The P-51 Mustang had this issue - My dad, a former USAF pilot, told the joke about how you could tell who was a Mustang pilot by the size of their right foot because they had to always use it to counteract these issues.
The large diameter prop, short wingspan and high horse power engine made that plane a real handful. My boss owned one and after a ground accident where he destroyed a helicopter he could not see while taxiing, he had to sell it. The buyer underestimated the need for right rudder and on his first flight he crashed it on takeoff.
Short, informative, no unnecessary blabbering, straight to the point. Words alone can’t describe how much I appreciate this video. In a platform full of creators that strive to make money rather than to deliver, this video truly is a gem
@flight-club I'm a student pilot and have watched a ton of videos trying to grasp p factor (I bought Sporty's ground videos and watched many others). Yours is the only one I've seen that throws out the small detail that made it click: the plane flies with a slight nose up attitude. Thank you! You have a new subscriber.
Italian fighter aircraft during WWII had a unique way of compensating for torque and P Factor - the left wing was slightly longer than the right wing, generating a bit more lift. There was one other weird thing about Italian military aircraft. To advance the throttle, you pull BACK on the throttle, not forward. Only the Italians and sometimes the French did this....
@@larsrons7937 unrelated but fun fact: “They’re nuts those Romans” in italian is “Sono pazzi questi Romani”, and if you take the first letter of each word, you get SPQR.
Most light aircraft are built with no offset (Cessna, etc) Pilots use control surfaces and trim surfaces to offset thrust affects during climb, descent or cruise. Aircraft generally spend 95% of the time in level cruise where the thrust effects are minimal. Very high performance aircraft have a very high cruise/stall speed ratio and should not compromise efficient cruise for eccentricities that occur during 5% of the flight that can easily be accomodatee by pilot control input (primarily rudder).
I always thought it was just because of torque and felt smart about it. I had no clue about the other effects. The blade pitch i can see but the slipstream seems like an insane effect to figure out. Thanks for educating me!
I am a mechanical engineer and I was always passionate about aeronautics. This channel is a great way to expand the knowledge which my aerodynamics course missed.
I'm 65 years old and in all that time, with my interest in aviation, I NEVER ever, knew of this fact. I never heard nor read of it anywhere. And I always wondered how the yaw was dealt with. Amazing! You learn something new every day! 👍😄
@@CramcrumBrewbringer O_O ??? Aka P-Factor, it should be taught/mentioned in the PPL Book. At least a couple to few pages talking about it. Australia does have it in the PPL Book, so I'm curious which country are you in. Edit: everything said in the video is mentioned in the PPL Book (book contains some other info in this regard too).
This setup depends on which way the propellor rotates, this was very noticeable on Merlin engined Spitfires compared to the Griffon engined variants. The engines rotated in the opposite direction.
@@aeroflopper I'm not sure on the two aircraft mention, as to which direction the prop turns, however there is no reason you can't make a prop that will work in the opposite direction. As for the "gearbox", the easiest design is just a smaller gear driving a larger one on the same center line as the engine, this will cause the prop to turn the opposite direction the engine is turning.
I had a VW auto engine conversion in my experimental airplane, it turned the opposite of the other airplanes I trained in. I made no conscious effort to deal with the difference as there were many other things to worry about!
This is also why the island on carriers are on the starboard side, in the early days of carrier aviation, when a pilot jammed the throttle to the firewall on landing in case of a missed wire, the plane tended to pull to the port. So the island was built on the starboard side, preventing a pilot from attempting to park his bird in the CO's stateroom.
Akagi and Hiryū were the only two carriers ever built with the island on the port side. This was intended to spread out the landing pattern during multi-carrier operations.
Pretty much. As the transition from piston engined plane to all jet took the span of decades, by the time the last piston plane left the service the Nimitz class were already in commission so changing a class so drastically (the island off balances the ship so the layout of her ballast tanks and machinery is such to off set it, so just moving it to the other side wont work) and retraining the muscle memory of all the pilots didn't make sense, so it stayed on the starboard (right side facing the ship from the stern). This was all required knowledge for the Enlisted Surface Warfare Specialist (ESWS, abbreviated as (SW) after an enlisted persons rate/rank in the case of me it was MM1 (SW) McIlhinney.
I did R/C model airplanes for many years. All of them needed a little prop offset. More recently I had a 37’ sailboat with a 50hp Diesel engine. The crankshaft angle was between 15 and 17 degrees. Going forward was OK, but, holy cow, was there an incredible prop walk in reverse that moved the stern to the right. Unfortunately our slip needed the prop walk to be exactly the opposite. We wound up wrestling the boat into the slip with brute force.
I studied aero engineering because the RC aircraft I designed didn't fly well, prop offset or otherwise. I also have a sail boat. The angle of the prop has very little to do with it. Do you have a foldable prop? most boats I've owned sail like a pig when motored backwards and prop walk only works one way. I'm in a tidal current berth so it might be different if you didn't need speed against currrent to avoid.
Most model aircraft have to have right thrust and down thrust! Normally 2 to 3 degrees The down thrust is to help on a banked turn to stop the aircraft from rolling in on the turn ! Tried same plane with zero thrust angle and it was a lot more unstable especially on a left turn!
I just stumbled onto your videos. The explanations on both propeller effects and "coffin corner" are two of the most concise and accurate I've seen. Well done.
Love when informational videos are short and too the point. I, just your average Joe, don’t *need* to know the ins and outs, I just *want* a short and simple answer as to why. You learned why and you became a little smarter. If you wanted to dive deeper, then you can find those long and in-depth videos. It’s almost like a gateway drug.
As an RC model pilot I had a thing for twins. I learned that the total torque effect of two engines was no more than that of one engine. Also, I learned to angle both engines out slightly, the right side engine pointed to the right, the left side to the left. This really helped with one engine out situations, as the toeing out of the live engine countered the tendency of that engine to pull to yaw the other way. Designing my own RC aircraft helped me learn about various airfoils, engine thrust, etc, but the most important lesson was to minimize the gap between wing and aileron, elevator and stabilizer, etc. This greatly improved aileron, rudder, elevator authority. Also placing servos as closely to their control surfaces as possible so that control rods were as short as possible, minimizing flexing of the rods. This made the servo to control surface much firmer. Also to avoid all the slop inherent in bellcranks by using two servos for ailerons, one in each wing panel. My planes would groove like a slot car.
