Plane comes in on take off??

[Gary Anderson]

Hi guys,
Need to pick ya brain a little. I have two Legacies, one an ARF, another scratch build. They both do the same thing, on take off they come in?? I checked wheel roll, plane rolls to outer circle, alignments, everything seems to be okay. Once the plane is airborne, she does great??? Tip weight is 1.5 ounces and that seems to be enough. I always set me engine to be zero and I've checked that several times and that don't seem to be the problem?? The ARF I'm using the RoJett 61 Brett Version, I don't believe not having enough power at take off is the problem?? I'm using 0.21 lines, the same lines I used on the SV 11 and my Stiletto and didn't have this problem?? Yes, I've checked wheel alignment several times?? I guess my question is: Has anyone else had this problem with the Legacy? Don't believe the design is at fault?? I appreciate any input, must have missed something?. I even changed set lead out location and didn't make a difference. Help Help??? Plane flys level??

[john e. holliday]

I am going to ask which side of the circle you are taking off from?    I have learned from experience that on slightly windy days to take off just before what would be the judges position on the circle.   The wind blowing on the rudder and aft fuselage will turn the plane to the outside of the circle.    Make as smooth a take off as possible.  If you insist on taking off on the down wind side, you must step backwards to keep the lines tight.   You say the wheels are tracking straight,  if so you may have to put a little resistance on the outboard wheel.

[John Miller]

You may be experiencing some prop effects. I've recently experienced this when I took out some rudder, after going to a larger engine and prop. In my case, I had to add some rudder back in, or back up fast, on launch.

I also will tend to launch on the upwind side, at competitions. It works as John said. I believe it was none other than Big Art who taught me that one.

[Doug Moon]

Well, it could be the wheel alignment.  You said it is tracking toward the outer circle?  Do you mean it turns right a little?  If so try to get it going straight.  You could be getting a little yaw during the roll.  At release to pulls right and then lines pull it in and then it rolls back out and takes off.

[Gordan Delaney]

Why are you using .021 lines? Is this plane that heavy? If not I`d try using .018 lines. The .o21 lines could be the problem. there quite heavy for that size plane.

Gordy

[Brett Buck]

Hi guys,
Need to pick ya brain a little. I have two Legacies, one an ARF, another scratch build. They both do the same thing, on take off they come in?? I checked wheel roll, plane rolls to outer circle, alignments, everything seems to be okay. Once the plane is airborne, she does great??? Tip weight is 1.5 ounces and that seems to be enough. I always set me engine to be zero and I've checked that several times and that don't seem to be the problem?? The ARF I'm using the RoJett 61 Brett Version, I don't believe not having enough power at take off is the problem?? I'm using 0.21 lines, the same lines I used on the SV 11 and my Stiletto and didn't have this problem?? Yes, I've checked wheel alignment several times?? I guess my question is: Has anyone else had this problem with the Legacy? Don't believe the design is at fault?? I appreciate any input, must have missed something?. I even changed set lead out location and didn't make a difference. Help Help??? Plane flys level??

    Go to .018x64 lines. .021s are grossly excessive.  And check the leadout position - should centered on maybe 1"- 1 1/8" behind the CG.

   Power should not be an issue, since it's essentially at full tilt boogie at release.  My airplane takes off extremely well. You should be around 9800-10100 at launch for about a 5.25 second lap. If you have everything else the way I have it set, and you have to be outside that ground RPM range to get a decent lap time, you need to change the prop until you get about that launch revs and in-flight speed. Anything else, particularly if you have to set it in the 9500 range on the ground, and you are out in the weeds and need to adjust either the pipe length (to support the higher pitch) or the pitch (to correspond with the pipe length).

