Flying Engine Mount Build, Finished

I forgot the launch lug holes!
You won't need a launch lug on this one. Two holes in line through the centering rings is all it takes.

Ideally, the holes should have been punched before the rings were glued on. My rotary punch doesn't allow me to get close enough to the engine mount tube. It'll still slide on the launch rod and launch normally.

The bottom ring was punched. A launch rod was slipped through and turned against the upper ring leaving a mark for the second punch.

Here's how the launch lug fits.
This flying engine mount should be flown with A10-0t or A10-3t engines.
This is a tumble recovery rocket. Call a "Heads Up" before launch.

Altimeter Hole Sizes? TIP

The Estes Altimeter instructions are vague about how big the pressure sampling holes should be.
They show small square holes, very hard to cut with an X-Acto knife.

Perfect Flight makes small "flashing count" altimeters for $25.00 CLICK HERE
From the Firefly PDF instructions here's some more in depth information:

Static Pressure Sampling Holes 

You must drill one or more clean-edged holes in the payload
compartment to allow outside air pressure to be sampled by
the altimeter (see table below for recommended sizes). These holes should be as far away from the nosecone shoulder and other body tube irregularities as possible (at least 3 times the body tube diameter or more) to minimize pressure disturbances being created by turbulent airflow over the body
tube. Sand the area around the hole as necessary to eliminate flashing or raised edges.
Best performance and greatest accuracy will be achieved by using four smaller holes distributed at 90 degree intervals around the body tube’s circumference instead of a single larger hole. When using four holes, each hole should be ½ the size of a single hole as noted in the table. This will minimize the pressure variations due to wind currents perpendicular to the rocket’s direction of travel.

According to the list above, the holes I've been punching in payload tubes have been WAY too large!
These are directions for the Perfect Flight Altimeter, not the Estes Altimeter. There might be a difference in the recommended hole sizes and different brand altimeters - who knows!

Rocketarium Hydra Sandhawk Build Part 13, Vent Hole Drilling

The inside edges will be rough. You'll need to toughen these up to sand off the edges.

A Q-tip was dipped in some medium CA glue and swabbed around the inside of the drilled hole.

Some 400 grit was wrapped around another Q-tip in a cone shape.

Turn the sandpaper in the hole to smooth and "round" it out.

Rocketarium Hydra Sandhawk Build Part 12, Vent Hole Drilling TIP

1/4" diameter vent holes are drilled in the booster side walls.
The instructions say to drill a 1/8" hole first then enlarge it to 1/4".

TIP: You can make a "drill" out of a 1/4" diameter brass tube.
The inside wall of the tube was filed to a sharp edge using a half round file.

This sharp edge works pretty well to cut a 1/4" hole through the tube wall.

Take an extra moment to center the tube before starting to drill.
Spin the tube until you start to scratch the outside layer. Remove it and check to be sure it is centered. If the circle is positioned correctly, continue the drill.
The tube will want to collapse in so go slowly. It's easier to drill a hole when you can apply some finger pressure on the inside tube wall. You can't reach the inside of the BT-60.
After drilling through the outside continue through the interior BT-50 engine tube wall.

Here's how the tube will look after drilling through both sides of both tubes.
We'll clean up and strengthen the edges in the next post.

Mars Snooper Build Part 7 Nose Cone Weight

Jumping ahead to Step 12:

The lead nose weight (Semroc #NCW-1) was slightly wider than the inside diameter of the upper BT-20D tube.
The outside edges of the weight were easily filed down to a smaller diameter.



There is two screw eyes in the parts list. One holds the lead weight high in the BNC-20N nose cone.
You'll have to drill a hole in the center of the weight.

Be sure you are centered. If the hole is off center, the weight won't clear the sides of the BT-20.

I drilled the hole with a older, used #11 blade tip.


Here's the weight in place.
TIP: Note the screw eye isn't all the was into the nose cone.
Sometimes you want to leave one thread of the screw eye exposed beyond the edge of the flat weight.
Go too far in and there won't be any threads to hold the lead weight against the base of the nose cone.

Mars Snooper Build Part 6 Lug Hole Punch

The hole was punched using the largest cut tube my rotary punch, 3/16" diameter which fits the 1/8" launch lug perfectly.

