3top said: Hmmm. I think Newton might have been thinking slightly differently.

What you interpret as low "G" when you rapidly lower collective is in fact only that the helicopter starts down before you do. Lowering the collective won't cause the helicopter to experience any significant low "g". In the R22 the blades do not go into negative pitch with a full-down collective, so the airframe will continue to pull down on the disk. More importantly, if the helicopter is accellerating downward rapidly enough to make you feel light in the seat, the airflow is also more rapidly reversing. This is one significant difference between dropping the collective and a cyclic pushover. Believe me, the faster you get the collective down, the less Nr decay you will have.

Next, the rate at which Nr decays is directly related to the amount of blade pitch being pulled just before the power goes away. This is only somewhat related to airspeed - if you are in a 500'/min rate of descent at 70kt, Nr will decay much less. But I'm splitting hairs on this one.

However, the rate that an object FALLS is not affected by its horizontal velocity. A bullet shot from a gun over a level surface will hit the ground at the same time as another bullet dropped simultaniously from the same height (aerodynamic effects aside). Inertia is relative to velocity, but velocity is a vector quantity, so in the vertical plane, a helicopter at 70kt has no more inertia than a helicopter at 0kt.

Lu.

Thanks for getting your usual fast response from Heliport. :D

If you could do one more small favor, would you please thank Heliport for me and tell him that stupid me had not been clicking on 'Show results as posts'. :uhoh:

Dave

the coyote writes:
"And yes, I'm as concerned as you are that someone might take this speculation on board somehow and in confusion deviate from what they have been trained to do when the blood is pumping.

Stick to the training! Pprune is a great source of info, ideas, and increased awareness. How people choose to interpret that and what course of action they ultimately take is up to them eh?"

I agree. I hope that what I've put forward is simply accepted as my theory of what's going on, not to be tested by someone in no reasonable position to do so safely. The RFM and manufacturer's instruction should be trusted. Unless there is an unforseen problem (jammed/misrigged controls) the collective should simply be lowered and NR allowed to slowly come back up. It's just my nature to look at the other 'what if's', and consider what's actually going on physically. Perhaps this isn't the place to do it. But if not here, where?

Flingwing207 says:
"This is one significant difference between dropping the collective and a cyclic pushover. Believe me, the faster you get the collective down, the less Nr decay you will have."

To a point...
I think it's been said before that dumping the collective too quickly will actually slow the NR more than a less hasty reduction. Consider that when in regular lifting flight air comes down through the rotor disk at a decent clip. If you instantly reduce collective to zero and at portions of the blade the blade angle becomes negative, the air coming down on the blade will cause a quite substantial drag with negative lift (negative angle of attack). Why would you want more drag and negative lift (possible zero-g)? By more gradually reducing collective the blades don't end up pushing up at the air. You allow the airflow through the disk to change direction as the blades do, perhaps maintaining a small constant angle of attack or simply zero angle of attack, rather than a large negative one.

You also say, "In the R22 the blades do not go into negative pitch with a full-down collective, so the airframe will continue to pull down on the disk."
If this were true than what would cause the rotor to keep turning in an auto despite the drag acting along the span? The type specific info in the back of "Helicopter Performance, Stability, and Control" by Prouty states that the collective range on the R-22 is +1.5 to +14.5deg. This is likely the root angle. The twist is -7deg, which means that at less than 21% span the local blade angle is positive, but beyond that it's negative (-5.5deg at the tip).

Gaseous says:
"Cyclic input alters the plane of rotation. NOT the angle of attack. (Bailey, principles of flight, p40)."
and
"forget the red herring of cyclic affecting pitch. do not confuse pitch with angle of attack. forward cyclic will not increase angle of attack on retreating blade"

I think you are over generalizing Bailey's statement. Think of what happens when you're in a hover and push forward cyclic to commence forward flight. Sure, your forward cyclic will cause the plane of rotation to tilt forward, but how? If the angle of attack doesn't change then the lift in that quadrant is unchanged and the disk won't respond.