      Brett

[Gary Anderson]

Hi Brett,
No the rpm's is correct nothing wrong there. I was using the 021 cause I broke my 018 and didn't have another set with me. I'm sure the 021 aren't good for the plane but I used the same set with the SV-11, using the RoJett, and didn't have the plane come in on me. It was interesting to me that both my Legacies did the same thing. The scratch build has a lot weaker set up in her and I figured that could be part of the problem but when Mr RoJett did the same thing it got me scratching my head. Mr. RoJett is at full power when you let her go and ya have to work on keeping her on the ground. I thought maybe the engine was turn in towards the circle, so I checked that and it set at zero the same as I always do. When you roll the plane it turns slightly to the outer circle, this is the way I set up all my planes, cause I fly on grass and it seems to help. I don't set any rudder, I just curve the tail section which has worked out just fine before. I'm going to get a set of 018 made up and see if she still does the same trick. I have to correct this problem cause even when you step back there is still a chance that the lines could catch in the grass and I don't want to lose a plane this way?? The ARF and the scratch build both weight 64 ounces???

[PJ Rowland]

.021 tho lines ? on that model ?

ARE YOU KIDDING ME ?   

I Initially we test flew the Lancaster on .21 tho lines and we are talking about a 120oz 4 engine Beast on a stunter - even then it was like flying with Rope.. Way to much drag, way to much line sag - performance drastically went up when we moved down line thickness.

We dropped down to .018 tho and it was perfect. - Like my fellows I'd suggest .018 tho - 62 ft ;

This could be causing your issues, there is so much line drag that they are pulling the model inward. If I was a betting man I'd put $50 down as this being your major cause.

[Gary Anderson]

Hi guys,
I agree, I'm going to set up the 018 and I bet the problem will go away. Let ya all know after this weekend.
Gary

[Ted Fancher]

Hi guys,
I agree, I'm going to set up the 018 and I bet the problem will go away. Let ya all know after this weekend.
Gary

Gary.  If it's happening just at release there is no line drag.  The airplane should be up to flying speed in just a few seconds, however.  If the inboard yaw happens then it might have something to do with the line size.  I'd check the distance between the CG and the center of the leadouts to be sure the LOs are around the one to 1.25" aft of the CG.  This would be of particular importance if the leadouts are too far forward and your landing gear is trying to make the ship turn right at launch.   Then, when the speed gets fast enough to generate line tension, that tension aligns the CG with the leadout location and the ship yaws abruptly back in.  You could have a quick "out" and followed by a quick "back in" yaw early in the roll.

Another source of inward yaw is having the spanwise location of the CG inboard of the thrustline.  If that is so at launch you've a "moment" between the CG (which will act as a pivot in the yaw axis) and the thrust line which wants to yaw the airplane toward you.  The All American, Sr. is the classic example of this problem and requires a lot of engine offset or "too much" tip weight to allow fear free takeoffs.


Ted

[Gary Anderson]

Gary.  If it's happening just at release there is no line drag.  The airplane should be up to flying speed in just a few seconds, however.  If the inboard yaw happens then it might have something to do with the line size.  I'd check the distance between the CG and the center of the leadouts to be sure the LOs are around the one to 1.25" aft of the CG.  This would be of particular importance if the leadouts are too far forward and your landing gear is trying to make the ship turn right at launch.   Then, when the speed gets fast enough to generate line tension, that tension aligns the CG with the leadout location and the ship yaws abruptly back in.  You could have a quick "out" and followed by a quick "back in" yaw early in the roll.

Another source of inward yaw is having the spanwise location of the CG inboard of the thrustline.  If that is so at launch you've a "moment" between the CG (which will act as a pivot in the yaw axis) and the thrust line which wants to yaw the airplane toward you.  The All American, Sr. is the classic example of this problem and requires a lot of engine offset or "too much" tip weight to allow fear free takeoffs.


Ted

Hi Ted,
I will check the leadouts, cause I believe I have them in front of the C/G but I have to check to be sure?? Thank everyone for your input cause both planes flys very well just can't live with the plane coming in on take off.
Thank You
Gary

[Howard Rush]

If it's happening just at release there is no line drag. 

But lines have mass, which when accelerated, also make a force, and with a significant moment arm (1/3 of line length, by my calculation)

Another source of inward yaw is having the spanwise location of the CG inboard of the thrustline. 

For 65' handle to airplane centerline, I figure that going from .018" lines to .021" lines is equivalent to moving the CG 2" to the left.  What do you get?

