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#11
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Parachute source for gliders and winches
My understanding, walking (let alone running) in heels is tough...no, never tried either.....
As to suitability of one drag chute vs. another, seems like a major factor is if you drag it on the ground and whether or not it is pavement/macadam and load on the tow cable/wire. |
#12
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Parachute source for gliders and winches
The simple response to that is:Â* Don't drag it on the ground.Â* When I
was driving a winch back in the 90s, the technique was to increase throttle sufficiently after the glider releases to keep the parachute inflated and drop the chute right in front of the winch. The driver had to have the skill to stop the drum before the chute got jammed in the rollers.Â* On days without cross winds, just carry enough power to keep the chute inflated until it lands. On 11/11/2018 1:54 PM, Charlie M. (UH & 002 owner/pilot) wrote: My understanding, walking (let alone running) in heels is tough...no, never tried either..... As to suitability of one drag chute vs. another, seems like a major factor is if you drag it on the ground and whether or not it is pavement/macadam and load on the tow cable/wire. -- Dan, 5J |
#13
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Parachute source for gliders and winches
On Saturday, November 10, 2018 at 8:27:50 PM UTC-7, AS wrote:
On Saturday, November 10, 2018 at 9:54:22 PM UTC-5, wrote: On Thursday, November 1, 2018 at 6:18:55 PM UTC-6, Martin Gregorie wrote: On Wed, 31 Oct 2018 09:06:05 -0700, JS wrote: Saw the ad in the AMA flyer for their Expo in Pomona. SSA Region 12 has a presence there. AMA Expo: https://amablog.modelaircraft.org/am...8/10/expowest- program-2018-web.pdf Fruity Chutes looks like a good source for chutes, including ballistic chutes. Anything from 12" diameter up. Jim https://fruitychutes.com/ The Fruity chutes I looked at would all be unlikely to survive their first winch launch: thie all emphasized light weight, which is exactly what you don't want for winching. The winch parachute is inline between cable and shock cord. The tension being carried through the 'chute keeps it closed during the 60-65 knot launch, when the 'underside' of the 'chute is facing the winch and the shock cord, connecting chute to glider, it attached to the top centre of its bell. If the launch didn't finish it off a light weight chute, then being dragged back to the winch after the launch would probably do the trick. That is why traditional winch chutes are made of heavy duty canvas with typically four shrouds made of 50-75mm heavy duty webbing sewn onto the shock cord attachment at the centre of the chute. Current manufacture chutes often use plastic fabric, but its just as thick as the canvas it replaces. -- Martin | martin at Gregorie | gregorie dot org What Martin said.. Try this for a (relatively) cheap 'chute. Bite the bullet and buy one Tost small winch 'chute and take it to your local rigger and ask how much to make a replica. There's a good chance that will be much less than what you paid for the 1st 'chute. We have been using this type of military surplus chute for years now and they hold up very well. The trick is to 'fly' the chute reasonably close to the winch and then drop it but not drag it over the ground. https://www.ebay.com/itm/NEW-UNISSUE...-1:rk:140:pf:0 Unfortunately, they have become harder and harder to find. Fortunately, I bought a few at a surplus store in TX, when they still had them. ;-) Uli 'AS' The orange chutes have become rare to non-existent, but work very well if you can source them. The similar option looks reasonable. Might have to order one to see if it's useful. Frank Whiteley |
#14
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Parachute source for gliders and winches
On Sun, 11 Nov 2018 14:10:03 -0700, Dan Marotta wrote:
The simple response to that is:Â* Don't drag it on the ground.Â* When I was driving a winch back in the 90s, the technique was to increase throttle sufficiently after the glider releases to keep the parachute inflated and drop the chute right in front of the winch. The driver had to have the skill to stop the drum before the chute got jammed in the rollers.Â* On days without cross winds, just carry enough power to keep the chute inflated until it lands. Spot on for normal operation, but there is one unavoidable difference if you're using Spectra rope. On steel cable, you do the last launch of the day, suck the cable in, pack the winch up and tow it back to its roost and everything is fine. But if you do the same with Spectra rope, it will destroy the winch drums because tightly wound Spectra is likely to crush the drum in overnight cold, so after the last launch both cables are pulled out again. The winch then pulls them in slowly enough to avoid inflating the chute. This leaves the ropes loose enough on the drums to prevent crushing problems, but has also dragged the 'chutes along the ground for the length of your airfield. -- Martin | martin at Gregorie | gregorie dot org |
#15
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Parachute source for gliders and winches
I hesitate (not really) to ask how you learned what the Spectra could do.
