Which Tow Vehicle

Larry, I agree.
I drove at one point an extended version of the old Aero Star. This
combination was good for about 60m/h max no wind, with the same sort
of trailers I am towing now. This was ok for the odd retrieve and
contest.


The points you raised were also the things I was looking for in a new
Mini Van. But only one Mini Van met those criteria, the Honda Odyssey.
Low C of G, short coupled between ball hitch and rear independent
suspension. Powerful and fun to drive, comfortable and reasonably good
on gas. In any case I found it handled the Schreder trailer as well as
a Cobra unit, The Schreder trailer Van combination use more gas then
the cobra trailer combo.

With the currant cobra trailer I noted a difference, even though this
one is newer and has shocks. It was not as stable as the other cobra
trailer. Lucky for me I marked my drive way for my first cobra
trailer wheels. I noticed that the trailer was to close to the
garage door. It turns out the wheels are to far forward by at least
10". Also the trailer hitch would not stay down when the trailer is
empty, which all other trailers did with about 15 lb down force
empty. I think that would explain the slightly less stable set-up
In time I will move the axle.

Udo


and everything will be fine" approaches. In addition to the obvious
things that have been written about in this thread (vehicle weights,
tongue weights, tires and tire pressures, etc.) there are _many_ other
significant factors in play. To name a few (very incomplete list):

--moment arm of the hitch ball to rear axle of the car (one of the most
significant from my experience)

--suspension dynamics of tow vehicle

--aerodynamic shape of the trailer

--combined aerodynamic interactions between tow vehicle and trailer

--environmental considerations where you tow ( prevailing wind, etc.)

--proximity to field effects of passing vehicles, etc.

--necessary or desired speed for trip

-- on and on.......

So to say that "Towing is simple. Follow these rules, and your rig will
be stable in all conditions and not need stabiliser hitch." is in my
experience a gross oversimplification.

Larry
-

Tom Gardner wrote:
Martin Gregorie wrote in news:kg50u4-
:

I'd never knock the series II or III. Mine did a London-India out and
return in 10 months without any problems apart from a tendency to
consume speedometers that I never got to the bottom of, a clutch change
in Mysore and a clutch slave cylinder replacement in Turkey.

I had a series II with a 4litre perkins diesel engine.
Yes, it would pull the skin off custard, and yes the
engine mountings and transmission spiders were problematical.

Mine had the trad. 4 cyl 2.25 litre petrol engine and it would happily
pull skin off custard, but slowly. However, the engine mountings and
transmission were plenty strong enough for that small donk.

The standard diesel was a dog (a diesel version of the four potter,
gutless and noisy). The other standard engine, the 2.6 litre petrol
straight six was also bad news. It was all revs and no torque and very
thirsty with it.

However, when we hit Asia I did rather wish I had the diesel because
that was never more than half the price of petrol from the Bosphorus
east and at that time [1] in Iran it was 1/5 the price of petrol. I had
at least fitted an electronic ignition that moved the beast up from 16
mpg to 18 mpg.

Mine seemed to have a lot of parts in common with Minis,
e.g. rear lights and driver's seat.

Mine was the 10-12 seat wagon version with up-market seating for five. I
don't recall any Mini parts but it was a long time ago.

[1] 1977/78 when the ******* Shah and his nasty Savak were still there.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

On Oct 12, 3:57 pm, "01-- Zero One" wrote:
So to say that "Towing is simple. Follow these rules, and your rig will
be stable in all conditions and not need stabiliser hitch." is in my
experience a gross oversimplification.

Think we'll have to agree to disagree - but I'd like to know of
examples where these guidelines were met, but the rig was still
unstable.

One thing I don't mention which could be called an
"oversimplification" is weight distribution within the trailer, mass
should be concentrated low and over the axle. However you don't
usually have much choice about that with a glider.


Dan

On Oct 11, 9:51 pm, Eric Greenwell wrote:
Dan G wrote:
We've discussed this one before, and there is no evidence suggesting 7%
is appropriate for glider trailers, as the number comes from a study of
caravans (travel trailers). The more common numbers are 10%-15%, also
with the requirement to stay within the vehicle and hitch load
specifications.

