FLYMIKE

My Yac pulls to the right often in harrier and when rolling low I can feel the plane reacting to to right thrust it has.....Is it neccessary to have it....and why?

FLYMIKE

Its like the RF G3.5 Yac has no right thrust and i can fly the heck out of that...If you put 2 on the thrust...it flies simular to my extreme flight yac 74".......I can feel the pull.....

FLYMIKE

Ive herd alot of the stories about why the thrust helps..espesially in virtical uplines....but to all the 3D guys....do you take your R thrust out ?

piroflip2

pattern flying is more my thing although I do a little 3Ding.
From what I have read elsewhere on this forum, right thrust is a big help except in the inverted harrier where it can be a disadvantage.
I have right thrust on all my models and indeed I change the amount until I am happy with it.

bubbagates

My Feedback: (32)

FLYMIKE,

A properly setup plane will certainly make 3D easier and that includes thrust angles.

To check side thrust, go to at least 80% power and pull a vertical line, do not correct for anything, just let the plane slow down and watch what it does. If it's pulling to the left you need right thrust, if it's pulling to the right you need left thrust. You also want to do this into the wind, not in a crosswind and you want to make absolutely sure your wings are level before you pull vertical and you have no rudder trim in.

For up/down thrust come into the wind flying perfectly level at least 1/2 throttle. Chop the power and see what the nose does. What you want is the nose to stay where it is until the plane starts to slow. Once the plane starts to slow it will gradually lower the nose on it's own. If the plane suddenly drops the nose you have too much up thrust, if the nose suddenly raises you have too much down thrust.

Do each of the above several times.

You also want to make sure your CG is where you want it and your lateral balance is correct and the prop you have on is the one you want to use. Each of these can effect each of the above so they must be done first.

Also, while you are at it, check to make sure you elevators are moving at exactly the same speed and exactly the same throw. The easiest way I do this is to take to long and very straight sticks of balsa and glue them to spring type close pins. Now clip each one to each elevator half in the same spot on each half and have them meet just behind the rudder. Now move the elevators slowly and you will quickly see if the elevators are perfectly matched all the way through the complete travel range. Throw meters work well but this method is very quick and easy to see the results and cost little to make

krayzc-RCU

My Feedback: (31)

i always correct all thrust aspects (down, right, left, or up) what ever is needed....

Ernie Misner

I do understand what Flymike is saying though. Lots of ARFs come with a ton of right thrust built in. I've been meaning to take some of that out on my Pulse because I am constantly fighting it when inverted.

Thanks,

Ernie

bubbagates

My Feedback: (32)

Ernie,

I have never heard of a right/left (side) thrust issue effecting inverted flight. It's usually up/down thrust or a CG issue. How do you check for side thrust while inverted? I am genuinely curious about this. I have run through countless trimming charts and have never run across side thrust having an effect on inverted flight.

Ernie Misner

Hey Bill, well one of the main reasons that right thrust is needed is because when flying upright but at a slight nose-high angle of attack (which is often), the right prop blade then has more pitch than the left prop blade, causing the plane to pull to the left.

Now when inverted..... and flying at a slightly nose high angle of attack, it is going to pull to the left like crazy because of the "backwards when inverted" right thrust (when upright) that is built in.

Of course the higher the angle of attack, the greater advantage (or disadvantage if inverted) right thrust will be in keeping tracking straight ahead without corrective rudder input.

Takeoffs do benefit from right thrust also because by nature, they are a nose high, or high angle of attack, type of situation where the right prop blade is seeing more pitch than the left side.

Make any sense yet?

Thanks,

Ernie

bubbagates

My Feedback: (32)

Thanks Ernie, I must be really dense today...DOH, you would think that after the amount of planes I have help trim for IMAC I would have been able to figure that out...Talk about feeling dumb....[sm=72_72.gif]

Ernie Misner

No problem Bill. I hadn't thought that through in some time, just had been taking it for granted for a while I guess, so really hoped I wasn't getting too far off.

What's amazing is that lots of folks don't understand the underlying reasons for right thrust. Many think it is to counteract the torque of the engine, but that would be roll-wise, not yaw-wise.

Another reason for right thrust that I have seen explained is that as the propwash curls towards the tailfeathers, it usually induces some left yaw from pressures on the rudder I guess.

Thanks for not ejecting me from the forum....:-)

Ernie

FLYMIKE

Well guys i have to tell you that when inverted harrier coming straight at me the plane pulls to my right....when upright harrier the plane pulls to the right...so common sence says it has to be the thrust which is factory set.....I can correct it with rudder but it doesnt feel natural....

Ernie Misner

In both cases (pulls to right upright, and pulls to left inverted which is to your right if it is coming towards you) indicated too much built in right thrust. I think some of the manufacturers just build in a ton because they "think it is the thing to do".....?

Thanks,

Ernie

Jake Ruddy

My Feedback: (40)

While I understand your complaint I think it's better you starting learning to deal with the thrust now. The main reason for this is sooner or later you will want to expand into flying precision flying. WHen that happens you are going to need the thrust back and then you will have to retrain your thumbs for 3D.. know what I mean?

On my Cap inverted I had to ride the rudder... but after awhile it just became 2nd nature and I didnt think about it.

FLYMIKE

actually it isnt very much built in to this....ive had planes with more...just thinking this yac doesnt need any....I will find out....BTW all the surfaces are in line and level too....Checked with an incedence meter.....

