JD-EEArm 36g was so named due to a requirement in the regulations, and its part name is directly related to the moment it was designed to handle. HazelNuts39 found the appropriate reference, and though I haven't done a search, the original discussion on the subject is spread through pages 20 ~ 30 in this thread. I believe that OE's analysis of Arm 36g is probably correct, and tail strike protection of the rudder is probably the prime reason for its existence.

mm43

mm43

Hello again. I think a discussion of Tail strike protection would be fruitful. The first consideration is to spread focal stress as the tail hits and the VS wants to keep going. With a pitch sufficient to hit tail first ~17 degrees, the Hinge axis of the rudder is roughly 34 degrees off vertical and the arm restraint would be roughly 90 degrees to the deck, so the effort seems to point to protection of the Rudder from deforming the hinge plates from a linear alignment (all seven). If the hinges deform from line, the Rudder will Bind, and not perform, an expensive fix. In this way I think the arm makes sense. OldEngineer points out the increasing danger of arm failure as the attach point decreases in size, specifically Bolt Size. The other way to express this is to say that as the attach points increase, not in mass, but in bedded area, the forces are attenuated with less structure and less risk of breakage. In arm 36g, the bolt subtracts substantial cross section from the arm, such that a failure such as we see in 447 is not surprising. Without sounding arrogant, I think rather than an arm, with its attachment vulnerability to tension, perhaps another way to address the "drop" of the Rudder relative to the VS, to protect the Rudder hinges would be to fasten plates to the spar and the Rudder Pinion, such that rather than focal (tension) strength, the area is protected by a more familiar shear solution. This would be addressed by a composite of sufficient cross section to carry the load away from the hinges, and load the Aft Spar of the VS spanwise to the Rudder Pinion(s).

It may be that the arm is after all not intended to "Balance" the shear forces of the two control surfaces under landing and tail strike events, so I have to wonder what the purpose of featuring the picture of the arm is meant to convey. At first I assumed the Picture and the numbers were included for people to make of it what they may. BEA makes no actual finding re: this arm, so does anyone have a more evolved take on the Arm issue?

Edit. Whatever people may think of my continued presence here, including those I perhaps offend regularly, my passion is genuine and my purpose is to find out the truth. I relish responses from every single person here, and could not begin to single out folks at which to direct my admiration. I am here to learn. I write no drafts, and I post without even editing for spelling and grammar. I do not even know how to drag a quote, and my prose may get brash or conceited. In person I am quite sociable, but in text, especially here, I sometimes cannot hide my feelings still. My family does much business in France, and travels regularly on Air France, a grand and enjoyable Airline to most of us, some of us like the Old Blue "Murican" legacy, no accounting for taste.

Cheers, and may the recorders be found.

bear

On the note on recorders, an interesting paper was published this year on Recovering Data and Voice Recorders Following At-Sea Crashes.

I can't link the paper, but i'm posting the abstract below. If anyone wants to read the whole thing, send me a PM and i'll email it to you.

Abstract – The international aviation safety community has
concluded that existing methods of blackbox localization and
recovery are not effective in deep ocean situations, and
occasionally not effective even in relatively shallow water when
the acoustic pinger is buried or covered in debris. The majority
of these pingers are provided by two companies, Teledyne
Benthos and Dukane, according to pre-determined form and
function, and these devices are essentially “built to spec.” The
purpose of this paper is to identify the shortcomings in the
existing, decades-old functionality and to recommend the
introduction of acoustic modem technology to provide orders of
magnitude improvement in blackbox localization and data
recovery.
Fundamental ocean physics clearly indicates that the
following conceptual changes should be considered:
1. The current pinger technology operates at nearly 40 kHz
frequency. Simply reducing the frequency to perhaps 12
kHz will substantially increase range in seawater and
even improve performance when the device is covered in
sand or debris.
2. The devices use very short sinusoidal tones (usually
called tonals) as their signals. Ocean propagation often
is highly selective in frequency due to the constructive
and destructive alignment of propagation paths – some
frequencies are supported, others are canceled.
Furthermore, it is difficult to transmit sufficient energy
into the water with these signals.Tonals are very poor
candidates for robust, reliable ocean signaling.
In addition to fundamental issues, the current system
operates by a water-activated commencement of repetitive
transmissions (pings) of these short tonals the moment the device
enters the water – even though no listening devices are present.
This is a waste of energy.
In this paper, we provide a brief overview of acoustic
propagation from the perspective of its differences with more
commonly understood radio frequency (RF) propagation. We
follow that with our suggestions for substantial changes in
operational concept, specifically arguing for wider bandwidth
waveforms with more sophisticated receiver processing.
However, given the effort to utilize more complex systems, we
recommend they be further adapted to support underwater
acoustic communications (acomms). This will provide blackbox
and crash recovery far more effectively than is now possible, and
can support data recovery when the devices themselves cannot be
recovered. In particular, acomms modems can be used in support
of long-range, accurate position estimation by either manned or
unmanned platforms. Our proposed system will be somewhat
larger than the present system, but it will significantly enhance
the ability to find a submerged black box.

