Aerotech 38mm HP SU DMS Motor - J425R-14A

Don't panic! We're here to help you.

1. First off, take a look at your kit. Are there recommendations on the packaging?
2. If you purchased the kit from us, or if you purchased a kit that we also sell, take a look at the recommendations on the kit's page. It's near the bottom.
3. If your field is limited and surrounded by trees and buildings, choose a motor with a lower letter and number to limit altitude and increase your chance of recovery.

If you're still unsure about which motor to use, don't hesitate to call us at 719-535-9335 and ask for our recommendations. We're warm and friendly, and don't bite (that's a promise).

High power motors are motors that are "H" or above or have an average thrust over 80 N. If the number after the letter, is over 80, it is considered high-power. An H339, F120, G81, and H59 are all considered high-power. A G80 or F43 are not.  

Level 1: H and I motors
Level 2: J. K, and L motors
Level 3: M and above

In order to fly a high-power motor, you must be Level 1, Level 2, or Level 3 certified by Tripoli or NAR. You may purchase a single motor to attempt each certification, just let us know your club membership id and your attempt date. You can only buy the attempt motor for the level you are currently attempting - for example, if you are going for an Level 1 attempt, you cannot buy motors for your Level 2 until you have completed your Level 1 certitication.

The DMS motors feature a filament-wound fiberglass casing, a glass-reinforced composite phenolic nozzle, and a molded plastic bulkhead. All DMS motors ship with a FirstFire™ or FirstFire Jr.™ starter, and all but the H13 include an integral thrust ring. Thrust rings on DMS motors are designed to fit standard motor retainers.

For DMS motors with delays (so not -P) may be shortened using AeroTech’s Universal Delay Drilling Tool™. This does not apply to (P) Plugged motors, which have no delay and require electronics to deploy your recovery device. See the "Related" box above to add the item to your order.

Motor performance data including a sample time-thrust curve are printed on the motor label.

DMS motors are packaged in a distinctive yellow shipping tube with AeroTech logos printed on the outer spiral wrapping, and the same motor label applied to the outside of the tube for easy identification and performance evaluation by the flyer. Caps on the ends of the tube are applied externally and are easy to remove.

DMS motors are different from previous and existing reloadable and single-use motors in the following important ways:

• No hardware to buy, load, clean or lose
• High strength, lightweight molded phenolic or filament-wound fiberglass casing
• User-adjustable time delays in 2-second increments (for non-plugged motors)
• User adjustable ejection charge (for non-plugged motors)
• High reliability due to less potential for user error while retaining superior customer adjustability
• Low cost 

The motors listed on this page are all "Single Use," which means they can only be used once and then the entire thing, casing and all, is discarded. We also offer "reloadable motors" in which the casing can be cleaned out and used over and over.

What are the advantages of single-use motors?

1. They are simple and reliable. Just put the motor into the rocket and launch it!
2. They're readily available and, in an emergency, you can pick some brands up at local hobby shops.
3. Fastest turn-around times between flights of the same rocket means you can get a ton of flights done on the same day!
4. If you lose your rocket due to the wind, extreme altitude, or other, you're not out the investment of the much more expensive reloadable casing.
5. Safer to use by younger children, as the propellant and ejection charge are all sealed within the casing.

What is the disadvantage of single-use motors?

1. Single-use motors cost a little more per-flight than reloadable.
2. Larger single use motors, particularly with E class or higher, you often have to pay a HAZMAT fee, which can cause shipping to be upwards of $45. This is because only so much propellant can be in a continuous chunk before there is an assumed risk. Any motors that require the fee are marked.

You have to weigh the advantages versus the extra cost. We believe that there are a lot of cases where it makes sense to use them, which is why we carry so many different ones.

Let's take an example so you can see how to read the charts. As an example, we'll look at the "E28-4T" motor. 