For literally decades I have known it was ‘something to do with aerodynamics’ but never really why! Thanks to your short and very easy to comprehend video I now finally understand! Thank you!
Fantastic explanation! I've always thought it's just the torque produced by the engine that would have a noticeable effect, but turns out it's more than that. I'd imagine putting contra-rotating propellers would solve the airflow issues by straightening the airflow that passes through the second set, but it's also noisier and more complex I'd reckon, AND still doesn't completely eliminate the torque from the engine. Guess to show just how much a simple engineering solution could affect the aerodynamic balancing of a single propeller plane.
The genius of the P-38 Lightning is that by having two props each rotating a different direction AND two tail fins, both the torque effect and the aerodynamic effects are incredibly well balanced. A superb aircraft.
@@fubar12345 And if one engine failed, especially at landing and takeoff, the combined drag of the failed engines prop and the torque from the other would cause a lot of crashes... It had a lot of flaws, compressability, poor heating, engines tended to throw conrods etc...
@@fubar12345 You have raised a very good point. Contra rotating props have continued into to modern era. Aircraft such as the Piper Navaho C/R and the Piper Seneca ( Which is still being built) have this feature. The Seneca, especially the later models, are well regarded for their benign engine out handling.
@@zogzog1063 Yes, actually. If the engines are equally reliable and the twin-engined aircraft tends to crash when one engine quits, the single engined aircraft is actually safer, because the likelihood of a crash is lower. Say, for example, that the engine dies on average every 1,000 flights. Statistically, an aircraft equipped with a single engine will experience an engine failure every 1,000 flights, but an aircraft with two of those engines will experience an engine failure every 500 flights. The twin-engined aircraft is only safer if it can safely handle an engine failure.
Love all your videos! As an aspiring instructor your videos have helped with visualising all these concepts and how to better describe them. Keep them coming! I'm interested to see your take on explaining thrust.
This is Real Life Engineer, And I approve this message… 🤣🤣🤣 Excellent video! I haven’t gone into amateur aviation yet. But I was totally fascinated by this video and its explanations.
Great vid. Some light aircraft have the offset achieved by simply having slightly larger engine vibration damper mounts on 1 side to make the offset just as little as 5 degrees. All control surfaces create drag, the more they are moved, therefore it is most desirable to use then as little as possible for trim.
- Yeah well, I also "yaw" when I get sleepy. - Anyway, I've found out that if you replace the plane's control wheel with a leather horse bridle & pull toward right it compensates for the plane's tendency to pull to the left. - Love the background music!
for the last explanation: i think it's more about the dihedral (slight V shaped) wings in front of the center of mass. if you the plane is rotated the wings starts to slightly become L shaped. and since one wing has more surface area towards the ground, when the plane goes down that wing drags more than the other means it will produce rotation and a negative feedback loop. but since the plane has mass that makes it sway towards the "flat" side of the wing. though the wing isn't perfectly at the center of mass so it will produce yaw torque, the engine is tilted slightly inducing torque to counteract that.
dihedral or anhedral don't need to be mentioned, the principal of torque still applies. The relation to the ground only plays into the gravity factor of the aerodynamic equation. Once you put a plane into a bank the aerodynamics change completely so control input is required to correct.
I am around planes often enough. However I have never noticed that before. I will have to start looking when I am around airplanes at work. Thank you for posting.
Great explanation! I think another way to counter this side effect is to offset the propeller axis from the airframe axis, but keeping them paralleled.
Yes, good point! I remember seeing a blurb or something somewhere about a WW2 plane with the question, "Why is the propeller on this plane offset to the right?" This would obviously pull the plane to the left.
These videos are amazing! Keep them coming. In this video - did you forget to mention gyroscopic procession as the 4th left turning tendency? I assume it was omitted because the slightly offset engine doesn't counter that force but it is still good to know that that exists.
Thank you Colin and a great question. My understanding is that gyroscopic precession mainly affects tailwheel type aeroplanes during take off. But you're right, it is an effect worth mentioning so we'll create a video dedicated to it. It is a fairly complex topic to explain.
@@Normal1855 "They" certainly do! I built my kit plane and fly in it with friends frequently i.e. it's not a rc model and I'm a retired commercial and ex military pilot. Many light aircraft of different types have the engine/propeller offset by a degree or two.
@@flightclubonline gyroscopic precession affects every propeller-driven aircraft because, as you maneuver, you force the spinning mass on the front of the plane to change planes. The gyroscopic effect does not change because of the location of the landing gear. Taildraggers exhibit the force more obviously due to the need to raise the tail wheel during the takeoff roll, changing the plane of the spinning mass during the roll itself. Tricycle gear planes are not affected until rotation. Once pitch is changed, it will manifest itself as a force 90° in the direction of rotation. Thus, on a clockwise-turning propeller, when adding upward pitch, gyroscopic precession would induce a yawing moment to the right. Try this with a child's gyroscope initially spinning perpendicular to the ground. Try to angle it upwards. The force it will exert on you will be to the right if it's spinning clockwise, to the left if counterclockwise. Every propeller-driven aircraft is affected by this force. Counter-rotating propellers balance this out, whether they are on the same or separate shafts. It is actually very surprising that you do not have an adequate personal visualization of this as you attempt to explain the forces involved in flight to others.
I knew there was a reason I always gravitated towards twin engine planes. But I'm sure they have their issues as well. Thank you for the easy to digest and direct video. Subscribed.
WHY IS THIS SO GOOD legit thought there was gonna be some faults and misunderstandings, but this is simple yet so explanatory Finally youtube did recommend a good quality video for once
I've the first RC plan and found the motor mount was not straight. My 3-D printed RC plane came with the motor mount model which is not straight as well. These thing lead me to this VDO. Thank you so much!.
Didn't know that. I would get pissed and put a shim or grind it down to make it straight. Then go to the review section and give them a bad review for poor quality control.
Cool , been an A&P for 26 years. Started off on Boeing 727 and other commercial airlines . Work on helicopters now for 16 years there's concepts like this also . Never thought about the angle of attack on a prop plane . Knew about the Tourq effect especially on dual engine planes . Great Video.