HN39
Were these the statements from the interim QF72 report that gave a minus 4 degree alpha protect control authority?
If Alpha protect authority is limited, the authority may vary based on CAS.
At lower speeds, more authority would be needed. If the aircraft was actually slower than the flight control system recognized, then it might be possible to have inadequate Alpha protect authority=prompt stall entry on a Vmo/Mmo protect pitchup.
I haven't had much luck finding more information on any Alpha protect authority design logic. I might also be mis-interpreting the meaning of the QF-72 report.
However, that was a very astute call of yours pointing to an authority limitation.:ok:

"arm 36g" again!
 

As described above, the true relationship between "Arm 36g" and the rudder hingeline is revealed, and my translation was deservedly "trashed".

mm43

Location of AF447?
 

I am only 3 pages behind so sorry for the thread drift (It has been a busy week):{. Thanks for the feedback on my previous post. I have updated the FODDA drift graphs to include some of the suggestions. There are now 4 Nm (30 sec @ 480 knots) circles from the LKP. The max and min body drift area is shown about the nominal centreline. The SAR slick bifurcated angles have been projected back 20 Nm but located from what I believe is the most likely location of impact with the water. The blue line to the west is the ‘incoming’ angle of the lighter right side of the slick (54 deg off horizontal). The dark left side of the slick is made up of 3 sections basically a near vertical (85 deg) top and bottom section with the centre third at 65 deg. I have shown both these angles. The 85 deg line coincides closely with the body drift centreline. The 65 deg line is way out to the east. This may imply the most likely location is a bit further to the left than calculated by FODDA. I still have to look at the probability of other locations.
Regards
FF
http://i36.tinypic.com/10cvzpx.jpg
http://i35.tinypic.com/zna3hg.jpg

Bearfoil,
have you ever seen a video of a wing coming down after separation ?
In all cases I have seen the wing was tumbling down in a flat attitude.
Never I have seen a wing coming down LE first.
That's due to the Lift being created by the LE.
Center of Lift on a Wing is roughly Quarter Chord. CG is roughly MId- Chord. So it is longitudinally highly instable.
That's why in a flying wing plane you have specific S- shaped chords and the CG far in front of the Quarter Chord line.
Try flying with a wing only where the CG is mid Chord: Good Luck !!

So once the Wing would start falling LE first and would build sufficient Airspeed the LE would rise, thereby flattening the attitude, likely starting a rotation.
And that's exactly the behaviour you see in VidCaps where a plane lost its Wing. There was an ugly video on ysoutube of a P-68 shedding its Wing during aerobatics.

Esactly that would NOT happen !
see my explanation above.
It would hit randomly, possibly rotating but generally flat.

And that is what makes the upward bending of the lower ribs in the VS perfectly fit to the assumption of BEA that it got lost upon impact in a downward direction and not so much to a loss at altitude which would probably be more sideward than anything else.
Having said that I wouldn'i rule it out completely but I strongly tend to agree with BEA on this particular aspect.

