Old Centuri Launcher LIA-77

Oh boy! More old crap!

Here's my favorite launcher from my teen years -
The Centuri LIA-77

You can't tell by the picture, but I sanded the band saw cut legs smooth and hit them with brush coats of Deft. On one of the legs is a Centuri decal.

This one is missing the bent metal Centuri blast deflector with micro clips attached. That's an Estes deflector that I found in the box with the launcher.



Here's the underside. The triangular piece of wood held the launch rod stuck through from the other side. The main triangular base piece was cut from 1/8" thick plywood.




With just two of the wing nuts removed, the outside legs would swing into the center for transport in my range box.

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/21    | توسط: فیروز قوچ داشی    |    | نظرات()

Semroc IRIS Build Part 10 Primer Band Mask

In this step, the tube will be marked for masking before spraying the primer.
There will be a strip mask for both bands and the fin root edges.

The bands will be glued on after the primer is sprayed and sanded. Later on, the fins will be glued on after they are painted red.

The fins are even with the back end of the body tube.

The rear of the wrap recess is marked with a pencil. Make this an accurate mark, it will effect how well the fin lines up with the end of the body tube later on. I double checked the position with a wrap of scrap paper.

The fin line (where the lower wrap would start) was extended up to the top of the body tube to mark the start point of the upper wrap band.

Notice the pencil line is not as wide as the band. This is the line for the width of the masking tape.

Primer will be sprayed before the bands are glued around the tube.


On the fins side, the wrap line was penciled around the tube.

Note on the upper leading edge of the fin there is another line. This is slightly below the taper in the fin. That's as high as the masking tape strip will go, not above the widest root edge of the fin.

This is a pretty smart way to make a double stepped wrap. The wide end is started first, the narrow band wraps over the top.

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/21    | توسط: فیروز قوچ داشی    |    | نظرات()

Semroc IRIS Build Part 9 Nose Cone Shoulder

The nose cone was filled at the same time with the fins

I mask off the base to keep the filler away from a good fitting nose cone shoulder






To get the best fit at the shoulder, I'll lightly rough up the body tube end (just the flat edge) with 220 grit sandpaper on a block. I don't want to take too much off or shorten the tube, just rough it up a bit.

To the left is the nose cone shoulder lip before.

The nose cone is reinserted into the tube and the balsa shoulder turned against the roughened tube end.
This rough tube actually sands down the rough shoulder lip a bit and gets a better fit to the body tube.

The picture to the right is the shoulder after using the roughened tube end to clean it up.

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/20    | توسط: فیروز قوچ داشی    |    | نظرات()

Centuri Letra-Line 2 Controller

This is my Centuri Letra-Line 2 Launch Controller from the early 1970s.

This had the same plastic handheld housing as the Centuri Letra-Line 1 but the "2" version connected to a car battery for those rare cluster launches.
The Letra Line 1 was an orange plastic, the Letra Line 2 was black.

You can see them both at Ninfinger HERE
It's complete, except for the safety key. It seems we were always losing those.
Look how thick the leads are! It would take a 12 volt battery to get enough current to the igniter. It's no wonder the wire weight could pull an igniter out of the engine nozzle.

For it's time, it was an ergonomic controller. It fit the hand better than the black Estes Electro-Launch Controller.

The catalog showed the housing to be black with a yellow button and safety key. Every plastic piece I received was black.

Back then I added some red tape to the launch button and brushed a little white paint on the raised Centuri name.
While I still used Estes launch equipment, these Centuri equivalents had a more professional flair.

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/20    | توسط: فیروز قوچ داشی    |    | نظرات()

Semroc IRIS Build Part 8 DIY Making A Coupler

Sand the joint edges with a block and keep them straight.

The other half of the coupler is around the back of the sanding block edge.






After a little sanding, here's the fit in the Series 11 IRIS tube.

To hold the joint together, a glue tab was made from card stock and glued in place.
Don't glue in the coupler yet!
Save it until after the paint is applied.

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/19    | توسط: فیروز قوچ داشی    |    | نظرات()

Semroc IRIS Build Part 7 DIY Making A Coupler

Making a coupler has been covered before, but this one and it's application is a bit different. I've made them out of body tubes but not from stiff, black fish paper before.

There was no Series 11 coupler in my parts box.
I do have a BT-55 coupler. It's slightly bigger so it'll be cut down to size.

It's been marked down it's length for the first cut.

This black fish paper it hard to cut through! Use a sharp knife.

After the cut was made, it was slipped into the Series 11 tube and the overhang marked with pencil.

