808 Keychain Camera Information

On TRF, JimCatz gave a good reference website for questions about the 808 Keychain Camera:

http://www.chucklohr.com/808/index.shtml

Check Amazon and some of the rocketry vendors. These cameras sell as low as $6.11 !!!
I'm not recommending any camera for $6.11. 
I simply did a search and found a low price.

An 808 style camera was used on my two engine cluster rocket, the Big Girtha.
It was carried away by a thermal and I thought it was lost.
The rocket and camera sat in a strawberry field for who knows how long.
Somebody returned the rocket, it was destroyed by rain and exposure.

The video and audio from the camera was fine!
The camera video still works, but now there is no audio.

The whole story is HERE

The Big Girtha Saga!

My original Big Girtha was a two engine cluster built using most of the parts from a Quest Big Betty kit. I'd flown it a few times before losing it at a TTRA launch.
On February 16 it was windy and I still switched out the two B6-4s for C6-5 engines.

I had a new spy cam running, you can see it taped to the side.
Descent was good until it hit a thermal and drifted over the trees to the east side of the field. I chased it down but after a half hour of looking it couldn't be found.

Brian Urban emailed to let me know the rocket was found and being held in the TTRA equipment trailer. I picked up the model two months later but the small video camera was gone!
Brian told me he removed the camera for safe keeping. He didn't have it with him that day.
The rocket was waterlogged and weather beaten. Parts were salvaged and another Girtha was built.
Brian brought the camera this last Saturday, June 15 at the TTRA launch.

I was very curious to see if the Micro SD card video was still good:
You can see the video HERE

The video was much clearer before downloading to YouTube.

Big Girtha Build Finished

The re-built Big Girtha is ready for flight, ready for today's Tampa TTRA launch, June 15, 2013!
Changes from the first version:
Five red barber pole stripes instead of four
A slightly smaller parachute so I'll get it back next time.

Big Girtha Build Part 19, Odds and Ends

Normally a baffle like this would be used to couple two body tubes together. I had to install this one from the top.

The fit was tight so I didn't feel good about putting glue into the tube first then having it "freeze" in the wrong spot.

It was dry slid into the tube using the end of my straightedge.
Figuring space for the parachute and nose cone shoulder I felt it needed to be 8 1//2" from the top.

Fillets were applied using a long dowel with rounded ends.

The shock cord anchor was made up "Centuri" style using a piece of scrap body tube.
This mount fits the inside curvature of the body tube better than a tri-fold mount could.

This style of mount won't work in body tubes smaller than a BT-55 size.
It might block the parachute ejection.

From the front end you can see the shock cord mount set down 2" from the top.
Below that is the installed and filleted baffle.

The picture makes the baffle look like it is five feet down the tube!
I've got a little paint to clean up on the inside of the body tube.

Big Girtha Build Part 18, Trim Tape Placement

I used the same paper to trim the diagonal stripe ends.

Wrap it around and trim along the edge.
In time the tape will shrink some, you'll want to allow for overlap.

Here I'm trimming the bottom end of the diagonals.

It looks pretty good like this and could be left as is.

The final two black horizontal stripes are layed down over the red diagonal ends.

Years back many catalog models were trimmed using colored electrical tape.
This is easier than you might think.
Once the tape sets down, it won't lift easily.

Always print extra decals!
This one was left over from the first build.

Big Girtha Build Part 17, Trim Tape Placement

Before laying down the barber pole strips -
The name decal was set on dry to be sure there was enough space for it.

Mark the five ticks at the top of the red strip.

Directly below in line with the upper marks, draw five more ticks for the bottom end of the diagonal stripes.
Start the strip at the top, centered over the pencil tick.
The end of the tape strip will be centered over the lower tick to the left of the upper one.

It took a few tries to get the electrical tape strip lined up.
The tape is flexible and stretches.

Don't worry about the ends yet, they'll be trimmed later.

Look from the rear and get the tape lines as straight as possible.
It's easy to lay them down with a curve in it.

