Leadouts(Re:Bellcrank Position)

On one of the posts Leonard mentioned that Matt lost a bolt on the line slider while flying. Must be glad he does not have a long adjustable line slider. On our navy carrier planes we have line sliders that trip so the leadouts can slide back at the leadout guide location. Depending on the bellcrank, when line slider trips, we suddenly have an elevator completely out of trim. Either more up or down depending on bellcrank. I have started using a trap on the rear leadout to stop the change in elevator setting. But, as all the sayings in the posts, "Put bellcrank close to center of gravity, then set leadout location to get plane to hang on leadouts the way you want". Then all the rest is wing tip weight, engine offset, rudder offset and leadout location. DOC

Yes. What happens is that someone draws up a force diagram, does some analysis, and it conflicts with conventional wisdom. The problem comes in with how we view that answer: "Everyone else must be wrong, because the analytical result of training and education proves it."

A less biased response to the analytical result might be, "Wait a minute, the analysis is the correct answer to the problem, but it conflicts with real world experience and common knowledge existing for decades." "Perhaps there is a flaw in the way the analysis is set up."

As we (the group) have correctly done, experiments were conducted next. The majority of those experiments seem to agree with the common knowledge and experience. Now we are in the process of explaining (debating?) it.

Engineers face this almost every day in their careers. Some take the position that the analysis is always right. Others take a different approach, and work with the guys in the field to understand why there's a different position.

** DISCLAIMER - PLEASE READ **
I'm not accusing an individual - it's obviously a "group" thing. I am also not referring to recent diagrams drawn up in these posts, but to historical analyses. Again, these are ONLY hypothetical quotes - intended to convey the psychology, not to accuse any individual! It could apply to psychology in articles all the way back to the 40's. The "analysis must be right" approach could also apply to me at various points in my career.

Doc and Tom,

Agreed.

The analysis CAN be wholly accurate ONLY if we know ALL the factors at play, and can get close to accurate numbers, locations and directions of the forces involved.

If we can't assess these things well enough, we under- or overvalue some factors, and then OUR insufficient analyses and predictions will get bit in the butt and look dead wrong.

IMHO, somewhere between total uselessness and absolute Law of Nature certainty, we can get useful, dependable insights.

This is a hobby, a pastime, for most of us. We're free to explore any aspect of this activity that attracts us -- hobbies are voluntary activities, right? If we HAVE to do it the way some actual or popularly elevated 'Hero Idol' insists, just the pressure to do so takes some of the appeal off things for me. I'd rather work it through a bit to grasp why it works -- if it actually does -- then, if justified, JOIN in agreement to go that way.

So if some of us get nauseous at the sight of an equals sign, and others can't understand simple (insert preferred native language here) without three integration symbols before the first variable, so what. The first guy can blink, look further down the page; the second can generate his own blackboard full of exotic symbols if he needs to. Whatever turns each of us on, eh?

I guess this is why I have been playing with model airplanes for so long. Also they helped me with recovery years ago when I wasn't as smart as I thought I was. I remember Wayne Meriwether flying an actual straw broom, just to show someone it could be done. Wing from an old combat plane, stab and elevator from another. The motor mount was cut out of pine, was not expected to fly that long. Anyway I think he got a new precision aerobatic Nobler kit for his efforts. --DOC Holliday

>Yes. What happens is that someone draws up a force diagram,
>does some analysis, and it conflicts with conventional
>wisdom. The problem comes in with how we view that answer:
>"Everyone else must be wrong, because the analytical result
>of training and education proves it."

A more common "method" is for someone to post an analysis, and then explains how it relates to experience, and how it conflicts with some "conventional wisdom" that has been "common knowledge", but wrong, for 50+years. And then have a few people disagree vehemently, and "prove it" with a list people who might have said a particular thing over the years. Or by simply denying it and saying "it's a matter of opinion" or "why can't you listen to every point of view". The word "believe" gets used a lot, too.