I've only launched and driven with steel cable or plain rope with auto tow. On 11/11/2018 4:26 PM, Martin Gregorie wrote: On Sun, 11 Nov 2018 14:10:03 -0700, Dan Marotta wrote: The simple response to that is:Â* Don't drag it on the ground.Â* When I was driving a winch back in the 90s, the technique was to increase throttle sufficiently after the glider releases to keep the parachute inflated and drop the chute right in front of the winch. The driver had to have the skill to stop the drum before the chute got jammed in the rollers.Â* On days without cross winds, just carry enough power to keep the chute inflated until it lands. Spot on for normal operation, but there is one unavoidable difference if you're using Spectra rope. On steel cable, you do the last launch of the day, suck the cable in, pack the winch up and tow it back to its roost and everything is fine. But if you do the same with Spectra rope, it will destroy the winch drums because tightly wound Spectra is likely to crush the drum in overnight cold, so after the last launch both cables are pulled out again. The winch then pulls them in slowly enough to avoid inflating the chute. This leaves the ropes loose enough on the drums to prevent crushing problems, but has also dragged the 'chutes along the ground for the length of your airfield. -- Dan, 5J |
#16
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Parachute source for gliders and winches
On Sunday, November 11, 2018 at 6:26:47 PM UTC-5, Martin Gregorie wrote:
On Sun, 11 Nov 2018 14:10:03 -0700, Dan Marotta wrote: The simple response to that is:Â* Don't drag it on the ground.Â* When I was driving a winch back in the 90s, the technique was to increase throttle sufficiently after the glider releases to keep the parachute inflated and drop the chute right in front of the winch. The driver had to have the skill to stop the drum before the chute got jammed in the rollers.Â* On days without cross winds, just carry enough power to keep the chute inflated until it lands. Spot on for normal operation, but there is one unavoidable difference if you're using Spectra rope. On steel cable, you do the last launch of the day, suck the cable in, pack the winch up and tow it back to its roost and everything is fine. But if you do the same with Spectra rope, it will destroy the winch drums because tightly wound Spectra is likely to crush the drum in overnight cold, so after the last launch both cables are pulled out again. The winch then pulls them in slowly enough to avoid inflating the chute. This leaves the ropes loose enough on the drums to prevent crushing problems, but has also dragged the 'chutes along the ground for the length of your airfield. -- Martin | martin at Gregorie | gregorie dot org Martin, steel cables do have the tendency to crush drums when not wound up after the last launch loosely, particularly if you were winching during a warm/hot summer day and experience a drop in temperature over night. Spectra is less affected by temperature swings but it is so tightly packed on the drum after the launch that it can crush a drum if left in that condition. We always pay out the line after the last launch and haul it it in at moderate speed, i.e. 1st gear at idle. Dragging the chute several thousand feet over any kind of surface is just plain nuts! No wonder you are wearing it out in no time. Tie an old tire to the end, if you desire some resistance. Uli 'AS' |
#17
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Parachute source for gliders and winches
Did Bill and Martin just agree on a winch related topic?!
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#18
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Parachute source for gliders and winches
On Sun, 11 Nov 2018 15:54:13 -0800, AS wrote:
steel cables do have the tendency to crush drums when not wound up after the last launch loosely, particularly if you were winching during a warm/hot summer day and experience a drop in temperature over night. When we used steel cable we didn't do anything special - just put the winch, a Supacat, away with the cables wound from the last launches. Maybe the Supacat drums were stronger than I realised: certainly the whole winch looked to have been made with surplus battleship parts from its air-cooled V8 diesel engine onward. When we replaced the Supacat with a Skylaunch (and later added a Tost that had been upgraded by Skylaunch) we switched to Spectra and the pull out and rewind loosely after the last launch. Our field is mown grass which doesn't obviously harm the heavy duty canvas and webbing parachutes we use. What I said initially applies only to those lightweight Fruity chutes. -- Martin | martin at Gregorie | gregorie dot org |
#19
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Parachute source for gliders and winches
On Sun, 11 Nov 2018 16:44:19 -0700, Dan Marotta wrote:
I hesitate (not really) to ask how you learned what the Spectra could do. There was feedback in S&G from early adopters about it and, when we bought the Skylaunch I'm fairly certain it was in the operating manual. Disclaimer: I regularly serve as part the airfield's normal operating crew, but at the launchpoint and driving the cable tow-out truck. I had some winch training on the Supercat, but don't drive the Skylaunch. I've only launched and driven with steel cable or plain rope with auto tow. I never seen auto tow used - its very much a dieing art over here due to the availability of good modern winches. Our longest cable run is just on 1km (3270 ft) long. Typical calm weather launches get to 1400ft but I've had 2600-2700 ft on windy days with a decent velocity gradient in both ASK-21 and SZD Juniors. -- Martin | martin at Gregorie | gregorie dot org |
#20
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Parachute source for gliders and winches
It's true that Spectra (Dyneema) has a thermal coefficient of expansion at 180 - 200 M/(MxK) - roughly 20X that for steel and 10X that for aluminum. Leaving it wound tightly on a cold night probably has caused drums to fail.
However, there's no need to drag the 'chute - that's what old tires are for.. Keep a couple handy with an eye-bolt through the tread to attach the rope to. Pulling a tire across the whole airfield can be done quickly at the end of the day leaving the Spectra wound loosely enough not to cause problems. On Sunday, November 11, 2018 at 4:26:47 PM UTC-7, Martin Gregorie wrote: On Sun, 11 Nov 2018 14:10:03 -0700, Dan Marotta wrote: The simple response to that is:Â* Don't drag it on the ground.Â* When I was driving a winch back in the 90s, the technique was to increase throttle sufficiently after the glider releases to keep the parachute inflated and drop the chute right in front of the winch. The driver had to have the skill to stop the drum before the chute got jammed in the rollers.Â* On days without cross winds, just carry enough power to keep the chute inflated until it lands. Spot on for normal operation, but there is one unavoidable difference if you're using Spectra rope. On steel cable, you do the last launch of the day, suck the cable in, pack the winch up and tow it back to its roost and everything is fine. But if you do the same with Spectra rope, it will destroy the winch drums because tightly wound Spectra is likely to crush the drum in overnight cold, so after the last launch both cables are pulled out again. The winch then pulls them in slowly enough to avoid inflating the chute. This leaves the ropes loose enough on the drums to prevent crushing problems, but has also dragged the 'chutes along the ground for the length of your airfield. -- Martin | martin at Gregorie | gregorie dot org |
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