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Wanting to start a new glider club



 
 
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  #1  
Old January 1st 19, 03:13 PM posted to rec.aviation.soaring
Martin Gregorie[_6_]
external usenet poster
 
Posts: 699
Default Wanting to start a new glider club

On Mon, 31 Dec 2018 19:21:45 -0800, WB wrote:

There is nothing new under the sun when it comes to ground launching,
auto tow, winch, whatever. It's pretty much all been tried. Derek Piggot
wrote a book that is a great resource for learning about ground launch
in it's many forms. Unfortunately, it appears to be out of print.

ITYM "Gliding - A handbook on Soaring Flight"

Edition 7, which I have (blue cover showing a DG-800B with its motor
out), has two chapters on ground launching and is currently on offer from
Amazon for $3.60. His books may be out of print, but you can easily find
copies. Amazon even has a Derek Piggott author page.


--
Martin | martin at
Gregorie | gregorie dot org
  #2  
Old January 2nd 19, 07:59 AM posted to rec.aviation.soaring
John Foster
external usenet poster
 
Posts: 354
Default Wanting to start a new glider club

On Tuesday, January 1, 2019 at 8:13:46 AM UTC-7, Martin Gregorie wrote:
On Mon, 31 Dec 2018 19:21:45 -0800, WB wrote:

There is nothing new under the sun when it comes to ground launching,
auto tow, winch, whatever. It's pretty much all been tried. Derek Piggot
wrote a book that is a great resource for learning about ground launch
in it's many forms. Unfortunately, it appears to be out of print.

ITYM "Gliding - A handbook on Soaring Flight"

Edition 7, which I have (blue cover showing a DG-800B with its motor
out), has two chapters on ground launching and is currently on offer from
Amazon for $3.60. His books may be out of print, but you can easily find
copies. Amazon even has a Derek Piggott author page.


--
Martin | martin at
Gregorie | gregorie dot org


That books looks promising. Thanks for the link.

With regard to the pulley: what diameter would it need to be? I've seen somewhere that a higher grade of UHMWPE--New England STS-12 (formerly Endura 12), recommends a sheave:rope diameter ratio of 8:1. That would mean for a 1/8" rope, one could get away with a sheave of only 1" in a pulley. Somehow that just doesn't seem like a good idea in this application though, but I don't know. So I'm asking.

If this were the case then, one could simply order these items off Amazon and be done with it:
https://www.amazon.com/Smittybilt-27...s=snatch+block
https://www.amazon.com/dp/B01I25Z5F4...v_ov_lig_dp_it
  #3  
Old January 2nd 19, 09:39 AM posted to rec.aviation.soaring
Frank Whiteley
external usenet poster
 
Posts: 2,099
Default Wanting to start a new glider club

On Wednesday, January 2, 2019 at 12:59:47 AM UTC-7, John Foster wrote:
On Tuesday, January 1, 2019 at 8:13:46 AM UTC-7, Martin Gregorie wrote:
On Mon, 31 Dec 2018 19:21:45 -0800, WB wrote:

There is nothing new under the sun when it comes to ground launching,
auto tow, winch, whatever. It's pretty much all been tried. Derek Piggot
wrote a book that is a great resource for learning about ground launch
in it's many forms. Unfortunately, it appears to be out of print.

ITYM "Gliding - A handbook on Soaring Flight"

Edition 7, which I have (blue cover showing a DG-800B with its motor
out), has two chapters on ground launching and is currently on offer from
Amazon for $3.60. His books may be out of print, but you can easily find
copies. Amazon even has a Derek Piggott author page.


--
Martin | martin at
Gregorie | gregorie dot org


That books looks promising. Thanks for the link.

With regard to the pulley: what diameter would it need to be? I've seen somewhere that a higher grade of UHMWPE--New England STS-12 (formerly Endura 12), recommends a sheave:rope diameter ratio of 8:1. That would mean for a 1/8" rope, one could get away with a sheave of only 1" in a pulley. Somehow that just doesn't seem like a good idea in this application though, but I don't know. So I'm asking.