Also consider fast forward flight. You know that the blade has a larger angle of attack on the retreating side than the advancing side because the relative airspeed acting on the blade is different. To yield the same lift on each side the higher relative airspeed on the one side (advancing) is offset by the higher angle of attack (and higher blade angle) on the other. This is due to your forward cyclic input. If the angle of attack was the same on each side the lower lift due to the slower relative airspeed on the retreating side would cause the disk to tilt back and you'd slow down. If you brought the cyclic back to center, the blade angle and also the angle of attack on the retreating side would similarly be reduced and the disk would come down over the tail as a result. The steady state final condition would put you back in a hover.

What I think he meant was simply that the average blade angle as the blade revolves does not change, and thus the average angle of attack does not change.

Going back to my earlier calculation... You are right in your statement that blade angle does not equal angle of attack. However, they are strongly related, especially when we discuss transients. In my earlier post I made the point that I was making broad assumptions and this was one, but I stand by my earlier position that for illustrative purposes and especially for maneuvering, this is fair. It looks like my non-standard text didn't come across correctly. I'll fix that.

The change in angle of attack is exactly equal to the change in blade angle for a moment before the airflow has a chance to respond. As time goes by the angle of attack finds a new equilibrium, but for a short while their changes are the same.

Evening all, Sorry if this intellectual chess is boring some of you. Perhaps Heliport would put this all in a new thread which you could avoid.

Krylian, you said,

Quote: I think you are over generalizing Bailey's statement. Think of what happens when you're in a hover and push forward cyclic to commence forward flight. Sure, your forward cyclic will cause the plane of rotation to tilt forward, but how? If the angle of attack doesn't change then the lift in that quadrant is unchanged and the disk won't respond.

I don't have access to books at present so someone will correct me if I'm wrong.

Don't forget flapping to equality.

i.e. If cyclic pitch is applied the blade will flap to maintain the angle of attack.

If cyclic pitch is increased the blade will flap up, reducing pitch. It is the flapping that alters the plane of rotation. There is a lag due to the inertia of the blade in the vertical plane but this is small. so in practical terms the angle of attack does not change much unless you make rapid cyclic movements. All flapping in one direction occurs within 1/2 revolution. I seem to remember reading in an NTSB document that stall develops over several revolutions.

I had a discussion with another pilot today and this came up.

Why is aft cyclic good at high RRPM but bad at low?

The answer is this. At high Nr aft cyclic increases the angle of attack, moving the autorotative region outward along the blade and increasing its efficiency. This decreases the area and drag of the end, driven section. Lovely, RRPM goes up just like we were told it would. The inboard stalled section of the blade is small and irrelevant.

As Nr falls, more of the inner section of the blade stalls, so drag here becomes relevant, but no matter, aft cyclic increases the AOA, the autorotative bit is still up to the job. As it moves out along the blade it still reduces the drag of the end bit of the blade and overpowers the extra drag of the stalled section. RRPM goes up. Still OK

Nr falls more The stalled section at the root is now big and its drag is in equilibrium with the autorotative force. The drag at the end of the blade is small in comparison. Recovery may be possible if you dont muck it up. Any increase in angle of attack will push the stalled region outward so that the drag overpowers the autorotative force. RRPM goes down and the rotor stalls. Aft cyclic doesnt look so good here. I am guessing we are in the low 70s% area, but don't really know.

Aft cyclic is great at high RRPM but you can have too much of a good thing at low RRPM.

If you dont want to call it forward cyclic you could always call it less aft cyclic.

I believe that there must be some warning of impending stall, probably left roll and pitch down. At this point you are not far off doomed as stated in R22 SN24 (which I read today, comparison to fixed wing not so ridiculous eh, snoop?). I suggest you all read SN24 before making your mind up what action if any is worth taking at this point in your life.

I do not suggest you do anything other than you were trained to do.

Why?
Low intertia.
Solution
Keep practising.

