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From: [e-mail] (Buzz McDermott)
Subject: Frequently Asked Questions - Part 4 of 5
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Rec.Models.Rockets FAQ (Frequently Asked Questions): Part 4 of 5

Last Modified: 20 Nov 1992

*** PART 4: PAYLOADS

[Note: This part of the FAQ is maintained by Jack Hagerty ([e-mail])
Any additions or corrections should be sent to that address]


Introduction

    Flying sport rockets is fun. Flying competition rockets
    can be exciting in the heat of battle. Scale models (my favorite) can
    be as much of a challenge to research and build as they are to fly.
    But if you want to do something "real" with your rocket, you've got
    to fly a payload. This is also a good response to the perpetual
    question from the the great unwashed masses "so, what's it do?"

I've  organized this section into the following topics (suggestions for
    expansion into other topics gladly accepted):

    4.1 Camera Payloads
       4.1.1 Commercial Cameras
       4.1.2 Homebrew cameras
       4.1.3 Video
    4.2 Data Gathering Payloads
       4.2.1 Transmitter
       4.2.2 Data logging
       4.2.3 Sample collection
    4.3 Bio-payloads
    4.4 Novelty Payloads
       4.4.1 Contest payloads
       4.4.2 Ejecting payloads

4.1 Camera Payloads - Cameras are the most often flown payloads (after eggs
   and bugs :-) because they hit us where we live. No other payload lets us
   see the flight from our rocket's point of view. The intensity of interest
   in camera payloads can be seen by how early they were flown: Goddard flew
   them, the VfR (the German rocket society which gave Von Braun his start)
   flew them and, of course, dozens of post war sounding rockets carried
   camera payloads.

   Some of the products and techniques that have been tried and/or are still
   available are:

4.1.1 Commercial Cameras (chronological order):

Camroc - The first purpose-designed rocket camera. Designed by Estes and
   sold from 1965 to 1974. A marvel of simplicity, it was patterned after
   several homebrew cameras of the early '60s (see 4.1.2). It was simply a
   cylindrical body that held the film topped by a hemispherical nose that
   was flattened off to accept the optical window which the forward facing
   lens looked through. One shot per flight on "Astropan 400" (Kodak Tri-X)
   cut into a 1 1/2" dia. round negative. Easy to process at home. The film
   had to be push processed to 1200 ASA (officially, though most home
   developers went to 1600). Extremely valuable on the collector market.
   [Note: Don't write me asking how much your old Camroc's worth. Bob
   Sanford ([e-mail]) tracks those sorts of things - JH]

   Greg Smith ([e-mail]) describes some of the various hacks
   of the Camroc: "At one time there were quite a few homebrew modifications to
   the Camroc floating around. Most popular was substituting a 3-element glass
   lens from Edmund Scientific for the standard plastic lens; it gave much
   sharper and better color-corrected results. I have also seen a wide-angle
   variation with yet another Edmund lens that required cutting the forward body
   section of the Camroc down to a much shorter length. As someone pointed out
   at the time, the Camroc lens was a short telephoto relative to its film
   format. It doesn't make sense to send a rocket up as high as possible and
   then use a telephoto lens to get a SMALLER angle of view; it's a wide angle
   you really want, so you can get more in the picture from a lower, easier-to-
   aim flight with a smaller motor and less risk of losing the camera. Several
   people flew color slide film in the Camroc, but high-speed color films were
   pretty terrible at the time; the ASA 1600 print films available today would
   probably work very well in it."

Cineroc - Estes' second foray into camera payloads, the Cineroc was *much*
   more sophisticated than the Camroc. This was a full bore 8mm movie camera
   crammed into a package not much bigger than it's predecessor (although more
   aerodynamic). Introduced with much fanfare in 1969, it lasted only 5 years
   before its plug was pulled in 1974. The lens looked aft via a hooded mirror
   and it shot ~15 sec worth of flight time at 2X speed (30 sec projection
   time). At least that's what the spec says. In reality, most Cinerocs ran in
   the 18 - 20 fps range which is more-or-less normal speed. The film was a
   Kodak ASA 160 instrumentation film on a polyester base which was probably
   adopted because it was the only daylight-balanced Super 8 film available.
   The Cineroc used a custom film cartridge meaning that you either used the
   Estes processing service or went to a custom lab.  It could be developed
   at home using a Kodak E-4 developing kit, but this was *much* more trouble
   than most modelers would want to go.

