Two vs Four

To All:

If you've got a major back pain but absolutely positively HAVE to be
able to walk you use FOUR canes. This turns you into a quadraped.
Two of your 'legs' just happen to be wood. (Or aluminum, PVC or
whatever) But it doesn't matter what those two new legs are made of.
Your body mass is now supported by FOUR 'legs' rather than two... or
three. The only place where you'll have trouble is in the check-out
line.

Did that come across? Your body's mass is now supported by FOUR limbs
rather than two. Of course, the two canes don't carry as much of a
load as your two real legs but when it comes to BALANCE your two
pseudo-legs are about as good as the real thing.

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So what does this gotta do with aeroplanes?

I thot you'd never ask :-)

The landing gear, as a system, represents a significant portion of the
cost when you are trying to build a bucks-down airplane. Cheapest way
to go is to use a stiff-legged landing gear like they used in the
Piper "Vagabond" or the homebuilt "Fly Baby." In effect, the rubber
TIRE becomes the entire 'landing gear.' Of course, that only works
when the tire is large enough.

Want a cheap tire & wheel? You can get a 10" tire & wheel for a 5/8"
axle for less than $5 (!!) (see the closing NOTES). And along about
here you'll discover there's a bit more to your alighting system than
energy absorption. For example, if your tire is too narrow it's
liable to sink into the soft earth and simply stop rotating. Of
course, the airplane will continue rolling right along... but with the
wheels locked to the earth, the airplane will prescribe a graceful
outside loop, prying the wheels free of the soft earth as the airplane
comes to rest on its back, a position that's more embarrassing than
dangerous. Roll it back up-right, buy yourself a new propeller and
you're pretty much good to go, if you're willing to ignore the risk of
a cracked crankshaft or damaged rudder hinges.

The lesson here is that your landing gear must have a significant
'foot-print.' And that means you want a big, fat tire.. such as those
used on the Vagabond or the Fly Baby. Of course, big fat tires cost
more than little skinny tires. As in a LOT more.

But wait! If we put TWO of those little skinny tires together we'll
end up with a 'foot-print' that's almost as big as that of a big, fat
tire. And the price is still durt cheep.

Okay, let's take a look at what we got. We order FOUR of those Harbor
Freight pneumatic ten inch wheels. They cost less than five bux each,
plus the shipping. We rig a 5/8" cross-shaft and put one of those El
Cheepo wheels on each end. Now we've got a foot-print that's bigger
than the Beanstalk Giant and there's a good chance our cheep landing
gear won't sink in and flip us over on our back.

Of course, it would really be swell if we had a landing gear that DID
address energy absorption. And since we've already started with those
cheap 10" wheels let's stick with them and see what we can come up
with.

First off, let's get rid of attaching two wheels to each landing-gear
upright. Instead, let's make a kind of upside-down teeter-totter that
pivots in the middle and has TWO of those El Cheepo ten-inchers on
each end. For energy absorption we'll strap the front part of the
teeter-totter to the landing gear upright with some bungee cord. Now
when the aft pair of wheels kisses the earth the weight of the plane
will cause the teeter-totter to pivot around the mid-point until all
four wheels are on the ground. NOW we've got a landing gear that's
got a foot-print the size of a DC-3 and the whole damn thing only
costs about $20 per side.

Weight? Probably kinda heavy; the wheel part is stamped steel and
we've got the upright and the teeter-totter to think about.
Cost? Cheap, as in Durt Cheep. Each wheel is only five bux. The
bearings are trash -- we'll want to replace those as soon as we
receive the wheels.
Brakes? Nothing comes to mind other than scrubbers -- the sort of
thing that rubs against the rubber tire. But as for foot-print, we've
got an alighting system that's good for everything from beach sand to
muskeg.

One of the big down-sides is that this arrangement is only good for
something like the Teenie Two. But wait a minute... what if we were
satisfied with only TWO wheels per side. Then we could go ahead and
rig it for a tail-dragger such as Bert Sisler's 'Cygnet' or any other
similar design.

For now it's just a thought. I was about to cut metal when they
decided I had cancer. Ever since then I've been sorta preoccupied.

-R.S.Hoover

NOTE: 10" pneumatic tire w/tube $4.99, 30900-0VGA (10" Inner Tube
$3.49 38354-4VGA)

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PS -- As for my canes, I've got two of them. The first one is named
'Kane' and is made out of aluminum.
The second came along after my wife saw me struggling to keep up with
her in the parking lot outside the cancer/x-ray place. Once you get
inside they got wheel chairs and an elevator and all kinds of good
stuff but the trick is getting there, which is damn hard to do with
only one cane or Kane.

On Sun, 16 Nov 2008 19:32:47 -0800 (PST), "
wrote:

To All:

Want a cheap tire & wheel? You can get a 10" tire & wheel for a 5/8"
axle for less than $5 (!!) (see the closing NOTES). And along about
here you'll discover there's a bit more to your alighting system than
energy absorption. For example, if your tire is too narrow it's
liable to sink into the soft earth and simply stop rotating. Of
course, the airplane will continue rolling right along... but with the
wheels locked to the earth, the airplane will prescribe a graceful
outside loop, prying the wheels free of the soft earth as the airplane
comes to rest on its back, a position that's more embarrassing than
dangerous. Roll it back up-right, buy yourself a new propeller and
you're pretty much good to go, if you're willing to ignore the risk of
a cracked crankshaft or damaged rudder hinges.


phalse economy ol' fruit.
the rubber in the tyres is soft and will scrub out in no time.
experience of a number of friends is that you'll get less than 4 hours
serviceable life out of them.

trelleborg 4.00 x 4's are a true blue aero tyre and are superb by
comparison.