Big Girtha Build Part 16, Trim Tape Placement

I started the colored electrical tape wraps from the top down.
The strips were cut to 5/16" thick on my patio door glass. Use a new blade and a metal straightedge.

The wraps were all started in line with the launch lug.
Be sure to overlap the tape strip ends by about 1/8". Over time the tape will shrink up a bit.

When laying down the lines try not to stretch the tape. Let it relax before setting it down.

Look close at the first picture and you can see a paper strip wrap under the red tape. The straight paper wrap gives you something to line up the tape. If you follow the paper edge your ends should meet up perfectly.

The first Big Girtha had four red tape lines going barber pole style down the upper tube. I always thought it should have had five strips sitting a little closer together.

To find five even space marks on the strip -
The strip was wrapped around the 40mm tube and the overlap marked.

The circumference of the tube is a little under 5".
To divide the strip into five sections I set my ruler over it at an angle and the inches were marked.
When re-wrapped around the tube I had five even spaced marks for the five angled tape strips.

Big Girtha Build Part 15, Masking the Red

Here's the red paint after the first coat.
A second heavier coat followed.

After the Scotch tape masks were removed.
Two fins were left white.

The area above the fin can has a mask from red to white.
(The front of the body tube is turned down in the picture.)

This line will be covered by a strip of black electrical tape.
I sanded down the paint ridge a bit so it wouldn't show as much under the tape trim.

Big Girtha Build Part 14, Motor Mount Fix

Two ST-7 tubes side by side fit very well in the Big Betty 40mm tube.
I thought I might get by with just the single, sealed centering ring at the top of the mount.
When slid into the tube there as a little wiggle on the sides. The fit was good but not great.
In the spare parts box I had a pair of rings made for a ST-16 tube.
I traced around the slightly smaller 40 mm centering ring.

If your scissors are sharp you can get a smoother curve cut than you can with a knife.
Cut just on the outside of the pencil line so you can sand it to fit after gluing.
(Yes, the center disks were thrown into the spare parts box - you never know when you'll need a ST-7 block.)

Half circles were punched to allow engine hook movement.

Here's the crescent rings glued in place.
The rings were glued and sat right on the rear edge top of the tape wraps.
After some minor sanding, the fit in the tube is more solid.

Big Girtha Build Part 13, Epoxy Fillets

Pick up any excess epoxy from the ends with a Q-tip dipped in alcohol.
Set the model horizontal and let the two facing fillets start to set up.
Epoxy will run! Be sure the fillets are level while they set up.

After the epoxy sets up for a few minutes, you can pull up the tape dams. While the epoxy is still be tacky you can smooth the edges where the tape dams were.

I didn't get a picture of this -
Put on a disposable glove and pull the vinyl over your fillet finger tight.
Dip your finger in alcohol and shake off an excess drip but leave the finger wet.

Run you wet finger down the still setting fillet.
Your finger should be wet enough that the alcohol can break down the edge and smooth it into the body tube contour.

Let these two fillets dry before moving onto the next facing fillets.

After you spray on primer you can easily see any high or low areas in the fillets.
Wrap some 220 grit sandpaper around the same dowel and sand down any high areas.
Follow with another shot of primer/filler and sanding down to 400 grit.

Big Girtha Build Part 12, Epoxy Fillets

Before you mix up epoxy, have everything you'll need close at hand:
Alcohol (to smooth edges and clean up)
Disposable gloves (to protect your hands)
Q-tips (to clean up ends and edges)
1/4" diameter Dowel (Clean and sanded smooth)
Paper towels

Mix up the two part epoxy on waxed paper.
You won't need much, you are doing just two facing fillets at a time.
Squeeze out the A and B parts. In the picture each part is about the size of a dime. It'll start to spread out on it's own.

I transfer the mixed epoxy to the fillet area using a toothpick.
Set a drop in the joint and drag it down the fillet area.

Be careful at the leading edge tip. It's easy to let too much epoxy end up on the ends.

