Archive-name: rockets-faq/part5
Posting-Frequency: monthly
Last-modified: 10 October 1994
*** PART 5: Payloads
Any additions or corrections should be sent to that address]
Updates
-------------
October '94: Updated AstroCam section with "Sticky Shutter" discussion. Updated
"Adept" section with new products. Updated "Transolve" section with
review from recent "Sprocketry".
August '94: Added "Night Flying" section. Updated hombrew still camera section
based on NARAM 36 inputs.
June '94: Added reference to "Microbats" project. Added "Alternative Boosters"
to Astrocam section. Updated some camera references.
April '94: Re-wrote section headings into "Q&A" format, minor editing throught.
Split off "Guidance Systems" into separate (new) Part.
Renumbered to "Part 5" as part of FAQ reorg.
Added table of motor "theoretical performance" in Astrocam Section.
Jan '94: Minor addition to camera introduction
-------------
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 also
provides you with a good response to the perpetual question from the great
unwashed masses when they ask "so, what's it do?"
5.1 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. In fact, the
very first operational (as opposed to experimental) rocket system was Alfred
Maul's photoreconnaissance rocket built for the German Army which was used
from 1912 until airplanes became more reliable.
Some of the products and techniques that have been tried and/or are still
available are:
5.1.1 Can I just go out and buy a camera for my rocket? What cameras will work?
Some commercial camera products produced over the years:
5.1.1.1 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 5.1.2). 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
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."
5.1.1.2 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 projec-
tion 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.
Gary Rosenfield, now president of Aerotech/ISP, made a name for himself
by coming up with a significant hack on the Cineroc that both reduced its
diameter and increased the film capacity. As detailed (somewhat sketchily)
in the V 14, N 1 (July 1974) issue of the _Model Rocket News_, Gary took
the basic guts of the camera (lens/film gate/geneva transport plus motor
and batteries) and put them in a BT-55 tube with the mirror hood outside
as usual. He extended the tube fore and aft enough to hold 50' of film (a
full cassette worth) in random storage, i.e. no spools. The film simply ran
from one compartment, through the gate and into the other compartment.
While this made the system much more difficult to reload in the field, you
could now have the film developed anywhere, provided you bothered to
rewind it back into the standard cassette afterwards. The photo of "Wild
Man Rosenfield" that accompanies the article is probably suitable for
blackmail :-)
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.
Some Cinerocs are still flown today 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.
5.1.1.3 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 when, for reasons known only to themselves, Estes canceled
it. Public demand was great enough that they re-introduced an "improved"
version in early 1993. Said improvements consisted of a better lens for a
sharper image, a one stop increase in aperture (so it can use the much more
available 200 speed film) and pre-assembly of the lens and sprocket. Perhaps
the biggest improvement of all was that they dropped the price by $10 :-)
5.1.1.4 AstroCam building and flying tips - The AstroCam is the source of
continual threads on r.m.r. The following is a distillation of nearly half
a megabyte worth of AstroCam discussions I've archived:
GENERAL TIPS
* The film is quite grainy, hence a lot of people move on to 35mm cameras.
* Underexposure is a problem - the pictures are lousy if you launch in
anything other than bright sun. Of course, there's also the usual problem
of forgetting to open the safety shutter before launch.
* Overexposure is a problem several ways:
- The shutter cord can get tangled in the shroud lines, taking multiple
exposures or one long exposure.
- A hard impact can take another shot. At the least, landing impact will
close the safety shutter making you wonder if you forgot to open it
before launch.
- Problems with sun and heat on the pad make some folks drape it with
aluminum foil until final countdown.
- Adjustments on the pad are always a source of causing the shutter
to go off on the pad.
* Chris suggests advancing the film before take off and advancing it after
landing. Yes, it wastes film, but you tend to not use all the shots anyway.
I believe that Kodak only makes 24 shot rolls of ASA 400 110 size film.
SOME THOUGHTS ON FILM
Modern C-41 stocks have a 2-step under / 3-step over exposure latitude. The
material has so low a contrast that little information is lost; the effect
is primarily a density shift which can be removed during printing.
K-Mart 200 speed print film (which is made by 3M, and sold under many
different "house" brands) makes an acceptable medium. It's cheap, comes in
12 exposure rolls, and has enough latitude to give acceptable exposure.
