Cross Winds....are they a mystery?

mcrit · Post by **mcrit** » Sun Mar 04, 2007 5:24 pm

Hey Cat:
What is the minimum amount of time it should take to advance the throttle on a normally aspirated O235 from 1700 rpm to 2300rpm? Genuine question. I've got answers from 3 of my former DMs and a few of the engineers that work on them at our museum. I'd like to compare and build a consensus.
I admired the Duke, I get the idea that you did to. Why is your nose out of joint when I say he is worth emulating? I'll freely admitted I could be more like him, but I'm young, and I've time to improve.
As for my conversations about Hed; we never talked about anything that wasn't already in the public record. The fellows in question just shared their opinions as to the punishments they would have given. No breach.
Now Cat, why don't you alluded to a way to handle an extreme cross wind, I provided the broad strokes, care to fill in the details? (Genuine olive branch/invitation)

Cat Driver · Post by **Cat Driver** » Sun Mar 04, 2007 7:30 pm

" Hey Cat:

What is the minimum amount of time it should take to advance the throttle on a normally aspirated O235 from 1700 rpm to 2300rpm? Genuine question.

There is no hard and fast answer to that question because the 0235 is a very tough little engine that will normally not be damaged by agressive throttle movements.....B U T .....it is still subject to shock forces by agressive throttle handling....And the rapid changes in the explosive pressures in the cylinders are increased porportionally to throttle movement.

The best rule of thumb to use for normal throttle movements with any piston engine in any airplane is to be as smooth as possible every time you increase or decrease power. Remember regardless of how quick you apply power there is a lag in the time / performance results in the change of velocity of the airplane due to the inertia factor.

My advice is to limit the throttle movement so as the increase of thrust would not cause an engine with a constant speed prop to show surge in RPM.

The more sophisticated and powerful piston engines get the less they are able to safely absorb quick throttle movements especially geared engines with constant speed props.

Big radials will have in their handling instructions a clear caution regarding abrubt throttle movements, especially when reducing throttle. There are two very critical issues with quick throttle movements in big radials.

The most damaging is reverse bearing loads with quick power reductions coupled with cylinder choking due to shock cooling. ( remember to a lesser extent these laws of physics apply to any piston engine )

Always use the 0235 as if it is a large radial and you will then automatically operate the big ones in a correct manner.

Another comment , the slight improvement in performance time wise between smooth easy throttle movements and agressive quick movements is sweet fu.k all in importance compared to the stresses you induce on the engine by rapid movements.

I've got answers from 3 of my former DMs and a few of the engineers that work on them at our museum. I'd like to compare and build a consensus.

The more people you ask the more information you will have to be able to come to the best solution for the problem you are trying to solve. Just bear in mind the background of the person giving you the answer.

I admired the Duke, I get the idea that you did to. Why is your nose out of joint when I say he is worth emulating? I'll freely admitted I could be more like him, but I'm young, and I've time to improve.

Hell I knew Les for years and even we were the best of friends, Les was a character and every story he wrote was pure Les and there is nothing wrong with that.

If you read his stuff you will find that we were quite alike and we both admired each other for being suvivors in the risky jobs we both lived through.

I was older and had a lot more time and Les and I never really did need to compare dick lengths however when Les needed advice he often phoned me, and like wise when I needed advice I phoned him.

One thing for sure the bastard could fly an airplane right up there with the best that ever lived.

Just before he died we spent a day on his sail boat and my wife took a picture of us sitting together, when I remember Les I have that picture and I hope when my time to die comes I will have the courage my friend had...he was truly a man to admire.

As for my conversations about Hed; we never talked about anything that wasn't already in the public record. The fellows in question just shared their opinions as to the punishments they would have given. No breach.
Now Cat, why don't you alluded to a way to handle an extreme cross wind, I provided the broad strokes, care to fill in the details? (Genuine olive branch/invitation)

I wrote an article for Pprune on how to judge height that I copied here on Avcanada, you want me to sit down and write the same kind of in depth explination of how to handle extreem X/winds?

Cat Driver · Post by **Cat Driver** » Sun Mar 04, 2007 7:34 pm

delete

mcrit · Post by **mcrit** » Sun Mar 04, 2007 8:42 pm

Thanks Cat (Genuine). Everyone I talked to said pretty much the same thing about the O235, smooth and slow, I've always found a good way to get that idea across to students is to tell them to make sure any major throttle movement (take off, slow flight recovery) takes at least 5s. This seems to work well on a light a/c (ie O235 equiped a/c). No doubt this rule won't work in a higher powered engine, and students should be made aware of that.
As for the x-wind explanation, I think people would benefit from it, and I could type it in, I just got the impression that you were trying to make a point about it.

