Viper Mk II HS

[Mike Howie]

This is my first attempt at a build thread, so be gentle. I did have some
problems with my camera on some of the steps. The pics were not in focus.
I hope they're good enough. This rocket will NOT be kitted by me. Some
obvious steps were left out. (I just forgot to take photos of them. ) If
you build this rocket, be sure to check the stability before flying.

Here we go! The Viper Mk II HS (Howie Stretch). I'd Originally built the Viper
Mk II as close to the picture sizes shown on the ZOIG web site. But I put too
much nose weight in, and she coned some on the way up. So this time I
stretched her some.

 

[Mike Howie]

The assembly was done in sub-assemblies, then put all together. Easy part first.

The top Motor assembly:
Parts:
1 BT20 x 3in
2 CR 5020
1 BT50 x 2.75in
1 BT20 x 1.25in
1 Shroud 7.36 x.976 x .875

I used VCT to draw all my shrouds. After printing the shoud, I transfer it to
manila folders. I find them stiffer than paper, but still easy to roll.

Take the BT50, and mark it in 4 90 deg sections. Mark one end 1/4 in all the
way around. This is the front. Mark 2 opposite lines 1/2 in from the front, and 1/2 in from the end. Mark the line around the front 1/8 in down toward
the bottom line,and 1/8 in up to the top line. Connect the front marks down,
and the rear marks up. These are your cutting lines. Insert a spent 24 mm
motor in the BT 50 and using a sharp blade cut along the lines.

 

[Mike Howie]

I hope you can see what it looks like from the blurry photo.
Now take the long BT20, and attach one CR5020 to the very end of the BT20.
(Now known as the front), and the second CR5020, 1in from the rear. Using
CA glue the BT20-CR assembly into the cut BT50, so that the front Centering
ring is even with the rear of 1/4 in ring on front of the cut BT50.

Mark the short BT20 at 180 deg. Draw line the full length of the BT20, these
are sight/guide lines. Glue the short BT20 into the front of the cut BT50.
NOTE: This BT20 is NOT CENTERED. Use the sight lines to make sure the
short BT20 lines up straight with the BT50.

 

[Mike Howie]

After the glue has dried. Glue the shroud onto the front of the motor assembly.
A trick that is use is after transfering the shroud template to the manila folder,
I cut the large arc slightly over size. It makes it easier to slide onto the large
diameter tubes. Then I just sand the extra off.

Sand the front of the assembly at a slight angle. This will cause a gap on the
front of the assembly between the shroud and the short BT20. I used a little
scrap manila paper to fill the gap.

Now I worked of the fin (rudder). I used 3/32 balsa. With the rudder template,
I cut two rudders, then I glued the two rudder halves together, sandwhiching
the template. This makes a FAT FIN. I then sand the fin down, from a fat
front to a thin rear. You can also add the fin details at this time.

 

[Mike Howie]

To finish off the top motor assembly, Glue the rudder along the top of the
Cut BT50 :surprised:

If you do what I did, now you'll set the whole thing aside and build an easy
rocket.

 

[jflis]

looking cool.

As for the focus problem, 2 things will help:

1. More light so that the camera auto focus can *see* what it's doing
2. See if your camera has a "macro mode" for close up photography. Don't use the zoom while in macro mode.

 

[rosko_racer]

Keep those pictures and instructions comming... This is one that I have been thinking of building for a while. Looks great!!!

 

[Blades]

That is one sexy bird, Mike. I may have to build one myself (after I see how you built yours, of course ).

 

[rosko_racer]

The assembly was done in sub-assemblies, then put all together. Easy part first.

The top Motor assembly:
Parts:
1 BT20 x 3in
2 CR 5020
1 BT50 x 2.75in
1 BT20 x 1.25in
1 Shroud 7.36 x.976 x .875

I used VCT to draw all my shrouds. After printing the shoud, I transfer it to
manila folders. I find them stiffer than paper, but still easy to roll.

Take the BT50, and mark it in 4 90 deg sections. Mark one end 1/4 in all the
way around. This is the front. Mark 2 opposite lines 1/2 in from the front, and 1/2 in from the end. Mark the line around the front 1/8 in down toward
the bottom line,and 1/8 in up to the top line. Connect the front marks down,
and the rear marks up. These are your cutting lines. Insert a spent 24 mm
motor in the BT 50 and using a sharp blade cut along the lines.

Boy, I am having a hard time following the instructions. MH, could you make a side view of the BT-50 and shadow/highlight the area to be cut?

