Trimming the Tutor II

[Andrew Hathaway]

I've got about 6-7 flights on it now, the ST G51 just keeps getting better.  Even with no set priming pattern it's lighting on the first or second flip.  I've got this recurring problem of the overflow cap coming off every flight.  It's not too far out in the open, so its not getting whipped off by the grass.  But anyway, back to the issues...

I'm flying on 64ft .018's, with the leadouts where they were out of the box, stock tip weight, and stock rudder offset.  It flies with both wings level, but has some funny reactions to wind and square corners.  I'm wondering if anyone else has played with one of these enough to tell me if the tip weight, offset, etc is about right?  I guess I'll probably just have to keep flying it... I haven't had a really calm day with enough time to try anything.  The flights so far have been devoted to getting the engine run stabilized, tank mount secured, and gaining comfort with the plane. 

[frank carlisle]

please describe what it does in corners.

[Andrew Hathaway]

I'll probably have to get more flight time on it in calm air to explain what its doing... basically line tension comes and goes at unexpected times.   I might also be fighting turbulence from trees, and wake turbulence from repeat maneuvers.  It's hard to explain but I guess I was hoping someone would jump in and say that the factory settings are way off...  My first instinct would be to move the leadouts but I've never had them independantly adjustable...

[Steve Helmick]

Turbulence from wind through the trees is scary, but wake turbulence in calm air is worse. Either can cost you an airplane. Wake turbulence is a real good reason to fly 2 laps between maneuvers, even in practise. And back up as you do the series.

With a relatively large and heavy engine, I'd think you might have too much tipweight. In fact, none might be too much. Go easy with it, until you get it really well trimmed.    Steve

[Bill Little]

I've got about 6-7 flights on it now, the ST G51 just keeps getting better.  Even with no set priming pattern it's lighting on the first or second flip.  I've got this recurring problem of the overflow cap coming off every flight.  It's not too far out in the open, so its not getting whipped off by the grass.  But anyway, back to the issues...

I'm flying on 64ft .018's, with the leadouts where they were out of the box, stock tip weight, and stock rudder offset.  It flies with both wings level, but has some funny reactions to wind and square corners.  I'm wondering if anyone else has played with one of these enough to tell me if the tip weight, offset, etc is about right?  I guess I'll probably just have to keep flying it... I haven't had a really calm day with enough time to try anything.  The flights so far have been devoted to getting the engine run stabilized, tank mount secured, and gaining comfort with the plane. 

Hi Andrew,
What are the "funny reactions"??  Just what does the plane do?
And when?
A description, to the best of your abilities (!), will help. 

[Andrew Hathaway]

The best way I can describe what its doing is to say it bounces around at the end of the lines.  Not really hinging, but definitely bobbling around a bit.  Yaw seems to occur in some of the corners also.   

Part of my problem is that I haven't got much time on the plane.  Another is that the flying sites I have available aren't dedicated, so I have my choice of a football field with trees in close proximity, a large open soccer field with no obstructions but occassional gusts, or the third is a nice open field with obstructions to calm the stronger gusts.  Unfortunately I havne't had a chance to get out there, and if I do it'll probably be occupied. 

So how much does that rusty chunk of steel weigh?  At least its not another glob of birdshot impregnated glue.
I left rudder offset and tip weight as it was shipped, and have no offset in the engine. 

[Bill Little]

At first glance, I would say the "bouncing" is probably wind/turbulence problem.  Hinging, as you know, would signify too much tip weight.  Lead out adjustment would probably help the inconsistent tension and yawing.  Each airplane, as we know, is different.  Even though they are all jig built, etc., there are variances from plane to plane.   

How is it overhead?  Have you done the overhead 8s yet?  If it is getting real light there, a tiny bit more speed, moving the lead outs a touch forward, tip weight, are all considerations.  Trimming is an ongoing task it seems.

[Andrew Hathaway]

Overheads seem fine, as do the rounds.  The place it really seems to get squirrelly is in corners, which is making me think its a hinging problem.  I would tend to think that TF would use too much tip weight, rather then not enough.  I would theorize that the heavy lines I'm using would come close to balancing out that excessive weight, but maybe there's even more weight out there then I'm thinking.   Is it like an ounce, or maybe three ounces?  I'd hate to cut into it, cause then I'd have to patch the Monkeykote.

