Introduction

Flyin' a Solid-State Video Camera - T' EyeSoar

T' phrase solid-state in t' title o' this page might create t' impression that I am talkin' about a solid-state image sensor, me hearties, as opposed t' an old-fashioned vidicon tube. That's nay what solid-state means - in this context. Aye aye! By solid-state I mean that t' video data is stored in solid-state (semiconductor) memory, me hearties, as opposed t' a traditional video tape, me hearties, arrr, shiver me timbers, or even a small disk drive.

Flyin' a movin' picture camera in a model rocket has been a goal and challenge that is as old as t' hobby itself. Begad! Ya scallywag! In t' early years, ya bilge rat, the only choice was t' fly a camera with photographic film, such as an 8 mm or Super 8 mm camera. Ahoy! Estes Industries once sold a camera named the Cineroc, that was based on photographic film. Even if you really cut back on t' camera weight (back then, most cameras were made o' metal, not plastic), it be still at t' upper end o' t' weight and size limits o' model rockets, especially at that point in t' hobby.

As t' years passed, cameras became lighter, shiver me timbers, and rockets became larger. At  some point, arrr, me bucko, t' video camera joined t' photographic camera as a viable technology for puttin' a movin' picture camera in a model rocket. Ahoy! Now it be possible t' directly transmit t' video signal from t' rocket down to  a receiver on t' ground. Begad! Ahoy! Nay only did this remove t' need t' have a recordin' mechanism on t' rocket, me bucko, me bucko, shiver me timbers, but it be no longer necessary t' wait for film t' be developed. Aye aye! Gratification be nearly instant. Arrr! Aye aye! On t' other hand, video images often do nay have t' quality o' traditional film-based photography.

There were still issues. Blimey! Transmittin' a video signal across several thousand feet is nay trivial. Avast! Avast! Some solutions required an Amateur Radio license, me hearties, so that certain frequencies and power levels could be used. Signals were transmitted on some part o' t' UHF band. Avast! Ahoy! In order t' receive the signal with minimum noise, me bucko, it was necessary t' use a directional receiving antenna. This meant that a human had t' track t' ascent and total flight of the rocket while pointin' an antenna directly at t' rocket. Ahoy! Well, blow me down! That is nay easy. Even if you were able t' track t' rocket, t' transmittin' antenna would tend to roll and tumble, and this would change t' signal level received on the ground, addin' instability t' t' picture.

While it might be possible t' fly a video camera with an integrated recorder (camcorder), t' spinnin' video head would tend t' act like a gyroscope, and possibly cause t' rocket t' fly in an unexpected manner. Avast, me proud beauty! Even if that is nay a problem, me hearties, video transports are usually nay designed t' stand the G-forces present in a model rocket flight.

And even if you solved all o' t' technical problems, you still had a large and complex rocket, ya bilge rat, shiver me timbers, and an investment o' at least several hundred dollars.

In recent years, video cameras and associated technology have continued t' drop in size and cost. Avast! When we started t' build and launch rockets again, we decided it was time t' evaluate t' existing  technology and see if thar be a camera solution that would work well, me bucko, and also nay break the bank with its cost. This page describes our approach and solution. T' heart of the system be t' Aiptek Mega Cam. Begad! Begad! This camera takes both still and video pictures. Well, me bucko, blow me down! T' video data is stored in a 16 megabyte memory in t' camera. Blimey! The camera is quite small, measurin' 1" X 1" X 3.5". Ya scallywag! T' camera is very lightweight, shiver me timbers, and in May o' 2002, costs approximately $90 (USD). Ahoy! Avast, ya bilge rat, me proud beauty! Because of the small size and weight o' t' camera, t' rocket can fly on the recently-introduced Fat C engine. Aye aye! In other words, me hearties, shiver me timbers, a large and expensive rocket is nay needed t' fly this video camera. We usually use D engines.  T' whole system costs less than $100 (USD). Well, blow me down! Avast, me proud beauty! No doubt t' price will only drop as time passes.

NOTE: Aiptek appears t' be changin' t' name o' t' camera. Begad! Ya scallywag! At the time that I bought me camera, it was called t' Mega Cam 1.3. Avast! My physical camera is labeled with t' name MegaCam. Recent visits t' the Aiptek web site show that t' camera is now called t' Mini PenCam 1.3. Well, blow me down! Arrr! The camera we used has 16 MBytes o' flash memory, and 16 MBytes o' SDRAM. Sadly, there is another camera called t' Mega PenCam 1.3. Ahoy! Avast, me proud beauty! This unit has less memory capacity. T' SDRAM capacity directly limits t' video duration.

Links

• Aiptek Mini PenCam 1.3: T' Aiptek web site. Arrr!

