Estes Tazz #7282 Background

The new Estes TAZZ is an updated version of the classic Gyroc kit.

The Gyroc (Kit K-24) was a big departure from the standard recovery eject rockets, the first kit to use "helicopter" recovery. Gene Street gets the well deserved design credit.
To see the original instructions: CLICK HERE

http://vintageestesrockets.com says the kit was introduced in 1967. The Semroc clone kit face card claims 1965. The earliest catalog I can find it in is the 1969 Estes catalog. (picture at the left)
I know it was available as a "Free Kit" with a $5.00 order. Maybe it was a giveaway before getting a page in the catalog.
EDIT: See the comments below for a kit number/time frame explanation by Bernard Cawley.

Good luck trying to mask that "barber pole" paint job!

In the early 1970s, the Gyroc was a good first launch of the day. A great rocket to test the wind direction as it didn't drift far.

The original Gyroc kit wasn't what I'd call "perfect". Built as shown in the instructions, the elastic was always left stretched out between launches. You could sew another elastic line through the fins, but I never did. I had floppy flaps! On this clone I did cut notches in the rudder fins so I could release the elastic.
The PRM (adhesive backed paper) hinges would develop cracks if painted.
Ejected engine casings aren't allowed at some club launches.
The new Tazz kit addresses these concerns.

BMS sold a clone kit for a while, today I don't see it listed on the website. These do show up occasionally on Ebay. The BMS kit used the standard ejected 18mm engine casing which released the flaps.

Semroc has introduced a BT-20 based Gyroc with some interesting upgrades. Their re-issue model uses 13mm engines, the engine mount ejects and return via streamer.
Semroc added notches to the "rudder' fins to allow a change of the rubber bands.

My Gyroc clone was assembled from spare parts and the original instructions back in 2014. To review the build: CLICK HERE
To date it has 12 launches and is a bit banged up. Time for an upgrade!

The BIG Fix, Gyroc Elastic, Part 2

The elastic is double knotted on one end. Feed the elastic through the wing flap from the underside until the knot rests against the flap.

Slide the open end through the rudder notch. When the flap is pulled up against the rudder, mark the elastic at the notch.

The second elastic piece is cut using the first one as a guide for the length.
These turned out to be around 1.15" long between attachment points.

Feed the elastic through the wing flap hole again.

Tie a knot at the mark made earlier.

Slide the end knot of the elastic through notch in the rudder. Notice there is enough of the loose end to each grab it with fingers.







Loaded with an A8-3, Ready for launch this weekend!

Between flights, remove the elastic from the rudder notch.

The BIG Fix, Gyroc Elastic, Part 1

Semroc (ERockets.biz) has brought back the Estes Gyroc. The reissue kit has a 13mm engine mount with streamer attached. The big change is replaceable elastic on the fin flaps.
Balsa Machining Service (BMS) also sells a Gyroc clone kit that uses standard 18mm engines. The BMS kit has the original elastic ties on the flaps.

The illustration to the left (From the ERockets website) shows two notches on the rear of the flaps. A rubber band is set into the notches and over the rudder fins on the wings. This arrangement allows changing the rubber band if it looses elasticity.

The problem with the original Gyroc has always been the weakening (over time) of the flap pull elastic. Even with an engine out of the model the elastic is still under tension. Here's a simple solution allowing removal of the elastic between flights and a change if the elastic stretches out.


Here's my Gyroc with the stretched out elastic. The elastic is weak and doesn't pull the flap up to the rudder fins.

On the right is the elastic looped through the rudder hole. This hole will be cut through to the leading edge making a notch.


The old elastic was cut off.
Using a thin razor saw, a narrow notch was cut into the rudder fin from the leading edge down to the original hole.

The hole on the flap fin was cleaned out (but not enlarged) with a small rat tail jewelers file.

More in next post - 

Estes Gyroc Finished

This build was a bit frustrating but brought back a lot of memories.
The elastic tie positions from the Estes instructions didn't give enough pull so they had to be moved.
Look close to be sure you have covered every area when painting this one.
The fins look straight from all sides but the Gyroc wants to do a slow spiral during boost.
This model was designed before "shotgun ejections". There is a loud POP when the engine ejects.

