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Old Mar 06, 2010, 03:58 PM
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Beginners Flight School Videos

I'm doing some Beginners Flight School videos for the RCPowers forum. I thought some of you might find them helpful as well. I have a write up for each video on the RCPowers forum. The video titles link to the write ups.

Video 1: Beginner's First Flight

Beginner flight school - First Flight (4 min 52 sec)



Video 2: Circling Decent to Landing


RC Hawk Sky Circling Decent to Landing (2 min 14 sec)


Video 3: Stalls


Beginners Flight School - Stalls (9 min 45 sec)
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Old Mar 07, 2010, 09:27 AM
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Thanks for sharing! I've definitely taken on board some of your tips.
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Old Mar 08, 2010, 11:56 AM
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Thanks for sharing! I've definitely taken on board some of your tips.

Thank you for the kind words Munce. I'll keep making videos for topics that folks are interested in.
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Old Mar 08, 2010, 12:14 PM
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Very informative and helpful videos.
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Old Mar 08, 2010, 02:00 PM
Off we go.............
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Not bad but I dont think the flat foamie was a good demonstator of a stall. IN fact I never really saw it do so.
These type of planes violate too many of the normal rules of flight to be good for this sort of thing.
A true full stall will have the plane literally stop, then drop it's nose and dive. And at that point the pilot should do nothing, but wait till the plane dives out and gets it's airspeed back. Cause thats what it's designed to do, and will if you let it.

But the good thing is whats said about the stall, thats it all about AoA. And that, is always completely in the pilot's hands with his elevator stick.

As I have always preached, "The airplane cannot stall, only the pilot can do this."
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Old Mar 08, 2010, 06:16 PM
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Airspeed direction relative to a wing is angle of attack. Wings don't generate lift if there isn't any air moving over them. But why complicate things with technicalities?

Nice videos though. Keep up the good work.
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Old Mar 09, 2010, 09:20 AM
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Originally Posted by SabreHawk View Post
Not bad
Thanks for watching my videos Sabre. I appreciate you taking the time to leave feedback as well.

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Originally Posted by SabreHawk View Post
I dont think the flat foamie was a good demonstator of a stall. IN fact I never really saw it do so.
One of the reasons for using both the foamy and the Hawk Sky was the dramatic difference in how they react to a stall. The foamy also enabled me to show how addition of power can further destabilize a stalled airplane. The Hawk Sky is far to unstable in a stall to enable me to demonstrate that with my piloting skills.

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Originally Posted by SabreHawk View Post
These type of planes violate too many of the normal rules of flight ...
This is a common misconception about foamies. They cannot violate the rules of flight anymore than I can violate the rules of gravity. They can be very good, though, at showing how the rules of flight apply to differing airfoil designs.

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Originally Posted by SabreHawk View Post
A true full stall will have the plane literally stop, then drop it's nose and dive.
A stall doesn't have to include the plane 'stopping'. In fact, only stalls that include a high pitch attitude will resemble this. The Hawk Sky doesn't stop in most of the stalls I demonstrate. The extreme dive in the Hawk Sky is more a factor of its instability during a stall and the rapid induction of a spin.

I have flow full scale planes that also stall fairly level. The Piper Cherokee I used to fly would stay level and 'rock forward and back' during a stall. The high wing Cessna's I flew exhibited the more recognizable nose down pitch type stall.

Different airframes can exhibit wildly differing visual stall characteristics.

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... at that point the pilot should do nothing, but wait till the plane dives ut and gets it's airspeed back.
I completely agree that once a pilot reduces the angle of attack, they don't have to do anything else (apart from obstacle avoidance). However, a dive and increase of airspeed are generally not required. During flight training, I was always scolded for allowing the plane to 'dive and accelerate'. Once the stall is broken, the plane can usually be immediately pitched to the horizon.

Airspeed is not necessarily required to recover. If you look at the stall recovery at 5:53, you'll notice that the plane is flying straight up with very low airspeed when I recover. The reason the plane is not stalled is because of angle of attack, not increased airspeed. This is possible in this attitude because of the extremely low wing loading (practically zero).