STICKY SHUTTER PROBLEMS
Many r.m.r readers report sticking shutters in their AstroCams. This ranges
from a completly stuck shutter that binds so tightly that it won't move, to
a mildly draging shutter that causes motion bluring and overexposure.
During construction of the camera, it is essential to monitor the shutter
movement after every step. It seems that a camera too tightly constructed
binds the shutter. Even though the current release of the AstroCam have the
lens and part of the shutter pre-assembled, it is still possible to get the
assembly too tight. It is also important to use *liquid* plastic cement on
this assembly. The liquid allows you to dry fit the parts to their proper
place and apply the cement afterwards which wicks into place. The gel-type
cements commonly used with model building requires that the parts be dis-
assembled after the dry fit to apply the cement, and they might not go back
together exactly same way the second time. Also, the "strings" and "oozes"
from gel cement can more easily contaminate the shutter slide.
A less common, but well documented problem is the clearance between the
shutter string and the film cartridge. Check the knot that ties the shutter
string to the shutter. On some AstroCams it tends to rub on the bottom of
the film cartridge when the latter is fully seated causing the shutter to
hang up after release. A mildly dragging knot causes overexposure but in more
severe cases you get either a totally blank or totally saturated negative
depending on where the shutter stalls. Since this is the case with my own
(original release) AstroCam, I now routinely carve a flat into the bottom
of the cartridge with a hobby knife before installing.
ENGINE COMBOS
Given a well constructed AstroCam, a C6-7 will produce a good shot.
However, an Estes D12-7 will produce a horizon shot or blurry shot as it
is still in motion (this was reported in the Model Rocketeer about 10 years
ago). A little weight will cure this without negating the effect of the D
motor. I've also used AeroTech D21-10 or E25-10 can work well, though I
wonder if a 10 second delay tends to produce horizon shots with an E-powered
launch. Dan Wolman tried an F-based launch which resulted in a blurry image
(again, probably too short a delay), so he tried an F25-10 and lost it to
wind/thermals.
With C6-7 engines, I have found that vertical flights range from 550-650 ft
in altitude. For horizon shots with C6-5 engines, the altitude was a little
better (photo taken earlier in descent) maybe 600-700 feet.
Estes B6-4's give horizon shots
Quest B6-4's give sky shots
Estes B4-6's give ground shots from ~30' up (real heart stoppers!)
Estes B8-5's give reasonable ground shots
A B6-4 will work, but it's hit or miss whether you'll get a ground or
sky shot. D21-10's are superb, though expensive. A C6-5 will give you a
horizon shot (if you're lucky). The C6-7 is almost guaranteed to give
you a shot of the ground.
analysis to see what the differences actually were between the various
motors. He reports:
I simulated all of the plausable engine combinations for AstroCams and the
two matching boosters Estes offers [the standard "Delta II" which has an
18mm motor mount and the "Maniac" which uses the same size body tube but
a 24mm motor mount - JH]
All calculations were done at STP atmospheric conditions, and all engines
are standard Estes, with thrust curves from their data sheets.
The results are arranged in order of increasing altitude at ejection.
Entries in the "combo" column are booster/engine, with D for the Delta II
and M for the Maniac. The drop time from apogee (Tdrop) and ejection
velocity are the relevant parameters in determining if a combo gives a
vertical, horizon, or sky shot. Combinations marked with a * are ones
I've tried, combinations marked with a '+' have been reliably reported (in
Bank's book *Advanced Model Rocketry* or here in the FAQ).
Booster/ Apogee ej alt ej vel Tdrop Comments
Engine (ft) (ft) (mph) (sec)
------------------------------------------------------------------------
D/B8-5* 197 136 -41 2.0 almost always vertical shots
D/B6-4* 209 192 -22 1.0 mix of sky, horizon, & vertical
M/C6-5 377 222 -39 1.9 -CAUTION- 19 mph liftoff!
D/C6-7* 492 357 -57 3.0 always a vertical shot
D/C6-5+ 496 479 -22 1.0 similar to B6-4, but more
variation.
M/D12-7+ 699 633 -43 2.0 reportedly blurry, some horizons
M/D12-5+ 701 701 -0.7 0.0 Banks says gives horizon shots,
but probably a bad bet.
