Turns, with and without the wind

[bones]

Ok guys here we go again, this time i pinched a couple of posts off Dave's thread about engine out, and want to ask Ron to explain this situation at the end..

Posted by Chopper Ried;

Theory is great stuff and most of the time it works very well, most of the time, when you fly low and I mean low as in zero feet agl to 100 AGL you are operating in an area that is subject to the turbulence caused by the wind blowing over terrain, trees hills etc then you throw in the effects of whirly wirly or dust devils, heat thermals and or hot weather, you bring in a lot of variable's that DO NOT conform to the theory we have learnt.

I do understand that a lot of you guys here might have trouble getting your heads around the fact that I have spent a lot of time in a gyro and a thousand hours or so in a FW, mustering and so have been subject to a few things that changed my mind on flying to the laws of theory, particularly when flying close to the ground.

I use the term 'downwind turns' cause thats what they are but to be technically correct, they should be termed "low level downwind turns and the effects that diferent conditions can have".

I'm going to get howled down for saying this but I have expereinced conditions [again, at low level] where it has been impossible to do a 'downwind turn', in fact I have on a couple of occassions, had to skim along at 10 to 20 feet AGL, not at full throttle but at a a power setting that should have had the gyro climbing at 300 ft per minute but the gyro would not climb and most certainly, had a turn been tried, would have seen me with a wrecked gyro. You dont find these conditions every day but they are there and if you are not vigilant, you will get caught, hopefully, you will hit better air and be your gyro suddenly starts to fly like it should.

Even FW get into trouble [down low] once in a while, its officially called 'pilot error' but when you read the pilots story, it generally says the aircraft did not seem to be operating at full power.

Anyway, I'm taking the heat off everybody else at the moment and I still have plenty of stuff to keep you shaking your heads for a while longer so stay tuned to reality gyro flying down low working stock.

Then posted by Gyron

Brian, flying that low to the ground, you are most certainly letting ground reference influence the way you fly. Again, if airspeed is kept constant, turning downwind or flying downwind is the same as flying in NO wind.

Maybe low to the ground with trees and buildings, all the wake turbulence may make it more dangerous to do some manuvering. But I still stand by my statement that if airspeed is kept in check you can fly as normal in any direction no matter how strong the wind is.

GUSTY WIND is a whole other animal though..... The wind is not a problem, but the gusts can be, but thats not the point.

Now make sure everyone understands that we(Brian and I ) are talking about low level stuff here, as he said real low....
Now this just happened to me yesterday, its blowing about 30kts fairly constant, ok now im just flying around doin my thing,now because the wind is so strong im being abit cheeky and pull it it into a hover just above the trees to start of cattle no problems, as the wind drops off abit im slowly moving to far forward, so and THIS IS THE IMPORTANT BIT, ok im hovering at about 30kts ASI, so i open the tap increase it to 40kt ASI before i start to turn, by the time im in the turn it is 50 kts ASI, now normally full tap and 50 kts this thing climbs like a rocket, but all day yesterday, with the motor screamin and between 45-50 kts ASI turning down wind it would drop like a rock, and i made sure a few times that the ASI was up to make sure of this so i could come back and ask, and low and behold the subject was already on.
So can any one please explain to me why this is happening, and if you think im full of it, get on a plane and come over here and i'll prove it to you..
I'm not picking anyone here its just that Ron has said that it dont matter up wind or down wind if you keep a constant ASI, and i'm saying it does matter, and like Brian said we do it often enough to know when the machine is just not performing like it should....

Also the flying down wind thing needing more throttle is back on again to, dont know why but it does, about 300 rpm more

I'll be in and out for a few days so i might not get back to answering for awhile,, but i will be back

 

[scott heger]

Gee Ron and Chuck, maybe I am not as full of s**t as you think I am. I found another believer here. Mark has experienced the same problems in low level downwind turning conditions as Tim Mc and I have. Airspeed/ASI 's don't tell the whole story here, if thats all you think it takes to fly low level, you are headed for trouble one day when you least expect it. Going to be hard to chock this up to a bunch of low time inexperienced and unknowlegable pilots not knowing anything. Thats kind of what you doubters have been inferring. You have to realize more is to this. I know I am baiting you guys, but only in the interest of keeping everyone safe and flying a little higher as the winds get stronger to leave a larger margain of safety. Ron, after reading these accounts, you still think it is a good idea to try to go flying around in circles at 5 feet off the ground in 20MPG winds like you said you were going to do? You might be missing a couple of details, I really don't want to see you get hurt.

I am also interested in reading your answers to my last thread in Dave's engine out post regarding the gyroglider.

Scott Heger,Laguna Niguel, Ca N86SH

 

[GyroRon]

I am telling you guys that you are not maintaining airspeed. You can glance down at the indicator from time to time and see what you want, but somewhere in your turn your loosing airspeed and hence the need for more power.

Want to prove it right or wrong... mount a cheap video camera on the gyro that points at the airspeed indicator and go flying in the wind and when your done go review the video tape and watch and see if your not loosing speed in the turns.

