cappaj1

My Feedback: (1)

I don't yet have a real plane, so can someone please explain what a stall is and how I would duplicate one using the G4 simulator, ie. what I have to do, and with what plane, that would give me an example of a stall.

Does the engine actually ever stall out or is it just a term for trying to gain altitude to quickly where the plane takes a temporary dive?

I'm practicing with a Sig Kadet PT40 and when I try to fly straight up, full throttle, the plane gets to a point where it sort of stops, then GRADUALLY levels out to straight and level flight. It doesn't feel like a stall.

Also, on landing, if I cut the throttle all the way down and try and lift the nose too quickly while descending, it sort of drops a little, but nothing drastically. It sounds like a stall is more drastic from the terms I've read in some of the threads where the nose drops like a rock. I can't get that to happen.

Please help explain and tell me how I can cause one. Thanks.

RCKen

My Feedback: (9)

Actually, a stall means that the wing has stopped producing lift. Air flowing over the wing produces the lift that is needed for the plane to fly. When the air flowing over the wing reduces to the point that there isn't enough lift generated to overcome the weight of the plane the plane "stalls", and will start falling uncontrolled. If the plane goes nose down and enough lift is generated the plane can then start flying again. This is why a "stall" at a low altitude is usually a killer. There just isn't enough altitude to get the wings producing lift.

Does that help?

Ken

RaceCraftRC

I may can help, the nose drop is a stall, ( nose stall from vertical flight) gravity just catches up with. Tip stall is when a wing will drop, usually caused from a lack of air speed ( more as a lack of lift from the airfoil) , You will notice that some planes like trainer are very hard to stall , my PTS will slow to a crawl and just do a very light drop, about a foot than its back again. However some planes are very prone to stalling at slow speed's , Has you progress in your RC career at some point you will end up with a war bird, there high wing loading and scale like airfoils make them very prone to stalls that can be very tricky to slow down without stalling ( flaps help tons). Hope this helps and I didn't make it worse, good luck.

cappaj1

My Feedback: (1)

Yes, that helps explain what it technically is, and I appreciate it, but I'm not sure if it's just that the simulator doesn't re-create a stall accurately or if the plane I'm choosing has too beefy a motor or maybe if trainers don't exhibit stall as easily but I can't seem to duplicate it. The closest I think I'm coming to a stall is when I'm landing with the throttle set all the way down or close to it and when very close to the ground, if I try and pull back the stick too quickly the plane sort of drops and 'bounces' on the runway. Is that likely a stall?

RCKen

My Feedback: (9)

To clarify what a tip stall is. This is where the tip of the wing stalls first, and this the plane will fall to that side.

Yes, you can stall a plane in a simulator. Simply kill the engine and try to hold level flight as long as possible, or even a little bit of up elevator with no power. When the plane no longer has the airspeed to fly it will fall. Pretty simple.

Ken

combatpigg

My Feedback: (3)

Expect a lot of long winded answers.
A wing needs X amount of airflowing past it to create X amount of lift. Without enough lift, it stalls......and will not start creating adequate lift [to support the load] until enough airflow is reestablished. Take a moment to consider all the different scenarios that could contribute to not enough airflowing past the wing to maintain flight......from what you already know about how things work.
Remember that weight and gravity are enemies of lift, as well as lack of airspeed.
When forced to fly through the air with the wing tilted up, more airflow is required to generate the same amount of lift compared to flying level. So an easy way to make a wing stall is to point the nose of the plane up too far without enough airflow past it.
This is what makes flying slowly downwind treacherous with some [overweight] models.

Jetdesign

My Feedback: (8)

I just went through something similar to this. I understood what a stall meant, but never really thought I experienced one. Two weeks or so ago, I experienced a 'hit' when turning in to final. (I was told I was landing my plane too fast, so was practicing coming in really slow.) I freaked out, nailed the throttle, and aborted the landing, deciding to land in the other direction (with the wind). It happened again a week ago, turning in to final again. My plane rolled over, turned itself around, and started flying the other direction, uncontrollably. I was told there's 'a bunch of noise' in that general area, and that some of the 72mhz guys get hit there.

