Wednesday, April 10, 2013

Taking a Look at the New AeroTech DMS H135W-14A Single-Use Motor

Thought I might share a look at one of the new motors in the AeroTech Pro-SU DMS (Disposable Motor System) line of single-use motors with adjustable delays. The motors ship with a long delay that can be adjusted down to the needed delay with the new Pro-SU DMS Universal Delay Drilling Tool.

The first available in the series is the H135W-14A, a White Lightning motor with an adjustable 14-second max delay, which is shipped in a cardboard tube with motor specs and a thrust curve on the side.

Here we read:

Total Impulse: 226 N-sec
Burn Time: 1.7 Sec.
Peak Thrust: 34 lbs (152 N)
Delay Time: 14 sec max (adjustable)
Propellant Weight: 121 grams (4.27 oz.)
Loaded Weight: 211 Grams (7.44 oz.)

Removing the cap from the end of the shipping tube reveals the motor, igniter/initiator, instructions and ejection charge sealed in an anti-static bag as well as a (bottom, L-to-R) thrust ring, which you can CA to the aft end of the motor, the ejection charge cap, and the igniter holder/nozzle cap. 

The initial shipment of these H motors contained the wrong size nozzle cap, but AeroTech was quick to fix the problem, and all our stock has the correct size nozzle caps.

Opening the anti-static bag, here we see the instructions wrapped around the motor, as well as rubber bands that you can use to help retain the igniter before you put the cap on, and the Igniter and BP ejection charge packaged in a plastic bag.

The motor is made of a filament-wound fiberglass casing, with a phenolic nozzle potted into the business end, and a new molded plastic ejection charge holder in the forward end.  The Igniter is a long FirstFire with lots of pyrogen on the tip. The BP for ejection is packaged like in the reloadable RMS motors.

A look at the nozzle end.

A look at the new plastic ejection well.

 The included thrust ring can be glued to the aft end of the casing and fits snugly. Some good CA or epoxy should do nicely here.

 The Universal Delay Drilling Tool is used to drill the delay down to the required length in two second increments.  The tool, like the two other tools for the RMS motors that are available use a 1/16" washer to space for certain 2-second increments.  A 1/32" washer could be substituted if necessary for even finer control in 1-second increments.

 The ejection charge is added and the ejection charge cap is inserted to keep the charge in place. This completes the prep of the motor.  Add your igniter and nozzle cap at the pad and fly!

Before the days of reloads, single-use motors were the norm in high-power rocketry. Reloads are fun for the "fiddle factor", which I enjoy immensely. It is the construction of a reload that puts some "rocket science" in my hobby and is something I enjoy greatly.  However there are times you just want to stick a motor in and fly, and the Pro-SU DMS series will be great for that.  Just remember you pay a little more to have someone else assemble the guts of the motor for you.  This would also be a great motor for level 1 certifications, as it will take away some of  the prep you would have to worry about with a reload.

Other similar motors in the Pro-SU   DMS line under development now available include a 38mm I140W-14A and J270W-14A,  These motors are perfect for Level 1 & 2 certifications and general sport flying and will also be priced competitively with similar reloads.

The H135W-14A Pro-SU DMS motor is available today at the Sirius Rocketry Online Store.

* The AeroTech Pro SU name has been changed to DMS (Disposable Motor System). By any other name it is a high-power single-use motor.