[RocketsNW] Parachute protection options

[dave woodard]

just go for a scale v2 landimg

--- On Fri, 11/14/08, kmcgoffin at worldaccessnet.com <kmcgoffin at worldaccessnet.com> wrote:

From: kmcgoffin at worldaccessnet.com <kmcgoffin at worldaccessnet.com>
Subject: Re: [RocketsNW] Parachute protection options
To: "Greg Deputy" <greg at blastzone.com>
Cc: rockets at rocketsnw.com
Date: Friday, November 14, 2008, 12:07 AM

Which is my feeling about pistons in rockets.  Tube materials that
swell/shrink with changes in temperature or humidity, slightly
out-of-round tubes, BP crud sticking to critical surfaces, cumulative
invisible but significant damage during landings...you'd better be
prepared to put in significant TLC to ensure proper functioning.

Pistons have their place in rocket recovery systems, but not in little
stuff 'n shoot fun-time rockets.
+McG+


> No doubt!  When you're talking about thousands of an inch for the
diameter
> of your piston, etc, its time to move on!
>
> -----Original Message-----
> From: rockets-bounces at rocketsnw.com [mailto:rockets-bounces at rocketsnw.com]
> On Behalf Of Bloom, Steven E
> Sent: Wednesday, November 12, 2008 1:28 PM
> To: Simpsonclark at aol.com; foreveryoung at inlandnet.com;
> kmcgoffin at worldaccessnet.com; Mfreptiles at aol.com
> Cc: rockets at rocketsnw.com
> Subject: Re: [RocketsNW] Parachute protection options
>
> or just wrap it in a burrito and toss in a handfull of dog barf.....
>
> :>)
>
> ________________________________
>
> From: Simpsonclark at aol.com [mailto:Simpsonclark at aol.com]
> Sent: Wednesday, November 12, 2008 9:36 AM
> To: Bloom, Steven E; foreveryoung at inlandnet.com;
> kmcgoffin at worldaccessnet.com; Mfreptiles at aol.com
> Cc: rockets at rocketsnw.com
> Subject: Re: [RocketsNW] Parachute protection options
>
>
> Graphite or glass composite pistons molded to match the inside of the
> glass body tube and then sealed with an O-ring in a simple sawn and
> filed groove can maintain 3 or 4 thousandths radial clearance, which is
> the recommended clearance.  That won't grab a rolled and
shroud-wrapped
> chute. The pistons can be molded by draping a cylinder with wet glass
> and pushing it to the bottom of a release-coated short piece of body
> tube and then setting it on a release-coated surface, ideally a convexly
> curved surface.  I have no standard preference respecting the
> installation orientation.  Lube the body tube with silicone grease.
> -Robert
>
> In a message dated 11/11/2008 12:35:04 P.M. Pacific Daylight Time,
> steven.e.bloom at boeing.com writes:
>
> 	You have cardboard pistons in your vehicle and compressor?!?!???
>
> 	Seriously :>),  The tolerances, surface smoothness, and lack of
> a rag (parachute) laying on top of the piston make comparison.....
> incomparable.
>
> 	steve
>
> 	-----Original Message-----
> 	From: Bryan Young [mailto:foreveryoung at inlandnet.com]
> 	Sent: Tuesday, November 11, 2008 11:26 AM
> 	To: kmcgoffin at worldaccessnet.com; Mfreptiles at aol.com
> 	Cc: rockets at rocketsnw.com
> 	Subject: Re: [RocketsNW] Parachute protection options
>
> 	It sounds like I need to learn how pistons are designed -- they
> seem to work well enough in my air compressor and vehicles. Are there
> any references that contain piston design that I could look into?
> 	-B
>
> 	-----Original Message-----
> 	From: rockets-bounces at rocketsnw.com
> [mailto:rockets-bounces at rocketsnw.com]
> 	On Behalf Of kmcgoffin at worldaccessnet.com
> 	Sent: Tuesday, November 11, 2008 2:19 AM
> 	To: Mfreptiles at aol.com
> 	Cc: rockets at rocketsnw.com
> 	Subject: Re: [RocketsNW] Parachute protection options
>
> 	Yes, it seems to be a delicate balance between having enough