You do need to make sure your airspeed indicator is working properly and is calibrated for this experiment to work properly. Ultracruiser 41 on the forum here, his old Gyrobee's airspeed indicator pretty much read 60 mph no matter how fast or slow you went, so if would be useless in this experiment....

 

[scottessex]

OH NO! NOT THE DOWNWIND TURN DISCUSSION AGAIN!!!

 

[GyroRon]

:rapture:

I know Scott, and I got baited into it by being called out in the first post! Someone get me outta here!

 

[Heron]

If you guys could focus on specifics and understand what one is saying we can all profit from reviewing the topic.
My guess is that we may have some new guys here . . .
There are different kinds of citrus fruit and no one is bringing apples in to the debate.
thanks
Heron

 

[Ralph]

The problem is, the subject is treated like a debate where we can all hold a vote at the end to see what is "right". Unfortunately, reality is not subject to our whims. Turns flown at a constant bank and airspeed are the same, no matter what the relationship to the wind. Wind does impact the ground track and pilots, ground-referencing turns, have created a whole mythology on the subject. When you have debates contrasting reality with mythology, no one wins and no one is converted.

Ralph

 

[Aussie_Paul]

The problem is, the subject is treated like a debate where we can all hold a vote at the end to see what is "right". Unfortunately, reality is not subject to our whims. Turns flown at a constant bank and airspeed are the same, no matter what the relationship to the wind. Wind does impact the ground track and pilots, ground-referencing turns, have created a whole mythology on the subject. When you have debates contrasting reality with mythology, no one wins and no one is converted.

Ralph

Guys and gals, the problem with this debate is that the mustering guys do not operate like the sedentry flying majority, at a constant angle of bank or constant airspeed.:help:

Aussie Paul.

 

[Al_Hammer]

I see a problem in looking at the climb performance of the gyro at at, say, 45 mph, and trying to relate that to the downwind turn performance.

In a steady rate climb, lift does NOT need to increase above 1G, except initially, to get the climb started. The work of lifting the gyro against gravity is done by the prop in the form of increased thrust, which ovecomes the increased drag of the rotor at a higher angle of attack.

By contrast, in a quick turn to downwind , in a mustering situation, the bank angle may approach 60 degrees, I'm guessing. The lift would be now exactly 1/2 of normal. The gyro will sink like a stone unless the stick is held way back, requiring much additional power to hold airspeed.
It may be that sufficient extra power is not applied and the airspeed is maintained only by virtue of a descent.
Then the pilot wonders why a downwind turn results in a sink even though the airspeed is constant.

 

[scott heger]

Al, for reason of keeping this simple, the sink is occuring at a point after returning to level flight from the turn. It could be 10 seconds later, not just exiting the turn. I know this is easy to say that the pilot is not maintaining airspeeed, but I have watched the ASI, and it is not bouncing around lower as should be the case in a gust or other distubrance. Just 40-45 MPh indicated, and falling like a rock at WOT. I fully understand it does not follow what should be happening and is easy to disbelieve, but it does happen every now and then.

I am just warning those that have not experienced this that this can occur, and to fly at a higher altitutde that would give you enough time to take some action, like turning back into the wind .

Scott Heger, Laguna Niguel, Ca N86SH

 

[Al_Hammer]

Ok, Scott, I didn't fully understand the scenario.

 

[C. Beaty]

By contrast, in a quick turn to downwind , in a mustering situation, the bank angle may approach 60 degrees, I'm guessing. The lift would be now exactly 1/2 of normal. The gyro will sink like a stone unless the stick is held way back, requiring much additional power to hold airspeed.
It may be that sufficient extra power is not applied and the airspeed is maintained only by virtue of a descent.
Then the pilot wonders why a downwind turn results in a sink even though the airspeed is constant.

You’re right, Al, but that’s just another way of saying the people falling out of the sky are flying by ground reference.

I thought of you this morning when I tried to run a floppy that contained Marie Brock’s letter about Martin Hollmann. The floppy wouldn’t run on a computer that had either W2K or WXP operating systems.

I had to sort through my trash heap to find a motherboard that would run W95 and for which I still had drivers. What a miserable OS!

I imagine in your case, a P133 and W95 is just a prop like Jack Benny’s 1926 Maxwell.

 

[Al_Hammer]

What a miserable OS!

yes, Chuck, its miserable, but familiar, like an old shoe.
I'd love to tell you that it's a prop, like Jack Benny's fiddle, but, I'm not that talented a comedian.

 

[Udi]

There are so many things I don’t completely understand in life (still trying to figure out my wife…) and at work. It is true that reality, or the laws of physics, don't care about our opinions, but it would be pretty arrogant of us to claim that we have a complete understanding of the aerodynamic problem presented above. "The gyro doesn't care about upwind or downwind because it is moving inside a moving mass of air - bla bla bla" -- is the simplified version of this problem. The real problem is much more complex, and I don't think anyone here has an answer for it. Does anyone here have special glasses that allow him to SEE the true air flow close to the surface? For example, are the trees generating rotors? What is the size of the rotors? What is the vertical component of the rotors? How would these rotors interact with the rotor blades, as they hit them from the front, from the back, and from the side?