That's a beautiful example of how most mathematical models are embedded in a multitude of assumptions. I for myself guessed that it was the off-center weight of a solo pilot in a side by side seating cockpit that would require this tweak of the propeller angle. I was completely wrong, haha
Well, you are somewhat right in your assumption. If the pilot move out on the wing (adding extra weight on only one wing) it would be heavier and this move faster thru the air than the other wing and make the plane go to the opposite direction. Also - the glide angle (lift-drag ratio) of a plane is always the same no matter what the pilot weight - it only travels the glide-distance faster. Gliderpilots often use waterballast to benefit from this.
Hello I'm doing my undergraduate course in aerospace engineering. I love all of your videos and your way of explaining. Can you suggest me some similar resources from where I can get help for my academics?
Not a pilot, just curious: at 1:30, what is the AoA relative to? The arc size in the diagram seems arbitrary. I would have assumed the arc would start perpendicular to the flight path; the propellor AoA difference would still be noticeable if so.
Blade AoA is the angle the chord line of the blade makes with the relative wind. Relative wind is determined by both the blade’s forward velocity and well as its velocity due to rotation. Sum those two vectors and you get a line for the relative wind which can be used to measure the blade AoA. This is definitely a case of a picture being worth a thousand words.
@@Hornet135 And further complicating the matter is the fact that the descending blade has different forward velocity than the ascending blade, since the propeller's plane of rotation is not at right angles to the flight path. (You can see in the picture that the airplane's nose is tilted upwards.) And this difference depends on the airplane's airspeed, the angle the plane of the propeller makes with the relative wind, as well as the rotation speed. Cool stuff.
OMG... You really do Learn every day! If you wouldn't have told I wouldn't have known this my entire life.. Thank you.. Just a little off topic... do airliners rent the engine and seats of large passenger plane?
I have always wondered why prop planes never spun around like the way a helicopter would with its tail rotor broke,fascinating stuff and thanks for this
The P-factor in level flight where the downward blade (right) gets more bite of air than the upward blade is already counteracted by a downward offset thrust angle built into the mounting of the engine. The only time the P-factor is apparent is when pitching up coupled with high power settings
Nice but it’s all wrong. Spiraling slipstream is a myth that has been around since the publishing of ‘Stick and Rudder.’ There is no mathematics or pictures that prove it exists. Torque CANNOT be offset by turning the torque axis in a different direction. Torque causes roll which is offset by the wings and ailerons, once trimmed out it doesn’t cause the plane to turn left. The explanation of P-factor is wrong. Aviation educators throughout time have confused the Source of the P-Factor with the actual Result of P-Factor. The Source of P Factor is the asymmetric thrust across the face of the propeller. That is, in a climb or high AOA, there is more thrust on the downward moving propeller blade, than there is on the upward moving propeller blade. As currently taught, it is this additional right-sided thrust, reacting through the propeller, that pulls the plane to the left. But that same thrust does not act through the same propeller this way. Due to Gyroscopic Precession,) (GP) the applied force at the right propeller results in a reaction 90 degrees to the point of application. So, if the force, applied to the propeller at the 3 o’clock position, then GP will result in a nose up force at the 6 o’clock position. Not a left yaw but nose up! The Result of P-factor is increased airflow down the right side of the aircraft. This higher velocity airflow just didn’t disappear-we’ve just forgotten that it exists, or even discussed it, for decades! We need to start understanding that P-factor is the ASYMMETRIC AIRFLOW DOWN BOTH SIDES OF THE FUSELAGE due to the increased thrust caused by the higher angle of attack of the downward moving blade. It’s this higher velocity air, moving down the right side of the aircraft, causes a higher AOA on the entire right side of the aircraft AND the fin and thus a yaw to the left. The slipstream is not pushing the fin over. The fuselage and fin together generate a yawing moment due to its own effective the angle of attack. Right thrust simply aims this higher velocity air at the far side of the fin and reduces the left yawing tendency.
Thank you, you’ve made some good points. Here are my thoughts about a few: Spiralling slipstream in well documented in just about every aerodynamics book that I’ve come across. I wouldn’t discard this theory just because there isn’t a picture of it somewhere. I’m not sure what you mean by “torque axis”. What this clip tries to explain is that shifting the axis of rotation to the right helps alleviate the symptoms of the torque effect. It does this by the means of a secondary effect of a yaw, which is a roll. Gyroscopic Precession effect is only present as the spin axis changes direction. I’d imagine that if the aircraft was continuously yawing to the left, the gyroscopic precession effect would most certainly have an impact. But that’s not the case, such as in slow flight configuration when the effects mentioned in the video are most significant. Finally, please don’t start off with “nice but it’s all wrong”. It’s a little condescending and unnecessary.
@@flightclubonline there are all sorts of aerodynamics studied about planes and one I don’t recognise is spiral flow around the fuselage.I know Form drag ( parasitic) which is linear flow along the the body . This is covered in many ways in many descriptions and experiments . People thought the moon was cheese till it was proved it was Rock . Id like to see some flow patterns to your theory before I say it’s any part of the truth . As the guy says the use of ailerons covers torque roll , yeah in slower speed it can have its greatest effect that you can easily see . Watch single prop planes landing on an aircraft carrier, they coming in short and novice pilot slams the gas on full .
@@flightclubonline On the contrary, Spiraling slipstream may be mentioned in books, but it is the ONLY performance affecting factor in all of stability and control that does not have a single equation defining it or how to compute and allow for it. I've studied this for 30 years. 23 books on aerodynamics and stability and control in the FAA library in OKC, not a SINGLE ONE quantified it. There isn't a single picture of the spiral on a tufted fuselage. It was Wolfgang Langewiesche’s best guess at explaining what he was experiencing. And everyone has just accepted it ever since. Torque is torque. It ONLY acts around the thrust line of the aircraft. It only causes roll. Offsetting the thrust line does nothing to mitigate the forces or effects of the roll. May be condescending but it got your attention.
@@tomsolinski4151 When riveted aluminum airplanes with some age fly through rain, the water and oxides leave streaks on the outer skin. The streaks generally will originate at rivets, follow the boundary layer airflow for
Oops. Completion of the above reply: The rivet streaks map the slipstream. I saw thousands of such aircraft over a 50 year career. No evidence of spiral slipstream on any of them.
