Texas Parasol

Fred the Red Shirt wrote:
On Aug 14, 5:35 pm, cavelamb himself wrote:

Fred the Red Shirt wrote:

...

Thanks Fred.
That detail is called out on page 48 of the manual.
But I'll note it on this drawing.
Maybe it will make my loyal opposition happy...


Now, to all parties involved in the prior ****ing contest,
"Wasn;t that easy?"

Or, as Andy Bray says he

http://www.youtube.com/watch?v=2YmEiGgwnBI

--

FF


Awright, smartie.

Now go build something!

--

Richard

(remove the X to email)

On Aug 15, 1:48 am, cavelamb himself wrote:
Fred the Red Shirt wrote:



On Aug 14, 5:35 pm, cavelamb himself wrote:

Fred the Red Shirt wrote:

...

Thanks Fred.
That detail is called out on page 48 of the manual.
But I'll note it on this drawing.
Maybe it will make my loyal opposition happy...

Now, to all parties involved in the prior ****ing contest,
"Wasn;t that easy?"

Or, as Andy Bray says he

http://www.youtube.com/watch?v=2YmEiGgwnBI

--

FF

Awright, smartie.

Now go build something!


But I'm not done yet, and so long as I have you in a good mood
I figure I might as well press my luck.

Now, I don't see a vertical dimension locating the holes in the carry-
throughs
for the bolts about which the landing gear legs pivot. But there
isn't a lot
to play with, right?

Here is where it gets interesting. The lower longerons are curved.
That
means if those holes are drilled the same for the front and back
longeron
the axes about which those legs pivot will not be colinear, nor even
parallel. I do not agree that it makes the plane unbuildable. After
all,
there are several photos that show the gear built just like it says
in
the manual.

But that does mean that if the fuselage were infinitely stiff, the
legs
would not pivot and the gear would not flex. I presume the gear does
flex, else landings would be a bit hard on the butt as well as the
plane.

So what DOES flex and how, the lower longeron, the carry-thoughs or
both? Also how, and how much and is that a good idea? (Being light
weight construction, even if those bolts were coaxial there would be
flexure at the attachment point.) Now, if you forgive me for again
raising
a much cussed and discussed issue, that also implies that as the gear
flexes the toe-in, toe-out with change, whether for better or worse is
yet
another interesting question.

So long as the subject is the Texas Parasol, are these matters worth
discussing?

--

FF

Fred the Red Shirt wrote:
On Aug 15, 1:48 am, cavelamb himself wrote:

Fred the Red Shirt wrote:




On Aug 14, 5:35 pm, cavelamb himself wrote:

Fred the Red Shirt wrote:

...

Thanks Fred.
That detail is called out on page 48 of the manual.
But I'll note it on this drawing.
Maybe it will make my loyal opposition happy...

Now, to all parties involved in the prior ****ing contest,
"Wasn;t that easy?"

Or, as Andy Bray says he

http://www.youtube.com/watch?v=2YmEiGgwnBI

--

FF

Awright, smartie.

Now go build something!



But I'm not done yet, and so long as I have you in a good mood
I figure I might as well press my luck.

Now, I don't see a vertical dimension locating the holes in the carry-
throughs
for the bolts about which the landing gear legs pivot. But there
isn't a lot
to play with, right?

Here is where it gets interesting. The lower longerons are curved.
That
means if those holes are drilled the same for the front and back
longeron
the axes about which those legs pivot will not be colinear, nor even
parallel. I do not agree that it makes the plane unbuildable. After
all,
there are several photos that show the gear built just like it says
in
the manual.

But that does mean that if the fuselage were infinitely stiff, the
legs
would not pivot and the gear would not flex. I presume the gear does
flex, else landings would be a bit hard on the butt as well as the
plane.

So what DOES flex and how, the lower longeron, the carry-thoughs or
both? Also how, and how much and is that a good idea? (Being light
weight construction, even if those bolts were coaxial there would be
flexure at the attachment point.) Now, if you forgive me for again
raising
a much cussed and discussed issue, that also implies that as the gear
flexes the toe-in, toe-out with change, whether for better or worse is
yet
another interesting question.

So long as the subject is the Texas Parasol, are these matters worth
discussing?

--

FF


First - you would be surprised how rigid the airframe is.

Sure, all trusses flex. But if you expect this one to flex like a
pop riveted aluminum tube structure you will for sure and certain be
amazed. It doesn't flex at all like you are describing. It flexes
a lot more like a welded 4130 tube structure.