I don't know whether wind rotors have anything to do with the problem Mark has posted above, but I wouldn't be so cocky as to suggest that Mark had one too many pints before he went flying. Mark has described the problem very carefully and he made sure his airspeed was in check all the time. Do you have a reason to doubt Mark’s observations? If we don't have an explanation to the problem as presented maybe we should just say, we don't know...

Mark – I have some questions. When you made your downwind turn – in addition to maintaining airspeed, did you maintain altitude? What was your bank angle? Would a shallow bank be as bad as a steep bank?

Udi

 

[brett s]

It's pretty easy to figure out to me, there are really only two reasonable explanations:

1. Flying by using ground reference & not maintaining airspeed.
2. The air mass you're flying through is moving vertically as well as horizontally.

Or a combination of both of course - as Udi pointed out, we can't see air currents. But you can sure figure out after a while where you're likely to see issues from anything disrupting the wind (or there's be a very short life expectancy for mustering or ag pilots). That includes buildings, trees, or even terrain features...

 

[C. Beaty]

Brett, the wind is always tilted near the ground due to surface drag. That’s why Dutch millwrights always tilted their windmill axes ~10 degrees nose up. A balanced horizontal axis weathercock will show the tilt angle.

But flying with respect to the air mass isn’t any different upwind or downwind. It does take more power to fly in the tilted region between OGE and say 50 ft. due to the downward component.

 

[Heron]

Udi
Every time this discussion comes up, one is changing some parameter and the other one still on the prior subject.
Two different situations will never equalize opinions.
The discussion should be how the wind affects turns . . .
Funny thing is, the glider tied up against the wind will get airborne and not the other way.
Remove the rope and all changes (pilot in or not)
One component of lift always change in turns, no matter what altitude you are.
Yes . . .everyone is right!
I still loose 100 ft in every round around the pattern, cant keep that nose were it belongs . . .
I need more low level flying to get the feeling and make my approaches better.
So far flying is easy.
thanks
Heron

 

[Udi]

Chuck - the wind, on average, cannot be tilted as you say, due to conservation of mass. For every cubic meter of air going down there must be another cubic meter of air going up somewhere. Wind, on average, must flow parallel to the ground. Thermals and wind sheer are classic examples of localized wind with a vertical component, but in both cases there will be areas with opposite vertical wind direction. I am not sure why the Dutch built their mills facing 10 deg up, maybe because the mill was facing obstacles that were causing the wind to flow down into the mill.

Whatever phenomenon we are looking for must be symmetrical on average in order to conserve the mass but localized enough - i.e. smaller than one rotor diameter, to affect the lift in relation to the direction of movement.

Udi

 

[Fl90]

Hi, when I make low level down wind turns I have to make a concious effort to exagerate the turn. If I don't, I find myself banking into the turn to shorten it. Upon exiting the turn, my airspeed will be the same, but my disk angle will be on the back side of my power curve (i.e. same speed, 300 rpm more). The gyro feels like mush and will sink. To correct the sink I have to move stick forward, gently. This always looses a small amount of altitude, and when you're 10 or 15 AGL it is hard to convince yourself to do it. But, I have found as long as your ASI is correct you begin to gain airspeed and altitude quickly. Also, it seems to loose less altitude the closer I am to the ground.

This is just my observation. This is not a recomendation or an explanation for or of anything.

If anybody feels this is obsurd, fire away. I have thick skin. I do things that work for me, however, I can't say they are right or wrong. Phil.

 

[Harry_S.]

Aarrgh...I stayed away from this topic as long as I could.uke:

Way back...when I first started in the gyro movement, I didn't know much more about *gyro* physics, than I know know.

I had many hours of glider time...with no instruments and when I transitioned to powered flight...I still had no instruments. The only *instrument* I had was the useless, pith ball wind gauge. I flew for many hours in this manner. I didn't need any gauges; by that I mean, flight inst. eg, IAS, altimeter, compass etc. Don't get me wrong now, inst. are good if you learned to fly by the numbers. I have a good supply of inst. in my RAF and I really only look at the eng. inst. most of the time.

I still essentially fly by feel and seat of the pants, if you will, and I have no problems...I'm talking of gyro flight now...not FW.

I have experienced *sink* in turning downwind and it was at full throttle and...let's forget that weak suggestion... as to looking at the ground. If you're holding a stationary point over the ground, into a 25 mph wind, at full throttle and you turn left or right, how are you not goin' to *sink*...explain that to me. To recover you must maintain full throttle, and apply forward stick to gain additional airspeed.

Ron and others...may I offer a suggestion...if you trust your flying prowess...cover over the ASI, Rotor Tach, Eng.Tach, ALT. and go fly. I'll wager you will like flying a bit more...after a bit?!

I'm open for questions.


Cheers