I won't disagree, though I'm not sure glider trailers and caravans are
*that* different. I guess the real "rule" is simply having plenty of
weight on the hitch, but not more than the tow vehicle is rated for.


The list does not include the most important factor: speed. Every tow
vehicle and trailer is stable below some speed; unfortunately, there
isn't any safe and easy way to determine this that I know of. I do
suspect most trailer accidents from loss of control could be avoided if
the driver had paid attention to signs of instability in the past, and
drove more slowly as a result.

Isn't that common sense, really?


Dan

On Oct 11, 3:41 pm, Eric Greenwell wrote:
Dan G wrote:

Crash-worthiness and energy absorbtion is ENTIRELY down to design, not

material.

The major glider manufacturers don't agree with this: take look at the
cockpit of a Schleicher glider, for example, and see how little of it is
carbon fiber. Aramids and glass fiber absorb energy better than carbon
fiber, and so a designer will use them if it is possible.

Didn't I say it's design, not material? :-) However Shleicher do
actually use carbon fibre reinforcements on at least some of their
cockpits - check their website:

http://www.alexander-schleicher.de/p...g29_main_e.htm

Lange might do too - they say they use "F1 materials" for the cockpit
of the Antares.

The underlying point is that you want the safety cell - whether car,
glider or even train cab - to be extremely strong to resist collapse,
with deformable parts elsewhere to absorb energy and hence lower peak
G on the occupant.


Dan

Dan G wrote:
On Oct 11, 9:51 pm, Eric Greenwell wrote:
Dan G wrote:
We've discussed this one before, and there is no evidence suggesting 7%
is appropriate for glider trailers, as the number comes from a study of
caravans (travel trailers). The more common numbers are 10%-15%, also
with the requirement to stay within the vehicle and hitch load
specifications.

I won't disagree, though I'm not sure glider trailers and caravans are
*that* different.

Even glider trailers can differ markedly from one another, so it's no
stretch to imagine caravans (less than half the length, 30% wider, and
twice as tall as a glider trailer of the same weight) might act very
differently behind the same tow vehicle.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Dan G wrote:
On Oct 11, 3:41 pm, Eric Greenwell wrote:
Dan G wrote:

Crash-worthiness and energy absorbtion is ENTIRELY down to design, not

material.
The major glider manufacturers don't agree with this: take look at the
cockpit of a Schleicher glider, for example, and see how little of it is
carbon fiber. Aramids and glass fiber absorb energy better than carbon
fiber, and so a designer will use them if it is possible.

Didn't I say it's design, not material? :-) However Shleicher do
actually use carbon fibre reinforcements on at least some of their
cockpits - check their website:

http://www.alexander-schleicher.de/p...g29_main_e.htm

All Schleicher gliders, beginning with the ASW 24, use carbon fiber
rails on the cockpit sill, but even on the ASG 29, most of the cockpit
structure is still glass fiber and aramid composite. Gerhard Waibel had
an excellent article describing the design of the ASW 24 cockpit,
considered the first of the modern "safety cockpits", in Soaring
Magazine about 20 years ago, and also more recent articles in Technical
Soaring. Those articles can explain the design of an improved cockpit
much better than I can here.


Lange might do too - they say they use "F1 materials" for the cockpit
of the Antares.

The underlying point is that you want the safety cell - whether car,
glider or even train cab - to be extremely strong to resist collapse,
with deformable parts elsewhere to absorb energy and hence lower peak
G on the occupant.

To the contrary, Schleicher and the others have chosen not to use a
"safety cell" design. The nose would have to extend several feet beyond
were it does now to have sufficient crush distance, and they do not
believe pilots will buy such a glider.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Lange might do too - they say they use "F1 materials" for the cockpit
of the Antares.

The underlying point is that you want the safety cell - whether car,
glider or even train cab - to be extremely strong to resist collapse,
with deformable parts elsewhere to absorb energy and hence lower peak
G on the occupant.

