R22 cooling fan
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R22 cooling fan
Anybody know how much power that fan consumes from the engine? in% or hp`s at 2652 eng rpm?
I guess you have to subtract that number from the claimed 124 cont hp`s.
Thanks
I guess you have to subtract that number from the claimed 124 cont hp`s.
Thanks
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Its a longish time since I was flying R22s and I seem to remember the Fi told me the fan needed about about 18% to do its job, but the previous guys were right, you have what you have and if it aint enough then dump fuel or diet,.... then you may unstick or fly into higher areas.
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Thanks for replies, but I disagree..
Just do a comparison with the schweizer, that uses a 180hp lycoming 360. This engines has 180hp in an airplane as well. So that tells me you have to SUBTRACT the power needed to drive the fan, and auxillaries.. Theen finally you get the power delivered to the drive system.
Soo in comparison to the robinson we have to subtract the fan consumption from the claimed derated 124 hp to get the shaftpower to the rotorsystem.
18% sounds very reasonable. which means about 25hp is consumed by the fan.
Thanks for inputs guys
Just do a comparison with the schweizer, that uses a 180hp lycoming 360. This engines has 180hp in an airplane as well. So that tells me you have to SUBTRACT the power needed to drive the fan, and auxillaries.. Theen finally you get the power delivered to the drive system.
Soo in comparison to the robinson we have to subtract the fan consumption from the claimed derated 124 hp to get the shaftpower to the rotorsystem.
18% sounds very reasonable. which means about 25hp is consumed by the fan.
Thanks for inputs guys
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Yes, I know.
Questions:
Is there 124hp to drive the transmission?
Or do we subtract the power needed to drive the fan from the claimed 124hp?
Thanks for comments
Questions:
Is there 124hp to drive the transmission?
Or do we subtract the power needed to drive the fan from the claimed 124hp?
Thanks for comments
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Hi Lars
sounds like you have a bit of appreciation to go.
Don't worry about the power drains except for, around the bar-talk.
The belts, xmon, T/R system, fan, magnetos and everything else in the engine accessory gearbox all have friction loss and power requirements. Why even including disc angles and the excess power required by that all add up to whole heaps of sleepless nights if that is what turns you on.
The horsepower is produced at the top end of the cylinders, (that's the bits just under the spark plugs) and everything else costs.
The POH conveniently sets out the H.P required and or allowed to fly the A/C with an easy indentikit method of selecting it. It's by reference to the one round BIG dial right in front of your mark one eyebal, called a manifopld pressure guage. There is another simple correction to help you use it which is on the chart right above your scone with temparature conversions etc.
Frank recommends that you select a maximum of 124 HP cos I guess he has figured out how much you need to safely overcome gravity and have the engine and other bits not get all choked up with heat and emotion.
You may even find that all rotary recips use proportionally the same cooling power, which is set to keep the damm thing cool at max continuous power.
The only thing other that you need do is make sure that at flat pitch and 104% the engine does not use excessive power.
I know what that is for me.
For your own good you should find an engineer to tell you what it is for you in your climate, and if that is ok, then go.
The rest is Bollocks.
Now I know where english beauracracy came from. one of your forebares in a long boat.
sounds like you have a bit of appreciation to go.
Don't worry about the power drains except for, around the bar-talk.
The belts, xmon, T/R system, fan, magnetos and everything else in the engine accessory gearbox all have friction loss and power requirements. Why even including disc angles and the excess power required by that all add up to whole heaps of sleepless nights if that is what turns you on.
The horsepower is produced at the top end of the cylinders, (that's the bits just under the spark plugs) and everything else costs.
The POH conveniently sets out the H.P required and or allowed to fly the A/C with an easy indentikit method of selecting it. It's by reference to the one round BIG dial right in front of your mark one eyebal, called a manifopld pressure guage. There is another simple correction to help you use it which is on the chart right above your scone with temparature conversions etc.
Frank recommends that you select a maximum of 124 HP cos I guess he has figured out how much you need to safely overcome gravity and have the engine and other bits not get all choked up with heat and emotion.
You may even find that all rotary recips use proportionally the same cooling power, which is set to keep the damm thing cool at max continuous power.
