How close?
 

Wait until you get to about 40 seconds and then estimate his rotor clearance :eek:

It was “just sufficient” to avoid a track and balance issue .

It was greater than the Mexican Blackhawk we saw recently!

When you are apt to get shot at...especially in today's threat environment you do what you have to do to avoid giving the enemy an easy shot at you.

Nothing unusual in the video.....increasing height a bit in order to dip your rotor blades into a turn....common practice when flying low in combat.

Laying the aircraft over on its side to pass between trees rather than popping up....is another maneuver that would have Nutty peeing his pants I bet.

Flying under power lines...bridges....down winding river beds....in ravines, canyons.....anything to hide is on the menu.

You trade risk for gain....as in all tactical situations.

This video was made to show off the BO-105 rather than demonstrate tactical flying but gives a good idea of what it like.

I never took a hit flying low and fast which is how we learned to do it in flight school but the Army in some very bad thinking moved away from that until the NVA showed up with MANPAD SAM's....then things changed.

Not really, I’ve done all that, remember I used to be on RAF SH for my sins, I much preferred to try and get some kip down the back..

Impressive flying of the BO105, here is the US doing similar SASless…. Sorry I couldn’t resist ;)

Karl (Charly) Zimmermann in the video SAS, he came to Oz demonstrating the 105 and stopped by, filled the aircraft with we pilots and took us on a never to be forgotten low level, one which none of us ever wanted to repeat.

All good things come to an end, his final demonstration. 9/20/89 TUCKERTON, NJ MBB BO-105 N5353V

:(


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I hadn’t seen that video before. I displayed the Puma at the time CZ began doing his and that, to me, seems a very basic error.

Agreed, he had nowhere near enough height at the apex to complete that manoeuvre - all he had to do was roll wings level.

However I believe the 105 had similar pitch/roll couplings at high disc loading as the Lynx so he could have been caught out that way.

As for low flying, the challenge in South Armagh was to get from Bessbrook to Crossmaglen keeping the rad alt low light on all the way with it set to 50'.

Pretty sure it was Siggy, not Charly, who died during filming - my non-pilot kid brother remembers meeting Charly some time after that (and found him modest, patient with questions and extremely pleasant company)

Although my first employer in civvy street had technically qualified me on Bo105, I didn't actually learn to fly and operate it even remotely how I should've until I did the NLB (Scottish and Isle of Man lighthouses) training. It was here that we did a speed-reducing straight-and-level exercise around 400ft agl at the end of which, around 30-40kts, the instructor told me to put in hard right cyclic. The aircraft promptly fell out of the sky - opposite cyclic having no effect at all - and as Crab says it could only be recovered with collective just like in the Lynx.

Confusing
 

For a detailed discussion of this accident video here on Pprune see: https://www.pprune.org/rotorheads/32...ck-2006-a.html

Karl "Charly" Zimmermann
Siegfried ("Siggy") Hoffmann (sometimes referred to as Hofmann, or even Hermann)
Siegfried ("Siggy") Schwarz

Plenty of room to get confused. Too many 'mann's, and too many 'gy's. The only thing I am pretty sure of is that Siggy Schwarz is doing well.

And so is Charly Zimmermann, at least 3 years ago

skadi

Just to add to the above, It was Hoffmann in the 105 accident video and in the MBB demo video above. Last I heard Zimmerman was retired in Germany and Schwartz is/was involved in both Red Bull helicopter ops.

T and B,

Are you describing a nose tuck to the right during a hard banking turn to the right....which increases the rate of turn and an increase in the rate the nose dips down into the turn?

A remedy for that is full. opposite pedal...in a right turn meaning full left pedal to the stop until the tuck and turn are remedies by the nose picking up and the rate of tun decreasing.

Adding collective would require the input of left pedal to counteract the increased torque and if only enough was used to balance the additional torque the nose would still drop.

We encounterd the same response in both the 105 and 117 and used the same recovery technique taught by the Factory Training Pilots during our Annual Factory Training..

An operation I was on lost an aircraft due to that....a low level steep turn to the fight with an increase of Collective caused the aircraft to experienced a nose low pitch attitude and an increase in turn rate which was aggravated upon the pilot increasing collective setting in an attempt to counter the rate of descent.....the aircraft was written of and only minor injuries to the Pilot and Crew were sustained.

