Ringmaster Bellcrank

[Chris Fretz]

I demolished my Ringmaster an have the opportunity to change the bellcrank, it has a 3in but would a 4in be of any help?

[Steve Helmick]

Absolutely, YES! If you take the wingtip off (don't neglect adding adjustable leadouts, if it isn't already fitted), you can very easily open up the holes in the ribs with a 3/8" dowel with a bit of 180 grit wrapped around the last 2" or so. Slow the controls down as much as you can, and increase the spacing at the handle as needed to make it work. Don't forget to report back! Steve

[Motorman]

Completely unnecessary imho plus, it won't fit if you have the spar. A longish control horn works just fine with a 3" bellcrank just use the 1st or 2nd push rod hole counting out from the pivot.

I built from RSM plans and the tether point on the plans is right on the money if your plane is balanced right so, you don't need a lead out adjuster.

MM

[Steve Helmick]

Never overlook the chance to learn something, even if it's what NOT to do. And it's GOTTA be more than 4.5" from the LE chunk to the useless spar on an S-1 Ringmaster. Not that I've built any Ringmasters since my first one, in '62/'63.  Steve

[Tim Wescott]

Never overlook the chance to learn something, even if it's what NOT to do. And it's GOTTA be more than 4.5" from the LE chunk to the useless spar on an S-1 Ringmaster. Not that I've built any Ringmasters since my first one, in '62/'63.  Steve

Actually it's just a hair over 3", so you'd need to do some surgery to get a bigger bellcrank to fit.

The plane is small enough that you should be able to get away with a 3" bellcrank, but the suggestion I saw (after, unfortunately, I sealed up the wing on mine) was to bring the elevator wire out as close to the pivot point as you can without binding -- 5/8" was the number given, and that's inside the inside hole on a Sig 3" bellcrank.

[Steve Helmick]

Then, I'd probably leave the spar out. It's pretty much a waste of balsa anyway.    Steve

[Chris Fretz]

From the LE to the spar on mine is 3.800

[Steve Helmick]

Could you tilt the BC so that the rear would clear the spar? Alternatively, you might cut the spar out to clear the BC and add a doubler to the rear, to regain the "strength" of the (nearly useless) spar. Hard to believe the spar would be centered on the ribs, and only 3.8" aft of the club of a LE!  Steve

[Chris Fretz]

Steve, I just glued the useless spar back together the other day.

[Tim Wescott]

Chris, what Steve is referring to vis-a-vis the spar is the fact that as far as resisting the wings flapping it's really not doing much at all.  The bulk of the stiffness of the wing in bending is going to come from the leading edge, some is going to come from the covering, and the spar is really just going along for the ride.

Maybe we could get Steve to build a Ringmaster without a spar to demonstrate -- he can put a 4" bellcrank into it, and compete in Old Time.

[Chris Fretz]

Chris, what Steve is referring to vis-a-vis the spar is the fact that as far as resisting the wings flapping it's really not doing much at all.  The bulk of the stiffness of the wing in bending is going to come from the leading edge, some is going to come from the covering, and the spar is really just going along for the ride.

Maybe we could get Steve to build a Ringmaster without a spar to demonstrate -- he can put a 4" bellcrank into it, and compete in Old Time.

Sounds great! Have at it Steve... In the meantime I think I am just going to slap the thing back together an beat it up some more The bellcrank does however move way more than 45deg both directions so would you build some stops to keep it from moving so much?

[Tim Wescott]

I only put in stops if the bellcrank tends to stick at one extreme or the other.  Even then, I make sure that the elevator has gone way more than is reasonable before any stops are hit.  You DO NOT want to hit the stops.

Why use a stop if you're never going to hit it?  Because if the bellcrank sticks, then some day you may make it turn that far recovering from a slack line condition -- it'll hit a line with a bang, it'll really stick, and then you'll get a chance to learn how to land a plane with a stuck elevator.

