Primary Glider Drawings

On Oct 4, 11:35*am, Tech Support wrote:

Veeduber

What would it take to convert a primary into a basic soaring machine
(35+ to 1)?
-----------------------------------------------------------------------
Dear John,

I don't know. But I DO know you're comparing apples to
orangutans :-) The subject is Primary Gliders. Their poor glide
ratio -- typically about 8:1 -- is by DESIGN. That is what's needed
to fulfill their mission, which is to expose a fledgling pilot to 3-
axis controls and introduce them to the mechanics of landing.

You would probably find the syllabus used by early flight-training
programs to be of considerable interest.

-R.S.Hoover

On Mon, 06 Oct 2008 13:34:46 +1000, Michael Henry
wrote:

Tech Support wrote:
Sure nice to have so many comments that are mostly relevant to thread
and beginners glider.

Hear hear!!!

I was thinking about a wing that would support a decently high L/D and
a simple enclosure around pilot to reduce his flat plate drag, built
on a primary glider fuselage frame.

Build time 500 hours or less and transportable home. I'm in my high
80's and don't have 'time' left to build a 10 year project.

What you're describing is the Compact 110 (defunct):

http://home.ptd.net/~jlbaker/compact110.htm

...or the ULF-1:

http://www.eel.de/english/ulf-1_description.htm
************************************************** ***********************

Michael

In the ball park of what I was talking about. Will take to bed with me
and look and think on data of those who have gone before me.

Tnx

Big John

Which also linked to . . .

the Sandlin Bug
(Basic Ultralight Glider)

http://home.att.net/~m--sandlin/bug.htm

Perhaps nothing except the basic fundamental understanding of WHAT SNIP
MEANS.


Veeduber

What would it take to convert a primary into a basic soaring machine
(35+ to 1)?.

Perhaps nothing except the basic fundamental understanding of WHAT SNIP
MEANS.


--
"It is the mark of an educated mind to be able to entertain a thought
without accepting it."
--Aristotle

Perhaps nothing except the basic fundamental understanding of WHAT SNIP
MEANS.


35 to 1 and open cockpit don't coexist. Light weigh does not improve
glider ratio. In order to get anything near 35 to 1 in a homebuilt you
must build something like my Schreder HP-14.
(http://www.soaridaho.com/Schreder/HP-14/N990/N990.html)

Wayne
http://www.soaridaho.com/Schreder

"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..

"Peter Dohm" wrote in message
news
"Bill Daniels" bildan@comcast-dot-net wrote in message
...
Weight in a glider is a double edged sword and never simple. In fact,
it can add to L/D. For example, my Nimbus 2C has an L/D max of 47:1 at
1000 pounds and 49:1 at 1433 pounds. The difference in L/D max is due
to a higher Reynolds number at the higher best L/D airspeed with the
higher weight.

That extra weight is ballast water in wing tanks. In any but the
weakest weather, that ballast dramatically increases performance. This
is shown most clearly at 100 Kts where the 1000lb GW L/D is 22.3:1 and
the 1433lb GW L/D is 31:1. But, of course, structural weight is not
jetisonable as is water ballast.

But that wasn't really my point. It was that good engineering directed
at crashworthiness is an investment in design excellence which is also
likely, but not assuredly, to increase performance. At least the two
aren't mutually exclusive. That's particularly true when the cockpit
structure is molded carbon/Kevlar which can be of any shape and might as
well be the best aerodynamic one. As near as I can determine, the
latest crashworthy cockpits don't weight any more than the old ones and
they are actually lighter than steel tubes.

Bill D

I believe that you are correct in this, and that a kevlar capsule is a
good investment.

I have not researched the matter and could be wrong; but I strongly
suspect that a many, if not most, of the dissabling leg injuries in the
old primary gliders involved easily deflected collisions rather than
"hitting a wall".

Peter
Most likely.

