Hydra Sanhawk?

Ed Brown posted this picture on the Facebook Model Rocketry Fanatics page:


So . . .
Is it a HYDRA SANDHAWK or,
HYDRA SANHAWK?

To see the entire build from Finish to Start: CLICK HERE


Here's another face card misspelling:
The Fliskits MECURY REDSTONE

I'm not making fun of these mistakes. I worked in a print shop for years! These things happen. At a glance, it reads correctly. Your mind can fill in a missing letter.
If you've printed up one thousand full color face cards on heavy gloss stock, it'd be a shame to throw them away over a spelling error.

Hydra Sandhawk Ebay Auction Ending -

Bidding finishes up Wednesday night (tonight) at around 10:00 p.m.
No bids yet! This is a BT-60 based two stage model.
Stop by and support the blog: CLICK HERE

New Ebay Auction - Hydra Sandhawk

The two stage Rocketarium

HYDRA SANDHAWK

is up for auction on Ebay

This is an interesting two stage model. The booster takes a 24mm D engine, the upper stage uses an 18mm engine.

A lot of time went into masking the flames on the nose cone. Original pictures were sized to the BT-60 body tube so the flame pattern would be accurate.

The larger upper stage fins are wedge tapered.

Bidding price starts at less than half of the retail price.

To see the model or make a bid: CLICK HERE

Rocketarium Hydra Sandhawk Finished

I was happy with the build and look of the finished Hydra Sandhawk.
This BT-60 based model is tall and impressive.
The nose cone mask was a challenge but turned out well.

The staging on this one is different with a 24mm D in the booster and a 18mm engine in the sustainer.
The small booster fins require almost one ounce of clay in the nose cone for stability.

I didn't care for the supplied peel and stick decals. When set in place the gray boltheads were almost translucent. These decals weren't difficult to draw up and print at home.
This kit did have some masking and paint challenges, as most scale models do.
Down the road I'd like to try a build of the Rocketarium Jayhawk.

Rocketarium Hydra Sandhawk Build Part 23, Decals

I glued the card stock pieces on after painting so they aren't sealed.
I applied two coats of Future acylic with a Q-tip.

The bolt decals I made are water slide and I didn't want the card stock to swell up.

I cut the booster decals width short on one side. The width of the clear backing was cut this way on all the decals.
This gave me a spacing reference when the clear coat was set right next to the attachment piece.

I knew the booster decals weren't applied on top of the fin attachment pieces, but to the side.
I started setting them down on the wrong side! I didn't realize they went near the root edge of the fin and not on the body tube.

Here's how they should have been applied - 
Enlarge the picture and look for the bolt heads on the gold fin root edge.

Rocketarium Hydra Sandhawk Build Part 22, Booster Fin Attachment Pieces

Here's the mask for the booster fins.
They are sprayed gold.

The fin attachment plates on the booster are narrower than on the sustainer.

Scrape away the paint and glue in place with white glue.

A band of aluminum trim Monokote was applied to the top and rear.

At the rear do a rough trim with a sharp blade and any remaining can be sanded off even with the end of the tube.

Here's how the model looks before the decals are applied.

The booster fin attachment plates will be brush painted gold.

Rocketarium Hydra Sandhawk Build Part 21, Fin Attachment Pieces

The instructions give you two choices to make a double layer of card stock for the fin mounting attachments.
I simply glued the back and folded over the card. I dried flat in a book.
You could cut out sixteen pieces then glue and stack them. Folding, gluing and cutting seemed easier.

I set the double thickness card stock piece next to the root edge to mark the gold area for paint removal.
A smaller area than the attachment piece was scraped away down to the body tube.

Each fin attachment piece was pressed against the Sharpie barrel to put a slight curve in it.
This will better fit the curvature off the body tube.

The fin attachment pieces were attached with white glue.
There is no paint on the upper stage fin attachment pieces, they are white on the finished model. I might "seal" the faces of the pieces with some white glue applied with a Q-tip.

Gluing the attachment pieces on after the gold paint is applied gives a sharp color separation, better than you might get by complex masking.

Rocketarium Hydra Sandhawk Build Part 19, Gold Mask and Paint

The fin mounting attachments would normally be glued on before painting. It would be very hard to mask around the attachments.

I'll simply glue them on after the gold is sprayed.

Here's the mask for the gold.

I'm using a Q-tip again to soft burnish the Scotch tape masks along the root edges.

The tan plastic wrap are cut up grocery bags.





The first try was an old can of gold Krylon.
I had bad masks on half of the taped edges. It didn't release at the tape edge like the Rustoleum 2X I was used to. The paint seemed to rip and pull as the tape was pulled up.

I had to sand off the ridge and respray with a new can of Rustoleum 2X gold. This second try gave me a much better clean line.

Rocketarium Hydra Sandhawk Build Part 8, Booster Fin Shaping

The small booster fins are rectangular.
Use your engineer's angle to get them to a 90 degree angle.

After one fin is square, use that one as a template for the other three.
Stack the fins and sand to the shape of the first "true angle" fin.

With all four fins stacked and sanded together try to get all the corners straight.

