Ultralight Crash

[quote="Dave Calkins
Question: Why is it so impossible to believe that how you manipulate that heavy ag-plane through a turn (upwind or downwind) is accomplished through your eyes, butt, hands, and feet?

DAVE[/quote]

Well Dave let me answer a question with a question and I mean no offense. Why is so impossible for you to believe there is something you don't know?

And for the record I'm not "hot under the collar" just frustrated.

This conversation is like a Doctor telling his patient that his illness is "all in his head" because he can't diagnose the problem and the next day the patient dies.

Not getting arrogant.

Dave Calkins,
I am sorry if my numerical statement of turning experience seemed boastful to you. It was not meant that way at all. Due to the large spectrum of differing flying experience here and humans natural tendency to only see their own life experiences as truth I felt it pertinent to put the number of turns accumulated by us into perspective for those that have never thought about it. You have to admit that the average GA pilot will make very few turns in his/her career and even fewer down low and on the edge.
Example; I know a guy that flies to work twice a week about 60 miles. More current than most pilots I know of. However due to the prevailing winds of our area 90% of his flights per year are a takeoff straight into the wind, straight at his destination, followed by a straight in to the destination runway. And because of the 180 degree wind switch that occurs during the day while he works a simple reverse going home in the evening. So he flies about two hours per week about 45 weeks a year just doing that and makes NO turns. Yeah he's a pilot, he's current, he's been doing it for over 15 years, but what the hell would he know about turning?
To me this discussion isn't about hours or years flying it's about turning. And I don't think that most GA guys think about it in true terms of what we do even if they've seen us work. We don't just turn in the pattern, or if we happen to see some game as we meander past at 500 feet, or if we run into some weather. It is a necessity of our job over and over and over.
So call it my insecurity but I felt it necessary to give my personal experience at this specific task within flying so people would know from where I make my opinion. By the way it was 475,000 not 40,000. Ballpark. And I'm not old at this crap either. Not chest beating just clarifying reality and if one respects a pilot's opinion with 30,000 hours more than a pilot with 500 hours then why not in these terms?
Another little observation of my little high school dropout brain is that Galileo and Newton didn't have experience making downwind turns day in and day out in varying conditions. The old "it looks good on paper"?
I still want to get with the ag pilot that thinks downwind is no different than up when a rapid heading change is made. They'd be the first of my counterparts that I know of thinking that way and I'd be very interested in his perspective and how he formed it IN THE COCKPIT WHILE WORKING not on paper.
Still haven't had anyone comment on my comment of flying a helicopter crosswind at 25 and turning briskly downwind to run with a 15 mph wind and losing translational lift. Why? The rotor disk is a wing too.

Re: pumps

ag-pilot said:

Aalexander, What do you need to know? I would love to have someone tell me why this happens. The pump is driven by a fan, The pump is only used for application of chemical. It does not matter who make the pump or the fan or the airplane for that matter they all do the same thing and that is you will see a bit more pressure down wind. If your ground speed is 20mph different up-down wind you will see 2-5 psi more downwind every time in every spray plane that I have flown with a wind driven pump. My guess is that wind driven alternators or anything else would also run faster downwind. Come-on guys dazzle me!!!
Dave

Click to expand...

Sorry, no dazzling here. Like I said, it's an interesting effect, and as has been mentioned, on the face of it seems opposite to the effect we're discussing ie: if you lose air over your wings downwind, then you'd expect the wind on the turbine to be less and thus the pressure to be less whne headed downwind. By more information, I mean information that you'd only get if you dedicated a bunch of time and money to figuring it out, things, information like: what fan RPM difference is required to make the 5 psi increase in pressure, what effective airflow velocity difference would it take to create that RPM difference. Do you get the same effect if the turbine is mounted under the wing instead of under the fuselage in the prop blast, do you get the same effect if the turbine is on top of the fuselage, or on top of the vertical fin. Do you get the same effect at 20 ft AGL as you get at 3 ft AGL? At 50 ft?