Usually, the "vehement disagree-ers" are guys of very limited experience, or have been doing it at a low level for a very long time. Or upper advanced fliers just about to move up to Expert. I believe that psychology is at work here, as "sticking it to the big guys" is subconciously or conciously making them feel like big shots. Since they don't actually know what they are talking about or they know only one aspect of what they are talking about, but are DEAD CERTAIN they are right, they quickly lose the rational portion of the argument, and then resort to claiming that they are being "beat up" or "ignored" by the real experts. Etiher that, or they start posting indirect "meta-arguments" about the philosophical aspects of arguing about it.

same disclaimer

>>Yes. What happens is that someone draws up a force diagram,
>>does some analysis, and it conflicts with conventional
>>wisdom. The problem comes in with how we view that answer:
>>"Everyone else must be wrong, because the analytical result
>>of training and education proves it."
>
>
> A more common "method" is for someone to post an
>analysis, and then explains how it relates to experience,
>and how it conflicts with some "conventional wisdom" that
>has been "common knowledge", but wrong, for 50+years. And
>then have a few people disagree vehemently, and "prove it"
>with a list people who might have said a particular thing
>over the years. Or by simply denying it and saying "it's a
>matter of opinion" or "why can't you listen to every point
>of view". The word "believe" gets used a lot, too.
>
> Usually, the "vehement disagree-ers" are guys of very
>limited experience, or have been doing it at a low level for
>a very long time. Or upper advanced fliers just about to
>move up to Expert. I believe that psychology is at work
>here, as "sticking it to the big guys" is subconciously or
>conciously making them feel like big shots. Since they don't
>actually know what they are talking about or they know only
>one aspect of what they are talking about, but are DEAD
>CERTAIN they are right, they quickly lose the rational
>portion of the argument, and then resort to claiming that
>they are being "beat up" or "ignored" by the real experts.
>Etiher that, or they start posting indirect "meta-arguments"
>about the philosophical aspects of arguing about it.
>
> same disclaimer
>
> Brett
>

The people you are talking about I wonder just how many airplanes they have built. And were they willing to try something out of the norm? I have.

Inertia is a funny thing and can't be explained with force diagrams and numbers. Because each instance is different. Just as no two like models fly exactly the same. Be it wood density or BC location CG location or even how the paint was applied.

The way it has been explained you could theoretically put the bell crank in the middle of the fuse between the wing and stab. I don't think I would like to try that. All I have been relaying all along is I can fell the difference in the way the model fly's. After building hundreds of planes in my life I should be able to at least by now if it's in trim.

So the real life experiment as I stated in another thread is to build two full size PA planes with the BC in different locals and see if you can feel the difference. Bet you can. Let me know how it goes.

No disrespect just my opinion.

>Inertia is a funny thing and can't be explained with force
>diagrams and numbers.

No offense, but WOW!

>>Inertia is a funny thing and can't be explained with force
>>diagrams and numbers.
>
> No offense, but WOW!
>
> Brett

Well please explain to me why sometimes a straw will go through a 2x4 and other times it won't. Or why sometimes a 40 mph car crash hitting a object is worse than a 60 mph crash hitting the same object? EDIT same car under same conditions because according to the math a APPLE IS A APPLE AND A ORANGE IS A ORANGE.

Just wondering if the numbers could explain. Inquiring minds would like to know. At least mine. Thanks.

PS. Brett I know I got you on this one..

>>>Inertia is a funny thing and can't be explained with force
>>>diagrams and numbers.
>>
>> No offense, but WOW!
>>
>> Brett
>
>Well please explain to me why sometimes a straw will go
>through a 2x4 and other times it won't. Or why sometimes a
>40 mph car crash hitting a object is worse than a 60 mph
>crash hitting the same object?

?????????? Go look up what the word "inertia"means. Then see if your questions (which are quite answerable in terms of straightforward physics and engineering principles) even make sense.

>PS. Brett I know I got you on this one..

No you don't, and I don't grasp why you want to "get me" in the first place. H=I*omega has been known since before the declaration of independence. There's no mystery to any of this.

It's perfectly clear that you don't even know what the word inertia means. I try to be patient with everyone, but you don't have a clue what you are talking about and I feel no obligation to provide you with an education that you should have gotten in the 6th grade if you are simply wasting everybody's time trying to bait me into arguments.

