Not Enough Room? TIP

Occasionally you are stuck with a short model without much room for a parachute and wadding.
If you have a plastic nose cone you can use the hollow interior for most of your parachute and shock cord packing.

Cut away most of the shoulder leaving the tie down "lug". Be careful in the corners, don't start a tear in the plastic.

Notice the parachute is not tied to the nose cone lug, but 1/3 the way down the shock cord. This is important.

The shock cord goes in first.
This is what will help pull the parachute from the hollow nose cone.

The chute goes in next, just set it in and on top of the loose shock cord already inside.

When the ejection goes off, the nose cone is ejected.
As the shock cord extends the parachute is pulled out of the nose cone.
With the attachment point 1/3 the way down the shock cord, the parachute will be tugged out of the nose cone.

I did make the Orange (actually a 1" longer Quest Cobalt) for engines larger than an A6-4.
Twelve flights and twelve parachute deploys.

Decal Fix on the Cobalt Orange Part 3

The nose cone decal is harder, you don't have the black lined border to hide the white decal edge under.
Cut an extra decal to size right on the edge of the yellow color.
(This decal is one that got wet and is wrinkled. I was going to toss it, but kept it for a template.)
Trace this onto the white (paint) decal sheet.

Take the width of the pencil line into consideration and cut out the white piece just inside the pencil line.

The two layer decal layed down well on the curved surface. Three raised folds were lightly sliced with a razor blade. The folds were rolled over with a pointed dowel until they held to the surface.

The white underlay cut was close, there is a sliver of white showing on one side, not enough to worry about.

The inset picture shows the model before the white underlay was added.
It's a big improvement.

This white decal technique won't work in every situation. Simple shapes you can cut to size work well. I wouldn't even try to cut out lettering from a painted white decal sheet.

Enlarge the picture to see the wrinkles on the blue Cobalt nose cone sticker. I hate the stickons especially when used on a nose cone. When you think you've got them smooth, come back in an hour and check the raised edges.
The home printed water slide decal on the Orange nose cone has adhered well on all sides of the nose cone. It took some coaxing to get it to lay flat but the end result is much better.

Decal Fix on the Cobalt Orange Part 2

Start with the easiest decals to back up with the white - the black outlined triangles that go on the fins.
That black edge will cover up the edges of the white triangle set down underneath.
I'm cutting one of the extras inside the thick black outline to make a template for the white decal.





Take your template and set it on the dried, white decal sheet.

Cut around the outside of the template. Make four white triangles.

You can discard the template decal, it's to small to be used now.

Cut out the small triangles outside of the border. This gives you a clear edge around the decal which helps hold down the raised decal.
This outside decal will be slightly raised above the surface with the white layer underneath.






The white (paint) decal triangle is applied to the fin. Be sure it is straight, you won't be able to move the background when the printed decal is on top of it.

The inset picture shows the yellow and black ink jet decal over the white.

Decal Fix on the Cobalt Orange Part 1

I wasn't happy with the way the yellow colors showed up on the water slide decals I made for the "Orange" model. The yellow ink was too transparent and when placed over the orange paint the yellow color disappeared!
I read about this technique on one of the forums. I wish I could give credit where credit is due.
If you don't have an Alps printer, here's one way to get a white undercoat on homemade water slide decals.

On the left is the yellow and black ink decal applied to the nose cone of the "Orange" rocket.
To the right is a decal half slid off it's white backing paper. At the top you can see how transparent the light yellow ink is

First, the old decals had to be lifted.
These decals were done about a week ago so they shouldn't be hard to remove. If you haven't done a clear overcoat, sometimes you can lift them with masking tape.
I just wet the decals and lifted a corner with a razor blade. It was pulled up easily in one piece.

For the white background, gloss white paint was sprayed on a new water slide decal sheet. Two coats were applied with full coverage to the edges. A clear coat is not needed, just the white coats.