This old pilot was telling me about an inexperienced female pilot that was ferrying fighter planes during WWII. While near the ground she needed to go around, applied full power causing the plane to invert, smacking the ground and killing her.
I always heard that was a problem with the F4U Corsair because the huge propeller put so much torque on the airframe at low speed. They couldn't use full throttle on takeoff, as was common with other planes, because at low speed this would cause the plane to flip over on its back and plow into the ground. A lot of pilots transitioning to the Corsair from other planes were killed or injured this way.
That's torque roll that was common in gear down flaps down situations with powerful prop aircraft when the aircraft could get ahead of the pilot and too much power was applied to reassert control. Inexperienced pilots tended to be the victims as you point out.
I'd never thought of these factors nor did I know some single engine aircrafts' propeller axis is offset. Nice to learn something new every day. Of course the asymmetrical thrust is speed dependent, but airplanes spend most of the time at constant cruise speeds.
So the effect is offset a little and plane becomes more balanced? :) great video, didn't see this :) would be more carefully watching planes from now on :)
Don't take this the wrong way, this is still an absolutely amazing video, but I just like the way she says that they just kinda moved it to the right a little. Implying that there was no specific measurements to calculate the angle or anything, and that the engineers just said "Let's just scoot this to the right a little... "
@@suzukirider9030 It's not the same, but while exploring the blueprints for the WW2 Hawker Hurricane fighter I noticed they'd designed a 1.5 degree offset to port into the rear fin to counteract the clockwise rotation of the prop. Thought it was interesting, as it's not something you'd normally notice.
#4 "Gyroscopic Precession" (A force applied to a rotating body is manifested 90˚ in the direction of rotation from where it's applied. Since there is an upward force , and the propeller is rotating Clockwise the Force being realized is to the Left of the direction the Plane is traveling.)
Gyroscopic precession only happens when the plane of rotation is itself being rotated, ie, when the plane is pitching or yawing. So nothing happens in steady flight. The lift force on the wing has nothing to do with it.
that explains alot. i build a 2-engine bomber in besiege and wondered why it flew so instable. i fixed it by making one engine spinning the different direction and turned the propellers. worked pretty well after that - guess the negative effects countered themselfes from then on.
Remember, by pointing the propeller slightly to the right, this effect is offset a little and the aeroplane becomes more balanced.
Loved it everytime she said that
Bellenced
Remember, by pointing the propellor slightly to the right, this effect is offset a little and the aéroplane becomes more balanced.
That's what she said.
🥃🥃🥃
Whooooooo! She said it again!!!
The P-51 Mustang had this issue - My dad, a former USAF pilot, told the joke about how you could tell who was a Mustang pilot by the size of their right foot because they had to always use it to counteract these issues.
All single engine aircraft have this "issue".
@@unknownuser-pb1io WW II single engine fighters have it a lot worse due to the extreme power though.
Yep, and the engines in Japanese planes rotated their crankshaft in the opposite direction. Depending on who did what, the advantage would shift.
The large diameter prop, short wingspan and high horse power engine made that plane a real handful. My boss owned one and after a ground accident where he destroyed a helicopter he could not see while taxiing, he had to sell it. The buyer underestimated the need for right rudder and on his first flight he crashed it on takeoff.
@@lobsterbark oh okay.
Short, informative, no unnecessary blabbering, straight to the point. Words alone can’t describe how much I appreciate this video. In a platform full of creators that strive to make money rather than to deliver, this video truly is a gem
That’s very kind. Thank you.
@flight-club I'm a student pilot and have watched a ton of videos trying to grasp p factor (I bought Sporty's ground videos and watched many others). Yours is the only one I've seen that throws out the small detail that made it click: the plane flies with a slight nose up attitude.
Thank you! You have a new subscriber.
100% agree
Italian fighter aircraft during WWII had a unique way of compensating for torque and P Factor - the left wing was slightly longer than the right wing, generating a bit more lift. There was one other weird thing about Italian military aircraft. To advance the throttle, you pull BACK on the throttle, not forward. Only the Italians and sometimes the French did this....
Yuck
Makes sense. Which direction do you rotate your motorcycle throttle handle? Towards or away from you?
That makes more sense to me
Asterix would have said "they're nuts those Romans"
@@larsrons7937 unrelated but fun fact: “They’re nuts those Romans” in italian is “Sono pazzi questi Romani”, and if you take the first letter of each word, you get SPQR.
Most light aircraft are built with no offset (Cessna, etc) Pilots use control surfaces and trim surfaces to offset thrust affects during climb, descent or cruise. Aircraft generally spend 95% of the time in level cruise where the thrust effects are minimal. Very high performance aircraft have a very high cruise/stall speed ratio and should not compromise efficient cruise for eccentricities that occur during 5% of the flight that can easily be accomodatee by pilot control input (primarily rudder).
Not true at all! Go look at a Cherokee 180:or better.
@@reltney20 most
I was thinking to myself. Weren't those the purpose of trims? Now i know a little better thanks.
On the small Cessnas, the vertical stabilizer is mounted at an angle to compensate these effects.
The prop on a Piper Cherokee is upside down.
This is a work of art!! One of the best explanations of aviation related content ever made
Wow, thanks!
@@flightclubonline no worries
68 years of airplanes on the brain, every day, and never heard of this. Thank you.
@@rickey5353 Me to 8)
my dead goldfish lowkey could have elaborated some of these concepts a bit more thoroughly
I always thought it was just because of torque and felt smart about it. I had no clue about the other effects. The blade pitch i can see but the slipstream seems like an insane effect to figure out. Thanks for educating me!
Thank you so much.
just like me, glad youtube recommended this to me.
I am a mechanical engineer and I was always passionate about aeronautics. This channel is a great way to expand the knowledge which my aerodynamics course missed.
I'm 65 years old and in all that time, with my interest in aviation, I NEVER ever, knew of this fact. I never heard nor read of it anywhere. And I always wondered how the yaw was dealt with. Amazing! You learn something new every day! 👍😄
Glad you enjoyed it!
@@flightclubonline
Even people I knew who flew never mentioned it!
@@geoben1810 Ive almost got my private pilots license and I didn’t know this either
@@CramcrumBrewbringer O_O ??? Aka P-Factor, it should be taught/mentioned in the PPL Book. At least a couple to few pages talking about it. Australia does have it in the PPL Book, so I'm curious which country are you in.