Last week I was practicing slow flight, and just for kicks, dropped it all the way to idle on a downwind leg. Guess what? The plane drastically rolled over, and started to turn itself around. I realized I was stalling on the turns to final, due to lack of power and changing wind conditions. In my case, flying that slow and making a turn, one wing is moving faster than the other one, and the slow wing was going so slow it lost it's ability to create lift, so it dropped straight down. The wing with a little speed kept moving forward, pivoting around the stalled wingtip, causing the plane to turn around.

A (tip) stall was later explained to me like your plane is sitting on top of a big ball and starts to roll over the side. Like Ken said, it's failure to create lift. Some planes do it easier than others (tapered wings, symmetrical wings, etc). You can try a different plane on your sim and fly it at idle speed and make some turns, and see what happens. I never noticed it with the Nexstar, possibly due to it's large, flat bottom wings, or due to it's tremendous dihedral (may have stalled but just mushed forward like trainers are supposed to do).

There was a thread about slow flight practice, and this is why it's recommended. After practicing that, I know how many clicks of throttle I need in different wind conditions to keep my plane flying (able to make turns, etc: 2 for no wind, 3 for light wind, more for heavier wind). Also I know when/where to bleed off speed.

Hope this helps.

cappaj1

My Feedback: (1)

I just tried that with the PT40 - ascended to 200 feet, killed the engine, and tried to hold level flight and all that happens is the plane glides down slowly, as peaceful as a bird and lands smoothly on the ground.

Maybe the trainer just doesn't stall. I really think I need to try another plane to see something a little more realistic, ie. drastic.

RCKen

My Feedback: (9)

As I said, you may have to add in some up elevator. Some planes do have a very gentle stall characteristics. The Sig Rascal I reviewed would simply dip the nose and then start flying again. Other planes will have ugly stalls that are very difficult to recover from.

Ken

cappaj1

My Feedback: (1)

I think you're dead on when you say that's what trainers are supposed to do. All I can get the trainer to do is 'mush forward' as you say. Maybe that's a stall in the trainer. I sure would like to find a plane on the sim where the nose 'drops like a rock' like I've read on so many threads it seems.

cappaj1

My Feedback: (1)

Ken, I'm not trying to be a wise guy and I really appreciate your taking the time to answer me, but believe me when I say I pulled back on the stick all the way till it wouldn't go any further and it still glides down like a bird. I think it's the trainer.

RCKen

My Feedback: (9)

Yes, but you are also talking about a simulator. Trust me when I say that it is possible to stall a trainer. But like I said earlier, every plane has different stall characteristics.

Ken

cappaj1

My Feedback: (1)

I just tried what you suggested, Ken, flying a B-17, figuring with all that weight and four engines to get it airborne if I killed all four maybe I'd get something that felt like a real stall, and sure enough, it started out gliding smoothly with the stick all the way back eventually, but then about 20-30 feet above the runway, just dropped like a rock as they say.

cappaj1

My Feedback: (1)

Just tried it with a Yak-54 and finally I got something that gives me an idea of what a real stall is. Flew to 100 feet, killed the engine, tried to keep it straight and level and even with the stick pulled back it drops like a rock, and seems to do some wing stalls as well - just guessing.

Jetdesign

My Feedback: (8)

Try to make the plane stall by turning when you're flying without power, and see if you can get a tip stall.

foosball_movie

FYI.

I stall is created whenever the critical angle of attack is exceeded. The critical angle is the chord line in relation to the relative wind. A wing can stall at any airspeed. If the critical angle is exceeded, there is a seperation of wind over the surface of the wing.

Nathan King

This thread can not be complete without mentioning one additional point. To say a wing (airfoil) stalls because of inadequate speed and/or too much pitch up is misleading and doesn't cover all bases. The only way to stall an airplane is to increase the [link=http://www.centennialofflight.gov/essay/Dictionary/angle_of_attack/DI5.htm]angle of attack[/link] beyond the critical point. This critical point, or angle, is different for every aircraft.