I assume this has now become sport for you, and I won't play.

Well Jim I did some of my own experiments and found that I have been wrong about the bell crank location for some time. After making a few phone calls and talking to some prominent flyers. The told me to set my own experiments and come to my own conclusion. I did Bill N. is right I'm wrong.

If you use the board and bell crank as described in Bills experiments it makes no difference where it's located.

There you have it.

But Brett I stand on the car thing till I get a answer. I have seen this type thing with my own eyes.

>Well Jim I did some of my own experiments and found that I
>have been wrong about the bell crank location for some time.
>After making a few phone calls and talking to some prominent
>flyers. The told me to set my own experiments and come to my
>own conclusion. I did Bill N. is right I'm wrong.
>
>If you use the board and bell crank as described in Bills
>experiments it makes no difference where it's located.
>
>There you have it.
>
>But Brett I stand on the car thing till I get a answer. I
>have seen this type thing with my own eyes.

Were both cars the same color?

>>Well Jim I did some of my own experiments and found that I
>>have been wrong about the bell crank location for some time.
>>After making a few phone calls and talking to some prominent
>>flyers. The told me to set my own experiments and come to my
>>own conclusion. I did Bill N. is right I'm wrong.
>>
>>If you use the board and bell crank as described in Bills
>>experiments it makes no difference where it's located.
>>
>>There you have it.
>>
>>But Brett I stand on the car thing till I get a answer. I
>>have seen this type thing with my own eyes.
>
>Were both cars the same color?
>
>Regards,
> John Jolley
>

Don't know you tell me

>Well Jim I did some of my own experiments and found that I
>have been wrong about the bell crank location for some time.
>After making a few phone calls and talking to some prominent
>flyers. The told me to set my own experiments and come to my
>own conclusion. I did Bill N. is right I'm wrong.
>
>If you use the board and bell crank as described in Bills
>experiments it makes no difference where it's located.
>
>There you have it.
>
>But Brett I stand on the car thing till I get a answer. I
>have seen this type thing with my own eyes.

We're wrong? OK. Howard got me big time. I posted an "eat crow" for Brett on the other thread (Bellcrank #2), but I'm not getting into a discussion about cars.

Maybe I should go back to RC, with no strings attached. My face will be dripping egg for weeks!

There goes Brett beating up on me again!!!

The lost bolt is interesting. This happened to me recently and I had to cut into the wing to retreive the slider, fix the stripped thread (not enough thread area in the aluminum piece) and put in a new bolt. I came up with a solution for my new plane. It's a "captured" slider. I used a piece of 1/4" plywood for the track, milled out a large slot down the middle and a more normal slot that would face the "outside" of the wing. Made an aluminun slider block that keyed to the outside slot and fit into the large milled slot. Bushed the slider with copper tube for the leadouts to pass through and pressed in a small 4-40 steel threaded insert. I then used some 1/32" plywood as a back plate with a slot cut in and glued that to the back of the 1/4" plywood piece so that the aluminum block was completely enclosed in the track unit.

So, even if the screw were to back out, the slider block isn't going anywhere and I'm not likely to strip out the steel insert. Also nice when finish time comes since I won't have to move the slider around as I paint. Don't need to put the bolt in until I'm done

Not a big deal, but it's one of those things that makes life easier for not much extra work.

Randy, could you draw up a small simple sketch of that and scan it to me? I an a bit thick when it comes to getting an image from a discription.

Bigiron [email protected]

Randy, I have been pondering a 'sound design' for this leadout adjuster, as the ones available just aren't quite what I had in mind. If it is not a problem, I too would like you to email me a copy of this 'trick-but-practical' lead-out adjuster. Thanks in advance.
Mike in Atwater
[email protected]

Hi guys,

I'll see if I can come up with something and just post it here. Had I been bright, I would have just taken a picture of the thing when I built it. Sigh... The things that occur to me after the fact are astounding.

If you had been smart, you would not have mentioned it!!! See how much work you got yourself into!!!