louis cypher

There are always going to discussions over which powerplant is superior to the other. Brand "x" Vs Brand "Y". I have seen this many times. O.S. Vs Saito Vs YS etc. Claims, counterclaims. This is not meant to be one of those discussions.

Reading through current threads you see that JetJoe owners are Having trouble either getting engines to run or to run correctly, Jetcat owners are openly saying that the fuel usage figures quoted by the manufacturer are much in error, the fuel being used is much greater than they expected. Another turbine manufacture is having its engines copied and a further turbine supplier is quoting fuel consumption figures that are assessed completely differently to all others.

Is this all acceptable ? It seems you are to take some sort of "Leap of Faith" when purchasing. These turbine engines are the single most expensive piece of equipment you will probably buy in this hobby.

How can you make an informed decision under these cicumstances ?

Robrow

Go down your local jet flying club and have a chat, see what they are flying. Also big meetings such as Long Marston last weekend. You will soon weed out the good, bad and ugly

Rob.

louis cypher

Surely this forum is a better place to weed out the good the bad and the ugly ? It has a far greater and varied input.

Adil Nasim

My Feedback: (61)

Definitely !!

As long as you can get "used to" and "look past" the "Mine is bigger than yours" sometimes.

I think the above advice from Rob is certainly something to SERIOUSLY consider. WYSIWYG !!

Adil

siclick33

I don't really think it is as bad as you suggest. If you look through these forums, the same manufacturers have a definite following. I could give a list of the ones that I would trust but I am bound to miss some good ones out.

There is no 'leap of faith' needed. If you go for one of the tried and tested engines you are guaranteed to get a good one. There are probably more good ones on the market than poor.

When you decide what you want, ask here and you will get opinions. The general trend will indicate good or bad but there will, obviously, be bad experiences out there, even with the best engines. If you visit a jet field a couple of times, you will soon get to see what the good engines are.

louis cypher

As far a i can gather, there are only two turbines that are available in the U.K " Over the counter" and that do not have to be ordered from abroard. Correct ?

weasel33

AMT Netherlands are the RRoyce

just my two pence worth so flame me if you want i dont care

Wayne22

My Feedback: (2)

Fuel consumption is variable and to a large extent controlled by the pilots use of the throttle stick. If you have a thirstier-than-average engine, OR if you fly aggressively, your flights are going to be shorter. In the big scheme of things probably not a real big deal...it's not like we are trying to cross the Atlantic, or anything.

You need to look at the whole picture..including such things as reliability, dependability, service, availablity, manufacturer support, and yes, even price..

John Redman

My Feedback: (8)

The main thing to consider when talking fuel consumption on a turbine engine is how is the throttle managed, what is the ambient temperature, and what is the field elevation. All three of these items will have a dramatic effect on fuel consumption figures. Most fuel comsumption figures given by the various manufacturers are based on a standard day in a test condition.

louis cypher

Should this be all fuel consumption figures by all manufacturers ?

Even so, this would not account for the difference being experienced by some turbine owners from what is quoted in the sales data to what they actually get.

rcguy!

My Feedback: (69)

I have a graduated cylinder on order. 500ml (@16oz). I'll hook it up to my overflow (like a taxi tank) and do an actual measurement for 1minute at full throttle on my P60. I'll video tape it as I'm sure some will "suspect" my figures. I'll do likewise on my Wren 44.

Does anybody know what a "standard day" is? AND what the conversions would be to allow a "non standard" day test to be run?

Stay tuned.

Dave Rigotti

Shok

My Feedback: (28)

Thats how I arrived at my numbers on the P-60

Laura H

They all make their turbines seem better on paper....They are all fighting against one and other to get you to choose their engine.

What they cant put on paper...How unreliable it may be. How quick turn around on repairs etc.
Laura

BlackCloud

My Feedback: (12)

Dave,
Standard day or atmosphere as defined by full scale standards is 15 degrees C (59 degrees F) and pressure of 29.92 inches. 1013.25 millibars.
As far as trying to interpolate your actual air pressure and temperature compared to the standard....good luck....maybe someone can help with that. There are many conversion tables but I haven't come across how to do it for actual comparisons.

Louis,
Just for the record......my truck to carry my jets as well as my trailer were much more money than a turbine Thats the single most costly piece of equipment for me
BC

joeflyer

My Feedback: (48)

In the automotive industry engine output as measured on a dynamometer is corrected to standard conditions using correction factors. Several different methodologies have been developed, which all basically correct for differences in air density. In North America all manufacturers are required to use SAE procedure J1349 for any advertised horsepower numbers.

SAE J1349 corrects to a temperature of 77 F/25 C, atmospheric pressure of 29.235 in. hg/990 mb, and 0% relative humidity. The equation is:

CF = 1.180 x [(990/Pd) x the square root of (Tc + 273)/298)] - 0.18

Where CF is the correction factor
Pd is dry air pressure in mb
Tc is ambient temperature in degrees C

The observed horsepower and torque numbers are then multiplied by the CF. While these factors were developed for use on piston engines they would do the same thing for turbine thrust readings. The aircraft engine industry probably has their own factors that correct to a different set of standard conditions. The above equation could easily be modified for a different set of standard conditions. Perhaps someone in the turbine industry can chime in.

These same factors could also be used to approximate fuel flow differences since fuel flow is proportional to airflow. There is probably a more scientific way to adjust fuel consumption numbers but you would also have to know the fuel characteristics (specific gravity, vapor pressure, etc.)

In doing a web search I found this web site that can calculate the J1349 correction factor for you.
http://wahiduddin.net/calc/calc_hp_abs.htm

Give it a try.

Joe

TREADSTONE

Dave, lets not forget Weight is Weight and Volume is Volume..The specific gravity of Fuel is about 0.76.


Laura nails it down.. ....So lets Get them all to Sing from the same Hymn sheet....A campaign for a Level playing field....

Dave.