BO105 fatal accident back in 2006(?)

[Ready2Fly]

Hi,

i came across this video (http://www.youtube.com/watch?v=IiEfX3PDzTc) on youtube and wonder whether anybody of you does have any more information about it. I could not find anything yet. Rumours say it was flown by... well, i do not want to put a name here but in case it was true, he should have been one of the most qualified pilots on type. Very sad to see something like this happen even if it already happened years ago :(

Apologies in case this has already been discussed before.

Rgds,
Ready2Fly

[widgeon]

http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001213X29473&key=1

http://www.ntsb.gov/ntsb/GenPDF.asp?id=NYC89FA220&rpt=fa

I think this is the one , pilot with over 8000 hrs . If i recall correctly they were filming for Wings of eagles and the pilot was called Ziggy.

[skadi]

This accident was in 1989 and i am sure, that the pilot wasnt Charly Zimmermann. As far as I remember, it was Siegfried Hoffmann, former Chief Testpilot of MBB.

skadi

[Flying Bull]

Hi Ready2Fly,

seen that the video the first time :(

Known trap on Bo 105s, in steep right turns there might not be enough control to roll out again - so better be avoided close to the ground :(
Same problem might occur on BK 117s.

Greetings Flying Bull

[SASless]

Perhaps not enough cyclic but always plenty of left pedal....mash it hard and fully to the stops.

[A.Agincourt]

Left pedal, lower collective and aft cyclic, commensurate with height for the later two.

[Ready2Fly]

I read about the limitations concerning speed and bank angle in the FLM. What puzzles me most -beside the fact of the accident itself- is, that even pilots with that amount of knowledge -and i guess it is without a doubt to say that he was fully aware of the limitations- still get caught out that badly.

I do not think there are too many people around doing that kind if flying at about 75ft AGL ( := ) but it reminds you in a drastic way of how fast things can go pear-shaped.

In case it was Siegfried (Siggi) Hoffmann i saw him in another video (BO105 - The flying tiger) and was amazed about what he (heard it was him) did in low level flight - in a forest - with the rotordisc one or two feet above the ground (i guess the trick is not to use more than 30 degrees bank angle flying that low but i am not even rated on type).

[SASless]

Would not easing the turn....forward and left cyclic (if possible) be a better move than adding aft cyclic which works to increase the angle of bank due to the coupling.

Decreasing the collective (as much as possible) and adding full left pedal is the quickest and most effective method of recovering from this situation.

Making left turns when close to the ground prevents the onset of the dangerous coupling situation.

[Shawn Coyle]

You will also be able to notice right at the end of the video, as the smoke starts to rise that the helicopter crashed downwind.
The other issues with regard to BO-105 maneuvers notwithstanding, the 'wingover' was from into wind to downwind and that probably contributed slightly.

[Flying Bull]

Hi all,

if you watch the video closely - you'll see, that from the point, where the pilot might have recognized the problem to the crash is less than 2 seconds.
Even if you are quick recognizing, that this time the planed manover isn't working out - and even then, with the right plan at hand to react, at least a second is gone before inputs start to work.
Then the bird has to react - and the induced movement has to be stopped and counteracted.
I doubt that anybody could get out of the situation - with entering with the parameters the bird had.
(As far as i have read, the board remarked, that he tried to recover)
Even deliberately entering the situation with enough height to recover - will scare the s*** out of you.
The Bo105 is really fun to fly and can take quite a beating and is mostly forgiving pilot errors - but not all - and the line is sharp between still flying - and sudden stoppage....
I hope everybody playing around with Bo and BK see that video and keep it in mind when entering steep turns to the right - especial at low level.

Fly safe!

Greetings Flying Bull

[manfromuncle]

What should he have done? Start higher? Bank less steep? Or just pull more collective in the turn?

[griffothefog]

Been there done that, and if you need to recover, I agree with Sas, but bear in mind that if you are being filmed and want the turn to look pretty you may not want to look "flat" coming out of the manouver and that combo could be the last one:{
I'm no expert but have scared myself ****less doing that and have taken the chicken ****/easy way out even though its not pretty... Bloody red face though:eek: Great pilot RIP.

[SASless]

Griffs me lad.....perhaps you picked up a few of my less than stellar habits from all them many years ago!;)

[VeeAny]

Just out of interest, what is the cause of the Steep right turn problem in the BO-105. Is it a hydraulic problem like seems to be prevalent in the squirrels.

You've just got me thinking with my 'try and stop people crashing' hat on. If this can happen to a man as obviously experienced as this then we are probably quite remiss in the things that get missed out of type rating training. [Don't read anything extra into this just a thought out loud].

Not a thread hijack, I'll start another on that soon.

Any 105 pilots care to clarify ?

Gary

[widgeon]

http://www.rotaryaction.com/pages/firebirds.html

this was the film he was practicing for , note the aircraft was still in primer and had some of the mock up pods already attached. The 105 was going to be one of the "enemy" helicopters in this film.

[Brian Abraham]

Great pilot RIP
Griff - all the company pilots went for a ride in the 105 with him when he was demonstrating it in Oz and scared the pants off all of us, low level down among the trees. Never so glad to get back on the ground in one piece. We all had our opinions as to his longevity and unfortunately were proved correct. No matter how good you are, when you sail close to the edge it doesn't take much to bring you unstuck. And yes, I've stubbed my toe more than a few times.

[griffothefog]

Brian,
I guess we are all great pilots until the sail rips....:(

[skadi]

VeeAny,
its no hydraulic problem. In slow and steep right turns the cyclic could reach its stops, therefore the limitations in the RFM. Long time ago, it caught me once, when turning downwind in a low recce over the intended landingspot. My speed and bankangle was just enough, but reaching the stops of the cyclic wasnt a comfortable feeling.....
Somewhere in my papers, i have a copy of the explantion of this problem, as far as i remember, the author was even the pilot of that sad accident. I will try to find it....

skadi

[Lplates]

Hi all

So why is there a sustained right rolling moment with full left cyclic. I can appreciate that the turn will tighten due to the obvious aft cyclic being used to climb and hold the attitiude but don't understand why it refused to roll out with left cyclic. Is it related to rotor direction!

Regards Lplates

[Helipilot1982]

Am i correct in thinking the film was retitled 'Wings of the Apache'

[DennisK]

Having studied Hoffman's B105 manoeuvre, it occurs to me that he was experiencing a fairly well known handling difficulty that can result during the steep 'wing-over' recovery, especially from an into wind low level, low speed entry.

If the speed is allowed to drop below the transition lift point at the top of the manoeuvre, or even to a zero speed, I have found it is vital to regain translational airflow to obtain full disc authority for the normal recovery.

I hate to admit, that in two instances, (albeit in 1213 displays) I have experienced this 'loss of lift' condition, but fortunately on both occasions I had sufficient height to regain translational lift speed in the descent. It seemed to me that Hoffman did not have that height and during the following steep descent where there was not sufficient forward airspeed to regain the required lift, the 105 simply 'fell' into the ground.

