It means:
Power told by the manufacturer
Power at the propeller
Net weight (I suppose with all accessories including exhaust line and engine mount)
Cooling system (Wasser = Water. Luft = Air)
Weight / Power Ratio
PS is HP.
Weight and Power of UL engines
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MYR
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Weight and Power of UL engines
I have found this on a german website
Sorry for the low quality of the picture
It means:
Power told by the manufacturer
Power at the propeller
Net weight (I suppose with all accessories including exhaust line and engine mount)
Cooling system (Wasser = Water. Luft = Air)
Weight / Power Ratio
PS is HP.
It means:
Power told by the manufacturer
Power at the propeller
Net weight (I suppose with all accessories including exhaust line and engine mount)
Cooling system (Wasser = Water. Luft = Air)
Weight / Power Ratio
PS is HP.
I'm a French speaking person. Sorry for the mistakes I can make.
If you don't understand what I say, do not hesitate to tell me.
Je fréquente aussi le forum : Le forum des ULM-ELA-LSA
If you don't understand what I say, do not hesitate to tell me.
Je fréquente aussi le forum : Le forum des ULM-ELA-LSA
Re: Weight and Power of UL engines
I am surprised by the Jabi figures. You would think the engines being direct drive, i.e. no gearbox, would produce the same power as on the crank.
Greg Perkins
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KFA
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Re: Weight and Power of UL engines
Agree with you. Crank and prop flange the same thing
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justin.schoeman
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Re: Weight and Power of UL engines
They reduced the prop RPM to give the bad figures. Don't know why they chose 2700rpm, as that is even below the recommended cruise RPM, never mind max continuous RPM!
Continuous power (at the prop) rating for modern Jabiru engines is 83hp and 115hp (possibly 107hp - sources differ) respectively.
Continuous power (at the prop) rating for modern Jabiru engines is 83hp and 115hp (possibly 107hp - sources differ) respectively.
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MYR
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Re: Weight and Power of UL engines
That's the reason why it would be interesting to organise a dyno test.
The Jabiru curve shows that at 2700 rpm the power is 57 kW or 76,4 hp.
This above table shows that at 2700 rpm the power is 63 hp. (17,5% less that it would be).
An engine manufacturer (don't ask me which one !) told me it is 65 hp (but he is not very talkative I don't know at which rpm he took the measurement).
These tests were certainly done with propellers on. That's why it is only 2700 rpm for the 2200 Jab.
Who owns a good dynamometer ?
The Jabiru curve shows that at 2700 rpm the power is 57 kW or 76,4 hp.
This above table shows that at 2700 rpm the power is 63 hp. (17,5% less that it would be).
An engine manufacturer (don't ask me which one !) told me it is 65 hp (but he is not very talkative I don't know at which rpm he took the measurement).
These tests were certainly done with propellers on. That's why it is only 2700 rpm for the 2200 Jab.
Who owns a good dynamometer ? I'm a French speaking person. Sorry for the mistakes I can make.
If you don't understand what I say, do not hesitate to tell me.
Je fréquente aussi le forum : Le forum des ULM-ELA-LSA
If you don't understand what I say, do not hesitate to tell me.
Je fréquente aussi le forum : Le forum des ULM-ELA-LSA
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justin.schoeman
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Re: Weight and Power of UL engines
A dyno won't help at all. All of the published figures are dyno figures, and they will be pretty accurate.
What is really needed is some sort of comparative propeller efficiency test. But that is extremely difficult, as the fuselage shape (up to one prop diameter behind the prop) has a huge effect on the prop efficiency. So for some airframes, you get very good efficiency, even with a short, high revving prop, while for others youe NEED a long, low revving prop.
There is no magic 'this engine is better' measurement. About the closest you can come is to say 'for this particular airframe, this engine gives the best performance'.
What is really needed is some sort of comparative propeller efficiency test. But that is extremely difficult, as the fuselage shape (up to one prop diameter behind the prop) has a huge effect on the prop efficiency. So for some airframes, you get very good efficiency, even with a short, high revving prop, while for others youe NEED a long, low revving prop.
There is no magic 'this engine is better' measurement. About the closest you can come is to say 'for this particular airframe, this engine gives the best performance'.
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