[john e. holliday]

I have the 3 inch bell crank in all my Ringmasters.  Pushrod in the hole closest to the pivot point.  Now as far as the spar, I built one with out the spar,  never again.   Guys must not be gluing it right.  As stated, use a tall control horn.   Don't need more than 25 degrees each way.

[Chris Fretz]

This is what I did to it 2 days befote I hit pavement. Flew one with a big tank right before  it an forgot about it with the Ringmaster.            .

[Avaiojet]

Couldn't watch the entire video, I passed out.

[Chris Fretz]

Couldn't watch the entire video, I passed out.

Did I bore you?

[Jim Carter]

    Oh man!!  Can I identify with that maneuver!!  Guess it's why I'm a life member of a club called the North Brevard "Figure 9er's"!!      Hey, just a quick thought .... wanna' join me with a solid investment in the stock market??  Between your flying and my flying .... I'm buying superglue futures!!   

[Sean McEntee]

Way too much work for not enough benefit. If you have the RSM kit, it should come with the stock 1/8 ply horn as came with the Sterling kit, and a similar horn but a lot longer. Use the longer one. Use 3" bellcrank and 3" line spacing at the handle.

That's all you need to slow down the controls and have a very capable model (as long as the weight is reasonable)

[Avaiojet]

Did I bore you?

Liner,

No you did not bore me. In fact I think you're just getting started.     

You fly well.

Shame that Ring.

Charles

[Chris Fretz]

Elevator views are always fun to watch.

[Dane Martin]

Very fun videos to watch. The wing overs in the first video look really cool from that camera view!

[john e. holliday]

After tightening the seat belts so I could watch the great videos t looks like about 15 degrees of elevator is used on the squares and less on the loops.  This reminds me of the videos the Tulsa Glue Dobbers did a few years ago.   By the way was the wing in the first video still in one piece?   I know my RSM version held up on a pan cake crash on its first flight and is still flying.

[Chris Fretz]

After tightening the seat belts so I could watch the great videos t looks like about 15 degrees of elevator is used on the squares and less on the loops.  This reminds me of the videos the Tulsa Glue Dobbers did a few years ago.   By the way was the wing in the first video still in one piece?   I know my RSM version held up on a pan cake crash on its first flight and is still flying.

Check out the degree of movement in this one! http://stunthanger.com/smf/open-forum/first-experience-with-la46/?topicseen

I couldnt believe it but only the monokote ripped on one side but a couple hair line crack around the fuselage. About 15 minutes of work and it was ready for me to pancake it upside-down on pavement 2 days later.

[Ron Cribbs]

It's kinda already been said, but do yourself a favor and use the innermost hole on that 3" bellcrank. It will save you from having to install a really long horn to compensate. Less is more with a Ringmaster.

[Chris Fretz]

Absolutely, YES! If you take the wingtip off (don't neglect adding adjustable leadouts, if it isn't already fitted), you can very easily open up the holes in the ribs with a 3/8" dowel with a bit of 180 grit wrapped around the last 2" or so. Slow the controls down as much as you can, and increase the spacing at the handle as needed to make it work. Don't forget to report back! Steve

Where do you guys get adjustable leadouts at? Ive never delt with those.

[john e. holliday]

Check Brodaks,  RSM Dist or go do a search on Stuka Stunt.  There was a series on there at one time showing how to do wing tips and the guide.

[Tim Wescott]

Someone needs to post a thread that calls on folks to show off their adjustable leadout guides.

There's basically two ways to achieve this, and each one has its variations.  If you look through the various build threads you'll see pictures of how folks have done theirs.

The first way to do this is to use eyelets stuck in holes in the wing tip, with slots between the holes.  I think most people make these by drilling holes in a block of wood for a friction-fit with the eyelets, and then make a slot that's just barely big enough to clear their lines.  You can get eyelets from Brodaks.  Some people use threaded holes, and drill out the center of 4-40 screws (usually brass, although I've seen nylon mentioned).  The eyelet-in-hole technique makes it easy to put things back where they were, but doesn't allow for fine adjustment.

