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HeliTorque :: View topic - The R22 as a training helicopter
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HeliTorque Forum Index » Torque, Chat, and Chill!

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WhirlyGuy
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PostPosted: Wed Mar 18, 2009 11:52 am    Post subject: Reply with quote

Heliwhore wrote:
Heres a suggestion for a training helicopter, I will admit this is not my own original work.

R44, strip out the back seats and any trim to lighten it as far as possible. De-rate the engine further (after all, it's only a 2 seater), to extend service intervals and extend component life, allowing cheaper per-hour running costs.

Reduce fuel burn as part of the de-rate, once again lowering per-hour.

We now have a two seat trainer with the running costs not that much higher than a 22, but with high inertia rotor, none of the weight/CofG problems, better climb rate and top end speed, meaning less time travelling/climbing so training objectives met faster. Greater luggage space. The list goes on....


Sounds clever but I reckon if you start taking anything out of the helicopter such as the seats or what not then you facet the problem that the helicopter would probably have to be re-certified in that configuration I would guess?

Also if ever the school wanted to put back everything they have taken out in order to do that then it's going to take a bit of time to do and as we all know, time is money so may not be all that effective.

I know where you're coming from though.

WhirlyGuy
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Pogue
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PostPosted: Wed Mar 18, 2009 3:10 pm    Post subject: Reply with quote

Heliwhore wrote:


Reduce fuel burn as part of the de-rate, once again lowering per-hour.

How does that work? With two people you don't even get close to your MCP in an R44 as is, you would have to re-engine it. I think the Raven I is as close to that concept as we're going to see in an R44.
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MikeBill
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PostPosted: Wed Mar 18, 2009 4:48 pm    Post subject: R22 as training helicopter Reply with quote

The R22 has the advantage of being mechanically very reliable. The derated engine avoids all the problems associated with high engine rpm (3000rpm) and underpowered performance and consequent unreliability of other piston types, such as unannounced engine failure, overpitching etc. Any R22 mechanical defect usually manifests itself in terms of noises, vibration, high oil consumption many hours before becoming catastrophic and the aircraft can be fixed.

Manage the carb heat properly, manage your fuel, dont fly if the clutch/belt take-up time is outside limits, avoid negative g, dont fly in conditions outside your capability or in IMC.

If faced with a sudden catastrophic engine failure this will be accompanied by dramatic yaw to the left. Lets look at our priorities. The first is to get the lever down quick and establish our autorotation. Second pick a nearby field where you can end up into wind. Third make sure you you in fact get there by using the advance techniques you were taught. Only if we get these right do we need the bit at the bottom.

As regards Engine Off Landings, if they are practised to a power on recovery, whereby you achieve a level 4 to 5kt hover taxi by 4 feet skid height, then the profile you are achieving is identical to a EOL. If the flare is conducted progressively then all the vertical speed will be killed and all the excess forward speed before you need to take any lever. If the pilot can do this, then the only difference is in the EOL the aircraft will continue to sink to the ground and you will need the other pedal to keep straight. The skill is in not taking the lever until the last possible moment, making sure you are level and not tail low (otherwise you will bounce), and looking at least 50 or more metres ahead during the flare and thereafter to keep straight. Your peripheral vision will work out the height for you. Once you touch down freeze the stick position and the lever and concentrate on your feet.

Think about it practically. An EOL for real will be into an unprepared field, not level, not smooth. Unless you are very lucky the aircraft will be damaged, but the aim is to keep you undamaged. Pity the fixed wing driver who in the same circumstances would be touching down at 50 to 70 kts. Nobody expects him to avoid damage to the aircraft. If you the instructor or your student can do the power on recovery as described above consistently, then the damage to the aircraft is unlikely to be any greater than that occurring to the skilled instructor who can grease them on because he will still have to cope with the same slopes, ruts and potholes at the bitter end.