That proved the need for annual third party training which we undertook by contracting with the Factory by having Annual visits by their Training Pilots.

I would imagine that might apply to most helicopters.

Perhaps Brother Dixson could expound upon this for us.

Thanks for the clarification on names chaps, interesting how the media seems to reference an incorrect individual.

hi SASless, the demo I had showed the ineffectiveness of opposite cyclic which was countered by dropping the collective; don't remember what we did with the pedals but I should think it did involve a fair amount of left boot. Couldn't agree more about the need for training from people who know what they're talking about, not some TRI who's never been shown the vices of your particular aircraft. I DO remember that the lesson had a salutary effect - the ship we worked off (NLV Pharos) was configured so that USL (or sling-load if you prefer) ops involved only left turns.

That was Siegfried Hoffman, not Karl Zimmerman. Just watched it three more times and am still wondering about the cause, as the rotor shows no movement toward a recovery, so I’ve always thought about other possible causes.
As to whether the roll rate or pitch rate was a problem, perhaps a few observations. We rented a BO-105 prior to the UTTAS fly-off with Boeing, to see what the competition rotor was like-advantages & shortcomings. It was what we expected in terms of the couplings, but just stronger, because of the higher effective blade flapping offset in the rigid rotor. Same counterclockwise rotation. So, get up to speed and pull back on the cyclic and the smart pitch rate is accompanied by a couple right roll…..same as our articulated rotors in say the S-67 but less in magnitude because of the lower odds set in the articulated rotor. Push forward on the cyclic and you get left roll. Put in pure right roll and you get nose down and the opposite with left roll. Gyroscopics at work. The problem with this flight path on the video is there does not appear to be any rotor movement toward correcting the flight path, and especially given the background of that pilot ( had the honor of flying a B-117 with him ) I’ve always been suspicious of some other factor at work here.

There was some comment re collective in maneuvering flight. NASA issued a contract to Sikorsky re investigating the maneuverability of the S-67 with and without wings and the effects on achievable max load factor. One of the interesting results was that independent of wings on/off, we achieved the max load factor ( talking about up and away speeds, beyond bucket speed,not hover ) at 70% collective. At higher collective, rotor stall effects were in play, and at lower collective, rotor thrust was in play. By the way, we used that approach doing all the structural demonstrations on the UH-60 and SH-60, with the concurrence of the military monitoring entities.

I am pondering if we might be talking about two different things especially if you are. involving underslung loads into the mix.

Having carried a couple of Sling Loads on my time...in all sorts of helicopters from 206's to Chinooks....Flght Control limitations never played a role in how we conducted those operations....weight limits of the Hooks, power available, and in some aircraft the amount of "Pedal" available due to wind direction and power required sometimes reached a limit but not cyclic control.

What we were doing is low level very steep turns at higher speeds at high gross weights.....as part of evasive maneuvers or in keeping a door gun pointed at a point on the ground to ensure max time for the gunner to engage the target.

As you exceed about 60 Degree Angle of Bank....the natural tendency of the aircraft is loose some lift due to the bank angle and thus demand more power meaning increasing the collective....but by doing so....that also provides yet more bank angle with a natural cyclic response by the Pilot to counter that.....and if the nose is allowed to drop then that rate of change is increased as the collective is pulled with the natural pilot response of adding aft cyclic. As the Collective pull continues you can experience that loss of Cyclic effectiveness and without using that full application of pedal....you find yourself riding in a fancy yard dart if you are close to the ground.

That is what reduces cyclic authority.....and when you reach that stage of the game....you need to lead with full opposite pedal and as the nose comes up....a slight reduction of collective will assist in the recover.

Wait a sec. If one rolls into a 10 degree bank ( for instance ) and keeps the same speed. The aircraft will lose altitude and its not the rotor losing lift its the rotor thrust vector sum arrangement has changed…..or am I missing some key part of the premise?

You got it....the follow-up question is how does one correct for that in angles of bank at say Sixty degrees or greater and does Collective input create a rolling input?