Turboprop engine vars
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Brian Franklin
- Concorde
- Posts: 763
- Joined: 14 Jul 2004, 19:42
- Location: Chester / London
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Turboprop engine vars
I want to drop the ground idle rpm for a single engine turbo prop. Anyone know which air file variable does that?
-
Brian Franklin
- Concorde
- Posts: 763
- Joined: 14 Jul 2004, 19:42
- Location: Chester / London
- Contact:
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LoadMaster
- Chipmunk
- Posts: 13
- Joined: 06 May 2005, 06:09
The aircraft may idle at 42% max rpm which should be 0% Throttle.
It doesn't seem to matter what Throttle breakpoints you use in 1503/1504.
I use 0,15,30,45,55,70,85,100 in Rick's Viscount and HS748 aircraft.
The tricky bit is finding the appropriate CN2 values for each of the Throttle breakpoints used.
Using negative minimum Throttle limits on aircraft that don't use reverse thrust is usually seen on aircraft whose maximum torque is excessive to spread the rush of power over a longer throttle profile as in Rick's Viscounts.
Regards
David
It doesn't seem to matter what Throttle breakpoints you use in 1503/1504.
I use 0,15,30,45,55,70,85,100 in Rick's Viscount and HS748 aircraft.
The tricky bit is finding the appropriate CN2 values for each of the Throttle breakpoints used.
Using negative minimum Throttle limits on aircraft that don't use reverse thrust is usually seen on aircraft whose maximum torque is excessive to spread the rush of power over a longer throttle profile as in Rick's Viscounts.
Regards
David
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LoadMaster
- Chipmunk
- Posts: 13
- Joined: 06 May 2005, 06:09
Hi Rick
Hopefully any update of the 748 engines will include 12' diameter props.
Having installed them in my own copies it appears that the taxi speed problem is primarily related to the conflict between the 10' dia props and the gear reduction ratio which is for 12' dia props.
I can now taxi the 748s at the speed of my choice using throttle to control speed (no pounding of brakes required).
My comment about excessive torque results from my having installed all the engines that were fitted to the various Series of the 748 and Viscount aircraft when they were built by using the formula
ESHP - (static_thrust / 2.6) = SHP and
SHP * gear_reduction_ratio * (5252 / maximum_N2_rpm) = maximum_torque (ft-lb).
The only information I have about these engines (except for the Mk.150 and 152 engines in theCC2/CC2QF aircraft) is their EHP figures so for the purpose of the exercise I treated EHP as ESHP which I think gives me a slightly higher maximum_torque than it should be, but substantially less on the Viscounts and more on the 748s than you are using.
Regards
David
Hopefully any update of the 748 engines will include 12' diameter props.
Having installed them in my own copies it appears that the taxi speed problem is primarily related to the conflict between the 10' dia props and the gear reduction ratio which is for 12' dia props.
I can now taxi the 748s at the speed of my choice using throttle to control speed (no pounding of brakes required).
My comment about excessive torque results from my having installed all the engines that were fitted to the various Series of the 748 and Viscount aircraft when they were built by using the formula
ESHP - (static_thrust / 2.6) = SHP and
SHP * gear_reduction_ratio * (5252 / maximum_N2_rpm) = maximum_torque (ft-lb).
The only information I have about these engines (except for the Mk.150 and 152 engines in theCC2/CC2QF aircraft) is their EHP figures so for the purpose of the exercise I treated EHP as ESHP which I think gives me a slightly higher maximum_torque than it should be, but substantially less on the Viscounts and more on the 748s than you are using.
Regards
David