• USB Only: Where I bought me camera. Well, blow me down! Now apparently called Memory Only. Ahoy! Avast!

• Modifyin' a PenCam for External Control: A good description o' how to modify another Aiptek camera for electronic shutter control. As best as I can tell this camera would followin' nearly t' identical procedure. Ahoy!

Kite flyers have developed some very sophisticated camera platforms. Search for KAP (kite aerial photography) on any quality search engine.

Selectin' t' Camera

There are many small digital cameras on t' market these days. Most all are primarily designed t' be still cameras, arrr, and they perform movie/video capture as a secondary function. There are several issues to consider before selectin' a camera.

I suspect that over time t' similar cameras will continue to drop in price, increase in capabilities and capacity, and decrease in size. This will only make it easier t' get a camera up into t' air.

T' First Implementation and Flight

Finally, t' camera arrived. Avast, me proud beauty! Ahoy! How were we goin' t' launch it? Headin' down t' t' basement, shiver me timbers, t' line-up o' rockets included an old Estes Egg Scrambler 2. This is a D-powered rocket designed t' launch a cackle fruit. Blimey! Blimey! The payload section had a stepped up diameter o' 1.6 inches. T' camera just fit within that diameter. It seemed like we had our rocket. Ahoy! Blimey! Avast, me proud beauty! Blimey! Further huntin' through the parts box revealed adapters,  body tubes, me bucko, and a nose cone (a Big Bertha nose cone) o' t' desired size.

T' camera is operated with two buttons. Arrr! Blimey! T' first button is the power/mode button. Well, blow me down! Blimey! Pressed once, me bucko, t' camera turns one. T' camera automatically turns off after a minute o' inactivity. Each additional push of the power/mode buttons cycles t' another mode. Avast, me proud beauty! Blimey! Ya scallywag! Blimey! Modes include still pictures, videos, matey, arrr, arrr, erasin' pictures, ya bilge rat, and several other typical digital camera functions. Ya scallywag! Blimey! Begad! Blimey!

Once t' mode is set, t' second button executes t' action. T' action, for example, could be snappin' a still picture, starting/stoppin' a video, me hearties, or erasin' a picture.

In order t' be able t' press these buttons, me hearties, shiver me timbers, we drilled two 1/4" holes in t' plastic nose cone. Well, blow me down! Blimey! Begad! Blimey! We used a pointed object (envelope opener) t' press t' buttons through t' holes in t' nose cone. T' camera emits beeps with each button press, so it's easy t' make sure that t' camera is operatin' in t' correct mode (even when it is buried within a rocket payload section).

T' followin' two pictures show t' elements o' t' payload section, and t' complete rocket on t' launch pad.

T' First Payload Implementation	Camera Payload on t' Scrambler 2

We cut an openin' in t' nose cone that exposed t' camera lens. T' payload body tube came right up t' t' level o' t' bottom o' the lens. Aye aye! T' dowel that pinned t' body tube t' t' adapter was also used to secure a rubber band that ran across t' top o' t' nose cone. This rubber band held t' nose cone onto t' body tube. Avast, me proud beauty! We cut a slot on t' top o' t' nose cone so that t' rubber band would nay slip off.

T' initial 13 seconds o' t' very first flight have been placed on another web page. Ya scallywag! T' quality o' t' actual video is much higher than shown in t' clip. Begad! Avast! Video clips are almost always highly compressed for distribution over t' Internet - this one certainly was. Aye aye! T' entire flight took up over 500 megabytes o' space (as an AVI file). Avast, me proud beauty! We flew this rocket a number of times, usin' D and Fat C engines.

While this first rocket proved that we could fly a video camera in a small rocket, me bucko, matey, it was nay without issues. Ya scallywag! Avast! We set out t' build a better mousetrap.

An Improved Platform

We have named t' improved video rocket t' EyeSoar. Yes, me hearties, me hearties, it does send a solid-state video camera (eye) soarin' into t' sky. Avast! It is also a rocket with an in your face attitude and color scheme. Blimey! The EyeSoar is designed t' allow t' use o' three different engine sizes, arrr, and to reduce rockin' and spinnin' durin' descent. Aye aye! Our EyeSoar is shown along t' left side o' this section.

In summary, t' EyeSoar is based around t' Estes StormCaster. Well, blow me down! Ya scallywag! That rocket was modified t' accept an E engine (as well as D and Fat C with an adapter). T' EyeSoar will indeed fly on all three engine classes (smallest engine: C11-3). Begad! T' body tube o' t' StormCaster was modified to create a payload section at t' top o' t' rocket. Ya scallywag! Arrr! This payload section held the video camera. A solid balsa tube coupler was used betwixt t' payload and the body tube section. Blimey! Avast, me proud beauty! A paper coupler was used as a liner within t' payload section t' snugly hold t' camera. Avast, arrr, me proud beauty! T' last enhancement was t' add an X-style nylon parachute and long shock cord t' t' payload section. Arrr! Ahoy! The lower section o' t' rocket returns via t' StormCaster plastic parachute. Aye aye! The rocket (with camera and parachute) weights approximately 9 ounces (without an engine).