Edit: everything said in the video is mentioned in the PPL Book (book contains some other info in this regard too).
@@DragonX2X7 yeh I’m Aussie and I’ve seen it in the text books
This setup depends on which way the propellor rotates, this was very noticeable on Merlin engined Spitfires compared to the Griffon engined variants. The engines rotated in the opposite direction.
Thanks, I wanted to make this point as well.
not sure if a prop can spin any other way and pull the vehicle forward, would the gearbox unit not compensate for the engine rotation?
@@aeroflopper I'm not sure on the two aircraft mention, as to which direction the prop turns, however there is no reason you can't make a prop that will work in the opposite direction. As for the "gearbox", the easiest design is just a smaller gear driving a larger one on the same center line as the engine, this will cause the prop to turn the opposite direction the engine is turning.
or the firebrand with a rudder thats facing like, sideways
I had a VW auto engine conversion in my experimental airplane, it turned the opposite of the other airplanes I trained in. I made no conscious effort to deal with the difference as there were many other things to worry about!
This is also why the island on carriers are on the starboard side, in the early days of carrier aviation, when a pilot jammed the throttle to the firewall on landing in case of a missed wire, the plane tended to pull to the port. So the island was built on the starboard side, preventing a pilot from attempting to park his bird in the CO's stateroom.
Now THAT is some interesting knowledge. Always wondered by the island was only on the side side of carriers.
Akagi and Hiryū were the only two carriers ever built with the island on the port side. This was intended to spread out the landing pattern during multi-carrier operations.
So they just kept it the same over time?
Pretty much. As the transition from piston engined plane to all jet took the span of decades, by the time the last piston plane left the service the Nimitz class were already in commission so changing a class so drastically (the island off balances the ship so the layout of her ballast tanks and machinery is such to off set it, so just moving it to the other side wont work) and retraining the muscle memory of all the pilots didn't make sense, so it stayed on the starboard (right side facing the ship from the stern). This was all required knowledge for the Enlisted Surface Warfare Specialist (ESWS, abbreviated as (SW) after an enlisted persons rate/rank in the case of me it was MM1 (SW) McIlhinney.
This is the type of content I get from channels with more than 100x the subscribers of this one
You guys deserve more
I did R/C model airplanes for many years. All of them needed a little prop offset.
More recently I had a 37’ sailboat with a 50hp Diesel engine. The crankshaft angle was between 15 and 17 degrees. Going forward was OK, but, holy cow, was there an incredible prop walk in reverse that moved the stern to the right. Unfortunately our slip needed the prop walk to be exactly the opposite. We wound up wrestling the boat into the slip with brute force.
Never heard of this... Which way was the crank angle off of beam? 15 deg to port or starboard (at the rear looking forward)?
I studied aero engineering because the RC aircraft I designed didn't fly well, prop offset or otherwise. I also have a sail boat. The angle of the prop has very little to do with it. Do you have a foldable prop? most boats I've owned sail like a pig when motored backwards and prop walk only works one way. I'm in a tidal current berth so it might be different if you didn't need speed against currrent to avoid.
Most model aircraft have to have right thrust and down thrust! Normally 2 to 3 degrees
The down thrust is to help on a banked turn to stop the aircraft from rolling in on the turn ! Tried same plane with zero thrust angle and it was a lot more unstable especially on a left turn!
Same I first learned about this in my RC days as well early 90s
@@nastyab8003 Down not sideways. The prop walk comes from the difference in blade pitch between the side coming up and the other side going down.
Fantastic video 10/10. No clickbait, no two minute intro. Clear, easy to understand, and to the point.
I appreciate that!
I just stumbled onto your videos. The explanations on both propeller effects and "coffin corner" are two of the most concise and accurate I've seen. Well done.
Cool, thanks!
Love when informational videos are short and too the point. I, just your average Joe, don’t *need* to know the ins and outs, I just *want* a short and simple answer as to why. You learned why and you became a little smarter. If you wanted to dive deeper, then you can find those long and in-depth videos. It’s almost like a gateway drug.
As an RC model pilot I had a thing for twins. I learned that the total torque effect of two engines was no more than that of one engine. Also, I learned to angle both engines out slightly, the right side engine pointed to the right, the left side to the left. This really helped with one engine out situations, as the toeing out of the live engine countered the tendency of that engine to pull to yaw the other way. Designing my own RC aircraft helped me learn about various airfoils, engine thrust, etc, but the most important lesson was to minimize the gap between wing and aileron, elevator and stabilizer, etc. This greatly improved aileron, rudder, elevator authority. Also placing servos as closely to their control surfaces as possible so that control rods were as short as possible, minimizing flexing of the rods. This made the servo to control surface much firmer. Also to avoid all the slop inherent in bellcranks by using two servos for ailerons, one in each wing panel. My planes would groove like a slot car.
That’s dope that a “hobby” that someone would consider simple actually has a whole aeronautical mountain of information you could climb.
Great video. Short and concise! Much better than other videos where people make them 20 minutes long for no reason
I appreciate that!
For literally decades I have known it was ‘something to do with aerodynamics’ but never really why! Thanks to your short and very easy to comprehend video I now finally understand! Thank you!
Glad to help!
Remember though, if you look straight down at any real single engine airplane you WONT notice the offset becuz of how slight it is.
Its only maybe 3 degrees of angle
Yes its very slight.
Quite noticeable on some. I could see it clearly on my CAP 231.
It's the entire engine offset on it's mounts, not noticeable at all.
Car has toe-in and toe-out, and it's also not noticeable by human eyes.
Fantastic explanation! I've always thought it's just the torque produced by the engine that would have a noticeable effect, but turns out it's more than that. I'd imagine putting contra-rotating propellers would solve the airflow issues by straightening the airflow that passes through the second set, but it's also noisier and more complex I'd reckon, AND still doesn't completely eliminate the torque from the engine. Guess to show just how much a simple engineering solution could affect the aerodynamic balancing of a single propeller plane.
The genius of the P-38 Lightning is that by having two props each rotating a different direction AND two tail fins, both the torque effect and the aerodynamic effects are incredibly well balanced. A superb aircraft.