   The official reason for its early demise, still lamented to this day, was
   that the small electric motor it used went out of production. However,
   in a conversation with Mike Dorffler (the designer) he revealed that the
   product was killed by a combination of events that occurred over a very
   short (2 month) period in early '74: the motor went out of production,
   Eveready stopped making the tiny "N" batteries, Kodak changed the formula
   of the film which couldn't be accommodated by the custom lab doing their
   processing and, the coup de' gras, a technician dropped the mold for
   making the custom lens.

   Many Cinerocs are still flown today nearly 20 years later. The size "N"
   alkaline batteries, much better than the original carbon-zinc ones that
   Estes supplied, are widely available now; and the new film stock (which
   is available off the shelf, not special order like the one Estes originally
   chose) is sharper and less grainy than the old stuff. Both of these
   actually make for easier and better Cineroc results today than when it was
   first introduced.  You do still need a custom film lab to deal with the
   nonstandard lengths of 8mm film, however.

Astrocam 110 - Another Estes product and something of a combination of the
   previous two. Reverting to the still format, the Astrocam was designed
   around a stock 110 cartridge. It took multiple shots per roll of 400
   speed color print film, but still only one frame per flight. The lens
   looked out through a hooded mirror (like the Cineroc) but this time looking
   forward (like the Camroc). Image quality was marginal due to the plastic
   lens and small format, but the film can be developed anywhere (although the
   prints are reversed). A very long lived product, it lasted from it's 1979
   introduction until early 1992, and literally thousands are still in use.
   A late rumor has it that Estes may bring it back in early 1993 due to
   public demand.

Other commercial camera payloads - California Consumer Aeronautics (San
   Diego, CA) sells a very small Super 8 movie camera suitable for HPR
   payloads, but it's not a ready-to-fly system. Cotriss Technology (San
   Jose, CA) specializes in rocket photography, and sells a complete HPR
   still camera system (including rocket) called the Observer.

   Note: I have not had dealings with either of these companies. Proceed
   at your own risk. Address and phone info in the "address" section.

4.1.2 Homebrew cameras and techniques:

Still Cameras

Historic - The earliest hobby type rocket with a camera was reported on
   in the March 1983 issue of _The Model Rocketeer_ (the predecessor to
   AmSpam) in the article "King George VI's Rocketeers." As Chris Tavares
   ([e-mail]) reports: "A school group in Scotland formed what
   is possibly the first model rocketry club [in the late '40s - JH]. Of
   course, there were no commercial model rocket motors available, but they
   used pennywhistle fireworks motors. The group's advisor designed and flew
   a camera-bearing rocket with which he took several photos of a nearby
   loch. The motors were pre-manufactured by professionals, used once, and
   thrown away.  The airframes were designed by the modelers, and made out
   of paper and light woods.  It's as valid an implementation of 'model
   rocketry' as what goes on today in eastern Europe."

   According to Stine (Handbook, 2nd Edition) the first true "model rocket"
   (in the NAR Safety Code defined sense) camera payload was flown by Lewis
   Dewart in 1961. Lewis simply strapped a tiny Japanese novelty camera to
   the side of a model.  The shutter was tripped by the nose cone separating.
   Shortly after that, Dennis Guill upped the sophistication by taking the
   shutter and lens of a similar camera and mounting it on a plastic tube
   that just fit inside a rocket body tube with the lens facing forward. It
   used sheet film cut into a circular negative and the cocked shutter was
   released by a lanyard (a shoelace!) at ejection (sound familiar?). It was
   an aerodynamic nightmare, but Estes saw enough promise to develop it into
   the Camroc.

Current - The present wealth of lightweight, autowind cameras on the market
   makes it relatively easy to design a sequence camera that shoots a whole
   roll of film on a flight. A crude-but-effective setup was developed by
   Peter Alway and described in Vol 3, No 2 issue of _T-5_ (the HUVARS
   newsletter). Peter took a cheap autowind 110 camera and came up with a
   simple arrangement of a motor, a stick and some bits of wire to repeatedly
   trip the shutter.  This setup was flown on an "E" motor.