Hedley · Post by **Hedley** » Sun Mar 04, 2007 10:11 pm

Mcrit backtracked:

As for my conversations about Hed; we never talked about anything that wasn't already in the public record. The fellows in question just shared their opinions as to the punishments they would have given. No breach.

Perhaps in your opinion. Please PM me their names, and I'll start the paperwork on them.

nyco · Post by **nyco** » Mon Mar 05, 2007 8:16 am

sorry, none of my business, but mcrit and cat, you both made my day.

Shiny Side Up · Post by **Shiny Side Up** » Mon Mar 05, 2007 1:35 pm

Back on topic...

One might note that a lot of the above commments regarding the "mystery" of crosswind landings places a lot of the blame on faulty instruction or just plain incompetent instructors which to me seem hardly the only reason - one might add if the instructors being produced are incompetent, its only because the system which trains them in the first place has failed them as well.

First start at the top of how this comes to be - lets go to TC. While Cross-wind landings are part in the FTG it does not specify anywhere what limits of crosswind that is necessary to deem the student competent. No where does it mention performance to maximum demonstrated. Add to this one might note that the excersise of a specified crosswind landing (or take off for that matter, which shouldn't be ignored) is no where on the flight test report sheet. Even if it was a prospective private pilot or coomercial pilot could still pass with a mark of "2" on a scale of one to four and still end up with a licence. So to answer Cat's question of expecting every PPL holder who comes through his door to be proficient to the aircraft's max demonstrated? No! No where do we legally require it of them when we hand them a licence, PPL OR CPL. In addition I've personally had issue with TC on the matter when they come to do their inspection of my FTU, while I might defend longer training times to make sure that my students get excellent crosswind training - especially before they go solo, the inspectors made it very clear where they stood on the matter - that such extra training was not in the approved PPL syllabus. While I'm all for people getting their licences in the minimum required time - I sleep better at night knowing that the pilots I turn loose are good pilots, not just good enough pilots.

Now next we have our flight schools with the odd "5 knot maximum rule" Bad business practice? Flight school just covering their asses? Come people, we all know rules just don't appear out of thin air on someone's whim. Costs to run schools gets higher all the time - they have to protect their investments and especially their equipment - particularly when it comes to renting the stuff. Its probably a measure to stay in business, whether it be an insurance requirement or trying to work with TC to establish a safe groundwork after the last person who could "handle" the crosswind. The worst part being of this all, with prospective renters especially, is you really don't know where a pilot's skill is at with an excersise like a max demonstrated crosswind until you actually get them in one. Should every checkout involve waiting for an appropriate cross-wind day to preform it on? So what do you do? Simple: you err on the side of safety and put a 5 knot limit on operations with crosswind so IF the renter or student takes the airplane out and it increases BEYOND that limit they still have a good margin of ability to get back on the ground safely. As anyone knows in this country when it comes to the weather you generally bet on it to get worse before it gets better.

So there we have no requrements for crosswind ability, legalities and insurance comanies who would love to stifle your ability to learn how to deal with them - but lastly lets get to why it has come to this state. For this I will use a quote.

What do you do when you find yourself with a X/wind at your airport of destination that is beyond the demonstrated X/wind limits and you have no alternate left?

Of course you could land the airplane and for some of us it wouldn't be that difficult - but to put yourself in that situation is a bad choice on your part when it comes to some good ol' PDM training. If I'm always sending people out in airplanes when the wind is at the max demonstrated crosswind - what if it gets more than that? Even if we could expect people to be taught how to land an airplane at max demonstrated - we certainly couldn't expect them ALL to do it past that point. And here comes to the point of our "5 knot rule" - if you don't have a rule, there will be those out there who will push the limits as far as they can - usually until someone gets killed or a poor shiny airplane comes to grief. Which usually is the end cause of why such things become emplaced - there's has always been an idiot out there who ruins the fun for the rest of us.

What do you do when you find yourself with a X/wind at your airport of destination that is beyond the demonstrated X/wind limits and you have no alternate left?

Indeed what do you do? Its a pretty broad question. Is the wind 5 knots past the limit or ten? Twenty? Where is the limit between putting the plane on the ground safely and another TSB report.[/quote]

Cat Driver · Post by **Cat Driver** » Mon Mar 05, 2007 2:29 pm

I guess I am expecting to much in this discussion.

