Sgt. Meyer

I haven't seen it, Hugger. They (and I'm not including the Inertial crowd here) argue steady wind, no ground track, you argue trying to fly a ground track at a slow speed in a high wind. I think their main argument with you is simply that you are arguing a different point. Your Point is not THE POINT. The Fact of the Hazard is indisputable. The Reason for the Hazard is the Point.

The Myth is that turning downwind makes you lose airspeed. The TRUTH is that if you lose airspeed in a downwind turn it is because you mismanaged it. That if you lose airspeed it is probably because you perceived that you were going much faster than your airplane actually is in the (moving) air and you unconsciously slow down. Whoa! Pull back. Stall. Spin. Crash. Die. In my mind the next turn is even more hazardous. When you try to maintain that square corner in your turn to Base and turn too steeply from downwind to keep from drifting further downwind. The steep turn at low airspeed and low altitude is a killer. Add some poor coordination. Whoa! More rudder! Pull back. Stall. Snap. Crash, Die. First one to the scene of the fatality. To a Modeler this means taking your toy home in a paper sack.

The high-time pilots and F/S instructors and engineers will not disagree with that. Remember that it is usually low-time pilots who instinctively get themselves in this position. That is why we try to teach them how it works before they go out solo and get hurt.


No Cub, no Champ, no T-38, no L-1011, will fly a traffic pattern the same SHAPE in a 30 kt wind as it does in a light wind. But they CAN turn downwind without dying. It's two different arguments.

I won't go on about how long I've been flying. I just love to fly. I love to teach. I'd like to buy YOUR dinner.

Steve.

chuckk2

Downwind turn with a model AC - - -
My usual practice is to drop the nose and add power (if available) before I even think about using an extreme bank angle.
If the wind is high, and for whatever reason, I'm making an approach to eventually land, I just might make a much higher than normal pass
and give myself the altitude to recover, if the needed bank angle might result in a stall. Occasionally, the field I fly from can make a downwind landing necessary,
due to the sun, obstructions, or wind turbulence due to adjacent trees.

If I were trying to fly a full size light AC about a point in windy conditions, I'd be using throttle and bank (trying to maintain a "standard rate turn" complicates things) as well as the elevator, and to stay co-ordinated, the rudder. (watching "the ball" out of the corner of my vision, and the "point" in the other)
The ball is important enough that when doing this sort of thing often, some AC owners add a second simple ball in an alternate location.
Back in the 60's, one of my instructors was a survivor/veteran of the USAAF WWII civilian instructor programs, as an instructor.
He really had a fixation on precision and spin training, but didn't care much for aerobatics. The other main instructor was a corporate pilot,
and trained students to fly "by the instruments and numbers".

SushiHunter

Is it a fair statement to say that if an aircraft takes off into the wind, becomes airborne, then makes a turn to fly the same direction that the wind is traveling, the a/c's ground speed increases but the actual airspeed doesn't increase as rapidly as the ground speed does? I worked at a small airport for many years during my youth and I would always notice how the aircraft's speed would dramatically increase after taking off into the wind and then banking into a 180 degree turn to fly in the same direction that the wind was traveling. So when the plane would become airborne for example, the ground speed of the a/c was 120 knots but since they are going into a headwind that is moving 5 knots, their airspeed is 125 knots, when the plane changed direction and maintained 120 knots with the same 5 knots of wind, their ground speed was now 125 knots while the actual airspeed was 120 knots. Would this be accurate under these specific conditions?

bjr_93tz

No.

All things being equal, the pilot should have maintained his 125 knots takeoff airspeed (120 knot groundspeed) and ended up travelling downwind at 130 knots groundspeed after the turn.

The speed mismatch could be an optical illusion, or the plane is losing airspeed through the turn because it's lacking the power to cope with the increased drag during the turn, or the pilot is trading off a bit of airspeed for height.

jfetter

Agreed, the plane has no concept of "wind" when flying and unless in turbulent air, will happily fly figure eight's without even knowing if head, tail or cross. A pilot without a ground reference couldn't tell the difference or feel any change throughout the maneuver, there is no push from a tail wind or drag from a head wind from the POV being air speed. If a plane takes off and ends up at altitude, in an air mass moving evenly @ 1,000 MPH, it won't make a lick of difference, except to the pilot who will never get where's he's going ;-)

Jack

Rob2160

This is the key!.

Sitting on the ground at the Equator. Are you:

1. Moving at 0 Mph?
2. Moving at 1000 Mph (speed of earths rotation)
3. Moving at 60,000 Mph (speed of earth around the sun)
etc etc.

The answer is: all of the above.

SushiHunter

This sounds about right. And If so, the increase in speed would not be just an optical elusion because the plane starts of at 120 knots ground speed and after the 180 degree directional change is now traveling 130 knots ground speed. I know when I do the exact same thing in the same exact wind conditions with my r/c plane, it's hauling ass coming back around moving the same direction as the wind and I've not increased throttle or changed the pitch of the plane.

cfircav8r

My Feedback: (1)

The problem arises when you see that increase as an increase in airspeed.

Airplanes400

My Feedback: (349)

1.) WRONG
2.) WRONG
3.) WRONG

The correct answer is; "Who cares. Just get me another drink!"

================================================== ========================

And it is scenarios just like this that have women shaking their heads at men, laughing their asses off, and becoming lesbians.

Airplanes400

My Feedback: (349)

While I can appreciate the work and time put into this demo. Doing this on a $200 simulator program doesn't prove anything, and here's why ...

#1 --- It's only a $200 program

#2 --- My RealFlight sim program allows me to cut the throttle to idle on a turbine jet while on final approach, and then land safely and smoothly on the runway. While in real life, if I were to do that, the jet would crash long before making the runway.