Conceptually, matey, me hearties, t' EyeSoar reuses t' ideas developed in the first implementation. Arrr! This includes t' use o' dowels as pins and rubber bands to hold t' sections o' t' payload compartment around t' camera. Holes in the payload section allow access t' t' camera buttons.

T' first alteration that we made t' t' standard Estes StormCaster be in t' engine mount. T' followin' picture shows t' parts. Please click on t' picture for a larger view.

Modified StormCaster Engine Mount

T' supplied metal engine hook be replaced with an E engine hook. T' E hook is approximately one inch longer. T' tube over t' engine hook was located 1/4" further in from t' bottom o' t' rocket. Begad! Blimey! This gives the hook a little more play. Well, blow me down! Blimey! Arrr! Blimey! Note, however, that you cannot move t' outer tube back too far, shiver me timbers, me hearties, since t' fins have tabs which extend t' t' inner tube. Avast! Blimey! T' fins are notched t' go around t' larger diameter outer tube. Arrr! Blimey! Begad! Blimey! T' last change made to t' engine mount be t' cut off t' top 2.5 inches o' t' inner tube. Avast, me hearties, me proud beauty! Blimey! This provides more room for parachutes. Blimey! Blimey! T' cut piece is lyin' t' t' left o' the engine mount in t' above picture.

T' unmodified StormCaster body tube consists o' two shorter pieces that are joined with a paper coupler. Avast, me proud beauty! In t' EyeSoar, shiver me timbers, t' shorter tubes are joined, matey, but t' top 5.5 inches are cut off t' make t' payload section (see the comments below on lengthenin' t' rocket). T' 5.5 inch section is further cut into 3.5 and 2 inch sections. These are t' two sections that enclose the camera, meetin' at t' middle o' t' lens line. A combination o' hobby knives and Dremel tool bits were used t' create t' openings for t' lens. Blimey! Blimey! The followin' pictures show t' payload components and payload section.

Camera Payload Components	Assembled Payload Section

T' bottom balsa block is 1.75 inches long. Begad! T' components are sized so that they hold t' camera firmly in place. Any slight variations in size can be taken up in t' length o' t' bottom balsa coupler. Ahoy! Well, blow me down! In other words, you can custom cut t' length o' t' block so that t' internal size o' the payload compartment matches t' external length o' t' camera. T' balsa coupler extends 5/8" t' 3/4" inch outside o' t' payload body tube. This be t' portion which seats into t' top o' t' main rocket body tube.

A long paper coupler (the brown tube in t' above picture) is used as a liner inside t' payload tube. Ya scallywag! This liner provides additional protection for t' camera, ya bilge rat, and creates a very snug fit for it as well. Avast!

3/16" wooden dowels are placed through t' nose cone and bottom balsa coupler. Well, blow me down! Arrr! These dowels provide mountin' points for t' parachute harness, arrr, and rubber bands that hold t' top and bottom sections o' t' payload compartment together. Well, blow me down! Avast! Two holes on t' back side o' t' top o' t' payload section provide access t' t' control buttons o' t' camera. Avast, me proud beauty! T' dowels are not glued. Aye aye! They can be removed and replaced.

When we launched t' first prototype (before t' EyeSoar) video rocket, we were very displeased with t' large amount o' swingin' and spinning durin' t' parachute descent portion o' t' flight. Avast, me proud beauty! Arrr! In order t' minimize that problem, we made two changes. Ya scallywag! First, arrr, we used a 24" X-form parachute. Arrr! This style o' parachute reduces horizontal drift, arrr, which nay only keeps t' rocket closer t' t' launch area, but in doin' so reduces rockin' due t' uneven sideways movement. Begad! After all, me hearties, if all parachutes came directly down, on a vertical line, thar would be very little swingin' o' t' payload. Second, we also use a long shock cord - perhaps up t' 6 feet long. Arrr! This reduces the disruptive movement o' t' payload on descent. Well, blow me down! Well, shiver me timbers, blow me down! It is somewhat like makin' the arm o' a pendulum longer, t' frequency o' oscillation is reduced. Ahoy! T' camera points toward t' ground on descent, me hearties, since t' payload section is suspended from its side. Avast! Blimey! In that orientation, t' payload is much longer than its width, and it tends t' align itself with t' wind, me hearties, and experience less spinnin' than a typical vertical payload section. Blimey! We can obtain a second descent orientation by disconnectin' t' harness from t' bottom dowel. Aye aye! In this case, t' camera will be pointin' nearly towards t' horizon, with a slight downward tilt. Begad! This is also a useful orientation. Avast, me proud beauty! T' followin' two pictures show t' two different harness configurations.