[Brett Buck]

But lines have mass, which when accelerated, also make a force, and with a significant moment arm (1/3 of line length, by my calculation)

   Indeed. That's what I presume is happening, the effective lateral CG is far inboard of the thrust line. Just like an All-American. Failing that, adding a bit of offset won't hurt anything very much. I, of all people, actually build some in on purpose, about 2 degrees, because the harm is negligible and it prevents exactly this issue. Add to that the fact that heavy lines may also tend to drag in the grass, and formula for disaster.

     Brett

[Ted Fancher]

But lines have mass, which when accelerated, also make a force, and with a significant moment arm (1/3 of line length, by my calculation)

For 65' handle to airplane centerline, I figure that going from .018" lines to .021" lines is equivalent to moving the CG 2" to the left.  What do you get?

You've got the con, Mr Spock.  I'll refrain from further confusing the masses...um...er...Newtons.

Kirk

[jim ivey]

probably none of the above, most lilkely culprit is a wing warp, "wash in" , check that. 21s are a little heavy but not enough to cause this. I don't know the airplane but I think you have more problems than lines. all that outbourd weight gives me a clue. 1/2 ounce should be more than enough.that extra ounce sounds like you are trying to hold that wing down Check your control sirfaces ,make sure they are all zero zero on nuetral.  jim

[John Stiles]

Are the brakes locked up? I had a plane that was having the same trouble.....had a small bit of dry grass wrapped on the axle. It was the outboard axle causing me to neglect checking that all together. When I decided to put larger wheels on, I found it.

[John Stiles]

Oops, sorry.....I'm working on a project, and did a quick scan of the OP....I see now where you checked wheel roll.

[Doug Moon]

Also, it should be noted if you plane to set the center of the LOs 1.25" aft the CG you will need to be using 0 rudder offeset and or no rudder airfoil.

If you are running an airfoiled rudder or rudder offset you will end up with your LOs further forward.

Just something to note....

[bill bischoff]

Doesn't everybody see the big red flag with leadouts FORWARD of the CG? 

[Brett Buck]

I will check the leadouts, cause I believe I have them in front of the C/G but I have to check to be sure??

  Uh, IN FRONT of the CG?  It needs to be BEHIND the CG as I mentioned earlier.

   Brett

[Ted Fancher]

Doesn't everybody see the big red flag with leadouts FORWARD of the CG? 

Hi Bill,

This is the text of post #9 without which Gary might never have mentioned the location of his leadouts.  It was also the first mention of the importance of having the the CG outboard of the thrustline.

"Gary.  If it's happening just at release there is no line drag.  The airplane should be up to flying speed in just a few seconds, however.  If the inboard yaw happens then it might have something to do with the line size.  I'd check the distance between the CG and the center of the leadouts to be sure the LOs are around [the] one to 1.25" aft of the CG.  This would be of particular importance if the leadouts are too far forward and your landing gear is trying to make the ship turn right at launch.   Then, when the speed gets fast enough to generate line tension, that tension aligns the CG with the leadout location and the ship yaws abruptly back in.  You could have a quick "out" and followed by a quick "back in" yaw early in the roll.

Another source of inward yaw is having the spanwise location of the CG inboard of the thrustline.  If that is so at launch you've a "moment" between the CG (which will act as a pivot in the yaw axis) and the thrust line which wants to yaw the airplane "about that pivot" and, thus, toward the pilot.  The All American, Sr. is the classic example of this problem and requires a lot of engine offset or "too much" tip weight to allow fear free takeoffs."

By the way, while copying this I noted a couple of typos that could stand to be corrected.  The extra and unnecessary "the" is in brackets and colored brown now.  Mr. Rush has already taken me to task for not addressing the inertia of the heavier lines, a sin for which I've duly prostrated myself in his direction.  The bottom line is, I think, that the nudge about the leadout location relative to the CG back in post nine will likely help get the Legacy under control from start to finish.

I expect you just passed over that earlier post if you've come to the discussion a bit tardy.