If this were the case then, one could simply order these items off Amazon and be done with it:
https://www.amazon.com/Smittybilt-27...s=snatch+block
https://www.amazon.com/dp/B01I25Z5F4...v_ov_lig_dp_it


8 inches is okay, but there are other reverse pulley considerations. If you want the wheel to track the glider climb and drift, as in the old Cotswold system, a larger diameter is probably better. It was an effective 50" radius using using small rollers to reduce any stored energy in the system, which was an issue with the Essex GC system. With UHMWPE rope, you want to eliminate both stored energy and the ability for slack rope to tuck into any gaps or result in loops that might impact on the ground or equipment. Larger rope types might help with some of this, but there are always compromises of performance and price. UV resistence, abrasive resistence, fatigue (as a result of loading cycles), and ease of handling (including splicing) are all considerations.

This might be a suitable substitute for UHMWPE ropes for reverse pulley, http://www.novabraid.com/rope/oletec-12/ though they make no claims on abrasion resistance. 3/8" might be so heavy as to cause abrasive issues. This was true on the Cotswold system using solid wire. 10 gauge was heavy enough to cause excessive wear on the "memory loops" on the wire, so 13 gauge was found to give the best performance. Use of solid wire is not recommended at public use airports wherever you are because a large clear zone is needed in case of wire breaks. Many of these new ropes have negligible stretch, thus no recoil issues. Solid wire and steel wire ropes have significant recoil hazards.

Frank Whiteley
  #4  
Old January 2nd 19, 07:01 PM posted to rec.aviation.soaring
Chris Rowland[_2_]
external usenet poster
 
Posts: 45
Default Wanting to start a new glider club

I learnt to glide and instruct in the late 1960s and 70s at a club that
used autotow and would suggest that if you are startng up and your site can
manage the rope issues with ground based cable launching then start with
straight autotow. 1500' to 1800' of cable and a pick up truck. It's the
simplest system. The turn round time will be slower but to start with that
won't be an issue.

We tried reverse pulley and couldn't make it work reliably because it was
very easy to launch too far and what happened then was that the cable
broke, thus making the whole thing a mess.

If you do then you will find that your pulley assembly needs to move about
two axes, both horizontally and vertically. The vertical axis handles the
situation where the glider is to one side of the runway.

But if the airfield is being used by other air traffic I'm not sure if any
wire launch system will work because of the risk to things such as lights
and the risks of mixing aircraft and cables.

Chris

At 09:39 02 January 2019, Frank Whiteley wrote:
On Wednesday, January 2, 2019 at 12:59:47 AM UTC-7, John Foster wrote:
On Tuesday, January 1, 2019 at 8:13:46 AM UTC-7, Martin Gregorie wrote:
On Mon, 31 Dec 2018 19:21:45 -0800, WB wrote:
=20
There is nothing new under the sun when it comes to ground

launching,
auto tow, winch, whatever. It's pretty much all been tried. Derek

Pig=
got
wrote a book that is a great resource for learning about ground

launc=
h
in it's many forms. Unfortunately, it appears to be out of print.

ITYM "Gliding - A handbook on Soaring Flight"
=20
Edition 7, which I have (blue cover showing a DG-800B with its

motor=20
out), has two chapters on ground launching and is currently on offer

fr=
om=20
Amazon for $3.60. His books may be out of print, but you can easily

fin=
d=20
copies. Amazon even has a Derek Piggott author page.=20
=20
=20
--=20
Martin | martin at
Gregorie | gregorie dot org

=20
That books looks promising. Thanks for the link.
=20
With regard to the pulley: what diameter would it need to be? I've

seen
=
somewhere that a higher grade of UHMWPE--New England STS-12 (formerly
Endur=
a 12), recommends a sheave:rope diameter ratio of 8:1. That would mean
for=
a 1/8" rope, one could get away with a sheave of only 1" in a pulley.
Som=
ehow that just doesn't seem like a good idea in this application though,
bu=
t I don't know. So I'm asking.
=20
If this were the case then, one could simply order these items off