The second way to do this is to use a rail with a slot in it, and a slider that is held in place by a screw.  Brodak sells leadout guide kits for this, too.  This is a bit harder to make yourself than the eyelets in a block thing, but you can make the whole thing out of plywood and a couple of bits of brass tubing.  As you get good you'll want to make the lines individually adjustable -- I'm advanced enough that I've been told by the top guys to do it, but I'm still clueless as to exactly why I'm supposed to be doing it.

[Chris Fretz]

Someone needs to post a thread that calls on folks to show off their adjustable leadout guides.

There's basically two ways to achieve this, and each one has its variations.  If you look through the various build threads you'll see pictures of how folks have done theirs.

The first way to do this is to use eyelets stuck in holes in the wing tip, with slots between the holes.  I think most people make these by drilling holes in a block of wood for a friction-fit with the eyelets, and then make a slot that's just barely big enough to clear their lines.  You can get eyelets from Brodaks.  Some people use threaded holes, and drill out the center of 4-40 screws (usually brass, although I've seen nylon mentioned).  The eyelet-in-hole technique makes it easy to put things back where they were, but doesn't allow for fine adjustment

The second way to do this is to use a rail with a slot in it, and a slider that is held in place by a screw.  Brodak sells leadout guide kits for this, too.  This is a bit harder to make yourself than the eyelets in a block thing, but you can make the whole thing out of plywood and a couple of bits of brass tubing.  As you get good you'll want to make the lines individually adjustable -- I'm advanced enough that I've been told by the top guys to do it, but I'm still clueless as to exactly why I'm supposed to be doing it.

I'm going to bet you guys use the sliding rail ones. I see Brodaks has 2 to choose from,  both look independent.
Ha ha I'm clueless as to why I'm being told to do it

[Dane Martin]

The position of the lead outs control the yaw of the plane while flying around. It's an amazing trim tool. I'm sure one of the intelligent men or women here can explain lots more on the subject

[Tim Wescott]

I'm going to bet you guys use the sliding rail ones. I see Brodaks has 2 to choose from,  both look independent.
Ha ha I'm clueless as to why I'm being told to do it

I'm pretty sure that, even now, Paul Walker uses the eyelets.  I use the sliding rails.

Like Dane says, the leadouts control yaw.  After you get the CG, tip weight, and flap tweak right, getting the leadout position right is the most important trim tool.  Without the correct leadout position you'll either have a plane that needs to go lightning fast to keep line tension everywhere, or you'll have a plane that handles OK in calm wind but won't keep line tension in the overheads enough to handle strong winds.  Since you can't pick your wind at a contest, you really want to trim your leadout position.

Fortunately, all this trim stuff is collected in more than one place by the master himself, Mr. Paul Walker.  You can either become a PAMPA member and download old copies of Stunt News (you want to do this anyway), or you can go here and read all of Paul's articles on trimming.  Even a beginning stunt guy flying alone can get through his basic trim chart, and benefit tremendously from it.

[Chris Fretz]

I'm pretty sure that, even now, Paul Walker uses the eyelets.  I use the sliding rails.

Like Dane says, the leadouts control yaw.  After you get the CG, tip weight, and flap tweak right, getting the leadout position right is the most important trim tool.  Without the correct leadout position you'll either have a plane that needs to go lightning fast to keep line tension everywhere, or you'll have a plane that handles OK in calm wind but won't keep line tension in the overheads enough to handle strong winds.  Since you can't pick your wind at a contest, you really want to trim your leadout position.

Fortunately, all this trim stuff is collected in more than one place by the master himself, Mr. Paul Walker.  You can either become a PAMPA member and download old copies of Stunt News (you want to do this anyway), or you can go here and read all of Paul's articles on trimming.  Even a beginning stunt guy flying alone can get through his basic trim chart, and benefit tremendously from it.

Is yaw the left an right movement of the airplane?
Do you guys have any airplanes without adjustable leadouts?

[Tim Wescott]

Is yaw the left an right movement of the airplane?
Do you guys have any airplanes without adjustable leadouts?

