Personal reconsideration

Personal reconsideration

Post by Jack » Sat, 03 Aug 1996 04:00:00




Quote:

>What kind of camera are you using?  I'm using a Vivitar Opus 35, which is
>very cheap, compact, and easy to modify but has a slow shutter and a
>plastic lens.  I'm considering upgrading to something else like the Fuji
>Discovery 90 (I think I got the name right) which has a 1/600 sec. shutter
>speed.  Does Cotriss still sell first-surface mirrors, or is there a
>better source?  

I don't know the camera yet.  Requirements:

must fit in a 3" payload

self-winding

Relatively inexpensive (this IS an experiment!)

Jack Wiker

 
 
 

Personal reconsideration

Post by Rick Taylo » Sat, 03 Aug 1996 04:00:00


Quote:


> > So what rocket are you planning to fly next?

> Rick, I plan on making an appearance at the COSMOS launch of Tripoli
> Atlanta in September.  I still haven't decided if I will launch the 16
> ft. Terrier Sandhawk again, or if I will refly the Adrenaline Rush
> project, a 5.54" two stage that stages 3 I357's to 3 I211's.  Pictures of
> both rockets are located at: http://www.concentric.net/~ddmobley

> Construction plans call for the completion of a fairly large 8.75" to 6"
> PML-based two stage as well as a 2/5 scale Black Brant VB or VC built
> with 11.41" PML parts.  On the smaller size, I am conjuring up a 2.56" to
> 3" boosted Aerobee.

> How about you?

Looks like my next launch will be either Open Spot Landing at NARAM, or other
model rocket 'practice launches' with my kids before we go.

That aside, the one I'm looking forward to the most is a 6' 2.56" scratch built
with 29mm mount, piston ejection.  It flew fine on G80-4, then an F50 blew the
forward closure, burning out the motor tube and more; now it's rebuilt with spliced
motor and body tubes.  One of these days I'll want to try this on an H, but the
next flight will be another G80-4T.

I hope to build a 38 mm 2.56" 8' rocket one of these days -- I have the parts
and have the chute completed.

 
 
 

Personal reconsideration

Post by Darrell D. Moble » Sat, 03 Aug 1996 04:00:00


Quote:

> That aside, the one I'm looking forward to the most is a 6' 2.56" scratch built
> with 29mm mount, piston ejection.  It flew fine on G80-4, then an F50 blew the
> forward closure, burning out the motor tube and more; now it's rebuilt with spliced
> motor and body tubes.  One of these days I'll want to try this on an H, but the
> next flight will be another G80-4T.

> I hope to build a 38 mm 2.56" 8' rocket one of these days -- I have the parts
> and have the chute completed.

They both sounds great!  Keep us posted on the outcomes...
 
 
 

Personal reconsideration

Post by Larry Basket » Sat, 03 Aug 1996 04:00:00


Quote:

> I don't know the camera yet.  Requirements:
> must fit in a 3" payload
> self-winding
> Relatively inexpensive (this IS an experiment!)

Here's a more detailed look at the best 35mm camera candidates I've found:

Vivatar Opus 35 (older version is Pocket 35)
Disadvantages:
-1/150 sec. max shutter speed
-plastic lens
Advantages:
-very cheap
-relatively easy to modify
-fits inside a 2.6" tube (minimum)
-lightweight (~6 oz. fully loaded)
Cost:  $35 most places, $30 is a good deal

Fuji Discovery 90 (not as much info because I haven't bought one)
Disadvantages:
-large viewfinder makes it a little bulkier
Advantages:
-1/600 sec. max shutter speed
-glass lens
Cost:  $90 most places, $80 is an okay deal

Can anyone elaborate on or add to this list?  I'd like to set a price cap
at $120 for the sake of affordablilty.  The ideal camera would (obviously)
have all of the above advantages and none of the disadvantages.

The only hard part is wiring a timer.  I lost the circuit diagram for
mine, or else I'd offer it.  The method I used includes a 555 chip driving
a relay that shorts the shutter button contacts every couple of seconds.
The components don't cost all that much.

I have an old Cotriss catalog that lists a camera pre-wired with a timer
for $125; it may or may not still be available.  

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
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            / \
           |   |   Larry Baskett
           |   |

           |   |   http://www-leland.stanford.edu/~lbaskett/
           |   |
           |   |   NAR #60166, LUNAR #151
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=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

 
 
 

Personal reconsideration

Post by Dave Redel » Mon, 05 Aug 1996 04:00:00


Quote:

> Does Cotriss still sell first-surface mirrors, or is there a
> better source?

I bought a couple from Edmund Scientific. They are 51x51mm.
Presumably the optimal aspect ratio would be more like 1x1.9
instead of 1x1 (assuming that the camera is mounted sideways
and the mirror is at 45 degrees).