> clearance to avoid binding, and having too much clearance that can catch
> the parachute or allow the piston to tilt enough to 'catch'. 
It's a
> rather fault-intolerant design. Best suited for rockets made with high
> grade materials and given lots of TLC before launch.  Not good for
> "stuff another motor in and fly 'er" type hobby rockets.
>
> 	That may have something to do with why I was never a regular
> user of piston ejection.  :-)
> 	+McG+
>
>
> 	> In a message dated 11/9/2008 2:50:17 A.M. Pacific Standard
> Time,
> 	> kmcgoffin at worldaccessnet.com writes:
> 	> (I always wondered why the parachute didn't bind between the
> piston
> 	> and body tube.)  I dunno.
> 	>
> 	> It sometimes does, especially with overzealous sanding of the
> piston
> 	> skirt.  The larger the airframe diameter, the more likely this
> can
> 	> happen since tolerances are usually greater.
> 	>
> 	> Mike F.
> 	> AOL Search: Your one stop for directions, recipes and all
> other
> 	> Holiday needs.
> 	>
>
> http://pr.atwola.com/promoclk/100000075x1212792382x1200798498/aol?redir=
> http
>
> ://searchblog.aol.com/2008/11/04/happy-holidays-from-aol-search/?ncid=em
> lcnt
> 	ussear00000001
> 	> Search Now
> 	> .
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> 	>
>
>
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-------------- next part --------------
just go for a scale v2 landimg
--- On
Fri, 11/14/08, kmcgoffin at worldaccessnet.com
<kmcgoffin at worldaccessnet.com>
wrote:
From: kmcgoffin at worldaccessnet.com <kmcgoffin at worldaccessnet.com>
Subject: Re: [RocketsNW] Parachute protection options
To: "Greg Deputy" <greg at blastzone.com>
Cc: rockets at rocketsnw.com
Date: Friday, November 14, 2008, 12:07 AM
Which is my feeling about pistons in rockets. Tube materials that swell/shrink with changes in temperature or humidity, slightly out-of-round tubes, BP crud sticking to critical surfaces, cumulative invisible but significant damage during landings...you'd better be prepared to put in significant TLC to ensure proper functioning. Pistons have their place in rocket recovery systems, but not in little stuff 'n shoot fun-time rockets. +McG+ > No doubt! When you're talking about thousands of an inch for the diameter > of your piston, etc, its time to move on! > > -----Original Message----- > From: rockets-bounces at rocketsnw.com [mailto:rockets-bounces at rocketsnw.com] > On Behalf Of Bloom, Steven E > Sent: Wednesday, November 12, 2008 1:28 PM > To: Simpsonclark at aol.com; foreveryoung at inlandnet.com; > kmcgoffin at worldaccessnet.com; Mfreptiles at aol.com > Cc: rockets at rocketsnw.com > Subject: Re: [RocketsNW] Parachute protection options > > or just wrap it in a burrito and toss in a handfull of dog barf..... > > :>) > > ________________________________ > > From: Simpsonclark at aol.com [mailto:Simpsonclark at aol.com] > Sent: Wednesday, November 12, 2008 9:36 AM > To: Bloom, Steven E; foreveryoung at inlandnet.com; > kmcgoffin at worldaccessnet.com; Mfreptiles at aol.com > Cc: rockets at rocketsnw.com > Subject: Re: [RocketsNW] Parachute protection options > > > Graphite or glass composite pistons molded to match the inside of the > glass body tube and then sealed with an O-ring in a simple sawn and > filed groove can maintain 3 or 4 thousandths radial clearance, which is > the recommended clearance. That won't grab a rolled and shroud-wrapped > chute. The pistons can be molded by draping a cylinder with wet glass > and pushing it to the bottom of a release-coated short piece of body > tube and then setting it on a release-coated surface, ideally a convexly > curved surface. I have no standard preference respecting