CH 47 Chinook Power curve differences from Single rotor.
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CH 47 Chinook Power curve differences from Single rotor.
Good morning all,
I'm getting examined next week by my trappers and wondered if anyone on PPRUNE had any information/ references on the differences for a tandem rotor power required curve from that of a single rotor helicopter.
Specifically i'm interested in the effect of:
-interference effects on induced power in the hover.
-LCT function on parasite power
-the lack of a tail rotor on rotor profile power.
Thanks in advance
WW
I'm getting examined next week by my trappers and wondered if anyone on PPRUNE had any information/ references on the differences for a tandem rotor power required curve from that of a single rotor helicopter.
Specifically i'm interested in the effect of:
-interference effects on induced power in the hover.
-LCT function on parasite power
-the lack of a tail rotor on rotor profile power.
Thanks in advance
WW
Join Date: Dec 2001
Location: Philadelphia PA
Age: 73
Posts: 1,835
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You can confuse them by asking them if they know of the effects of sideslip on the low speed power required - evidently the Canadian CH-46 SAR model had a sideslip indication for single engine fly-away to get better performance.
As for the other stuff - very complex, and I'm surprised that anyone would be asking those sort of questions. My answers would be:
interference effects on induced power - there may be some interference effects on power required overall, but you would have a difficult time to separate induced power from the total power
LCT and parasite power - how do you separate this out? - the LCTs might (and even that is a bit of a stretch) effect things slightly at extremes of CG, but you as the pilot have no real control over them. Parasite power, (at least in my books) is for things like transmission losses, hydraulic pumps - how does this relate to LCT?
Tandem rotor and profile power - a bit of a red herring (unless my understanding is way off) - the lack of a tail rotor only means that all the power can go to vertical thrust. Profile power is the power to just turn the rotors, so while a tail rotor may take less power to turn than a main rotor, it's not really contributing to lifting stuff...
Just my two cents worth.
As for the other stuff - very complex, and I'm surprised that anyone would be asking those sort of questions. My answers would be:
interference effects on induced power - there may be some interference effects on power required overall, but you would have a difficult time to separate induced power from the total power
LCT and parasite power - how do you separate this out? - the LCTs might (and even that is a bit of a stretch) effect things slightly at extremes of CG, but you as the pilot have no real control over them. Parasite power, (at least in my books) is for things like transmission losses, hydraulic pumps - how does this relate to LCT?
Tandem rotor and profile power - a bit of a red herring (unless my understanding is way off) - the lack of a tail rotor only means that all the power can go to vertical thrust. Profile power is the power to just turn the rotors, so while a tail rotor may take less power to turn than a main rotor, it's not really contributing to lifting stuff...
Just my two cents worth.
One can be too Curious it would appear....unless you can control it from the cockpit....and one is not writing a Thesis on Rotorcraft Power Dynamics....why in the Hell would anyone be asking questions such as those posed?
I would have to respond by asking exactly what does it matter....as all that is accounted for in the Aircraft Performance Charts provided in the RFM....and suggest the quiz move on to that topic.
Yes...the Tandem Rotor does work better with an application of side slip just prior to ETL when very power limited. The Aft Rotor works better in clean air which can be achieved by an application of pedal....swing the advancing side of the Aft Rotor into the existing Relative Wind.
I would have to respond by asking exactly what does it matter....as all that is accounted for in the Aircraft Performance Charts provided in the RFM....and suggest the quiz move on to that topic.
Yes...the Tandem Rotor does work better with an application of side slip just prior to ETL when very power limited. The Aft Rotor works better in clean air which can be achieved by an application of pedal....swing the advancing side of the Aft Rotor into the existing Relative Wind.