It would be really interesting if you and I had the time and resources to get together and try to find the answer, unfortunately, I'm guessing that you are like me and have a job and limited funds. SO it will have to remain an mystery.

The best I can do is throw this out there for speculation: Perhaps it has to do with the wind gradient; the wind speed at 2" AGL is going to be less than the wind speed at 50 ft AGL. when you're flying downwind, the turbine is in slower moving air (relative to the ground) than the rest of the plane (except the landing gear) so the plane, effectively is getting more of a tailwind. So the plane with a tailwind and thus higher groundspeed is dragging the turbine though air that is moving "downwind" as much, so the turbine "sees" a higher effective airspeed than does the upper parts of the airplane. This same effect would be reversed on an upwind swath, so that the turbine would "see" a lower effective airspeed, and the difference between the upwind swaths and downwind swaths would become large enough to be noticeable.

Again, I'm not saying this *is* what is happening. I have no idea whether or not the wind gradients down low are great enough over a few feet of height to cause this, I'm just tossing this out for discussion.

There may also be some interplay with the propwash and the ground, sometime those things behave in ways one doesn't expect.

Widebody said:

Wait a minute aalexander.... Maybe I should have been clearer in my
posts but lets get it clear now.

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Widebody,

I have to apologize, I was thinking of another poster (Brokenbone) when I inadvertently typed your screenname. Sorry for the confusion, and for the record, I didn't believe that you and I disagreed on the 10,000 AGL smooth wind situation, just a case of mixing up screen names.

And no, I don't think that you (or any of the other ag-pilots for that matter) are a dumb-ass. To restate my previous post, I don't know what it is you're seeing. I don't have an explanation for it. My position is only that it is not a result of the mere fact of turning down wind, but possibly a result of the interaction of the wind and the ground (if that makes sense)

Again, sorry for seeming to put words in your mouth, I did not intend that.

Taledrger said:

This conversation is like a Doctor telling his patient that his illness is "all in his head" because he can't diagnose the problem and the next day the patient dies.

Click to expand...

To go along with that analogy, people can die of psychosomatic illnesses. In places like Haiti, where people really deeply and sincerely believe in voodoo, it is not unheard of for a perfectly healthy person to get sick and die after finding that someone has put a death curse on them. The mind is a very powerful thing.

That is not to be interpreted as me saying it's all in your head, though.

Re: Not getting arrogant.

lowflyin'G3 said:

"....... just clarifying reality and if one respects a pilot's opinion with 30,000 hours more than a pilot with 500 hours....."

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I don't.

This is a bit of a tangent, but I do not automatically assign more weight to someone's arguments based on the thickness of their logbooks. (And mine is plenty thick, thank you, so don't dismiss my comments as some low timer's inexperienced meanderings)

A while back, on another forum, I saw a fairly low time flight instructor tell a much more experienced pilot (who disagreed) that you can increase the engine out glide distance in a single engine airplane by pulling the prop control to the low RPM stop. whole bunch of fairly high time pilots came along to tell him that he was just a low timer and therefore knew nothing and should just shut up and listen to his more experienced superiors. The thing is, the low timer was absolutely correct. During the course of the discussion I actually tested the theory in my own airplane under repeated, fairly well controlled conditions and found that in a 180 on EDO 2870's with an 88" prop, you could increase your glide distance by about 20%. Faced with that information, not only wouldn't the high timers back down, but one actually told me that my experiment had no relevance to a Bonanza (the aircraft in question). He was unable to explain why it wouldn't work in a Bonanza, just that it couldn't. It was an embarrassing display, and the main issue really was that a low time pilot had the impertinence to (correctly) point out that a higher time pilot was incorrect. I have seen that pattern time and time again in hangar flying and internet discussions, this is just one that comes to mind readily.