Amazon=
and be done with it:

https://www.amazon.com/Smittybilt-27...k/dp/B003CG9P=
IC/ref=3Dsr_1_3?ie=3DUTF8&qid=3D1546415068&sr=3D8-3&keywords=3Dsnatch+block

https://www.amazon.com/dp/B01I25Z5F4...&colid=3D1CG4=
T3YDCVWF8&psc=3D0&ref_=3Dlv_ov_lig_dp_it

8 inches is okay, but there are other reverse pulley considerations. If
yo=
u want the wheel to track the glider climb and drift, as in the old
Cotswol=
d system, a larger diameter is probably better. It was an effective 50"
ra=
dius using using small rollers to reduce any stored energy in the system,
w=
hich was an issue with the Essex GC system. With UHMWPE rope, you want

to
=
eliminate both stored energy and the ability for slack rope to tuck into
an=
y gaps or result in loops that might impact on the ground or equipment.
La=
rger rope types might help with some of this, but there are always
compromi=
ses of performance and price. UV resistence, abrasive resistence,

fatigue
=
(as a result of loading cycles), and ease of handling (including

splicing)
=
are all considerations.

This might be a suitable substitute for UHMWPE ropes for reverse pulley,
ht=
tp://www.novabraid.com/rope/oletec-12/ though they make no claims on
abrasi=
on resistance. 3/8" might be so heavy as to cause abrasive issues. This
w=
as true on the Cotswold system using solid wire. 10 gauge was heavy
enough=
to cause excessive wear on the "memory loops" on the wire, so 13 gauge
was=
found to give the best performance. Use of solid wire is not

recommended
=
at public use airports wherever you are because a large clear zone is
neede=
d in case of wire breaks. Many of these new ropes have negligible
stretch,=
thus no recoil issues. Solid wire and steel wire ropes have significant
r=
ecoil hazards.

Frank Whiteley


  #5  
Old January 2nd 19, 09:26 PM posted to rec.aviation.soaring
John Young[_3_]
external usenet poster
 
Posts: 1
Default Wanting to start a new glider club


Peter Whitehead gave some information on an earlier post showing a
reverse pulley launch but had no video of the business end - I can
add this here and hope it is of some help.

https://www.youtube.com/watch?v=Q0rv1zOmyWg&t=51s

Peter is the best contact for technical information regarding
equipment used - the bearings on the first trials were not up to the
speed and were replaced due to overheating.
Overall the results were superb for an expatiation from another new
site in the Lake district.
JY



At 19:01 02 January 2019, Chris Rowland wrote:
I learnt to glide and instruct in the late 1960s and 70s at a club tha
used autotow and would suggest that if you are startng up and

your site ca
manage the rope issues with ground based cable launching then

start wit
straight autotow. 1500' to 1800' of cable and a pick up truck. It's

th
simplest system. The turn round time will be slower but to start

with tha
won't be an issue.

We tried reverse pulley and couldn't make it work reliably because

it wa
very easy to launch too far and what happened then was that the

cabl
broke, thus making the whole thing a mess.

If you do then you will find that your pulley assembly needs to

move abou
two axes, both horizontally and vertically. The vertical axis handles

th
situation where the glider is to one side of the runway.

But if the airfield is being used by other air traffic I'm not sure if an
wire launch system will work because of the risk to things such as

light
and the risks of mixing aircraft and cables.

Chris

At 09:39 02 January 2019, Frank Whiteley wrote:
On Wednesday, January 2, 2019 at 12:59:47 AM UTC-7, John

Foster wrote:
On Tuesday, January 1, 2019 at 8:13:46 AM UTC-7, Martin

Gregorie wrote:
On Mon, 31 Dec 2018 19:21:45 -0800, WB wrote:
=20
There is nothing new under the sun when it comes to

groun
launching,
auto tow, winch, whatever. It's pretty much all been tried.

Derek
Pig=
got
wrote a book that is a great resource for learning about

ground
launc=
h
in it's many forms. Unfortunately, it appears to be out of

print.

