mtthomps

My Feedback: (2)

It is not automatic with me. I also have to actively resist the urge to apply more power when turning from upwind to downwind. I think that the plane is going to stall. Once you get the hang of it though, it is a lot of fun to watch an almost stationary (with respect to the ground) plane accelerate radically (groundspeed) when I turn downwind. (I like to fly in LOTS of wind). I just have to tell myself not to do anything different in my turn than I would normally do.

mtthomps

My Feedback: (2)

I mostly fly in lots of wind because almost nobody else wants to fly! I have the place to myself.

Msaint

My Feedback: (5)

Actually if I think about it like this it makes more sense. If you are flying 20mph into a 20mph wind your ground speed is 0 and it will look like its sitting still to you but your plane is flying at 20mph when you make your downwind turn from the 20mph wind your groundspeed will go to 40mph but your plane will still have an airspeed of 20mph thus having no effect on the flying surfaces unless you try to correct for the ground speed changes. So on the same token if your plane was to cover 40 ground miles in an hr in a 10 mph headwind then your plane would have to fly at 50mph airspeed thus using more fuel and power. Do I have that right?

Am I making sense to myself. Oh and could someone explain the Bumble Bee thing while they are at it.

Msaint

My Feedback: (5)

Yes heh I love toying around flying backwards when its windy.When I sit back and think about it I guess what I learned flying on the slope was not to make the flying surface corrections I used to before. Although I think still do a little when flying power planes heh.
I guess now that I learned whats going on Ill pay more attention to not making changes on the controls due to ground speed. On the slope the darn things are going so fast all I do is try not to get knocked out of the air and I never really have time to think about any differences in speed. All and all your lil physics lesson should make me a better flier after all these years.

Thanks for your patience with this ole fart

Now about the Bumble Bees !!!!!!

xtratorque

would ailerons help with the wind at all? It doesn't come with them but is there some way I could add them to it.

Bipe Flyer

Well, by looking at it you wouldn't think the Bumble Bee would fly, but it does.

Msaint

My Feedback: (5)

Hahaha Darn has anyone kited that for RC yet. That looks like it would be a handfull and a 1/2 in a 1/2a.

Bipe Flyer

A guy in one of the neighbouring clubs built a ½ scale RC Bumble Bee. It has a 40" wingspan and a G62, yes that's right a 62CC engine for power!

http://www.geocities.com/g_villette/beefli.htm

BMatthews

It's OK MM. They didn't issue me with a Golden Scepter or anything when I signed on for the job....

Besides I guess I am wrong. I always used to subscribe to the moving air idea but recently I got to thinking about the momentum bit that I described with the 10 mph glider into the 10 mph wind. I guess I was fixated on that part.

Thinking about it more I realized that I don't have to compensate when doing thermal turns with my sailplanes even though on occasion in higher winds the model is almost dead still on one side of the circle and humping along quite good on the other while I only have to make very minor corrections if any for turbulence. Certainly nothing cyclical that is related to where in the circle I'm flying. That convinced me. You win mtthomps.

Now where's that User Account Delete button........




JUST KIDDING...

Mavericman

just trying to defend you.

you will need ailerons in high wind conditions to compensate for all of the turbulence(bumps) in there air.

but if all i hear is true, airspeed always staying the same, why are people so terrified of flying in wind???

Bipe Flyer

There's no problem fling in the wind, it's taking off and landing in the wind that can be difficult. A constand wind can be fun, but gusty wind is a pain.

Mavericman

Taking off and landing are my favorite part! and i think theyre easier than initially flying the plane!!!

Msaint

My Feedback: (5)

Heh its that landing part that allways gets me no matter what the wind is. You can allways decide not to take off !

BMatthews

Wow, my 'puter died tonight. I'm reduced to using my wife's machine until I get my cheap old retired 400 out of mothballs... Guess it pays to be part of a 'puter geek family...

I was just typing in that ailerons would be a wise thing for windy weather when the lights went out.

But yes they do help to handle the rough stuff. So much more positive. Also the near lack of dihedral means it's not trying to roll away from side gusts.

Big Al-RCU

Hi guys,
Not to flogg a dead horse, but here is how I like to see it.
Suppose that you are flying a light plane just above a nice fluffy cloud layer. You do a series of figure eights. There is no perceptable wind, even tho both you and the clouds may b e moving downwind at 50 MPH. Short of a GPS, there is no way that either you or the plane can determine if there is any wind or in which direction!
Sorry, just had to jump in............
al

wild fred

My Feedback: (3)

weend? I din' wurry 'bout no stinkin weend!

fastlash

My Feedback: (7)

Iam with wildfred all the theory in the world don't mean squat, if you don't go out and do it,and the take offs and landings is were the throttle and aileron management play the big part, the plane can bouce around all it wants tell its time to land, heli experience has been a big help in avoiding landing panic, the pucker fact with them whirly birds is ten times greater,and more expensive, my blades alone are $110, this discussion her has been very interesting and i have learned a few things, also my plane does know the diffence because I had a discussion with it and I yell up at it and let it know that Iam changing its direction

Mavericman

I dont have to worry about throttle because i am running a black widow, I always deadstick. hey wildfred, do you know hoy to kill a widow in midflight? nosedive?