This one is a fun build using spare parts and some 1/16" thick balsa.
Or just get the BMS clone kit, at $10 it's a great buy!

Estes Gyroc Build Part 11, Elastic

After this step I remembered having the same problems with my first Gyroc build in the 1970s. There was a lot of tweaking to get the elastic to fully pull the flap against the rudder fin stops.

Enlarge the picture an you'll see where the instructions recommend setting the elastic holes. I marked the hole positions with a pencil dot.

The holes were made with a needle before threading the elastic.
TIP: Find the thinnest needle that you can still thread the elastic through. You want the hole to stay small!
The lower hole (near the hinge) didn't give enough pull on the flap. I had to go higher on the flap.
Now I'm stuck with an extra hole on the flap - Oh well!

Behind the flap is a double overhand knot. Over the rudder fin the elastic is looped and sewn through a second time.

The flap had to be trimmed at the root edge (Below the "A" in EXPERIMENTAL) so it couldn't bind when pulled open by the elastic.
If I were to build another Gyroc, I'd make the root edge of the flap a hair shorter so it couldn't rub against the body tube.
EDIT: Check the previous post for corrections I should have made!

When the elastic is tight enough the flap should lightly "click" against the rudder when released.

When all is right, put a small drop of white glue at the thread holes.
TIP: Never use CA (Super Glue) on shroud lines, shock cords or the elastic used here. The CA glue will run up the lines and harden it.

The white glue helps hold the elastic knot tight. Use just enough to hold it but also allow replacement of the elastic if needed later on.

Gyroc Part 7 Post Corrections!

There was reasons I had trouble with the Gyroc flaps!
My Gyroc flaps needed trimming to clear the body tube when flipped.

I'm the type that follows instructions.
Didn't G. Harry Stine say: "When all else fails, try following the instructions!"
I had built a Gyroc years ago, maybe I thought I was past following the directions.

I try to keep up on the comments from blog readers and respond to questions.
"Anonymous" made comments on the Gyroc, Part 7 post from December 23 -
He was right in his observations. This one deserved answers and a blog post.
"Anonymous'" comments are in Italic

Actually, instructions call it "fin-flap" assembly, not "flip-flap".
You are right! That's what a tired dyslexic gets for trying to read directions at 2 a.m.!


"Noticed that you matched up the flap root edge with the fin and left that portion of the edge square. If I'm not mistaken, there was supposed to be a slight gap between the flap root edge and the body tube (if you take the parts templates from the pattern sheet and lay them out, you'll find out that the flap is slightly shorter than the fin. Also the instructions show the root edge of the flap portion to be rounded rather than left square). Although having the flap root edge seating tightly against the body tube might give a cleaner appearance, you'll probably run the risk of the flap binding against the body tube - especially after primer and paint."

That's what happened!

Putting the two pattern sides together I saw the slight gap at the root edge. If I didn't sand the root and outside edges even with each other, the fin flaps would have worked without trimming later on.

This didn't help much!

I cut the the pattern with the outside edge of the flap (on left) a hair wide. 

When I stacked the two fin pieces I gang sanded them to match up the root and outside edges.

Step 5 illustration shows the upper fin half slightly wider than the lower half. It's subtle, but it is there. I didn't notice it. 

"As far as the positioning of the fin-flap assembly -- I'd interpreted the general layout illustration to indicate that the hold-down tabs should be attached to the flap near the "corner" at the root edge of the flap (where it flares out), and that the forward edge of these hold-down tabs would need to be set back far enough to clear the rear edge of the body tube, but not so far back that the hold-down tabs would protrude below the rear edge of the engine when it is inserted. This pretty much ends up determining the location of the fin-flap assemblies."

That's where they ended up. I wish the instructions went into more detail. The drawings were smaller and confusing. You'd think I would know how to do this by now!

Anonymous - thanks for the comments, I appreciate the feedback. 
Let me know if anything I write raises questions.

Estes Gyroc Build Part 10, Paint and Decals

Here's the Gyroc after the first white undercoat.
This is a tough model to spray and even harder to sand smooth. There is just too many inside angles to cover!