ITYM "Gliding - A handbook on Soaring Flight"
=20
Edition 7, which I have (blue cover showing a DG-800B with

it
motor=20
out), has two chapters on ground launching and is currently

on offer
fr=
om=20
Amazon for $3.60. His books may be out of print, but you

can easily
fin=
d=20
copies. Amazon even has a Derek Piggott author page.=20
=20
=20
--=20
Martin | martin at
Gregorie | gregorie dot org
=20
That books looks promising. Thanks for the link.
=20
With regard to the pulley: what diameter would it need to be?

I'v
seen
=
somewhere that a higher grade of UHMWPE--New England STS-

12 (formerly
Endur=
a 12), recommends a sheave:rope diameter ratio of 8:1. That

would mean
for=
a 1/8" rope, one could get away with a sheave of only 1" in a

pulley.
Som=
ehow that just doesn't seem like a good idea in this application

though,
bu=
t I don't know. So I'm asking.
=20
If this were the case then, one could simply order these items

off
Amazon=
and be done with it:

https://www.amazon.com/Smittybilt-27...versal-Snatch-

Block/dp/B003CG9P=
IC/ref=3Dsr_1_3?ie=3DUTF8&qid=3D1546415068&sr=3D8-

3&keywords=3Dsnatch+block

https://www.amazon.com/dp/B01I25Z5F4/?

coliid=3DIC5446KT2CY9R&colid=3D1CG4=
T3YDCVWF8&psc=3D0&ref_=3Dlv_ov_lig_dp_it

8 inches is okay, but there are other reverse pulley

considerations. If
yo=
u want the wheel to track the glider climb and drift, as in the old
Cotswol=
d system, a larger diameter is probably better. It was an

effective 50"
ra=
dius using using small rollers to reduce any stored energy in the

system,
w=
hich was an issue with the Essex GC system. With UHMWPE

rope, you wan
to
=
eliminate both stored energy and the ability for slack rope to tuck

into
an=
y gaps or result in loops that might impact on the ground or

equipment.
La=
rger rope types might help with some of this, but there are

always
compromi=
ses of performance and price. UV resistence, abrasive resistence

fatigue
=
(as a result of loading cycles), and ease of handling (includin

splicing)
=
are all considerations.

This might be a suitable substitute for UHMWPE ropes for reverse

pulley,
ht=
tp://www.novabraid.com/rope/oletec-12/ though they make no

claims on
abrasi=
on resistance. 3/8" might be so heavy as to cause abrasive

issues. This
w=
as true on the Cotswold system using solid wire. 10 gauge was

heavy
enough=
to cause excessive wear on the "memory loops" on the wire, so

13 gauge
was=
found to give the best performance. Use of solid wire is no

recommended
=
at public use airports wherever you are because a large clear

zone is
neede=
d in case of wire breaks. Many of these new ropes have

negligible
stretch,=
thus no recoil issues. Solid wire and steel wire ropes have

significant
r=
ecoil hazards.

Frank Whiteley




  #6  
Old January 2nd 19, 11:18 PM posted to rec.aviation.soaring
Frank Whiteley
external usenet poster
 
Posts: 2,099
Default Wanting to start a new glider club

On Wednesday, January 2, 2019 at 2:39:13 AM UTC-7, Frank Whiteley wrote:
On Wednesday, January 2, 2019 at 12:59:47 AM UTC-7, John Foster wrote:
On Tuesday, January 1, 2019 at 8:13:46 AM UTC-7, Martin Gregorie wrote:
On Mon, 31 Dec 2018 19:21:45 -0800, WB wrote:

There is nothing new under the sun when it comes to ground launching,
auto tow, winch, whatever. It's pretty much all been tried. Derek Piggot
wrote a book that is a great resource for learning about ground launch
in it's many forms. Unfortunately, it appears to be out of print.

