R22 Corner
Better red than ...
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Ranges from:-
50hr £280 - £600 (plus consumables/ parts)
100hr £360 - £800 (as above)
Annual £1400 - £2000 (as above)
Plus VAT and any unexpecteds
50hr £280 - £600 (plus consumables/ parts)
100hr £360 - £800 (as above)
Annual £1400 - £2000 (as above)
Plus VAT and any unexpecteds
Join Date: Feb 2003
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Robinson rotor head question.
Chiplight. What conditions exist at the point where the blades are directly fore/aft. Surely at this point in their rotation they lose the effect of incoming foreward airloads and for a split second are only suject to the torque? Bug.
Iconoclast
Join Date: Sep 2000
Location: The home of Dudley Dooright-Where the lead dog is the only one that gets a change of scenery.
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Lead lag and rotor tilt.
To: chiplight
As I previously stated the blades are offset in front of the mast relative to the pitch change axis. This is done to minimize inplane bending of the blade. The purpose of this offset is to try to align the blade pitch axis (CG) with the center of pressure. Or, is it the aerodynamic center (I forgot which). Since this is the case it would be difficult to draw a straight line through the teeter hinge and align with the blade CG.
Because of the underslinging of the rotorhead there is minimal if no lead and lag when the pilot introduces cyclic pitch. The blades will maintain the same degree of cone relative to each other and the cone angle will remain the same as when the pilot first introduced collective pitch. When the blades flap about the cone hinge it will deviate from the original cone angle and with this change in position the blades will lead and lag. On a conventional flex rotor with offset hinges or on the more modern helicopters with elastomeric bearings when the pilot introduces cyclic pitch the blades will lead and lag in direct proportion to the degree of cyclic pitch input by the pilot.
As I previously stated the blades are offset in front of the mast relative to the pitch change axis. This is done to minimize inplane bending of the blade. The purpose of this offset is to try to align the blade pitch axis (CG) with the center of pressure. Or, is it the aerodynamic center (I forgot which). Since this is the case it would be difficult to draw a straight line through the teeter hinge and align with the blade CG.
Because of the underslinging of the rotorhead there is minimal if no lead and lag when the pilot introduces cyclic pitch. The blades will maintain the same degree of cone relative to each other and the cone angle will remain the same as when the pilot first introduced collective pitch. When the blades flap about the cone hinge it will deviate from the original cone angle and with this change in position the blades will lead and lag. On a conventional flex rotor with offset hinges or on the more modern helicopters with elastomeric bearings when the pilot introduces cyclic pitch the blades will lead and lag in direct proportion to the degree of cyclic pitch input by the pilot.
Join Date: Mar 2002
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What does a 50 hourly service entail?
I haven't heard of a 50 hourly service (apart from change the oil and do inspections of frame and blades - which are pilot allowed actions). Does the CAA in Britain mandate further services?
I haven't heard of a 50 hourly service (apart from change the oil and do inspections of frame and blades - which are pilot allowed actions). Does the CAA in Britain mandate further services?
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bug,
In a teetering rotor, the torque isn't much different when the blades are fore and aft than when they are at the adv/retreating position.
Why? because the advancing blade sees higher velocity air which WOULD increase lift and drag, but flapping equalizes lift (I should say moment) between the blades by reducing AoA on the adv blade and increasing AoA on the ret blade. When lift is equalized, so is drag, since most of the drag is induced drag, which comes from lift.
Lu,
the aerodynamic center of lift is often 25% back from the leading edge, so thats where the cg of the blade is located to avoid flutter and other probs. That's why the feathering axis is not in the center of the blade. Since each blade is facing the opposite way, the line bewteen the cgs of the blades will cross through the center of the mast, ideally at the teeterbolt. Ther coned rotor can tilt any way it likes with cyclic and the cg of the cone will stay near the teeter bolt if the undersling is correct.
In a teetering rotor, the torque isn't much different when the blades are fore and aft than when they are at the adv/retreating position.
Why? because the advancing blade sees higher velocity air which WOULD increase lift and drag, but flapping equalizes lift (I should say moment) between the blades by reducing AoA on the adv blade and increasing AoA on the ret blade. When lift is equalized, so is drag, since most of the drag is induced drag, which comes from lift.