Dip the dowel end in some alcohol and shake off the excess.

Run the dowel down the epoxy. Excess epoxy will be pushed up on the masking tape. Some excess will be taken off with the dowel.

Wipe the dowel end off on a paper towel.

Big Girtha Build Part 11, Epoxy Fillets

This model is a two engine cluster and epoxy fillets aren't really needed. White glue fillets would be strong enough.
But on a larger model the fillets could be wider.

Before taping up the fins decide on the fillet width.
Taking a tip from Crazy Jim on TRF -
I used a 1/4" dowel to mark the mask lines.
The dowel end is marked with a pencil. The marked dowel is dragged down the root edge.. This makes two even lines one either side of the root edge.

Before laying down the masking tape I added a coat of medium CA over the paper covered fin. I was concerned the paper covering might lift when the tape was removed later on.
The CA was applied over the area where the tape mask will be.

The tape is hard to see in the picture, but the edge is just to the outside of the pencil lines transferred earlier with the dowel.

Big Girtha Build Part 10, Gluing Four Fins Evenly

Three fin models stand on their own without wobbling.
Four finned models that stand vertically on the fin tips require a few extra alignment steps.

It's a bit tough to see the rear end of the root edge when gluing these fins on. You want the intersection of the root edge and trailing edge right at the end of the body tube.
Enlarge the picture and you can see small tick marks at the end of the leading edge. The pencil ticks give you one less thing to worry about before the glue sets up.

Like in previous builds, a paper strip was wrapped around the start of the leading edge.
Glue the first fin on then wrap and tape the alignment strip around the tube. This isn't really needed, but gives you another point of alignment.

TIP: To get rid of the four fin standing "wobble":

Glue on (only) three fins as normal.
The fourth fin decides if the rocket stands without wobbling.

Apply glue to the root edge of the fourth fin.
Set the fourth fin on the remaining alignment line.

While the glue is just starting to set up on the fourth fin root, stand the model on a flat even surface.
With the glue still wet you can slide the root edge up or down until all the fins are even and the rocket doesn't wobble.
It won't take much movement to get the final fourth fin edge to the right location.

To find the C/G, the model was dry fitted with engines, wadding and parachute.
The 3/16" lug center was glued on the center of gravity.

Before any paint is sprayed, erase any exposed pencil lines.

Big Girtha Rebuild Part 9 Engine Mount

Cut out the circles as best you can with a sharp knife.







You can sand to the edges of the inside engine blocks using 220 grit on a dowel or back end of a Sharpie.

Here's the finished mount - no chance of the ejection charge blowing out the back.

The two engine mount tubes fit close to the inside walls of the Quest 40mm tubing. Ideally you should have a second lower centering ring but the fit is close enough it might not be needed.

Big Girtha Rebuild Part 8 Engine Mount

On of the Big Betty 18mm centering rings was glued to the top of the two engine tubes. The engine blocks and tube ends were sanded flat for a better glue bond.
Those holes in the top center will have to be filled or the ejection charge would exit out the rear.

Using the second centering ring, a circle was drawn on scrap mat board.
The two crescent shaped cuts were made using an engine block.

I had to cut two filler pieces before I got it right.
To fit, the outside circle ended up cut outside the pencil line.
The filler piece was glued in place.

Use the inside of the engine block to mark a pencil circle.

The rest of the circles are cut out to allow more of the ejection to pass through.

Big Girtha Rebuild Part 7 Engine Mount

I rarely use the yellow or blue engine mount tubes supplied in kits. They are usually too thin.

The two substituted ST-7 engine mount tubes fit pretty well, side by side in the Big Betty's 40mm tube.
Test fit both to check the engine hook movement. I turned them in to the center a bit for more clearance.

A line was drawn down the engine tubes to make sure the hooks were in the right alignment.

Draw the lines over the top and bottom for easier reference when glued together.

The tubes wouldn't sit close with the electrical tape wraps.
Strips of card stock were glued down the lines to make the sides even for better gluing.