That said, I agree that your expereince with low altitude turns does have relevence to this discussion, just saying that a thicker logbook doesn't, in general, make one infallible.,

tempdoug said:

This may sound dumb, but ive tried many times to read all this and I cant figure out exactly what everyone is trying to figure out. Sometimes i think im understanding, then all of a sudden its beyond me. Which is easy. Please no comments. But could someone simplify it down to a sentence or two? Ive always thought of air like water. If a boat is pulling a skier 25 mph gps speed up stream where he can barely stay on top of the river, then turns and goes down stream 25 mph gps speed, wont the skier sink? thanks doug see ya Sunday in Botno, Brad?

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In that situation exactly as you've described, yes the skier would sink. However to achieve 25 mph gps upstream and 25 mph gps downstream, the speed in the water would have to be much less downstream, and that would require a lot less power going downstream.

Let's say that the river is flowing at 4 mph, so using your numbers, if the boat is going 25 mph (gps) when upstream, then the boat's water speed is 29 mph (29 mph across the water - 4 mph current = 25 mph relative to the shore) no if that same boat, pulling that same skier made a downstream run, at the same power setting, the speed across the water would be the same 29 mph, but the GPS speed would be 33 mph (29 mph across the water *plus* the 4 mph current, and the skier would still stay up, because the only thing that matters to the skier is the 29 mph across the water. the skier doesn't care how fast the shore is whizzing by (unless of course he's going to hit it)

Broknbone said:

Anyway, aalexander, I emailed a physics professor at our local community college and he wrote me back. He seems interested in reviewing the debate. I wrote him back with an explanation of the debate and sent a link to this string so that he could read it himself. I'll post what he says. I'll man up and admit it if I'm wrong. I'll bet you a pint of Humpy's Sockey Red IPA, however.

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OK

You might send him the link to one of my other posts in another thread. I don't know if you followed that the thread split briefly, but my best description of how I see the situation is actually posted on another thread, and that is the one that I think would be clearest to someone with a physics background. It's on this thread:

http://www.supercub.org/phpbb2/viewtopic.php?t=16616&start=30

Yikes!.

G3 sorry! I used that '40,000 turns' in a general way not meaning specifically you, nor did I remember who wrote it.

Sorry to offend you, and not meant that way.

I don't have time right now, and did not read all the posts since my last visit here, but will go through them when I return tomorrow.

Again, I didn't mean to be uncool to anyone. And am trying to learn what I can here.

Also, again, I am curious what the answer to my question about what puts an ag-turn together?

Dave.

Delete duplicate - sorry - -

Funny how some fellers totally disrespect and disregard the so-called 'book knowledge' generated by those guys Galileo and Newton, whose names are remembered four centuries after their work. Men whose ideas were so painstakingly and perfectly crafted as to be substantianted without exception by nearly 400 years of the most meticulous and skeptical experimental testing, and whose conclusions remain the foundation of the most modern mechanical systems analyses.

400 YEARS of substantiation for those guys. Yet some fellers in this thread, who choose to grasp at straws for their position (not their ideas), decide to gleefully discount those intellectual giants because they lacked sufficient PIC hours. Then the same fellers proceed to whine about others' purported disregard for their vast experience - maybe a few thousand HOURS of anecdotal evidence from which they prefer to draw absolute conclusions. I'm not talking about S2D and Ag-Pilot and those who write similarly, I'm talking about a couple others.

I don't recall having heard anybody diss on what these ag guys are saying - I have only heard folks try to explain. (don't beat up on me too much for that sentence - I realize that I may be remembering wrong). But I sure have heard a few fellows make the snarkiest (I LIKE that relatively new word - it just SOUNDS right!!) of remarks regarding the 'book' ideas some of us have offered.

To paraphrase Kathleen Parker, the syndicated columnist, those who are unwilling to listen and think and modify or add to their ideas will forever remain afflicted with 'selective ignorance'.

Several of us on both sides of this discussion have consistently tried to remain polite, and have posed or at least rationally discussed possible mechanisms that could reconcile the differences of opinion and observations presented here. I am one of those who have spent hours thinking about the situation because it's interesting - then formulating and typing lay and technical explanations of accepted mechanical knowledge, and proposing possible explanations for differences.