Cut off the overhang a little oversize, to the side of the pencil line. You'll be sanding it down for the best fit.

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/19    | توسط: فیروز قوچ داشی    |    | نظرات()

Semroc IRIS Build Part 6 Paint Plan

Looking ahead, this is going to be a tricky mask.
The IRIS picture is from the Semroc.com website


I've decided to take the easy way out to get the split between the black and white sections of the main body.
Sure, I could mask it and cross my fingers, but this method will give you a very clean separation in half the masking time.

After an overall spray of white, the body tube will be masked, vertically "split" into quarters and sprayed for the black. The tape won't stop at the center point of the body tube, but go from top to bottom making four long alternating white and black stripes. It will look like a long white stripe, then a black stripe, another white and another black.

After everything is dry, the tube will be cut in half at the mid point. The two halves will be joined (dry, no glue yet) with a coupler. The upper half will get 1/4 turn giving the alternating white/black scheme. After making sure the match is good, the tubes will be glued together with the coupler.

If the tube cut is clean and the joint is square, this will give the body tube mask shown in the picture. Wish me luck!

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/18    | توسط: فیروز قوچ داشی    |    | نظرات()

Starship Epsilon at Centuri

I was reading through TRF archive and came across a thread by Bob Sanford. Bob worked for and developed the Initiator design for Enertek and later Aerotech.
He took a trip to Phoenix and Centuri in 1974.

He took pictures of the Centuri store, it was located in the front of the Centuri facility.
I'd seen this picture once before. I tried to copy it then, but the resolution was too low to be used.

Look in the upper left, there's a model at the end of the shelf, at an angle. That's my rocket!

When on vacation in 1972, I was lucky enough to get a behind the scenes tour of Centuri from Larry Brown. I had won the Centuri Photo Contest with that rocket, the Epsilon. The contest win got me a minibike and factory tour. I met Lee and Betty Piester and the R&D team. I presented the model to Larry after he showed us around.
I didn't know what happened to it until I saw the picture that Bob posted.

In the above picture, the model is displayed upside down.

This is how it should have sat!
This is a copy of the entry picture I sent to Centuri.

At least one of my designs made it to the factory.

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/18    | توسط: فیروز قوچ داشی    |    | نظرات()

Semroc IRIS Build Part 5 Fin Taper Fill

Using 400 grit on a block, lightly square the top of the edge taking off the remaining black ink.

NOTE: My fins don't actually taper to a real knife edge. the leading edge is squared off a little. If the fins were to go to a very sharp edge, the leading edge is weakened.

For now, leave the tape on for filling the balsa grain on the taper.

If the filler is sanded properly, it'll actually accentuate the leading edge line definition. After all that work, there's no reason to sand off the sharp edge now.


I'm filling just the leading edge taper first.

This is thinned Elmer's Carpenter's Wood Filler brushed on the leading edge above the masking tape line.





After sanding, the tape is removed. You can see how crisp the taped fill line is now.







next, fill and sand below where the taped edge was.

NOTE: Keep the filler OFF the root edge and out of the recesses for the fin mounts and body bands!
If you get a little filler over the taper line, carefully sand it off trying to keep that line straight and sharp.

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/17    | توسط: فیروز قوچ داشی    |    | نظرات()

Semroc IRIS Build Part 4 Fin Taper

This leading edge will be tapered down to almost a knife edge.

With balsa being a light color, it's hard to see how thick the leading edge is.
This idea was taken from how a luthier levels worn guitar frets. The frets are blackened with a permanent marker. When the top of the fret is filed down, the high spots are sanded off, the silver fret shows. The low worn areas remain black.

By blackening just the leading edge, you can clearly see how thick the knife edge is when sanding.

Don't go too slow when marking the balsa. You want just a light pass with the marker.
In the end, you'll want to sand off all of the black. Use too much ink and you will have to sand the leading edge too far, changing the shape of the fin.

I've sanded the taper using 220 grit on a block.
You can clearly see the thin black line left down the leading edge.

Look close, if you see a difference in the width of the remaining black line, sand that area to match the line width from end to end.



Before getting to the final width, switch over to 400 grit.

Here's the fin held up to a strong light. It's easy to see the taper with a back light. A little of the black line remains.

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/17    | توسط: فیروز قوچ داشی    |    | نظرات()

Semroc IRIS Build Part 3 Fin Taper

The Semroc instructions tell you to sand a taper to the leading edge.
That's a little vague, I wanted this rocket to at least "look" scale.

