HazelNuts39

Thanks RRR;

BTW, .04 kWh per hour amounts to 40 W.

Machinbird

You gentlemen are overlooking an important mode of melting the ice/snow inside the probe.
Infrared radiation.
Some initial reading on the subject tells me that we are lining the interior of the probes with the wrong substance. From a Nippon Steel technical report on infrared spectroscopy, this telling observation: http://www.nsc.co.jp/en/tech/report/pdf/n10014.pdf
I can think of geometries that would promote both modes of melting (conduction and radiation) and which would promote development of open channels through an ice mass.
Seems to me that pitot tube heating design is stuck in the 1930's.

Machinbird

OK,
I've had too many cups of coffee today, but another thought occurs.

To get more power into a pitot tube quickly, you could couple it up to a waveguide and 'nuke' it the same way we heat water bearing items up in a microwave. Those guys designing aircraft pitot tubes really have been stuck in the dark ages. Stick with what grand daddy always used must be their motto.

Lyman

Why Stainless Steel anyway? Delrin, Ceramica, Teflon, etc. Why such a sharp entry? I must be a cup behind, Radar Heating occurred to me as well.

A very thin analogue to the current problem is the Shuttle tiles. A very heat averse medium Isolates heat from the inner surface. It is as if the current design fosters the retention of the snowpack.

awblain

I'm not sure powerful IR or microwave heating of the air within the pitot tube is necessarily desirable.

I am reasonably sure that you want to minimize changes to the temperature of the air in the pitot probe as compared with the air next to the static probe.

Lyman

Technically, is the 'air' being heated? There is no flow whilst the plug/ice is being expelled, so either a constant current, or a transient one, same as current design? The Steel is maintained at a high heat (Don't Touch!) so would the downside be unmitigable? Dunno. The probe currently requires a fair current, and precise Temp control in flight is not a design consideration, is it? Also, Dunno.

bubbers44

Subject: Test Pilot Burt Rutan, on Airbus



Passed on by an experienced guy who worked for Lockheed and then the FAA for years. He absolutely refuses to fly on any Airbus because of their French designed fly by wire system.


Bill, These machines are mfg in Touloius, France and have certification by CAA and ICAO over there before they go for our FAA certification. It depends a lot on direction from the white house and congress as to what the FAA does when it comes to dealing with foreign governments. Some times the FAA doesn't have a whole hell of a lot to say about the end result when pressured by the State Dept on some political issue. I think the FAA core knows all about the Airbus systems that are so radically different than any we have here. The computer nerd systems on the Airbus have caused numerous crashes over many years since their inception but never enough of them at one time to get people up in arms.


Airbus is ALMOST as good as Boeing in hiding the real cause of crashes. I remember about 20 years ago when the A319 was being introduced to India. The pilot thought he had control during a landing BUT the nerds system took over on approach, throttled the engines back to idle, and the bird plopped down in the pine trees and exploded about 1/4 mile from the end of the runway. OF COURSE--Airbus found that it was pilot error since neither he nor the copilot survived. Twenty years later the same nerd systems on a A320 put Capt. Sully in the Hudson. The nerds sensors on the engines determined that the bird strike was cause for shutting down the engines and it shut down both engines and the pilot had no control to restart them. Actually the strike did nothing more than smear some goose guts over an engine PTO probe and their was NO reason to shut down the engines. If this had been a Boeing, Sully could have used the engines to make a safe landing.


The Air France 447 was another nerd screw-up in using JOY sticks to fly a huge airliner--the A330 is a huge bird!!
What makes this incident so sad is that the exact thing happened to an A330 in France five or six years ago during a demo flight by their chief test pilot. The accident was the basic responsiblity of the chief test pilot as he allowed a customer pilot (with very little flight time) to make the take -off to show him how simple it was!! On take-off the customer pilot pulled back too much on the JOY stick, and before the chief could take over, stalled, crashed and burned right in front of the control tower. Just like 447 the chief couldn't see what position the copilot JOY stick was in, as it was covered by his hand, just as the Capt on 447 couldn't see what control inputs were being made when he entered the cockpit at 18,000 feet on the way down to the water. If it had been a Boeing he could have seen the copilot pulling back on the control yoke causing the the stall. And to further the confusion in the cockpit--when the right JOY stick is moved, the left JOY stick doesn't move with it. When one moves either control yoke on a Boeing the other control yoke responds with the same movement--not so with the nerds system!!


Bill,
the only thing we can do at this point is stay the hell off Airbus equipment!!

Jim,
Where’s the FAA in all this ??

A33Zab

Read good information and valuable discussion on PPruNe, but also a lot of rubbish......this post is beyond the last category.

bubbers44

Somewhere in Europe obviously. I think this ruffles a lot of feathers but Dick Ruttan is a genius with what he has accomplished in aviation and I agree with his comments. Not seeing what your FO is doing on the side stick kept me out of the air bus. That big yoke in front of you tells you when it is time to take over. It rarely happens but sometimes you need to know what the other guy is doing. In the Airbus it is difficult with the side stick from what I have been told. I chose never to fly one.

Machinbird

Bubbers, Not up to your usual professional standards to publish something like that "article" of unknown pedigree.

For those wondering about the effects of "heating" the air, inside the pitot tube, remember that it should not be trapped if we can keep the tube from getting plugged in the first place, and is always flowing through the tube to the drain ports at a relatively low speed. There is no way to change the pressure in the tube then from heating the gas inside the tube. (I suppose if you got really ridiculous with heating you could start looking at ramjet theory). The idea is to be able to rapidly apply energy to the internal volume of the pitot tube, and if the thing begins to fill with solid water, to rapidly convert said solid water to a liquid so that it may be purged from the probe vent holes with dispatch. To do this reliably requires sensing systems and a better means of applying energy than is presently being used.

