Camera+rocket+(Level+1+and+Level+2

CAMERA ROCKET BUILT BY DAVE THOMSON

Image above is the rocket heading skyward on 4xG40 motors at a SERFS Yatesbury meeting in 1997. The conceptual design for this rocket was started back in 1995 after going to the Largs 1995 International Rocketry Weekend in Scotland. I had seen a programme on television at the same time called 'Rocket men'. This programme was broadcasted on channel four by on the 'Encounters' series. It showed how the amateurs in America did it including Denis Lamonth and Dave Crisally. It spurred me on to design and build a large high-powered rocket with a camera payload.

Not having access at that time to high-powered motors I was limited to clustering Estes 'D' motors. I concluded that 19 x D12 motors would fit into the base of the body tube and should provide enough thrust to get it off the ground a few hundred feet. This original design did not actually fly but was later converted to fly on 4xG Aerotech single use motors and then later still to fly on a single 38mm I211 RMS.

 **ROCKET CONSTRUCTION**

1) BODY TUBE The body of the rocket is made from 4.75inch (120mm) diameter A0 size drawing storage tubes. These are similar in weight to phenolic tubing but cost nothing! They are not as durable or as strong but are acceptable never the less. The worst part of making any rocket is to hide the spiral wound paper markings on the outer tube wall. Lots of careful rubbing and filling is required. I coat the outside with slightly watered down PVA glue when complete to seal and strengthen the tube ready for final coating. Gloss undercoat is brushed on and left to dry between rubbing down with a medium paper. Around 4 to 5 coats are required to give a good smooth spiral free finish. The topcoat is sprayed on lightly with car touch-up spray cans. Overall length is 7.5 feet. Weight without motors is 10lbs.

Decals are stick-on Solar-trim used in model aircraft, cut to shape and applied as required. The first version of this rocket had a one piece body and ply fins. The fins where through the wall but did not fix to the motor mount but instead were reinforced on the inside of the airframe. This gave a strong design and a removable motor cell. This arrangement flew three times in all. The last flight landed heavy at a SERFS meeting in Yatesbury and I had to rebuild the airframe.

I re-engineered the airframe into modular pieces so that it could be transported and repaired easier. The main body now has an upper section for the parachutes. This is slotted and screwed into a similar size lower motor/motor cell section. The motor mount is the same but the fins are now of a bolt on design.

Three slots have been cut into the tube the full length of the root cord of the fins. A tee section piece of aluminium (form B&Q) is then epoxyied to the inside of the tube for each slot with the Tee section protruding out from the side of the body. 4mm clearance holes are drilled in the aluminium to accept the bolt on fins. The fins are black Perspex cut to shape and drilled to mate up to the aluminium fin supports. This arrangement works well and has flown n an I211 motor perfectly. Spare fins are taken to the field just in case one is broken if landing on a rock etc.

Image above shows myself and my son David with the rocket at IRW1997 for it's first flight

The camera prism can be seen mounted on the nosecone. The flight was perfect and it did not get a scratch! Both parachutes fully opened and i attained my level 1 certificate.

More details of the IRW1998 meeting and more pictures of the flight can be seen on the IRW1998 reports page.



2) NOSE CONE

The most difficult part of a rocket to make is the nosecone. Commercially available nosecones do not fit the tubes I use. So I decided to make my own. It is a lot of work but it means that you can make it whatever size and shape you want. It is more satisfying also to know that you have make every part. The nosecone started life out as a 2inch thick sheet of polystyrene. This was cut into a number of circles that reduced down in diameter to simulate the basic shape required. These where then mounted on a central axis of M12 screwed rod with large ply washers at either end. The pieces were PVA glued together before the pieces where tightened up and left to dry. Next I made a basic homemade lathe. This used a standard drill as one end of the lathe into which on end of the screwed rod would be placed. The other end had a pillow block bearing to hold the screwed rod. These were mounted onto a wooden framework, which also had a wrist rest to steady tools against. The nose cone was turned at the drills slowest speed (only 2 speed) and a hacksaw was used to get the rough shape. When stopped the finish is very rough but very quickly comes to a smooth finish with rough and then medium sandpaper. Once the nosecone is smooth and the correct shape then it is covered with layers of fine fibreglass and PVA glue (thinned down). Normal epoxy resin cannot be used as it melts the foam. When dry this is then turned and smoothed. The surface is then coated with a thin layer of car body filler and turned and smoothed. This process is done a few times to get the smoothest finish. A number of coats of gloss under coat is then used to smooth out any final irregularities.