Breaking it down, we have four bits of information. "E," "28," "4," and "T"

The first letter, "E," in our example, is the power level classification of the motor. If you look at the chart at the right, you can see that "E" motors range between 20 and 40 Newton-seconds of "Total Impulse". Each letter's maximum total impulse is twice that of the prior. For a full chart of impulse classification levels, check out the Wikipedia page. 

In our example, the E28-4T has 39.69 N-s of total impulse per the manufacturer, so it would be considered a "Full" E motor since it is so close to the maximum of 40 N-s.

The first number after the power letter is the average thrust level of the rocket measured in Newtons, equivalent to 0.225 pounds of force. That means in our example, the motor has an average thrust of 28 Newtons.

The number after the dash is the length of time in which the "delay" charge burns before it allows the ejection charge, which deploys your parachute, to go off. The delay allows time for the rocket to coast and slow down so the parachute doesn't rip out of the tube at ejection. In our example, the rocket would coast for 4 seconds before deployment.

Most single-use motors give a hard number for the delay, and you will need to purchase the appropriate one for your kit. Some loadable, larger single use or reloadable motors will often have a maximum delay that, with a specially designed tool, you can use to shorten the delay to what is best for your rocket. Look at the "Max Delay" statistic for that particular motor.  If it is an N/A, or not listed, you cannot adjust the delay.

A letter "P" after the dash, denotes that the motor is plugged, and does not have any ejection charge to push out the parachute. These motors will require the use of a dual-deployment altimeters to control events like parachute deployment.

In a special case for very large motors, if there is a letter "S" after the "-P" (example -PS), that tells us that the motor DOES have tracking smoke to help you see the motor in the sky. But it still does NOT have an ejection charge. An example would be the Aerotech L1090W-PS.

The letter after the delay* denotes the propellant type, aka color, of the motor (see the chart below showing what each flame color looks liket). Each brand uses a different lettering scheme. Our example is an Aerotech motor, and the "T" tells us that it is a Blue Thunder propellant. Propellant type doesn't affect the way your rocket flies, it just affects the way it looks at takeoff. See the image below to get an idea of what the flame will look like for the different chemical formulations. For more information on motor flame-color, see Peak-of-Flight Newsletter #217.

Note: The "T" for the Blue Thunder formulation can cause a little confusion since Estes use the "T" designation to indicate the size of the motor as being 13mm in diameter. See Estes Items for more about the "T."

*The propellant type may also come immediately before the dash on some high-power reloads. In the example of H123W-M, the ordering goes (Total Impulse)(Average Thrust)(Propellant)-(Delay)

Black Jack™ (J) and Black Max™ (FJ)  - Provides the high visibility tracking of dense, black exhaust. In addition to a distinctive lift off roar, Black Jack motors give your models lower acceleration and longer powered flight than White Lightning or Blue Thunder motors of the same total impulse. Black Max provides slightly higher acceleration than White Lightning Propellant.

Blue Thunder™ (T) - Produces a bright violet-blue flame with a minimum of exhaust smoke. These motors provide a higher level of thrust than White Lightning or Black Jack motors of the same total impulse. Blue Thunder is the perfect propellant for high lift-off acceleration.

White Lightning™ (W) - A brilliant white flame, dense bright white exhaust, and a throaty roar are the hallmarks of this popular propellant. Easy to track. Exciting to watch! White Lightning looks and sounds like actual sounding rockets and launch vehicles. Special effects professionals and aerospace companies specify the AeroTech White Lightning propellant to achieve realistic simulation.

Dark Matter™ (DM) - Dark Matter is a sparky propellant but unlike Metalstorm with it’s higher impulse and white smoke, Dark Matter is the black smoke sparky. These remind me of the old black powder Rocketflite Silver Streaks, which were legendary in the early days of high-power rocketry. As with all rocket motors using spark-generating propellants, special precautions must be taken to avoid fires around the launch pad by clearing the immediate area of all combustible materials in accordance with applicable fire and safety codes.