EDIT

SOME POSTS HAVE BEEN DELETED BEFORE THIS ONE WHICH MAKES THIS AND SOME OF THE FOLLOWING IRRELEVANT

Buy an R44, stop playing with autos and fly over good landing areas as much as possible, always fly at a good height so if or when you might be that unlucky 1 in a million that has an engine failure you have plenty of time to sort yourself out. If the horn aint screaming you raise the collective a little more. Your probably staring at the RRPM guage too much, attitude, wait assess, and in between that look for a nice flat spot. And remember if you turn a lot you have to work harder to control RRPM. Also read thread about R22s maybe coming to an end. I dont proclaim to be any good at it myself but in training there is a big emphasis on keeping the needles in the green but thats mainly to keep their aircraft in good nick, you will be glad of all that inertia in the blades at the bottom. Ive been will instructors in BiAnnuals who still balls it up after thousands of them.

Concentrate your efforts on to other things that will keep you alive longer like good planning and downwind ops, hot and heavy in that R22.

:D

maaaate.......if you have to even ask that question, it speaks volumes to the quality of the basic training you received, and worse still to the quality of the training you received on the R22. For God's sake don't dick around with practice autos on your own until you at least get much more experience than you presently have, and even then, don't do them unless you have an experienced instructor with you.
In the meantime, go find an experienced R22 Instructor and get that life saving autorotation training you seem to have been denied to date..Take care & safe flying!

The key is indeed in maintaining a consistant pitch attitude with the cyclic. If you are sawing the cyclic back and forth to maintain airspeed (common if you spend too much time looking inside at the airspeed indicator), you will have a very difficult time holding RRPM steady.

Try this - go up to 2,000' (or higher) AGL, 65 KT and just start smoothly lowering the collective while keeping your eyes outside and maintaining a 65 kt attitude. DON'T LOOK INSIDE until a few seconds after you have gotten the collective all the way down. Then take a very quick glance at the airspeed and RPM, then eyes back outside. Smoothly make whatever attitude adjustment you deem necessary, then HOLD THE CYCLIC STILL.

At the same time you are doing this, listen to the RPM. If it starts rising, raise the collective about 5mm. Wait, listen, if it holds steady, leave the collective alone. If the RPM starts going down, lower the collective 1/2 the distance you raised it.

Now here's the trick: every time you are going to move the cyclic aft or make a turn, nudge the collective up 5mm just before you make the cyclic movement. If you are moving the cyclic forward or rolling out of a turn, lower the collective first. The more you plan to go aft cyclic or turn, the more collective you raise in anticipation. Same for lowering collective.

As long as you anticipate the RPM changes caused by flaring and disk loading, autoing the R22 is not difficult!

Hope this helps - John

Flingwing207 has it right on. The problem with wandering rpm in autorotation is almost always that changes in the inflow of the rotor are making the rpm climb or drop. The cyclic can be as powerful as the collecive.

The way to make the rpm stay solid is to keep the pitch attitude of the aircraft steady, which keeps the disk at the same relative angle of attack. As Fling says, keeping the cyclic steady, which keeps the nose steady, is the key.

One thing to feel while you descend is the vertical G, which tells you exactly what the rpm is going to do. If you pull the nose up, to build a little load factor, and also increase the inflow. The inflow makes the rpm rise, and the loadfactor is your clue. After some practice, you can judge the collective up that is needed by feeling the load factor, so a slight increase in load factor calls for a slight increase in collective, and vice-versa. This load factor sense is also helpful in turns, as the load factor is what makes the rpm rise in turns. My experience is that most students are ok at triming up on collective on turn entry, but they plumb forget to lower the lever when they roll out of the turn.

I agree with oldrotorhead as well.

It seems like you don't have a handle on it, let alone any confidence.

I suggest a change of attitude from "groan..." and $hitting yourself to being a bit more positive and practical:

"OK, I haven't got a handle on this yet, and I've just got to do as many as it takes until I do."

More training man, do as many as you have to. Everyone had a problem with autos at some stage.

How long. . .?
 

When I was doing my PPL (R22) one of my instructors taught told me to transition away and climb into the circuit. . Climbing through 200ft agl (23" 60kts) and just crossing the airfield boundary he said to me, 'have you got your headset volume correctly adjusted?'. So I reached up with my left hand to find the volume control on my headset. . .