The nosecone has a large payload area that holds the timer and other equipment. An end plate is used to keep equipment in and doubles up as a shock cord mounting. The shock cord is 5mm diameter round cord available from B&Q. The other end of the cord is mounted onto a large shaped wooden block down inside the body tube that is glued and screwed in place. The shock cord can easily be examined or replaced if found to be damaged.



3) MOTOR MOUNT The motor mount was designed to be interchangeable so that future larger motors could be used. The motormount cell is removable for inspection/repair and is bolted to the airframe. A number of different types have been used and are detailed below. TYPE1

TYPE 2 This motor mount was developed for the 1997 IRW meeting at Largs. The mount was designed for 4xG Aerotech single use motors. The motor mount is made of two layers of thin ply separated by four 32mm high temperature waste pipe tubes (available from B&Q) some 12 inches long. The surfaces of which are roughened up before fixing into place with epoxy. The motor mount is removable and interchangeable by having strong fixings that go through the body of the rocket onto brackets which are part of the motor mount. An end stop in the tube is also given for extra security.
 * Not having access at that time to high-powered motors I was limited to clustering Estes 'D' motors. I concluded that 19 x D12 motors would fit into the base of the body tube and should provide enough thrust to get it off the ground a few hundred feet. If D12-3 motors where used then this short delay and plenty of ejection charge should pop the nose cone and deploy the chutes. In the end the rocket never flew on this motor configuration but my 4.75inch Patriot did. Details of this launch can be seen on its page. [|Patriot rocket page.] ||

TYPE 3 This motor mount was developed for the 1998 IRW meeting at Largs. The mount was original intended for a J350 motor but was subsequently downgraded to an I211 motor for a level 1 certification flight. This will now be used at Largs IRW 1999 for a J350 launch.

4) RECOVERY SYSTEM Uses two large ripstop nylon parachutes of homemade design and construction.

5) PAYLOAD SECTION The rocket was designed to accept a 35mm or 110 camera with an inertial trigger circuit that would fire the camera continuously from lift off until the film ran out. The camera looks out and back down the airframe through a 90-degree prism to capture the reducing ground, airframe, flame and smoke trail. The trigger circuit is home made from 555 timer modules. An inertia switch is used to trigger the system upon launch of the rocket. This allows for the system to be armed and only begin to take pictures at the moment of launch. The inertia switch is made from a small micro switch, above which a bar weight is pivoted to press against the switch but not have enough weight so as to trigger it at rest. When the rocket is launched the 'G' force on the bar triggers the micro switch. This enables the first timer which provides a timed period that allows the camera to take a full film and then disables the system. At the moment the first timer starts a second timer is enabled by the first. This second timer provides the timing pulses to the camera 'button' to take a picture. The time frame must be enough to allow the camera to take a picture and also to wind onto the next frame before the next trigger pulse arrives



A small hole is cut opposite the camera light sensor so that a correct exposure is taken. The camera is mounted firmly within the nosecone so that it will not move under launch and miss the opening in the side of the rocket.



A number of attempts have been made at taking pictures during launch. The first I forgot to turn on the timer!! The second the timer for some reason did not start until the nosecone had separated from the airframe. The third the same happened again. I got nice views of the parachutes unfolding and nice blue sky but nothing else. I am at present tweeking the system to have the inertia switch set to be more sensitive. If it does not work fully the next time then I will resort to a different method of starting the camera.

Above image is a test image. || Only sky and parachutes....... || No ground shots just more sky!! || 6) FLIGHT Flight details can be found on the reports pages,  IRW1997, IRW1998, UKRA99 and [|SERFS Yatesbury 97].
 * [[image:Camera_rocket04.jpg]]