To the contrary, Schleicher and the others have chosen not to use a
"safety cell" design. The nose would have to extend several feet beyond
were it does now to have sufficient crush distance, and they do not
believe pilots will buy such a glider.

Lange does use a crush zone, and it certainly did not
require "several feet longer fuselage" for Antares. See:
http://www.lange-flugzeugbau.de/htm/...0e/safety.html
The crushable nose-cone is a separate part from the
remainder of the safety cockpit, attached late in the
manufacturing. I'll try get some pictures on my
web site...

See ya, Dave "YO"

Just to clear some things up:
The Antares family of gliders has been designed with
a safety cell and energy absorbing nosecone. In order
to facilitate this, the cockpit was extended forward
at approximately zero aerodynamic loss. The whole cockpit
is using a special carbon-carbon technology (no kevlar
or dyneema), and was designed mainly by a F1 crash
structure designer. The safety cell has been design
to fail only after there is nothing left to save inside
(due to extreme g-loads).

Fitting the lower part of the pilot into the crumble-zone
is, in my personal opinion, not the best of ideas,
as damage to the feet tend to take extremely long to
heal.

Andor



At 02:18 13 October 2007, Eric Greenwell wrote:
Dan G wrote:
On Oct 11, 3:41 pm, Eric Greenwell wrote:
Dan G wrote:

Crash-worthiness and energy absorbtion is ENTIRELY
down to design, not

material.
The major glider manufacturers don't agree with this:
take look at the
cockpit of a Schleicher glider, for example, and see
how little of it is
carbon fiber. Aramids and glass fiber absorb energy
better than carbon
fiber, and so a designer will use them if it is possible.

Didn't I say it's design, not material? :-) However
Shleicher do
actually use carbon fibre reinforcements on at least
some of their
cockpits - check their website:

http://www.alexander-schleicher.de/p...sg29_main_e.ht
m

All Schleicher gliders, beginning with the ASW 24,
use carbon fiber
rails on the cockpit sill, but even on the ASG 29,
most of the cockpit
structure is still glass fiber and aramid composite.
Gerhard Waibel had
an excellent article describing the design of the ASW
24 cockpit,
considered the first of the modern 'safety cockpits',
in Soaring
Magazine about 20 years ago, and also more recent articles
in Technical
Soaring. Those articles can explain the design of an
improved cockpit
much better than I can here.


Lange might do too - they say they use 'F1 materials'
for the cockpit
of the Antares.

The underlying point is that you want the safety cell
- whether car,
glider or even train cab - to be extremely strong
to resist collapse,
with deformable parts elsewhere to absorb energy and
hence lower peak
G on the occupant.

To the contrary, Schleicher and the others have chosen
not to use a
'safety cell' design. The nose would have to extend
several feet beyond
were it does now to have sufficient crush distance,
and they do not
believe pilots will buy such a glider.

--
Eric Greenwell - Washington State, USA
* Change 'netto' to 'net' to email me directly
* 'Transponders in Sailplanes' http://tinyurl.com/y739x4
* 'A Guide to Self-launching Sailplane Operation' at
www.motorglider.org

wrote:

To the contrary, Schleicher and the others have chosen not to use a
"safety cell" design. The nose would have to extend several feet beyond
were it does now to have sufficient crush distance, and they do not
believe pilots will buy such a glider.

Lange does use a crush zone, and it certainly did not
require "several feet longer fuselage" for Antares. See:
http://www.lange-flugzeugbau.de/htm/...0e/safety.html
The crushable nose-cone is a separate part from the
remainder of the safety cockpit, attached late in the
manufacturing.

It looks like a good design; still, an additional 4" over a "normal"
fuselage is not much compared to the several feet of crush zone
available in an automobile. Is it intended that the cockpit function in
the "safety cell" manner that Dan G was describing, or is it designed to
crumple progressively to absorb energy, like the Schleicher cockpits?

I wish there indpendent tests of glider crash protection that were
released to the public, because it is very difficult for us to determine
the effectiveness of a design, especially new designs that have not had
any crashes yet.

I'll try get some pictures on my
web site...

I'd love to see those.


--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org