Next time I'm at FlightSafety, I'll try this on a $14 million dollar Phase 3 Simulator.

Rob2160

LOL, I'll do the same in 2 weeks at the Bombardier Global Express sim in Montreal. (They don't like you taking videos inside the sim but I'll see what I can do)

Failing that, next time I ferry the Hawker 900XP empty I will repeat my 360 orbit in the middle of a jet stream.

Realflight does have aerodynamic inaccuracies but I think RZeilin did a very good job with those two videos and his demonstration is valid.

+5 on he beers, as a young instructor I used to enjoy debates on aerodynamics, now airplanes can fly by pixie dust for all I care. The only thing that matter is "What is on the menu today?"

https://www.youtube.com/watch?v=FkwT9Jj4nF0

sensei

Great job guys, it's been a long time since there was this much bi#%$*&ing, I don't know about the rest of you but when flying my models, who cares about a stinking downwind stall anyway, I just start a harrier roll and no more stall problem because they don't stall when rolling silly rabbits... LOL

Bob

jfetter

I think it's fair to say throttling down when turning or travelling downwind in a stiff breeze is common, maybe even occurring at a subconscious level for many because again, we perceive the planes' ground speed, never its airspeed. Assuming others do this and not just me, it's also fair to surmise a lot of this myth revolves around that, as many stated already. Given we all crash many times before becoming accomplished R/C pilots, and don't understand all the principles involved in flight early on, it's not really surprising that the perception of losing lift when turning downwind is the end result...

Jack

cymaz

Here you go..... if you lot start arguing against the FAA I give up.

SEE PAGE 5

cactusflyer

My Feedback: (4)

There is the answer....it's INSTINCT not PHYSICS that cause the problem...end of story.

Tailwinds,

John

cymaz

And the fly in the ointment was that the FAA is from the pilot in the plane. R/C pilots have no or very little help when it comes to how the airflow is affecting the plane until something happens.

'This downwind turn is not dangerous because
of a loss of lift but due to an illusionary
difference. When at a low altitude flying
into the wind, when a pilot turns downwind,
the pilot senses an increase in
speed. He mistakenly interprets this as an
increase in airspeed and not groundspeed.
Since he thinks that his airspeed has increased,
he subconsciously increases his
pitch causing the airspeed to decay. If airspeed
decays too much, the pilot risks a
possible stall.'

Sgt. Meyer

The effect is the same, whether you are in the cockpit or on the ground holding a transmitter. You only have to change ONE WORD of this explanation to make it apply to RC models:

'This downwind turn is not dangerous because
of a loss of lift but due to an illusionary
difference. When at a low altitude flying
into the wind, when a pilot turns downwind,
the pilot SEES an increase in
speed. He mistakenly interprets this as an
increase in airspeed and not groundspeed.
Since he thinks that his airspeed has increased,
he subconsciously increases his
pitch causing the airspeed to decay. If airspeed
decays too much, the pilot risks a
possible stall.'

But you are right, cymaz. Unfortunately, the RC pilot cannot know precisely what his airspeed is. He has to rely on experience. He should anticipate the potential problem. The engine sound helps, too.

SM

SushiHunter

And they used to tell the "new guys" that once the ship crosses the equator, the water in a flushing toilet spins in the opposite direction.

RZielin

My Feedback: (1)

It would be nearly impossible to perform this demonstration accurately in the real world, so real "proof" by your terms would be tough to show. I agree my demo is only a computer simulation, but I think it is a valid demonstration of all the relevant principles. The sim is flying the simplest scenario possible, no turbulence, no change in control surfaces, no change in throttle. The plane is trimmed to lose altitude immediately at the slightest loss of airspeed. I don't think it takes a $14 million dollar sim to run this scenario very accurately. RealFlight has accurate enough aerodynamics for pattern flyers and 3D flyers to practice complex aerobatics effectively, and many RealFlight recordings are used as training tools for aerobatics including spins, snaps, harriers, you name it. If it can do that stuff credibly enough to be useful for learning and teaching, it can certainly fly a plane in a perfect circle in dead calm or steady breeze and get the right airspeed results. Even if it's "off" by a full 10% (which I'm sure it isn't), my demo is still strong evidence.

Thanks for commenting on it though, and I really really look forward to seeing what you can do on that Phase 3 Simulator. I sure hope you can bring a tripod for your smart phone and video it for us!

Airplanes400

My Feedback: (349)

I started that rumor years ago. Glad to see it caught on!

Airplanes400

My Feedback: (349)

It's always nice to have a window seat while dining.

Please don't get them started on pixie dust making planes fly. This topic has dragged out long enough. But on second thought ... maybe the theory about pixie dust would be a nice change.

Rob2160

Here is the video to prove it… http://www.youtube.com/watch?v=zf00mEe9EOs

and crossing the equator.. my coffee swirl changes direction but only in a tail wind.. https://www.youtube.com/watch?v=rt1eABk27NY

Beautiful state you live in, currently in Miami.

Airplanes400

My Feedback: (349)

There's no refuting the Peter Pan theory. That is solid evidence. Superman can back it up too.

Yes, Florida is beautiful ... Especially the women in Miami. They're also fun to play with, but hardly any of them are keepers. Don't waste your time on this site if you're in Miami. Get out there and find those women. Just don't bring up the "turning downwind" topic.

chuckk2

It's all relative, so does E=MC^2 apply? (Heh!)

cymaz

Sorry to debunk the downwind turn myth and stalling.
However in the States isn't there a museum that shows the myth that men lived with dinosaurs?
Noooooooooooo. I can feel a backlash coming on.