Sorry to whinge at the previous participant but:
The rotor does not turn the "wrong way", merely the other way ( much more ergonomic if you ask me)
The space in the cab is excellent, you can shove all sorts of bits and pieces left and right and most of it doesn't fall out of the ddor when you open it (ie 206)
The throttle is fine where it is, never had a problem with it at all!
The tank, well at least it's big enough to get you somewhere without having to re-fuel every two hours.
NO I am not French, but US helicopters are certainly NOT gods gift to us pilots.

PS anyone else had Nr, Ng and TOT needles all wobble(fluctuate) at the same time in a 206? Bloody strange if you ask me

All interesting theory but...........
 

2 things are happening -

1/ The cyclic induced PIO. Friction up the cyclic as per instructions in the Llama RFM to the point where it is quite difficult to move. You'll get used to it. The controls are obviously fixed to the frame and if the mast/transmission start to oscillate it subsequently moves the controls more. The better the balance of the MR the better the hover as well. Don't stir the pot. With friction on you'll soon tire of trying to.

I have had a 355 hover for 45 seconds or more without touching the cyclic. This is with .02 IPS.

2/ The wake from the MR OGE misses the tail rotor due to contraction and when IGE moves across the tail rotor and causes translation lift in the TR but not consistently. This causes a yaw roll couple and gets worse the closer you are to the ground. This can be proved by hovering in a tail wind. Keep it straight with your feet. The wake around the cabin is minimal.

The strake on the B2 was to create a Coanda effect to help the tail rotor by destroying lift on the right side. I doubt there is much Coanda effect without it as per B, D. Interesting the B3 doesn't have it.

The tank sloshing is limited to earlier unbaffled tanks and will NOT be noticed in the hover unless your a stick stirrer, only in the cruise at about 60-70%.

Try it. Works for me, steady as a rock.

Ok, two cents from me as well:ok:

I once had the pleasure to talk to one of the designers of the AS 350, and one of my questions was of cource why it is so unstable. Should not have said unstable:E I got an instant reply "It is not unstable, it is precise". I guess it could be argued. Anyway he said they (Eurocopter) where not really sure why exactly is was a bit twitchy (he agreed on that), a lot of contributing factors he said, no magic item.

He also said when they installed the long tailpipe on the exhaust on the B3 it became much better, and this was a surprice to them.

I have had the pleasure to fly many diffrent versions (all but the D) and in my opinion there are some diffrences.

Low skids are worce then high( I know it was argued the other way, but this is my opinion).

Short T/R output drive worce then long (standard now).

Twinstar blade with trailing edge tab much better than without.

B3 exhaust also much better.

Best contributing factor - lots of houres on the machine and to have it recent. Look on a high time 350 pilot not flying anything else - steady as a rock, but do not put that guy in a steady dampend platform, such as the S76, he will make it look bad by overcompensating:E

Cyclicrick,

I totally disagree with you that the throttle is OK where it is. I guess you havent had too many emergency's that require throttle manipultion.

High side gov failure in an Astar is a little differnt, you must immeaidtly lower collecitve and take the FCL out of the govering range.


Stuck pedals, kinda hard to adjust throttle to help control yaw.

There are several other things i wouldnt mind having it on the collective for.

They shouldnt have waited for the B3 to do it , but put it on the B2 years ago.

RB

....so then why DOESN'T the EC120 wiggle ?

That you can put down like a feather... not enough coriander ?

THE REASON THE SQUIRELL WOBBLES WHEN IT LANDS IS THE RESULTING FORCE CAUSED BY THE MAIN ROTOR HEAD AND THE POSITION OF THE TAIL ROTOR BEING AT DIFFERENT HEIGHTS
THIS RESULTANT FORCE CAUSES THE HELICOPTER TO "HANG" RIGHT SKID LOW .
THIS COUPLED WITH THE "STINGER" {FITTED TO ALLEVIATE GROUND RESONANCE} CAUSES THE HELICOPTER TO INITIALLY LAND ON THE RIGHT REAR STINGER TIP WHICH IN TURN CAUSES A PIVOTING/ BOUNCING MOTION-USUALLY OVERCORRECTED BY MOST PILOTS I AGREE THAT THE BEST WAY TO LAND IS A GENTLE RUN ON LANDING

as355f1 you sound more qualified to comment than me as I ve never flown the squirrel and guess I m not likely to in the near future :( but...