FluidFow,

Interesting analysis !
If I continue my rough calculations and pursue my theory of high altitude stall and how it came to it, I arrive at a distance travelled by the aircraft of ~25-30nm.

1 Minute decelleration from 270kts IAS (~480 kts) to 220kts (~400kts).
Average speed: ~440kts
=> Distance travelled ~ 7.33nm.
Stall
4 Minutes decelleration from 400kts to 100kts
Average speed: ~250kts
=> Distance travelled ~16.7nm
Assuming not a linear but a more progressive deceleration (due to drag increasing progressively with increasing AoA especially after the stall).
I would rather expect the distance travelled to be closer to 30nm.

If we now assume a radius of turn of 3nm and a circle of 240°
we would have a distance travelled while circling of ~12.5nm

That would leave us 12-18nm and would bring us pretty close to the slick. Maybe 2-3nm beyond.
So I would venture to expect the crash area to be closer to the slick than in your grafic if we would pursue the logic of the above scenario.

All pure speculation though.
But the scenario can still be made consistent.

FluidFlow,

You analysis which has the likely impact to the right of the track is smack dab in the middle of the area searched extensively by the Brazilian Air Force in the several days immediately following the crash. Putting aside whether bodies were floating on the surface at that point, the other large pieces of the plane were surely there to be seen. And were not.

henra

I think you are quite wrong. The Vertical Stabilizer is NOT a wing, it is a FIN. It has ALL LIFT designed out of it. It is symmetrical in chord, and falls ballistically. The concentration of mass is low and Frontal, so the expected aspect is as I describe, it FALLS bottom down. There may be excursions in spiral, but these are slight, and eventually degrade into "0" as the Rudder Centers. The Rudder has no desire to remain deflected in ballistic trajectory, there is no impetus to sustain it. BEA is wrong if they project a conclusion based on the Fin acting as a wing.

Of course the flying wing is unstable, it has camber, and is not aerodynamically docile, as the Fin is designed to be. Come to think of it, the upward bending lower ribs solidify the opinion of entry into the water exactly as I have said, forward lower corner down, at not insignificant velocity. I think BEA have no opinion on the lower LE damage, as I do. If the VS popped out after impact, it had lost almost all of its energy, but almost certainly too much of it to end up as the significant damage expressed in the LE. It is a stretch to believe that the Fin "Rolled" over the Dorsal Fin, causing the damage to LE.

I'm out on a limb I know, I've gotten a little too explicit and may be extrapolating too heavily, but my picture of the VS portion seems clearer and more in line with Occam than BEA.

have an excellent day,

bear

edit SaturnV Some help please. If the Brazilians were searching FluidFlow's impact point in the days after the crash, why would they be expected to see anything? Drift?

SaturnV,

Maybe the Brazilian AF searched there on June 1 and 2, maybe not. Your post (#1666) contains illustrations showing significant aerial unsearched area southeast of the "Ultimo Reporte." The Brazilian Ultimo Reporte was based on a 02:14 estimated position. The BEA's LKP at 02:10 is, itself, southwest of the Ultimo Reporte...

GB

GB,

don't forget that oceanic currents in that area can be very strong, including large eddies. The currents can go in completely different directions and speeds at specific depths. Debris, depending on its weight and size would be sinking at different rates with currents at various depths affecting it very differently. Needless to say, the deeper the water, more chances of things getting "strewn around" .
The debris field on the bottom of the sea therefore cannot always be an indicator of the sequence of events...

From Deep Submergence Vehicles experience, you can end up with a rover 20-40km away where you dropped it off, and this is with their thrusters at full speed trying to compensate!

Bearfoil,
Yes if there is no Angle of Attack, it has no Lift.
BUT:
As soon as it gets minimal AoA it will start producing lift and pitching moment. Into the direction where it started building AoA.
The Flow around the round LE will start creating Lift due to Bernoulli Effect.
Take a good book on aerodynamics and you will see what I mean.
Look at aerobatics aircraft. They have fully symmetrical wings as well. And yet they fly. And they fly in the same way any other aircraft flies.
just with a little more AoA.
Or more technically:
If you look at a wing Polar of a symmetrical Profile (NACA Report 460, e.g. 0006 or 0009) you will see that the moment coefficient around the the Quarter Chord Line is constant (Null) for quite a large range of Alpha. That means the aerodynamic center is the Quarter Chord Line.
If your Cg is behind that point you get a positive moment coefficient i.e. the Wing will increasingly pitch into the direction where it started to pitch to, i.e. it is highly unstable.
Remember: Also a symmetrical Profile is a Wing !!!
It does just not produce lift at Alpha = 0.