I know of one accident in a Schweizer 1-26A (tube and fabric) where an off
field landing resulted in a stick coming through the nose fabric severing
a leg artery. The pilot bled to death before he could get out of the
cockpit. I guess you can tell that I have no love of tube and fabric
gliders.

Bill D

This is an extreme case of the same problem that concerns me: Intrusion of
"brush" in the course of an off field landing. Obviously, in this
particular case, the shrubbery involved must have appeared to be soft enough
to be deflected by the tube and fabric structure; but the general problem
must have been nearly epidemic with the completely open seating areas of the
primary gliders.

Nothing can ever eliminate the occasional encounter with a stronger and/or
sharper than expected solid object; but a slightly flexible kevlar based
composite capsule could be a great improvement. The March racing cars used
a kevlar based capsule system about 30 years ago with considerable
success--although their earliest attempts were heavy and less than
competitive, and some developement was required.

AFAIK, kevlar has a high tensile strenght, but does not bond to the resins
in which it might be encapslated. Therefore, it will extrude under load.
That makes it a good to excellent material for safety structures and a
generally poor material for heavy load bearing structures.

Peter

"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..
snippage
Let me throw in a slightly controversial idea.

Low L/D, taken in isolation, offers no benefit whatsoever in a trainer.
In
fact, higher L/D is a safety feature that gets an inexperienced pilot back
to the runway after a bad judgement call. In spite of this, there is an
instinctive reaction among most glider pilots to inversely relate L/D and
safe handling qualities.

In a soaring environment, I think you're right. But that is not the
environment veeduber is proposing.

He's proposing a cheap "hook" to capture the attention of teenagers.
Teenagers who might not have two grand or so to shell out for glider
lessons, but might well have some sweat equity to invest in building
something that actually flies.

For this target group, it has to be something that goes together pretty
quickly. If it takes a thousand hours of construction, it isn't likely to
get started, let alone completed.

For veeduber's purposes, I think he will have achieved part of his goal if
it gets even half built. Kids will be using their heads and their hands to
solve problems.

For this environment, it's not performance that counts, but energy. With a
fairly draggy airframe, you can limit the amount of energy available to
damage the pilot.

Somewhere on Mike Sandlin's site, he remarks on this, limiting the energy by
how far up the training hill you drag the glider.

snippage

"Primary gliders" were an expedient developed in an environment that
lacked
adequate two-seat trainers. They were abandoned with great relief as soon
as usable 2-seater trainers became available. Today, there are a great
number of excellent 2-seat trainers and qualified instructors. Only a
fool
would try to learn flying in a "Primary".

I can't entirely disagree, but people learn to fly hang gliders, with
similar performance limitations, every day.
There is some tandem instruction available, and that's good. But in
general, it's not the instruction process that kills people.
A two-place primary under 155 lbs might sneak in under USHGPA's tandem
exemption, here in the U.S. Maybe.


Tim Ward

On Sun, 5 Oct 2008 21:43:49 -0700 (PDT), "
wrote:

On Oct 4, 11:35*am, Tech Support wrote:

Veeduber

What would it take to convert a primary into a basic soaring machine
(35+ to 1)?
-----------------------------------------------------------------------
Dear John,

I don't know. But I DO know you're comparing apples to
orangutans :-) The subject is Primary Gliders. Their poor glide
ratio -- typically about 8:1 -- is by DESIGN. That is what's needed
to fulfill their mission, which is to expose a fledgling pilot to 3-
axis controls and introduce them to the mechanics of landing.

You would probably find the syllabus used by early flight-training
programs to be of considerable interest.

-R.S.Hoover
************************************************** ***************************


Understand ur comments but intent of my original post was to get some
ideas on size and airfoil of a wing attached to a Primary Glider
fuselage with a minimual enclosure around pilot that would permit some
basic soaring. All on the cheap and rapid build.

Lots of ideas have been expessed that shot down some of my original
ideas and others that have given me clues on how to meet my original
objectives.