ITYM "Gliding - A handbook on Soaring Flight"

Edition 7, which I have (blue cover showing a DG-800B with its motor
out), has two chapters on ground launching and is currently on offer from
Amazon for $3.60. His books may be out of print, but you can easily find
copies. Amazon even has a Derek Piggott author page.


--
Martin | martin at
Gregorie | gregorie dot org


That books looks promising. Thanks for the link.

With regard to the pulley: what diameter would it need to be? I've seen somewhere that a higher grade of UHMWPE--New England STS-12 (formerly Endura 12), recommends a sheave:rope diameter ratio of 8:1. That would mean for a 1/8" rope, one could get away with a sheave of only 1" in a pulley. Somehow that just doesn't seem like a good idea in this application though, but I don't know. So I'm asking.

If this were the case then, one could simply order these items off Amazon and be done with it:
https://www.amazon.com/Smittybilt-27...s=snatch+block
https://www.amazon.com/dp/B01I25Z5F4...v_ov_lig_dp_it


8 inches is okay, but there are other reverse pulley considerations. If you want the wheel to track the glider climb and drift, as in the old Cotswold system, a larger diameter is probably better. It was an effective 50" radius using using small rollers to reduce any stored energy in the system, which was an issue with the Essex GC system. With UHMWPE rope, you want to eliminate both stored energy and the ability for slack rope to tuck into any gaps or result in loops that might impact on the ground or equipment. Larger rope types might help with some of this, but there are always compromises of performance and price. UV resistence, abrasive resistence, fatigue (as a result of loading cycles), and ease of handling (including splicing) are all considerations.

This might be a suitable substitute for UHMWPE ropes for reverse pulley, http://www.novabraid.com/rope/oletec-12/ though they make no claims on abrasion resistance. 3/8" might be so heavy as to cause abrasive issues. This was true on the Cotswold system using solid wire. 10 gauge was heavy enough to cause excessive wear on the "memory loops" on the wire, so 13 gauge was found to give the best performance. Use of solid wire is not recommended at public use airports wherever you are because a large clear zone is needed in case of wire breaks. Many of these new ropes have negligible stretch, thus no recoil issues. Solid wire and steel wire ropes have significant recoil hazards.

Frank Whiteley


WRT Cotswold 50" diameter.
  #7  
Old January 3rd 19, 04:49 AM posted to rec.aviation.soaring
John Foster
external usenet poster
 
Posts: 354
Default Wanting to start a new glider club

On Wednesday, January 2, 2019 at 4:18:44 PM UTC-7, Frank Whiteley wrote:
On Wednesday, January 2, 2019 at 2:39:13 AM UTC-7, Frank Whiteley wrote:
On Wednesday, January 2, 2019 at 12:59:47 AM UTC-7, John Foster wrote:
On Tuesday, January 1, 2019 at 8:13:46 AM UTC-7, Martin Gregorie wrote:
On Mon, 31 Dec 2018 19:21:45 -0800, WB wrote:

There is nothing new under the sun when it comes to ground launching,
auto tow, winch, whatever. It's pretty much all been tried. Derek Piggot
wrote a book that is a great resource for learning about ground launch
in it's many forms. Unfortunately, it appears to be out of print.

ITYM "Gliding - A handbook on Soaring Flight"

Edition 7, which I have (blue cover showing a DG-800B with its motor
out), has two chapters on ground launching and is currently on offer from
Amazon for $3.60. His books may be out of print, but you can easily find
copies. Amazon even has a Derek Piggott author page.


--
Martin | martin at
Gregorie | gregorie dot org

That books looks promising. Thanks for the link.

With regard to the pulley: what diameter would it need to be? I've seen somewhere that a higher grade of UHMWPE--New England STS-12 (formerly Endura 12), recommends a sheave:rope diameter ratio of 8:1. That would mean for a 1/8" rope, one could get away with a sheave of only 1" in a pulley. Somehow that just doesn't seem like a good idea in this application though, but I don't know. So I'm asking.