M/E15-8 1094 1016 -47 2.2
M/E15-6 1096 1095 -5 0.2
The key thing here seems to be the drop time. If it can drop for 2 or
more seconds, you get a vertical shot; in the 1 second range you get
horizon shots. It looks like the E15-8 will mostly give vertical shots,
but remember that there's a +/-15% variation in delay charge lengths, so
you'll probably get some horizon shots as well.
noted:
Only the B6 AstroCam changed enough to be worth even mentioning - 192 feet
instead of 209 feet.
This is ballpark back-of-the-silicon-envelope figuring [but] it's good to
see folks doing numbers.
---------
REVERSING THE CAMERA
The original article [on reversing the AstroCam] was "Retrospective Rocketry"
in a 1980(?) issue of Model Rocketeer. It's since been reprinted by Estes in
one of their Model Rocket Newses, which you should be able to get. It may
also be available from NARTS.
Speaking of the MRN, the V34 N1 issue (Spring, '94) contains a couple of
articles showing a total of four different designs for reversing the camera.
They are all in considerable hand-holding detail, in keeping with the MRN
editorial style :-)
[Moderator's Note: In his book _Advanced Model Rocketry_, Michael Banks
including a "stereo" version incorporating two cameras*** on either
side of a large body tube. This, IMHO, would not produce any stereo effect
at altitudes above 50' due to the minuscule baseline (the OD of the body),
but would double your chances of getting a shot. Additionally, Tom Beach
he flew at NARAM 34, a photo from which was published in the Sept/Oct '92
AmSpam - JH]
ALTERNATIVE BOOSTERS
The Delta II rocket that comes with the AstroCam (actually, the booster
is unnamed in the current release) is stable, durable and hardworking. It
does, however, limit you to a single 18mm motor which restricts your
altitude to about 600 ft if you're using black powder or about 1,000 ft
if using a composite (e.g. the Aerotec D21). As previously mentioned in
"ENGINE COMBOS" above, the Estes "Maniac" will fit the AstroCam which will
let you fly a single 24mm x 70mm motor and get up to 1,500 feet or so.
The reason you can't just plop the A/C onto just any Estes rocket is that
it was designed around an old Centuri body tube size (Series 13) which is
just a tad larger than the Estes BT-55 (1.30" dia vs 1.28" for the BT-55).
This tube is not generally available from Estes (it has no catalog number)
but is sometimes referred to as "BT-56" internally. BT-55 has been made to
work if you peel one layer from the inside of the tube, but it should be
re-enforced using CA or some other glue to prevent buckling.
It has been reported ("Section Soundings," April, '94 HPRM) that the FSI
tubing size RT-12 is a very close match to the Centuri Series 13 and that
the FSI "Echo" makes a nice two stage AstroCam lofter.
CLEANING THE CAMERA
There is one hint that I don't think has been mentioned: Bring a few Q-tips
to the launch field in your range box. Use them to clean the lens before
launch.
I believe a #1 Camel's hair brush is a better cleaning tool than a Q-tip
for the mirror. Since the Q-tip doesn't bend like the brush bristles do,
the surface pressures on that front-surfaced mirror can be quite high. I'm
not sure what material is used for the "cotton" tip (rayon?) but some
synthetic fibers can be very abrasive.
To prevent dust from collecting on the mirror, I store my AstroCam/Delta
horizontally from a string with half a paper clip at each end hooked into
the launch lugs. Some people bag the camera in a plastic produce bag.
GETTING THE PHOTOS PRINTED "RIGHT"
Find a 1 hr photo place that does 110 film then have the film processed
normally. This means, of course, that the images will be reversed. If any
of the flight (or ground photos for that matter) came out well, then hand
the negatives back to the service droid and ask him/her to make some
reprints with the negative flipped. The key is that you're talking to the
person who'll be pushing the buttons so you can watch them do it.
If there's no one else ahead of you in the processing queue, they can do
this while you wait (it only takes abt 5 minutes) and if they***it up,
you can refuse the print and they'll try again.
Those of you with the right equipment can scan an AstroCam photo into
your computer, then properly reverse it electronically if you have Adobe
Photoshop software.