Tnx to all.

Y'all have a nice day and hope you get good news on ur health.

Big John

"Tim Ward" wrote in message
...

"Bill Daniels" bildan@comcast-dot-net wrote in message
. ..
snippage
Let me throw in a slightly controversial idea.

Low L/D, taken in isolation, offers no benefit whatsoever in a trainer.
In
fact, higher L/D is a safety feature that gets an inexperienced pilot
back
to the runway after a bad judgement call. In spite of this, there is an
instinctive reaction among most glider pilots to inversely relate L/D and
safe handling qualities.

In a soaring environment, I think you're right. But that is not the
environment veeduber is proposing.

He's proposing a cheap "hook" to capture the attention of teenagers.
Teenagers who might not have two grand or so to shell out for glider
lessons, but might well have some sweat equity to invest in building
something that actually flies.

For this target group, it has to be something that goes together pretty
quickly. If it takes a thousand hours of construction, it isn't likely
to
get started, let alone completed.

For veeduber's purposes, I think he will have achieved part of his goal if
it gets even half built. Kids will be using their heads and their hands
to
solve problems.

For this environment, it's not performance that counts, but energy. With
a
fairly draggy airframe, you can limit the amount of energy available to
damage the pilot.

Somewhere on Mike Sandlin's site, he remarks on this, limiting the energy
by
how far up the training hill you drag the glider.

snippage

"Primary gliders" were an expedient developed in an environment that
lacked
adequate two-seat trainers. They were abandoned with great relief as
soon
as usable 2-seater trainers became available. Today, there are a great
number of excellent 2-seat trainers and qualified instructors. Only a
fool
would try to learn flying in a "Primary".

I can't entirely disagree, but people learn to fly hang gliders, with
similar performance limitations, every day.
There is some tandem instruction available, and that's good. But in
general, it's not the instruction process that kills people.
A two-place primary under 155 lbs might sneak in under USHGPA's tandem
exemption, here in the U.S. Maybe.


Tim Ward



OK, but don't build one, buy one. There are a few around. Take it out to a
hill or dry lake and try flying it. This is also done on occasion. What
you won't do is fly it two days in a row. One day will convince just about
anybody that primaries are a really bad idea.

Primary gliders are a huge amount of work to fly - expecially if you use the
traditional bungee launch method which is really the only safe way to fly
one. Aero tow or winch launch is terrfying in a primary - although this is
also done on occasion. (But rarely twice in a lifetime by the same pilot.)

To fly one as it was intended, you need a huge grassy slope that is slightly
shallower than the glide ratio of the primary. The bungee launch will get
the glider to just above stall speed a couple of feet above the ground. If
the pilot can hold the exact best L/D airspeed and keep it perfectly
coordinated, he will be rewarded with a glide of a couple of hundred yards -
maybe 30 seconds of airtime. If he deviates in any way from perfection, the
glider will quickly settle into the grass. If you have 15 - 20 knots of
wind up the slope, the instructor can run along side shouting instructions.
Then everybody gets to haul it back up the slope. All this exercise will
achieve about ten flights a day but it WILL get you in shape.
See: http://www.youtube.com/watch?v=B6-EeuEi-KY
See: http://www.youtube.com/watch?v=BgBJ52L-Rao

I have a better idea that fits well with the homebuilder ethic. Build a
winch.
See: http://groups.yahoo.com/group/winchengineer/files/

The really big cost in learning to fly gliders is aero tow. It averages
about $50 for a 15 minute flight. Add instructor and glider rental and it's
not unusual to see $250 and hour. Multi-engine training is cheaper.
Winches can reduce launch costs to $5 and glider training rates to ~$50/hr.
Certified glider trainers aren't expensive if you can keep the utilization
high.

And I GUARANTEE it attracts young people. You can't buy a ride like that at
Disneyland.
See: http://www.youtube.com/watch?v=UOp_EsplxDM

Bill Daniels