FLYMIKE

Jake Ruddy

My Feedback: (40)

Well it might be worth it to try it without it and see how you like it (thats all that really matters since you are flying it)

bubbagates

My Feedback: (32)

Sorry guys, my connection went down AGAIN right after I created my last response. Actually I was surprised to see it as I thought it did not make it through

Anyway, right thrust actually does two things, it does counter act some of the P-factor (propwash) by actually moving it forward on the vertical fin and it does help eliminate roll but it also does help eliminate some yaw as well.

I always tell people that want to learn basic aerodynamics and how a plane actually flies is to by a copy of Stick and Rudder from Amazon by Wolfgang Langewiesche. It's a very old book and is for full scale aircraft but it also applies to us as well. It's been around so long that the elevators are called "flippers" in it which back when my dad flew that is what they called them.

Ernie, you are essentially correct though, I invite everyone to talk to a full scale Mustang pilot that actually flies one with one of the huge 4 blade props and ask him what he has to do in level flight if he plants the throttle to the firewall, he'll tell you he has to stomp on the rudder to counteract P-factor and add left aileron to counteract the roll and has to slowly let them out once his speed builds.

I still stand by my original statement of properly trimming a plane certainly takes a lot of load off of you. I think Jake can relate to that. When he started in IMAC, myself and another went to fly with him and we flew his plane. We suggested trim changes and he mentioned he felt and saw diufference in the way the plane handled in all modes, I seem to remember he mentioned he still had to do certain things but a lot less of it and it was way more predictable.

Oh Ernie

I'm not that mean YET...

If we lose power once more I may become mean

Jake Ruddy

My Feedback: (40)

Yep def. makes a difference

outssider

My Feedback: (23)

ok, we've established that for imac/precision we need right thrust !!...but that wasn't the question !!!

I fly one 3d maneuver right into another, no imac or precision at all. the only time i have noticed the right thrust hurting me is in a tight waterfall, the plane pulls hard to the right requiring left rudder throughout the maneuver (and it still pulls right).

I am thinking that maybe the right thrust i use is also helping to goof up other maneuvers but i am not picking up on it because maybe it is slight. how about hovering/torque-roll....is the right thrust needed ? or is it just making the maneuver more difficult ?

bubbagates

My Feedback: (32)

Actually what we are trying to say and should have been more clear, a properly trimmed plane will make all types of flying easier, and that includes 3D. It gets the plane to be more predictable and takes some load off piloting it and knowing what the plane is gonna do and making the pilot work less is always a good thing

In a waterfall right thrust will always do that, so will lateral balance

MikeEast

My Feedback: (3)

YES you need to add thrust if necessary (in most every case) to get the plane to track straight and not pull when you throttle up and down. Flying 3D requires just as much precision control as IMAC or Pattern. You can get away without it sure, but if you want the plane to fly worth a flip then you need to eliminate all the torque and coupling issues and get the plane flying neutral otherwise you will be fighting all sorts of problems.

You need to correct the right thrust issue, you need to find the correct CG so that the plane requires little to no trim to fly straight and level, unless you want to start playing with incidence to counteract the coupling. You need to laterally balance, once you get the CG where you want it you need to mix out the coupling ESPECIALLY if you are flying tail heavy. Tail heavy planes want to fly with the tail down (DOH) so you have to add down trim to get them to fly straight and level. Therefore when you are on knife edge not only does the plane want to pitch to the belly naturally in most cases but it is magnified by the down trim. Thats why its really better to trim a plane for neutral level flight and then just learn to hover the thing that way. Its no harder than with a tail heavy plane once you get it right. If you want the tail heaviness to get more "life" out of the plane, just increase the throws, modify to increase if you must and add more power. I assure you most all planes dont need to be real tail heavy to 3D.
You are almost always going to have roll coupling so if you really want a neutral plane you can mix that out too.

ALL of this will make the plane easier to hover becuase pitch, roll and torque induced yaw all have effect even whlle the plane is not flying because of prop wash and torque that are always present. You get rid of all those bad tendencies and the plane will be a lot easier to deal with.

SO if you want a plane that flys "OK", and you dont mind dealing with it with the sticks then that is fine. A lot of people do it and the better you get, the less you notice the little stuff (except the torque problem).

YES if the plane is pulling then you really do need to add right thrust or a rudder to throttle mix to correct the problem.

If anyone says that this is wrong and real pilots fly without mixes or thrust correction I think I just might stab myself in the head with an icepick.[X(]

FLYMIKE

I thought there was going to be different responses to what was said....My Yac flies very well, but in just about every position the plane is in...I am fighting the R thrust to correct the flight path..Just slightly but enough to be irritating..Thats the only problem with this, the 2 degrees in my plane is 2 to many...same in all my planes...exept my foamy.....
I dont feel the remote, I feel the plane and its almost comical...in a conspiracy way LOL...that everyone thinks that it tracks better like this...for the life of me I dont know why i havnt asked about this before or even tried to center the motors on any of my planes...I just notice that there all at 2 degrees and left it at that....

MikeEast

My Feedback: (3)

Just make sure that the plane did not come with right thrust built in. Many of the newer ARFs already have the thrust built into the firewall so if you add more you are going to create new problems.

I dont worry about right thrust in foamies because they are so easy to fly anyway but everything else should have whatever you need to counteract the torque. I would not pin it down to 2 degrees but that is a good starting place, and in my experience usually good enough.

FLYMIKE

Hey Mike, All my planes have R-Thrust built in to the firewall from the factory....That is my gripe...and there is tork pulling the right wing up because of that too...which gives a what everyone calls coupling....so what i was asking is if anyone else can tell (feel) the same problem...if it is a problem....not sure how my Yac is going to fly without-it yet but from what i can tell it should (from common sense), cure what is bothering me...I hope...we will see