I know that on one of the occasions I experienced the problem was when I failed to achieve the correct 'gate' speed for a 270 degree 'wing-over' following a 'toward the crowdline' level approach into a stiff breeze.

In the second half of the 270 degree heading change - the resultant tailwind significantly slowed the recapture of translation lift. The unexpected loss of immediate cyclic response and loss of height gave me more than a second of concern.

I now don't do 'into wind' display wing overs without an extra margin of 'gate' height and speed for the manoeuvre entry.

Not sure this is totally relevent to the Hoffman accident, but I do recall having a conversation with him on the subject at the 1978 Farnborough display, where he performed the first Bolkow 195 Loop I had seen. He certainly knew of the possible condition then.

Safe flying to all,

Dennis Kenyon.

[FH1100 Pilot]

Dennis, as I have 2,500 hundred hours of 105 time and have watched this video clip and over and over and over, I'm inclined to go with your assessment while rejecting the "infamous Bolkow running out of left cyclic" thesis. I'll bet that Ziggy dearly wishes now that he'd started that maneuver with 10 or 20 knots more airspeed...or alternatively had started it on the downwind run instead of the up.

[Gaseous]

I dont get it. The downwind element. I understand landing downwind is a problem due to transition through hover to backward flight to get groundspeed to zero but in a manoeuvre such as this, how is the groundspeed relevant?

If Ziggy entered the manoeuvre at say 70 knots airspeed and that was enough to safely complete, 70 knots IAS upwind is the same as 70 IAS downwind. What difference does the groundspeed make? The rotor system responds only to the airmass it is travelling through. The groundspeed is irrelevant to the actual physics of the manoeuvre.

It seems to me Ziggy's problem was too low, too slow (airspeed), too steep, too mad. RIP.

Can you explain why the rotorsystem responds differently downwind, if the airpeed is the same in any replies? Thanks.

PS. Ive re-read Dennis's post several times but I still dont get it.

[DennisK]

Okay ... the differences is 'inertia.' Something I routinely demonstrate in PPL steep turn and quick stop training.

In display manoeuvres, and for that matter any manouevre involving a 180 degree change of direction parallel to the current airflow, inertia of the airframe IS directly related to 'groundspeed.' The effect is more significant on the heavier helicopters.

Given a 25 knot breeze and a rapid 180 degree turn, the airframe IS NOT going to accelerate instantly with the reversed airflow. Indeed in demonstrating the effect, I've noted 3/4 seconds delay before the ASI indicates a positive reading even though the ground below is passing by at 20knots. That time is more than enough to lose the little height Hoffman appeared to have had based on my video viewing.

The difficult thing to get ones head around, is that in a steep nose down attitude with 'nothing on the clock' the cyclic has to be pushed further forward to regain translation lift as quickly as possible to enable the subsequent aft cyclic to be fully effective!

At Rochester in the mid 1990s, I saw a similar situation, when a Hughes TH55 sank into the ground turning off a strong wind in a low level steep turn. It does happen.

We can all observe the 'inertia' effect by practicing at height. Commence a 30 knot rapid turn on to a downwind heading and monitor the ASI. The reading will often decrease to zero or less than translational lift speed for a second or so.

I'm suggesting that may have happened in the Hoffman case. As I noted in the earlier post ... it has certainly happened to me, albeit it won't again.

Other views very welcome please. I'll bet my bottom $ Nick Lappos has the real answer!

Take care all,

Dennis Kenyon.

[InducedDrag]

Dennis

I am definitely not trying to argue, but I just must protest.

There is NO inertia involved in turning downwind or upwind. The helicopter does not know any different. It is flying within the "sea of air".

Your idea of inertia would be analogous to saying that a boat on the current of a river, turning from traveling against the current to going with it, takes a moment to gain speed.

Or even a more extreme example is....that it makes a difference turning east to west.....because the earths rotation will either add or subtract from our speed.

The only way there could be a factor, which is quite possible I will add, is if a steep wind gradient exists between the ground and the moving air mass. This can most definitely sap energy from an aircraft descending through it turning in the manner shown in the video.

[DennisK]

Hi Induced Drag,

I'm trying to think up another way of explaining the condition. Not sure where I'll be leading myself even!

Our dear friend Isaac Newton tells us that every body in a 'uniform state of motion' continues in that uniform motion until acted upon by an external force. That, as we all know, is inertia, ie movement or lack of movement relative to space. Much the same as the pendulum of a clock swings relative to space, not the clock it sits in. Ditto a gyroscope. In the case of the pendulum it has a name. Cycloidal error. (Sinsinoidal)

So to try and relate this to our aircraft - its inertia is relative to space, which in its simplest term is relative to the bit of ground sitting underneath.

So let's say I am at the top of a wingover, ASI showing 15 knots in a fifteen knot wind. My position relative to space/earth underneath is static, and the inertia I possess is zero. The only energy I possess is the potential to fall to earth under the influence of 1G. ie ... 'Potential Energy.'

Now to achieve some speed I need an external force applied to accelerate me. Well in the instance I have given, I only have the wind and gravity.
Yes, as I reciprocate 180 degrees, the 15 knot wind is applied to my airframe, but I am not going to accelerate in a micro second to 15 knots in the opposite direction, and depending on the aerodynamic drag of my hull, that may take a few seconds. It is interesting here that the more streamlined my airframe, the slower the acceleration. A nice big draggy helicopter will speed up more quickly! (until it equals 15 knots groundspeed, therafter it becomes less efficient)

I hope I am making some progress here!

So we have a situation where, my airframe is at zero or low inertia for a short period and the only external force now affecting me is the 1G towards mother earth!

Now IF the time period before striking the ground is sufficient to allow the 15 knot wind to take full effect, and give me translational lift, I'm home and dry. But IF NOT, the 1G acceleration to earth takes precedent and you can see what happens. So we are talking here about extra height and extra speed for a safe wing-over manoeuvre ... something we all know.

All this of course assumes I don't increase power at some early stage, but since I am performing a low entry speed 'wing-over' manoeuvre followed by a steep descent, I wasn't planning on doing this until I need to level off close to the ground.

So in summary, I believe it is that short period of zero inertia when the aircraft is at risk. Plenty of height (ie time) to convert to speed is good. A streamlined and heavier ship has a corresponding higher period at low inertia and is correspondingly more at risk.

I can tell you that in display flying, the transition effect in a steep descent is as noticeable as the extra lift we all feel on a standard take off profile. The same thing happening in a steep descent takes some getting used to until one works out what is going on.

I haven't used any technical jargon or lift/gravity formulae here, since there are others better versed in those areas than me. But here's a plea. Nick if you are reading this, we'd all like your pennorth!

Best wishes,

Dennis Kenyon.