You need a picture, because people are going to talk about pitch, roll, and yaw all the time.

I don't think that anyone who actually wins stunt contests flies with fixed leadouts any more.  I own some 1/2-A planes without adjustable leadouts, but if I wanted to seriously compete with one of them it would acquire adjustable leadouts first thing.

From Wikipedia:

By Yaw_Axis.svg: Auawisederivative work: Jrvz (talk) - Yaw_Axis.svg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9441238

[Chris Fretz]

You need a picture, because people are going to talk about pitch, roll, and yaw all the time.

I don't think that anyone who actually wins stunt contests flies with fixed leadouts any more.  I own some 1/2-A planes without adjustable leadouts, but if I wanted to seriously compete with one of them it would acquire adjustable leadouts first thing.

From Wikipedia:

By Yaw_Axis.svg: Auawisederivative work: Jrvz (talk) - Yaw_Axis.svg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9441238

So you basically have 3 things controling yaw, engine offset rudder an adjustable leadouts?

[Tim Wescott]

So you basically have 3 things controling yaw, engine offset rudder an adjustable leadouts?

Yes.  And while opinions vary, I suggest that you don't use any rudder offset, use just enough engine offset to make sure that it's not inward (I aim for zero engine offset), and spend quality time with the aircraft getting the leadout position correct.

[Howard Rush]

Is yaw the left an right movement of the airplane?

Yes, although it is more useful to consider sideslip: the direction the airplane is pointed relative to the air blowing on it.  It's like sideways angle of attack.  Stunt folks tend to call that yaw, but yaw is something a little different.

Do you guys have any airplanes without adjustable leadouts?

I looked at pictures from the last world championships.  The only airplanes I saw without leadout adjustment were the Yatsenko airplanes and a plane from Moldova.  Lots of people, including Orestes Hernandez, our US team leader, fly Yatsenko planes. 

Below is a picture of my leadout guide, copied from the aforementioned Paul Walker.  It is two pieces of bass separated by some 1/32" plywood so the 1/32"-diameter leadout wires can slide between holes.  Brass or plastic eyelets go in the holes.  This looks flaky, but Paul has thousands of flights on his airplanes, and he adjusts the leadout position every flight or two.  That convinced me that they work.  When the holes wear out, you can shim them with little pieces of paper towel.  One thing to keep in mind with a leadout guide is that any weight there is doubled: you gotta add that much ballast to the other wingtip to keep the sideways CG in the right place.

[Tim Wescott]

Yes, although it is more useful to consider sideslip: the direction the airplane is pointed relative to the air blowing on it.  It's like sideways angle of attack.  Stunt folks tend to call that yaw, but yaw is something a little different.

Well, yes, fine.  The plane is yawed out (or in) from where it should be, causing sideslip.  Picky.

And (Chris), it's the sideslip that causes the problem, so Howard is not out of line being picky: sideslip makes more line tension when you're flying level, because it causes lift, just as in knife-edge flight.  But most of your line tension comes from centrifugal force*, you're going slower up top than at level, gravity's working against you, and sideslip slows you down, reducing your centrifugal force even further.  Much of what you're adjusting for with lead-out position is to get the plane to fly right above 45 degrees.

* I am NOT getting into the centrifugal/centripetal discussion!

[Motorman]

Do you guys have any airplanes without adjustable leadouts?

You don't need adjustable lead outs on a Ringmaster. I don't have them on mine and it's the best flying Ringmaster I've ever had because I just put them in the right place to begin with.

Once you need that level of trim, you should be flying a Sig Twister or one of the other large profile planes.

MM

[Chris Fretz]

Someone needs to post a thread that calls on folks to show off their adjustable leadout guides.

There's basically two ways to achieve this, and each one has its variations.  If you look through the various build threads you'll see pictures of how folks have done theirs.