Bipe Flyer

If you nosedive long enough you'll kill it.

fastlash

My Feedback: (7)

Great reply BF, your a funny guy

beenie

My Feedback: (9)

mtthomps,
Your arguments were very concise and right on target. You did a better job than I could have explaining such a difficult topic. The problem that we face in RC is that we are stuck to the ground and have no airspeed reference, only groundspeed. So things seem to happen relative to the ground, when they are actually happening relitive to the air, which we cannot see. Wind, as we percieve it, is the motion of the air relative to the ground. This is of concern to us because we are on the ground. As soon as the plane's wheels leave the ground, it is moving with the air. It only sees the wind relative to its foward motion, not relative to the ground. The reason that it is usually harder to fly in the wind is that as the wind passes across the ground, it runs into trees and buildings and mountains and other things. This causes the wind to become turbulent, similar to a stream with rocks in it. The plane rides in this turbulance and we see this as the plane bouncing up and down and whatever. Similar to a boat in that turbulant stream.
Hope this helps,
Ben

mtthomps

My Feedback: (2)

Thanks a bunch beenie! I did make one mistake though. I stated that an approach in wind requires a steeper glideslope in order to maintain the same airspeed. I mis-spoke. What I meant to say was that the approach needs to be steeper in order to reach the end of the runway, from the same distance away horizontally. Approaches that start from the usual calm day distance and height will intersect the ground long before reaching the end of the runway because there is not enough groundspeed present. If pilots try to strech this out with application of up elevator without some power added, they will unexpectedly stall on approach. The stteper approach results in an acceptable groundspeed, but a rather "hot" airspeed when reaching the runway threshold. This is acceptable, because the plane will decelerate quickly enough because of the headwind. It has plenty of time to reach an acceptable "set it down" airspeed because the groundspeed is that much less than the airspeed. The plane will appear to "float" for a longer time after the flare, but it will be starting from a greatly reduced groundspeed, and therefore will not travel as far down the runway in the time it takes to slow the plane down to landing airspeed. The fact that it does not seem to take much longer is because our brain uses regular physical events to time the duration of most things. If the "flare to touchdown" time was 20% or 50% longer, most of us would not give it a second thought. This is to us the "time that it takes". If my watch was to suddenly start taking 20% longer to tick off seconds, I would assume that it was ME that was thinking faster or speeded up, because the watch's standard of time is trusted almost absolutely. But alas, I am off on a tangent, which after 6 hours, could get really bad......

DICKEYBIRD

Normally I steer clear of the 'ol upwind/downwind turn argument (nothing new here, it's been going on forever) because, like politics, one side almost NEVER changes the other's mind and the rhetoric gets more and more vicious until it gets unbearable. Just do a search in any internet model aircraft forum and you'll see what I mean. Funny though, I've never seen it go the way it has in this forum, ie: one group getting confused and totally changing it's views on the issue.

I feel I have to get involved because mtthomps' agenda WILL cause someone to lose a perfectly good airplane for no reason. Let me give you a hypothetical flying scenario and see what you think.

mtthomps has entered his first scale contest with a .60 size CAP 21 (or whatever.) The wind is blowing left to right, 25 mph & steady, right down the runway (hah, told you this is hypothetical!) He has just begun performing one of his favorite maneuvers, a slow "racetrack" pattern (at 35 mph, 10 mph above stall speed) maintaining an altitude of exactly 6 feet with the 180 degree turns beginning at exactly 75 feet to his left and 75 feet to his right. This impressive maneuver demonstrates his ability to stay in complete control of his CAP and also the CAP's low speed capabilities, right there in front of the judges and spectators, down low where everyone can appreciate it.

He knows that doing this maneuver at 10 mph above stall speed is dangerous but well worth the calculated risk because he has done it many times before at his field where it's usually calm. He's able to complete it safely due to his ability to make low altitude turns at low speeds with the perfect amount of control inputs needed to guide his CAP along the desired flightpath, just above stalling speed. Knowing that his CAP is in no way affected by the river of air it's flying in, he sets the throttle at the point that gives him his 35 mph airspeed and completes the initial upwind pass, right to left. At 75 feet off his left shoulder, he initiates the 1st right hand turn and as it progresses, the hair sticks straight up on his neck because the CAP is somehow trying to fly way inside of it's intended path with a shorter turn radius. He's puzzled but instantly and gently adds the perfect left aileron and and rudder input to keep the CAP on it's proper path.

