you are right.

Tassos

basimpsn

My Feedback: (5)

Thats almost 40lbs WOW. What was the max RPM. Thats werid I never seen any (Rhino 170) type engine test run video?.

My opinion

bevar

My Feedback: (27)

I would like to see that test done at Kentucky in July. The numbers are probably higher because of the cold OAT at the time of the Merlin test.

Beave

basimpsn

My Feedback: (5)

Well to be fair that merlin probably running @ 124 to 125k to get 40lbs thrust. I remember Johnny (RIP) did the first set of test on the Rhino from artes jets, get up to 34 # if he move the Max RPM to 120K .

http://www.rcuniverse.com/forum/m_22..._1/key_/tm.htm

ZivBit

Do you guys see the oil dripping from the bottom of the turbine of the p200SX video ? look at 1:33 when it begins...
Exactly what I had in My F-16 which is now back in JC for repair\replacement. That leaves a mess in the plane with potential hazzard.

Ziv

Robrow

The idea of the Merlin/Rhino video is that figures (40.45lbs) can be higher or lower, it is all down to ambient temperature at the time, also rpm and accuracy of the rig. Although in this particular case the temp at the time of running was a little lower than a standard ISO day, but not much, on an 86deg day @ sea level it would be down to around 38lbs.

Rob.


[quote]ORIGINAL: bevar

I would like to see that test done at Kentucky in July. The numbers are probably higher because of the cold OAT at the time of the Merlin test.

Beave


[quote]ORIGINAL: basimpsn
Thats almost 40lbs WOW. What was the max RPM. Thats werid I never seen any (Rhino 170) type engine test run video?.

My opinion

Robrow

Engines have evolved somewhat since 2004, of the 3 runs done that day the one in the video was the highest rpm of 119,600. The other 2 runs were 36.71lbs @ 116,000 and 33.62lbs @ 112,600.

Rob.

Robrow

Engines have evolved somewhat since 2004, of the 3 runs done that day the one in the video was the highest rpm of 119,600. The other 2 runs were 36.71lbs @ 116,000 and 33.62lbs @ 112,600.
[/quote]

The established manufacturers have nothing to be gained by putting out engines that punch below their weight.

Here's another example, QED http://www.youtube.com/watch?v=qtOP5...layer_embedded

Rob.

basimpsn

My Feedback: (5)

Robrow do you want to exchange a Rhino for a Merlin .

Robrow

Sure, but there would be no gain for you

Rob.