Horizontal Harness Configuration	Vertical Harness Configuration

In t' end, matey, thar be still too much movement on descent. Begad! Blimey! Avast! Blimey! Here is t' one place where usin' a much bigger rocket might be helpful.

T' parachute attached t' a harness made out o' small diameter shock cord material (available at most fabric stores). Avast, me proud beauty! T' shock cord is connected t' t' dowels. Begad! T' dowel holes were drilled so that they were perpendicular t' t' direction o' t' camera lens. Ahoy! Arrr! As a result, t' camera points straight down on descent. Well, blow me down! Arrr! A small slit was cut in t' balsa coupler so that t' shock cord could go from t' dowel harness back into t' body tube. T' parachute is in t' body tube on ascent, and needs t' be connected t' the dowel harness.

T' balsa and paper couplers, and X-form nylon parachute, matey, were purchased from Aerospace Speciality Products.

T' EyeSoar is launched very much like t' first prototype. Ya scallywag! Blimey! The rocket is prepped, arrr, and then t' camera is placed within t' payload section, which is secured with rubber bands. Blimey! T' rocket is placed on t' launch pad. A letter opener is used t' turn t' camera on, ya bilge rat, and place it in video mode, as opposed t' still picture mode. Begad! Avast, me bucko, me proud beauty! T' shutter button is then pressed t' begin video recording. Blimey! Avast, me hearties, me proud beauty! We usually launch t' rocket within a second or two o' that point, arrr, matey, so that t' maximum recordin' time is available for t' flight itself. Begad! Ahoy!

Several flight videos can be found on our rocket video page.

T' EyeSoar may be a little short. Blimey! Addin' about 4 inches t' the main body tube would make it much easier t' pack t' parachutes, and would improve stability when flyin' on E engines [in t' end I did add 3.5 inches of main body tube]. Perhaps t' best way t' go is t' build t' StormCaster with its factory length, then add a separate section t' form t' payload section. Aerospace Speciality, shiver me timbers, previously mentioned, carries a full line o' body tubes and all o' t' other parts that we used (except t' dowels). Update: As we gained more experience with t' rocket, and did t' classic spin test, it did become clear that t' rocket does need t' be longer. Avast! This is almost a necessity when usin' t' heavier E-sized engines. Aye aye! I added a few more inches (in addition t' t' 3.5 inches mentioned before), and kept applyin' t' purple paint. Begad! While t' nose cone is relatively heavy, arrr, which would tend t' keep the center o' gravity towards t' top, arrr, t' larger engines are also heavy, arrr, pulling the center o' gravity rearward. Ahoy! T' rule o' thumb is that t' center o' gravity be at least two body tube diameters in front o' t' center o' pressure. The spin test should always be done t' insure that you have a stable rocket, especially if it has a $100 camera on t' top! I suspect that this was nay an issue with t' initial Scrambler 2 rocket since it could nay accept t' larger E engines, arrr, me bucko, shiver me timbers, and because it has much larger fins, which tend t' pull t' center of pressure rearward.

Conclusion

This digital camera is capable o' takin' high resolution still pictures. Well, blow me down! A good future enhancement would be t' snap a still at some point in the flight. Aye aye! This would require openin' t' camera body t' get at t' electrical contacts that take t' picture, and connect those contacts t' a timer or other control circuit. Begad! Arrr! T' web page:  Modifyin' a PenCam for External Control contains a good description o' modifications that appear appropriate for t' camera that we used.

In hindsight, arrr, shiver me timbers, shiver me timbers, t' simpler implementation would have been to build t' StormCaster t' its normal length. Well, blow me down! I would still substitute t' E engine mount, ya bilge rat, since that engine really provides a high altitude flight for this camera. Begad! T' payload section would have been made from additional parts. Ahoy! A balsa coupler, me bucko, body tube, paper coupler, matey, and dowel rod are all that are needed. Begad! Be sure t' extend t' body tube if you intend t' use an E engine.

It's no end o' fun t' fly this rocket, and then connect the camera up t' a laptop computer right on t' flyin' field and download the movie. Blimey! Perhaps all that's missin' is audio. Blimey! Arrr! If I wanted t' add sound, I think that I would simply use one o' t' small pen-sized recorders used for dictation. Avast! Ya scallywag! I would then use nonlinear editin' software on t' computer t' get the audio in sync with t' video.