Principles #3 - Left Turning Tendencies
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- เผยแพร่เมื่อ 28 ส.ค. 2024
- This lesson teaches what the four left turning tendencies are, their effects on an airplane, and how to counter them so you can take off safely and keep flying coordinated to increase your airplane's performance.
An airplane with a propeller rotating clockwise is used to demonstrate, so if your airplane's propeller rotates counter clockwise then you will experience RIGHT turning tendencies.
Comments and feedback are always welcome, so if this video helped you out hit the like button and let me know in the comments below. Cheers!
EXCELLENT TUTORIAL: I have seen these forces mislabeled and/or mis-explained more often than not over the last 40+ years, by novices and professionals alike. I have never seen such a concise and accurate description as the above video, and IMO anyone reading this comment should subscribe to this channel. This guy is the real deal.
Thanks Heydonray, I taught my own students this stuff of course and I've always tried to ensure what I present is correct. Primacy is real! My videos are reviewed as well before a public release to catch anything that needs attention. I appreciate that you enjoyed what I made very much as they take plenty of time to do right :-)
@@RequiemsACTL The time you spend is obvious! Again, well done sir.
OMG, this is so good. Mysterious flight behavior is now starting to make sense!
Another keeper. Concerning prop effects: Now that I know why and when they happen, I'm am better able to do the right thing at the right time. This is specially useful when I'm learning a new aircraft. Muchas garcias.
Excellent to hear Gustaf! The easier it is for you to fly the plane, the more focus you can spend on the bad guy to shoot him down :-)
Thx, this explains a lot of some of my problems in IL-2 1946!
No worries D MO, very glad to hear it's helped you learn something!
Taxiing I always have Dead Or Alive - you spin me right round in my ear!
Hopefully not anymore :-P
You're a legend, sir! Your tutorials are gold!
Cheers Sarge!
Another great video, thank you for your efforts, it’s appreciated
Thanks John, this video was a good example of how you can use a sim to show certain aspects of flying without worrying about the crashing aspect haha
Your video's should be part of the game...
Thanks for the video, you're a life-saver.
Thanks a lot. It help me to put word on things I "knew" with experience. It's great when knowledge meet experience.
That's what I try and do! A lot of sim pilots know how to things work intuitively through a lot of practice and experience, so I can help with that now to bridge that gap in a similar way as if you guys were my own flight students. Although, obviously I make some adjustments because none of you are in a real airplane with me! LOL
Free Pilot University, Kudos!!
Much, much better. Thank you very much.
Thanks again for bringing the audio issue to my attention quickly so I can send out a "hotfix" :-)
Excellent stuff as usual, Requiem!
Thanks Vlcoun, appreciate your opinion as always!
Thank you Sir!
This makes this game so good. In reality the bf109 was also a tricky plane in take off and landing.
Yeah I chose the 109 for this video as I knew I could illustrate each point about Left Turning tendencies pretty clearly. The 109 isn't so bad once you get the hang of it, but I can definitely see how new pilots would have been crashing them on takeoff and landing.
Thank you, buddy!
No worries!
grazie del lavoro fatto
While watching i had the thought..would you take this into account while trying to evade an enemy? say roll left in a 109 rather then right?
Hi Finn, you could do that of course but keep in mind that the lower the speed the more pronounced the effect would get.
I'm pretty sure a ww2 pilot said that in a mustang the turn would be better to the right (is 109) this would be the cause of that "less ability" to turn right (already many forces requiring right input anyway?) Yes?
Hi Shannon, all pilot anecdotes depend on the context...
I believe that the Mustang's propeller rotates clockwise (same as the 109) so I don't know how true that is to compare the effects between them. I've never flown warbirds, maybe one day in the distant future, let alone a P-51 and 109 for a comparision! :-)
How the different forces interact in left or right turning tendencies give us the impetus for the Learning of a proper rudder Usage .
But in the heat of a dogfight , how is one supposed to maintain similar coordinated turns and rudder usage ? Is the procedure similar or altogether a different approach is needed ?
With practice you get a feel for how much rudder you need, but you can check the slip indicator to be sure. In a real airplane you can actually feel if you're uncoordinated so it's easier to fix.
Love your vids, would you recommend keeping the plane coordinated during a climb aswell or does additional drag not make it worth it?
Always keep your plane coordinated in a climb. An exception to wanting to be coordinated is in a descent for example, by doing a slip during a descent you can actually descend faster without gaining the extra airspeed due to the extra drag added by flying uncoordinated.
Thank you, I thought the additional rudder to keep it coordinated might hurt the climb performance ^^
didnt get precession, can someone link me something to help me understand ?
I assume on IL2 like other simulators this can be countered even before starting take off by adjusting the Yaw, before adding the throttle. This way you do not have to maintain a strong action on the joy stick for yaw, as the yaw is already setup prior.