Lu,
the aerodynamic center of lift is often 25% back from the leading edge, so thats where the cg of the blade is located to avoid flutter and other probs. That's why the feathering axis is not in the center of the blade. Since each blade is facing the opposite way, the line bewteen the cgs of the blades will cross through the center of the mast, ideally at the teeterbolt. Ther coned rotor can tilt any way it likes with cyclic and the cg of the cone will stay near the teeter bolt if the undersling is correct.
Last edited by Chiplight; 21st Apr 2005 at 02:29.
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Robborider
Unlike Australia, some Foreign Civil Aviation Authorities request that all maintenance including oil changes are only performed by LAME, hence the cost of a 50 hourly.
It makes life interesting when you have a breakdown somewhere in the Jungle....Thanks God for Aussie training
Unlike Australia, some Foreign Civil Aviation Authorities request that all maintenance including oil changes are only performed by LAME, hence the cost of a 50 hourly.
It makes life interesting when you have a breakdown somewhere in the Jungle....Thanks God for Aussie training
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R22 Performance Graphs
Hi all,
I'm confused (as always!) about a certain aspect of the R22B IGE/OGE Hover ceiling vs gross weight charts. My instructor tells me thet the temperature lines on this chart are ISA lines. The way I read it, there is only one ISA line on these charts and that is the 'standard day' line. The rest are OAT lines.
If you were to use them as ISA lines your'e calculations would be incorrect ...... wouldn't it?
I'm confused (as always!) about a certain aspect of the R22B IGE/OGE Hover ceiling vs gross weight charts. My instructor tells me thet the temperature lines on this chart are ISA lines. The way I read it, there is only one ISA line on these charts and that is the 'standard day' line. The rest are OAT lines.
If you were to use them as ISA lines your'e calculations would be incorrect ...... wouldn't it?
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Hi,
looking at the R22 charts in the POH which is on my desk, my interpretation is that there are two types of temperature lines on each chart.
There is a dashed line and there are unbroken lines.
The dashed line indicates a standard day temperature. This is what your instructor is probably talking about. During certification a lot of the performance calculations are referenced to a "standard day" set of conditions. They then workout from there what effects temperature has on the performance. Infact if you have a look at the introduction to section 5 of the POH it states:
The unbroken lines are temperature lines. The higher temperature lines are closer to the bottom of the chart, which follows from higher temperature = less performance for the same weight.
If your instructor still has problems with this then I suggest that he goes back to school for a while until he understands what the charts actually state.
Tinkicker....
looking at the R22 charts in the POH which is on my desk, my interpretation is that there are two types of temperature lines on each chart.
There is a dashed line and there are unbroken lines.
The dashed line indicates a standard day temperature. This is what your instructor is probably talking about. During certification a lot of the performance calculations are referenced to a "standard day" set of conditions. They then workout from there what effects temperature has on the performance. Infact if you have a look at the introduction to section 5 of the POH it states:
The performance data presented in this section was obtained under ideal conditions. Performance under other conditions may be substantially less. Hover performance data was obtained with carburettor heat off.
The unbroken lines are temperature lines. The higher temperature lines are closer to the bottom of the chart, which follows from higher temperature = less performance for the same weight.
If your instructor still has problems with this then I suggest that he goes back to school for a while until he understands what the charts actually state.
Tinkicker....
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Thanks TK
I believe my instructor is definately refering to the solid lines as ISA lines! It was explained to me that if, for example, it was 20 degrees C at SL, it would be an ISA +5 day. You would therefore follow the up from your max weight, say 1300lbs to +5 (solid line) and follow accross to read your max hover ceiling - appx 6300ft PA in this example (OGE). I get appx 6000ft using the method I thought was correct prior to that conversation. Not a huge difference I guess but still ........
I believe my instructor is definately refering to the solid lines as ISA lines! It was explained to me that if, for example, it was 20 degrees C at SL, it would be an ISA +5 day. You would therefore follow the up from your max weight, say 1300lbs to +5 (solid line) and follow accross to read your max hover ceiling - appx 6300ft PA in this example (OGE). I get appx 6000ft using the method I thought was correct prior to that conversation. Not a huge difference I guess but still ........
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R22 Servicing Costs
Quichemech.
Ever herd of Anonymity! Isn't this what Pprune is all about?
I want to know because I'm interested.
No offence intended but you don't need to know where I'm based.
Musket097.
Ever herd of Anonymity! Isn't this what Pprune is all about?
I want to know because I'm interested.
No offence intended but you don't need to know where I'm based.
Musket097.
