Translating Tendency in Helicopters

[@arthouston7361]

As an instructor, I learned to "keep it simple." In your drawing, you have two force vector arrows on each side of the tail rotor location, and I think you should use just ONE arrow, showing the direction of force the tail rotor is producing. So, when the tail boom is trying to move clockwise as a result of reaction to the force being applied to the main rotor disc, you could show the force direction of the tail rotor countering the rotor disc reaction, preventing the tail boom from moving in that direction. In other words, "begin with the end in mind." the point of thrust is the job it is doing. In the case of the main rotor, the force is against the thrust bearing (and then the engine and transmission mounted to the airframe) to lift the aircraft. In the case of a plane, it is to pull the airplane forward on its bearings and engine mounts. The one arrow pointing in the direction of translating tendency might make it a little more clear. HTH.

[@frankjuniorjaspers6462]

I'm learning for my ppl and i already learned so much from you and your video's. Thanks for all the lessons. you explain everything in a simple, understanding and clear way. Thank you for all the effort you make by making these video's. You are the BEST!!!

[@rectorsquid]

It's very interesting to me to see all of the aerodynamics you teach in your videos happening in my small RC helicopter. When I use the tail rotor to yaw in a hover, the translating tendency is very apparent and the helicopter slides sideways if the cyclic is not adjusted appropriately. I already knew about that tendency because it's a fairly obvious expected action. But your lesson on VRS was enlightening because I didn't previously understand why that tiny helicopter would accelerate downward when making a quick descent without forward speed. I have a private pilot license but I don't think I'll be lucky enough to put these lessons to use in a full-size helicopter anytime soon. At least I can be an armchair helicopter pilot flying the RC heli around now and then.

[@amartin7607]

Great videos, I have a slightly different understanding of why the helicopter sits left skid low however. Interested to hear your thoughts on this. The disc tilt to overcome translating tendency will not necessarily cause the whole fuselage to roll as it should hang vertically under the disc. The roll is caused by the turning moment in the vertical plane, due to the tail rotor and main rotor being mounted at different heights. Helicopters with the tail rotor mounted high, so at the same level as the main rotor (eg Apache / Huey), shouldn't encounter much roll in the hover. Those with the tail rotor mounted low (eg Jet Ranger, Squirrel) will experience it more.

[@elelyon555]

Thank you for explaining this, so much more helpful than the books!! 🙏🏼👍🏼😃

[@Munky332]

I have a couple questions about this. I'm a fixed wing guy (Flight Engineer), but I do fly helo's virtually in DCS, and am considering going down the Helo PPL rabbit hole. Now, that is a simulation/game and obviously some liberties are taken as it can't model everything. One thing i've experienced is in the sim, the slip ball (the only real reference to slip, since "seat of the pants" doesn't exist... yet) -- seems to be slightly inaccurate, but I don't have any rotor experience so I'm trying to equate what is going on. UH-1H In forward flight, straight and level, 80kts cruising forward, 0 wind; Aircraft is in a slight crab left (aircraft drifting right from aimpoint), slight amount of left pedal, ball is center. IF I correct for the crab, by decreasing left pedal and even requiring a tad bit of RIGHT pedal, no more crab, but now the ball is showing a sideslip (ball slightly left)? Is this the effect of Translating Tendency? or is it something else? What would be the inputs to correct for this? I suppose one answer would be to just fly it in a crab, but I'm curious about the effects of the flight model.

[@Bendigo1]

You have fly with slight roll to keep it from crabbing. You can not really fly straight and level in the Huey. If you try the rotor and tail rotor will push you sideways. DCS is probably one of if not the best at modeling realistic aerodynamics and flight systems. So it is pretty much spot on with real life. As long as you run it on a computer that can keep up with all the calculations it has to do.

[@ramjet4025]

I first watched this video 5 years ago, and now an FAA CFI, I'm about to do the Canadian FI and reviewed this for my notes on how I'm going to teach this. While this is a great video, it rushes thru this to I think get it done in less than 7 min, it achieves that goal but a few more pauses and slower pace is what I'll be remembering from this hangar talk on TTT.

[@FNGZombies]

I'm not sure if you already have this planned but could you do a video on weight and balance in the future? Your teaching style is definitely the best that I've seen so far, so maybe you could help some of us understand it a little better. Thank you.

[@davidwallace5738]

Another great video. Thanks, buddy.

[@helicopterlessonsin10minut10]

Thunder Domb. I do actually have that in the list of topics to cover. Stay tuned!

[@panicoenduro]

wish i could have the skills to explain so concisely and clearly, thanks for the videos mate, great work!!

[@charliekeyes6206]

Awesome explanation, you doing an incredible job of explaining to us student Pilots. Thank you for sharing your thoughts and your valuable time with all of us.

[@helicopterlessonsin10minut10]

Charlie Keyes. Thanks for the feedback! I'm glad I can help.

[@Dodderja]

I’m student pilot. thank a lot.