I suppose you could but I can't imagine taking off in that manner is a good technique. As a flight instructor I would never teach my students to do that in real life, but if you find it works for you in a simulator more power to you. You can of course use rudder trim positions for takeoff but I wouldn't recommend using an actual rudder position before you even start rolling.
The idea is that you use it to keep yourself aligned with the runway and until there is some kind of movement left/right you don't know how much rudder is needed. The combination of throttle setting, airspeed, wind, surface, etc during the takeoff means every takeoff won't be exactly the same so adding rudder before it becomes effective is counter intuitive in my opinion.
Besides, once the above factors start interacting you are going to have to begin adjusting rudder anyway, so you might as well do it smoothly from zero while the takeoff progresses so you develop a good feel for the rudder's effectiveness during the roll.
What would your plan be for rudder use on landing coming to a full stop?
using rudder feels insanely hard with a twist stick, since anytime I apply rudder in the air the whole plane rolls with it, even for knife flight the rudder just levels me out. Leads to me just ignoring the rudder and only rolling which sucks :( cool to see what good rudder usage can do though.
I started out with a twist stick myself and when I moved to rudder pedals that felt really weird, but yeah the twist stick is hard to get used to for sure.
Is there a rudder/yaw trim to cancel out these forces. Because it will be quite impossible to keep the right pressure all the time or even for a short period of time without straining yourself.
There is no rudder trim in the 109, but the consolation to that is once you get up to around 450kmhr you wont need any rudder input to be coordinated
I think that the demonstration starting at 3:10 is incorrect. I'll try to explain why I think so:
When you pitch down to raise the tail, there should indeed be a gyroscopic force yawing the aircraft to the left. The strength of this force is proportional to the rapidity with which you pitch down (as you mention at 3:49).
*HOWEVER*, the gyroscopic force is only applied during pitch _changes_. Once you stop changing your pitch, no more gyroscopic force is applied and yet your aircraft is still clearly experiencing a yaw to the left.
The cause of this continuing left yaw is *NOT* a gyroscopic force. The cause is probably spiral slipstream. By pitching down, the tail is raised higher. Now that the tail is higher, only the top part of the spiral slipstream is impacting the tail. The propeller is rotating clockwise, so this part of the spiral slipstream impacts on the vertical stabilizer on the left side, causing a left yaw (exactly as you described at 1:07).
I also question your assertion earlier in the video at 2:26 that spiral slipstream is causing the aircraft to yaw to the left when the nose is pitched up and throttle is increased from a standstill. In fact, it is possible that spiral slipstream is actually attempting to yaw the aircraft to the right (but is being entirely cancelled out by the much more powerful effect of P-factor). The reason that I think this is because the aircraft is sitting on its tail wheel, pitched up, and so the spiral slipstream cannot flow along the length of the aircraft, but would instead run parallel with the ground. Depending on the shape of the aircraft, this could cause the spiral slipstream to impact the vertical stabilizer more strongly on the right side, causing a right yaw. That said, I'm not familiar enough with the characteristics of the Bf109 to say for sure if I'm correct, and I'm also not sure if IL-2 Great Battles actually models the spiral slipstream hitting the ground in this way. Regardless, the result would still be a left yaw in this situation, because P-factor is just that powerful.
(Thanks for making your instructional videos. Despite my criticism of this particular video, I think your content is extremely valuable, and I refer to it often. I'm only writing this because I watched this video about ten times.)
Thanks for taking the time to compile your feedback Maple, enjoying my content, and to be thinking about these things in addition to what you see here. I had to wait to come home until replying because it's too much to do on a phone. When I was explaining this stuff to my students I could isolate and explain each tendency on a whiteboard individually, but in a sim unfortunately I can't switch off any of these aspects as they will always be interacting at some level, so I tried to choose situations to illustrate each tendency as best as I can with a sim that's always in motion. I'll try to respond as best I can to both of your main points.
1. In the gyroscopic demo I would put down the yaw which continues briefly (at a much lower rate of acceleration) after the tail has stopped being raised due to momentum plus the other tendencies as you have mentioned. You're correct in what you're saying but this extra bit of yaw after the tail has stopped being raised is not what I'm referring to when I'm talking about precession. I am talking about the majority of the yaw experienced in that demonstration while the tail is being raised, which is due to precession.