No in all likelyhood it won't !
(See explanation above)

Edit:
It won't fall bottom first either, as the drag in that direction is much higher than LE first (High Cd of the lower side of the fin).
Only if the lower part would be very much heavier than the upper part, it could fall with the lower side first.
But I'm not aware of any reason why with an Airbus fin this should be the case.
So in a first move it would probably pitch in a dircetion where the drag is less, which would be LE in front and then the instability will take over.
Which likely will cause rotation around roughly the half chord axis
/Edit

Edit2:
The Fin is basically a Wing.
It becomes a fin by being placed so far aft behind CG and aerodnamic center of the plane itself.
/Edit2

the two bears:

current vectors over a five day period centered on June 2
http://i136.photobucket.com/albums/q...NAG-0289-1.jpg

current vectors over five day period centered on June 7
http://i136.photobucket.com/albums/q.../SNAG-0291.jpg

cumulative search grids through June 5 (circle excluded)
http://i136.photobucket.com/albums/q.../SNAG-0297.jpg

locations of recovered bodies between June 6 and 16
http://i136.photobucket.com/albums/q.../SNAG-0287.jpg

Yes, there is a small area to the SE of the last known position that was not covered by the search grids from June 1 through 5.

AF447 Search: Unified Approach
 

Not for the "why," but for the "where," I'm wondering if an effort has been launched (or should be launched) to unify the many lines of thought and theories expressed during the last year here and by BEA (including the Drift Group's findings) using some sort of Bayesian probability logic applied to the grand picture... an approach that might integrate not just the drift calcs and thier probabilities, but the ACARS clues and aircraft flight behaviors as well. Assigning all known and speculated possibilities (including wacko ideas) weighted probabilities. and then doing the esoteric calculations (way beyond my own skillset), would it be possible to zero in on a high-probability search area for a Phase 4 reflecting what is known today?

GB

henra

Excellent! Thank you, you are of course correct. I too am correct in saying that a slab of granite counter top will fly! It will, as will a brick, a cricket bat, etc.

We are in test territory, as I say, I am extrapolating, and this is a learning challenge for me. I promise not to throw the book at you, especially the equations of the Swiss Plumber. The Fin is meant to split the airstream equally, and the Captain who does that most often will please his FAs in the back as they roll their trolleys. If he goofs, he adds Rudder, which truly turns the Fin into a wing, by adding Camber.

I again disagree with your Lift thesis however. The Wing is designed to be UNstable in flight, the required correction being accomplished by the moment arm of the tail feathers. In balancing the a/c, Lift is corralled into work.

The Fin, if lost at altitude and in the condition we see in the photographs, Has monstrous drag at the bottom, with partial hoops and loose skin. The LE has second most, and the rest of the assembly for purposes of discussion has nil. Weight is at the bottom, of course, again with the LE coming in second. Sweep and Taper exaggerate the very limited overall effect on aerodynamics, especially as ALL instability disappears with loss of altitude and a gain of airstream BOXING.

The effect of the airstream at stable vertical trajectory acts to sustain the least "offensive" (to the air), ASPECT.

I do modelling as a hobby, now I'm retired, and have a hot wire and extra Foam in the shop. Shall I construct an honest model and drop it from the second story of the asylum? Wager?

all the best henra, bear

why bother ?
 

Re VS condition, isn't there info or video from the NY wake accident which would show what happens ?

I'll go with that, save some time.

bear

Bearfoil,

Adding Rudder will turn the Wing into a High Lift Wing (It's like setting Flaps).
But even without application of rudder in still air the plane would return into straight flight albeit slower and with some oscillations.