[Andrew Hathaway]

1.4oz doesn't seem too excessive... Our ancient Twister has a 1oz wheel balancing weight in the outboard tip and with the same lines (64ft 018's) it balanced ok when we were flying it with the Tigre 46. 

We just went out and had a nice open flying field, with no strong gusts.  The line tension issues come in at about 45* during more involved maneuvers.   Like the intersection in the horizontal 8's, or the third loop in the cloverleaf.  The vertical 8's and overhead 8's, as well as the hourglass don't seem to have any problems.  I switched to a hard point handle with wider spacing which seemed to help a bunch, before the corners and 90* turns were a bit weak.  The indepently adjustable leadouts kinda bug me.  I usually use a solid block slider, with the leadouts as close as possible to each other, with the Tutor II since their is a solid piece of wing in the middle, it doesn't allow me to move them very far.  Right now the front leadout is all the way back, and the rear is completely forward.  I might look into cutting the solid center out, but I have to determine if that will kill all the strength of the leadout guide.  The phillips head junk screws also are less than ideal.  Nice of TF to make them adjustable, but would have been nice if they looked at how most of us are building out sliders.

[john e. holliday]

Andrew:

     Maybe it is not the airplane.  What handle spacing are you using?  You may be just hammering the corners too hard on the squares.  That is the thing I do too much.  I am flying the Accentor now on .015 X 60 eye-to-eye lines.  Have 3/4 ounce tip weight.  Had to move one clip in on handle from the spacing as I have it on the Byron handle.  Yesterday got three more flights on the combo and it is starting to work.  Oh, I did have to move the leadouts forward about a total of 1/4 inch to stop the yawing.  Anyway keep us posted.  DOC Holliday

[Andrew Hathaway]

Doc, I started with the modified Aldrich Magnum handle.  I slowed the controls down so much at the bellcrank that with the narrower line spacing it wouldn't hardly turn at all.  With the current line spacing (maybe 1/2-3/4" further apart) it turns quicker, but still is very stable. 

I forgot to mention I did slide the front leadout a bit forward, and the problem got worse.  Since it was all the way back before I didn't have room to go back any further cause it was up against the cutout.

In an effort to make the adjustable leadouts more user friendly for my personal preferences I went ahead and cut the center out of the slider.  The slot itself is cut from plywood of some type, but there's a sheer heavy balsa spar at the center behind the center of the tip.  The tip is a solid balsa block relieved above and below the slot on the inboard side of the plywood slot.  So basically I had to remove the 3/4 x 1/8" balsa that was the tip block, then had to relieve the inside of the block to match the rest of the block where TF had removed material.  Then I had to cut remove the plywood between the existing slots.  Finally I had to destroy a fair amount of the sheer spar to allow the front lead out to slide back a bit.  It was a little tedious working through the slot, but now they're just about infinitely adjustable.  I should have a flight report in a few days.

Lousy picture shows the finished product.

[Andrew Hathaway]

This was my second ARF, I started with a Nobler.  My second Nobler is nearly finished and I've got a Flite Streak that should be here Monday.  I like the idea of time saved, and I like the quality of the construction.  It could be better, but its hard to beat.  So far the wings have all been straight, etc.  This ARF was only purchased to have a Tigre 51 platform since my Magnum has been sitting in nitrate for about 11 years without being touched.  It came out of the box and got a complete control system makeover, all new hardware, and nothing else.  Considering its really close to stock it flies great.  Adjustable tip weight would be nice, and as long as they were doing the line slider they could have done it right.  They really reinvented the wheel with their design.  My only other complaint is that the fuselage isn't reinforced very well for the landing gear.  I would expect this one to get a steel roll pin reinforcement in the near future.

[phil c]

If the line tension comes and goes in sharp corners you might want to adjust the rudder offset.  If the plane doesn't stay square on the end of the lines, it will be yawing to varying degrees in the corners, which will change the line tension and also affect the elevator control.

You also might want to try a lighter prop.  A heavy prop will cause more precession in the corners.  The nose swinging back and forth also causes unwanted yaw, line tension changes, and affects the elevator movement.

You also might have too much flap area/travel.  It can cause the plane to sort of stagger in hard corners.  A good test is to try and fly a smooth, not so sharp corner.  If the plane handles that, try tightening it up.  If it starts to stagger you've got problems with the flap movement/size and elevator travel not matching each other.