I am a teacher, so I deal daily with kids who do not want to learn (in the case of kids, they tend to either think it's irrelevant, or more commonly, they think they can't). But I sure hate to see closed-mindedness among us intelligent adults. I think I'm still being polite, but this time I am taking the liberty of stating rather directly what is on my mind right now about the PROCESS of this discussion. Can we PLEASE discuss this rationally, with integrity and respect, and with the intent to figure out what, EXACTLY, is happening, and WHY? And with a willingness to modify our thinking? I have had some excellent, thought-provoking email interchanges with TonyRV, the physicist who posted early on. We have been sharing and trading information and analytical perspectives - agreeing, and disagreeing, and each willing to modify our own thinking - not trying to beat each other down, but to figure the phenomena out. Can't the rest of us follow suit on this thread??

Those who merely scoff at my and others' "book-learning" (only a couple of folks are doing that) don't bother me much because I consider the source, but nonetheless fellows, guess what? I've been around a little in my 60-some years. I have a couple of degrees, and a couple of broken bones too. Got 'em working. I've wrecked (and fixed) a couple planes in the boonies of Alaska, and I've successfully operated out of some places there where none of my acquaintances would go. Bragging? Good grief, no. Just pointing out that I'm aware of what stick and rudder and throttle are about. Anyway, I know exactly why each wreck happened (one was from gusting. And of course poor judgment was mixed in). I can explain them with mathematical models as well as with plain English, and I can avoid them in the future. I teach math and science, and in the summer I make hay and log with teams of draft horses - my point? I take pride in applying 'book-learning' in the same places as my dirty hands. Engaging head and hands together potentiates the ultimate synergy of human endeavor.

So don't diss on the books. They have accumulated knowledge to offer. Can we correctly apply that knowledge? That is the challenge. Knowledge is not generated by repeating a mantra - it comes from independent thinking. Let's get to thinking more, and reciting our favored chant less. We might actually figure this out and - and more importantly, escape selective ignorance.

End of rant - thanks for letting me hold forth - - -

books

Geezer, well put! I am always willing to learn but when you guys tell me its my eyes when just this afternoon I ran into some really crappy flying conditions with a quartering 8-10mph wind & I couldn't make the old girl turn good either way very well but my down-wind turns were plumb ugly and even scary a couple times well its just not my eyes. Its the plane man I don't know why but every down wind turn for 3 loads was a handful then the last load it all changed. With the exact same power setting and RPM I was indicating almost 10 mph faster with the last load across the field and the turns were easy. Granted it has cooled off 5-8 degrees but that does not explain the increase in performance. I wasn't even hauling big loads, 240 when I have hauled 320 in the past. Whats up with that? And please don't tell me its my eyes, I promise thats not even a factor.
Dave

Ag-Dave, do you think the ideas of wind-speed gradient and/or gust geometry could help explain that? I know earlier on you thought 'maybe', but really - do you think those ideas have merit, or do you think they're off-base? And as I always ask my students - - - "and why?". Earnest question.

Re the air-driven spray pump - I have no guesses other than maybe something to do with power setting. If that's the case, it could be consistent with my gust geometry theory, but I don't yet know if that theory has any factual merit. TonyRV offered some ideas about that but I'm STILL digesting them.

turns

Gordon, The wind speed gradient idea might be a part of it but at the low wind speeds we work in and the relatively flat country I don't think its the answer. I know there are days when you can feel a much stronger wind at say 50'agl than down on the field but usually within the hour that wind is also on the ground and your done. I truely believe that just like the pump deal there is a component to these down wind turns that has been overlooked or not explained by current physics. If someone coule ever tell me why within the same hour and within a few degrees of temp change a airplane will go from flying like a pig to flying like its usually does I think we might be heading down the right track.
As far as power changes affecting the pump RPM, most of us use a constant power setting and a constant speed prop.