The only thing other that you need do is make sure that at flat pitch and 104% the engine does not use excessive power.
I know what that is for me.
For your own good you should find an engineer to tell you what it is for you in your climate, and if that is ok, then go.
The rest is Bollocks.
Now I know where english beauracracy came from. one of your forebares in a long boat.
yep, why would you substract anything - the derating limit is for the transmission, and the derating chart tells us at what MAP we reach that limit. Obviously the people who made that chart knew that there was a fan and belts between engine and transmission, so i would think they considered this when making the chart. They did the substracting for us (probably by simply measuring power at the transmission driveshaft instead of the crankshaft)
Also, 18% or 25hp or 19 kilowatts for the cooling fan? That would be one hell of a fan! 18% sounds more like what the T/R uses.
Also, 18% or 25hp or 19 kilowatts for the cooling fan? That would be one hell of a fan! 18% sounds more like what the T/R uses.
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Thanks for contributing guys!
You did not answer my very simple question, but told a lot of other already known things..
I have a good idea of how it all works mechanically. The waste heat produced by a petrol piston engine (especially with stone age tech) is MASSIVE compared to how little mechanical power you get out. That requires a powerconsuming fan.
Typeertification requirement is adequate cooling for 5? minutes at worst condition. max alt, max temp, max gross, max pwr. + of course manufacturer safetymargin.
I don`t have an actual problem/case with a copter, just askin out of pure curiousity, if someone knows the number, cuz I can imagine that fan sucks big hp`s for non lift purposes
You did not answer my very simple question, but told a lot of other already known things..
I have a good idea of how it all works mechanically. The waste heat produced by a petrol piston engine (especially with stone age tech) is MASSIVE compared to how little mechanical power you get out. That requires a powerconsuming fan.
Typeertification requirement is adequate cooling for 5? minutes at worst condition. max alt, max temp, max gross, max pwr. + of course manufacturer safetymargin.
I don`t have an actual problem/case with a copter, just askin out of pure curiousity, if someone knows the number, cuz I can imagine that fan sucks big hp`s for non lift purposes
Lars1 - the problem is that you would have to subtract every element of the drive train to reveal the amount of HP that is actually devoted to getting the helo into the air.
It is generally known as Rotor Profile Power and includes the power required for all the engine and gearbox ancillaries, the TR drive shaft, GB, hub and blades and the power required to drive the MR at flat pitch on the ground.
The remaining HP is then either Induced Power (that used to induce a flow through the rotors) or Parasite Power (that required to overcome parasite drag). The first is high in the hover and low in forward flight, the second is exactly the opposite.
The 124 HP (power available) is spread across these 3 areas with Rotor Profile Power being nearly constant across the speed range and the other 2 varying with speed.
It is generally known as Rotor Profile Power and includes the power required for all the engine and gearbox ancillaries, the TR drive shaft, GB, hub and blades and the power required to drive the MR at flat pitch on the ground.
The remaining HP is then either Induced Power (that used to induce a flow through the rotors) or Parasite Power (that required to overcome parasite drag). The first is high in the hover and low in forward flight, the second is exactly the opposite.
The 124 HP (power available) is spread across these 3 areas with Rotor Profile Power being nearly constant across the speed range and the other 2 varying with speed.
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Lars, 25BHP sounds about right. This is one of the reasons modern reciprocating engines opt for water cooling, along with better temperature control. This is just one of the parasitic losses that engine designers have to put up with. It will have already been included in the brake dynamometer testing that Lycoming will have done for Robinson...
Still if you could demonstrate a failsafe reliable electric system which did not affect certification, and improved fuel burn, i'm sure Uncle Frank and Mr. Lycoming might raise an eyebrow...
Still if you could demonstrate a failsafe reliable electric system which did not affect certification, and improved fuel burn, i'm sure Uncle Frank and Mr. Lycoming might raise an eyebrow...
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Thanks, very good explaination about the different types of drag and their change with relative airspeed, but it was a little outside the box in relation to the question. Maybe I explained myself a little unclearly.
The initial question was:
How many % power is delivered via the drivebelt at full allowable throttle?
How many % power is delivered to the fan at full allowable throttle?