the > installation orientation. Lube the body tube with silicone grease. > -Robert > > In a message dated 11/11/2008 12:35:04 P.M. Pacific Daylight Time, > steven.e.bloom at boeing.com writes: > > You have cardboard pistons in your vehicle and compressor?!?!??? > > Seriously :>), The tolerances, surface smoothness, and lack of > a rag (parachute) laying on top of the piston make comparison..... > incomparable. > > steve > > -----Original Message----- > From: Bryan Young [mailto:foreveryoung at inlandnet.com] > Sent: Tuesday, November 11, 2008 11:26 AM > To: kmcgoffin at worldaccessnet.com; Mfreptiles at aol.com > Cc: rockets at rocketsnw.com > Subject: Re: [RocketsNW] Parachute protection options > > It sounds like I need to learn how pistons are designed -- they > seem to work well enough in my air compressor and vehicles. Are there > any references that contain piston design that I could look into? > -B > > -----Original Message----- > From: rockets-bounces at rocketsnw.com > [mailto:rockets-bounces at rocketsnw.com] > On Behalf Of kmcgoffin at worldaccessnet.com > Sent: Tuesday, November 11, 2008 2:19 AM > To: Mfreptiles at aol.com > Cc: rockets at rocketsnw.com > Subject: Re: [RocketsNW] Parachute protection options > > Yes, it seems to be a delicate balance between having enough > clearance to avoid binding, and having too much clearance that can catch > the parachute or allow the piston to tilt enough to 'catch'. It's a > rather fault-intolerant design. Best suited for rockets made with high > grade materials and given lots of TLC before launch. Not good for > "stuff another motor in and fly 'er" type hobby rockets. > > That may have something to do with why I was never a regular > user of piston ejection. :-) > +McG+ > > > > In a message dated 11/9/2008 2:50:17 A.M. Pacific Standard > Time, > > kmcgoffin at worldaccessnet.com writes: > > (I always wondered why the parachute didn't bind between the > piston > > and body tube.) I dunno. > > > > It sometimes does, especially with overzealous sanding of the > piston > > skirt. The larger the airframe diameter, the more likely this > can > > happen since tolerances are usually greater. > > > > Mike F. > > AOL Search: Your one stop for directions, recipes and all > other > > Holiday needs. > > > > http://pr.atwola.com/promoclk/100000075x1212792382x1200798498/aol?redir= > http > > ://searchblog.aol.com/2008/11/04/happy-holidays-from-aol-search/?ncid=em > lcnt > ussear00000001 > > Search Now > > . > > _______________________________________________ > > Rockets mailing list > > Rockets at rocketsnw.com > > http://mx1.blastzone.com/mailman/listinfo/rockets > > > > > _______________________________________________ > Rockets mailing list > Rockets at rocketsnw.com > http://mx1.blastzone.com/mailman/listinfo/rockets > > > _______________________________________________ > Rockets mailing list > Rockets at rocketsnw.com > http://mx1.blastzone.com/mailman/listinfo/rockets > > _______________________________________________ > Rockets mailing list > Rockets at rocketsnw.com > http://mx1.blastzone.com/mailman/listinfo/rockets > > > > > > ________________________________ > > Get the Moviefone Toolbar > <http://pr.atwola.com/promoclk/100000075x1212774565x1200812037/aol?redir > =http://toolbar.aol.com/moviefone/download.html?ncid=emlcntusdown0000000 > 1> . Showtimes, theaters, movie news & more! > > _______________________________________________ > Rockets mailing list > Rockets at rocketsnw.com > http://mx1.blastzone.com/mailman/listinfo/rockets > > _______________________________________________ Rockets mailing list Rockets at rocketsnw.com http://mx1.blastzone.com/mailman/listinfo/rockets