If this were the case then, one could simply order these items off Amazon and be done with it:
https://www.amazon.com/Smittybilt-27...s=snatch+block
https://www.amazon.com/dp/B01I25Z5F4...v_ov_lig_dp_it


8 inches is okay, but there are other reverse pulley considerations. If you want the wheel to track the glider climb and drift, as in the old Cotswold system, a larger diameter is probably better. It was an effective 50" radius using using small rollers to reduce any stored energy in the system, which was an issue with the Essex GC system. With UHMWPE rope, you want to eliminate both stored energy and the ability for slack rope to tuck into any gaps or result in loops that might impact on the ground or equipment. Larger rope types might help with some of this, but there are always compromises of performance and price. UV resistence, abrasive resistence, fatigue (as a result of loading cycles), and ease of handling (including splicing) are all considerations.

This might be a suitable substitute for UHMWPE ropes for reverse pulley, http://www.novabraid.com/rope/oletec-12/ though they make no claims on abrasion resistance. 3/8" might be so heavy as to cause abrasive issues. This was true on the Cotswold system using solid wire. 10 gauge was heavy enough to cause excessive wear on the "memory loops" on the wire, so 13 gauge was found to give the best performance. Use of solid wire is not recommended at public use airports wherever you are because a large clear zone is needed in case of wire breaks. Many of these new ropes have negligible stretch, thus no recoil issues. Solid wire and steel wire ropes have significant recoil hazards.

Frank Whiteley


WRT Cotswold 50" diameter.


50" diameter was for a solid steel wire. The 1:8 ratio would put the sheave diameter for a 1/8" rope at 1".
  #8  
Old January 3rd 19, 05:28 AM posted to rec.aviation.soaring
Frank Whiteley
external usenet poster
 
Posts: 2,099
Default Wanting to start a new glider club

On Wednesday, January 2, 2019 at 9:49:18 PM UTC-7, John Foster wrote:
On Wednesday, January 2, 2019 at 4:18:44 PM UTC-7, Frank Whiteley wrote:
On Wednesday, January 2, 2019 at 2:39:13 AM UTC-7, Frank Whiteley wrote:
On Wednesday, January 2, 2019 at 12:59:47 AM UTC-7, John Foster wrote:
On Tuesday, January 1, 2019 at 8:13:46 AM UTC-7, Martin Gregorie wrote:
On Mon, 31 Dec 2018 19:21:45 -0800, WB wrote:

There is nothing new under the sun when it comes to ground launching,
auto tow, winch, whatever. It's pretty much all been tried. Derek Piggot
wrote a book that is a great resource for learning about ground launch
in it's many forms. Unfortunately, it appears to be out of print.

  #9  
Old January 2nd 19, 09:11 AM posted to rec.aviation.soaring
Frank Whiteley
external usenet poster
 
Posts: 2,099
Default Wanting to start a new glider club

On Tuesday, January 1, 2019 at 8:13:46 AM UTC-7, Martin Gregorie wrote:
On Mon, 31 Dec 2018 19:21:45 -0800, WB wrote:

There is nothing new under the sun when it comes to ground launching,
auto tow, winch, whatever. It's pretty much all been tried. Derek Piggot
wrote a book that is a great resource for learning about ground launch
in it's many forms. Unfortunately, it appears to be out of print.

ITYM "Gliding - A handbook on Soaring Flight"

Edition 7, which I have (blue cover showing a DG-800B with its motor
out), has two chapters on ground launching and is currently on offer from
Amazon for $3.60. His books may be out of print, but you can easily find
copies. Amazon even has a Derek Piggott author page.


--
Martin | martin at
Gregorie | gregorie dot org


Derek's insights on ground launching are very good. There are a number of variables that need some additional consideration. Here in Colorado summers, we can have density altitudes approaching 10,000ft at 5500MSL field elevation, which affect performance of both winches and gliders and auto tows, if used. The OP's location is at 3000MSL with slightly lower expected seasonal temperatures.