2. You've actually presented a contradiction by saying that spiral slipstream will make the aircraft yaw to the right when earlier you say it will make the airplane yaw to the left. The Bf 109's shape does not change so spiral slipstream cannot cause both a left and right yaw because the Bf 109's propeller rotation direction does not change either between demonstrations. If a propeller rotates clockwise (as it does in a Bf 109) it will always move along with the airplane's fuselage and strike the left side of the vertical stabiliser, causing left yaw. If the propeller rotated counter-clockwise it would have the opposite effect. This is why in some Russian planes which use counter-clockwise rotating props you need left rudder on takeoff instead of right rudder like in a Bf 109 due to the opposite turning tendencies. The propeller is creating the spiral slipstream by forcing air backwards in the opposite direction of the thrust created, so think of the air as a rotating cylinder parallel with the fuselage when you apply the thrust. No matter where you move the cylinder along the fuselage it's rotation will always strike the left side of the vertical stabiliser (if the propeller is rotating clockwise). Because of the propeller's rotation it also imparts that twisting motion of the slipstream along the fuselage (not the ground) and will be more pronounced when the propellers are at higher angles of attack/slower airspeeds than when they are in cruise flight for example.
As a thought experiment, but before you read the document below...imagine the propeller still rotating clockwise...but the vertical stabiliser was designed to be below the fuselage instead of above. Do you think spiral slipstream would produce a yaw to the left or right?
Stick and Rudder is a great book to get more detailed explanations on the topic that are easy to understand archive.org/details/StickAndRudderAnExplanationOfTheArtOfFlying
@@RequiemsACTL
Thanks for taking the time to reply.
> this extra bit of yaw after the tail has stopped being raised is not what I'm referring to when I'm talking about precession.
Ah, OK, I get you.
> The Bf 109's shape does not change so spiral slipstream cannot cause both a left and right yaw because the Bf 109's propeller rotation direction does not change either between demonstrations.
Yes, but couldn't the path that the spiral slipstream takes over the fuselage change depending on whether the aircraft is sitting on the ground with its nose up, or parallel with the ground during a takeoff run? If the ground is close to the vertical stabilizer, like on a taildragger resting on all three wheels, couldn't that squash the spiral slipstream upwards, and result in a different part of the slipstream hitting the vertical stabilizer?
> think of the air as a rotating cylinder parallel with the fuselage when you apply the thrust. No matter where you move the cylinder along the fuselage it's rotation will always strike the left side of the vertical stabiliser (if the propeller is rotating clockwise).
The air at the top of the cylinder will indeed strike the left side of the vertical stabilizer as it rotates clockwise. I do not contest that the top of the cylinder is the part of the spiral slipstream that is in line with the vertical stabilizer in normal situations. However, with a taildragger like the Bf109, is it not true that the presence of the ground could push the spiral slipstream upward, and so a right hand yaw could be induced if the aircraft was the correct shape? Or at the very least, a diminished left hand yaw? This page is about model aircraft, but mentions the possibility: www.dwave.net/~bkling/rc/howto/propefct.htm
> As a thought experiment, but before you read the document below...imagine the propeller still rotating clockwise...but the vertical stabiliser was designed to be below the fuselage instead of above. Do you think spiral slipstream would produce a yaw to the left or right?
Before reading the document, I would say that I would expect a yaw to the right in this case of a below-fuselage vertical stabilizer with a clockwise rotating prop, as the spiral slipstream would impact the vertical stabilizer on the right hand side.
I read the part of the document that I believe deals with the subject (Chapter 8, The Thing Called Torque), but I can't find anything to suggest my initial answer was incorrect.
Unless I've completely misunderstood, I suppose there's only really one point of contention here: Is it possible for the spiral slipstream to follow a slightly different path in the close presence of the ground? And is this actually likely in the specific case of this Bf109?
Edit: broken link
I
m very sorry for the late reply on this Maple as I didn't see it posted. Seems like TH-cam automatically prevented it being posted due to the link in your comment. I see what you're getting at now regarding the slipstream causing a a possible yaw reversal when the tailwheel is on the ground from that page, but that is something I haven't heard of before. The only way I can visualise that happening is if the wash striking the lower part of the vertical stabiliser which extends below the horizontal stabiliser is stronger than any wash striking the upper vertical stabiliser could you possibly see that happening. I don't know the true answer here though, so I'd have to ask around and see what I can find out about it and get back to you.
@@RequiemsACTL No worries, thanks for the replies, and thanks again for making these great videos. If I ever find out anything more on this subject, I'll post it here.
Do you use TrackIR or is there something better?
I used to use the hat switches to look around but I find TrackIR is much more immersive. I don't have the GPU capability to run Virtual Reality otherwise I would probably give that a go! I've heard it's pretty awesome.
Yeah imagine it will be but TrackIR will suffice for now--wish there was a cheaper version though.
There are a few options out there other than TrackIR. FreeTrack, FaceTrackNoIR, and Trackhat come to mind but I don't use them so I can't guarantee it will work with IL-2.
Cheers, will get TrackIR to save hassle.
Is this DCS world?
It's the Il-2 Sturmovik "Great Battles" series
Maybe it's me, but the video becomes corrupted at second 10.
Just checked it. No problem watching it on my end.
@@RequiemsACTL Then it's me, but I've tried in 3 different browsers and after the second 10 the image turns green and distorted, the audio goes fine. Anyway, great videos!