R22 Increased MAUW - Feasible?
Thread Starter
R22 Increased MAUW - Feasible?
Having spent a reasonable bit of time instructing in the R22 Beta II over the past little while, I'm often annoyed at the significant restriction in fuel load with a couple of hefty, or even partway hefty, POB.
The B206 was previously restricted to 1450 kg but 1519 on the hook, then Bell presumably re-did the sums based on public demand and said go ahead and fly it to 1519 internally loaded (with appropriate restrictions).
Question for those with more time and knowledge about the Robbie - what's the basis of the max weight limit in the R22, and what are the odds of getting it increased so we can get more than 1.1 hrs safe endurance with a couple of fat bastards up front?
Forward C of G and boost limits spring to mind, but does anyone know for sure what the limiting factor is?
The B206 was previously restricted to 1450 kg but 1519 on the hook, then Bell presumably re-did the sums based on public demand and said go ahead and fly it to 1519 internally loaded (with appropriate restrictions).
Question for those with more time and knowledge about the Robbie - what's the basis of the max weight limit in the R22, and what are the odds of getting it increased so we can get more than 1.1 hrs safe endurance with a couple of fat bastards up front?
Forward C of G and boost limits spring to mind, but does anyone know for sure what the limiting factor is?
does anyone know for sure what the limiting factor is?
Lose some weight, Army! Might not have mattered in a 9 Sqn Hubert, but when you have to hang your arm out the window to be able to get enough aft cyclic, it is time to either find skinny students, or get in a bigger bus.
Maybe I'm not answering your questions specifically, but you're talking about a 635 kg MTOW aircraft... how much more do you realistically expect can be done? The R22 doesn't have the best safety record to begin with.
If you need more range/endurance, you won't ever get what you're wanting done in the until the pilots go on a diet or you pony up for the G2 (280 kg useful load) or the R44.
If you need more range/endurance, you won't ever get what you're wanting done in the until the pilots go on a diet or you pony up for the G2 (280 kg useful load) or the R44.
My guess would be main gearbox life limitations, and safety margins on blade stalling issues, with high pitch angles required for the extra lift, throughout the flight envelope?? But that is a guess.
Thread Starter
All fair comments, but I'm talking about some kind of a specific dispensation or reassessment of limitations to allow something like an increase to, say, 635 kg (extra half hour flying time) with the restriction that you are operating to and from ground effect (eg departing an airfield or similar), possibly airspeed restrictions until you're under 622 kg, and whatever else was deemed necessary.
If you hover taxi over a flat surface for a short period, do an airfield departure, then use restricted power / speed until a bit of extra weight burns off and go on your merry way, then it doesn't seem unreasonable to me that that would be as kind or kinder to the aircraft than lots of things that get done to them in the course of normal training.
16 litres extra fuel would put the C of G further back for that initial stage, which would be a good thing, and without knowing where the actual limitation lies it's hard to say what would or wouldn't be possible as far as extending the envelope a la the Bell situation.
If you hover taxi over a flat surface for a short period, do an airfield departure, then use restricted power / speed until a bit of extra weight burns off and go on your merry way, then it doesn't seem unreasonable to me that that would be as kind or kinder to the aircraft than lots of things that get done to them in the course of normal training.
16 litres extra fuel would put the C of G further back for that initial stage, which would be a good thing, and without knowing where the actual limitation lies it's hard to say what would or wouldn't be possible as far as extending the envelope a la the Bell situation.
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Do Robinson think there is enough margin in the design for this?
If so, does this mean a recertification of the aircraft, and who's going to pay for that?
As I recall, the limiting factor for most Beta 2s that I flew was forward C of G, hard to get away from just not being able to get the cyclic back any further...
If things are that limited, might be time to look at a different bus.
If so, does this mean a recertification of the aircraft, and who's going to pay for that?
As I recall, the limiting factor for most Beta 2s that I flew was forward C of G, hard to get away from just not being able to get the cyclic back any further...
If things are that limited, might be time to look at a different bus.
Thread Starter
Yes, many people can of course lose weight, but if you get someone who's just a big person but still makes it under the seat limit, with an 85 kg instructor, not unreasonable, you're at max all up and on the forward c of g limit. Putting extra fuel in moves the c of g back approximately in line with the sloping upper forward envelope boundary, so there wouldn't be a great change in where you sit regarding cyclic position.
All I'm suggesting is if it could happen with the Jet Ranger in (I assume) response to public demand, there might be some tweaking and pencil sharpening the Robinson engineers could do if it's not going to create an undue hazard.
Maybe, but the 206 was around a fair few years before they upped the max weight internally loaded.
Cough...splutter...what!? 