I'm not aware of any operations that have used direct or reverse-pulleys with UHMWPE ropes. 30 plus years ago, the old Enstone GC attempted to use a pulley with Parafil and the results were not successful. Could have been a design issue. Parafil worked a treat for auto tow and could be retrieved quickly for the next launch. I'm not certain UHMWPE ropes would work in those cases, however, Amsteel II is a sheathed rope, so might work in a similar role.

Direct pulley and auto tow is often done without a drogue chute so the rope will drop without much drift. A chute could result in considerable drift without any control. A drogue chute on a reverse pulley allows the end of the rope to be landed next to the pulley and it will be set up for the next launch. A rope break is the only real problem. The OP's airport has runway lights, which in my opinion makes direct pulley and auto tow not viable. There is a second airport option, very close to the mountains, which might allow easy access to ridge soaring. If the wind is enough for ridge flight, it would also maybe help with the launch heights to reach for the lift and/or return to the airport. A reverse pulley would allow for operations from both sites, though there is the problem of different run lengths. John, what was that second airport?

Frank Whiteley

  #10  
Old January 2nd 19, 07:01 PM posted to rec.aviation.soaring
John Foster
external usenet poster
 
Posts: 354
Default Wanting to start a new glider club

On Wednesday, January 2, 2019 at 2:11:23 AM UTC-7, Frank Whiteley wrote:
On Tuesday, January 1, 2019 at 8:13:46 AM UTC-7, Martin Gregorie wrote:
On Mon, 31 Dec 2018 19:21:45 -0800, WB wrote:

There is nothing new under the sun when it comes to ground launching,
auto tow, winch, whatever. It's pretty much all been tried. Derek Piggot
wrote a book that is a great resource for learning about ground launch
in it's many forms. Unfortunately, it appears to be out of print.

ITYM "Gliding - A handbook on Soaring Flight"

Edition 7, which I have (blue cover showing a DG-800B with its motor
out), has two chapters on ground launching and is currently on offer from
Amazon for $3.60. His books may be out of print, but you can easily find
copies. Amazon even has a Derek Piggott author page.


--
Martin | martin at
Gregorie | gregorie dot org


Derek's insights on ground launching are very good. There are a number of variables that need some additional consideration. Here in Colorado summers, we can have density altitudes approaching 10,000ft at 5500MSL field elevation, which affect performance of both winches and gliders and auto tows, if used. The OP's location is at 3000MSL with slightly lower expected seasonal temperatures.

I'm not aware of any operations that have used direct or reverse-pulleys with UHMWPE ropes. 30 plus years ago, the old Enstone GC attempted to use a pulley with Parafil and the results were not successful. Could have been a design issue. Parafil worked a treat for auto tow and could be retrieved quickly for the next launch. I'm not certain UHMWPE ropes would work in those cases, however, Amsteel II is a sheathed rope, so might work in a similar role.

Direct pulley and auto tow is often done without a drogue chute so the rope will drop without much drift. A chute could result in considerable drift without any control. A drogue chute on a reverse pulley allows the end of the rope to be landed next to the pulley and it will be set up for the next launch. A rope break is the only real problem. The OP's airport has runway lights, which in my opinion makes direct pulley and auto tow not viable. There is a second airport option, very close to the mountains, which might allow easy access to ridge soaring. If the wind is enough for ridge flight, it would also maybe help with the launch heights to reach for the lift and/or return to the airport. A reverse pulley would allow for operations from both sites, though there is the problem of different run lengths. John, what was that second airport?

Frank Whiteley


The second airport is St Ignatius (52S). Elevation is about the same at about 3K ft. Runway is only 2600 ft though. It also has runway lights.

Again, the purpose of this thread is to look at (cheap) options to get a club STARTED in a rural area in a low population density state. There is not a lot of money around here. Obviously there are better ways to launch gliders, but it costs more, and I'm looking for ways to make this affordable, at least until we can achieve critical mass to make this club self-sustaining. At that point we could start looking at options to improve launch equipment. At this point we don't even have sufficient interest to generate enough capital to buy a two-seater glider, even one that is only $6000. There is interest, but not enough people to put money on the table yet. That's my challenge.
 




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