Senis Semper Fidelis
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Hey Musket,
You are right of course, if you want to remain anon then I feel we will all respect your wish!
But Come on GUY get real, the Uk has 63,000,000.5 people living in some 6500 towns and villages plus some 30 + counties and Metro areas,, so why the pricky reply !
Normally being anon could mean several things,:-
You are a member of the IRA
" " " Al-Qeada
" " " Royalty
Or you could be a Whistle Blower, or some other murky type
We all have some sense of being able to help each other, on this particular Rotorheads Forum, and help is available in truckloads, but I am afraid snappy answers more often than not will get you a great big ZERO, Kapisch!
Have a nice day somewhere
Peter R-B From Lancashire
Hiding behind Vfrpilotpb!!
You are right of course, if you want to remain anon then I feel we will all respect your wish!
But Come on GUY get real, the Uk has 63,000,000.5 people living in some 6500 towns and villages plus some 30 + counties and Metro areas,, so why the pricky reply !
Normally being anon could mean several things,:-
You are a member of the IRA
" " " Al-Qeada
" " " Royalty
Or you could be a Whistle Blower, or some other murky type
We all have some sense of being able to help each other, on this particular Rotorheads Forum, and help is available in truckloads, but I am afraid snappy answers more often than not will get you a great big ZERO, Kapisch!
Have a nice day somewhere
Peter R-B From Lancashire
Hiding behind Vfrpilotpb!!
The Original Whirly
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Almost whenever I meet anyone in the aviation world and mention I'm a helicopter instructor from North Wales - and they can see I'm female - they go, "Oh, you're Whirlybird". And much as I enjoy the instant fame, sometimes it would be rather nice to be an anonymous one of 63,000,000.5 people again. Of course, I could remove some details from my profile...but it's probably too late now - everyone knows me. 
So, Musket097, I for one quite understand.
So, Musket097, I for one quite understand.
Sneetch - just because it is 20 degrees C at sea level (ie an ISA + 5 day), doesn't mean it is an ISA + 5 day at 6000'. That is why the temperature lines are there so you can enter at a pressure altitude and an OAT at the height you want to hover at and see if you can do it at the AUM you will be at.
An ISA day assumes a lapse rate of temperature with height of 1.98 degrees C per 1000 ft - in the real world the lapse rate can be much more or less than this and can reverse if there is an inversion.
If you know it is + 8 degrees C at 6000 PA (ie an ISA +5 day then you can use the ISA + 5 line on the graph, you cannot assume that the lapse rate from SL to 6000 is as per ISA.
An ISA day assumes a lapse rate of temperature with height of 1.98 degrees C per 1000 ft - in the real world the lapse rate can be much more or less than this and can reverse if there is an inversion.
If you know it is + 8 degrees C at 6000 PA (ie an ISA +5 day then you can use the ISA + 5 line on the graph, you cannot assume that the lapse rate from SL to 6000 is as per ISA.
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Vfrpilotpb
I didn't think Musket097 was being snappy or pricky (whatever that means) and has every right to query why someone should want to know where they are based or why they are asking.
And as for your comment, and I quote you directly," Normally being anon could mean several things:- you are a member of Al Qeada/IRA/Royalty" beggars belief. Whatever you're taking I suggest you don't fly for the duration.
Get a life and don't be so ridiculous.
Ewe Turn
I didn't think Musket097 was being snappy or pricky (whatever that means) and has every right to query why someone should want to know where they are based or why they are asking.
And as for your comment, and I quote you directly," Normally being anon could mean several things:- you are a member of Al Qeada/IRA/Royalty" beggars belief. Whatever you're taking I suggest you don't fly for the duration.
Get a life and don't be so ridiculous.
Ewe Turn
Passion Flying Hobby Science Sponsor Work
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Chiplight
As you state the opposite blades evenout most of the lift/drag differences which are for individual blades quite different at different positions.
This is also graphically shown in the drag curves I published in other posts.
Delta3
This is also graphically shown in the drag curves I published in other posts.
Delta3
Better red than ...
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Normally being anon could mean several things,:-
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Part of the fun of Pprune is guessing who is who. Some are not as anon as they think, Eh Ed.
If you post often enough your anonymity becomes compromised.
Mind you, I do have a second, really anonymous persona for those most controversial posts.
If you post often enough your anonymity becomes compromised.
Mind you, I do have a second, really anonymous persona for those most controversial posts.