@@fubar12345 And if one engine failed, especially at landing and takeoff, the combined drag of the failed engines prop and the torque from the other would cause a lot of crashes... It had a lot of flaws, compressability, poor heating, engines tended to throw conrods etc...
@@MrZnarffy And if one engine fails in a one-engined aircraft, is that somehow better?
@@fubar12345 You have raised a very good point. Contra rotating props have continued into to modern era. Aircraft such as the Piper Navaho C/R and the Piper Seneca ( Which is still being built) have this feature. The Seneca, especially the later models, are well regarded for their benign engine out handling.
@@zogzog1063 Yes, actually. If the engines are equally reliable and the twin-engined aircraft tends to crash when one engine quits, the single engined aircraft is actually safer, because the likelihood of a crash is lower. Say, for example, that the engine dies on average every 1,000 flights. Statistically, an aircraft equipped with a single engine will experience an engine failure every 1,000 flights, but an aircraft with two of those engines will experience an engine failure every 500 flights. The twin-engined aircraft is only safer if it can safely handle an engine failure.
Easily the best explanation of left turning tendencies I’ve ever seen
Love all your videos! As an aspiring instructor your videos have helped with visualising all these concepts and how to better describe them. Keep them coming!
I'm interested to see your take on explaining thrust.
That’s knowledge I didn’t know I needed. Taking that to the grave with me!!! Now I’m a subscriber.
This is Real Life Engineer,
And I approve this message…
🤣🤣🤣
Excellent video!
I haven’t gone into amateur aviation yet. But I was totally fascinated by this video and its explanations.
Many thanks!
Most simple and easy to follow explanation I have ever seen
Glad you think so!
Great vid.
Some light aircraft have the offset achieved by simply having slightly larger engine vibration damper mounts on 1 side to make the offset just as little as 5 degrees.
All control surfaces create drag, the more they are moved, therefore it is most desirable to use then as little as possible for trim.
- Yeah well, I also "yaw" when I get sleepy.
- Anyway, I've found out that if you replace the plane's control wheel with a leather horse bridle & pull toward right it compensates for the plane's tendency to pull to the left.
- Love the background music!
Pilatus PC-21 uses this , among other high-power-to-weight aircraft. Great explanation!
I had some pain in my left foot this morning but after watching this video the effect was offset a little and I'm more balanced...
for the last explanation: i think it's more about the dihedral (slight V shaped) wings in front of the center of mass. if you the plane is rotated the wings starts to slightly become L shaped. and since one wing has more surface area towards the ground, when the plane goes down that wing drags more than the other means it will produce rotation and a negative feedback loop. but since the plane has mass that makes it sway towards the "flat" side of the wing. though the wing isn't perfectly at the center of mass so it will produce yaw torque, the engine is tilted slightly inducing torque to counteract that.
Agree. The explanation presented in the video was not accurate.
dihedral or anhedral don't need to be mentioned, the principal of torque still applies. The relation to the ground only plays into the gravity factor of the aerodynamic equation. Once you put a plane into a bank the aerodynamics change completely so control input is required to correct.
@@gvc76 The final part of the video talks about engine torque and was accurate.
I am around planes often enough. However I have never noticed that before. I will have to start looking when I am around airplanes at work. Thank you for posting.
Great explanation! I think another way to counter this side effect is to offset the propeller axis from the airframe axis, but keeping them paralleled.
Yes, good point! I remember seeing a blurb or something somewhere about a WW2 plane with the question, "Why is the propeller on this plane offset to the right?" This would obviously pull the plane to the left.
I'm not knowledgeable in aviation, but aren't there also planes with two propellers counter-rotating relative to each other?
Awsome! Explanations for most things are simple and to the point when presented by a professional.
I appreciate that!
These videos are amazing! Keep them coming. In this video - did you forget to mention gyroscopic procession as the 4th left turning tendency? I assume it was omitted because the slightly offset engine doesn't counter that force but it is still good to know that that exists.
Thank you Colin and a great question. My understanding is that gyroscopic precession mainly affects tailwheel type aeroplanes during take off. But you're right, it is an effect worth mentioning so we'll create a video dedicated to it. It is a fairly complex topic to explain.
Amazing? This video is false information. They don't offset the propellers.
@@Normal1855 "They" certainly do! I built my kit plane and fly in it with friends frequently i.e. it's not a rc model and I'm a retired commercial and ex military pilot. Many light aircraft of different types have the engine/propeller offset by a degree or two.
@@flightclubonline gyroscopic precession affects every propeller-driven aircraft because, as you maneuver, you force the spinning mass on the front of the plane to change planes. The gyroscopic effect does not change because of the location of the landing gear. Taildraggers exhibit the force more obviously due to the need to raise the tail wheel during the takeoff roll, changing the plane of the spinning mass during the roll itself. Tricycle gear planes are not affected until rotation. Once pitch is changed, it will manifest itself as a force 90° in the direction of rotation. Thus, on a clockwise-turning propeller, when adding upward pitch, gyroscopic precession would induce a yawing moment to the right. Try this with a child's gyroscope initially spinning perpendicular to the ground. Try to angle it upwards. The force it will exert on you will be to the right if it's spinning clockwise, to the left if counterclockwise. Every propeller-driven aircraft is affected by this force. Counter-rotating propellers balance this out, whether they are on the same or separate shafts. It is actually very surprising that you do not have an adequate personal visualization of this as you attempt to explain the forces involved in flight to others.
Excellent lesson.
Thanks! 😃
I knew there was a reason I always gravitated towards twin engine planes. But I'm sure they have their issues as well. Thank you for the easy to digest and direct video. Subscribed.
Thanks for watching!
WHY IS THIS SO GOOD
legit thought there was gonna be some faults and misunderstandings, but this is simple yet so explanatory
Finally youtube did recommend a good quality video for once
Oh wow, that's great to hear. Thanks so much for letting me know.
So simple when it's explained well.
Will use this in my PLTW AE class. Such a great summary. Thank you!
Glad you found it helpful!
I've the first RC plan and found the motor mount was not straight. My 3-D printed RC plane came with the motor mount model which is not straight as well. These thing lead me to this VDO. Thank you so much!.
Thank you for sharing this information.
Didn't know that. I would get pissed and put a shim or grind it down to make it straight. Then go to the review section and give them a bad review for poor quality control.