They also have a 38x38mm size, which would give less drag but
would need to be mounted closer to the lens. I haven't gotten
around to computing exactly how close the lens and mirror have
to be, but it seems like it shouldn't be too hard to figure out.

Prices are : 38mm $4.25
             51mm $4.75

Edmund Scientific 609-547-8880

Dave Redell

 
 
 

Personal reconsideration

Post by wolfb » Wed, 07 Aug 1996 04:00:00


Quote:


>> Does Cotriss still sell first-surface mirrors, or is there a
>> better source?

What is a first-surface mirror and how does it differ from other kinds
of mirrors?
 
 
 

Personal reconsideration

Post by Bill Nels » Wed, 07 Aug 1996 04:00:00


: >> Does Cotriss still sell first-surface mirrors, or is there a
: >> better source?

: What is a first-surface mirror and how does it differ from other kinds
: of mirrors?

If you look closely at a standard mirror, like the one in your bathroom,
you will see two reflections. The strongest will be off the back surface,
from the coating/glass interface. There will also be a weak one off the
front surface of the mirror.  There are actually a number of others, but
are very hard to see.

A "front surface" mirror is aptly named, as it has a shiny metal coating
on the front surface of the mirror. Thus, there is only one reflection,
as the light does not penetrate the mirror - at least, not to a significant
extent.

You should be able to visualize the advantage of the resultant single image.

Bill

 
 
 

Personal reconsideration

Post by Jeff Vince » Wed, 07 Aug 1996 04:00:00


Quote:


>> Serendipity strijes here.  Just received a catalog from Red Arrow Hobbies,
>> 5095 Red Arrow Hwy., Stevensville, Mi. 49127 , Phone Fax (616) 429 8233.
>I too got the catalog. BTW, it clearly came off a mailing list of an
>organization of which I am no longer a member... :-)

   Don't jump to conclusions, Bob, I got one too (and I was *never* a
member of "an organization of which I was never a member of"... ;).  
I probably got it as main contact for ASTRE (NAR section).


Pick one or more: Model Rockets (competition-NERCB) / PCs (even Atari!) /
Papyrus ICR-ICR2-NCR / Who needs a life when you have multiple non-lives?

 
 
 

Personal reconsideration

Post by Joe Pfeiff » Wed, 07 Aug 1996 04:00:00




   >> Does Cotriss still sell first-surface mirrors, or is there a
   >> better source?

   What is a first-surface mirror and how does it differ from other kinds
   of mirrors?

With most mirrors, the reflecting material is behind the glass (or
plastic).  With a first-surface mirror, it's in front.  The advantage
is that a normal mirror gives you a slight reflection off the first
surface, a refraction at the glass/air interface, and then a
reflection off the reflecting material.  A first-surface mirror only
gives you the single reflection.  When you're looking at angles of 45
degrees, the difference becomes significant (you can see the double
reflection in your bathroom mirror, if you look for it).  The
advantage of a conventional mirror is that the reflecting surface is
protected by the glass, and in everyday use you won't notice the
double reflection.
--
Joseph J. Pfeiffer, Jr., Ph.D.       Phone:  (505) 646-1605
Assistant Professor                  FAX:    (505) 646-1002
Department of Computer Science       http://www.cs.nmsu.edu/~pfeiffer
New Mexico State University          
Las Cruces, NM 88003                

 
 
 

Personal reconsideration

Post by Steven C. Smit » Thu, 08 Aug 1996 04:00:00


Quote:


> >Date:  Wed, 31 Jul 1996 13:14:40 -0700

> >Newsgroups:    rec.models.rockets
> >Subject:       Re: Personal reconsideration


> >> I find this to make more sense than most postings....

> >> by anyone....

> >Thanks, Jack.  I hope you were able to detect the serious and humbling
> >nature of my post.  I am tired of the negative exchanges.

> >What are you working on to fly?

> Getting right to it, huh?  ;)

> Right now I have a camera payload that I'm designing for my two stage, parts
> ordered for a 3X Trident, and I'm resurrecting my 5 1/2" dia Jayhawk for
> Level II cert.  If anyone's interested, I would be more than happy to
> elaborate on these projects.

> Jack Wiker

Jack,

Is this the same Jayhawk that had the spectacular flight at MRFF '96?

Steve

 
 
 

Personal reconsideration

Post by Jack Wike » Thu, 08 Aug 1996 04:00:00


Quote:

>Date:       Wed, 07 Aug 1996 09:04:10 -0500

>Newsgroups: rec.models.rockets
>Subject:    Re: Personal reconsideration

>> ordered for a 3X Trident, and I'm resurrecting my 5 1/2" dia Jayhawk for
>> Level II cert.  If anyone's interested, I would be more than happy to
>> elaborate on these projects.

>> Jack Wiker

>Jack,

>Is this the same Jayhawk that had the spectacular flight at MRFF '96?

>Steve

Spectacularly.......short!!

Actually, it only cracked one winglet.
Jack Wiker  TRA#(real high)