I am willing to learn just like everyone here and now realize that I was wrong about the signifigance of the max demonstrated X/wind.

I always thought that it was a number arrived at by the manufacturer based on the average ability of the pilots who would be flying their airplane.

Please accept my apology for having thought that pilots should be taught to the base average in aircraft peformance.

Now that I have grasped the fact that I am out of touch with flight training I would like to at least defend myself on this issue....

I had asked this question:

What do you do when you find yourself with a X/wind at your airport of destination that is beyond the demonstrated X/wind limits and you have no alternate left?

This is one of the answers I got:

Of course you could land the airplane and for some of us it wouldn't be that difficult - but to put yourself in that situation is a bad choice on your part when it comes to some good ol' PDM training.

For over forty years I have been ferrying airplanes all over the world and there were many countries where it was either very difficult or impossible to get a weather forcast never mind an accurate one.

We had the choice between leaving the airplane in a country where the owner would have lost it or continuing the ferry flight.

Even on long flights where there is weather information avaliable there is no guarantee that it will be anywhere near what the forcast is.

So once again I will ask the question in a slightly different wording.

What do you do when you arrive at an airport where the wind is beyond the demonstrated X/wind limits of your airplane and you have no other alternate and your skills level is not even good enough to land safely in a wind that is less than the demonstrated max X/wind?

Boy, I sure do get myself in some uncomfortable discussions.

So once again please accept my apologies for having used bad PDM for all those years. What the fu.k was I thinking, I should have known that not everyone is as lucky as me.

mcrit asked me to post my thoughts on how to land in a X/wind that exceeds the demonstrated max in the POH, I now realize how unprofessional that would be for me to do.

The last thing I want to do is end my career known as that guy who gave unprofessional advice to students that are being taught safely and how to use proper PDM.

Shiny Side Up · Post by **Shiny Side Up** » Mon Mar 05, 2007 4:31 pm

Now, now Cat, don't be that way...

I'm not saying that you would be using bad PDM getting yourself to the spot where you might have to make a tough cross wind landing. What I'm saying is that some pilots though have done that though and hence why we are having this discussion in the first place.

You're completely right in that every pilot should have the capability and skills to cope with normal situations - like that of a crosswind landing. The fact is though that they don't - and I'm not willing to just pile the blame on the instructors these days just being a bunch of incompetent blokes, nor should the blame lie with schools with their 5 knot crosswind rules. Both are just symptoms of a deeper problem with both the way flight training is conducted and the attitudes people have towards it.

Cat Driver · Post by **Cat Driver** » Mon Mar 05, 2007 5:53 pm

I know that shiny side.

You know that shiny side.

You also know that I posted in that tone of voice to show my disgust with the depths of mediocracy that the training industry has been dumbed down to.

What the industry needs is people willing to set up re-training businesses outside of the clutches of the moronic mindset that is TC flight training under its present management.

I fully intend to do so and hope to be able to show others that such training opportunities are needed and will pay good coin to those who have the vision and ability to offer such training.

The beauty of such a training business is you can also use homebuilt aircraft and not be victimized by TC's draconian dictates re maintenance.

I may decide to write an article on how to fly X/wind approaches and landings in winds way outside the POH guidelines and post it here.

The first problem that has to be addressed is first you must know how to accurately judge height during the flare and hold off portion of the landing....

...time is the factor that must be spot on.....

...the more severe the drift the more important timing is....especially in the hold off stage...

Homebuilt Cub · Post by **Homebuilt Cub** » Mon Mar 05, 2007 6:35 pm

Cat Driver wrote: What the industry needs is people willing to set up re-training businesses outside of the clutches of the moronic mindset that is TC flight training under its present management.

I fully intend to do so and hope to be able to show others that such training opportunities are needed and will pay good coin to those who have the vision and ability to offer such training.

The beauty of such a training business is you can also use homebuilt aircraft and not be victimized by TC's draconian dictates re maintenance.

New member here... I've read in a couple other threads that you also have a home-built cub on floats... Is yours done yet? I'm interested in getting a set of clipped wings for mine as well. Have a good day... PS your idea of a training consultant is a good one and is much needed in todays industry

Cat Driver · Post by **Cat Driver** » Mon Mar 05, 2007 7:06 pm

Hi...H.B.C.:

No I'm not finished yet...gotta sell something to get more money as my wife will not let me just keep spending money.

PM me and I'll give you some hints about building the Clip wing conversion.