======================================
5.1.1.5 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. Please see address section for
complete addresses of these companies. Note: CCA has announced that it is
dropping all of its rocketry products, but they should still be able to point
you in the correct direction regarding the camera.
5.1.2 I don't want to just buy a camera system, I'd rather design and build my
own. What's already been done and what's available for "homebrewers"?
5.1.2.1 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 _Sport
Rocketry_ mag) in the article "King George VI's Rocketeers." As Chris
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***ed shutter was
released by a lanyard (a shoelace!) at ejection (sound familiar?). It was
an aerodynamic nightmare, but Estes saw enough promise to develop the
concept 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 survivability 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). Some more
photos of/by Steve are in the March/April 1993 HPRM. The same issue has some
killer aerial photos by Steve Lubecki as part of the "Danville 8" article.
A follow-up article in the August, 1993 AmSpam details the next generation
of this project which increased the size and sophistication significantly.
A variation on this theme was introduced by Bob Hart at NARAM 34 in Las
Vegas which he brought out again to NARAM 36 in Houston. He uses a compact
35mm camera which comes equipped with "sequence" mode (i.e. it keeps shoot-
ing 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. Other cameras at NARAM 36 included Bob Alway
Hart's but somewhat different in execution. Going the simpler (read "crash
of his adaptaion of a Kodak Disk camera. Thanks to the miracle of 1 hr
photo development shops, we were all able to enjoy the shots that evening!
and model of 35mm camera that is easily adapted for flight: "My favorite
is a RICOH Shotmaster AF Super. It has an electric switch remote shutter
release and a 'continuous' program mode. You set this mode and the camera
shoots a whole roll of film when the shutter release is held down (or the
remote contacts are shorted). The camera fits in an LOC 3" tube and even
rewinds the film at the end of the roll."
A very involved HPR camera project was covered in five parts by HPRM over
the 5 issues of 1992, but is too involved to summarize here. Parts 1 and 2
were reprinted in the March/April and May/June 1993 issues, respectively, so
that folks buying it off the rack could catch up (HPRM didn't "go public"
until halfway through the series).
was a good example of cross pollenating between hobbies:
"In the June '94 issue of "Circuit Cellar INK," a projects oriented
electronics magazine, there is the article "Aero-Pix Aerial Photography
System" that would appear to have some promise for medium-high power rocket
use. It's a microcontroller based system & uses a better timing system than
the typical 555 chip. It also details the mods to the Canon Snappy LX, a
camera that has an electronicly switched shutter.
"The main modifications that are probably necessary for rocket use are to
the software. The system was designed to be used with a weather balloon,
and the sequence starts a minimum of one minute after release & a minimum
frequency of one minute. I imagine though that the microcontroller should
make the change to more suitable timing quite easy.
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.
5.1.2.2 Movie Cameras
Historic - 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).
Current - 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.
The amateur "AmSpace" project outlined in the April '94 issue of HPRM
contains an 8mm film camera to back up its live video downlink. This
will be carried to 80 KM (over 260,000 ft)!
California Consumer Aeronautics (San Diego, CA) sells a very small Super 8
movie camera suitable for HPR payloads, but they have announced that they
are dropping all of their rocketry products. Still, they should still be
able to point you in the correct direction regarding the camera.
5.1.3 What about Video? Camcorders are getting so small that they should
work. How hard is it to adapt one? How about broadcasting the image back?
This is a new area with much work going on, and some early successes to
report. There are two ways of returning video from a rocket: record and
transmit.
5.1.3.1 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
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
horizontal (WRT the acceleration) over the heads. The explanation seems to
be that the grooved pulleys and tape guides have no problem keeping the tape
tracking correctly, even at 10 or 20 gees (tape's pretty light!), but if
you place the cassette with its spools vertical (i.e. the tape horizontal)
the tape tends to pull freely out of the cassette under acceleration and
tension is lost. No tension, no picture - JH]
5.1.3.2 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.
The Jan/Feb '93 issue of HPRM had two articles on broadcast video systems;
both, coincidentally, being homebrew reworkings of the Lionel "railscope"
miniature CCD camera. While being admittedly low-res, the systems can be
made quite light. The version by Dan Green had a fight ready weight of only
3 oz which makes it capable of being flown by a "C" motor!