Ted

[Howard Rush]

First thing I'd do (as many others suggested) would be to switch to .018" lines.

[Ted Fancher]

Also, it should be noted if you plane to set the center of the LOs 1.25" aft the CG you will need to be using 0 rudder offeset and or no rudder airfoil.

If you are running an airfoiled rudder or rudder offset you will end up with your LOs further forward.

Just something to note....

Hi Doug,

You and Brett could have an informative discussion on that subject!
Ted

[Brett Buck]

You and Brett could have an informative discussion on that subject!

  No way, I ain't helping Doug any more, he's good enough the way he is.

    Brett

[Steve Helmick]

I'm thinking that some drag on the outboard wheel will be more effective on takeoff than any tailwheel realigning you could do (knowing that Gary usually flies on grass at the PC). The Legacy has quite a wide track LG, so if the inboard wheel has more friction than the outboard, it could be the start of the problem.

Certainly, the change back to .018" lines will help a lot, but another thing I would consider doing is standing fully upright and keeping the handle high, to lift the inboard wheel first and load the outboard wheel more. But maybe Gary is already doing that?  Steve
 

[John Fitzgerald]

When flying off the somewhat rough grass in most places I fly, I lift the handle high on take-off, step back slightly, and get the model off the ground as soon as it can fly.  Helps to avoid line and wheel snags in the grass.  Also helps to start the take-off 3/4 down wind.  I have had models come in due to snags, and it's not fun ducking as they go overhead and then running upwind to try to recover before they break the lines or crash.  I bet it looks almost comical to bystanders.

[jim ivey]

 wing WARP!!!!!

[Brett Buck]

wing WARP!!!!!

   There is absolutely no information in this post suggesting anything like a wing warp.

    Brett

[john e. holliday]

Not fast enough yet for wing warp yet.    

[Doug Moon]

  No way, I ain't helping Doug any more, he's good enough the way he is.

    Brett

 

Same here bud! 

I am not giving out any tid bits of info that could help BB beat us up any more than he already does.

 

[Doug Moon]

I just thought of something really simple.  I try to always go the simple route first.  I have been following this thread but I cant remember if it has already been said so here goes.

Steve mentioned the model has a wide gear track. I have noticed over the years flying models with wing gear are more senstive to my position relative to the plane at take off than models with fuse mounted gear.  

It is very important to position yourself so that your lines are running as close to 90 degrees to the model as possible at take off.  If you are standing behind the model or the model is pointed out away from you, or both, at release it will instantly yaw inward when it starts to roll to straighten itself out in relation to your position in center of the circle.

I have found you want to be in the exact position, relative to the model, at take off as you would be in flight.  I have learned to look at the model as it is being held waiting for release and adjust my position in the circle to try get as close to 90 as possible.  So far I have found for me this gives the smoothest release to roll transition.

[jim ivey]

warp is obvious to a blind  guy.It doesnt matter what I say some guys will disagree just to be disagreeable to me. I was trying to help the guy. I don't really care if you disagree, ya aint gonna straighten that wing with B.S.!!!! WHEELS are not ever gonna cause an airplane to roll up the lines like that. A warp or misaligned flaps or elevator will.

[Gary Anderson]

Hi guys,
Heres a picture of my scratch build Legacy, maybe tomorrow we'll find out the problem with plane coming in on take off. Wish my luck? The other Legacy is the ARF.

Gary

[EddyR]

I think I know what the problem is. Wing is warped,lines to heavy,inside wheel is locked up.taking off into the wind. You are supposed to run like crazy screaming "it is after me, it is after me" and then look real cool after you get control. O did I mention the wing is warped.
 I am sorry but this thread is funny beyond
 EddyR      and I still think the wing is warped

[john e. holliday]

Wait till you have a plane that had one of the straightest wings possible.   No I did not build it.  It was an ARF Flite Streak.   It had engine off set as well as the rudder.  Wing tip weight was not added as it was already a heavy out board wing.   Was flown on .015 and .012 lines 60 feet center of plane to center of handle.   It flew with the out board wing down on level laps and up while inverted.  Never came in at me at any time from launch to landing and was flown off of grass.   My flying partner at the time cut up a coke can(don't like Pepsi) and made a trim tab.   We got the wings to fly level and I never noticed any difference in the flying.  By the way the plane was jigged up and measured and could not find the warp if there was one.   I know I couldn't see it and neither could my flying partner.