Hope this puts the whole thing in better perspective.
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chopperjockey
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PostPosted: Wed Mar 18, 2009 5:26 pm    Post subject: Reply with quote

Quote:
If faced with a sudden catastrophic engine failure this will be accompanied by dramatic yaw to the left. Lets look at our priorities. The first is to get the lever down quick and establish our autorotation.


What is the max cruise speed of the R22? About 95kts?
What is the autorotation speed of the R22? About 65kts?

I may be wrong but if you lower the lever quickly at 95kts would you risk going into neg g and removing the tail boom in the process?

Would it be safer to flare the speed off back to 65kts and then lower the lever to avoid this? Confused
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PostPosted: Wed Mar 18, 2009 5:45 pm    Post subject: Reply with quote

MikeBill
Please explain how an R22 cant be overpitched ?????????or is that a bad interpretation of your post ?
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MikeBill
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PostPosted: Wed Mar 18, 2009 5:47 pm    Post subject: Reply with quote

"What is the max cruise speed of the R22? About 95kts?
What is the autorotation speed of the R22? About 65kts?

I may be wrong but if you lower the lever quickly at 95kts would you risk going into neg g and removing the tail boom in the process?

Would it be safer to flare the speed off back to 65kts and then lower the lever to avoid this? Confused"

R22 normal cruise 80-85kts. Lowering lever will not put you into negative g, it may feel like you are dropping but it is less positive g that's all. Let the nose drop and you will get negative g.

It is normal to flare the aircraft if it is necessary to recover from low rpm (usually the case if engine failure unexpected).

Hope this helps
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veeany
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PostPosted: Wed Mar 18, 2009 6:04 pm    Post subject: Reply with quote

Mike

Thank you for bothering to respond, everything you say is correct and does bring some balance to this.

It is very difficult to be able to prove statistically that the R22 is any worse a trainer, as due to its success there are so many of them around that its difficult to compare in a fair manner how people used to crash their helicopters and how we do it nowadays. We can't compare just numbers of accidents as there are far more 22s than say 300s so the comparison would not work. We can't really scale the figures based upon how many there are on the register as that makes no allowance for the number of hours flown. The number of hours flown figures which are bandied around are just not accurate enough, I've seen how they are produced and suffice to say that I don't expect this to change in the next few years as no one is really collecting what is necessary at the moment.

There have always been dual and solo instruction accidents, and I guess there will always be, what I would like to do is reduce those through education and training.

I know quite a few instructors who are not interested in the slightest in knowing how their aircraft work, and equally quite a few who are.

The R22 in the hands of someone who knows what they are doing is a decent enough machine, I am just very bothered by inexperienced instructors teaching on them (I can offer no solution, just a statement), we seem to lose too many for the same reasons every year and those reasons are Carb Ice, Practice engine offs and mishandling. That does not mean the experienced guy cannot make a mistake, indeed the figure from EHSAT seem to point towards <100hrs experience either total or on type being the big blips on the experience radar from an accident point of view in any type.

I know one instructor who has had an R22 accident of his creating, who is still not interested in learning anymore.

Iam putting together what I think are the deadliest sins in the R22 with some supporting evidence, I will do the other types as I go and perhaps the type specfic (not Robinson specific) view will become a focus for future safety evenings, with input from people on here and elsewhere we might end up with something that is true.

I don't want any bias to be in it, but I don't think that any dressing up of quirks should be allowed, it should be just said as it is, that is what is really important (perhaps thats the northerner in me !)

Anyone going to answer my question about wind limits and the AD, even by PM ?
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MikeBill
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PostPosted: Wed Mar 18, 2009 6:09 pm    Post subject: Reply with quote

"Please explain how an R22 cant be overpitched ?????????or is that a bad interpretation of your post ?"

What I meant is the R22 is less likely to become overpitched than other piston helicopters.

In a Hiller, Bell 47 Hughes, Enstrom etc at high auw you can reach max available MAP lifting into the hover or completing an approach to the hover, and thereafter any further application of lever will result in falling rpm.