Of the total power (124hp)
Because we are operating with a fixed rpm, the power required (fixed centrifugal fan blades in enclosed shroud, hence fixed angle of attack) to drive the coolingfan is fixed (for a certain DA) regardless of collective position.
If any of you don`t know the answer, that`s fine cuz this is a robinson specific question, I should maybe asked Frank about.
Have a nice weekend
The initial question was:
How many % power is delivered via the drivebelt at full allowable throttle?
How many % power is delivered to the fan at full allowable throttle?
Of the total power (124hp)
Because we are operating with a fixed rpm, the power required (fixed centrifugal fan blades in enclosed shroud, hence fixed angle of attack) to drive the coolingfan is fixed (for a certain DA) regardless of collective position.
If any of you don`t know the answer, that`s fine cuz this is a robinson specific question, I should maybe asked Frank about.
Have a nice weekend
ok, again...
You assume that the 124HP are measured at the crankshaft, and that what reaches the transmission is actually less than than, because of fan and belts. And you want to know how big that difference is.
on the other hand, I assume that the engine is actually producing more than 124HP at the crankshaft, say 140 or so, but only 124HP reach the transmission, the difference is what is used by fan and belts.
This would make sense, since the derating limit is determined by the transmission and the engine is well capable of producing more than 124HP.
so, questions:
- does anyone know where the 124HP are measured - crankshaft, crankshaft with fan, or after the drive belts?
- why do you want to know how much the fan uses?
You assume that the 124HP are measured at the crankshaft, and that what reaches the transmission is actually less than than, because of fan and belts. And you want to know how big that difference is.
on the other hand, I assume that the engine is actually producing more than 124HP at the crankshaft, say 140 or so, but only 124HP reach the transmission, the difference is what is used by fan and belts.
This would make sense, since the derating limit is determined by the transmission and the engine is well capable of producing more than 124HP.
so, questions:
- does anyone know where the 124HP are measured - crankshaft, crankshaft with fan, or after the drive belts?
- why do you want to know how much the fan uses?
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I`m just askin of pure curiousity. Been a&p for 8 yrs @ chc and like to know the mechanical features.
So Graviman:
-The Schweizer 300cb(i) has a n/a 360ci which produces 180hp at 2700rpm and max manifold press.
-Lycoming rate that n/a engine at 180hp either if it is for airplane or copter.
-Do you think schweizer has overtuned this engine above lycoming claimed hp limit in order to compensate for the fan, and distribute 180hp to the belts?
-If no, why would frank claim his hp without fanpower consumption?
Yes, the carburated stoneage engine produce alot of heat energy that needs to be rejected. That demands much of power
I have a good answer, that i belive in, to my question now
So Graviman:
-The Schweizer 300cb(i) has a n/a 360ci which produces 180hp at 2700rpm and max manifold press.
-Lycoming rate that n/a engine at 180hp either if it is for airplane or copter.
-Do you think schweizer has overtuned this engine above lycoming claimed hp limit in order to compensate for the fan, and distribute 180hp to the belts?
-If no, why would frank claim his hp without fanpower consumption?
Yes, the carburated stoneage engine produce alot of heat energy that needs to be rejected. That demands much of power
I have a good answer, that i belive in, to my question now
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lars1
I have never had anything to do with the R-22 but understand the 124HP is main transmission limit. A way to work out how much power the fan pulls out of the engine is to get hold of the Lycoming Operators Manual for the particular model engine fitted. In there you will find a graph giving the RPM, MAP and HP of the base engine (no cooling fans, generators, vacuum pumps etc). Look that up with Robinsons 124HP figures and you should find the Lycoming chart will give you a higher figure. The difference will be the cooling fan HP + generator + any other ancillaries the engine is driving. Good luck and hope I'm clear enough.
I have never had anything to do with the R-22 but understand the 124HP is main transmission limit. A way to work out how much power the fan pulls out of the engine is to get hold of the Lycoming Operators Manual for the particular model engine fitted. In there you will find a graph giving the RPM, MAP and HP of the base engine (no cooling fans, generators, vacuum pumps etc). Look that up with Robinsons 124HP figures and you should find the Lycoming chart will give you a higher figure. The difference will be the cooling fan HP + generator + any other ancillaries the engine is driving. Good luck and hope I'm clear enough.