Are there any helicopters where the main rotor head is at the same level as the tail rotor?

In my limited experience all helicopters tend to hover with one skid low - or is that just my flying?

I always thought the stringer wa the part which stopped me dinging the tail rotor - what is it on the squirrel?

And surely one of the bonuses of helicopters is you don't need to 'run on' during 'normal ops'?

PW

PS - got a headache so please don't shout! :)

pilotwolf, i believe the stingers that 355f1 refers to are actually the small "beavertails" installed at the aft end of each skid tube, those are for ground resonance attenuation. remove those and things can get interesting. also there are tolerances for the tails and they need to be replaced if the angle / clearance is out of limits
dr

I don't recall a major problem with a 355, I always found a BO105 much more sporting, especially when landing on a trolley!!
Maybye it was just my gash 'hands on'??

"Run-on landings" on a mountain log pad or when placing your heels on a log to keep from sinking!!?? - In my opinion, not a good way to get around the handling characteristics - if you are never going to land anywhere other than an airport, well you may be able to get away with it, but if you fly utility, and the times you have to be precise, you won't have the practice or technique down to do a good job.

Follow the advice on frictioning up of the cyclic (although lots of smooth Astar pilots use no friction), and not stirring the pot (actually hardly even moving the cyclic), staying in trim and keeping a steady approach right to the ground, and not hovering before landing, will help you master the beast. If every landing is a no hover landing, with your descent controlled by collective and not by moving the cylcic, you will be on your way to perfecting the landing.

Y'all, I've done 30k+ landings in this airframe, in calm to 50 knots, level ground to elevated (all varieties), and my observations-

1) Yes, it ordinarily lands right side skid heels first. If you put that down without translation and not descending too quickly, you won't know when it touches. Translate a little over the ground except forward and all bets are off. If I "feel" for that first touch, I always mess it up. Yes, the control trim positions change suddenly, but nothing unacceptable. If you have a stabilised and slow descent going, it'll be a quick small movement or two and the collective will be on the bottom.
So- eyes out front, hold it in place, and slow uniform descent until the collective stops going down. Just like any helicopter.

2) The aircraft will land fine, as above, unless winds anywhere but on the nose- Then it darts and jumps a bit more, especiialy sporty with 10-15 knots on the right rear quarter! If you're up to form, you can still do the "Technique 1)" but it's not easy. Don't feel for the ground!!!
10-15 knots at the right rear quarter can get real interesting, especially on an elevated pad with turbulence. Those conditions can bounce the automatic leveling device, a/k/a tail skid. It'll pitch up suddenly, commence a descent, and yaw suddenly.
A bunch of wind improves things (and stabilises the airflow, which I think supports my tail rotor wash theory), and it does better in all quads, as long wind steady state. Plenty tail rotor authority and few surprises.

3) If all else fails, a little forward as the right rear skid heel touches. Good when you absolutely gotta plant this pig as it's pointing, and "good basic helo technique" is kicking your keester today.
Whenever I lapse into the slide-it-on routinely, I'm soon back feeling for the ground and jarring teeth. 350's will show you where the pilot is wanting.

This aircraft is "precise" and little change in trim and effect is apparent in the seat of one's pants. More than once I've thought I was definitely down and bottomed the collective only to have it drop the last couple inches. "I" was "down and through flying" but the helo wasn't.
When all else fails- stop overcontrolling, hold it still- and land it like any helo. The slide on is admitting defeat and she knows she whipped you.

as355f1

It is an old belief that the height of the main rotor vs the height of the tail rotor is a reason for hovering one skid/wheel down, this is really not correct. All the forces developed by the machine are summed at the center of gravity, which is considerably below the main rotor head.