All I'm suggesting is if it could happen with the Jet Ranger in (I assume) response to public demand, there might be some tweaking and pencil sharpening the Robinson engineers could do if it's not going to create an undue hazard.
im pretty sure that if they could they would.
Can't they drink less beer
You quoted the 206 having 2 weight limits, one for AUM if the skids have to support it, and a higher limit if the extra load was on the hook.
The engine and transmission could always cope with the upper weight, but the skids and crashworthiness after a touchdown auto could only cope with 1450. So, if anything went wrong while above 1450, the pilot had to pickle the load to get below 1450 for the landing.
After many years, Bell strengthened the landing gear to allow 1519 all the time - but the restrictions to speed in the CG envelope still applied.
The R22 rotor RPM decays so fast that I wouldn't want to be flopping around with a higher-than-normal pitch setting, and the judgment required for a heavier touchdown is considerable.
The engine and transmission could always cope with the upper weight, but the skids and crashworthiness after a touchdown auto could only cope with 1450. So, if anything went wrong while above 1450, the pilot had to pickle the load to get below 1450 for the landing.
After many years, Bell strengthened the landing gear to allow 1519 all the time - but the restrictions to speed in the CG envelope still applied.
The R22 rotor RPM decays so fast that I wouldn't want to be flopping around with a higher-than-normal pitch setting, and the judgment required for a heavier touchdown is considerable.
Thread Starter
Fair points again, it could be the rate of decay of Nr I suppose, although if you're talking risk management in the type of operation I'm suggesting, a nav from an airfield, then I don't reckon it would have you in a significantly worse position than normal for more than a short time.
Ok what i said could be misconstrued, the R22 is a great aircraft if you fly within the prescribed envelope, outside it you are dicing with death. That goes for almost all aircraft but the safety margins for the R22 are carefully calculated. don't mess with them full stop...
In an R22 when the blades stall you lose lift instantniously far faster than you can do anything to stop, not worth playing with.
In an R22 when the blades stall you lose lift instantniously far faster than you can do anything to stop, not worth playing with.
Last edited by Redland; 19th Jul 2014 at 02:40.
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Comparing the B206 to an R22 is just not on. For the R22 to carry more it would need to be redesigned with a head and blades that had a lot more inertia which would require a stronger gearbox and what you would actually have is a different helicopter altogether.
Frank built a machine very close to it's limits and as has been seen time and again it is a tricky little thing to fly.
The blades and head on a B206 are massive when compared to the light weight and fairly insubstantial design of the R22 blades (which constantly have issues).
I think as has been pointed out several times with the current AUW you only have about 1.5 s to drop the pole I think with increased weight and making no design changes this would reduce even further with even more R22s hitting the ground than do currently.
Frank built a machine very close to it's limits and as has been seen time and again it is a tricky little thing to fly.
The blades and head on a B206 are massive when compared to the light weight and fairly insubstantial design of the R22 blades (which constantly have issues).
I think as has been pointed out several times with the current AUW you only have about 1.5 s to drop the pole I think with increased weight and making no design changes this would reduce even further with even more R22s hitting the ground than do currently.
Without knowing the exact certification standards, I'm going to make a wild guess here and say that the R22 would have some trouble passing certification if it were to be developed today.
The autorotation characteristics and the lack of reserves when it comes to engine-off landings are bad enough at 1370lbs, and whoever had to establish and verify that H/V diagram must have had balls of considerable size. Increasing the weight would make it worse. No way that would be allowed, unless a bunch of other parts are changed as well, and as others have said - once you start going down that road, you'll soon have to change the whole helicopter.
Out of all the machines I have flown, I would say the R22 is the LEAST suitable for a MGW increase. I have around 2,000hrs on type btw.
The autorotation characteristics and the lack of reserves when it comes to engine-off landings are bad enough at 1370lbs, and whoever had to establish and verify that H/V diagram must have had balls of considerable size. Increasing the weight would make it worse. No way that would be allowed, unless a bunch of other parts are changed as well, and as others have said - once you start going down that road, you'll soon have to change the whole helicopter.
Out of all the machines I have flown, I would say the R22 is the LEAST suitable for a MGW increase. I have around 2,000hrs on type btw.
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Remember, the R22 originally had a 1300lb limit and was pushed up to 1370lb for the Beta without, as far as I know, any structural change. When asked the question many years ago, Frank said it would mean beefing up some of the structure to maintain fatigue criteria, which would mean stronger drive train to support the extra weight and so on. Law of diminishing returns and why Robinsons would prefer people to use R44's, which also have a greater profit margins I suspect.
Think you will find this is to do with autos was told by md in a 500's case that it autod like a brick at 3550 lbs.where as at 3000 lbs it was fine. So hence like a jetbanger can lift more but only if on hook