I found some instructions on JimZ's site for the Estes IRIS kit. You can see it HERE.
A small portion of the instructions are to the right.
It shows a leading edge wedge taper starting at the front band.

On the fin, the taper width looked to be a little over 1/4" or 9/32" wide.

The supplied fins are 3/32" thick. I set them on a flat surface and noticed the root edge wasn't perfectly flat, just a little off.

I carefully sanded the root edge flat, not wanting to take much off as it would change the fit of the tabs and body tube bands.

I went "old school" to sand the taper this time.
This technique goes back to the 1960s to get a clean, sanded line.

Masking tape is layed down at the start of the taper line on both sides. It acts as a "stop" so you won't sand past the desired edge. You do have to be careful though, use too rough a grit and you can sand through the tape edge!

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/16    | توسط: فیروز قوچ داشی    |    | نظرات()

LAUNCH! Schoolyard July 6, 2011

Some people get up early to catch fish. I get up early to launch rockets. Sometimes I even catch one.
At 7:30 a.m., Orlando was already humid and HOT!
From ground level I couldn't feel any wind . . .


Here's one last look at the CORKSCREW.
It looked great spiraling during boost with the A3-4t in it's tail.
At ejection the drift was evident and it landed in some body's back yard.
I rarely lose rockets, maybe one out of 100 launches.
Not a big deal losing this one, I've got plenty of spare parts to make another.





The FRANKEN GOBLIN probably got 200' altitude with an A8-3 engine.
After losing the Corkscrew to the winds I made a launch rod adjustment on my camera tripod launcher. Under a spill holed parachute, it landed within 25' feet of the pad. I did catch this one before it hit the ground.




My Powered FLIC had a straight boost with an A10-3t engine to 650' feet. It did drift a bit and hit the basketball court surface hard. One fin was bent on landing but Scotch tape makes it an easy repair.






Here's my Starlight JAYHAWK. The A8-3 boost took it up to 275'.
Recovery looked good until I picked up the model.

The nose cone canard and leading edge of one large fin took a hard hit.
It's not easily repairable, but I'll patch it enough to fly again.


Also flown:
The carded downscale PIGASUS with a Quest MicroMaxx engine. Straight up, nose blow ejection and straight down. Altitude was an estimated 75 feet.

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/16    | توسط: فیروز قوچ داشی    |    | نظرات()

A Tale of Two Saturns Part 1

On a recent trip back home to California I found my old Estes Saturn V. The pictures of the unfinished Estes Saturn were taken in the attic of my Grandparents ranch house in Moss Landing, California.

On the forums, there were questions about the differences between the two versions of the Saturn V kits, the older Estes version and the newer re-issue.
While both the Estes and Centuri Saturn Vs were 1/100th "scale" kits, they were two different models when released in 1969.

The Estes kit (on the left, #691-K-36) had embossed cardstock wraps, the Centuri kit (#KS-10 on the right) had thin plastic vacu-form wraps. The pictures on the right side are from the new Estes Saturn. It uses the old Centuri vacu-form wraps.
















Many "true-scale" enthusiasts complained that the Estes embossed wraps weren't as deep or detailed as they should be on a scale model.

On the other hand, on the Centuri wraps, the vacuform ribs were too thick.

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/15    | توسط: فیروز قوچ داشی    |    | نظرات()

Semroc IRIS Build Part 2 Engine Mount

There is nothing out of the ordinary with the engine mount.
The centering rings are a little thinner than I would have expected, but should work fine.

I wanted to explain a way I use to wrap the retaining tape. This method insures two full wraps around the body tube and over the engine hook.

I use black electrical tape instead of paper masking tape for the engine hook retainer wraps.
It had been posted on TRF that when old engine mounts had been opened up for repairs, that the paper masking tape wraps had deteriorated. Vinyl electrical tape will last much longer.
I don't have any rockets from 30 years ago, but this reasoning seems to make sense. Someone wrote: "Most rockets are stuck in a tree or had drifted away before the masking tape wrap would give out anyway!" Still, I think the black vinyl tape is better than the paper tape. Paper tape tears - did you ever try to tear black electrical tape?

Hold the engine mount with the engine lock (or clip or hook, whatever you want to call it) down.

Start your wrap 1/4 turn above the hook.

Continue over the hook until the tape is on the opposite side.

Do one more complete wrap around, back to this point.

Here's the finish point.

You have made 1 1/2 wraps, going over the engine hook twice.

منبع:
http://modelrocketbuilding.blogspot.com

نوشته شده در تاریخ 1390/04/15    | توسط: فیروز قوچ داشی    |    | نظرات()