[Gaseous]

Thanks Dennis,

My head is still hurting over this. To paraphrase you, if I have understood correctly, the inertia is relative to the ground, not the air flow caused by the wind. This explains the proposed phenomenon neatly if correct.

My problem is based on my (infantile) grasp of Newtonian laws of motion. I feel the inertia should be related to the air flow, and that the ground is simply not relevant being in a different inertial frame. Am I wrong?

Its a long time since I did A level physics. I could well be wrong.

Edit: you just posted above as I was writing this. Apologies if you have just explained.

[Shawn Coyle]

Induced drag:
The boat analogy is not valid, as the boat doesn't get any of it's bouyancy from motion through the water, only by displacing water.

[ShyTorque]

Many folk forget that a helicopter isn't always in a balanced turn. Once yaw pedal is used, the rules change and inertia has much more effect. A wingover / torque turn is one of those occasions.

[InducedDrag]

Sorry, and with all due respect, the helicopter does not care about the ground as a reference point. (unless you hit it)

Inertia measured relative to the ground is not valid....just as it is not valid to say that a helicopter hovering at the equator has more energy then one hovering at the pole.

Sure it does from the frame of reference to an interstellar object....but that does not have any effect on the dynamic of flight.....Just as a frame of reference to the ground has no effect.

AIRSPEED is the the only measurement that matters to a flying object. It does not care if you turn upwind or downwind....so long as airspeed stays the same.

Like I said earlier.....it is possible that climbing or descending through a gradient CAN have a effect or flying in gusty conditions. This can add or decrease energy from the ship.....relative to it's airspeed.....which is the only one that matters.

[Gaseous]

Having spent some time with fount of all knowledge, Google, it seems to confirm my gut feeling that the inertial frame of reference relevant to the aircraft is the airmass it is moving through, not the ground. Indeed, the ground appears no more relevant than the centre of the solar system to the helicopter. If this is the case then being 'downwind' is also irrelevant in this context.

Load of examples such as the juggler here:http://id.mind.net/~zona/mstm/physics/mechanics/framesOfReference/inertialFrame.html

I realise this is at odds with Dennis's explanation and I hesitate to take a contrary point of view. NICK, where are you when we need you. Induced Drag is clearly thinking on the same lines as me.

I'd be happy to be proved wrong so as not to be at odds with Shawn, Dennis, FH1100, and just about everyone else but I can find no convincing physical reason to support the assertion that Ziggys accident was related his track relative to the wind direction other than ID's gradient explanation.

Come on guys, Ive got to be missing something here.

Edit: My interest is more than academic. I experienced a similar drop during an LPC a few years ago doing steep turns, fortunately at 1500ft. Lost a couple of hundred ft in a few seconds.

[brett s]

The way I see it, if you weren't looking at the ground & kept the same airspeeds throughout the maneuver when turning either upwind or downwind it wouldn't matter at all except for any different wind gradients you're passing through as another poster mentioned.

But because you are referencing the ground track & not airspeed when doing that sort of maneuver at low altitude the wind direction matters.

Biggest scare I ever got ag flying was the same sort of situation - heavy as I'd just taken off with a full load, field rows were directly aligned with the wind, turning downwind. Couldn't widen the turn to keep airspeed up because of obstructions on both sides, so end up with basically zero airspeed at the top. Dropping back down into the field with plenty of ground speed but very little airspeed yet, aft cyclic isn't going to help there. Ended up about 6" above the dirt with rpm bleeding off before stopping the descent... Bad choice on my part getting into that situation, it was definitely a learning experience!

[jab]

This example works for me since I have experienced it myself. During fire fighting in a reasonable wind, you try to take off into wind and get at least 40 knots on the clock before turning out. There are times when this is not possible and as you turn downwind you really have to be careful because you lose IAS and the helicopter descends with the loss of IAS and sometimes translational lift in strong wind conditions. The helicopter also accelerates very slowly with a few tons of water hanging below and even though I have been aware of this, it has still scared me silly more than a few times.

The principle remains the same as Dennis has explained, the helicopter has inertia and when turning downwind, especially if the turn is very tight, it takes time to overcome the wind gradient and therefore the IAS decreases, possibly to below transition. Without the translational lift there is insufficient pitch / power available to overcome the rate of descent established in those few critical seconds and a prang is very likely as in this example.

I agree that you are flying in an airmass, there should not be a change in IAS and there wont be if the turn is gentle. With a really tight turn the inertia is much more obvious and there is definitely a drop in IAS when turning downwind. It wont make a difference if you started the turn with sufficient IAS, as Dennis said, but it certainly will if you start the turn with the speed too low.

[Brian Abraham]

Oh dear, the downwind turn raises its ugly head again. :{ People have trouble coming to grips with the aircrafts relationship with respect to (a) the ground and (b) the air. Extensive discussion here, but as usual be careful what you take on board from the posts, some poor understanding of both aerodynamics and physics evident, but if you visit the military forum often you will be aware of who to give credance. http://www.pprune.org/forums/showthread.php?t=275575Well we can but try and educate. Please read the following and note the last paragraph. http://www.flyingmag.com/article.asp?section_id=12&article_id=27&print_page=y

[jab]

Hi Brian

Peter Garrison's comment is only valid for "normal" flying. Ziggy's turn was not what you would see in the circuit being practiced by students and involved a rapid change of heading out of the wind. Dennis mentioned IAS dropping close to zero during his shows, or at least below transition, resulting in insufficient lift to overcome the rate of descent. At least he had sufficient height to recover. It appears this happened to Ziggy but he was unfortunately too low to escape. My example has similarities and is based on experience. I believe Dennis' theory as to the cause of the accident to be reasonable, insufficient airspeed and height for a high rate of turn out of the wind.

"There, but for the grace of God, go I." RIP

[Gaseous]

Thanks Brian, all is now clear. I shall persue this no further.;)

[Shawn Coyle]

Ask any model aircraft flyer or ultralight pilot about the effects of turning downwind, and they'll all agree there is a significant issue.
My rule of thumb is that if the windspeed is more than 25% of your airspeed, turning downwind will have a noticeable effect on flightpath.
And doing wingovers from into wind to downwind catches everybody out the first time. anytime You are maneuvering vertically, energy with respect to the earth has to be considered.

[InducedDrag]

I am sorry but I still dont buy it.

With regard to asking a model aircraft pilot, their frame of reference is from the ground...which the aircraft does not care about. Now if the guy on the ground tries to maneuver with reference to the ground, then there will be issues.

I agree that if the helicopter pilot was maneuvering by ground track, he could get sucked into this. But if he flies by the ASI, the ship will still fly the same. (although ground track may look slightly different due to wind drift)

Again....I still hold that climbing or descending through gradients CAN have an effect on energy where it matters (airspeed). It is a technique that many sea birds use to stay aloft for hours at a time without flapping. This is why you observe the birds diving and climbing steeply. They are extracting energy from the gradient.