Yesterday I was watching my up/down wind ground speed on the GPS and my pressure. I was averaging about 115 up wind and 129 down wind on the first 3 loads then all the sudden on the forth load it went to 122-135 or so and the plane was fun to fly again. The pressure was varying about 4 psi as close as I could tell. The Pump RPM has to be higher on downwind, nothing else other than plugged nozzles could affect that but it would be interesting to see how much. Maybe there is a cheap electronic tach setup out there that could be set up to see how much change there is.
If it has something to do with prop wash then why the change? I think if we solve this we might be onto part of the down-wind turn answer also.
Wind is blowing this morning so I'm grounded for now.
Dave

Dave, could it be that small changes in wind, especially the turbulence part of the wind, might pick up or not pick up moisture from the ground, making rather sudden changes in air density? Or maybe temps close to the ground being way different than temps aloft, so that with turbulence there could be pockets of good and bad air - that come and go? I haven't checked or figured out how much effect a change in humidity might have on density. Just tossing out a possibility to look at - -

pumps

Gordon, The one thing about SE Montana is we have no humidity. Its pretty much a desert around here.
Dave

Well, so much for that "good idea"! Do you think there might be pockets of relatively cool and warm air?` I've noticed pockets of distinctly warm and cool air while waterskiing in Eastern Washington - probably a similar climate.

Aalexander, thanks. And i agree with you. Now if the same boat and a heavier skier is used youd need a little more speed both ways, right? Or a little higher power setting. Also if the boat turned sharp downstream the skier would sink or stall and probably need a higher power setting when 90 degrees to the stream. Because speed would be lost until the pulling source, engine, boat, recovers to your 4 mph stream speed. So could you take a minute for me and tell me why im not hooking these situations up to this thread? thanks in advance for saving my butt. doug

Just a question about physics and I didn't want to screw up that other discussion going on.
Wives Tale has it that it takes more airspeed to get airborne when operating off a real rough airstrip. (Not just actual distance but also greater airspeed) because you are loosing efficiency as the wing bounces up and down compared to one that is accelerating smoothly forward.

Anybody agree or disagree??

Yer a troublemaker!!!!! :lol: :lol:

S2D said:

Just a question about physics and I didn't want to screw up that other discussion going on.
Wives Tale has it that it takes more airspeed to get airborne when operating off a real rough airstrip. (Not just actual distance but also greater airspeed) because you are loosing efficiency as the wing bounces up and down compared to one that is accelerating smoothly forward.

Anybody agree or disagree??

Click to expand...

No, you actually get off shorter because you're flapping your wings like a bird.

Seriously, though it sounds plausible. But that's the thing about old wives tales, they sound plausible.

S2D said:

Just a question about physics and I didn't want to screw up that other discussion going on.
Wives Tale has it that it takes more airspeed to get airborne when operating off a real rough airstrip. (Not just actual distance but also greater airspeed) because you are loosing efficiency as the wing bounces up and down compared to one that is accelerating smoothly forward.

Anybody agree or disagree??

Click to expand...

To a point, yes...... but as airspeed increases, the bouncing will eliminate some surface drag which allows for more rapid acceleration. At the same time, sloppy pitch control (bouncing nose high) might add induced drag and slow acceleration. The extra airspeed will act similar to the benefit of added airspeed for gusty winds, as the wing is dealing with a similar factor of varying lift from the bouncing. So, extra airspeed might not be required, but it certainly adds a safety margin.

Every aircraft has a terminal surface velocity and you will be able to get airborne if you have enough power to exceed the airspeed required to get aloft before you reach that velocity.... and the runway/surface distance to get to that airspeed. This applies especially to downwind takeoffs, as well as other situations where the ability to accelerate is reduced, such as slope, surface contamination, or surface conditions (rough surface, high vegetation, etc).

S2D said:

it takes more airspeed to get airborne when operating off a real rough airstrip. (Not just actual distance but also greater airspeed) because you are loosing efficiency as the wing bounces up and down compared to one that is accelerating smoothly forward.

Anybody agree or disagree??

Click to expand...

I’m not sure on the benefit or hindrance to a “bouncing” wing but can say with an above average level of certainty that a cub crashing on a rough surface stops much more quickly then on a smooth flat surface. It’s also nice to have a fat girlfriend in the front to absorb some of the energy!