Edit: something like the attached pic.

 

[Mike Howie]

I hope this helps. In the photo the motor rolled so you see it from the bottom
3/4.

 

[PunkRocketScience]

Wow! That's an impressive build Mike! I can't wait to see the rest of it!

 

[rosko_racer]

Mike, how did I do?

Here is what I have done so far. On pic one are a few shots to show:

- the forward 1/4" ring and the forward centering ring
- how the end business looks like.
- the front off-centered BT-20,
- the shroud and glued front BT-20.

I used VCP to redo the shroud. I made a longer one. When the tabs dried I cut the bottom to an angle to make it fit easier. Once glued I covered it with CA and sanded the edges. I measured .25" from the top-forward part of the shroud and sanded in an angle to the bottom-forward part of the off-centered BT-20...

The second pic shows the final product... now I await further instructions...

 

[Mike Howie]

Mike, how did I do?

Here is what I have done so far. On pic one are a few shots to show:

- the forward 1/4" ring and the forward centering ring
- how the end business looks like.
- the front off-centered BT-20,
- the shroud and glued front BT-20.

I used VCP to redo the shroud. I made a longer one. When the tabs dried I cut the bottom to an angle to make it fit easier. Once glued I covered it with CA and sanded the edges. I measured .25" from the top-forward part of the shroud and sanded in an angle to the bottom-forward part of the off-centered BT-20...

The second pic shows the final product... now I await further instructions...

Looks real good to me. I just wish all my photos turned out that well.

 

[Mike Howie]

Next up, the Main Motors!
PARTS IS PARTS:
2 BT55 - 1.25 in
2 BT50 - 1.25 in
1 BT50 - 1 in
2 BT20 - 3 in
3 CR5550
2 CR5520 - Hand made. Off center cut.
2 Shrouds - 1.325 x .976 x .4
2 Shrouds - 1.325 x .736 x 2

Oh yeah, I guess I should post the patterns.

 

[Mike Howie]

Lots of parts, and lots of steps

 

[Mike Howie]

One thing to remember as you build the main motors, there is a right and left
motor. I forgot and had to make a new left motor.
Roll the shrouds. I like doing this step first. Gets them out of the way.
Mark the BT20, and the BT55, 180 deg apart, extend the lines the length of
the tube.
Around both ends of the BT55, draw a line 1/4 in from EACH end.
Now pick which BT55 is the right, and which is the left. Make an indicator on
each BT55. While you're at that, pick the top and bottom. (from the 180 deg
length lines).
Glue 1 CR5550 to the very end of the BT50 (1.25)
Glue the BT50/CR5550 into the very end of the BT55.
Mark around one end of the BT20, 1 in from the end\
Glue the off center CR5020 on the 1 inch mark. The short end is the back, and
fits into the BT55.

 

[Mike Howie]

Oh, by the way, if after looking at the photos, you see a way to do the
step that works better for you, go for it. The way I did it was just how I
thought to make it work. There could be easier ways to go.

Facing the BT55/BT50 assembly away from you, and looking at the top,
mark one BT55, 1/8 in from the top line. On the right BT55 it's 1/8 in to the left. On the left BT55 it's 1/8 in to the right. Extend these marks BETWEEN
the marks around the ends of the BT55.

On the Right motor mark 3/8 in to the left.
On the Left motor mark 3/8 in to the right.
Extend these marks between the end marks. You've just marked the Access
Hatch on the motors. (See the second pic).

 

[Mike Howie]

Now with a sharp blade cut out the access hatch.
To make the inside tray, cut the 1 in BT50 into 2 - 3/8 x 1 in strips.
Cut the last CR5550 to fit each end of the strip.
Using a Piece of scrap finish the tray. (See 2nd Pic).
There has to be a better way to get this cutout effect, but with the BT20
going into the other end, I just couldn't think of it. (But I FEEL there is one).
Glue the tray inside the BT55, under the cut out.

Glue the BT20/CR5520 into the front of the BT55. Line up the Bottom line, with
the bottom line on the BT20.
Make sure the two line continue straight!

 

[Mike Howie]

After the Glue dries, it's time for the shrouds to go on.
Using the same steps as in the top motor, glue the front shroud onto the BT20.
I like to line the seam up with the bottom line.
Then glue the back shroud over the BT50.

Just a note: The bottom line is the attachment point to the main body.

You should now have a left and right main motor.