All you are really doing is making a transferable layer of white paint.
You'll be able to cut the white sheet to most any small shape to go under the yellow and black decals already printed up.
I sprayed white over an entire sheet. Even after this project is done, I'll have some white background material for another build down the road.

I always print up extra decals. I had plenty to make this correction.
Home printed water slide decals can be harder to apply than a silk screened decal from a kit.
Extra prints are handy to have, you might screw up the first tries.

Quest Cobalt Evil Twin - ORANGE!

I built a second Cobalt based model at the same time the stock kit was built.

This one is ORANGE.

I had an extra Quest nose cone and some 40mm body tube.

All is the same except for the body tube length. The Orange tube is 5" long, the Cobalt kit tube is 4".

That extra inch gave me the room for a small parachute. The extra length will also help with stability.

The kit decals were scanned and cleaned up a bit.
A font was picked that worked with the decor.

Notice the yellow areas on the decals.
When these were transferred onto the orange paint, the yellow was invisible!
Not a big deal, It all still works in just the black.

Originally it was going to be called "CORAL" but I didn't have the right color on the shelf. I did have a new can of orange.

Side by side you can see the Orange is slightly taller than the Cobalt.
It's only an inch, but that does give me the room for wadding and a small parachute.

Quest Cobalt Build Finished!

It's a cute little model, should be a good one for the Quest A6-4 engines I have.
I'm looking forward to flying it at the small, schoolyard field.

A little nose weight (a forum post recommended 10 grams) and it might be stable with B6 engines. I probably wouldn't fly it with a C.

The forum comments are right, there is little room for the wadding and streamer if built stock. I did remove most of the nose cone shoulder base and will pack the streamer there. Hopefully it'll pull out of the nose at ejection. More on that in the previous blog post.

The nose cone sticker with the wrinkles at the top.
The stickers look pretty good cut tight, right on the edges.
On the fin stickers, be sure the base is straight when the model is standing up!

Quest Cobalt - Packing the Streamer TIP

I had to be sure the streamer would be pulled out of the nose cone at ejection.
Here's one easy way to get it done -

Set the nose cone tip into the body tube to hold it.
Stuff all the shock cord and some of the Kevlar cord into the nose cone cavity FIRST, before the streamer.

Press the streamer into the nose cone about an inch and a half at a time.

Set the streamer on top of the shock cord and Kevlar already in the front nose end of the nose cone.

The nose cone easily slides into place without the streamer and shock cords in the way.
At ejection, the the shock cords (above the streamer) help pull the streamer out.
Pull out the nose cone to see the streamer is pulled from the nose cone cavity.
Try this a few times to get it right with little resistance.

Quest Cobalt Build Part 7 Step 13-15 Paint and Decals

After the Cobalt was painted an overall white, two opposite fins were masked off.

The top fin has been masked at the root edges with Scotch tape and covered with copy paper.
The bottom fin has been masked at the root edges but the paper covering is yet to be taped on.

Blue spray paint followed.

I cut the edges of the stickers right to the color line. This doesn't leave any clear border areas around the stick on decals.

When applying the stickers, set them down using the blade of your hobby knife.
Your fingerprints might show up through the clear areas if you handle them.

With stick ons, I rub a big bead of water on the rocket surface. Set the sticker right down on the water. You'll be able to reposition the decal if water is used.
If you apply one of these stickers dry, you won't be able to lift it without pulling up paint!

With a drop of water under the sticker you can also press out any air bubbles after the sticker is in the correct, straight position.

Thick, stick on decals don't fit over a curved surface.
Look along the top edge and you can see the wrinkled surface.

Even positioning this decal low, away from the curved nose end didn't help much.

Quest Cobalt Build Part 6 Step 12 Nose Cone Fix?

After reading a few forum comments, it seems there is very little room for wadding and the streamer.
With the nose cone in place, the base of the shoulder is right on top of the engine block!
I'll try to store the streamer inside the nose cone and pack it so the shock cord would pull it out at ejection.

The side of the nose cone shoulder was cut off with a razor saw. I kept most of the support around the shock cord mount loop.