Cool , been an A&P for 26 years. Started off on Boeing 727 and other commercial airlines . Work on helicopters now for 16 years there's concepts like this also . Never thought about the angle of attack on a prop plane . Knew about the Tourq effect especially on dual engine planes . Great Video.
Excellent explanation. I'm sure in the early days they just tried what worked and engineered the why later
A lifetime of interest in aircraft and i had never heard of this. Amazing! Thanks.
My pleasure!
That's a beautiful example of how most mathematical models are embedded in a multitude of assumptions. I for myself guessed that it was the off-center weight of a solo pilot in a side by side seating cockpit that would require this tweak of the propeller angle. I was completely wrong, haha
At least that's the reason why especially small cars have a difference in the left and right springs of their suspension.
Well, you are somewhat right in your assumption. If the pilot move out on the wing (adding extra weight on only one wing) it would be heavier and this move faster thru the air than the other wing and make the plane go to the opposite direction. Also - the glide angle (lift-drag ratio) of a plane is always the same no matter what the pilot weight - it only travels the glide-distance faster. Gliderpilots often use waterballast to benefit from this.
@@HeliZero Interesting, I thought a lighter plane could glide a longer distance.
I guess I’ve always noticed it but always thought it was just an optical illusion. I guess you learn something every day. Thank you.
Hello I'm doing my undergraduate course in aerospace engineering. I love all of your videos and your way of explaining. Can you suggest me some similar resources from where I can get help for my academics?
Theodore von Karman wrote several books, Aerodynamics, Fluid Mechanics, etc. If you don't already have those, they're still in print.
Best explanation of P Factor... Simple but concise.
Glad you think so!
Not a pilot, just curious: at 1:30, what is the AoA relative to? The arc size in the diagram seems arbitrary. I would have assumed the arc would start perpendicular to the flight path; the propellor AoA difference would still be noticeable if so.
Blade AoA is the angle the chord line of the blade makes with the relative wind. Relative wind is determined by both the blade’s forward velocity and well as its velocity due to rotation. Sum those two vectors and you get a line for the relative wind which can be used to measure the blade AoA. This is definitely a case of a picture being worth a thousand words.
Aoa is the angle between mean aerodynamic chord and local airflow
@@Hornet135 And further complicating the matter is the fact that the descending blade has different forward velocity than the ascending blade, since the propeller's plane of rotation is not at right angles to the flight path. (You can see in the picture that the airplane's nose is tilted upwards.) And this difference depends on the airplane's airspeed, the angle the plane of the propeller makes with the relative wind, as well as the rotation speed. Cool stuff.
OMG... You really do Learn every day! If you wouldn't have told I wouldn't have known this my entire life.. Thank you.. Just a little off topic... do airliners rent the engine and seats of large passenger plane?
Fantastic video , thank you !!!
I never knew about or even noticed the offset, amazing informative video, you just got another subscriber
Welcome!
@@flightclubonline thank you
MOST airplanes are built with an control surface which offsets the yaw tendency caused by P-Factor
I have always wondered why prop planes never spun around like the way a helicopter would with its tail rotor broke,fascinating stuff and thanks for this
2 years of flight school and they didnt mention this at all.
First of all, I didn't even know that aircraft propellers were offset, thanks for the info
Glad I could help!
The P-factor in level flight where the downward blade (right) gets more bite of air than the upward blade is already counteracted by a downward offset thrust angle built into the mounting of the engine. The only time the P-factor is apparent is when pitching up coupled with high power settings
Does this downward thrust mean that the tip of the motor shaft should be further down? this is it??
I love the music and voice acting! It’s so beautiful!
I would rather not have known this. Now it's going to bother me 😂
Fascinating! EXCELLENT WORK! THANK YOU!!:)
Many thanks!
Thank you.
Fascinating. And what a brilliantly simple explanation, for non engineers like me.
Thank you very much for your kind feedback.
Nice but it’s all wrong.
Spiraling slipstream is a myth that has been around since the publishing of ‘Stick and Rudder.’ There is no mathematics or pictures that prove it exists.
Torque CANNOT be offset by turning the torque axis in a different direction. Torque causes roll which is offset by the wings and ailerons, once trimmed out it doesn’t cause the plane to turn left.
The explanation of P-factor is wrong.
Aviation educators throughout time have confused the Source of the P-Factor with the actual Result of P-Factor.
The Source of P Factor is the asymmetric thrust across the face of the propeller. That is, in a climb or high AOA, there is more thrust on the downward moving propeller blade, than there is on the upward moving propeller blade. As currently taught, it is this additional right-sided thrust, reacting through the propeller, that pulls the plane to the left.
But that same thrust does not act through the same propeller this way. Due to Gyroscopic Precession,) (GP) the applied force at the right propeller results in a reaction 90 degrees to the point of application. So, if the force, applied to the propeller at the 3 o’clock position, then GP will result in a nose up force at the 6 o’clock position. Not a left yaw but nose up!
The Result of P-factor is increased airflow down the right side of the aircraft. This higher velocity airflow just didn’t disappear-we’ve just forgotten that it exists, or even discussed it, for decades!
We need to start understanding that P-factor is the ASYMMETRIC AIRFLOW DOWN BOTH SIDES OF THE FUSELAGE due to the increased thrust caused by the higher angle of attack of the downward moving blade. It’s this higher velocity air, moving down the right side of the aircraft, causes a higher AOA on the entire right side of the aircraft AND the fin and thus a yaw to the left. The slipstream is not pushing the fin over. The fuselage and fin together generate a yawing moment due to its own effective the angle of attack.
Right thrust simply aims this higher velocity air at the far side of the fin and reduces the left yawing tendency.
Thank you, you’ve made some good points. Here are my thoughts about a few:
Spiralling slipstream in well documented in just about every aerodynamics book that I’ve come across. I wouldn’t discard this theory just because there isn’t a picture of it somewhere.
I’m not sure what you mean by “torque axis”. What this clip tries to explain is that shifting the axis of rotation to the right helps alleviate the symptoms of the torque effect. It does this by the means of a secondary effect of a yaw, which is a roll.
Gyroscopic Precession effect is only present as the spin axis changes direction. I’d imagine that if the aircraft was continuously yawing to the left, the gyroscopic precession effect would most certainly have an impact. But that’s not the case, such as in slow flight configuration when the effects mentioned in the video are most significant.