The absorption of either infrared energy or microwave energy by the atmosphere is miniscule unless you then throw in water in some form or other. There are some relatively narrow absorption bands in the infrared spectrum from molecular dynamics.

bubbers44

I don't understand the pitot heat and my Dick Ruttan story having anything to do with what we are talking about. He flew around the world non stop and made a world record. He put a man in space without NASA. He has this opinion about Airbus and I agree with him. That is all.

Lyman

bubbers

I think you may be confusing the two brothers. Dick flew non-stop around the Globe, Burt launched a human into space w/o the 'help' of NASA.

I don't trust Dick Rutan. Burt? He is the genius. Which one has the HO for Airbus? I have neighbors on either side here in the retirehood. Both flew the Airbus, and both love it. That's all I need to know.

PJ2

bubbers44;

Re, "Bill,
the only thing we can do at this point is stay the hell off Airbus equipment!!"

Well, if that's from an aviation professional I don't care what they've done, that's just plain stupid and embarassing. It's prejudice all the way down because the author clearly knows nothing about the Airbus, doesn't want to know but condemns anyway. The stories prove that anything can be twisted to support prejudice if that's all one's agenda is.

You've made it abundantly clear over the years that you don't like, don't trust, and don't know the design. That is sufficient to make your point; there is no cause to re-argue the case each time something comes up regarding the AB discussion. It's boring because it doesn't advance discussion and doesn't contribute to others' knowledge or understanding.

bubbers44

OK, that is how I feel about AB. Sorry.

PJ2

bubbers44, no problem. My whole point is you don't need to say you're sorry...I'm offering feedback that your views are well and thoroughly understood. I'm not trying to change your mind. I don't need you to "believe in Airbus". But it would be pleasant and interesting to advance discussions on points of understanding, most of which don't involve the Airbus.

If a Rutan or an FAA guy said those things that's really disappointing...I would have expected more comprehension and thought, but there it is and we move on.

Mr Optimistic

Bit puzzled about pitot tubes: if these are a worry why not just make them physically bigger. Would take more to block them and the thermal inertia (mass increasing with l cubed, surface area with l squared ) would increase, smoothing temperature changes.

StainesFS

As my user name suggests, I am not a pilot, professional or otherwise, and have no axe to grind in the A v B debate except to point out that, if we are to have this debate, the views entailed need to be supported by facts. (I am a scientist by training). The mysterious "Bill" quoted in Bubbers' post uses "facts" which are not supported by the relevant accident reports. In some instances, he is just wrong in his assertions and, in others, he seems to stretch investigator's comments to suit his agenda.

The A319 crash about 20 years ago is, I presume, a reference to Indian Airlines 605 (actually an A320 but that is irrelevant). The report is sparse in detail on the cause of the excessive descent rate, but "Bill" apparently knows more. It mentions pilot error with the flight crew not recognising that the aeroplane was in open descent rather than "approach mode". Much of the criticism of the Airbus philosophy at the time came from the French pilots' union who were unhappy about the loss of the FE in the two person flight deck. This philosophy has, of course, long since been adopted by Boeing also.

The A330 test flight accident was attributed to several causes not just the excessive pulling back on the side stick by the FO. He, incidentally. was not a customer (although Alitalia personnel were on board but not as crew) but as an Air Inter pilot on attachment to the Airbus training arm.

"Bill" seems to think that the engines on the A320 involved in the Hudson ditching were basically intact and were shut down due to, in effect, a computer reacting to a damaged sensor. However a cursory reading of the FAA investigation report reveals details of much more severe physical damage to both engines resulting from impact by particularly large birds. In the interest of balance, the report did state that the successful ditching was due, in part, to the Airbus FBW system.

My own view is that unless or until accident statistics show a significant difference between A and B (one way or another) in accident rates then it becomes a matter of personal pilot preference, which is their right. At the moment, I do not believe that the statistics show any such difference. In the context of a complex investigation into a tragic incident, such views as are declared by "Bill" should be ignored as not being fact-based. They might possibly be seen as part of the continuing propaganda war (conducted by both sides) between A and B in the furtherence of sales. Nothing wrong with that but in its rightful context.

PJ2

StainesFS;

Re, "...if we are to have this debate, the views entailed need to be supported by facts."

Not to beat a really dead horse, but yes, that was the point I was also trying to make, thanks.

I know these accidents; none of these accidents occurred in the way "Bill" described, so it is just more of the same boring A vs. B propaganda. I'm surprised that the Habsheim accident wasn't trotted out again.

Apropos your comments regarding statistics you will appreciate the meaning behind the following, from Boeing. Compare equivalent A vs. B types in the numbers:

Statistical Summary of Commercial Jet Airplane Accidents, Worldwide, 1959 - 2010.

What such populist myths such as those posted above perpetuate and even legitimize is an institutionalized lack of understanding of what really happened in these accidents. That is not how flight safety and investigative work is done nor is it how training and learning from others in this business is done. "Bill", who remains unidentified and mysterious, should come to PPrUne and join this thread to defend his views and perhaps learn a bit himself. There are some here who critique the airplane thoroughly but they know it and fly it. Vive le débat!

Perhaps also of some interest may be Psychologist Daniel Kahneman's book, Thinking, Fast and Slow which in part discusses how we make up our beliefs, assess/decide upon risk using intuitive and/or rational thought. Last November Vanity Fair ran an article which may be of indirect interest to some: The Quiz Daniel Kahneman Wants You to Fail

PJ2

HazelNuts39

Neither CAA nor ICAO have any involvement in the certification of Airbus products.

Algy

Indian Airlines accident analysis in Flight International.