The aerodynamics of the machine make it such that the higher the tail rotor, the LESS it leans in a hover! Helos with the lowest tail rotors have the most lean, believe it or not.

High tail rotors produce a rolling moment that subtracts the left lean (for a US type system). For a given helo, if the tail rotor is centered on the tail cone, the left lean is about 5 to 6 degrees. If that tail rotor is moved up a few feet to the top of the tail, the lean is reduced to 3 degrees or so.

A question for the group:

In what axis does it wiggle - yaw or roll?

How fast are the wiggles _ in wiggles per second?

From my days flying the D model, lo these many years ago, ISTR that the answers are Yes and I can't count that fast. :D

I always tried to keep my hands as still as possible and my feet moving as fast as possible - land the thing using the tail rotor instead of the main rotor for precise positioning. But nobody alive can set one down gracefully every time. Most of the time, but not every time; eventually it will embarrass you. I've never flown any flavor of B model, and never one with a high skid gear, so those may be different. If the fuel tanks are baffled now, that's a big improvement, but I only noticed that in cruise, the notorious AStar shuffle. When landing, I was always moving things faster than the fuel could move in the tank, so the inertia never seemed to build up.

I loved the space between the seat and the door. When I moved into the AStar from a 206, all that space was wonderful. I finally had a place to put my bag where the pax couldn't get it and take it downstairs with them. 140 gallons of fuel, speed to get somewhere before burning all of it, a heater, a defroster - hell, I was in paradise. A little twitchiness in landing was only a minor annoyance. The hand grenade LTS101 built by Lycoming was what worried me. Those who still use them say they're much improved now, but the offshore operators abandoned them long ago.

Having flown over 3000 hours on AS 350/355 series and landed most any kind of place, I don´t dare to explain WHY is so hard to do a soft/Bell type of landing, mostly on hard surfaces, like concrete or others alike, but my two cents on HOW to deal with it are trown in:
It's a nice trick to land moving a bit forward as it is to put the wheight on the right aft skid and maintain it in that position until the bouncing stops, then really easy on the cyclic, put the rest of the right skid on the ground, maintain again without stirring the pot, and low collective to land the left skid. I find that if you want to land without feeling that frustating sensation of rebounding on the right skid first and then on the left, due to a really stiff landing gear (cross tube), you have to go through three fases:
1.- Right hand aft skid
2.- Right skid
3.- Left skid
If you don´t move the cyclic nothing more than strictly needed, you might get a soft landing out of every 10 tries.
Good luck :ok:
P.D. In the other hand there is no better landing gear to do toes or partial landing in stones and other weird places in mountain terrain IMHO.
Buen vuelo

Agree totally with Devil & Matador...

Re: the ugly wind, yes, right quartering and/or straight up the tail upslope is very tough - mix in some down drafts from high surrounding trees and you have your hands full. The advantage with the Astar is you do have lots of range fore and aft cyclic, vs others where you have to be very careful not to run out of aft cyclic when facing a slope. I have had to hold it in a hover (against my wishes) when a precise landing plus or minus 8-12" fore and aft and left and right is required, until I have that moment of respite from the tailwind, then plant it on the log or log pad .

As far as moving the pedals, everyone has their own technique, but I try to move the pedals as little as possible - the tail rotor is so powerful (which is good), that even small movements of the pedals back and forth exaggerate the wiggle (at least I have found that).

An interesting thread......

As a very! inexperienced pilot who has flown a number of different types I always found the Squirrel to be a fantastic aircraft.

I learnt to fly rotary in it and although it is a bit jumpy in the hover after some practice I never really noticed it.

