[RocketsNW] Parachute protection options

Wed Nov 26 23:57:20 PST 2008

> Sigh.... must we do this every year??

Yes, yes, it's written in the immutable laws of the universe somewhere!

Tastes great..less filling...did too...did not...

Past and upcoming attractions:
   October: Perfect launch weather or too damn cold?
   November: To piston or not to piston.
   December: Parachutes--Z-fold or simple roll?
   January: Warming cold motors--armpit or crotch?
   February: Epoxy, CA, or white paste?
   March: Tagging EX propellant--pet hair DNA or nanoparticle isotopes?
   April: BP or Pyrodex?
   May: Bruno Hauptman--guilty or innocent? (Gotta have at least one
totally OT topic)
McG+

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
>>> ussear00000001
>>> > Search Now
>>> > .
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