Then this is what happened - He chopped the throttle and said (quickly) "Right, the engine has just failed what are you going to do about it?" I said, (slowly) "Errr. . . " and watched the RRPM fall to 80%

He said, "Too late" dropped the lever and threw it into a near 90deg banked turn and got back inside the airfield boundary. RRPM now about 90% with about 50ft to go. . another 90deg banked turn in the opposite direction to level us and the RRPM was up to 100% just in time for him to raise the lever and cushion the landing.

Going over this in my mind with a stopwatch it must have been about 4 seconds between 'engine failure' and the lever going down.

I guess it's not always 'who you know. . .'?

:cool:

R22 production line to close
 

R22 production line to close.
This came to me from outside of aviation and they seemed serious about this. I can't believe it but a reason was given which sounded plausable - product liability costs.
No timing was given so could be out and out speculation.

Robinson’s 2004 Sales Soar Past 2003
 

Dontcha just love a Rumour Network?

Are you sure about the closedown ?

There has been speculation about this all year...

there was a article in flight international in the last week or so, in which frank said they were in no hurry to build a bigger helicopter, but had long term plans for a 5 place helicopter but hadnt even chosen a powerplant yet, he didnt like the expense/fuel consumption of a C20, and had even thought about a diesel, but didnt like the weight.

he didnt say anything about stopping the R22 though.

regards

CF

I interviewed Frank Robinson a year ago for a couple of UK magazines. The headline on the subsequent articles was "End of the line for the R22?"
Frank said he was considering stopping production of the R22 for several reasons. The model had been overdeveloped - it started out as 108 hp and now it's 180 hp with the same drive train, it's been blown out to 1370 lbs and you can't do any more with it. He'd already stopped making the Mariner and the instrument trainer, and his company's primary focus was on the R44, for which he was fighting off customers.
Furthermore, he believed the R44 Raven II would make the best trainer ever. Two up, it has massive reserves of power, it handles benignly and, he said, it would make the safest trainer ever built. It would be cheaper than a piston Enstrom, and cheaper than a Schweizer 269 with similar equipment.
Add to this the fact that the margins are greater on the larger machine, and that even with his new factory extension he's fighting hard to get the waiting list for the 44 down, while planning relatively big margin developments, and you can see his point.

Robinson R22 Corner
 

hi backender

try doing a search for r22 blades & you'll get plenty of hits

of particular interest might be this fairly recent one: here

http://www.pprune.org/forums/showthr...ght=r22+blades

i'm not aware of any definitive study on the topic , but surely someone here would have some good directions, particularly the anti-Rxx crowd who seem to be able to come up with all the technical data ;)

R22
 

Have just joined the forums - interesting stuff.

Have a dekko here to see the busted R22 blades:

http://brumbyhelicopters.com.au/auspage1.htm

R22 alt/battery failure
 

If that alternator light comes on and stays on...

how long till the battery loses its charge?

I know that the POH says:
"continued flight with malfunctioning chargning system can result in loss of power to electronic tachometers..."

but is that all you'll lose if the battery quits?

how about:
-governor
-radio
-transponder
-gps
-landing lights
-nav lights
-strobe

thanks for any input
:ok:

J

Yes, you would loose all the other things aswell. But you can fly without those.

Imagine trying to fly with Govenor, Horn, and both tachs out.

I would say pretty impossible.

cl12pv2s

cl12pv2s,

do you know how long the battery would last with no charge from the alternator?

J

As always it depends on the load, If you find an answer it will always be approx.

As Aser says, it really depends. If I was at night, I would want some battery for the landing light when I get down, and panel lights maybe. If I was in 'Class B' I might choose to keep the transponder on. If I was in low vis, then maybe the strobe would stay on.

Radio Transmit draws a lot. So does the landing light. The other equipment draws little. The situation would dictate how you use your remaining supply.

As the POH says 'Land as soon as practical', I would think there would be enough for about 10-15 miles of flight. But that is a COMPLETE guess.