The May/June '93 HPRM has a fairly lightweight article on a video transmitter
project called the "ICU2" (get it?)
The amateur "AmSpace" project outlined in the April '94 issue of HPRM
contains a live video downlink as part of it's sizable instrument package.
Commercial - If you feel like dropping a kilobuck on the hardware, Hans
Schneider (Plainsboro, NJ) runs a much improved ad (compared to his previous
one) in HPRM offering an HPR based color/sound video broadcast system
(including rocket) for a staggering $975 (but you get free shipping :-)
is a good contact for miniature video cameras (B&W and color), transmitters,
and receivers. Note that the operation of this transmitter requires a ham
radio license. See the address section for the address of these companies.
----------------------------
5.2 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 unforeseeable (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!
5.2.1 What sorts of data transmitters are available for rockets? What's been
flown in the past?
5.2.1.1 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 publicly
flown at NARAM 2 in 1960. It was a simple multi*** 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."
5.2.1.2 Foxmitter - Using the same basic encoding principle (and still
broadcasting on the Citizens' 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! A smaller/lighter
Foxmitter III was described in the Sept '71 issue.
In a couple of 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.
5.2.1.3 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 "*** 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.
5.2.1.4 Current - Adept Rocketry in Broomfield, CO sells a large range of
electronic products including both transmitters and data loggers. I've
grouped them together in the next section.
5.2.2 I don't want to bother with ground based recievers and recorders. What
sorts of Data Logging products are available?
5.2.2.1 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.
5.2.2.2 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. For more info on this
device, see "Transolve Corp." below.
The April, '94 issue of HPRM has a remarkably detailed article on the
"Microbats" project. This is a very large ("M" motor) HPR project that
is *very* heavily instrumented. The Rocket Data Acquisition System (RDAS)
consisted of a 35mm camera, altimeter, 2-axis accelerometers (horizontal and
verticle) plus a sophisticated timer-based control system (see Part 6 for
more on timer-controllers). The article includes theoretical predicitions
and compares it to the actual flight data.
In that same issue there is an introductory level article on an amateur
rocketry project called "AmSpace" which is designed to put the first non-
professional payload up to orbital altitudes (80 KM or 50 miles). The
payload will contain a significant amount of data logging of internal
parameters. There are accelerometers which will be integrated real time
to give velocity and altitude information, sensors to monitor pressures and
temperatures in the propulsion system, a GPS to track the rocket's position
relative to the earth and a magnetometer to control the steerable paraglider
chute to help return the payload to the launch site. The data logging will
be complemented by an RF data downlink plus amateur TV.
5.2.2.3 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 upload data from 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. Note: this company has not been answering its mail,
according to some r.m.r posters, and may be out of business.
Transolve Corp, Cleveland, OH - Sells the "A2 Micro Altimeter" which sounds
suspiciously like a production version of the _Radio-Electronics_ system
articles in _Radio-Electronics_ are thinly veiled adverti***ts. In this
case, it would appear that the author was writing on behalf of Transolve, in
order to sell the kit." John is correct, especially considering that the
author is the CEO of Transolve :-) A detailed review of the A2 was printed
in the July/August issue of Sport Rocketry magazine.
Adept Rocketry, Broomfield, CO - Has quite a line of electronic products
including peak reading & continuous altimeters and on-board computers. A
level is a $49 altimeter. Relatively small, you launch it into the air, and
when it returns it will be beeping out the maximum altitude (beep-beep-beep
...beep-beep...beep = 321 feet). A $79 version will log the altitude data
into EPROM for later recovery and downloading. They also have] on-board
computers (four models, most with built-in altimeters)."
"Telemetry/Tracking Transmitters and Receivers - Prices on transmitters are
expected to be in the range of $10 to $30, with receivers reaching higher
prices. However, at least one low cost receiver is planned, and in a few
cases you'll be able to receive data on a standard FM radio. Ground Support
Devices will be available for decoding and recording data in the field, and
PC compatible software is being written for plotting and analyzing the
recorded flight data."
Finally, we have from the r.m.r address list the following entries on which
I have no info outside of the tag line in their list entry:
Langley Autosystems in Sunnyvale, CA is listed with "Datastick on-board
computer"
High Technology Flight in Ypsilanti, MI sells "Electronic Payloads".