On the left shows after wet sanding with 400 grit. The nose cone / body tube seam is gone.

There was still some small "sand-thrus" into the gray primer. Sometimes you can touch up the undercoat. The Rusto 2x paint melds into itself pretty well and saves you from spraying again.

I sprayed a small amount into a disposable cup and touched up any gray.
The picture shows more paint on the brush than I would normally use to touch-up.

Here's the Gyroc after the Yellow sprays.

The black decals are applied. It looks close to the 1970s catalog picture.

The elastic ties are next.

Estes Gyroc Build Part 9, Hold Down Tabs

Whoops! I primered the model before gluing on the hold down tabs!
This is right up there with forgetting the launch lugs and not noticing until you go to slide the rocket down the rod.

The instructions didn't make much sense back in the 1970s or now.
Looking back to my first try at the Gyroc, I probably glued them on upside down. I thought the tabs were used to friction fit against the engine - not so.
With the tabs in "neutral position" (the flaps held straight down) the tabs fit on either side of the round engine casing.

I sanded away the primer to open up the balsa for a strong glue bond.

Notice the flat side of the tab is up, the angled inside edge is down.

Look close and you can see how the tab sits beside the curve of the engine casing.

The inset picture shows the tab sicking out a bit from the edge of the flip-flap.

Estes Gyroc Build Part 8, Gluing the Rudders

When setting the rudders, raise the flap to be sure it makes contact on the trailing edge of the rudder.
Again, don't use much glue. Lightly tack the rudder in place, you'll probably be adjusting it later on.

Here the rudder was glued with it's root edge right beside the pencil line from the last step.

The placement of the rudders facing the raised flaps is more critical than the opposite rudder. Glue the flap facing rudders first, then glue up the rudders on the other side.

From the side, be sure the rudder leading edge tips are in line with each other.

From the back, be sure the rudders are in a good cruciform shape.

Everything got white glue fillets, then a final fillet of Titebond M&TG.






The 90 degree angle is too tight for your finger.

I used a Q-tip to smooth the fillet in the root edge areas.

Estes Gyroc Build Part 7, Gluing the Flip-Flap

Before going any further, read this post regarding corrections to this step:
HERE

Things get vague in Step 6 of the old Estes instructions.
They don't specify how far up to glue the "flip-flap".
(Really, they called it a flip-flap!)

You've got to allow for the friction tab and the drawing does show the root edge hanging over the body tube end.
I set the tab on the fin side and guessed!
The instructions don't say where to apply the glue. I have to wonder how many of these were built with the root edge of the flap glued to the body tube.
On the right side of the picture I've folded the flap and will only apply glue to the root edge above the fold line.

More vague instructions:
The launch lug is trimmed and glued to the line between the flip flop fins. How high? Who knows!
I guessed after looking at the pictures and set it 1" from the end of the body tube.

With the flap taped down the main fins are glued on their pencil lines.

Because the fins are large - 
You are best off using the double glue method and not much glue.
Get the large fins to tack in place, be sure they are straight then add white glue fillets.

Considering when this kit came out, I thought the next step was pretty clever.
The width of the tube marking guide is used to set the rudders.
Instead of holding the marking guide and gluing the fins on, I decided to use the side of the marking guide to draw a gluing line with a pencil.

For an even better alignment, the back of the marking guide was cut off at the same angle as the fold of the fin.

Estes Gyroc Build Part 6, Wing Hinges

Tape the two halves of the wing together. Line up the root edges on a straightedge.
The two wings flip in opposite directions, but tape both wings facing the same way.
When the wings are set on opposite sides of the body tube they will flip correctly.






Before setting down the sticky hinges, wipe down the hinge area.
You don't want any sanding dust, the tape won't stick very well to sawdust.

The center of the hinge strip was marked with pencil. These marks will go right over the joint.

Don't set the hinge down with your fingers. Any oil or dust will diminish the stickiness of the hinge.

Burnish the hinge with the end of a Q-tip.
The Q-tip won't scar or dent the balsa.

Remove the masking tape from the other side of the hinge.
Make sure the two flat edges are even then fold it over and make a sharp crease.