Actually the drag coefficient of the fin from LE side is the lowest of the hole thing. That's the main reason why an airfoil profile is used for the fin.
It has the lowest Cd of all shapes.

Good idea !!!
Make it from solid foam, round of the LE nicely with sanding paper and grind down the TE, so it's pointy.
Dropping from 2nd Floor upwards should give a good idea about behaviour.

I venture to guess it will tumble aound all axis and fall relatively slowly.

henra

You are getting dangerously close to an onslaught of Bernoulli banter. As a pilot, I am familiar with aerodynamics, so I will question your framing VS/Rudder as a High Lift Wing. I am on strong ground here, and must insist you be more specific. The Lift isn't Lift, strictly speaking, but can be characterised as such, for ease of understanding by those unfamiliar. If you shoot back with a defense of terms ("Lift"), I will be forced to get into why Bernoulli is for basic understanding, but is difficult to release, even for professionals, who do not pursue more complete study.

The model, if necessary, must have a fully articulating Trailing edge, ("Flap") since of course RTLU was inop, (or was it, actually?).

Hint: If you count molecules, by sheer number the work is on the high pressure side of the "Panel". Hint #2: A ruddered VS is a High "Descent" wing, and that's why using Bernoulli confuses even pilots.

I'll just keep going while you write. The "Airfoil" shape hasn't anything to do with The VS' purpose. It is an artifact of an engineering consideration having to do with strength v. drag/weight. A perfect VS has NO dimension relative to airflow, obviously. It would resemble a perfectly flat sheet of infinitely strong material with a similar panel hinged at the TE.

over to you,
small bear

GreatBear

In Post #1673 I included a screen shot taken in the Recife RCC showing that the FAB were searching from the LKP.

SaturnV

I have overlaid the FAB's Position of Corpos graphic information on the equivalent data published by the BEA. The reference points were the background Google Earth bathymetry. This leads me to reiterate that the data published by the FAB's media arm bore little or no relationship to the truth.

http://i35.tinypic.com/2ebzknp.jpg

The FIR boundary (red), the Último Reporte position (red) and TASIL position (black) from the FAB's graphic have also been included.


mm43

Bearfoil:

Without an airfoil shape the VS wouldn't create lift and therefore couldn't provide vectored force (work) upon the airframe, no?

Machaca

The VS exists to prevent the a/c from getting out of shape, period. A Rudder isn't a necessity, as you know, which means the VS needn't be so equipped, and the shape in cross section does not create an airfoil. Technically, and I insist on it, an airfoil has an asymmetric cross section, not a symmetrical one. An a/c can fly with large razor blades for wings, airfoil isn't at all necessary. Examples abound, but I've started a discussion in Tech Log, rather than here, hope to see you,

bearfoil, friend of airfoilmod

As an aeronautical engineer, I totally diagree ; I consider your definition of an "airfoil" to be quite simply wrong.
A plank can be an airfoil, a lousy one admittedly.
The F-104 has wings that are little more than razorblades, and with a symmetrical profile (with the flaps up). They're still airfoils.
There is a whole library of symmetrical NACA airfoils, and there are aircraft flying with them.
I saw you mentioned a separate subject in TechLog on the subject, so I'll go and look there before any further comment.

As to all these discussions about a detached V/S behaving even vaguely like a wing.... anybody here made up a model with about the same shape and roughly the same mass distribution and tossed it off a 10-story building? If not, why not? It would give you some real ideas about the weird and wonderful things a shape like that can do when falling through the air.

CJ

ChristiaanJ

bonjour! I used to walk by Yeager's F-104 (at the time on a pylon outside the lounge) on the way to "work", and the hard points at the tips were quite visible. The wing in cross section was thin alright, the LE had a cover on it, it was 1mm radius I believe. The wing also had a definite asymmetry, not so much in chord but it had a double curve, looking straight down the tip, it looked like a noodle. It had massive Flaps, basically planks, no airfoil. The Wing appeared to be machined out of billet, but I have seen working drawings, they are rib spar and skin, (Very thick skin relative to thickness of the wing overall). As I recall, the reason for so much anhedral was the airframe was too stable in roll, so the pilot was busy staying level. A lazy pilot of this thing was a dead pilot.