I found I had to widen the hole, my punch might be getting dull.
A sharpened dowel worked great to slightly open the hole.


Here's the first fit of the lug through all three shrouds.

The instructions suggest an LL-2C which was 5" long.
I only had 3" lugs from the Sputnik kits.
At 3" it's just long enough to span through the three shrouds. I'd recommend the longer lug for a little extra room for the angled trimming in Step 10.

TIP: Normally, I would form the shrouds with the printing to the inside.
I don't want to take the chance of the #1, #2 and #3 showing through the paint!
But, there are too many cooling vane gluing lines that would be hard to re-draw on the shroud.
I'll have to take my chances with the printed shroud numbers later.

Batter Up Build Part 2 Drill and Interior Tube

A BT-20 was centered over the end and traced around with a fine point Sharpie pen.








Using a new blade, the interior of the BT-20 diameter circle was removed.

If this circular cut fits the tube well, it should give enough support. There is no way to insert any centering rings inside the body of the bat.





The finger indents actually hug the Bt-20 very well. It made a good friction fit inside the bat handle end.






The front end of the bat was marked and a circle cut like the rear end.

Raisin' Maize Build Part 4 Cleaning Up The Bore

Here's what the tube will look like coming up from the bottom through the top. You can see the cut Styrofoam inside the sharpened brass tube end.






Wrap some 220 grit sandpaper around a BT-5 and remove some of the excess Styrofoam from the inside edge of the upper cut hole.






To give yourself a better gluing area for the nose cap adapter, cut a round hollow into the nose cap. Make the hollow about the diameter of the 5 sized black fish paper adapter.

Raisin' Maize Build Part 3 Reaming the Interior

I don't know if this is how First Flight Hobbies accomplished this. Here's the way I cut a hole for the BT-5 tube.

Get a 1/2" diameter brass tube and file the edge sharp.
If the brass tube wasn't sharpened, the cob drilling would be very difficult.


Push and turn the sharpened brass tube from the nose cap end. Center it as best you can and while turning make sure the tube is going in straight.
Drill about halfway down the inside of the cob
Remove the tube and push out the styrofoam from the brass tube by pushing it out with a dowel.



Turn over the cob. Pull out and discard the tuft of "silk" from the bottom.

Continue reaming the cob from the bottom.
Keep the brass tube straight and try to intersect the hole you made earlier from the top.

Spool Rocket Build Part 6 Lug Hole Drilling

Look closely at the center hole on the bottom CD. You can see where the notch was cut for the engine hook movement.

The launch rod hole was started by spinning the tip of my hobby knife on the disk mark.
After drilling through the other side, the hole diameter was widened with a small diamond file.



Here's the bottom disk after notching for the engine hook and drilling for the launch rod.

It's been set on top of the upper disk to mark the location for the launch rod hole.
The upper CD was then drilled.

Spool Rocket Build Part 4 Drilling The CDs

Center an engine casing on the CD, and trace around it using a fine point permanent marker.

The molded circles on the CD will help with centering the casing.



I tried to enlarge the center hole too quickly and cracked one of the clear CDs. So I pulled two new CDs and started again.

It's easier to enlarge the center hole by cutting at an angle. Flip over the CD and angle cut from the other side.
The picture shows the blade angle, the blade is up and the handle down.

You'll have to continually check with the casing and motor mount tube to be sure you don't make the hole too large.



A small piece of 220 grit around my finger was used to help round out the hole.

Enlarge the center holes on both CDs to a tight outside diameter fit on the motor mount tube.

Estes Saturn V Build Part 51 RCS Nozzle Drill

The instructions suggest using a scribe or sharp pencil to make a gluing hole for the R.C.S. nozzles.

A sharp pencil? Don't try it, you'll never get it through the body tube wall.
I started the hole with a small awl.

The hole diameter was widened by twirling a #11 blade in the hole.

The instructions say the hole should be 1/16" diameter. The gluing pin on the back of the R.C.S. nozzle piece is actually a little smaller than that.




The hole edges were cleaned up with a small diamond rat tail file.

As you are widening the hole, check for a good fit using the pin on the back of the nozzle piece.

Time spent on build: :30
Total time on build so far: 50:00