Estes Gyroc Build Part 5, Nose Cone and Lug Prep

The nose cone and body tube joint were already filled with CWF.
The nose cone is rounded and blunt for a good reason, the rocket lands nose first.
The nose cone was toughened up with a coat of medium CA.
After it dried it was smoothed over with 400 grit.




In an optional step you can trim the launch lug ends. The instructions say: "Trim if desired"
The angle cuts on the instructions were extended with a pencil line.
The lug was set over the instructions and the cuts made with a new razor blade. Try not to crush the lug when cutting the end angles.

Sand the cut ends with 400 grit on a block.

When you sand a lug ends the outside Mylar skin will roll over.
Pick it out of the lug with a toothpick and sand it off.

Estes Gyroc Build Part 4, Balsa Truing and Filling

Edit: Don't sand the root and outside edges even like I did! The flap (lower fin) is not as wide as the upper fin. Line up the outside edges and the root of the rear flap fin will be raised to clear the body tube so they can flip!
See this correction post HERE

After gang sanding the like parts the root and outside edges didn't match up. The fin set on the left is before sanding and evening up the sides.
On the right is the large fin pieces, taped together and after sanding.

The fin edges were sanded flat on a block with 220 grit sandpaper.

The fin stock is 1/16" thick. You don't see 1/16" thick fins on models anymore.
Some forum posts have talked about balsa warping when the applied CWF dries.
The balsa will warp down the grain lines when only one side of the fin is drying. When the other side is painted the drying filler counteracts the warp and the fin should end up flat.

Just to be sure, I set the fins in a heavy book when the filler is about half dried.
This is a side view of the root edge of the four wing pieces.
All are flat and straight.

Estes Gyroc Build Part 3, Hinge Cutting and Prep

The tape hinge material is "pressure sensitive" paper.
It's just sticky paper with a removable backing.

I'll cut them from the left over borders from a CD label.


Some extras were cut, I always make extras.







The nose cone will be glued in place and the joint seam filled.
I went ahead and sanded the shoulder to better match the body tube diameter.


All the leading and trailing edges of the fins were rounded.
The straight sides at the hinge were left square.

Estes Gyroc Build Part 2, Cutting the Parts

The Fins (2) Flaps (2) and Rudders (4) were cut from 1/16" balsa stock.
This was old school, tracing around the templates on the balsa with a pencil.

All were cut out with a sharp blade and straight edge.
Because these were hand cut, like fins were gang sanded with a block.

The hardwood tabs (called "Flap Holders" on the pattern sheet) were carved from a larger craft stick.

Pencil lines were extended outside the pattern.
Cut the stick width first.

Next, round the ends.
Cut the tabs to size last.

Estes Gyroc Build Part 1, Parts

Here's a build by request, the Estes Gyroc, # K-24
I received my first Gyroc as a Free Kit for placing a $5.00 Estes order.

Wayne Hill's Rocketry Blog gave some history:
http://rocketry.wordpress.com/2006/06/06/rocket-of-the-week-662006/
"The Gyroc was originally released in 1965 and was offered as “Free with a $5.00 order” in the 1967 Estes MRN. The kit was listed as K-24 and was offered through 1983."

Years ago my first launch experience with the Gyroc wasn't successful.
The moment it left the launcher the fin panels flipped. I didn't install the hold-down tabs correctly. The Gyroc did a tight loop and stuck itself into the dirt. I'm hoping for better luck this time.

On the upper left you see how it appeared in the 1969 Estes Catalog.
As far as I know, this was one of the first helicopter kits available.
I won't be attempting this paint job. It would be tough to get the spiral paint patter under the large wing fin.
In later catalogs the Gyroc was painted yellow overall and used some of the black decals from the Beta kit.

The parts from left to right:
The "Tape Hinge" material will be cut from the border pieces left from a stick on CD label.
The "Flap Holders" will be carved from a larger craft stick.
An LL-2A launch lug, 1 1/4" long
BT-20D body tube, 6 1/2" long
BNC-20B nose cone
EB-20B engine block
1/16" thick balsa sheet (once known as BFS-20)
Instructions printed from the JimZ website
http://www.spacemodeling.org/JimZ/estes/k-24.pdf
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