I'm done typing for now, Next up the BODY:surprised:

 

[Mike Howie]

Just realized, I forgot the shrouds.:lol:

View attachment sideback.pdf

View attachment sidefront.pdf

 

[rosko_racer]

Mike: are the shrouds for the lateral engines off centered like the top one?

 

[Mike Howie]

yes, they are off center. But with the longer BT20 the angle isn't as
pronounced.

 

[Mike Howie]

Time for the Body
PARTS IS PARTS:
BT50 13.5in
1/32 Balsa
1/8 Balsa
1 Shroud 1.91 x .976 x .7
1 Shroud 1.91 x .976 x 6

The BSG Viper is not a 'round' rocket. It's more oval. So I made an oval body,
by skinning over 1/8 balsa oval frame. I used 1/32 balsa, with the grain going
in parallel to the body length. Balsa that thin rolled easily.

First print out the graphic "body frame". and transfer to the 1/8 in balsa. You
will also have to cut out the center for the BT50 to fit through.

Mark around the BT50 at 4 3/8 in. again at 5 3/4 in. and lastly at 7 in.
The Marks at 4 3/8 and 7 are the outside of the main body.
Slide the oval 'frame' centering rings onto the BT50 at the 4 3/8 and 7 in marks. Be sure the outer rings are 'inside' (toward the middle) the two outer marks. The rings should all be at right angles to the BT50. Set the body
on a flat surface, on the flat edge of the rings, so the three rings line up
the same.

View attachment bodyback.pdf

View attachment bodyfront.pdf

 

[Mike Howie]

I couldn't get the last pic to fit on the last post.

Your build should look very much like this.

 

[Mike Howie]

This next step isn't as hard as you might think. Skinning the frame.
I only found 4 in 1/32 balsa, so I had to use two pieces. There is 6in out
there somewhere.
I don't want to give an exact measure for how wide the balsa is, because
when I built mine, I needed the 'slop' factor. The length is 4 in.
Put some glue on the 1/8 balsa frame rings, and wrap the 1/32 balsa around
the oval rings. Use some rubber bands to hold the skin on the frame. It's o.k.
that there is over lap when the 1/32 balsa meets at the beginning. I trimmed
to fit after I was done.

 

[Mike Howie]

If you had to use two pieces of 1/32 balsa, try to keep the seams as small as
you can. There will be details going over the seams, so small gaps will be
covered up.

If you can't find 1/32 balsa, you could get by using a thin cardboard, heavy
paper. If you go that route, there won't be any grain to fill.

You now have a nice muffler look assembly.

 

[Mike Howie]

Now for the shrouds, front and back.
You did make the shrouds, didn't you?

 

[Mike Howie]

Putting on the shrouds can take a little time to get right. Line up the shroud so
that the seam is on the side you decided is the 'TOP'. You're trying to put
a round cone, over an oval base. The 'sides' of the body will meet the cone,
but the top and the bottom will want to gap. Gently press down on the top of
the shroud to minimize the gaps. When you glue hold the top and bottom to
close the gaps. After the glue dries, trim the extra paper from the shroud.

Usually at this time I would strengthen the paper shroud by coating it with thin
CA. Hold off doing this for now. There are some details to add yet, and you
will get a better hold, going on plain paper.

 

[Mike Howie]

The part of the Viper under the motors looks, to me, to be square. So I framed
it and made it square.

Cut two strips of the 1/8 balsa 1/8 x 1/8 x 4 3/8 in.
Angle one end to match the angle of the rear shroud.
Glue to the back of the BT50. The strips should be 1/32 SMALLER than the
height of the oval body section.

At this time I started working on my fins. I did the sandwich procedure again.
With the 1/8 balsa glue the template on one piece of balsa, and let dry. Trim
around the pattern, then glue to a second piece of balsa. The pattern is
between the two pieces of balsa. Place under something heavy and smooth
to let dry.

**NOTE: when trimming around the root edge of the fin, I stayed slightly out
of the patterns edge. This way I could sand a better fit on the
Main Motor assembly.

 

[Mike Howie]

OOPS, I drew the pattern wrong .
When you print the 'side' pattern, lop off about an 1/2 in from the corner.
Cut out the 'side' pattern from the 1/32 balsa. On the inside of the curve on
the front, bevel the edge to match the angle of the rear shroud on the main
body.
Glue the sides directly to the body tube.
Now using the 1/32 balsa again cap the top and the bottom. The top and
bottom pieces of balsa should rest on the 1/8 in framers, and meet with the
top of the oval balsa body.

Nice square back