Hope to see you on t'other thread, I haven't lost my marbles, and my theory has more to do with nomenclature than one may assume at first. Oh, yeah, the rumor was that a living 104 jock had tattoos on the inner eyelids, "Speed is Life".

bearfoil,
See you on the other thread, before I go off-topic on the F-104... she who climbs like an angel, and glides like a brick....

CJ

ChristiaanJ
Hi ChristiaanJ, Yes did the experiment with a piece cut from paper small enough to not significantly distort from the Q loads. Reynolds number is way low of course, but it did just what I expected and fluttered down like a leaf. I really don't think there are any stable non-rotating modes for a single surface with relatively uniform mass distribution.

hi Machinbird

I think a slow spiral is possible bottom first, I don't consider the mass to be at all evenly distributed, with taper at the top edge, much more massive root and attached structure.

Now I must build a model, I'm thinking a meter or more in height, and rigid, meaning styrofoam, and a floppy TE. Probably more height at launch, too, to allow stability to "set" (perhaps wishful thinking.)

17:45 local. First iteration is fifteen inches tall, made of layers of heavy paper in a shape quite close to actual, visually it looks roughly similar in weight, weight distribution, and weighted to estimate structure retained by VS. No "Rudder" but the overall dimensions mimic the two panels. Dropped from twelve feet then fifteen, both times drops like a lawn dart, with a very slow spiral. Bottom down, still as a stone, no flutter of any kind. More drops and notice a peculiar thing. It falls in fidelity with the aspect I drop it with. Top down release, top down all the way. Bottom down release, bottom down all the way. Perhaps a third of a square foot in total area with a weight of 50 grams, the weight may need to decrease, there has to be something wrong with the stability I'm seeing. It is too stable. GreatBear of great animation, are you interested in some unpaid work?

bear

mm43Nonetheless, are we missing the point that "36 times the acceleration of gravity" is not a force? What is it that gets accelerated and what is the actual force vector that widget is supposed to handle?

When we know that we can address bearfoil's well meaning if persistent insistence on a specific loss of VS type scenario. One scenario I've not been mentioning lately that I can envision is quite literally a tail strike scenario as the pilots lose control, lose a lot of altitude, regain at least partial control in a dive, and are still trying to pull up when they meet the reality that they didn't have enough altitude to even lay the plane down on the water properly. The tail strike in that situation would put the tail underwater first with very heavy drag and the elevators providing sufficient force to peel the tail assembly upwards damaging the nose of the VS and breaking the attachments in the manner shown. That seems low probability. It seems to explain the particular damage to the plane, especially if the tail assembly as a whole is also torn off. It does not explain the mostly level attitude, though. What attitude of such a plane produces a tail strike while it is still on the runway? I presume a somewhat lower angle would strike the tail first before the main part of the fuselage with no landing gear down.

This all hinges, pun intended I suppose, on the meaning of the 36g, the vector of that acceleration, and the design strength of the widget. It also is important whether that part's strength is intended for tail strike protection. 36 times the acceleration of gravity is one hellacious jolt. The passengers might not survive it even if the VS did.

GreatBear for what it is worth I do remember some intensive search in that general area. It was postulated at the time on the old list that they were trying to make it to one of the two slightly inhabited virtually invisible on GoogleEarth islands in the area.

MucMuc, you're quite right on postulating eddies and the like. The other thing to consider from FluidFlow's analysis is that it does not account for the bodies probably being underwater, perhaps at a non-negligible depth, for the first few days coming up to the surface after decay had generated enough gas to bloat the bodies.

So two things are needed, the underwater current profiles and the unknowable depth to which the bodies sank. His analysis is a good line on which to search. And with the sinkage in mind that puts the likely crash site pretty close to where the slick was found, does it not?

JD-EE

At impact, I think there was very little "sinking" happening. It is virtually certain the tail left the a/c (the entire tail), and the cabin interior started to spill right away.