Rocketarium Hydra Sandhawk Build Part 7, Fin Pattern Transfer

Newer versions of this kit have pre-cut fins. This kit had templates and sheet balsa to cut out.
I'm going old school on this one.
To keep your templates intact after the build you can scan them or transfer the fin pattern with a needle.
Punch the needle through all the corners. I'm transferring the fin pattern to another piece of 110 lb. card stock.

Simply connect the pin holes with a straightedge and sharp pencil.
Cut out the copy and trace onto the balsa stock.

Plan ahead when laying out the fins, there's not much extra balsa!

The kit balsa is very hard and took some work to cut out.

Rocketarium Hydra Sandhawk Build Part 6, Parachute

The parachute gives the option of sizing it yourself.
You can pick from 15", 12" and 9" sizes.

The printed instructions are in the inset picture.

I wasn't sure about the reinforcement disks at first.
I had some trouble separating them from the backing paper.
I ended up using a knife blade tip to remove them. Simply bending the backing didn't release the rings.

They are clear plastic, more like a disk of Scotch tape, plenty strong when in place.

You'll need a card stock backing to punch holes through the flexible parachute material.

You cut the three (doubled) shroud lines to length.

Rocketarium Hydra Sandhawk Build Part 5, Nose Cone Prep

The supplied nose cone clay weighed in at almost one ounce.

A hole is drilled into the back of the nose cone base to install the clay weight. It should be large enough to push in the clay.

TIP: The instructions say to use small balls of clay instead of rolling clay worms. This is a great idea. 
Make small pea-sized balls of clay and drop them in the hole. The small balls of clay will fall more evenly towards the interior tip. Think of crushed ice falling into a cup, more gaps are filled. Pressing the small balls of clay with a dowel is easier than chasing around clay worms inside the nose cone.

The raised seams were sanded down.
My medium CA fill wouldn't stay in the concave seams.
The nose cone was made of HDPE plastic.
You are told to sand the plastic so the primer and paint will stick better.

I may have to use some automotive spot putty for these seams.

Rocketarium Hydra Sandhawk Build Part 4, Booster Engine Mount

The instructions have you apply a line of glue inside the booster tube, then slide the engine block into place using an engine casing.
I prefer to dry slide it into position and tape the casing in the end at the 1/8" mark.

The engine block is filleted from the top using the end of a rounded dowel. Let dry before the next step.

Before punching the engine hook slot, poke just the tip of the blade so you are sure you are right under the glued in engine block.

The engine hook ends were sharp and cut at an angle.
The ends were cleaned up with a metal file.

Instead of gluing the ring right above the engine hook, I notched the upper ring so it fit over the engine hook.
This moved the upper ring to a slightly lower position. The upper end of the hook is now locked under the centering ring.

Rocketarium Hydra Sandhawk Build Part 3, Sustainer Engine Mount

While the kit has a tri-fold mount, I'm switching out to Kevlar.
A small notch was filed in the upper centering ring for the line to pass through.

The forward ring is flush with the end of the body tube.

A ring of glue was applied and the ring pressed in place using my flat sanding block to insure it was flat and even.

A few of the tube cuts were a little rough.
Check all the tube ends and sand flat with your block if needed.

Here's the finished sustainer mount with the Kevlar line in place.

Rocketarium Hydra Sandhawk Build Part 2, Sustainer Engine Mount

I sanded off the brown from the flat surfaces of the centering rings.
Don't sand the edges! The fit in the BT-60 tubes is pretty good.

There's a small "gotcha" in the instructions.
Wait to do the tape wrap until the rear ring is 1 1/2" from the rear.
The tape moves from the center of the tube to the forward end in the same step.




TIP: If your ruler markings are flush with the end - 
Use it to check the ring placement length from the tube edge. Here I'm checking the 1 1/2" distance.
The square end of the ruler will help square up the centering ring so it is 90 degrees to the line of the tube.
Place your ruler end at a few locations around the centering ring as the glue is setting up.

Rocketarium Hydra Sandhawk Build Part 1, Parts

A while back, Rocketarium came out with a LOT of scale kits!
Most are BT-60 based kits and feature a new ogive plastic nose cone.

Parts are of good quality:
Centering rings are laser cut plywood
The balsa fins stock is hard and stiff. (Newer kits have pre-cut fins)

Parts of interest: (clockwise from left)
Large tri-fold shock cord mount
Clay weight
Plastic nose cone
Adjustable size parachute, 15", 12' and 9". 1 mil, red ink over clear
Two wide spring steel engine hooks
Fin attachment stickers (I'll redraw and make water slide decals)
Fin Mounting Attachments (cardstock)
Fin Patterns (Center)


The instructions lack an exploded drawing.
David Stribling drew it up HERE
Check out the PDF link in the first post.
Other posts answer questions about paint patterns.

This was an early edition of the kit with fins you cut out yourself. The kit now includes pre-cut fins.
My instructions were only four pages long with limited illustrations. The instructions have now been expanded and improved. Online I found six pages of instructions with more illustrations.

http://www.allrocketengines.ca/docs/RK-HYDRA.pdf