  
I ended up making the vertical cut at an angle to allow and easier pull out of the the streamer.

Notice the corners are rounded.
This makes a stronger, cleaner cut with less chance of tearing.
Sometimes the plastic on a blow molded nose cone can be thin.

Quest Cobalt Build Part 5 Step 10 and 11 Gluing Fins and Lug

The launch lug was glued on and the body tube primed and sanded.
Sometimes its easier to prime the body tube with the fins off.
The fins were primed and sanded before gluing onto the body tube.

Fin lines were marked then those pencil lines were roughed up for better adhesion.




The picture shows the FinTool holding the fins at a 90 degree spacing.

The Cobalt is ready for the first white spray coats.

Quest Cobalt Build Part 4 Step 7 Fin Marking OOPS!

Step 7 has you cut out the tube marking guide.
As normal, wrap it around the tube and mark for the fins.

I don't like cutting up instructions, I transferred the lines onto another piece of paper and cut out the guide.


It was wrapped around the 40mm tube.
IT FIDN'T DIT!
(If you got that, you've heard of Rindercella.)
Sorry, It didn't fit!

The marking guide was short by about 1/2" inch.
I ended up making my own marking guide.

Quest Cobalt Build Part 3 Step 8 Gluing The Engine Mount

I'll do Step 7, marking the fin and lug locations, after the engine mount is in place.
I want to use my FinTool which centers the engine hook between two fins.

There was a problem with the fit of the engine mount.
The centering rings were too small - the mount was loose and slid right through the body tube!
Decision time -
Build up the centering ring diameter for a tighter fit, or
Make the main body tube inside diameter smaller.

I decided to build up the inside diameter of the 4" long, 40 mm tube.
The picture shows where the mount will fit inside the body.
With the mount glued in, the upper centering ring will be 2 1/4" from the rear of the tube.

A single wrap of 110 lb. card stock will be glued inside the tube.
After testing the placement and marking the overlap, the card stock "shim" was 2 1/4" high X (just over) 4 3/4" wide.

To allow a little overlap of the centering ring depth, I cut the height to 2 5/16".

The card stock was glued into the tube.

You can see there is a small overhang out the back of the tube.
After the glue dried, this was sanded off with a block.

With the card stock in the tube, the centering rings needed a little sanding for a friction fit.

I didn't apply a glue bead in the tube and slide the mount into place.
I slid the mount into place and after I was sure both tube ends were flush fillets were applied using a Q-tip.

Quest Cobalt Build Part 2 Engine Mount Steps 1 - 6

I substituted a thicker ST-7 tube for the thin yellow engine mount tube supplied with the kit. The Quest centering rings are a tight fit on the ST-7 tube, so it took a little sanding for a slip fit.

Look close at the tube and you'll see a pencil mark at the center of the tube.
The start of the electrical tape wrap was centered on this line.

The centering rings aren't notched for the engine hook or Kevlar.

My rotary punch was used to cut a small notch for the front ring and a large round slot for the rear ring.

Another small half circle was punched to allow the Kevlar to slip through.



This is the finished mount.
The instructions would have you apply a glue ring on the engine mount tube then slide the rings in place.
It's easier to slide the rings in place, then apply glue fillets

On my mount, the Kevlar loop and square knot are pushed forward and against the forward centering ring.

In the Quest instructions,
The loop of Kevlar is set beneath the tape wrap!
If left this way, at ejection the Kevlar would be pulled forward, pulled hard against the forward ring.

Another point:
You are told to tie two overhand knots to secure the Kevlar.
Two overhand knots makes a "Granny" knot. This knot isn't secure and could slip when pulled.
You should tie a square knot, it won't slip.
For examples of the Square and Granny Knots go: HERE

Quest Cobalt Build Part 1 Parts

A 4FNC rocket?
I always need good models for soccer field launches and I have plenty of A6-4 engines to run through.
There were "gotchas" on this build and some problem solving. Many have had trouble packing the wadding and streamer in such a short body tube.