Maybe a techie can answer this.

cl12pv2s

The R44 has between 30 and 45 mins of battery life after the red ALT light illuminates. The POH is 'land as soon as practicable' so you do not need to dive into the nearest field. In most of the UK, this will mean an urgent divert to the nearest airfield, with a stop watch running to ensure you keep WELL WITHIN the timings.

If this is not possible then locate a suitable secure landing site)next to big house, etc) as an engineer will appear at some point within 24hrs with a new or replacement alternator.

(I've had this problem - it was a loose alternator pillar. The red light winked on and off for a while then stayed on. Divert ensued. This could be a bigger issue over water or in remote areas. Make the radio call as soon as it happens).

For the R22 the figures are "similiar". I did once take a R22 in for maintenance with the alternator out as the second pilot on board. The J/T was 25 mins.

In all cases, minimise electrical usage. Take out the second radio/ GPS/ lights if not dark/ etc to keep amp usage down and watch the Ammeter.

For this point try the Robinson Safety Course. It can be done but care needed to avoid overspeed (and stall). Engine sound is the clue but better not to be in the situation.

A robbo battery new will last for roughly 40-50mins I think...

I presume that you are guessing that this is all after ALT failure? I have only once had a problem with ALT's and that was when I had a belt snap during flight, flew 20mins back to base with the following off:

Radio and Transponder
Nav/Strobe and Landing Lights
Gyros

If you ever get an ALT failure just load shed as much as you can!

HH :cool:

For those of you that dont know the tach's run of the mags as well as the alt and battery, dont believe me swith them both of in flight.

Batteries in UK must have a yearly then 6 month capacity check if on public transport. Therefore answer will be in flight manual !

Further ".. Continued flight without functioning alternator can result in loss of electronic tach, producing a hazardous flight condition"

So, land as soon as practical

Does the Robbie really fly on Double As??

I was once told by an instructor that while bringing back a 22, the alt light came on. However the flight time was still around an hour. He flew the hour back with no problems but recommended not doing it again.
Robinson does not say how long his battery's will last, but as a few of you pointed out ' land as soon as pratical' is the wisest option.

The Tachs will still work as long as the clutch is engaged and there is life in the battery due to the tachs running off a seperate circuit. :ok:

In the UK some Robbo manuals have a supplement in them with an approximation of BAT life upon ALT failure. Seen a HeliAir supp in one of our Robbo POH's re BAT life.

HH :cool:

CRAZYBROADSWORD,

I don't believe that the tachs run off the mags. The governor makes adjustments in RRPM using shaft rpm (completely separate system from the tachs). I could be wrong, but there are small magnets built in that allow the governor to calculate RRPM on it's own (simple - but effective). IntheTin is correct in the fact that the tachs are on a different circuit for safety. For example, if you have an ALT failure + GOV failure... you are still good to go (but tachs won't last long on battery alone). What will happen if you lose your tachs and nothing else in a normal situation?... absolutely nothing. The governor will compensate for you and you can land safely without low RRPM or overspeeds. The need to expedite a landing is predicated on need power for other items (lights, radio, transponder, power for an emergency in-flight restart, etc).

I hope I can clear up some confusion particularly in relation to the Tachs and where they get their power from.

CrazyBS is right in that both tachs will continue to read with both the battery and the alternator off. It is wrong, though, to infer from this that the tachs are being POWERED by the magnetos. They are not.

Both tachs require power to work. They also need an input that tells them the speed. (The sensing inputs are 1. a hall effect magnetic sensor on the forward yoke of the forward flex coupling in the case of the rotor tach and 2. a connection to the right magneto in the case of the engine tach. To confuse us pilots further the right tach is on the left side of the helicopter. This is because the engine is mounted back to front compared with the way it is generally used in fixed wing applications.)

The power to the tachs with the alternator and battery master both off comes from a "tach bypass circuit". This is a direct link from the battery to the tachometer bus. So-- switch the alternator off and then switch the battery off and you'll still have power to the tachs. You WILL lose the governor and the Low RRPM warning horn.

This is handy if you've got an electrical fire in flight when you need to stop electrical power getting to the panel but need the tachs to get down.