"10g's". Layman wise, that means a 200 pound pilot is "pulling" 10 g's, and "weighs" the equivalent of 2,000 pounds. Same for the Rudder. If it weighs 200 pounds, 36g's mean it "effectively" weighed 7200 pounds. The consideration in the rulebook is for 36g's (demonstrated) in the plane of the hinges. This obviously begs the question, why is the arm at a 38 degree bias to the "plane of the Hinges".And that is the question of the day! Rulebook notwithstanding, from an engineering consideration perspective, WTF? I still think that because at the most predicted deck angle of the a/c for a tail strike, the "36g" arm is 90 degrees to the deck, suspiciously looking like it was designed as OldEngineer would have it. I think he's right. If the Rudder does weigh 200 pounds, I consider it extremely "light" (meaning strength to weight, here), and sufficiently attached with the seven hinges (which look like they could be salvaged and re-used), to keep the Rudder in pristine condition throughout its challenges, and as I have said before, strong well in excess of the considered forces encountered in the crash, and demonstrably to the detriment of the a/c. "Lose a Rudder, keep a Fin".

bear

Henra, in support of bearfoil's concept let's consider the weight distribution a little bit more. The whole bottom of the VS is heavier than the top. Perhaps it would show a tendency to spiral nose down much like a maple leaf, even though the shape is radically different.

Building a rude and crude model out of a business card cut to a triangular shape plus some dabs of modeling clay or library paste on the leading edge and along the "bottom" of this pseudo-VS structure.

bearfoil, it appears it was specifically designed to withstand a force of 36 times the weight of the rudder parallel to the rudder's hinge line. That sounds like tail strike to me. What else would put that specific load on the widget?

That came from just a few messages earlier by mm43.

And something to consider in your tests - the rudder probably flops around pretty easily. That will upset any airfoil situation, won't it?

Bearfoil

With no hydraulics the rudder is "free"- about +/- 35 degrees. It will obviously follow any movement of the V/S and could compound a tumbling type scenario.

JD-EE

Thanks for drawing attention to my earlier post re "arm 36g". With the subjects jumping around, stuff tends to get missed.

mm43

Not long ago I posted what I think is the solution to what you propose. The Rudder is not powered, it deflects, and in doing so removes energy from the system; it has no impetus to hold anything but centered, more energy outside the system, meaning stability, not chaos. The airstream wants to bully the panel, not the reverse. There can be no "helicoptering", like a pine seed spinning slowly down in the forest, the "tips" are way out of mass, drag, and inertia to maintain that image. In fact, they are so incongruent, what I am getting with my second iteration is a slick plummet, no chaos, no "low speed". The higher I go before dropping it, the faster it drops. I'm working on getting some video, that will take time, but my sis is a CG professor, and maybe I can have a chat with her. I'd need help posting the images anyway.

Done for the day I am. All the best mm43

Bearfoil

I've read your posts on the "Bernoulli was a plumber" thread, and believe you are right when saying the rudder will center and follow. I'm reminded of the laws of nature - the blunt end always comes first, be it giving birth, the LE of a wing or the LE/base of the V/S and its child - the rudder!

mm43

JD-EE

The Hinge Line is the pivot edge of the Rudder. The Hinge Plane, is the Sweep of the Rudder. The rule is for the Plane, the Tail Strike is what is assumed by me to be the design consideration of the Arm. Someone is confused, it may well be me at this point, but I will still say that BEA got it wrong if Plane is what they meant to demonstrate. You are correct if tail strike is what you are saying also.

mm43

Noted, and thanks.

bear

Has the investigation report come out yet?

AF447 - current search status
 

The short answer is no. There have been two interim reports issued by the BEA, but without the flight data recorders the final report remains on-hold.

Published today in the Edmonton Journal is a piece attributed to the Waitt Institute, which along with the Woods Hole Oceanographic Institution were responsible for the supply/operation of two of the AUVs used in the Phase 3 search. Gives an insight into the terrain encountered and the bumps and scrapes suffered in the process, and a prognosis that the search will resume.

mm43