Here is a link:

http://en.wikipedia.org/wiki/Dynamic_soaring

http://www.wfu.edu/biology/albatross/atwork/dynamic_soaring.htm


Just to illustrate my point another way..... Imagine if during the wingover, the earths rate of rotation suddenly sped up twice as fast underneath it. The ground would accelerate and the pilot would suddenly see the ground passing under him at about 1000mph (near the equator). Ignoring friction between the air and the earth (meaning the air would not begin to rotate), ....would the helicopter suddenly have more "energy" to fly? Of course not....the helicopter only cares about the surrounding air it is flying in......the earth is of no consequence.......unless you hit it.

[DennisK]

This is bubbling away nicely. We still need NL's view.

Let's look at this condition from another viewpoint.

Imagine a 20 stone rugger forward standing stationary at Twickenham. You charge him for the tackle but you are 10 stone. At impact he will barely move but you'll bounce off and have a headache. It will matter not a tot whether there was a 20 knot breeze blowing at the time.

The reason is he possessed no positive inertia relative to the surface he was standing on. But you did.

Now visualise the same 20 stone guy heading for the touch down line at 15 knots. You are standing still this time. To throw him off balance you'd only need a gentle shove as he sped by ... 20 knot wind or no wind, the above example is sound.

The reason is, relative to the surface the rugger forward now possesses 15 knots x 20 stone of positive inertia. (I won't put it in ergs.) How well I recall the situation from my playing days. Get the big man when he is moving fast!

Al I can say lads is that you won't ever get me performing a rapid 180 degree turn into a downwind situation at low level. A few hours of experience taught me that a while ago.

Can we return to the 'earth moving' condition. Contrary to what has been said. If the globe were to instantly rotate from stationary to 1,000 mph, then the poor guy standing WILL for a few seconds similarly find himself launched across the surface at the same 1,000 mph. Once the 1,000 mph wind took effect however, he would slowly find himself returning to a stationary position relative to the earth once more.

BUT ... IF he was in a vacuum he'd remain forever at 1,000 mph somewhat like a satellite!

The condition is there and perhaps a physicist can explain better it than me.

Over to you lads, and especially Nick Lappos.

Dennis Kenyon.

[Overdrive]

Correct this is is getting interesting!


The reason is he possessed no positive inertia relative to the surface he was standing on. But you did.



No, the reason is he has enough inertia to resist your momentum.



Now visualise the same 20 stone guy heading for the touch down line at 15 knots. You are standing still this time. To throw him off balance you'd only need a gentle shove as he sped by ... 20 knot wind or no wind, the above example is sound.



Now he still has inertia, but plenty of momentum, which you can "vector" with a glancing blow, maybe deflect him into touch. You would feel this inertia well enough if you stood directly in front of him. This inertia is why you can't stop him instantly, or even push him sideways at 90 degrees (unless you are bleedin' enormous, i.e., have much more inertia than him)


Inertia is resistance to change of velocity/direction, and is present regardless of whether moving or stationary.

[griffothefog]

With all respect to Dennis and all display pilots I think the thread has moved away from the reality of the crash... With over 3500 hours on 105's and years of crop spraying, that turn was BOLD to say the least :eek:

[Nubian]

I wonder about if it's not time to bring out the old Aerodynamics notes from PPL ground-school.

Why did we learn to keep collective pitch constant during our first hours?
Cause: The amount of power needed for hover, will allow acceleration and climb away once passed 12-15 kts (ETL) as the whole disc area is now more efficient, generating more lift over drag, than in a hover also making the disc more responsive/controllable.

Why do I drag this into the discussion?!

Well, in his manoeuvre he would turn from up-wind to down wind while decelerating, climbing, and bank hard. About 98 deg. if I remember correctly, so A BIT steeper than your average steep-turn:eek:

All of you know that operating down-wind is less favourable than up-wind, and the importance of maintaining IAS. However, if you fly with reference to the ground (in this case for practise for a film-shoot) you might unintentionally loose too much of your IAS, and even loose ETL. Now your disc is generating less lift for drag and it is far less responsive for your recovery actions.

IF in this case, he in fact lost ETL at the top of the manoeuvre, WITH the extreme bank-angle he had (his disc is NOT producing lift vertical to the ground at this point, but acted upon by earth's gravity generating a fairly high ROD), the only thing that could let him recover was to regain ETL by loosing ALT, which in this case he did not have much of...about 70 ft.

Back to the question about the down-wind/up-wind, if that has any effect. If he had done the same manoeuvre opposite direction, I am fairly sure the outcome would be much different as I am sure he wouldn’t have lost ETL and by that maintained control throughout the manoeuvre.

My 2 cents...


There are old pilots and there are bold pilots, but there are NO old bold pilots....

RIP

[SawThe Light]

An odd quirk of physics seems to be that a really dense cloud layer will apparently cancel out "inertia" and all those other nasties that wait to pull us into the ground during a "downwind turn".

For a demonstration of this phenomena, simply note the wind direction, climb thru the layer, once on top take up a heading into the wind previously noted and then commence a turn onto a reciprocal heading without any reference to the ground. Notice anything?

Or you could perhaps do a series of continuous 360's under the hood and try to establish which direction the wind is coming from.


STL

[ShyTorque]

Again, if the helicopter is being "pedalled" round the turn, i.e. not in balanced, banked flight, the rules for balanced, banked flight don't fully apply.

As usual, take the extreme example to illustrate the point.

Imagine a helicopter in straight flight.

The pilot keeps the altitude and applies no bank whilst rapidly pedalling the aircraft round 180 degrees. Just because it's now pointing in the opposite direction doesn't mean to say it's now flying in the opposite direction.

Any turn where the helicopter is yawed with pedal into a turn, to a degree more than that needed for balanced flight, as sometimes happens at low IAS, remaining forward airspeed can be rapidly lost, especially in a gusty wind.

Quite strong "negative" flapback can occur where IAS rapidly decreases through zero and to a negative value. This could pitch the aircraft rapidly nose down to a situation where possibly insufficient aft cyclic control remains to recover, until forward airspeed is regained and positive flapback occurs, naturally bringing the nose up. Negative airspeed over the horizontal stabiliser (now a de-stabiliser) can make this nose-down pitching worse. Close to the ground that could be catastrophic.

I saw 120 to 130 degrees nose down with no airspeed in a Puma HC1 a couple of times, once with at least one hydraulic pump briefly screeching as it cavitated; it's quite enlightening.

[dragman]

Ok, my 2 penneth, which will be quick as I'm having breakfast. If you look at the shape of the turn as viewed by us i.e. the radio controller pilot guy on the ground, it looks pretty symmetrical. This was mentioned before about trying to make the turn look good for the camera. By doing this with the tail wind present, he's got to lose airspeed halfway through. Bang.

Do this above 8/8 of cloud (as already mentioned) with 15 knots of breeze whilst using a particular cloud for a reference point, you'll be home and dry - your reference point is moving at 15 knots.