To prevent the battery from going flat while the aircraft is sat in the hangar the tach bypass circuit runs through the clutch switch. With the clutch switch in the "disengaged" position the bypass circuit is switched off (isn't Mr Robinson clever?). A diode in the circuit prevents electrical current travelling from the Tach Bus back to the main bus.

So with your "electrical fire in flight" scenario, you switch off the Alternator and Master Batt but keep the tachs. Only if you were then to put the clutch switch to "disengage" (or pull the tach breakers) would you lose the tachs. (But you wouldn't want to do that would you)

All this is academic if you've lost the alternator and you've flattened the battery! Hence the warnings in the POH about jump starting a machine with a dead battery. If you jump start it and then go flying before the battery has charged you are one failure away from not having a clue about your RRPM. (Unless you've got perfect pitch to judge the engine note).

Back to the original question posed by jibboo. The battery is a 25 ampere hour battery. This THEORETICALLY means that it will supply 25 amps for an hour (or 5 amps for 5 hours...or 1 amp for 25 hours...etc). In reality the voltage will be plummetting long before that time is reached. It does give you some idea of the effect of using each bit of kit on battery duration. Have a look at the rating of each breaker for a rough idea of how much current each item consumes.

Hope this helps

cheers!:ok:
J

Blade placard R22
 

So we all know not to pull down on the blade during preflight,
What exactly gets bent/broken if you were to pull down on it?

the static stop?
J.

R22 operating costs
 

Some of you may think I'm a little mad. But - I decided I wanted to get my instructor rating in the UK having never flown anything other than a toy glider.

I have operated several businesses before and after doing a bit of research concluded that the best and cheapest way to achieve my goal was to buy an R22.

This done, I am now in possession of a lovely R22 beta II with low hours.

To subsidise the thing I am being offered a leaseback by my school. Now being new to this game I have calculated my costs per hour and what it will cost to pay for the 22, but the problem is I come up short on what my school is offering me per hour and what it actually costs in my estimation to run the machine per hour.

What I would like to know is the actual cost per hour to run it, from the people who really know and operate R22's, and not from my novice calculations.

Any help would be appreciated. Thanks.

I forgot to add I'm in the UK.

I have been in a very similar position to you, I bought a refurbished R22 and used it to complete my PPL and at the same time leased it back to the school who taught me to fly.

The REAL cost per hour is impossible to calculate in advance. The organisation who sold me the R22 told me one figure, the school who leased the machine estimated another and my own calculations gave a different amount.

I believed that by leasing the helicopter to the school they would burn lots of hours and therefore bring the insurance cost per hour down.
Insurance £7K per year / 350 hrs = £20.00 per hour as apposed to my 80hrs private use per year at £87.50 per hour. What I did not realise is that the maintenance bills would be so big. When using the machine for training it really got a hammering, all those hovering auto's, auto's to the ground, run on landings, new student's trying to pull 30" MP and hours of hovering at max power. Within six months of owning my R22 I had a 6.5K maintenance bill for unscheduled work.

I lost money on every hour the machine flew, I sold the machine to the school that leased it and got an R44, and I lease this machine to the same flying school and have had much more success. Most people who fly the 44 already have there PPL and either do there type rating on it or self fly hire. The hours are much lower per year but I have had no unscheduled maintenance in nearly two years.

Hope this helps

PM me if you want to know more figures.

ive not had a r22 but have owned others and leased them to flying schools [one in yorkshire with a flying school that did not pay ,falsified hours,and badly treated the helicopter ect,]

what i would say is before picking the school ask a few questions
some below

how many aircraft has the school damaged latley

ask the other owners who lease their helicopters to the school do they get paid on time ,do the hours match up to the students flying times,

find out who also has leased helicopters to this school in the past and ask them if they have had problems

ask if they have they had any serious accidents and is there a trend to them

is the school run by competent people ,have they proper comercial licences /instructor ratings ect.

please dont get bitten like i did there are lots of proffesional outfits out there that do a good job .and only a few bad ones ,

most dont flout the laws but some do .

i dont think its fair to name names but my one was at a airfield with no competitors hes managed to stab all of them in the back already

nuff said