As the turn progresses, he notices that the 'ol CAP is a little more sluggish than normal but says "Hmm, I had to add more aileron and rudder than usual to keep her on the correct turn radius. That caused a little more drag and she's losing a little altitude due to the drag induced speed loss, but a little more elevator input will maintain the necessary 6 ft. altitude." He then notices that the increased angle of attack needed to maintain altitude has scrubbed off a bit more speed but begins his mantra: "My CAP is not affected by wind, my CAP is not affected by wind, my CAP is not affected by wind." As his CAP comes around through 120 degrees, continuing on it's proper turn radius and approaches 180 degrees, he says "Wow, it's getting harder and harder to stay at 6 feet, I better add some more elevator to stay up where I'm supposed to be." As he adds more & more elevator, the induced drag goes higher and higher which in turn cause further loss of airspeed. He says "I really need to add some power but my CAP is flying in a river of air and WILL NOT be affected by it. I won't add power because it wouldn't look pretty to the judges for my CAP to have an even higher groundspeed on the downwind leg!"

As his CAP continues to mush lower and lower, he applies more and more elevator to stay at the necessary 6 ft. altitude. As it begins to waggle it's wings alarmingly, his automatic stall warning reflex finally drowns out the mantra in his head and he jams on full power. The big scalelike prop turned by it's perfectly tuned Belchfire .60 takes a massive bite of air and the torque and P-effect reaction yaws the CAP hard to the left. He adds right rudder and aileron but it's too late! The poor CAP screams "ENUFF ALREADY" and snaps viciously onto the runway in a heap of smoking wreckage.

The above scenario is maybe a little extreme, and definitely verbose but it illustrates the point I'm trying to make in a "real world" way that applies to our planes just the same, at more normal speeds and altitudes. I don't pretend to know the physics involved but, for me anyway, I'll take empirical data every time! In the real world in which we fly, aircraft ARE affected by wind because we all fly from a fixed location on the earth, trying to keep our favorite toy in sight at a fixed relative altitude. I like to think that the whole flight process is "tilted" upwards by wind, ie: the flightpath is higher on the upwind run and lower on the downwind run. If we don't have enough altitude to clear the ground on the downwind pass, we have to add sufficient power to maintain that desired altitude. Not a problem at reasonable altitudes and speeds but definitely a problem at low altitudes and speeds in windy conditions.

OK, who's next!

ps: In our next discussion, we'll get into the dreaded "Downlight turn" syndrome, or: "Why models covered with transparent covering always fly better."

mtthomps

My Feedback: (2)

In your illustration, the sharper turn (mor bank, more up elevator) would occur on the right hand turn on you right shoulder, not the left shoulder. With the wind blowing from left to right, and the right hand turn taking place 75 feet off of the left shoulder, the ground track taken by the plane will have a smaller radius than if performed in a dead calm airmass. In that situation, the turn would have to be shallowed out in order to maintain the same precision ground track. A shallower turn would result in LESS drag at thi point. However, the situation you set up WOULD occur in the turn to the right when done off of the RIGHT shoulder. In this case, the turn radius ON THE GROUND would be too large, and would require a steeper bank angle, and more up elevator to maintain the level turn. As I stated previously, any time there is a greater bank angle present, the airplane requires either more entry airspeed, or more power added in order to maintain the airspeed. Steeper turns bleed off airspeed faster because of the higher drag induced by the greater angle of attack.

Try again. I am on VERY firm physics ground here. In my flight training, we practiced s turns over a roadway in heavy wind. When turning upwind, a steeper bank angle is required in order to maintain the same radius of turn WITH RESPECT TO THE GROUND. If I was doing it at close to stall speed, I would be watching the airspeed indicator, not the groundspeed at which it felt like I was traveling. Any time a steep turn is performed at a low airspeed, power is required in order to maintain that airspeed. This is also true at a high airspeed, but it can be safely ignored because of the large margin between the turn airspeed and the stall speed. At a low airspeed, loss of enough airspeed to get you close to stall speed is unacceptable, and power is much more important. There are plenty of aerodynamicists, and professional aviators that will back me up here.

beenie

My Feedback: (9)

Dickeybird,
You may have said it the best

-In the real world in which we fly, aircraft ARE affected by wind because we all fly from a fixed location on the earth, trying to keep our favorite toy in sight at a fixed relative altitude.-

But, the airplane isn't affected by the wind, your perception of it is. The wind direction and intensity is very important to the RC pilot because he/she is unfortunatly stuck to the ground. This is not a political debate or an attack on personal beliefs, it is well documented physics. As a profesional aviator and an instructor, I teach this stuff and give demonstrations that prove what mtthomps and I are saying. If you were floating in a balloon controlling your airplane, the wind would be irrelevent. There would be no wind, just the ground moving below you. But you wouldn't care about the ground because you wouldn't be on it.