I find it hard to believe that wind will affect your IAS. Great discussion tho!

Cheers, DM

Quick edit here - look at the vid, doesn't look like the chopper was out of balance during the turn

And another edit - for the record, I agree that an out of balance maneuver would/could have significant inertia issues.

[dragman]

My breakfast has gone cold

[Gaseous]

The thread has polarised into the believers and non believers in the relevance of the wind direction and I'm not going to persue that further as I said. I now have it clear in my own mind.

To throw more into the bubbling pot, refer back to the video. It is conveniently time stamped. As the aircraft enter the turn it climbs and reaches the highest point of the turn at 11.06.12. At this point the aircraft is banked to 90+ degrees and runs out of momentum opposing gravity. Any thrust from the main rotor (probably little) is added to gravity pulling the aircraft earthwards at 10 m/s2.

At best the aircraft begins to accelerate downward as would any object in free fall as there is no thrust vector to oppose gravity. The pilot probably has his left boot to the floor but its not enough to keep the nose up. He has whacked in left cyclic and by 11.08.10 is just getting some response, but still has a bank angle of about 60 deg.There is not enough downthrust to overcome the momentum the aircraft has acquired earthwards. The result is inevitable at 11.08.12.

The aircraft was doomed achieving that angle of bank at that height.

Just 1 second of no force opposing gravity means you will end up descending at approx 10m/s or 1980ft/minute.

I would estimate the windspeed at no more than a few knots by the speed of the smoke and at no point does the aircraft look as though it got anywhere near losing translational lift. He was motoring all the way round. He lost lift 'cos his rotor was pointing in the wrong direction.

Just my interpretation of the video.

Thoughts anyone. I'll get me coat...

EDIT: I'm not testing this in my Enstrom (once was enough) nor my RC model but trying it in a reasonably good RC simulator I can't recover from bank angles over 90 degrees without losing significant height.

[FH1100 Pilot]

It's really sad watching that video knowing how it's going to end. Whatever maneuver Ziggy was trying to pull off there looked improvised and unrehearsed. I'd imagine that once he got up to the apex he probably said to himself, "Oh sh*t. This is not good." His airspeed must have been very, very low and his lift/thrust was pointing in the exact wrong direction. He was, as has been pointed out, at the will of gravity at that point.

Obviously he would have had to roll out of that steep bank and then recover from the dive. He probably did have the cyclic all the way to the left stop but the ship just wasn't responding what with the combination of low airspeed, bank angle and power applied as we know Bolkows are prone to (not) do. And there wasn't enough altitude to dive for more speed.

A long, long time ago when I was a mere private pilot, I'm ashamed to say that I crashed a ship doing something similar: an ill-advised ag-turn which I had seen done but never had demonstrated to me. Had I started with 60 mph it probably would've worked out okay. But I only had about 45 on the clock. At the end of the field I pulled the cyclic back. The nose came up and the ship...just...sort of...stopped, hardly climbed at all. I pedal-turned around, pointed straight at the ground now and went, "Oh sh*t, this is not good." Luckily I managed to get it more or less level before Bell 47 parts and pieces started flying everywhere. Result: One Bell 47G-2 destroyed. Completely my fault. I've lived with it ever since.

Difference between me and the Bolkow pilot was that he knew what he was doing...or so he thought.

[Brian Abraham]

To the believers of the downwind turn I offer the following experience. Where I flew 60-70 knots of wind was not uncommon. Taking off from a platform and climbing out at BROC (74 knots) turning downwind had absolutly no impact on aircraft performance. However there is an extremely strong and powerful VISUAL impact as the groundspeed goes from 14 knots to 134 knots. This is where pilots (my opinion only) run into trouble as they perceive the reduced climb gradient on the downwind as a loss of climb performance and naturally pull back on the stick to restore the perceived performance required. More attention to what the dials are saying negates the very powerful visual influence. As helo pilots we are a very visual lot in that we take our cues from what the terrain about us is doing rather than what the gauges may be saying (VSI, airspeed). What helo pilot has not been caught out and finding him/her self landing with the wind, however slight, up the tail.
The accident reports are replete with people who on turning downwind find the collective up under the arm pit and the aircraft still descending. Why? Because they've allowed the airspeed to zero out at some point during the turn due to them taking their cues from ground motion.
Used to see new guys occasionaly fall afoul of this powerful visual stimuli in another way as well. Enter the downwind with 60 knots of wind and decelerate the aircraft to zero airspeed prior to commencing the turn to base/final because they are taking their cues from outside the cockpit. On one occassion I unfortunately let the situation in a 76 deteriorate to the point where we just had enough height to make a recovery.

[topendtorque]

There seems to be an edict which resulted in at least one so far unanswered question during this thread.
That it is folly to roll these types too quickly to starboard.

Why is this so? is this a northern hemisphere and direction of blade rotation, bit of jungle talk?

As sasless has pointed out,
1) A/C rolling too quickly,
2) excercise aft cyclic, and top pedal ~ all the way ho-say ~ quick time. 3) Extra drag onto the M/R and clean air for the T/R should drag it upright. ~ as long as airspeed is available.

I think the running out of airspeed situation is a bit far fetched in this clip, after all the machine was getting along at quite a clip when it impacted.

However, deliberately pushing students into the downwind scenaio that Dennis K describes is standard practice around here. After all, if they are gullible it ambushes them into the dreaded VR envelope. ha ha . Descend, into wind, next time please!

Descending ~ downwind ~ decelerating
is just like
drinking ~ driving ~ death,
suit yourself, but not on my AOC thankyou.

The clip may illustrate that it once again illustrates the fallacy of coupling a non critical component, ~ the camera ~ however cheap~ into a seemingly safe operation.

[SASless]

Top points out my assumption of having forward airspeed when I talk of recovering by means of maximum use of left pedal. The discussion so far suggests that was not the case at hand or at best minimal forward speed.

The accident report stated the aircraft rolled to a bank angle of 98 degrees. I wonder at what point they measured that and if it was immediately before impact or a bit before that.

As I view the video, I notice the aircraft rolling but also a distinct tuck of the nose with a rotation about the mast (or are my tired old eyes deceiving me?). I wonder at what point recovery was impossible if an application of full left pedal was made? Would the nose have rotated to the right considering the angle of bank and lack of significant forward airspeed?

Or....was the rotation of the nose an attempt to gain airspeed such as in a torque turn but done at too low an altitude?

It would seem natural to me had I been caught in that situation, I would have been trying to level the aircraft with full left and moderate aft cyclic at a minimum and possibly full aft cyclic if I realized I was at or approaching the cyclic stops. I could even imagine a reduction in cyclic if I had hit the cyclic stops. The full application of left pedal would have been the last thing I would have done unless I had hit the cyclic stops.

Am I correct in assuming all that would be appropriate until the pitch angle of the aircraft started dropping below level? After the nose drops, it makes recovery at very low altitude very unlikely?

