in the 14 to 18 lbs range,what turbine has the best mileage??

KingTech K-80

my P-70 is very economical on fuel, the Wrens are good to.

Kevin

Despite the dealer recommendations, the HAWK has the BEST fuel economy.

Now if you ask what has the value...another story entirely.

Dave "not a dealer whatsoever" Rigotti

i would think Jet Joe is by far the most economical with fuel, one tank will last the entire life of the turbine

How far does a Workmate go on a tank with a JJ?

Dave

just as far as you can throw it

well I dont know anyone flying or even anyone that owns one so I cant comment.

I but I have flown just about every manufacturer except AMT.


The P70 does great on fuel burn.
My P60 is a hog.

We put the K-80 in a plane with almost 100oz of fuel onboard.
I set the timer for 7 minutes.
I flew many high speed runs and few aerobatics.
We landed at 7 minutes and still had half a tank.

So take from it what you want, but thats an actual real world usage.

RCJI Says:
Hawk 100R 22# @ 9.8oz per minute
Wren Super Sport 17.4# @10.6oz per minute
Behotec J66HP 19# @ 11.3oz per minute
K80 18# @ 11.8oz per minute
JetMunts 90 21.5# @ 11.9oz per minute

Numbers as published in RCJI Oct/Nov 2009 page 76

Just think how long you could go with a Hawk installed instead of the K80!

Dave Rigotti

I guess I may never know

thanks

Well I haven't flown my new Jet Central Rabbit yet so do not have any first hand real world experience but the manul lists the thrust at 19 lbs and fuel consumtion at 7 oz/min under average use. A couple of folks that I have talked to that own this turbine say it is right in the adverized range.

Absolutely, positively, categorically NOT THE K-80.

I refer you to the table in the back of any recent RCJI mag. The K-80 tested did rather poorly in that department, nevermind that it weighs nearly a POUND more than some of it's competition. There are claims that the oiling system has been revised to lower the fuel consumtion since that time. Could be so. Perhaps Shok is flying a newer variant which is vastly improved over the engine that Kingtech supplied to RCJI for testing?? Although the K-80 is very inexpensive, and the $$ saved at purchased will buy lots of kero, I'd want to see some independent data before making that leap. I'm also very wary of "average use" numbers because there are simply too many variables.

Get a copy of RCJI mag and read the stats. You will find several engines which offer 10-25% better tested fuel efficiencies and weigh a LOT less. This means lower gross weights and/or longer flight times. I assume that any of us spending crazy $$ on toys are interested in fuel burns as related to weight/performance issues rather than economy?

Take a look at the Wren SS and Merlin 90 in particular. The Merlin 90 is higher than your thrust range inquiry at 21+ pounds but still weighs only 3 lbs vs the K-80 at 3.9. It sips fuel, burning 1/10 of 1 ounce (!) more fuel per minute than the K-80 tested, while producing 3.5 pounds more thrust.


ABSULUTE fuel burn per min is not the measure you want. What u want to know is the fuel burned per unit of thrust. RCJI's efficiency index gives you that number so that u can more readily convert an apples/oranges comparison into an apples/apples comparison. It allows you to estimate how much a more powerful engine would burn if throttled back to equal the thrust rating of a lesser one, for instance, as opposed to just looking at what they will all do flat-out.

These ratings allow me to compare, for instance, my guzzling P60 to the Merlin 90. At first glance, since the 60 burns 9.5 oz/min @ 13 lbs thrust, compared to the Merlin 90's 11.9 @ 21.5, it seems as though the 60 "burns less". Nope. The efficiency index numbers indicate that the 90 burns 25% less fuel at comperable thrust settings. The 90 burns 25% less fuel at the P60 13 lb thrust rating, or it makes 17 lbs of thrust on P60 gas. Take ur pick. I have a scratch-built/kit bash jet with a P-60 which averages 6 oz/min on a normal flight and 8 when the hammer is down. In theory, then, a 10 minute fuel load would weigh approximately a pound less if I switched to a Merlin. Hmmmmmmmm.

Here are some interesting efficiency ratings. The lower the #, the better:

Merlin 90 (.050)
JetCat P80 SE (.051)
Wren SS (.055)
K-80 (.059)
P-60 (.066) :-(

A close cousin of the Merlin is the Jet Central Rabbit. They share a lot of common parts and have similar performance, but I have not seen independent tests.

I don't care who u are, THAT is hilarious!!

Im actually using the motor and I see the fuel burn, and your referring me to the back of a magazine that says something totally different than what I am seeing.

What should I believe?
Maybe you are right, mine might be newer not sure they made improvements already though, my motor is about 2 months old

I dont know what to tell you, mine burns nowhere near 12oz a minute

Hawk turbines seem the most economical, a local flyer with a wren 54 seems to be burning much more fuel than a P70 in the same model, looking through the FOD screen I dont see a restrictor in the lube line so maybe it is consumming more because of that.