I guess I don't follow why there would have to be flexure in the
structure for the gear to move freely. The gear legs piviot on the
bolts. And, BTW, how far is the gear going to move anyway?

I don't know about any changes in toe-in/toe-out changes with gear
movement. Maybe it does, maybe it doesn't. I've never had a reason
to worry about it. My airplanes all tracked straight.



KISS.

It's real important.


--

Richard

(remove the X to email)

On Aug 17, 10:17 pm, cavelamb himself wrote:

...

First - you would be surprised how rigid the airframe is.

...

I guess I don't follow why there would have to be flexure in the
structure for the gear to move freely. The gear legs piviot on the
bolts. And, BTW, how far is the gear going to move anyway?

In reverse order, it must move, else the bungies would serve
no purpose.

Now, imagine two bars arranged in a Vee. Pin the two ends
to a flat surface and pin the two bars together at the apex, but
do not pin the apex it to the surface. The Vee is rigid. Neither
bar is free to pivot about the end pinned to the table.

Now, move the two ends pinned to the table so that they
overlap and pin both to the table t that point. Now they
pivot because the pins are coaxial.

The TP landing gear is a 3-D version of exactly that
situation.

The effect is clear. The magnitude is what makes it
important or not.


I don't know about any changes in toe-in/toe-out changes with gear
movement. Maybe it does, maybe it doesn't. I've never had a reason
to worry about it. My airplanes all tracked straight.


And I suppose that means the flexure in the airframe is real
small. It would be interesting if someone building a TP were
to look carefully at it while the fuselage is inverted.

KISS

Yes, that is what is very attractive about the TP. It has one
of the shortest build times of the scratch-builts, less than
many kitplanes, and relies on simple technique.

--

FF

On Aug 17, 5:27*pm, Fred the Red Shirt

...Here is where it gets interesting. *The lower longerons
are curved. That means if those holes are drilled the
same for the front and back longeron the axes about
which those legs pivot will not be colinear, nor even
parallel...

Non-Euclidean geometry aside, that seems to me to be a rather sub-
optimal design approach. Nothing that a couple of rod ends or rubber
bushings couldn't fix. But it would probably be lighter and more
effective to just make the gear leg holes colinear, and then build,
adjust, or drill the fuselage to maintain that colinearity.

Bob Kuykendall wrote:
On Aug 17, 5:27 pm, Fred the Red Shirt

...Here is where it gets interesting. The lower longerons
are curved. That means if those holes are drilled the
same for the front and back longeron the axes about
which those legs pivot will not be colinear, nor even
parallel...


Non-Euclidean geometry aside, that seems to me to be a rather sub-
optimal design approach. Nothing that a couple of rod ends or rubber
bushings couldn't fix. But it would probably be lighter and more
effective to just make the gear leg holes colinear, and then build,
adjust, or drill the fuselage to maintain that colinearity.


Which is the way it is done...

--

Richard

(remove the X to email)

On Aug 18, 4:11*pm, cavelamb himself wrote:
Bob Kuykendall wrote:
On Aug 17, 5:27 pm, Fred the Red Shirt

...Here is where it gets interesting. *The lower longerons
are curved. That means if those holes are drilled the
same for the front and back longeron the axes about
which those legs pivot will not be colinear, nor even
parallel...

Non-Euclidean geometry aside, that seems to me to be a rather sub-
optimal design approach. Nothing that a couple of rod ends or rubber
bushings couldn't fix. But it would probably be lighter and more
effective to just make the gear leg holes colinear, and then build,
adjust, or drill the fuselage to maintain that colinearity.

You can't do that without changing the dimensions or the shape of
the fuselage, which means you would not be building the fuselage
per the plans.

For instance, you could make the lower longeron straight between
the two carry-throughs. But the plans call for it to be curved. You
could put a wedge-shaped shim between either the forward or the
read carry-through and the lower longeron, but none is called for
in the plans.

You could use angle with a wider leg on one side so as to be able
to skew the bolt, but the size called out in the plans is not wide
enough.

If built according to the plans, the gear legs do not pivot freely.
Just what bends, and how much when they do flex I do not
know. It would be interesting if someone who has one under
construction were to try to measure that while the fuselage is
conveniently inverted.



Which is the way it is done...


I haven't seen ANY done that way.

In every photo I have seen of the TP undercarriage not one
shows the pivot bolts co-linear. In every case the bolt axes
were parallel to the lower longeron, and therefor skewed
with respect to each other.

--

FF