[DennisK]

Thanks guys for all the viewpoints, notes and handling experiences being put forward ... if nothing else, it has certainly exercised my brain for a while.

I feel that the major point that emerges from the Hoffman accident, is that with the quoted 98 degree banking angle, any vertical thrust from the M/R could only accelerate the machine further into its steep descent.

My standard display sequence does include a loop, but when I was first shown the manoeuvre in the 1970s, by a former world champion, he made it 1000% clear that at the highest point, the collective lever must be fully down and with a minimum 'gate' speed well above translation lift if the manoeuvre is to be continued. If not and with adequate height, it is a simple manoeuvre to 'duck out.'

I do understand that there is a body of opinion out here that absolutely disagrees with any helicopter display manoeuvres. Having flown a little over 1200 public displays in half a dozen types over thirty years, I mildly take the opposite view - that with the right training and proper understanding, display flying should stay as an exciting part of our industry and used to demonstrate the capabilities of the helicopter ... but having said that, I'm always listening to the other guys who take the reverse view.

Safe flying to all,

Dennis K

[Shawn Coyle]

Brian Abraham:
when you climb out and turn downwind, does the rate of climb stay constant? What angle of bank are you using?

[FH1100 Pilot]

Svenestron:Not knowing exactly what went through Siegfried’s mind at the time, I prefer to believe he was in no way “caught out there” due to any lack of judgment or planning, but was rather the victim of one of history’s most “inopportune sneezes..”
You're not a pilot, are you Sven? Wait, don't answer that. It's obvious. If you were a pilot, you'd know that even the best of us screw up sometimes. It's a sad fact, but there have been many times in my life have I heard of a particular aircraft accident and thought, "How could that have happened to HIM?!" But eh- it does. And it doesn't mean Hoffman was a bad person or a bad pilot. But he certainly wasn't a "victim" of some wierd and capricious cosmic sneeze. That may sound cold but it's not. He merely messed up and it cost him his life. Yes, it's tragic, but we pilots understand it.

I wonder how many times he had rehearsed that specific little demonstration for those particular cameras? Or, had he done something similar so many times before that he just went ahead and "winged" it (or parts of it)? In such a routine, everything must be thought-out well in advance. As a Bolkow pilot, I cannot imagine how that maneuver could have worked out any differently, given his entry speed and the "radical-ness" of it. I'm sure he knew at the top of that diagonal-loop-roll-RTT-whatever that it was all wrong. He should have been *much* higher.

We who have flown a while have all been there. We put ourselves in a position where our heart is suddenly jammed up in our throats and we go, "Oh, no..." Sometimes we pull off a miracle and squeak out of it. And sometimes we crash and it gets discussed ad nauseum on internet discussion boards such as this.

As Dennis says, if nothing else Ziggy's accident has generated exactly that sort of thoughtful discussion. It all gets stored in the back of my mind, ready to be recalled and used perhaps (but hopefully not) the very next time my hands touch the controls.

[Local Lad]

I think what Dennis and Shawn are saying is that, as you turn downwind from into wind - if you allow the airspeed to decay you can lose translational lift and it is reference the ground only by the fact that it is beneath you and without enough height, as you sink, you can crash into it. It isn't so much a fixed point beneath you, just a loss of altitude with a loss of effective lift...

[rotorrookie]

If turning from upwind to downwind is no problem and does not affect the aerodynamics and the helicopters performance, then we should all be ok with taking off downwind.... or what....

cmon people lets not try to make a simple thing and stir it into some complex physics crap.
Did Newton ever performe in a helicopter or test fly them? Don't think so
I think Dennis and Shawn know one or maybe even two things about helicopter aerodynamics so you should be ok with theirs explanations


There seems to be an edict which resulted in at least one so far unanswered question during this thread.
That it is folly to roll these types too quickly to starboard.

Why is this so? is this a northern hemisphere and direction of blade rotation, bit of jungle talk?

Clever stuff!! So if it where like that would it be danger to make steep right in northern hemispere but left in the southern:ugh:and ok at the equator:}
So does all french helicopters rotate in the right way in the south but wrong way in the north:confused::confused: omg this is getting worse...

This right turn problem is most likely desing related then again I don't know but "loss of translational lift" is there for sure and it will bite you in the ass....

and btw guy's isn't Nick just too busy building new Bell's to show up with good explanation

[InducedDrag]

If turning from upwind to downwind is no problem and does not affect the aerodynamics and the helicopters performance, then we should all be ok with taking off downwind


There are two problems with taking off downwind....actually three.

The first is takeoff from hover. While hovering downwind(or in any wind), the main rotor has increased efficiency especially dramatic above ETL. To takeoff downwind, you actually initially decrease the relative wind on the rotor and pass through a moment of zero wind on your way to gaining airspeed. (this calls for more power required)

Second is if the engine quits on takeoff, you will hit the ground with more relative GROUND speed.

Third and not as understood by most, climbing downwind (though a gradient which is often the case) actually continually saps energy from the helicopter and actual rate of climb as measured on the VSI will be less. As soon as you pass through the gradient (often most dramatic surface through 300 or 400 feet)your rate of climb will be identical upwind or downwind.


Plain fact is the helicopter knows no downwind or upwind. It only knows airspeed. No offence intended, but I am having a hard time believing that some of you guys who are professionals believe this downwind "voodoo". It is only in reference to the ground that the wind matters....not including gusts, gradients and wind sheer in this discussion for simplification.

[Brian Abraham]

when you climb out and turn downwind, does the rate of climb stay constant? What angle of bank are you using?
Angle of bank 30° (Ops Manual limit for passenger comfort) and yes, the ROC stays constant. Why would it not?
Try this ..fly straight and level at or below BROC turn downwind with 60°bank keep your airspeed and look at the performance of your aircraft. I bet that you have to bring the nose down to keep the airspeed where it was at the beginning. Is that a visual problem
Not a visual problem but an aircraft performance capability problem. I’d be extremely surprised if under the circumstances stated you didn’t have to drop the nose to maintain airspeed. Think of the basics. 60° angle of bank means you have doubled the “g” loading. Your R22 now weighs an effective 2,740 lbs, Jetranger 6,400 lbs, Bell 412 23,800 lbs. Remember the power required curve? Do you have the power available to provide for a doubling of the aircrafts weight? Highly unlikely, an empty 139, Puma or Blackhawk may have the capability, I don't know. To sustain the airspeed of course you then have to resort to gravity to make up the short fall in power (lower the nose).

To those still having trouble coming to grips, perhaps an illustration or two. A ram air parachute requires airspeed to remain inflated, and its BAD, BAD news should it deflate. Any problems turning up wind down wind? Absolutely none, and nothing can turn quicker than one of those babies. They are certainly affected by changes in airspeed due to gusts and care has to be taken in such conditions because they will collapse – as a BA 747 Captain found recently (lost his life).