The clip wing cub is a great toy if you like aerobatics.

It may not be a Pitts special but it doesen't cost a fortune to own and fly either.

xsbank · Post by **xsbank** » Mon Mar 05, 2007 7:33 pm

"max demonstrated xwind" is merely the strongest xwind they could find during the certification process. It may or may not be the strongest possible xwind that you can physically land it. Same for all the certification process that involves limits - when a certain business jet was certified it could only be operated at -35 degrees because that's the coldest they could find during the C. process. That's changed now, and seems silly when you can get -65 at altitude, but you weren't using gear and brakes etc. up there.

Strongest crosswind I can recall was a 40-45 knot direct x-wind in a Tracker, the first week I got checked out in it. We flew in and out all day and it never got less. Fun a/c, the only one I ever heard of that you could stall the rudder - you'd be pushing like a bugger and suddenly the pedal would go to the floor and you needed both legs to unstall it. Exciting moments, they were.

I used to make all my clients do stronger and stronger xwind landings in the sim during their type, 'til they couldn't do an 'acceptable' landing anymore - record then was 50 knots, well above 'demonstrated.'

Sounds like nobody knows what the rudder is for anymore.....

Cat Driver · Post by **Cat Driver** » Mon Mar 05, 2007 7:58 pm

Yup, xsbank x/winds are nothing more than just another landing.

The amount of x/wind an airplane can be landed in is not even limited by full control deflections.

If you practice enough you can exceed the full control deflection control limit by a fair margin..the secret is practice.

" Fun a/c, the only one I ever heard of that you could stall the rudder - you'd be pushing like a bugger and suddenly the pedal would go to the floor and you needed both legs to unstall it. Exciting moments, they were. "

The Catalina with a Davis Tail conversion such as on the Super Cat will aerodynamic lock also, the only way to overcome the aerodynamic pressuers of a locked rudder in the Cat is to stall it...then two pilots can overcome the force and regain normal rudder control.

But it is very rare for this to happen as it takes cross controlled flight with a nose down pitch to aerodanamically overcenter the rudder...
...Don't ask me what I was doing when it happened to me.

mcrit · Post by **mcrit** » Mon Mar 05, 2007 8:12 pm

Hi XS, who were you flying trackers for.

l_reason · Post by **l_reason** » Mon Mar 05, 2007 9:21 pm

Cat, Hedley and other seasoned pro’s. I would love to here a few pointers on how to better land a light (1400lb) tail dragger in winds that are higher then the max demonstrated. I have landed in 15-18 direct x-wind I just cant get comfortable with feeling just after touchdown as speed decays just a few knots below the stall. Between the time that my rudder has decent authority and the brakes/tailwheel becoming effective enough to take over control. I have tried landing in strong x-winds both 2 and 3 point but the there always seems to be a few moments when I don’t have enough control. I’d like to feel more comfortable in that kind of wind and leave the nervous feelings for when I get stuck in 25+.

xsbank · Post by **xsbank** » Mon Mar 05, 2007 11:38 pm

mcrit, I'd have to kill ya'...

trey kule · Post by **trey kule** » Tue Mar 06, 2007 12:42 pm

Cat wrote:
But be prepared to get a snow job as twice I presented living witnesses to exactly the same type of degrading comments by TC officials to my clients.

Well, it seems you are right Cat.
Edited:
I got my information wrong. It seems that they were so awfully busy that they did not find his inquiry important enough to reply. When I called to find out what happened there was a little confusion about which issue I was asking . End Edit

I dont think there is much more I can do unless Mcrit wants to share the names. And he seems comfortable making unseemly remarks about people and then hiding.

trey kule · Post by **trey kule** » Tue Mar 06, 2007 12:57 pm

XS bank wrote:

mcrit, I'd have to kill ya'...

Deal. Tell him and then....ah, you know..get to the killing part

I am a little confused about some of the definitions of Max. demonstrated crosswind component as listed in an a/c's POH.
I have a terrible cold today, but if someone would actually take the time to look this up on the FAA's website and post it we might all be able to deal with this better.

I think you will find, that the max demonstrated refers to no unusal control imputs and is not a limitation as such. It is entirely possible, and not particularily difficult to land most planes when this component is exceeded.

I still dont get what all the fuss is about x-wind landings.