Finally, please don’t start off with “nice but it’s all wrong”. It’s a little condescending and unnecessary.
@@flightclubonline there are all sorts of aerodynamics studied about planes and one I don’t recognise is spiral flow around the fuselage.I know Form drag ( parasitic) which is linear flow along the the body . This is covered in many ways in many descriptions and experiments . People thought the moon was cheese till it was proved it was Rock . Id like to see some flow patterns to your theory before I say it’s any part of the truth . As the guy says the use of ailerons covers torque roll , yeah in slower speed it can have its greatest effect that you can easily see . Watch single prop planes landing on an aircraft carrier, they coming in short and novice pilot slams the gas on full .
@@flightclubonline On the contrary, Spiraling slipstream may be mentioned in books, but it is the ONLY performance affecting factor in all of stability and control that does not have a single equation defining it or how to compute and allow for it. I've studied this for 30 years. 23 books on aerodynamics and stability and control in the FAA library in OKC, not a SINGLE ONE quantified it. There isn't a single picture of the spiral on a tufted fuselage. It was Wolfgang Langewiesche’s best guess at explaining what he was experiencing. And everyone has just accepted it ever since.
Torque is torque. It ONLY acts around the thrust line of the aircraft. It only causes roll. Offsetting the thrust line does nothing to mitigate the forces or effects of the roll.
May be condescending but it got your attention.
@@tomsolinski4151 When riveted aluminum airplanes with some age fly through rain, the water and oxides leave streaks on the outer skin. The streaks generally will originate at rivets, follow the boundary layer airflow for
Oops. Completion of the above reply: The rivet streaks map the slipstream. I saw thousands of such aircraft over a 50 year career. No evidence of spiral slipstream on any of them.
Absolutely had no idea.
I always wondered how they delt with the rotation mentioned at the end, but I never even
thought about the first part.
This old pilot was telling me about an inexperienced female pilot that was ferrying fighter planes during WWII. While near the ground she needed to go around, applied full power causing the plane to invert, smacking the ground and killing her.
I always heard that was a problem with the F4U Corsair because the huge propeller put so much torque on the airframe at low speed. They couldn't use full throttle on takeoff, as was common with other planes, because at low speed this would cause the plane to flip over on its back and plow into the ground. A lot of pilots transitioning to the Corsair from other planes were killed or injured this way.
That's torque roll that was common in gear down flaps down situations with powerful prop aircraft when the aircraft could get ahead of the pilot and too much power was applied to reassert control. Inexperienced pilots tended to be the victims as you point out.
I love videos that teach me about problems I never knew existed
I'd never thought of these factors nor did I know some single engine aircrafts' propeller axis is offset. Nice to learn something new every day. Of course the asymmetrical thrust is speed dependent, but airplanes spend most of the time at constant cruise speeds.
Super clear explanation. Thanks for marking this!
You're very welcome!
I did not notice this and it seems obvious now. Thanks for the video on how engineering can perfect performance
Super amazing and simple presentation. I love it!
Thank you! Cheers!
Very well made and illustrated!! Great! Thank you!
I could fall in love with that voice!
Finally a COMPLETE explanation! One tiny thing: drawing and text of Newtonian reaction do not match.
Very interesting. I had no idea this existed but I found this video to be very interesting. Physics man.
Glad you enjoyed it!
So the effect is offset a little and plane becomes more balanced? :) great video, didn't see this :) would be more carefully watching planes from now on :)
A perfect explanation of the reason for the need to trim the airplane
So interesting!
Trust the lady to bring this to our attention!
terima kasih penjelasannya...nambah pemahaman...sukses selalu channelnya
I’m not sure why this was suggested to me but it was interesting to watch.
Nice. Informative. And the ladies voice is like velvet.
Thank you very much.
beautiful music and beautiful voice.
Thank you very much.
Don't take this the wrong way, this is still an absolutely amazing video, but I just like the way she says that they just kinda moved it to the right a little. Implying that there was no specific measurements to calculate the angle or anything, and that the engineers just said "Let's just scoot this to the right a little... "
There’s a whole semester of physics lessons in these principals.
Bravo! Nice graphics and explanation. You're the best.
Wow, thanks!
That intrusive R @2:04 "Isaacs Newton Third LawR of Motion" is really NEAT
I learned this the hard way with my rc scratch builds 😃 cool video
Great video, this is so educative 👍
Thanks! Very succinct. Now I can go into my CFI exam with a bit more confidence!
Best of luck!
That was great teaching. So easy to comprehend.
Glad to hear that!
Wow! Just wow! As an amateur private pilot I'm not aware of this. I don't recall learning about this in my ground classes.
As a PPL myself I don't recall any full-size (non-model) aircraft actually implementing this.
@@suzukirider9030 It's not the same, but while exploring the blueprints for the WW2 Hawker Hurricane fighter I noticed they'd designed a 1.5 degree offset to port into the rear fin to counteract the clockwise rotation of the prop. Thought it was interesting, as it's not something you'd normally notice.
Wait what?!
It took 42y before I ever heared about this, as a mechanical engineer?! 😮
Mindblown
This is amazing, I have learned something that I would never forget.
#4 "Gyroscopic Precession" (A force applied to a rotating body is manifested 90˚ in the direction of rotation from where it's applied. Since there is an upward force , and the propeller is rotating Clockwise the Force being realized is to the Left of the direction the Plane is traveling.)
Gyroscopic precession only happens when the plane of rotation is itself being rotated, ie, when the plane is pitching or yawing. So nothing happens in steady flight. The lift force on the wing has nothing to do with it.
Love the knowledge and the Sweet Voice 💖
Thank you kindly
that explains alot.
i build a 2-engine bomber in besiege and wondered why it flew so instable.
i fixed it by making one engine spinning the different direction and turned the propellers.
worked pretty well after that - guess the negative effects countered themselfes from then on.
This is so short and beautiful I nearly cried....
I'm an idiot and I was still able to understand that! Great explanation :)
Excellent explanation. Very informative
by pointing the propeller slightly to the right, this effect is offset a little and the airplane becomes more balanced
This is one of the best explanations I've ever seen on anything !!!!!!! A moron like me can even understand it !!!!!!