In the R22 in a similar situation it is less catastrophic as the max MAP is a gearbox or aerodynamic limit. In the hover or at the end of the approach in a R22 extra lever beyond placard MAP will not lead to loss of RPM unless your misapplication of lever is extreme, as there is a couple more inches available at the density altitudes we operate at. This wont do the gearbox or other mechanicals any good, and must be reported, but may prevent an accident.

In other helicopter types you can overpitch lifting to or coming to the hover from an approach. The aircraft will start to sink, the pilot will apply more lever, more overpitch will occur. The aircraft will also start to yaw as tail roror rpm and hence tail rotor thrust is lost.

Full throttle height for the R22 is about 5 to 6000 feet density altitude at which point this advantage has completely disappeared.
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PostPosted: Wed Mar 18, 2009 7:05 pm    Post subject: Reply with quote

Quote:
Sounds clever but I reckon if you start taking anything out of the helicopter such as the seats or what not then you facet the problem that the helicopter would probably have to be re-certified in that configuration I would guess?


This is an idea that was being thrown around the school by one of the instructors. He was actually meaning this to be a Robinson "sold as" training vehicle, with everything unnecessary pulled out to make it cheaper/lighter. Before the wise cracks come, yeah, that wouldn't be much on a Robby.
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PostPosted: Wed Mar 18, 2009 10:15 pm    Post subject: Reply with quote

If you removed weight to below the minimum flying weight, what then? screw off some pitch on the main blades?
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PostPosted: Thu Mar 19, 2009 8:19 am    Post subject: Reply with quote

Mikeball
Hm when I did my instructor course more than 10 years ago i had to go in the R22 . May have been a beta or even an hp cant remember but to get it to hover with 2 up and 15 gals of fuel we had to pull max mp so it was really easy to overpitch / overboost ( overboost is exceeding mp limits, I know it is not the best terminology ) the rrpm would certainly droop which is a sign of overpitching or governor not responding quicker enough when having to pull the power in on most landings, never got the buzzer going though !!!!!!! but instructor said it was " normal " practisce to get to max mp and sometimes more, he used the derated argument to justify !!!
I think it is dangerouus to say that R22's cant be overpitched as there are a lot of very novice pilots on this forum who will take that as gospel.
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PostPosted: Thu Mar 19, 2009 8:42 am    Post subject: Reply with quote

There were quite a few experienced pilots who wound their necks in when Robinson issued the blade AD that said if you have been continually operating over Max MAP then scrap your blades !

My words used above until I can find the now old AD I refer to.

I was demonstrated the 29" MAP Hover by a very nice FIE (not Mike Bill another one), he was one of them.
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PostPosted: Thu Mar 19, 2009 9:12 am    Post subject: Reply with quote

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the rrpm would certainly droop which is a sign of overpitching or governor not responding quicker enough when having to pull the power in on most landings, never got the buzzer going though !!!!!!! but instructor said it was " normal " practisce to get to max mp and sometimes more, he used the derated argument to justify !!!


What !!!!! now thats some irresponsible instructing. Lets teach people straight out of the box that its fine to overload an aircraft and fly outwith limits. Eye Slam
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PostPosted: Thu Mar 19, 2009 9:23 am    Post subject: Ignoring MAP liits on R22s Reply with quote

Heliwhore

It was rife when I learnt to fly, I hope its changed now, but I guess some people still give the MAP limits a good ignoring.

GS
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PostPosted: Thu Mar 19, 2009 9:33 am    Post subject: Reply with quote

It just another example tht makes me appreciate the instruction that I recieved all those years ago. I try to pass on the standards that were passed to me.

I know it still goes on to some degree. We sometimes use one machine in particular that the owner/instructor regularly flys outwith limits. It's the only machine that I have to flatly refuse to fly, gonna fall out of the sky one day.
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