As for the throttle I know other aircraft where the throttle is poorly placed for single pilot ops......i.e. Gazelle

Ralph

Mr Lappos, I don't know why the question was framed as a "wiggle." That's a PIO, everytime, in these. 350's hover just fine, but as one descends and the flow changes, it'll pitch, roll and occasionally yaw, small but quick attitude changes, and start translating in response, if correction not expeditious and accurate. Controls are quick (the engineer type was right- "precise"), so small changes in position gotta have really fine control adjustments. That can be a challenge some days when the death-grip cramps are constantly being shaken out...

It's one of the few helos I've flown that seems as quick in the hover as in cruise. Real joy, harmonious and stable without being ponderous. If only the hydraulics were as nice...

Thinking back to PoF, I think the right skid low issue is actually a result of tail rotor drift??

As John Bicker told me during my early squirrel days, "It's all in the pedals."

Thanks JB, You're a legend, and I love you!

Devil49,

Thanks for that info, it does seem to me the comments center around a yaw control that is both powerful and sensitive, and that we are talking about a bit of Pilot Induced Oscillation - PIO. Not much, I'll bet, and easily compensated for.

The reason why it gets worse as the aircraft descends is probably little to do with flow and such, and lots to do with the pilot getting tighter on the controls as the ground nears.
The reason why I asked about the frequency of the wiggle is that the airflow around the machine cannot generate a 2 or 3 Hz problem, because the aerodynamics are slower than that, but the pedals surely can. NOTARs are a bit slow on the yaw response, for example, and they captiolize on that aerodynamic force.

Generally the PIO can be fixed with a bit of damping on the pedals - like a door closer, a small hydraulic cylinder is imposed that makes the pedals hard to move too fast, but easy to move slowly.

Even a Huey is sensitive in the pedals, and likely to get a tad squirley when a pilot dances a bit too much on the pedals.


JNo,

Yes, I agree the right drift is exactly why the skid is low. The tail rotor is producing a force, (all US convention hereon) that pushes the helo to the right, a factor called "translating tendency". When the pilot corrects the right drift, he automatically rolls the aircraft a it to the left. When everything is settled, the roll attitude is about 2 to 3 degrees to the left, so the main rotor thrust is tilted a bit to the left to counter the tail rotor thrust to the right. 3 degrees tilt equals 5% of the main rotor thrust.

There is a hard to kill belief that the height of the tail rotor makes this worse, as if the comparison between the tail rotor hub and the main rotor hub height is somehow a part of the aerodynamics. Sadly, this one will not quite go away! Actually, the higher the tail rotor, the LESS the hover bank angle is!

Those who fly S-76 note about 2 to 3 degrees, those who fly a center line tail rotor (A-109 and any fenestron bird, for example) can you tell us what you see on the roll gyro when in a steady hover, no wind? I predict about 5 degrees or so. Comanche leaned at 5 degrees with its centerline fantail.

My thoughts are that all of you that experience this wiggle are ex Bell pilots.
I have never had the problem, nor have my students.

Around all helicopters close to the ground there will be patterns of air flow that are random due to a multiplicity of reasons. These air flow patterns will effect the tail and main rotors and as pilots you are trained and practiced in hovering. May I suggest more hovering practice with a relaxed and alert brain!
Coanda effects and the like are possible reasons. Some tail booms have strakes, some have had strakes and have had them removed, some do not have strakes. I think strakes were/are fitted for other reasons.

Head Turner:
There are lots of those who experience this who are not ex-Bell pilots.
Seems to be unique to the AS-350 series, although I have seen something similar, with less intensity in the Bell 407.

My company's looking at buying a Squirrel that comes with both high and low skids.

Planning to fly it in both configs and see but apart from the obvious change of ground clearance and dynamic rollover potential, what else is different when flying the low skid version ? Less 'wiggle' ?

All my time is in low skid models, and IME the low skid makes it harder to set one down gracefully. Also, the tail skid is below knee level when on the ground, and it is entirely possible to strike the ground with it when hovering with an aft CG and/or a tailwind. Avoid low skid gear at all costs.

Thanks GLS,

Useful to know, especially as many of our landings are confined and high skid model can be 'squirrely' enough.