Metalstorm™ (M) - Metalstorm has completely different visual, audible and performance characteristics than the other sparky propellants currently on the market. Metalstorm ignites easily and produces a large, brilliant white exhaust plume, a much longer yellow-orange dense spark tail, plentiful white sparks that fan out in flight and an ample volume of white smoke.

Metalstorm’s high density and relatively high specific impulse results in a higher delivered total impulse for a given volume than some other sparky propellants. This characteristic makes Metalstorm "the performance sparky." Motor burn times using Metalstorm propellant are slightly longer than those produced by White Lightning™, but the total impulse is only slightly lower.

As with all rocket motors using spark-generating propellants, special precautions must be taken to avoid fires around the launch pad by clearing the immediate area of all combustible materials in accordance with applicable fire and safety codes

Mojave Green™ (G) - Mojave Green™ is one of AeroTech's newer propellants designed for its single use and RMS reloadable motors. Named for an infamous green rattlesnake with two types of venom that roams the Mojave desert, Mojave Green produces a brilliant green exhaust plume with a moderate amount of smoke. Mojave Green's high-density and specific impulse deliver a higher total impulse in each motor size than any other AeroTech propellant. Motor burn times using Mojave Green are similar to those produced by Redline™.

New Blue Thunder™ (NT) - This propellant color, formulated in high power motors, produces a beautiful blue exhaust jet studded with prominent “mach diamonds.”  They say it's got a much more intense blue than the standard Blue Thunder. 

Propellant X™ (X) - Propellant X is a high impulse propellant. It is a fast burning propellant with a long yellow/white flame and low smoke.

Redline™ (R) - Distinctly different from its propellant relatives, Redline provides unique visual and thrust characteristics for larger airframes and performance oriented flyers. The proprietary AeroTech formulation imparts Redline with its signature vivid scarlet flame. Redline's burning rate lies midway between that of White Lightning and Blue Thunder. Photos don't do justice to the "laser-beam" intensity and color of Redline… you have to see it to appreciate it!

Warp-9™ (N) - If you blink, you'll miss it! Displaying a prominent yellow-orange flame studded with "mach diamonds", Warp-9 is AeroTech's fastest-burning propellant. Originally developed for Orbital's Pegasus® fin motors, Warp-9 is perfect when you need the highest thrust possible from a given motor size. Alternatively, when used in an "end-burning" grain configuration, Warp-9 delivers unique thrust curve profiles such as that produced by the new G69N model rocket reload.

Super Thunder™ (ST) - Super Thunder produces a brighter violet-blue flame with a little more smoke than Blue Thunder (T). It is a fast burning propellant with a burn rate midway between Blue Thunder and Warp-9. According to Gary Rosenfield at Aerotech, the back-story is that they wanted a formulation with an intermediate burn rate to compete with the Cessaroni V-Max propellant formulation, but at a lower cost than Warp-9, which uses an expensive burn rate catalyst. In addition, they wanted a fast propellant that would still work with a pyrotechnic time delay. From a production standpoint, Aerotech also found that it casts better than the Warp-9 formulation, which means it can be used in smaller diamter motors (such as the 29mm motor - H13ST). The original name for Super Thunder was going to be “Warp-8”, but they settled on Super Thunder.

Classic™ (C) - "Classic Enerjet" propellant mimics the look, sound and performance of the original Enerjet propellant which was used in the first composite propellant model rocket motors from 1970 to 1974. For those modelers old enough to remember the Enerjet motors, this formulation will bring back fond memories from your youth. The "classic Enerjet" propellant formulation provides an impressive lift-off with visible supersonic shock diamonds emanating from a translucent exhaust plume and no smoke, that appears to make your rocket leap-off the launch pad. What's different is that today’s modern ingredients have a higher propellant “solids loading,” which is used to maintain the smokeless characteristic of the first Enerjets. As a benefit, these have a significantly higher “Isp” (propellant efficiency performance rating) and greater density than the original. That means they go higher!