[Moderator's note: There are quite a few electronic timers, beepers and even
sophisticated micro-p based flight controllers sold by several companies.
These are usually used to control staging, recovery deployment and aid in the
recovery itself. While of the same general nature as the electronic payloads
just described, they are not technically payloads, but rather part of the
carrier rocket itself. They have therefore been grouped togehter in Part 6.2,
Guidance Systems, since it seems a more appropriate fit.
5.2.3 Sample collection - Has anyone actually brought stuff back from a
rocket flight?
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
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.
----------------------------
5.3 What about biological payloads? Can I fly mice or toads?
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 than all other
bio-payloads combined, stay out of Vertibrata. Anything with a backbone
is a definite no-no.
----------------------------
5.4 Are there any payloads I can fly that really don't *do* anything? You know,
Just for fun.
This section is on Novelty Payloads, the catch-all for everything else
your rocket might carry besides 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.
5.4.1 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, the standard contest
payload (even though Tripoli doesn't officially run contests) is larger
than life :-) They decided 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 at least 2.25" diameter at some point and be able to hold 16
fluid ounces 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." Credit for the first successful eggloft is given to the
same Hans/Scott team that flew the first movie camera (q.v.)
5.4.2 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.
Variations on this type of rocket have been around for some time. Plans for
"concept" rocket called "The Purple People Eater" by Ken Brown were published
in the December, 1980 issue of _Model Rocketeer_ magazine. The model drops
various types of streamers and "flutterers" at ejection. A larger version of
34's sport range in August, 1992.
Expanding on the concept, the "ZIA Spacemodelers Sport Design Notebook"
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 *** 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 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. Estes once thought of
dropping this from their lineup due to poor sales (it goes against the
grain of most rocketeers who do everything in their power to keep their
rockets *together* :-) but having witnessed them, I can say they're great
crowd pleasers!
a November, 1992 Tripoli launch the announcer said, "This one's going to
eject a roll of toilet paper." Sure enough, an extremely long yellow
streamer was seen coming down. It actually turned out to be a roll of that
yellow polyethylene "CAUTION" streamer that you can get at hardware stores
for cordoning off excavation sites. He had about a ten minute winding-up job.
down in the southland: "A DARS member, Jimmy Cleek, has built a 3" diameter
rocket he calls 'Tomato Rain'. True to its name, he launches several small
tomatoes and ejects them as part of its regular flight plan. He has also
ejected candy at an Easter launch. Jack Sprague, also of DARS, has a model
in which he ejects up to 1/2 dozen MIRV's at apogee. The MIRV's are the
little Nerf-darts you can get at toy stores. Another favorite payload to
eject at DARS demo launches is a number of pennies, each taped to the end
of a 6" x 1 1/2" crepe paper streamer. Makes for a great demo flight. All
variations on the same theme....
5.4.3 Night Flying payloads
This is another of those subjects that comes *really* close to falling over
into Part 6, because all of the following are used as recovery aids if
you lanch at night. At first blush, night flying seems really silly. After
all, except for the initial glaring brightness of the motor burn, you
can't see it. What's the point? It all seems vaguely illegal somehow :-)
he posted: "Having recently read the FAQ section on payloads, I was a bit
surprised by the total lack of discussion on something that has intrigued
me for some time: launching at night.
"I always thought it would be possible by carrying some sort of bright
strobe for a payload. Either ultra-bright LEDs or some xenon flash-tube
strobes in a clear payload section. The lack of discussion leads me to
believe that I must be missing something unsurmountable."
with his suggestion: "Try Cyalume glow sticks. They're quite visible a
long way up, and can be quite cheap (buy them right after Hallowe'en). I
usually tape them with clear tape to the shock cord."
This is a very common suggestion for night launches, and was included
in what is perhaps the definitive article on night flying, published in
the April, 1994 issue of _Sport Rocketry_ magazine. In it, author David
Sollberger describes several type of Night Illiumination Tracking Equipment
(NITE, get it?) including chemical (the Cyalume sticks), high intensity
LED's, incandescent bulbs and strobes. They are all evaluated for cost,
effectiveness and complexity. Several designs of varying completeness
are included.
Complementing the NITE article in the same issue is a very complete design
for a High Intensity Strobe by Mort Binstock.