[Gary Anderson]

Hi guys,
There is no wing warp or any other warp, Maybe me? We had a nice day for flying but my illness didn't let me play with my toy. In the air the plane flys level both ways. The reason for 1.5 ounces of tip weight is cause that equals the line weight and has worked on many different planes for me. I checked the leadout location and it seems to be where Ted said it should be. In the air the plane has a nice pull in all positions, setting my engine on zero has always worked for me. On my profiles I have a offset but very little and I also use tip weight with profile, it just works for me. I appreciate all the input and if I get this problem ironed out I believe it will be my next competition ship.
Thank You
Gary

[Dick Pacini]

Gary, is it possible the turning in is a result of engine torque/prop diameter?  The RoJett is a strong engine and very popular, based on what I have read.  It could be just one of those things that is a combination of that particular power choice in that particular airframe.  Are you using the same engine in the other plane? 

[Gary Anderson]

Gary, is it possible the turning in is a result of engine torque/prop diameter?  The RoJett is a strong engine and very popular, based on what I have read.  It could be just one of those things that is a combination of that particular power choice in that particular airframe.  Are you using the same engine in the other plane? 

Hi Dick,
No I'm using a Tigre 51, they seems to have the same results. Both want to come in on take off but I haven't tried the 018 lines, I believe that will help. The RoJett is very strong and will jump in the air, the Tigre wants to roll a bid before she will jump in the air. Once airborne both planes makes a very nice turn to outer side of the circle, no jerking , just a nice return to where they belong. Both planes the wings are level both ways, turns very nice corners and seems to turn equal each way. I believe if I weighted the 021 and figured out the drag, (which that is beyond me), it would be like a light coming on. I guess I could rig up a dragging wheel to fool the plane but I think I will try the 018 and go from there?? I appreciate your input.
Thank You
Gary  (Doc gave me permission to play, so maybe tomorrow??)

[Brian Massey]

Gary  (Doc gave me permission to play, so maybe tomorrow??)

Gary, I hope that means you'll be out tomorrow. I'm planning on being there along with Norm and Chuck, but not until "around" 11am so the chill will wear off, and the ground dry a little.

Hope to see you.

Brian

[jim ivey]

  There is absolutely no information in this post suggesting anything like a wing warp.

    Brett bl aaah ha hahaha 

[Ted Fancher]

Gary,

One more thing I just noticed looking at the picture of your ship.  Both wheels are noticeably "toed" out.  I know you said it track straight ahead when you roll it but I'm wondering if you don't get some "chatter" with the wheels trying to track "away from" the straight line the airplane is rolling on?  If you're flying off of a hard surface your launcher or a flying buddy should be able to monitor the wheels during the takeoff and landing roll.  I'd almost bet you're going to find out that at least the outboard gear is "tracking out and springing back, tracking out and springing back over and over again.  Having the inboard gear toed out a "little" isn't all bad and the outboard should almost always be toed in a bit to get them to roll smoothly as the airplane goes around the circle.

You might want to try what I do when I bend and install a set of gears.  Take the wheels off the axles and lay a yard stick/straightedge from axle to axle.  Tweak the gear until both axles are parallel to your straightedge.  Try takeoffs and see if there's any difference.  Don't be afraid to teak a little "toe in" on the outboard gear as you refine the wheel "trim".

Don't know if this is any part of your problem but the wheels don't "look" right in that picture.

Ted

[John Cralley]

Gary, Ted is right, Your plane sure looks duck-footed toed to me. 

[Gary Anderson]

Hi Ted,
You're correct both wheels are toed out, I thought it would be okay, cause the plane rolled straight. You're probably correct, I'll straighten out the wheels before I fly her.