You are in a jet at FL370 flying at 450 knots. You take a walk to the back and return to the front. Notice any difference to when you might do the same with the aircraft parked at the gate? Think of the jet as being the body of air in which you are flying and yourself as the aircraft flying in that body of air. Does the fact the body of air (jet) is moving at 450 knots influence the movement of anything (you) moving within that body? Plain as mud?
If turning from upwind to downwind is no problem and does not affect the aerodynamics and the helicopters performance, then we should all be ok with taking off downwind
You not a helicopter pilot I hope.

[Overdrive]

A ram air parachute requires airspeed to remain inflated, and its BAD, BAD news should it deflate. Any problems turning up wind down wind? Absolutely none, and nothing can turn quicker than one of those babies. They are certainly affected by changes in airspeed due to gusts and care has to be taken in such conditions because they will collapse



There won't be problems provided there is some airspeed as you say, and there usually is from below due to descending. Try an instant 180 "level" turn to downwind at 90 degree bank with a parachute and see what happens.... same effect as the gusts you mention: negative airspeed.

[Brian Abraham]

Try an instant 180 "level" turn to downwind at 90 degree bank with a parachute
Excuse me!!! I might not be the sharpest knife in the drawer but you're going to have to explain to me how a ram air makes a 180 level turn at 90° bank. You mean a braked turn or what? :confused:

[SASless]

Dear Boy.....if one is very, very, very petite....perhaps one could approach a 90 degree banked turn but I am sure it would never be a level turn (measured within the airmass it is operating) but could do so if it were in a thermal or rising column of air...heck...it could even climb with the right amount of Umph!

[Overdrive]

Quote:
A ram air parachute requires airspeed to remain inflated, and its BAD, BAD news should it deflate. Any problems turning up wind down wind? Absolutely none, and nothing can turn quicker than one of those babies. They are certainly affected by changes in airspeed due to gusts and care has to be taken in such conditions because they will collapse

There won't be problems provided there is some airspeed as you say, and there usually is from below due to descending. Try an instant 180 "level" turn to downwind at 90 degree bank with a parachute and see what happens.... same effect as the gusts you mention: negative airspeed.



Ok I should've said "theoretical" turn. I wondered what the parachute example was trying to illustrate, since you said there are no problems turning up- or downwind and then say they are certainly affected by changes in airspeed! Of course they are, but providing they keep descending then they have some "flying" speed (in parachute terms), so horizontal wind direction mostly wouldn't matter.

The issue here is that if turning sharply from upwind to downwind puts you below the airspeed for required lift for your aircraft (performance/capability), you go down at a steeper angle than you would turning upwind whilst trying to regain that speed, since you are now chasing the air you require. Downwind turns require more altitude to recover should lift be lost during/exiting the turn than upwind.

[Overdrive]

Dear Boy.....if one is very, very, very petite....perhaps one could approach a 90 degree banked turn but I am sure it would never be a level turn (measured within the airmass it is operating) but could do so if it were in a thermal or rising column of air...heck...it could even climb with the right amount of Umph!



Just to clear this up, I don't actually think that 'chutes are fully aerobatic or self-powered!

[Brian Abraham]

Overdrive - you are way, way out of your depth and display no understanding of canopy flight. Nothing wrong with that of course, but you should refrain from posting on matters of which you have no knowledge.
you said there are no problems turning up- or downwind and then say they are certainly affected by changes in airspeed
I said "affected by changes in airspeed due to gusts". Do you understand what a gust is? Do you understand how a gust might affect airspeed?

Should you desire to learn a bit about flying ram airs send me a PM with your email addy and I'll send lesson notes given to students learning advanced canopy flight. Written by one of the worlds leading educators in the subject.
it could even climb with the right amount of Umph
SAS - we had a fellow (jockey, all of 60 pounds by the look of him) jumping with us and regularly had that problem on a summer day and catching the thermals, and that was with the old round canopies.

[griffothefog]

With regards this thread, please refer to my post #42... Blah blah blah..................:ugh:

[Overdrive]

Overdrive - you are way, way out of your depth and display no understanding of canopy flight. Nothing wrong with that of course, but you should refrain from posting on matters of which you have no knowledge.



Can't say as I have much knowledge save for half a dozen jumps yonks back with ordinary-type canopies. I do know they need air going through/into the canopy though... pretty obvious.

I said "affected by changes in airspeed due to gusts". Do you understand what a gust is? Do you understand how a gust might affect airspeed?


Ok Brian, splitting hairs a bit, but of course I understand what a gust is (and what it can do to 'chute canopies). I wasn't getting at your knowledge of parachuting, but since parachutes are so different from powered, rigid aircraft (which I do know about), I was questioning the relevance of your example, and what you were trying to illustrate to "those still having trouble coming to grips"?

If you can pick holes in what I wrote in my last paragraph, go ahead, you may win 2-0! If not, let's call it 1-1.... :)

[InducedDrag]

Downwind turns require more altitude to recover should lift be lost during/exiting the turn than upwind.

This is exactly the type of stuff I am talking about.......I can not believe some of you guys are serious. Part of me believes this is still a joke but April 1st is long past.

Again.....a helicopter or parachute or airplane does not know the wind. It only knows airspeed. Ignoring gusts, gradients and wind sheer, thermals, the altitude lost in recovery will be the same. It is only the distance tracked over the ground that will be different.

I must be sounding like a broken record at this point, but I cant believe some are serious.

Now to really stir the pot a little,......... Here is the scenario. Two gliders are flying at less then 1000'agl. One makes a downwind turn and the other makes a turn into the wind. Upon turning, the pilots stall both aircraft,... if a steep wind gradient exists, the recovery on the downwind would happen with less altitude lost then the aircraft that was flying into the direction of the prevailing wind.

[Gaseous]

:ugh:

I wrote in post 24:I dont get it. The downwind elementand since then most of this thread has been devoted to discussing that.

It is clear that a large proportion of the participants in the discussion have a misunderstanding of the situation, and that confusion is not limited to the inexperienced. Despite thorough and eloquent presentation of the facts by many, this myth is not going to be busted in the minds of its supporters. It's too deeply ingrained.

A thoroughly interesting thread all the same.

[rotorrookie]

Quote:If turning from upwind to downwind is no problem and does not affect the aerodynamics and the helicopters performance, then we should all be ok with taking off downwind

You not a helicopter pilot I hope.
and Brian Abraham would you give me the plesure to explain this comment of yours......

I was compairing the effect of downwind when doing wing-over or steep turn where velocity is lost to below translational lift to takeoff.

I hope agree with me that you are better off ending into wind from wing-over or steep turn,just as you are when taking off....
see Dennis Kenyon post #22

[Overdrive]

I can not believe some of you guys are serious.


I am serious. Maintaining constant airspeed well within performance limits in a relatively gradual turn with lift to spare is one thing, and I agree with you... wind direction makes no difference. This is not the case here.