[@Blanderr]

As someone prepping for the SIFT your videos have been very helpful

[@MikeKaz9]

I am a complete visual learner and THIS has been incredible.. Great JOB! Will you be getting into Enroute Flight, Navigation, Airspace? I would love to see those videos

[@helicopterlessonsin10minut10]

MikeKaz9. Thanks! We'll see about those topics. Right now I'm focused on the aerodynamics side and leaning towards introducing some aeromedical factors.

[@FRANKSNAKE71]

Clear concise explanation. Nicely done!

[@gerwille]

Thank you, your videos are very interesting and clearly explaining things ! Big up

[@adolfconradigharas439]

Thank you so much brother, this has helped me a lot. May GOD Bless you.

[@tomoliver9544]

First comment ever and I’ve had KZbin accounts for 6 years, great channel keep these coming helping with my ppl in uk! Clockwise spinning is the future (tell your friends) ;)

[@helicopterlessonsin10minut10]

Tom Oliver. I'm glad you enjoy the channel! I'll stick with my CCW rotor, there's no need relearning how to fly haha.

[@Jusaxi]

Niiice Job!! Can you do a video about loss of tail rotor efficiency? Also in a still air / hover turns? Thanks.

[@helicopterlessonsin10minut10]

Jusaxi. Sure thing! I'll add it to the list.

[@Jusaxi]

That would be great. I'll be keeping an eye out for it. Keep up the good job. Helps us dumb fuc**s out A LOT!!! xD

[@ericrobert5296]

Excellent, thank you!!

[@dirtyislandman]

Hey man, love the videos! Going through my private at the moment on the GI bill, hoping to get my CFII at some point. Please keep dropping new content! Your videos are awesome!

[@Kick1776]

How'd you manage private on GI? I know they told me I had to get private THEN they'd help commercial

[@mariojorgepiresdasilva9956]

Good vídeo 👍🏾🚁

[@matrix5062]

Brilliantly explained… I came across this info while looking for answers to RC Heli take off drifts and why one side lifts greater than the other: In experiments: If I mechanically offset the cyclic from its natural position relative to the stick to achieve vertical balanced hover, rather than through Pilot corrective action on the stick itself which then places the stick to its centred position for lifting and hovering which I find is an advantage. Question: Is this understanding applicable if in inverted flight hover...? Plus, what is the effect of offsetting the cyclic on the forward motion, especially at speed, would further compensation be required to maintain straight flight, or will the equal and opposite forces still be matched? Lastly: What about any effect to the tail gyro control through this mechanically altering the cyclic levelling placing it off-centre to achieving a centred flight stick for basic hover. Would they really do this in a 'real Heli'… As you noted: It was an option?

[@tinamwende2572]

all in all good video thumbs up!

[@martellodaguerra]

Hi Jacob, your videos are amazingly good and acurate so thanks in advance for your help. Just one doubt, during my training i was taught to compensate for the translating tendency on the right (i was flying an american chopper H269) using the antitorque left pedal but you said to use the cyclic wich also causes the rotor to tilt left. Isn’t more eficient and simple the use of the pedal instead of using the cyclic? Just asking, aside from that i love your videos (sorry for my not so well english Lol)

[@anthonymccormick2029]

Could you explain why if the tail rotor gearbox is lower than the main rotor it forces a helicopter to hang left skid low? love the videos btw. Thanks!

[@brettknowles3582]

Thanks Jacob, good video

[@P222RL]

thank you for your video, at 3:22 can you explain why the whole helicopter will drift to the right ? suppose the trail rotor thrust has been compensated by the CWW of the main rotor , thank you

[@LockheedHav]

Thanks for your time, Jacob! Hope you are a flight instructor!

[@imdeg9821]

Great video, slight confusion @ 3:36 though. You accidentally said left instead of saying right. I figured out it was a mistake but had me rethinking everything for a second lol.

[@helicopterlessonsin10minut10]

Ian Degre. Great catch. Sorry for any confusion.

[@SMAforce1]

Could you do a video explaining how the dual rotor system works? I’m really interested in how the foot controls work without a tail rotor.

[@helicopterlessonsin10minut10]

Logan S. I'll definitely add that to list. I've got the next 10-12 videos mapped out right now that I want to upload first. But definitely appreciate the suggestions!

[@SMAforce1]

Helicopter Lessons In 10 Minutes or Less Awesome. I’m really enjoying the videos. Plus, they’re helping me out with my private rating so thank you.

[@fklotaloi]

I fly RC helis I can see this effect as u r talking. Thanks for uploading. I did not know the terminology as it says. Thanks

[@oKevn]

Thank you!

[@Marrjuga]

This channel

[@남성나은식]

I'm curious about the reason why the pitch goes up when flying forward in the hover and the phenomenon of the pitch going down after transfer lift

[@G.Harley.Davidson]

Awesome job explaining fir the non Huey pilots, that don’t get this.👍

[@joshuafrey1886]

could you do a video of autorotation aerodynamics?

[@helicopterlessonsin10minut10]

joshua frey. Sure thing! I'll add it to the lineup.

