Tank size v flight time

[Phil 9]

My new model was supplied with a tank marked up as 260cc and I plan to use my jen 57 engine.

 

the tank looks a little small to me. A larger tank will go in but then it will cover the space for the throttle servo.

 

My question is what sort of flight times can I expect with the supplied tank. I is hard for me to try out first as the tank will dictate the throttle servo position so if I set it up for one tank it will be difficult then to set it up for the other

[Martin Harris - Moderator]

I don't have any experience of J'en engines but I'd expect 7 or 8 minutes from that size engine with that tank.

 

Best thing would be to call JE and check with them.

[andy watson]

	2-Stroke Glow cu. in	4-Stroke Glow cu. in	2-Stroke Gas cc	4-Stroke Gas cc
0.375 oz/min				25
0.5 oz/min				32
0.75 oz/min	.32	.50	24
1 oz/min	.40-.46	.70	32
1.5 oz/min	.60	.90	50
2 oz/min	.90	1.20	64
2.5 oz/min	1.20	1.60
3 oz/min	1.60	2.00
3.5 oz/min	2.00

[andy watson]

That's taken from the OS site- should be good enough for everyone else.

 

So at full throttle you will be using 1.5 oz/min. Your tank is 9oz.

 

So 6 minutes if you fly at full throttle the whole time.

[Peter Beeney]

Phil,

If it’s any help, the supplied the tank on a Boomerang will run an Irvine 53 for 23 minutes flat out all the way in the air.

So, if anyone knows what size this tank is……….?

At a complete guess I’d say about 300 cc?, so on that basis a Jen 57 will run for at least 15 minutes constantly flat out on 260 cc?

One litre of fuel weighs approx. 35 oz; so one cc weighs 0.035 oz; therefore 260 cc weighs 9.1 oz. On that basis my 300 cc tank is 10.5 oz, which seems about right.

Alternatively 1 litre of fuel weighs around 1 kilogram, so 260 cc divided by 28.3 equals 9.1 oz.

So now the question is, how long will the 57 run on a 9 oz tank? Up to 15 minutes is still my guess.

Is any of this old cobblers some use?

PB

[Peter Beeney]

In the light of Andy’s post, which appears fairly conclusive, I’ve measured the Boomerang tank. It holds 9 oz. So that would seems to indicate that the Irvine 53 consumes fuel at the rate of very slightly less than 0.4 oz per minute; and from some other checks I can vaugely remember from the dim and distant, such as a Webra 40, that sounds about right.

PB

Edited By Peter Beeney on 13/08/2011 11:36:28

[Peter Wood 4]

Interesting figures Peter. Your Irvine 53 seems to be more economic than the OS table would suggest.

 

I have an Irvine 53 in a Wot 4 and have often noticed how little fuel it seems to use. Could it be that some engines are inherently more economic than others of a similar size?

 

Now I appreciate that fuel consumption will be affected by factors such as prop size and airframe drag but it would be interesting to see some factual data.

 

Perhaps WOO could write an article on the subject.

 

Peter

[Peter Beeney]

Peter,

I would think that for a similar performance the fuel consumption would be around the same on any of these engines of a similar size. I doubt very much if the mixture in the combustion chamber will change that much.
On the quiet, I think these engines are actually very thirsty. I gather that all alcohol engines are a bit like that anyway, they just rely on getting more fuel into the mixture. If we assume a 10 cc (60) size engine uses 0.5 oz/min and then scale it up, pro rata, 100 cc’s will use 5 oz/min and a 1000 cc lump 50 oz/min; so a 1 litre engine would consume 50 by 60, 3000 oz/hr; divide by 16, 187.5 lb/hr, a pint of fuel weighs (roughly) a pound and a quarter, so divide by 1.25, 150 pints, divide by 8, so that becomes 18.75 gallons per hour.

Using the OS rate of 1.5 oz/min then that would equate to 56.25 galls/hr. That’s if I’ve got all my figuring right here, and that may be questionable.

I’d say that rather than the prop size etc. affecting consumption I’d go for the needle valve. I reckon that if you got this a bit on the rich side these figures would get even higher.

No wonder my wallet seems to be forever slim these days!

PB

[Phil 9]

thanks all for the info. I will go for the larger tank although 8 min flight is probably enough for this model its always good to have a little reserve

[Peter Roberts]

I have a J'En 57 in my Flair Kite and generally manage 12-15 mins flying time with the standard tank supplied. It rarely runs out so could probably do a few more minutes too.

I also use a Genesis pipe with the engine.

 

Hope this helps

 

 

Peter

 

[Phil 9]

thanks Peter but I dont know the kite tank size.

 

I have the super quite silencer fitted to mine