Lippy

Back to the pump pressure in a spray plane issue for a moment.

I am having trouble grasping that notion. I spoke to a very experienced sprayer yesterday. This guy has flown and owned a number of spray planes of different models. He has a lot of experience. I asked him about the pump pressure issue. He pointed out that in all the airplanes he's flown, either the pilot controls the pump pressure manually, or the Sat Lok system does so automatically to ensure proper application rates.

So, in a downwind pass, you NEED to have higher pump pressure, to ensure that you have adequate application rate.

He says this is done by the pilot, or automatically.

I know NOTHING (nada) about spray planes or their systems, so what am I missing here guys?

MTV

I'm a little afraid to jump into this one as I'm a mere novice compared to the talent on here.....and like you I have an inquiring mind and want to know.

Ag-Pilot wrote:

I ran into some really crappy flying conditions with a quartering 8-10mph wind & I couldn't make the old girl turn good either way very well but my down-wind turns were plumb ugly and even scary a couple times...... but every down wind turn for 3 loads was a handful then the last load it all changed. With the exact same power setting and RPM I was indicating almost 10 mph faster with the last load across the field and the turns were easy. Granted it has cooled off 5-8 degrees but that does not explain the increase in performance.

Click to expand...

This is likely over simplification but couldn't this be largely due to the air density?? I know you said it was only a few degrees....but could it be that there is a certain air density point for each individual plane where the performance dramatically decreases? We know that at higher density altitudes you need more runway to get off the ground...for both lift and engine performance. Couldn't this be just that point where the performance drops??

Just referring to the difference between the "ugly" turns and the last load. Not factoring in the downwind aspect as I assume it to be the unchanged from beginning to end.

cafi (the willing student)

spray pressure

Mike, Your guy is right about a airplane equipped with a Flow control, They are driven off the GPS ground speed and increase or decrease pressure with ground speed to maintain a constant application rate. I have owned and operated several. I am talking about all the airplanes that are equipped with a Satloc WITHOUT a flow control and with a wind driven pump. Yes, If you have a cockpit controlled fan driving the pump you can adjust the pressure in flight but without touching anything or even on a fixed pitch pump fan the pressure will increase on your downwind pass compared to your upwind. I have seen as much as 5-7 psi in a good wind.
I don't know a single agpilot that has flown these type of systems that does not agree with me. I'm guessing your guy either wasn't paying attention or didn't have a very good gauge or has never flown anything but a Cessna with a hydraulic spray system.
Dave

turns

Cafi, We see this all the time and it doesn't seem to have anything to do with DA. Rather, there just seems to be a difference in air unrelated to temp. Seems to me that it has something to do with wind close to the ground. Mornings are usually worse that evenings and it seems worse when there is a temp. inversion.
Dave

Dave,

I just talked on the phone with another experienced spray pilot, and he explained the system a bit better to me (or at least I think I understood his explanation a bit better). His explanation was that the first guy I spoke with was talking about adjusting the FLOW CONTROLLER, not adjusting the fan (which is connected to the pump and generally ground adjustable).

His explanation was similar to the first guy I spoke with, but I wasn't understanding what was being adjusted the first time. His point was that the flow controller must be adjusted on a downwind pass to ensure adequate application rate. This is done by adjusting the flow controller, NOT by adjusting the fan blades. So, the flow control increases application rate on a downwind pass. Makes no difference whether it's the pilot or satloc system doing the adjusting, at least on the systems he's describing.

So, if that's accurate, then I guess the question is really: Why would the system pressure INCREASE when the flow controller is delivering more chemical? There is no way that fan can be running faster (and increasing pump pressure) when running downwind unless the pilot is carrying more power on the downwind pass, which you said you're not.

Trying to learn here, and understand the phenomenon you described--not trying to start a fight.

MTV

MTV said:

There is no way that fan can be running faster (and increasing pump pressure) when running downwind unless the pilot is carrying more power on the downwind pass, which you said you're not

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Must be them gremlins messing around under there again.