   A similar, but more sophisticated, system was detailed in the March/April
   1992 issue of AmSpam. Steve Roberson designed his system around HPR to give
   him power to boost a high quality 35mm camera to significant altitudes. He
   took a relatively expensive Olympus autowind camera and triggered it with a
   very solid (but simple) cam-and-lever mechanism. A nice feature of this
   camera is that it automatically rewinds the film into the can at the end of
   the roll which would enhance its survivalbility in the event of a crash. A
   tribute to Steve's design and flying skills is that the camera and rocket
   were retired, intact, after 22 High Power flights (H & I motors).

   A recent variation on this theme was flown by Bob (I forget the last name)
   at NARAM 34 last August. He had found a brand of compact 35mm camera which
   comes equipped with "sequence" mode (i.e. it keeps shooting at ~1 fps as
   long as the shutter is pressed). Additionally, the shutter is electronic so
   that all it takes is a contact closure to activate (no more moving parts).
   Bob had switches at several places on the rocket to trigger the camera
   either as it cleared the launch rod, or at payload separation. He also used
   a recovery harness to keep the lens pointed at the ground during descent.

   Another very involved HPR camera project by Ray Dunakin was covered in
   four parts (and counting) by _The Tripolitan_ over the first 4 issues
   of 1992, but is too involved to even summarize here.

   Several r.m.r readers have announced projects to convert cheap film-box
   cameras into payloads, but none have posted their results yet. One
   ambitious soul (name please!) is even attempting to add film advance/shutter
   trip mechanism to make a sequence system. We'll keep you posted.

Movie Cameras - The first model rocket movie camera was flown by Charles & Paul
   Hans and Don Scott in 1962. A heavy spring-wound Bosley 8mm camera was
   crammed into a payload section and lofted by an early "F" motor. The story
   is still recounted by Stine in the most current edition of the Handbook.
   (Note: Paul Hans currently works for ISP/Aerotech).

   Due to the greater difficulty of adapting a movie camera, and relatively
   easy access of Cinerocs, not too many homebrew movie cameras have been
   flown, compared to still cameras. I'd be happy to include documented
   examples here, if you send me the references.

4.1.3 Video

   This is a brand new area with much work going on, but only
   a few successes to report. There are two ways of returning video from
   a rocket: record and transmit.

Record - Following the lead of film cameras, attempts have been made to
   fly stripped camcorders (using HPR, obviously!) to record the flight
   while on board. Video tape recording, however, is a very delicate
   technology and the accelerations encountered in rocket flight jiggle,
   dislodge and otherwise move the tape all over the recording heads in
   a disruptive manner. To date, I have only one report of someone making
   this work. Stu Barrett ([e-mail]) reports: "At a recent San
   Antonio Prefecture launch, Randy Reimers (an expert video technician) had
   a Sony camcorder with the camera separated from the transport via a wire
   harness. He had the transport installed so that the tape was vertical to
   the ground.  That seemed to keep the tape on the tape heads.  He did say
   that under the acceleration of a K550, there was a slight herringbone
   pattern on the tape during the boost that he attributes to vibrating tape
   due to high G's.  The J415 did not have this phenomena."

   [Moderator's note: Both Stu and I agree that this sounds sideways. One
   would think that the tape transport should be positioned so the tape runs
   flat (WRT the acceleration) over the heads. What can I say? This guy is
   the expert and he got results - JH]

Transmit - Transmitted video has had more frequent success, but complicates the
   process by adding a whole new technology. While the components that ride
   in the rocket have no moving parts, you must add transmitters and antennae
   to your vehicle, plus receivers and recorders to your GSE.  License-less
   video transmitting is allowed by the FCC, but the power limitations raise
   more problems. Omni directional transmit antennae are easy to track, but
   the signal strength drops off *fast* (inverse square law).  Directional
   antennas concentrate the signal, but require that you track the rocket, or
   hope that it doesn't go too far off course!