Is it nothing to do with the front and rear legs being a different length, and the bushy tail moving from side to side as they run???:confused: :O :O

Is there a difference between grey and red versions as well??

The answer is yes, they all do in a certain part of the flight envelope - probably the cruise.

Certainly Brit military Principles of Flight teaching is thus: put simply, tail rotor roll (ie hovering left or right skid/wheel low, depending on main rotor direction of rotation) IS a consequence of the different height of main and tail rotors and is designed in to avoid being left (or right) side low in the cruise. As the fuselage pitches further down with increasing speed, at normal cruise, you have a (laterally) level floor. Much more comfortable, and less disorientating in IMC. However, inevitable design compromise means that laterally level fuselage in cruise (tail rotor and main rotor level) inevitably means in the hover when more nose up (tail rotor and main rotor NOT level), there is a lean to one side (towards the advancing main rotor blade).

Check out side on pictures of most conventional helos in the cruise to see that tail rotor is usually level with (or closer to) the main.

And I did say "put simply"!! With due consideration for Danny's bandwidth.

Astar rotorhead direction?
 

Surely it has been asked before, but what's with the clockwise direction of travel for the rotors?
Just the french engineers being french??

Steve,

Looked at many single-rotor Russian helicopters lately?

Maybe anti-clockwise is just the Americans being American...

Jonathon Swift wrote a whole book about the ability to argue about arbitrary things!
As lately seen, Americans go Right when more power is added, the French and Russians have always gone Left!

There is obviously no 'better' way to have the rotor rotate.
Legend has it that the French got one part of a Flettner machine as war reparations and used that for their engineering, and since it turned clockwise when viewed from above, they stuck with it. Given the relative maturity of the French rotary wing engineering prior to the second war (they had the first hovering helicopter in 1909) that's a bit far fetched.

Anything to do with the relative conventions of piston engine direction of rotation in the early days?

But that had two contra-rotating rotors, didn't it :confused:

Hi,

Have a look here

http://www.pprune.org/forums/showthr...hreadid=105978

Cheers

ATN

AS 350 B-3 Engine Failures
 

An As-350 B-3 recently experienced an engine failure during takeoff in Sierra Vista, AZ. Has anyone experienced similar difficulties with this model machiine? We are currently operating a B-2 and are due to get a new B-3. Our pilots are expressing concern with opering this new aircraft in the mountains at night.

None that i have heard of in Oz, BUT

flying any single engine helicopter over mountains at night is something you SHOULD be concerned about. At least tell me you will be using NVG?

Statistics can be bent anywhich way, but engine failures are not a rare occurence, and rarely are failure statistics recorded where the failure does not result in damage or injury. For the pro single engine mob that are bound to be wound up by this statement: when it all goes quiet at night, out to sea, IFR, over inhospitable terrain or day care centres, console your selves in the statistics of how safe single engines can be.

And how much money was saved by the operator to put you there. Who knows, maybe they put it all into accident insurance for the sake of your loved ones!
:8

We have a very solid track record with tens of thousands of single engine flight hours. Good maintenance and professional pilots. We do have a few intermediate twins but they are not capable of operating even duel engine at the altitudes and temps we experience. OEI capabilities are even more limited. No we are not presently NVG's but we are working on it. Any knowledge or increased understanding of the machines we operate goes along way toward keeping our operation safe. Thanks you for your input.:ok:

Great machine, great engine. ****ing computer. I'm flying one of the first B3's to come off the line. We're within (knock on wood) 150 hours of engine overhaul with no problems. Unscientific observations point to Texas built machines having problems, Canadian built not so much. Please Eurocopter, lose the DECU, or FADEC, or whatever you're calling it now. That would make it the near perfect machine.

They're probably using a 386 :yuk:

Phil

A-Star "Jack Stall"???
 

This term "jack stall" is a new one on me....anyone out there that can enlighten me? Was used in disussing a recent 350 accident and was related to large agressive control movements and the inability of the controls to function as expected or demanded.