Quest Magnum Sport Loader #3012 Build, Part 19, Altimeter and Nose Cone Tie

I glue my shock cords in the tri-fold mounts at an angle.
For the explanation: CLICK HERE

I don't use tri-fold mounts often but they can come in handy if there is nowhere to tie down the shock cord.
The idea is to not lose the nose cone and altimeter at ejection. We've all lost nose cones off payload sections.
A short length of shock cord gets a tri-fold mount on each end.
A loop knot is tied in the center to attach the altimeter.

Here's how the retainer cord glued in at both ends. Even if the nose cone came off at ejection, the altimeter and nose cone remain attached to the model.

To mark for the altimeter holes, I did a paper wrap then folded it into thirds. For altimeter holes the spacing it doesn't have to be perfect.
Three holes were made with the rotary punch.

I thought I went deep enough to clear the coupler but when the nose cone was inserted, the coupler blocked the holes I just punched! Oh well . . .

I ended up punching holes in the nose cone shoulder that matched the holes in the payload tube.

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!

Estes Altimeter

I finally bought an altimeter!
All my posted altitudes were guesses based on Open Rocket and Semroc predictions.
I'm a little wary about using it. I know the actual heights reached will be lower than I hoped.

You'll definitely need a small Phillips jewelers screwdriver to open the battery compartment.
It's a good thing the screw stays attached on the lid. If you dropped it, it'd be gone!

There's a interesting attachment clip included.
You aren't told how to clip it on. There are two latches, on the side and ion the middle crossbrace.

I did the vacuum or "suck" test.
The altimeter was turned on and slid into the payload tube.
The holes were covered and my mouth set over the open end of the tube.
I breathed in quickly and checked the reading. 1,539 feet!
We'll see how it does in actual flight testing.

Estes Altimeter Holes Part 2

Again - the Rotary Punch!
The holes will be somewhat hidden in the rectangular decals on the payload section.
While Estes recommends the holes be 2" down from the top of the body tube mine ended up at the end of the rotary punch reach, about 1 3/8" from the top.
The holes are still clear and not covered by the nose cone shoulder.

The Jolly Logic instructions say the holes should be as far forward as possible without being blocked by the nose cone.
This hole placement is a compromise between the two.

The decal edges were already sealed with Future acrylic applied with a Q-tip.
The punched holes got sealed again with some Future.

The inset shows the completed altimeter hole punches.





One last touch -
There was a bit of yellow paint showing at the top sides of the punch.
A permanent marker blackened just the top of the round punch.

Estes Altimeter Holes Part 1

Before punching holes in a body tube for the altimeter, I checked the instructions for three altimeters - The Estes Altimeter and the older and newer Jolly Logic One

Installation Tips:
Altimeter One (OLD)
“We advise that you punch at least three 1/16" to 1/8" diameter holes evenly spaced around the payload bay or the fuselage as close to the nosecone as possible, but low enough not to be blocked by the nosecone once it is inserted.”

Altimeter One (NEW)
“Add a few holes to allow air to escape at altitude.
The larger the airspace in your model, the larger the holes should be."

Estes Altimeter
". . . it is necessary to create 3 to 4 evenly spaced 1/8 inch square or round holes, approximately 2 inches below the open end of the body tube or payload section of your rocket. Cut holes using a hobby knife or 1/8 inch drill."

I knew I couldn't get three or four consistent square holes using an X-Acto knife. How many times has the knife cut farther than you would have liked when cutting a simple engine hook slit?
Cutting 1/8" squares would mean 12 or 16 small straight cuts! That's a ruined tube just waiting to happen.
I could spin the knife tip drilling a round hole. That works pretty well for smaller holes but when the diameter gets larger it's hard to keep the hole round. Drilling with a knife tip could chip the paint.
I'll just punch them.