[@10oner]

So u would need to do left cyclic left pedal?

[@StalkR]

Great videos, thank you! Quick question: at the end you explained that to compensate the rotor disk tilts left, but just to make sure I understood gyroscopic precession correctly, in reality it tilts front so that the effect manifests 90 degrees later on the left, is that right?

[@helicopterlessonsin10minut10]

No but I can see the confusion. Gyroscopic precession deals with an input introduced into a point on a rotating body. If you increase pitch in area of the rotor disk, it’s effects will take place 90 degrees later. But when you’re moving he entire rotor disk itself this does not apply. When you offset or tilt the transmission to the left, you in essence change the center of gravity. The helicopter is suspended below the rotor disk like a pendulum. When you shift the point it’s suspended from a little to the left, it stops the translating tendency. I hope this helps. Great question!

[@StalkR]

Oh I see, it makes sense. I understand better GP now. The pendulum analogy is good too. Thanks for the reply and explanations!

[@Kyrelel]

I think you need to expand a little on why the fuselage dips left-skid low. It

[@waleedaj3450]

Hey jacob nice work just got a quick question on the ah-64 cause i fly ah-64 also isn't the transmission tilted to left thats why the trim ball will be out of tow centered line in the hdu symbology? And i know your a 64 ip can you give me any tips on the control touch

[@helicopterlessonsin10minut10]

Waleed Aj. Unfortunately I can't discuss the specifics of the Apache on this forum.

[@realvanman]

Man, I'll bet the aerodynamics for one of those dual rotor helicopters must be very complicated! (Like a Chinook?) Looks like it would be simple with everything opposite between the two rotors, but I'll bet it's not, as they interfere with each other?

[@rajeshkumar-be5er]

thank u sir

[@nighthunter1601]

Why does the helicopter (counterclockwise) yawing to the Right when u push the stick forward without moving the collective and the pedals and ? vice versa? Brothers i need answer

[@helicopterlessonsin10minut10]

I haven’t seen this yaw you’re talking about in the aircraft I’ve flown. It could be something related to your aircraft rigging.

[@johnchurch2321]

Question: Do tandem and coaxial helicopters experience translating tendency?

[@helicopterlessonsin10minut10]

John Church. I haven't flown either types of helicopters. But my from research on the topic it doesn't appear to be a factor for those airframes due to one rotor canceling the effect of the other. I hope this helps.

[@jiezhang542]

So we got compensated for that tendency...That’s the reason why the helicopter Right Skid lift off first... I mean for the Anti-clockwise system

[@HeliZero]

Question: Leaning or Left Skid Low .. does that apply to both rigid heads and teetering rotor systems ... like on the R22 for example?

[@helicopterlessonsin10minut10]

HeliZero. It still applies. But its not pronounced/noticeable the same across all airframes.

[@ltauzzy4151]

This may be a dumb question but how does this combine with transverse airflow and how it already makes you dip right?

[@helicopterlessonsin10minut10]

Austin Taylor. Great question and many people get these confused. Transverse flow pushes the helicopter right during 10-20 knots while translating Tendency effect is due to a Hover. The biggest place you'll notice these 2 combined is the end of an approach. As the helicopter slows down you start to notice Transverse flow pushing the helicopter to the right. At the same time the pilot is cushioning to land by pulling in more power. This increase in power requires more left pedal to keep runway alignment and also produces translating Tendency. Both of these combine to push the helicopter right and you'll see pilots constantly landing right of the centerline.

[@ltauzzy4151]

Helicopter Lessons In 10 Minutes or Less ah I gotcha that makes sense! Awesome explanation as always! Thank you so much

[@nickpepper4592]

Made it sound easy

[@danthemanpatrick]

is the tail rotor of the ch53 canted over to the left to counteract this translating tendency?

[@helicopterlessonsin10minut10]

I can’t speak specifically for the CH53. But some helicopters with that design say that it does produce a slight amount of lift and helps to adjust the attitude of the helicopter to make it more level.

[@hasibulhasan4365]

But as per gyroscopic precession must is rigged forward not to left. Like bell 206 L4

[@salehaljraid6499]

Does the blades turn against the clockwise or with?

[@helicopterlessonsin10minut10]

Sales aljraid. In this example and in most American designed helicopters they rotate counter clockwise.

[@salehaljraid6499]

Helicopter Lessons In 10 Minutes or Less , great, thank you so much.

[@salehaljraid6499]

Helicopter Lessons In 10 Minutes or Less I get a little confused cos I am training on the Guimble and it’s made in French. So its blades turn with the clockwise.

[@heli_adams]

Wouldn't another form of compensation be to mount the tail rotor in the plane of the m/r disc?

[@helicopterlessonsin10minut10]

Jeffrey Adams. You are correct. Perfect examples are the CH-46 and CH-47 helicopters as well as the coaxial design.

[@MsJhook]

3:38 you said left

[@dwightmoore-brown8303]

Archaic? Is that an “old” comment?