Stealth (ol' snake unda the verandah) Pilot

Years ago a friend designed and certified a walking-beam landing gear
for a Super Cub so it could go just about anywhere. It had a bungeed
beam, the four wheels and NO tailwheel. The bungee was strong enough
to keep the tail off the ground and the aft mains were about where
trike mains would be.
But it was heavy and draggy and hard to steer and I never saw
another one fly with it. The backwoods bushplanes all use the huge
tundra tires.

I *think* Asuza, the makers of ultralight wheels and brakes, also
make go-kart wheels and brakes for much less money. And they're
probably the same thing as those sold for aircraft use. I need to
chase that down for my Hummelbird...

Some guys have used wheelbarrow tires and wheels. Cheap, too. Are
they too big for the Chugger? And I think someone is making 6"
handcart wheels/tires, which would be ideal for the Chugger.

Dan

wrote in message ...
To All:

PS -- As for my canes, I've got two of them. The first one is named
'Kane' and is made out of aluminum.
The second came along after my wife saw me struggling to keep up with
her in the parking lot outside the cancer/x-ray place. Once you get
inside they got wheel chairs and an elevator and all kinds of good
stuff but the trick is getting there, which is damn hard to do with
only one cane or Kane.


Name the other one Candy - thinking of Christmas now, the next goal...

Stealth Pilot wrote:

the rubber in the tyres is soft and will scrub out in no time.
experience of a number of friends is that you'll get less than 4 hours
serviceable life out of them.


How much taxiing you planning on doing!! Well, I guess you would be
taxiing around more than most, seeing as how you've no brakes. (I kid!
I kid!)

Seriously, with the load spread out over 8 wheels (4 per side), and the
small amount of time spent taxing at significant speeds, 4 hours is a
long time.

On Nov 21, 9:25*pm, Ernest Christley wrote:

Seriously, with the load spread out over 8 wheels (4 per side), and the
small amount of time spent taxing at significant speeds, 4 hours is a
long time.
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Every new idea REQUIRES its pros and cons as a fundamental part of the
selection process. But a forum such as this is not the place to
explore those variables, since the decision must be based on actual
use. However, the ease with which a tire can be replaced would surely
make this particular point moot.

-R.S.Hoover

On Fri, 21 Nov 2008 22:28:04 -0800 (PST), "
wrote:

On Nov 21, 9:25*pm, Ernest Christley wrote:

Seriously, with the load spread out over 8 wheels (4 per side), and the
small amount of time spent taxing at significant speeds, 4 hours is a
long time.
-------------------------------------------------------------------------------------------------------

Every new idea REQUIRES its pros and cons as a fundamental part of the
selection process. But a forum such as this is not the place to
explore those variables, since the decision must be based on actual
use. However, the ease with which a tire can be replaced would surely
make this particular point moot.

-R.S.Hoover

not a moot point at all since a tyre blow out on landing can be fatal.

I have personally seen the tyre wear on the tyres that the guys were
trying on normal two seat ultralights and at 5 hours of normal flying
use they were stuffed. my comment is based on actual observation of
actual tyres in actual normal use.

Trelleborg Queensland Rubber can supply superb made for aviation
tyres.they arent that expensive.
my 5.00 x 5's last hundreds of hours over many years.
I think they work out to be cheaper if you compared the number of
cheap tyres you'd need to my one supposedly expensive tyre.

however ymmv.
Stealth Pilot

"Stealth Pilot" wrote in message
...
|
| not a moot point at all since a tyre blow out on landing can be fatal.
|

Here we go again.

Should a blow out be a big deal, if you are not using your brakes to stop?

On Nov 22, 4:29*am, Stealth Pilot
wrote:

not a moot point at all since a tyre blow out on landing can be fatal.
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Dear Stealth,

I'm glad you brought up that point.

The main gear I described would have four tires (tyres) per side.
Initial touch-down would be upon the rear-most pair. If one tire of
the rear-most pair blew-out on touch down, in theory you'd still have
the other to bear the load. If BOTH tires were to blow, their rims
would still be in place and would cause the front-most pair to come
into play.

In the ultimate 'worse-case' scenario, all four (!) tires would blow,
leaving you with the four steel wheels to complete the landing.

-R.S.Hoover

On Sun, 23 Nov 2008 19:52:46 -0600, "Maxwell" #$$9#@%%%.^^^ wrote:


"Stealth Pilot" wrote in message
.. .
|
| not a moot point at all since a tyre blow out on landing can be fatal.
|

Here we go again.

Should a blow out be a big deal, if you are not using your brakes to stop?


Brakes or no brakes, a blown tire ACTS LIKE brakes and WILL cause
ground handling problems. On a "real plane" where the wheel that
stears is way out back, it is even more critical.

Ground loops are no fun.