   A good, but somewhat superficial, article on transmitted video appeared
   in the July '92 issue of _73 Amateur Radio Today._ Being a radio hobby
   magazine, it concentrated on that aspect (and assumed you know a bit
   about it) and left the rocket parts at sort of the gee-whiz level. The
   system transmitted with 6 Watts (the developer was a licensed ham) and
   returned a good, clear picture to an altitude of 1,200 ft. The rocket
   was an HPR (no details given) but this was just the checkout vehicle for
   the transmitter hardware which is slated to go into an LOX/Kerosene amateur
   rocket with a design altitude of 200,000 ft.

   Additionally, the HUVARS group is working on this technology, plus the
   _Tripolitan_  is promising an article on the subject RSN :-)

Commercial - Hans Schneider (Plainsboro, NJ) runs a rather crude ad in the
   _Tripolitan_ offering an HPR based B&W video broadcast system (including
   rocket) for a hefty $385.

4.2 Data Gathering Payloads - The payloads covered in this section come
   the closest to the "real" kind in purpose. The whole reason for launching
   professional rockets is to return information from a place that is difficult,
   dangerous or even impossible to visit first hand.

   The earliest data gathering payloads in model rockets were pretty crude. The
   only way of returning the data was to send the recording media up with it.
   Thus we had peak-reading accelerometers consisting of a spring mounted weight
   scratching a line on some graph paper, peak-reading dial or mercury tube
   thermometers, peak-reading manometers and...well, you get the idea :-)

   It wasn't long before advances in electronics, namely small and cheap
   transistors, made it possible to launch radio transmitters to return data
   from the whole flight (not just the peaks) to the ground for later analysis.
   Now only the sensors had to fly while the recording and analysis equipment
   could stay on the ground (again, much like the "real" thing).

   The astounding recent advances in electronics and computer science have
   brought us full circle. The absolutely unforseeable (at the beginning of
   the hobby) degree of miniaturization in electronics has once again allowed
   us to launch the recording media, but now it's in the form of a full blown
   computer system small enough for even modest model rockets to loft. Rather
   than getting one crude data point per flight, we can get hundreds or even
   thousands while doing the analysis right on board!

4.2.1 Transmitter

Historic -  According to the Stine Handbook, the first purpose-designed model
   rocket telemetry transmitter was designed by Bill Robson and John Roe.
   The unit broadcast on the Citizen's Band and was first publically flown
   at NARAM 2 in 1960.  It was a simple multivibrator that put out a continuous
   tone which could be modulated by a sensor, but what to do with the wavering
   tone it sent back was left as an exercise for the reader :-) Stine still
   includes the schematic for this device in the current edition of the
   Handbook, although he finally admits to it being "a very old design."

Foxmitter - Using the same basic encoding principle (and still broadcasting on
   the Citizen's Band), Richard Fox designed the "Foxmitter" which was described
   in the May thru December '69 issues of the old _Model Rocketry_ magazine. An
   improved version, the "Foxmitter-2" was detailed in the June '70 thru Jan '71
   issues of that same journal. The thing that made it an advance over the Roe/
   Robson design (and the reason it took so many issues to describe) is that the
   Foxmitter used a basic transmitter module into which multiple sensor modules
   could be plugged (one at a time).  The sensors covered included a basic tone
   module (for tracking purposes), temperature, humidity, acceleration and even
   a microphone!

   In some related articles in the Aug/Sept '70 MRM, Alan Stolzenberg used the
   Foxmitter as the basis for his "Bio-1" design which involved a very clever
   respiration sensor to monitor the flight subject from order Rodentia (see
   Section 4.3 below). This was, of course, before launching mammals and other
   higher orders fell into disfavor in the hobby.

Transroc - In a case of deja-vu all over again, Estes took a well developed
   homebrew design, in this case the Foxmitter, and turned it into a commercial
   product.  This time, they also borrowed a page from the Heathkit notebook
   and let the customer do the assembly (it was also available pre-assembled).
   Like the Foxmitter, the Transroc used sensor modules to let you mix 'n match
   the parameters you wanted to measure.  Available were the basic beeping tone
   module (aka "Rocketfinder" mode), a temperature module, spin rate module and
   a microphone module.

   The Transroc announced the beginning of the Estes "Rocketronics" line with
   its introduction in 1971. It also quietly marked the end when it disappeared
   with the 1977 catalog. Note: The current "Transroc II" sold by Estes is NOT
   an RF transmitter! It is an audio beeper designed to help you find your model
   after landing. It can be heard by the "naked ear" several hundred feet, but
   that can be extended by using the ground unit which is a highly directional
   microphone with a narrow pass filter on an amplifier.