Doc · Post by **Doc** » Tue Mar 06, 2007 1:47 pm

Wondering how many times you've lined it up on final, and said, "not today, thanks.." I've done it a couple of times.

trey kule · Post by **trey kule** » Tue Mar 06, 2007 2:00 pm

Doc wrote:
Wondering how many times you've lined it up on final, and said, "not today, thanks.." I've done it a couple of times.

The company I work for now, realizing pilots inabilities to judge their own ability and the vastness of their egos, sets our X-wind limits in stone.
If the advisory wind is over those limits, we are not even allowed to attempt the landing. But yes in the past, I can remember lining up on a runway and dropping a wing and then running out of rudder to keep it straight....time to go home. What is even more clear to me is the times when I actually got it in that were based 98% on luck and 2% on skill. Now that think about it, it is truely amazing that I have never bent anything.

I think the trick is to not get stressed up about them. Just take some of those hickory chips you use for the barbeque, soak them in rum. Squeeze the rum out and add lime juice to it. Then drink and all will be well.
BTW: We call it a Hickory Daquiri Doc.

Shiny Side Up · Post by **Shiny Side Up** » Tue Mar 06, 2007 2:13 pm

Cat Driver wrote: You also know that I posted in that tone of voice to show my disgust with the depths of mediocracy that the training industry has been dumbed down to.

What the industry needs is people willing to set up re-training businesses outside of the clutches of the moronic mindset that is TC flight training under its present management.

I wouldn't really put the blame all on TC either Cat as much as we would like to. The moronic mindset that TC regulates us with is handed down from the government that runs them, which of course we elect...

And there it is: That's what your average Canadian is content with, lots of pomp and circumstance which results in a mediocre training process. To your average new pilot out there its more important to fly a shiny new airplane and your instructor to wear a uniform, to get a licence for a bargain price, and to do it all within a minimum time. Take a look at how people drive their cars these days: everyone will pay for a "safer" vehicle, but no one wants to spend the time to learn better driving skills.

Now I might be an idealist, but I still believe that good flight training can be delivered, even in spite of and within the present management of TC. (I'll give you a second to stop laughing) But it take two to play the game of flight training, the trainer and the trainee. In the end, if flight training is dumbed down, both trainers and trainees have beeen willing participants in it.

I fully intend to do so and hope to be able to show others that such training opportunities are needed and will pay good coin to those who have the vision and ability to offer such training.

Then lets hope we have people who are wise enough out there to take you up on your offer. Unfortunately they will probably balk when it comes to the "good coin" part of it. As the system is, right now we have it so the system is only required to turn out 60% proficient pilots (or 70% if you want to get paid to do it) and that's the way people want it. While we might strive to make them as close to 100% pilots - those getting into the system have to want that, and most importantly be willing to pay the cost for it. Lets face it, just like everyone isn't cut out to be an astronaut, not everyone has the ability (or in most cases the drive) to be that ideal 45hr perfect PPL student.

Its only going to get worse too, I mean if we go back to our beyond limits crosswind situation - there's some out there already who's answer would be "pull the chute". To them the cost of a BRS installation is money better spent than a few extra hours of flight training.

I may decide to write an article on how to fly X/wind approaches and landings in winds way outside the POH guidelines and post it here.

I would caution against it, if only so a TSB investigation doesn't begin with "Cat Driver said..."

Not that you would give any faulty advice, but that as fool-proof as any technique you might explain, you can't possibly account for the fools out there who might decide to apply it...

Cat Driver · Post by **Cat Driver** » Tue Mar 06, 2007 4:12 pm

Blus Side:

You are correct, if I were to post an article explaining how to fly at the outside envelope of an airplane I would putting myself in danger of it coming back to bite me.

Have you noticed I did not post it?

My comment about making good coin teaching was not directed at ab-initio training it was concerning skills upgrading of licensed pilots using homebuilt aircraft and no need for an OC.

Things have really changed for me in the last few days.

I will be going back to work this summer as one of my former clients has something for me to do in Africa....

...there is no whore like an old whore they say so I agreed to do one more contract.....

...this one has some potential and maybe when I return to Canada I may be better off in more ways than one....

It looks like my summer on the west coast may be interupted for some time.

My wife was quite calm about this latest turn of events as she just shrugged her shoulders and said I told you they would not let you quit........

But she likes Africa so I cut a deal with my employer and she will be spending some time in Africa once again as a tourist while I work.

She made a real interesting comment today, she said can't you see the difference between you and Merlin Preuss and his ilk, they live in caves insulated from the world and they would never be asked to do the things you get to do......

She has a point.

Anyhow I won't be leaving until mid summer so I'll be here for some time yet.