The first way to do this is to use eyelets stuck in holes in the wing tip, with slots between the holes.  I think most people make these by drilling holes in a block of wood for a friction-fit with the eyelets, and then make a slot that's just barely big enough to clear their lines.  You can get eyelets from Brodaks.  Some people use threaded holes, and drill out the center of 4-40 screws (usually brass, although I've seen nylon mentioned).  The eyelet-in-hole technique makes it easy to put things back where they were, but doesn't allow for fine adjustment.

The second way to do this is to use a rail with a slot in it, and a slider that is held in place by a screw.  Brodak sells leadout guide kits for this, too.  This is a bit harder to make yourself than the eyelets in a block thing, but you can make the whole thing out of plywood and a couple of bits of brass tubing.  As you get good you'll want to make the lines individually adjustable -- I'm advanced enough that I've been told by the top guys to do it, but I'm still clueless as to exactly why I'm supposed to be doing it.

Would you get individually adjustable or the dual adjust kind for someone like me just starting to experiment with it?

[Chris Fretz]

You don't need adjustable lead outs on a Ringmaster. I don't have them on mine and it's the best flying Ringmaster I've ever had because I just put them in the right place to begin with.

Once you need that level of trim, you should be flying a Sig Twister or one of the other large profile planes.

MM

Ugh ugh just ugh

[Steve Riebe]

I am of the opinion you should learn how to install adjustable leadouts, even if it is only in a Ringmaster.  It's difficult to do after the plane is built.  There are certainly other methods of providing for this but it has worked for me

Try this link: http://stunthanger.com/smf/building-techniques/adj-leadout-wing-tip-mounting-step-by-step/

And this link: http://stunthanger.com/smf/building-techniques/adj-leadout-wing-tip-mounting-step-by-step/

[Tim Wescott]

You don't need adjustable lead outs on a Ringmaster.

I'm very happy to have adjustable leadouts in my Ringmaster.  Now that I've converted it to fly Carrier, I need to put the leadouts all the way back.

[Akihiro Danjo]

This is the left tip of my RM S-1.
Aki

[FLOYD CARTER]

The most popular adjustable leadout guide uses a sliding Nylon block, and the holes for wire are about 1" or 1.5" apart. Now, if you use a 4" bellcrank on a plane with a short span, you will always end up with the leadouts bending at the line guide.  This friction hampers proper flight trimming (read: "hunting")

A 3" bellcrank on a small plane is OK, but leadout spacing at the wingtip should be as wide as you can get away with. If using an adjustable guide, modify it for wide spacing.

F.C.

[Howard Rush]

Well, yes, fine.  The plane is yawed out (or in) from where it should be, causing sideslip.  Picky.

And (Chris), it's the sideslip that causes the problem, so Howard is not out of line being picky: sideslip makes more line tension when you're flying level, because it causes lift, just as in knife-edge flight.

Floyd reminds me that I was overgeneralizing by my sideslip comment.  Besides the static part, leadout position affects the airplane dynamic response in maneuvers.  I've never seen an adequate explanation of this subject-- just some simplistic qualitative stuff.  Follow the Walker trim process.  

... leadout spacing at the wingtip should be as wide as you can get away with.

In my case, that has been about 1/4".

[Chris Fretz]

Ohh no fellas I just tried to bench run the ringmaster motor an the shaft is bent first time flying on pavement an my first bent shaft.

[Motorman]

Send it to me I'll straighten it for you.


MM

[Chris Fretz]

Send it to me I'll straighten it for you.


MM

How do you do that?

Can you rebush a case that has a sloppy crankshaft too?

[Chris Fretz]

Back together! Ready to do it all over again.

[Motorman]

How do you do that?

Can you rebush a case that has a sloppy crankshaft too?

I can do anything with metal. What brand/size engine are we talking about?

MM

[Chris Fretz]

I can do anything with metal. What brand/size engine are we talking about?

MM

Testors series 21 McCoy 29.

I put a different crank in it, I believe it was a 35size. I imagine the counter weights are different from 29-35-40. Id say there is a slight vibration in it now. I think it would be happier with the original crankshaft.