Therefore, you could have an airspeed of 100 miles per hour and still stall. You could also point the airplane nearly straight up and not stall.

P.S. I am not picking on anybody or claiming anybody is wrong or stupid. My only goal is to provide the most definitive answer possible.


Now, not every stall is going to cause the aircraft to respond the same way. How the aircraft responds to the stall depends on the circumstances leading up to it. Keep in mind the following sentences are generalizations. Trainers will simply nose down fairly gradually and bring themselves out of the stall quickly. More aerobatic aircraft typically nose down more quickly than a trainer and take a little more altitude to get out of the stall, assuming the airplane was in coordinated flight as it stalled. Aerobatic aircraft not in coordinated flight at the time of a stall will likely drop a wing and begin to spin if not immediately corrected. This is because one wing stalls slightly before the other. If you ever find yourself in a spin, remember the acronym PARE.

Power down
Ailerons neutral
Rudder applied in opposite direction of the spin
Elevator gently pulled to straight and level flight

If anything, just remember not to use your ailerons to correct a wing dip from a stall. Using the ailerons to correct can actually make a stall worse for reasons beyond the scope of this forum.

Have fun!
Nathan

Nathan King

Bah! By the time I finish writing my posts somebody else has already brought the topic up!

foosball_movie

Too slow!!!

Also, it may be necessary to "break" the stall by aggressively pushing down elevator.

cappaj1

My Feedback: (1)

Thank you guys, and I think I have a better understanding of stalls now.

In my humble opinion, the little quick bounce ie. drop to the runway when landing if I have the throttle set very low and pull back on the stick a little too much is a stall in the trainer. It's just not that drastic because it IS a trainer.

I'm also of the opinion that the sim, even with the wind and turbulance turned on, isn't accurately projecting the real feeling of a stall as if it were a real rc trainer.

I'd be willing to bet also, although I'm sure I'll get disagreement on this one, that the stall characteristics of scale aircraft doesn't reflect the severity of what a stall would be in a full scale airplane.

Thanks again for all the explanations and if anyone knows of a good airplane to try in G4 that exhibits stalls more drastically than most, please let me know, as I'd like to practice a little before I get a real scale airplane.

Nathan King

This statement is true. I fly full scale aircraft, and I can tell you that the consequences of a stall in a full scale aircraft are much more severe than even a heavy scale model aircraft. The power to weight ratio of a full scale aircraft is much lower than any R/C model.

cappaj1

My Feedback: (1)

Okay, here's my next question in regards to stalls - how to handle them.

If the engine dies while I'm flying straight and level at say 100 feet up and I try and keep altitude by pulling back on the stick, I get a series of dives or stalls, so how do I prevent these dips if I want to glide in for a safe landing, by pushing the plane down instead and gaining some airspeed and then gradually glide into a smooth landing?

Or am I way off track?

Jetdesign

My Feedback: (8)

Keep the nose pitched down to maintain air speed. Trainers, especially, will want to climb with speed. That combination will keep you gliding without losing too much altitude.

foosball_movie

Unfortunately, I don't believe RC aircraft come with published V-speeds. In a full size aircraft, the pilot would pitch for a Best-Glide airspeed. This would give the pilot the most time and distance in which to reach a suitable landing spot.

In RC, it's essentially the same thing. Pitch the aircraft to give yourself a decent airspeed and try to achieve a nice decent angle into the wind for a reasonable landing.

MinnFlyer

My Feedback: (4)

Take a model airplane up in a hot air balloon.

At 500 ft, hold the airplane level (No engine running) and drop it.

Does it fly? No, it drops straight down because it doesn't have air flowing over the wings.

Now if the airplane is balanced properly, its nose will drop, it will gain airspeed and start to recover - or at the very least, it will start to respond to control input. But until it has reached a FORWARD speed greater than its stall speed it will not "FLY" it will just drop.

So how fast is the stall speed? It is different with every plane depending on its wing area, airfoil and weight.

Every airplane has this magic number called a "Stall Speed" - if you go slower than the stall speed, the plane stops flying. Some do a gentile mush, and some will snap violently and drop out of the sky.