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May 26, 2021, 04:01 PM
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JimboPilotFL's Avatar
Quote:
Originally Posted by hook57
Downwind turn.??.?.. So If the aircraft’s indicated (calibrated/true) airspeed is 15 knots above the AFM published stall speed at a given weight while flying directly into a 20 knot relative wind, that aircraft will not stall?? But if it is flying within the same relative 20 knot wind from the opposite direction it will? Really? Considering the wind velocity is measured relative to the ground, can you explain how that works? (Especially given that the “downwind turn equates to a higher ground speed as the turn is initiated”). So, how does the airplane stall in a “downwind” turn versus the “upwind” turn, considering wind velocity is relative to the earth’s surface (at least as a reference point)...... and not measured in reference to an aircrafts position relative to the air mass it is operating in, irregardless of the direction or velocity of that air mass. p

By the way, it appears that it might have been an “accelerated stall”, which cares nothing about downwind, crosswind, or upwind turns....
It is hard to judge the airspeed of a model airplane going down-wind. It is easy to mis-judge the planes airspeed before making that final turn to line up with the runway. It might seem like it is flying fast enough but because it is going with the wind the actual air speed of the plane is very slow. It is a very common occurrence for a plane to stall in that situation and you should be familiar with that if you fly models. It is a matter of perspective from where the pilot is. It is not the airplane it is the pilot on the ground.
Last edited by JimboPilotFL; May 26, 2021 at 07:59 PM.
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May 26, 2021, 06:07 PM
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Use whatever terms you chose, but part of that inside wing reached it's stall angle of attack and stalled. Holding onto "up" elevator kept it stalled and the "right" aileron wasn't helping.

The plane had plenty of airspeed to recover by itself by neutralising the controls as it wasn't in a deep, slow speed type stall.

Seen it happen to a scale de Havilland Comet. It managed to get itself pointing nose straight down still with good height and old mate just wouldn't get off the elevator and let it fly. For me, fixed wing is 2nd nature now but I'm on the heli learning curve at the moment and it's bringing back memories of dumb thumbs and how easy it can happen..
May 27, 2021, 01:08 PM
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Coupez's Avatar
Looked like a stall followed by a spin to me.

But whether it was a stall or a tight spiral, you'll never get out of it if you continue to hold up elevator.

Most of my models will recover from spins by themselves if controls are released. So whether it's a spin or a spiral, the recovery procedure is:

- Release all controls, and
- Throttle = idle
- If spinning, wait for the spin to stop
- Level the wings
- Gently pull out of the dive

If your model has a tendency to "lock in" to a spin, you might also need down elevator or opposite rudder to stop it.
Jun 10, 2021, 06:32 PM
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i wish i could see the video.
Jun 10, 2021, 07:55 PM
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I think you got a little slow and stalled and spun it.
Jul 01, 2021, 12:18 PM
Roj
Roj
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Quote:
Originally Posted by JimboPilotFL
It is hard to judge the airspeed of a model airplane going down-wind. It is easy to mis-judge the planes airspeed before making that final turn to line up with the runway. It might seem like it is flying fast enough but because it is going with the wind the actual air speed of the plane is very slow. It is a very common occurrence for a plane to stall in that situation and you should be familiar with that if you fly models. It is a matter of perspective from where the pilot is. It is not the airplane it is the pilot on the ground.
I agree its hard to judge airspeed from the ground, but isn't what you are describing (turning 180 degrees to line up with the runway) an upwind turn?

By your logic, airspeed should increase when turning 180 degrees to face the wind to line up the runway.
Of-course, in reality, airspeed doesn't change at all in a plane flying in equilibrium - in any turn - regardless of wind.

Sorry to see this beautiful plane destroyed.
Jul 01, 2021, 01:43 PM
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JimboPilotFL's Avatar
Quote:
Originally Posted by Roj
I agree its hard to judge airspeed from the ground, but isn't what you are describing (turning 180 degrees to line up with the runway) an upwind turn?

By your logic, airspeed should increase when turning 180 degrees to face the wind to line up the runway.
Of-course, in reality, airspeed doesn't change at all in a plane flying in equilibrium - in any turn - regardless of wind.

Sorry to see this beautiful plane destroyed.
I don't think so. When you are going down wind you are on the downwind leg of an approach. When you turn 90 degrees you are making a downwind turn and you are then on the base leg. When you turn 90 degrees more you are on final approach. But then I am not a pilot and I only know what I have hear over the years at the field and what I have read in many model magazines.

edit to add: I think they use the same terminology in sailing. You make downwind turn when you are going downwind and you make an upwind turn when you are going upwind.
Last edited by JimboPilotFL; Jul 02, 2021 at 09:52 AM.
Jul 20, 2021, 02:51 PM
Registered User
This was undoubtedly a spin, not a spiral-dive. The port wing was fully stalled. The difference between the two is that elevator and aileron authority is retained in the spiral dive, but not in the spin (ailerons). If I had to guess, the motor on this model rotates to the right as viewed by the "pilot" were one sitting in the model. The slow-speed high-angle of attack can accentuate the torque reaction from the prop, causing yaw, and therefore precipitating the spin entry. Being a "power on spin entry", the departure from normal flight approaching the stall to a full in spin condition is both rapid and fairly violent.

The advice to learn as much as possible about full-size aircraft aerodyamics is sensible. Most flying clubs have copies of such books, and a flight or two with an instructor to do some spin-training might also help you get your head around it. Bad luck, was a nice model!
Jul 22, 2021, 12:06 PM
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in a 45deg banked turn there is 1.5g and stall speed is multiplied by 1.5 .
in a 60deg , 2g and double stall speed .
its a shame to see the dauntless go .
Jul 27, 2021, 04:51 AM
Registered User
Think of wind as a river, it helps someone realize how little ground speed means. In a turn your wings are developing less lift because some of the energy that would have been lift, is to the side.

I have never ever stalled a full scale plane unless I did it on purpose, you have an air speed indicator to keep from doing that and you never pay attention to ground speed. With RC, its a different story, we can only see ground speed and have to take the change in wind into account to figure out if we are flying fine, or about to stall. With RC I have stalled more planes than I want to think about


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