Thank You, I appreciate your input.
Gary

[John Stiles]

Gary, Ted is right, Your plane sure looks duck-footed toed to me. 

Not to mention the fuse is shaped like a banana!

[John Stiles]

Then again....maybe it's time for another chemo shot.

[john e. holliday]

Just went and looked at the pic again.  I thin Teddy Boy has hit the nail on the head.   From day one was always taught to set wheels parallel to each other or a slight toe in.   The toe in came in handy when I was playing with the twiddly stick airplanes.  How many know that the front wheels on a car have a slight toe in if not parallel with each other??  Now back planes.

[Ted Fancher]

Gary,

One other thing just jumped out at me while looking at that picture.  Now this one could just be the camera angle, but...

I get the impression the engine is actually offset slightly into the circle.  Again the prop is at an angle and the camera can distort things but I'd at least do the following to insure that Ted's blind as a bat and he's the one that's crooked.  Set the prop horizontal and measure carefully from each prop tip straight back to the flap hingeline (not to the leading edge because the different taper on an asymmetrical wing would tell you "stories" rather than facts.  To be super accurate measure one side and then turn the prop 180 degrees and measure the other side just to make sure the there isn't any fore and aft angular disparity in the two blades.

I'm probably just seeing things but it's important that the two measurements be at least equal (no offset).  If the distance on the outboard side is greater than on the inboard it could cause the sort of problem you're experiencing.

Have a Merry!

Ted

[Gary Anderson]

Gary,

One other thing just jumped out at me while looking at that picture.  Now this one could just be the camera angle, but...

I get the impression the engine is actually offset slightly into the circle.  Again the prop is at an angle and the camera can distort things but I'd at least do the following to insure that Ted's blind as a bat and he's the one that's crooked.  Set the prop horizontal and measure carefully from each prop tip straight back to the flap hingeline (not to the leading edge because the different taper on an asymmetrical wing would tell you "stories" rather than facts.  To be super accurate measure one side and then turn the prop 180 degrees and measure the other side just to make sure the there isn't any fore and aft angular disparity in the two blades.

I'm probably just seeing things but it's important that the two measurements be at least equal (no offset).  If the distance on the outboard side is greater than on the inboard it could cause the sort of problem you're experiencing.

Have a Merry!

Ted

Hi Ted,
Yes I have done that several times and the props is set at zero. Yes I measure from the trailing edge, also checked to sure the trailing edge was straight. My illness hasn't let me make a trip to the field to try the 018 size lines. I don't have any engine offset and don't like to but maybe that would help. Just seems like once you install engine offset the plane seems to pull harder and I like flying the bigger planes and have the soft touch?? I appreciate your input.
Thank You
Gary

[dale gleason]

Over at Don and Flora Hutchinsons' home, DMAA Christmas Party a few years back, looking at one of Al's planes under construction, I commented he'd need to straighten out his landing gear, the outboard wheel was toed in noticeably.

"That's way I build 'em".

"But, Al, it will roll in at you on takeoff....".

"Not if I have the plane pointed out a little...."
 

Mental note to self.....Wheels in, nose out.

Merry Christmas Everybody!!!    dale g

[Gary Anderson]

Hi Ted, Brett, Howard and the rest of the group.
Got a chance to make up a set of 018 lines and took baby for a spin. I was happy as a lark cause no more problem. The plane made a very nice take off without a problem. As Ted has said do one thing at a time, well I checked all the trim issues, engine set at zero, rudder with nice curve, hinge lines straight with one another. I didn't correct the wheel alingment, I rolled her down the driveway and she turned slightly to the out side of the circle. I need to make a set of wheel pants and straighten the wheels, cause it will look better.

When my partner let her go she just made a real nice take off, as if she knew what she was doing, then she remembered who was behind the handle. She seems to turn a very nice corner and has pride in the air. The G Super Tigre 51 is doing a great job of flying her, five ounces is enough fuel to do the pattern. (I have a twelve ounce tank in her, just for fun???) I'm using the APC 12.25x3.75 prop and it seems to be okay. I believe shes going to give me a lot of fun.
Thanks for your help guys
Gary