[RocketsNW] Parachute protection options

[Brad Wright]

Sigh.... must we do this every year??  Pistons work just as well as any other recovery system PROPERLY applied.  I've flown numerous piston designs and numerous non-piston designs with EQUAL success and failure.  Like any design proper USAGE and attention to DETAIL is needed.  More failures in our hobby are due to user error than anything else.  Anyone who doesn't admit that is fooling themselves.

Some simple piston rules:

1) preferably use the same material for the airframe and piston - The Wildman and Hawk Mountain Beast as examples

2) if using different materials understand the thermal and friction dynamics and PLAN for them

3) one correction to the below comment, a piston system requires LESS BP than a non-piston design - and yes this is from real world experience


Both piston and non and viable and I use both but you need to understand the design and failure modes of everything you use.

b

-----Original Message-----
From: rockets-bounces at rocketsnw.com [mailto:rockets-bounces at rocketsnw.com] On Behalf Of Robert Krausert
Sent: Wednesday, November 26, 2008 4:08 PM
To: Dennis Winningstad; 'Bill Munds'; steven.e.bloom at boeing.com; 'Steve C'; simpsonclark at aol.com; foreveryoung at inlandnet.com; kmcgoffin at worldaccessnet.com; 'Mike Fisher'
Cc: rockets at rocketsnw.com
Subject: Re: [RocketsNW] Parachute protection options

Ok, here is the question/comment. I'd invite anyone from PML to build one of
there $200+ birds with a piston and fly it with us all watching. They of
course shouls have a flawless flight, right?

Or do the piston if you wish. Try to make sure you add enough BP to get the
piston out. I think some do not realize how much is needed, because the
piston under vacuum and pressure at the same time, but all in the wrong
place. If you normally use 10 grains for a 3" airframe, one with a piston
needs more. The equation I use is [normal grains] times [500]. So if you
normally use 10 grains without, you'll need 5000 grains with a piston. Hot
or cold. Plastic or paper. This will get the piston out.

LOL. Just kidding.
Cheers,
Robert
----- Original Message -----
From: "Dennis Winningstad" <winningstad at comcast.net>
To: "'Bill Munds'" <appusher at q.com>; <steven.e.bloom at boeing.com>; "'Steve
C'" <steve-c at ix.netcom.com>; <simpsonclark at aol.com>;
<foreveryoung at inlandnet.com>; <kmcgoffin at worldaccessnet.com>; "'Mike
Fisher'" <mfreptiles at aol.com>
Cc: <rockets at rocketsnw.com>
Sent: Wednesday, November 26, 2008 1:27 AM
Subject: Re: [RocketsNW] Parachute protection options


> My Lvl 1 cert flt (the successful one!) was w/PML Ariel utilizing a
> piston.
>
>
>
> Dennis S Winningstad
>
> 503-781-3529
>
> "Why not go to war just for oil? We need oil. What do Hollywood
> celebrities
> imagine fuels their private jets? How do they think their cocaine is
> delivered to them?"
>
> Ann Coulter
>
>  _____
>
> From: Bill Munds [mailto:appusher at q.com]
> Sent: Tuesday, November 25, 2008 5:21 PM
> To: winningstad at comcast.net; steven.e.bloom at boeing.com; Steve C;
> simpsonclark at aol.com; foreveryoung at inlandnet.com;
> kmcgoffin at worldaccessnet.com; Mike Fisher
> Cc: rockets at rocketsnw.com
> Subject: RE: [RocketsNW] Parachute protection options
>
>
>
> you could always go with redundancy and place a charge under the parachute
> to ensure it really comes out.
>
>
>
>
>
>
>
> <http://im.live.com/Messenger/IM/Home/?source=EML_WLHM_GreaterGood>
> i'mEMAILING FOR THE GREATER GOOD
> Join me
>
>
>
>> From: winningstad at comcast.net
>> To: steven.e.bloom at boeing.com; steve-c at ix.netcom.com;
> Simpsonclark at aol.com; foreveryoung at inlandnet.com;
> kmcgoffin at worldaccessnet.com; Mfreptiles at aol.com
>> Date: Mon, 17 Nov 2008 18:17:19 -0800
>> CC: rockets at rocketsnw.com
>> Subject: Re: [RocketsNW] Parachute protection options
>>
>> ...piston recovery uses less BP.
>>
>> ...piston recovery is, like, way-cool.
>>
>> ...I like complicated systems.
>>
>> ...risk is SO invigorating!
>>
>> Dennis S Winningstad
>>
>> 503-781-3529
>>
>> "Why not go to war just for oil? We need oil. What do Hollywood
> celebrities
>> imagine fuels their private jets? How do they think their cocaine is
>> delivered to them?"
>>
>> Ann Coulter
>>
>>
>> -----Original Message-----
>> From: rockets-bounces at rocketsnw.com
>> [mailto:rockets-bounces at rocketsnw.com]
>> On Behalf Of Bloom, Steven E
>> Sent: Monday, November 17, 2008 6:33 AM
>> To: Steve Cutonilli; 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
>>
>> While I don't use pistons, I could still possibly offer some alternate
>> creative solutions. First, could you finish the following sentence?
>>
>> This airframe requires a piston recovery system because...
>>
>> steve
>>
>> -----Original Message-----
>> From: Steve Cutonilli [mailto:steve-c at ix.netcom.com]
>> Sent: Sunday, November 16, 2008 9:32 PM
>> To: Bloom, Steven E; 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
>>
>> You sir are a better man than I - can you describe component specs and
>> space allowances? The original thread on pistons pertained to 38mm -
>> for all other formats you are probably correct. /Steve
>>
>> -----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
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>> > Search Now
>> > .
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