The propellant descriptions are courtesy of Aerotech.

Composite Propellant -- in general terms -- means that the propellant is a mixture of ingredients (fuel and oxidizer substances) that when mixed together, solidify by means of a chemical reaction. By chemical reaction, it is similar to mixing up epoxy; when Part A and Part B are mixed, the chemical reaction causes the mixture to harden. By contrast, "Black Powder" propellant is a powdery substance that is "pressed" into a hard slug.

The reason composite motors cost a little bit more than black powder motors (such as the Estes or Quest motors) is because of this chemical formulation of the fuel inside. These motors use a high-energy propellant formulation; very similar to the type of propellant used in the Solid Rocket Boosters (SRB) of the Space Shuttle. What this means to us modelers is that when it burns, it gives off much more thrust per weight of the fuel. Composite motors are more than two times more efficient than black powder propellant rocket motors. They are smaller, and produce much more power!

But to get this extra power and higher efficiency, the ingredients that make up the propellant are more expensive than black powder. Not only that but the case that holds the propellant has to be much stronger to contain the higher pressure the gasses create as the propellant burns. So there is also the expense of this extra-strong case to hold it all together. You wouldn't want your motor to burst open because of a flimsy case, would you?

I know what you're thinking. You don't care about high-efficiency. You just want a cheap motor. Since black powder propellant is cheaper, why not use it to make big motors to save money? That is a great observation and shows you're thinking like a true rocket scientist. But unfortunately, there are two problems: technical and economic.

Technical Reasons

On the technical side, black powder when pressed into a rocket motor is very very brittle. In other words, it cracks easily. The bigger the motor, the worse the problem becomes. So if you dropped a large black powder motor on the ground, or it got really jiggled during shipping, it could easily get a hairline crack in it. That means when you launch it, the motor will burst open, and cause the model to crash and break. Would you want your bigger, more expensive rockets to be destroyed on their first flight?

This is the main reason you don't often see black powder rocket motors larger than a D or E size. With motors larger than this, the failure rate increases to the point where you destroy too many good rocket models.

By contrast, composite propellant is actually rubbery. It has the consistency of a pencil eraser. It doesn't crack or break like black powder propellant. So it can take a lot of abuse that the shipping companies usually seem to subject packages to. Your success rate increases exponentially. This is the reason that it is actually cheaper to use composite motors on mid-size and larger rockets. You won't be replacing the rockets because the motor burst open.

Economic Reasons

The bigger the black powder motor, the more difficult it is to make. The machinery is bigger and more expensive. Whereas, in composite motors, the production equipment doesn't change between smaller motors and bigger ones. So it becomes cheaper to make big composite propellant motors than making an equivalent size black powder motor.

These motors have many advantages. Serious modelers love them because:

• The high thrust gives you the extra oomph to get those big rockets into the air.
• Small size - when used in smaller models, they really scream out of sight.
• Brilliantly colored flame color, and loud roar make them a crowd pleaser when you launch them.
• Anyone can use them. They are legal in all 50 states and USA Territories!
• No Federal nor State Explosive Permits needed to possess or transport these motors.
• No "explosive storage magazine" required to store these motors in your house.

How do the sizes of these motors compare to the classic Estes motors? Check out the picture above!

Aerotech D motors are the smaller than the Estes D motors. They are actually 18mm, the same size as the Estes C, but go much higher! 

Aerotech E motors, and some F, are 24mm and will fit in the same mount that an Estes D does. Check the length, as the F32, for example, is longer, and will need a longer engine hook (Estes E-Size).

Most Aerotech F motors are 29mm, the same diameter as an Estes E. Aerotech G motors are 29mm, but longer than the F, so make sure your motor mount will accommodate them!

If you need help designing and building engine mounts, see our e-zine newsletter #104, or check out our motor mount kits.

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George C. -- 09/29/2023