Thanks again SabreHawk for watching and commenting on my video. I hope this provides further explanation to you and others about what is happening during stalls.
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Old Mar 09, 2010, 11:36 AM
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Originally Posted by Wrend View Post
Airspeed direction relative to a wing is angle of attack. Wings don't generate lift if there isn't any air moving over them. But why complicate things with technicalities?

Nice videos though. Keep up the good work.
Thanks for the compliment Wrend. I really appreciate that.

I like how you defined Angle of Attack. Angle of Attack is all about direction of travel compared to the angle of the wing. This can be a hard concept for some folks to visualize.

I want to piggyback on the comment you made about wings needing airflow to generate lift. A wing that is not generating lift is not necessarily stalled. At 5:53 in my stalls video, I break the stall while the plane is vertical. It slows and executes a hammerhead turn (all by itself I might add). During this maneuver, the wing is generating almost no lift at all, but it is not stalled. Why doesn't it stall here? The wing load is also very close to zero, and angle of attack is directly related to wing load vs. lift. Airspeed is not necessarily required to keep a wing from stalling. Conversely, as wing load increases (as it does in high G maneuvering), the wing can stall at a much higher airspeed than normal. High airspeed is not necessarily enough to keep a wing from stalling.

Thanks again for watching my videos and your insightful definition of Angle of Attack. Feel free to drop me a comment about topics you would like covered in the future.
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Old Mar 09, 2010, 02:42 PM
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I have flow full scale planes that also stall fairly level. The Piper Cherokee I used to fly would stay level and 'rock forward and back' during a stall. The high wing Cessna's I flew exhibited the more recognizable nose down pitch type stall.
Yep. Stall does not necessarily 'cause' or require a nose down to recover, but it does need a change in AoA.

In real aircraft with higher and higher wing loadings and momentum due to there size and mass, if you move beyond high wing trainers you will find a proper fully developed stall is a VERY serious situation.

Unlike most sims, and as RC guys know a stall doesn't happen all at the same time along the whole wing or to both wings equally. The shape of the wing plays a huge part but gets wild complicated as to why, but ultimately one wing is usually going to stall before the other. Remember I am talking about a fully developed stall, a break away, the wing is not suddenly producing very little lift but still producing drag. That wing will fall and slow more developing it's stall. At the same time the yaw effect caused by this has propelled the unstalled wing forwarding increasing it's airspeed and increasing it's lift. This process continues with both wings stalled, but one more so than the other and a spin develops.

The problem with a spin, even if you know the recovery, is they often happen at low speed and at low speed with stalling wings you have very little lift (Duh, that's what got you here), but what do you think control surfaces use? Yes lift.

Now most small light aircraft and most large heavy aircraft will recover from a spin, IF they are sufficiently strong to survive the spin.

Heavy small aircraft like fighters with delta wings is a different story. A full developed spin can go flat spin or falling leaf where there is no airflow over the controls and they are mostly useless. The aircraft 'flops' one way, stalls, flops back the other like a floating leaf, usually spinning. There often isn't that much time to 'rock it out'.

So... why did I say "fully developed stall"? Well, it comes down to one question. Are ALL wings stalled? If no, then it's not fully developed and this is the most common stall type people experience 'accidentally' and it's not really a full stall at all, it's a safety feature of the aircraft.

The main wing stalls, the tail does not. Simple. This causes a sudden pitch forward to reduce angle of attack on the main wing and restore flight. It can still enter a spin, especially if provokes with back elevator and rudder, flaps, or ailerons are unwise too.

Aircraft that stall level are risking entering a proper fully developed stall and the spin that will come from it. Be careful.

You get all kinds of other stuff, tips stalls etc. High speed stalls, high speed spins.

Paul
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Old Mar 11, 2010, 07:09 PM
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Hey Venquessa.

Those are fantastic points. Thanks for sharing your wealth of knowledge about stalls.

I hope you will continue to look in on my future videos and share your understanding of these flight concepts.

Thanks!
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