Making a very tight 180 turn at a steep bank like the helicopter that started this thread will require a huge amount of extra lift to maintain altitude, due to g loading (as Brian Abraham also said). For a time at the apex of the turn (at 90 degree bank or more), there is no vertical lift component relative to the ground, since the rotor is on its side... the aircraft wants to descend. Bear in mind also loss of forward velocity (read; airspeed), converted into centripetal force in making a turn like this.

If the aircraft is to complete the turn and maintain or regain level flight, in the absence of enough spare available power for lift, it needs more airspeed. Will it gain this more quickly with a 30kt wind up its ar*se or 30kts into its face? When exiting a steep 180 turn downwind like this it has less airspeed than the identical manouevre made into wind. It takes more time to accelerate to the required airspeed, whilst still subject to the same value of gravity. Hence it will lose more height. The altitude lost is not the same: the amount of air travelled through to regain lift is the constant.

Maybe someone else can explain it better than I have.... anyone got any crayons?

[Overdrive]

Now to really stir the pot a little,......... Here is the scenario. Two gliders are flying at less then 1000'agl. One makes a downwind turn and the other makes a turn into the wind. Upon turning, the pilots stall both aircraft,... if a steep wind gradient exists, the recovery on the downwind would happen with less altitude lost then the aircraft that was flying into the direction of the prevailing wind.


Make yer mind up. You're saying the same as I am there.... :confused:

[SASless]

Maintaining constant airspeed well within performance limits in a relatively gradual turn with lift to spare is one thing, and I agree with you... wind direction makes no difference

Can you show us the math formula for that situation please?

I was of the assumption that aircraft in level flight balanced weight/drag against Lift/thrust.

[DennisK]

Hi again,

I see that an earlier post has suggested that nothing 'constructive' by way of instruction is coming out of this discussion. True.

So may I add this to my notes. If the video of the BK 105's final manoeuvre is studied, it reveals that from the level position, Hoffman first 'rolled' right and then applied aft cyclic to climb. My display experience tells me - THAT IS THE WRONG SEQUENCE.

For a pull up manoeuvre from anything less than 100 feet, aft cyclic must be used first, then followed by cyclic roll, albeit at the higher speeds of a run-in, uncorrected disc flap back is usually sufficient to obtain the required steep 'nose-up' attitude.

What is an absolute 'no-no' is to set up a high angle of bank with insufficient collective to provide the thrust vector required to maintain height, especially at low level. I've actually watched two helicopters do this and strike the ground.

And regarding the upwind/downwind and inertia ... the situation is exactly as I outlined in the original post.

An odd thought that may help the dis-believers, (and there shouldn't be any if they hold a flying licence!) ... I was just this morning watching a recording of a Japanese Richter 7 earthquake taken from an office mounted CCTV.

The earth was shaking and reciprocating some 30 cms back & forth quite rapidly. Guess what. The PC monitor and the larger photo copiers weren't moving as the ground they sat on flapped around. I think its called inertia ... and its relative to space!

More fuel for the bon fire perhaps?

Good and safe flying to all,

Dennis K.

[griffothefog]

I give up:{ This thread has had a usefull discussion for the scientific minded, but for us ex crop sprayers it has proved nothing new... you f**ck up, you die..... As I said before, that turn was BOLD!!!!!!!!!!!!!!:=

[InducedDrag]

In my last attempt to convey something..... I will just restate the example that another posted earlier.

Think of riding on a buss. Does it take more energy to sprint to the front, stop, turn 180 and sprint back the other direction down the aisle if the buss is traveling at 100mph vs standing still in a parking lot?....

Or fly a rc helicopter in the bus. Does it fly and turn differently if the buss is moving down the road at a constant velocity (same as traveling in the wind), vs flying the rc helo while the buss is parked?..

Wind does NOT exist while flying. It can only be observed in reference to the ground. (again this is assuming no gradient, gusts, or sheer) Just as we are not effected by the fact that the earth is rotating at over 1000mph, and it is traveling in orbit around the sun at 18.5 miles per second (or 66,600mph), and the universe expanding at between 55 and 85km/s/Mpc depending on who you believe!!

Boy if we had to account for these, in addition to upwind and downwind when we turn.....flying would be even more difficult.

[FH1100 Pilot]

Griffo, I think it's just that some people are taking the idea that wind doesn't have any effect on an aircraft in a steady-state turn and then strictly (and wrongly) trying to apply that principle to the Bolkow in question and the very obvious crash that ensued. They're just confused.

[Overdrive]

Quote:
Maintaining constant airspeed well within performance limits in a relatively gradual turn with lift to spare is one thing, and I agree with you... wind direction makes no difference
Can you show us the math formula for that situation please?

I was of the assumption that aircraft in level flight balanced weight/drag against Lift/thrust.


SASless.... I mean here this type of turn can be made with no effective difference (gain/loss) in the airspeed with regard to wind direction, in answer to previous posts of the "aircraft sees no difference in wind/airspeed" point of view (and no, not supplying the formula!)


This is dragging on alright. I will say again for the final time, that during a turn like that in question, airspeed is LOST. So upwind/downwind DOES matter.


From DennisK post No. 22:-


I know that on one of the occasions I experienced the problem was when I failed to achieve the correct 'gate' speed for a 270 degree 'wing-over' following a 'toward the crowdline' level approach into a stiff breeze.

In the second half of the 270 degree heading change - the resultant tailwind significantly slowed the recapture of translation lift. The unexpected loss of immediate cyclic response and loss of height gave me more than a second of concern.

I now don't do 'into wind' display wing overs without an extra margin of 'gate' height and speed for the manoeuvre entry.



...perfectly described by someone who has been there... this is what I am saying; airspeed at the exit of the turn.


If anyone can prove to me that a turn like that in question can be made with no loss of airspeed, i.e., constant airspeed throughout the turn, I'll retract everything I've said.

[Hell pirate]

Sounds like you no what your talking about so can you give some advice on the BO105

What are the Hot and High capabilitys.

Where in the world is good to get a type rating.

Any other info much appreciated by anyone :cool:

PS Have not read the Manuel yet.

[senecashep]

I have not been able to view the video, but the problem with the BO-105 is due to the collective-to-cyclic coupling inherent in a rigid rotor system with such a high degree of effective offset. This was demonstrated to me while flying the BO-105 at WTD-61 in Manching, DE. We entered a high powered, high angle of bank turn to the right and attempted to roll left out of it. Full left cyclic, aircraft continued to roll right. The recovery consisted of a split-S with a symmetrical pull-out. All of this was planned and we ended up recovering at 1000' AGL from an entry altitude of 1500' AGL. The PIC stated to me that the German Army had lost several BO-105s due to high AOB maneuvering while NOE. Very maneuverable aircraft and quite confidence inspiring in any attitude, but in my short exposure, there are definitely some handling characteristics that demand respect.