[sm=thumbs_up.gif] +1

LDS, a K-80 dealer, is offering this engine as a package deal with the Jetmach SS. You are at least somewhat affiliated or at least very friendly with LDS and the development of the their Jetmach SS, are you not? LDS is also a supplier of the SHOK JET, as I recall.

On the other hand, I have data from an INDEPENDENT source which states that the engine is both heavy and a fuel hog. This is the SAME magaizine, by the way, which put the word out that Kingtech hoped to lower the fuel consumption in later serial numbers. So if you want to discount RCJI's credibility, then let's do that and assume that KingTech did NOT respond to the feedback from the tester in an effort to improve the engine, shall we?

So, who should I, (or anyone else) believe? You, or the contributors to the mag? I've never broken bread or even met any of you personally. I will assume that RCJI's contributors are unbiased unless you or someone else can show me otherwise. Perhaps you are completely unbiased as well. And for all I know, the latter K-80's are so efficient that they actually MAKE fuel while airborn. But data from one flight consisting of "many hi speed runs and a few aerobatics" in an un-named airframe of unknown weight in un specified conditions is hardly an in-depth review upon which a multi-thousand dollar comittment should be made.

That you are not personally observing 12 oz/min fuel flows in your jet is neither surprising or relevant unless you are starting the engine at full throttle and leaving it there until the fuel is exhausted. 12 oz/min is what the test engine burned at full power.

Check out SIMJET.. they are probably the best for efficiency...

I never said RCJI was not credible.

Im just relaying my experience.
Yeah I sell KingTechs, I also sell JetCats and on a few occasions setup sells for JetCentrals.

If I was really biased I would tell you how unbelievably awesome all JetCats are, because I make more on a jetcat sale than I do a KingTech.

But in reality, our P70 bought us about 5.5 minutes on around 70oz flying.
The KingTech has the potential of around 12 minutes flying on a 100oz

spin it anyway you want.
Im not trying to sell you anything

K. I cede the point, based on your personal experience with that airframe, that the K80 is more fuel efficient than the P70.

Perhaps you could send a new motor to Olivier and Tom for re-analysis? I imagine they would welcome the opportunity to re-check the flows and ammend their thrust to weight ratio and other comparisons to the other 10 or so motors on either side of the K80's thrust range.

And for the record, I hope the K80 comes out on top, as you asserted in your post above, and that you sell a thousand of them. A new motor on the block that whoops up on all of the others, er even comes close, is good for all of us on the consumer side. Especially given the K80's low price !

I am new to turbines but I must have a fuel miser in my wren 54III. I have it in a LDS sport mach 60 that weights 20lbs dry. I have a 64oz tank and a bvm uat. We have clocked this jet thru 10 passes at 142 to 144 mph. My timer is set at 7min 30 seconds and when it goes off I then start setting up for landing and normally do 2 passes before landing. I have never been into the uat after taxing back to the pits. Maybe the efficiencyof the LDS sport mach 60. Btw, by my best measure witn the scales I have my wren 54 puts out 15 lbs thrust. I am a 66 year old kid just now getting into jets and have no tie with anyone but this jet is a great first turbine plane for anyone that can get a waiver. Flys like a pattern plane out of the 70's. Kenny aka chilechopper

Its hard to compare installed numbers. the flying style and speed/throttle settings vary too much. If you put all those motors at a specific thrust setting, we could see the efficiency better. It is hard to see the actual difference between a ..05 and .06 specific.. Also atmospheric conditions factor in alot.

I take off, fly full throttle for 3/4 of a flight, land at 6 min and burn 50 to 60 oz in my super sport. not counting taxi. that would suggest that in my elan, I average about 9oz a min flying balls to the wall and landing normally. I would bet that most of the small block motors are similar.. Thats at 18 lb thrust. PUt them all at 18, and I would bet the difference would be in the oil bypass give or take...

Pick the motor you are most comfortable with and what the guys around you are running and familiar with. My experience is with Wren, I would look at reliability, dependability, service, how well it starts and accelerates, and who is teaching you, as major factors in selecting your smallblock motor

Why? Am I missing something? The curves I've seen are fairly linear and .05 vs . 06 seems like a pretty straight forward difference of 20%. That's a full pound of fuel less per 10 minute flt for a Merlin 90 (which I have on the way) over my P60 if I stay out of the throttle and don't use those 8.5 extra ponies that are available (yeah, right)

More likely, I will hammer it some and enjoy more performance for the same weight carried aloft in fuel.

I agree completely about the difficuly in comparing installed numbers though. Too many variables, even from flight to flight for the same model on the same day.