I built a clone of the Quest Cobalt a while back.

I wasn't happy with the stability and wanted to try the actual Quest kit to see where I messed up!

All the parts -

That 40mm body tube is only 4" long!

The engine mount centering rings are a thicker, stronger stock. Older Quest kits had thin rings. This is a good improvement.

The laser cut fin stock is 3/32" thick.

Some pieces of interest -

The centering rings have no notches cut for the engine hook movement.

There is no hole for the Kevlar line.
The engine hook will be replaced with a spring steel hook.
Below the engine hook is the "Gripper Tab" to attach the streamer to the shock cord.
Self-adhesive sticker decals - oh great!

Quest Cobalt Clone Answers

Last year I built a clone of the new Quest Cobalt kit.
I know - Why build a clone of a available kit?

A few reasons:
1. I had extra Quest PNC40 nose cones and 40mm body tubing at hand.
2. I wanted a good schoolyard rocket for all the A6-4 engines I'd bought.
3. I'm cheap.

I did my best to clone the model from the rendering on the Quest website. Kit instructions weren't posted yet.
Mine went unstable twice using the recommended A6-4 engine.
The rocket was retired.

A few days back, more kit instructions were added to the Quest website, including the Cobalt. See HERE

My clone was close, except for the engine mount.

I used an Odd'l Rockets XLEH (long) engine hook. My engine mount tube was then 1/4" longer than the 2 3/4" tube supplied in the kit.

The above drawing I made shows the engine mount extending 1/4" out the rear of the model.The Quest instructions show the end of the engine tube flush with the end of the 40mm main body tube.

On a rocket this small and stubby, the CG is critical. It would have to be built as shown in the instructions to be stable.
Lesson learned.

Quest Cobalt Clone Build Part 21 FINISHED!

Here's how the streamer was attached to the shock cord. The streamer is only 1" wide.

Usually the snap swivel would be flipped around when using a parachute. But on this model, there will never be enough room for a parachute. I used the swivel this way so when I eventually change out the streamer it''l be easier.

I used two plastic page reinforcements, one on each side.

Here's the finished model, minus the decals. It was built for the Soccer field launches I do about once a week.

It was launched last wee using a Chinese made Quest A6-4 engine. It went unstable after it left the rod. A little clay nose weight will correct that.

Not the fault of Quest, I was building a clone without the instructions. Who knows, I might have recessed the engine mount a quarter of an inch too far. On a model this size that could make all the difference in stability.

Once Quest posts the instructions on their website I'll know what little difference in construction caused the instability.

Quest Cobalt Clone Build Part 20 Engine Mount Gluing

Now that the body paint is finished, the engine mount is glued in place.

Because the body tube is so short, I'll set the mount in the tube dry and add glue afterwards.

This'll give me the chance align the engine hook centered between two fins.

I went ahead and blackened the back of the main tube interior with a Sharpie pen. After gluing the mount in place, the entire end of the model will be black.

From the front end I added the fillet after the mount was dry fitted.

I added glue drop by drop, making the fillet with a rounded dowel. Any excess glue was picked up off the centering ring with a square dowel.

Quest Cobalt Clone Build Part 19 Masking

After spraying the silver on two opposing fins, the model is left to dry.

Never touch a fin to see if it is dry! If you have to check, touch some paint on a covered masked area to check it.

TIP: In the picture, notice how I pull the mask DOWN AND AWAY from the second color painted line. If I were to pull the tape up I might lift and tear the silver painted area.

The mask line running down the root edge of the fin is good, but -

Looking at the rounded leading edge of the fin, the rounded edge is a little ragged. Because I used so many pieces of tape, this was expected.

While the paint is still pliable, you can CAREFULLY push back the silver overcoat edge with your hobby knife.

I'm not cutting off the paint, but pushing it back a bit. Don't cut - just push.

Don't press hard or you could remove some of the blue.

You are simply dressing the edge a little bit. Use the flat edge of the blade and press back the squared edge rounding it off.