Adept Rocketry in Broomfield, CO mentions "Telemetry Transmitters/Receivers"
   in their magazine ads, but this is all I have on the product.

4.2.2 Data Logging

Historic - The rise of the microprocessor coincided almost perfectly with
   my hiatus from the hobby. If anyone out there has documented examples
   of the first micro-p to be flown in a model or HPR, send it to me and
   I'll include it here.

Homebrew - The October 1990 issue of _Radio-Electronics_ magazine had a very
   long and detailed article by John Fleischer on an altimeter payload based
   on a solid state pressure sensor. The system consists of three parts: an
   analog board with the sensor and signal conditioning, a CPU board and a
   display module. The latter stays on the ground and can read out the data
   in either selected peaks (shades of the beginning!) or do a 1/4 speed "slo-
   mo" playback of the entire flight. The article contains schematics, parts
   lists and even board masks for etching your own.

Commercial - Along with all other aspects of the computer industry, small
   "garage" type companies dominate the computer rocket payload industry.
   Following are a few data logging payloads that I have information on.
   As usual, caveat emptor:

   Flight Control Systems of Camp Hill, PA sells a very sophisticated
   system called the FP1 (Flight Pack One) Data Logger. This consists
   of a complete computer system on a 1.6" wide x 11" long board into
   which the sensor board plugs. The system not only logs data from the
   sensors, but comes with a development system so that you can write your
   own programs to start/stop data logging based on time or other flight
   events (e.g. staging). The ground support software (all PC based) is
   quite extensive consisting of archiving software (to connect the FP1
   to your PC) and data analysis software to crunch numbers once it's
   there. The standard sensor board has altitude/ velocity and temperature
   sensors on it, but they also provide a prototype board for designing
   your own. The sensor board can be remote mounted from the CPU board.
   Price for the FP1, sensor board and software is a rather substantial $300.

   Some other companies producing data logger payloads (on which I have no info
   outside of their ads in the magazines) are:

   Transolve Corp, Cleveland, OH - Sells the "A2 Micro Altimeter" which sounds
   like a production version of the _Radio-Electronics_ system described above.

   Adept Rocketry, Broomfield, CO - Has quite a line of electronic products
   including peak reading & continuous altimeters, and on-board computers.

   Finally, we have from the r.m.r address list the following entries of which I
   know even less:

   Langley Autosystems in Sunnyvale, CA  is listed with "Datastick on-board
   computer"

   High Technology Flight in Ypsilanti, MI sells "Electronic Payloads".


4.2.3 Sample collection

   This final type of data collection is practiced
   only rarely by professionals. True, some satellites are designed to be
   returned for study (the LDEF is a notable example), but outside of Earth
   orbit, the only unmanned "sample return" missions have been some moon rocks
   brought back by the Soviet "Luna" series.

   I have only one documented example of sample collection by model rocket.
   In the anthology "Advanced Model Rocketry" complied by Michael Banks,
   there is an entry by Eric Nelson describing a system used to collect
   atmospheric pollen and spore samples. It used an Estes Omega to loft a
   sampler consisting of a hollow nose with a clever arrangement of springs
   and marbles acting as check valves.

4.3 Bio-payloads

   The official position on biological payloads can be
   summed up in one word: "Don't." The perfectly reasonable rationale
   here is that this is an educational hobby and you really aren't going
   to learn anything new by torturing your pet gerbil or lizard to see
   if he'll survive (and if he doesn't, how will you know what killed him?
   Launch shock? Burnout deceleration? Recovery deployment? Impact?)

   With that disclaimer out of the way, though, we must admit that there
   are other reasons for launching living things, as any 10 year old can
   tell you.  If you have to do it, though, try to stay outside your own
   Phylum :-) No one's going to get too upset if you launch a few plant
   leaves (Some HPR guys even use lettuce as recovery wadding) and few
   are going to risk the hypocrisy of objecting to a gastropod-naut after
   killing hundreds of them with snail pellets the week before.

