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  #21  
Old 10-19-2010, 11:36 PM
Les Les is offline
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Quote:
Originally Posted by Doug Sams

Long shock cords: Whoever came up with the foul notion that making the shock cord longer solves the problem of high speed deployment needs to take a high school course in physics. If your rocket is plunging toward the earth at 400mph, I don't care if the shock cord is 300 feet long, when the rocket gets to the end of the cord, there's gonna be one heckuva a jerk on the airframe, the suspension lines and the recovery harness. You can quote me on that.


.


I have found the typical Estes cord to be too short with the nose cone snapping back and denting against the tube. Having a longer cord does help with that (especially with the newer Estes "shot gun" ejection charges). Plus, with a longer cord there is more time for the air friction from the separated tube/nose cone to slow things down so the shock cord will not get as hard a yank.

But I will agree if the ejection is way to late or early so the rocket is going 400 mph , probably nothing will help.
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  #22  
Old 10-20-2010, 03:05 AM
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Baffles - I use them in my LMRs and MPRs. They speed up prep times and save 'chutes. Hardly ever used in anything smaller than BT-60, though.

Long shock cords - how long do you mean? My standard is 3x the length of the airframe. That works well for me.

Aeropack-style retainers - only on big expensive rockets, when there isn't much room for anything else. Or scale models, in situations where they will help maintain the scale appearance. Otherwise, I make my own retention mechanisms.

Tapered fins - just look cool. I only make mine that way very occasionally, though.

Clear coat - I completely agree with you.

Igniters - I have hardly ever had a problem with Estes igniters. I consider them to be very well-made and extremely reliable. I haven't had enough experience with "R2D2" igniters to form an opinion about them yet. But I have found out (the hard way) that my club's launch system is definitely not "Quest-friendly."

OK, now, here's one of mine - fiberglassing kits. Especially when they are accompanied by the firm belief that absolutely everything in rocketry is better if it is covered with a fabric woven from extremely fine fibers of alumino-borosilicate glass.
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  #23  
Old 10-20-2010, 03:24 AM
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Also: Level 1 high power certification - when it is attained by someone who got started in the hobby the day before yesterday.

And Level 2 certification - when it is granted to the same person a week later.
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  #24  
Old 10-20-2010, 07:53 AM
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Quote:
Originally Posted by Mark II

Long shock cords - how long do you mean? My standard is 3x the length of the airframe. That works well for me.

.

I agree on your shock cord length. Perhaps I should have elaborated when I said I prefer a shock cord that's WAY too long, and instead stated WAY longer than a SUPPLIED shock cord usually is.

Speaking of ignitors, I seem to remember a VERY reliable ignitor form the early 70's that (I believe) was called the Cox Sure-Shot ignitor. I believe it was some kind of 3 part affair with a tiny brown stick that you would wrap nichrome wire around, bend the stick in half, insert into the engine, and then secure with a supplied red or orange sticky dot. Does anyone else remember these?
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  #25  
Old 10-20-2010, 08:03 AM
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Quote:
Originally Posted by Bill
The Estes tube marking guide. I like the two discs for the different size tubes, but the provided straightedge is somewhat flexible and gives me inconsistent results. I use aluminum angle instead for marking lines on a tube.


Bill

Exactly! The disks are a great tool--the angled straightedge is NOT. Like you, I use an aluminum angle--but I always insert a BT coupler into each end of the tube first before marking so the line doesn't go parabolic.

Now, if only Quest had a set of marking disks for their BT's........
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  #26  
Old 10-20-2010, 08:41 AM
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Chas Russell Chas Russell is offline
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"Cox Sure-Shot ignitor."

Actually, they were Centuri Sure-shots which were invented by Irv Wait and sold by his company Rocket Development Corporation as "Ignit-rite" igniters. Centuri brought Irv in to continue his work on the Enerjet composite motors and changed the igniter's name.

Sure-shots were one of the best products ever. I flew nine cluster flights and only had one motor not fire as the Sure-shot burned, but was pulled out by the clips. The igniter stick was the prefered fire source for the flashbulb ignitors. John Langford (Aurora Flight Sciences) popularized the flashbulb system. Most of my remaining Sure-shot sticks will not burn correctly and mostly smolder. They have been hauled around the country during military service.

Cox did have their own unique igniters that were plugged into a specific holder on their launch pad. It had a pyrogen head that made it look like a match.

Dougie - decaff !!!

Chas
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  #27  
Old 10-20-2010, 08:48 AM
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All of the items listed by Doug as useless and overrated I find to be of GREAT use.
ALL my rockets use baffles wherever possible; when constructed properly they provide 100% protection of the chute.
Anything I have BT55 size or larger has a baffle.

Clearcoat EVERYTHING; not doing so is pure laziness or being a cheapskate.

Engine retainers- why not ? It makes things easier.

Anybody that does not understand the benefits of a longer shock cord needs to take a remedial physics course BADLY ! Most of my rockets use a shock cord about 3 times the length as supplied. Never get "estes dents" to the cone or tube either.

I taper the vast majority of all my 3FNC and 4FNC rockets for the extra performance- it takes little extra time and the performance gain is free.

I have ZERO problem with someone Certing level 1 and 2 in the same day that has never before launched a rocket; then again I don't think the cert process should exist AT ALL for flying high-power. If up to me it would be a free-for-all whereever, whenever, devoid of ANY regulation AT ALL !
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  #28  
Old 10-20-2010, 08:49 AM
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Quote:
Originally Posted by Chas Russell
"Cox Sure-Shot ignitor."

Actually, they were Centuri Sure-shots which were invented by Irv Wait and sold by his company Rocket Development Corporation as "Ignit-rite" igniters. Centuri brought Irv in to continue his work on the Enerjet composite motors and changed the igniter's name.

Sure-shots were one of the best products ever. I flew nine cluster flights and only had one motor not fire as the Sure-shot burned, but was pulled out by the clips. The igniter stick was the prefered fire source for the flashbulb ignitors. John Langford (Aurora Flight Sciences) popularized the flashbulb system. Most of my remaining Sure-shot sticks will not burn correctly and mostly smolder. They have been hauled around the country during military service.

Cox did have their own unique igniters that were plugged into a specific holder on their launch pad. It had a pyrogen head that made it look like a match.

Dougie - decaff !!!

Chas

Centuri Sure-Shot igniters. Thanks for the correction. No, I NEVER had one fail either.
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  #29  
Old 10-20-2010, 08:53 AM
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Cox igniters were some sort of patented little plugs called "safety" igniters; they were of little resemblance to Centuri sure-shots.
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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL
, if you have to ask what is "NORMAL" , you probably aren't !

Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !
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  #30  
Old 10-20-2010, 08:54 AM
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Chas Russell Chas Russell is offline
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The early Sure-shots used a press-on adhesive dot to hold the wick and nichrome in the nozzle. Later versions had a special tape piece that had tabs that allowed a more positive retnesion, but they were a real pain to build. I just masking taped the assembly in.

Chas
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