   Be careful if you start venturing into the Chordates, though. While
   I'm sure there have been more rocket riders from Class Insecta that
   all other bio-payloads combined, stay out of Vertibrata. Anything with
   a backbone is a definite no-no.

4.4 Novelty Payloads

   This section is the catch-all for everything else
   your rocket might carry outside of its own structure. If you can think
   of a broader category for some of these things, let me know and I'll
   consider re-arranging it.

4.4.1 Contest Payloads.

NAR standard payload - It wasn't long after the founders of the hobby had
   the propulsion and airframe parts of the system sorted out that they
   wanted to do "something else" during contests. Thus was the idea of
   lofting a "dead" weight born. The first NAR standard payload was a slug
   of lead 3/4" in diameter weighing 1 oz. Later, this was changed to being
   a cylinder filled with sand. The official description (from the Pink book)
   reads: "The standard NAR model rocket payload is a non-metallic cylinder
   filled with fine sand, with a mass of no less than 28 grams [1 oz]. This
   cylinder shall be 19.1mm [3/4"] in diameter and 70mm in length."

Tripoli water payload - As with everything else in HPR, their standard contest
   payload is larger than life :-)  They figured that if the standard NAR
   payload is one ounce, then the standard Tripoli contest payload should
   be one pound.  Rather than using lead or sand, though, they upped the
   difficulty by using water. Also, there is no standard container for the
   water, just a requirement that the airframe be 2.25" diameter at some
   point and be able to hold 16 fl oz of water. The payload compartment is
   weighed both before and after flight to make sure that you didn't leave
   any "vapor trails" during flight. One added wrinkle is that everyone must
   use the same 36" chute, one of which is provided to each contestant.

Eggs - According to Stine, the idea of flying raw eggs is attributed to
   Captain David Barr of the USAF Academy in 1962. Originally, this was used
   as a qualification test to see if you had the skills to launch a biological
   payload with a good chance of getting it back alive. It quickly took on a
   life of its own, so to speak, as a competition. The "official" raw egg is
   described in the Pink Book as: "a raw, USDA Large hen's egg with a mass of
   no less than 57 grams and no more than 63 grams, and measuring no more than
   45mm in diameter."

4.4.2 Ejecting payloads

   Generally speaking, the hobby discourages ejecting
   things out of your rocket (other than the recovery system, of course!)
   so as to not appeal too much to the "warhead" mentality that we run into
   all too often. However, there is great crowd pleasing effect to be had
   in dropping a bunch of colorful "ejecta" for everyone to chase.

   Versions of this type of rocket have been around for some time.  Plans
   for a "concept" rocket called "The Purple People Eater" by Ken Brown were
   published in the December, 1980 issue of _Model Rocketry_ magazine. The
   model drops various types of streamers and "flutterers" at ejection. A
   larger version of this model was flown by Chris Tavares off of NARAM 34's
   sport range last August.

   Expanding on the concept, the "ZIA Spacemodelers Sport Design Notebook"
   compiled by Tom Beach contains a design by John Pratt called "Bombardment."
   Capitalizing on various novelty toys available on the market, this model
   carries three foam gliders (Guillow Co. "Delta Streak") as parasites and
   has a modified egg capsule crammed with all sorts of goodies. Included are
   three "Pooper Trooper" parachuting army figures, six "Re-entry Vehicles"
   made from strips of trash bag taped to rubber washers and a hand full of
   "Penetration Aids" (black confetti) thrown in for good measure.

   Once again Estes came along and formalized the idea with a production
   version they call "Bailout". This is nothing more than a wide diameter
   rocket with a body tube big enough to hold an action figure (e.g. GI Joe).
   The kit includes an extra parachute for the figure, but you have to supply
   Joe. Despite the appearance, the figure does *NOT* leave via the "hatch"
   on the side. That's just a decal. He ejects out the top with the regular
   recovery system. Reports on r.m.r of success with this model have been
   mixed, mostly because the recommended "B" motors are awfully wimpy to loft a
   100+ gram model (Joe usually prangs before his chute unfurls), and the
   recommended "C" motor is the "CATO-master" C5-3.

   Speaking of CATOs, Estes also has a model of the same name which sort of
   fits in this category. While it technically doesn't eject anything, it
   does break apart in the air and comes down in pieces.