Hold Those Expensive Reload Cases Secure In Your Rocket
Screw-on Engine Retainers

Product Specifications:

The set includes two pieces. One part is epoxied to the engine mount tube, and the other piece simply screws over the top after the rocket motor is inserted into the rocket. Made from aircraft-grade aluminum, and anodized a black color.

Aeropak retainer

Screw-on Retainer Order Chart
Engine
Size
P/N Tube Size

Mass (g)

Ring O.D. (mm) Ring Depth (mm) Vendor
Part No.
Place Order

18mm

24056 18mm (BT-20)
Works with all 18mm motors
See how to use this retainer with single-use 18mm motors (click here).
3.7 23 6 Rocket-arium
Image
24mm
24050 24mm (BT-50)
Works with all 24mm motors
7.4 31 8 Rocket-arium
Image

24mm

24051 Fits 24mm tubes with an O.D. of 0.976"
(Paper tubes from Apogee, Aerotech, Madcow)
6.8 30 13 Aeropack
RA24L1
24mm
24052 Fits 24mm tubes with an O.D. of 1.000"
(LOC & QModeling paper tubes, Madcow fiberglass* tubes)
6.8 30 13 Aeropack
RA24L2
29mm 24060 Fits 29mm tubes with an O.D. of 1.215"
(LOC, Apogee, Madcow paper tubes)
15.9 40 13 Aeropack
RA29L1
29mm 24064 Fits 29mm tubes with an O.D. of 1.225"
(Q-Modeling tubes, Madcow fiberglass* tubes, Sunward & Semroc MMTs)
15.9 40 13 Aeropack
RA29L2
29mm 24061 Fits 29mm tubes with an O.D. of 1.270"
(Blue Tube,* PML and Giant Leap phenolic tubes, Performance Rocketry and Hawk Mountain fiberglass tubes, AeroTech)
**AeroTech Kits are slightly small for the RA29P, so you will need to add a layer of tape or similar tactic.
14.8 40 13 Aeropack
RA29P
38mm 24062 Fits 38mm tubes with an O.D. of 1.630"
(LOC paper tubes )
22.7 50 12 Aeropack
RA38L
38mm 24063 Fits 38mm tubes with an O.D. of 1.650"
(Madcow kits, Blue Tube,* PML and Giant Leap phenolic tubes, Performance Rocketry and Hawk Mountain fiberglass tubes)
21.1 50 12 Aeropack
RA38P
54mm 24066 Fits 54mm tubes with an O.D. of 2.265"
(LOC/Precision and Madcow paper kits and paper tubes)
40.6 66 19 Aeropack
RA54L
54mm 24067 Fits 54mm tubes with an O.D. of 2.278"
(PML and Giant Leap phenolic tubes, Madcow*, Performance Rocketry and Hawk Mountain fiberglass tubes from )
40.6 66 19 Aeropack
RA54P
54mm 24068 Flanged version, which attached to the lower centering ring instead of the motor mount tube using socket head screws. The min. I.D. of the airframe tube is 3.00". 64.5 75 19 Aeropack
RA54**
75mm 24069 Flanged version, which attached to the lower centering ring instead of the motor mount tube using socket head screws. The min. I.D. of the airframe tube is 3.90". 140.8 98 30 Aeropack
RA75**

Other Aeropack sizes (such as 75mm and 98mm) are available, but require a special order. Please call us at 719-535-9335.

*Some sanding will be required to make a good fit on the Blue Tubes and Madcow fiberglass.

**Includes hardware in mass.


Features of the Screw-on Motor Retainers

Do you think engine hooks or tape look ugly to hold the rocket motor in your model? Then you'll love the screw-on motor retainers. It gives your rocket a professional and finished look that a high quality rocket deserves.

What does it do? Simply, it also holds the engine in the rocket so it can't be spit out by a strong ejection charge. A secondary feature is that it allows you to quickly swap out the used-up motor for a new one in seconds. It is as simple as screwing off a bottle-top. Just twist off the cap, swap out the motor, and twist the cap back on to hold the engine in place.

How do you install it? Installation is very simple. Just bond the threaded portion to the aft end of the engine mount tube using some good high-temperature epoxy such as JB Weld. The cap portion is twisted on after the motor is placed in the vehicle.

Features Include:

  • Two-piece, light-weight assemblies fits all standard reloadable and single use motors

  • Precision machined 6061-T6 aluminum with mil-spec type II black anodizing for wear and corrosion resistance

  • Large Quick-Turn Threads for Fast Tool-Free Motor Change

  • Compatible with the following solid fuel rocket motors: AeroTech™ / AMW™ / APS™ / Cesaroni ProX™ / Kosdon™ / Loki™

  • Can Be Added to Existing Rockets with Extended Motor Mount Tubes
Engine Retainer

Motor Retainer

Materials needed to assemble the engine retainer:

  • High temperature epoxy, such as JB Weld brand.

Alternate Methods To Restrain Rocket Motors

Engine Retainer

The old method of restraining motors using a metal plate that screws into the base of the rocket is another option. We carry these under the Madcow Rocketry Engine Retainers.

The advantage is that they can be installed on rockets that are already constructed, or they can be used on rockets where the engine tube is flush with the centering ring (making a flat-bottomed rocket that will stand up on a display shelf). They also cost a bit less than the AeroPack retainers shown on this page. Click here for more information.


Video Tutorials

Laminate your fins

How To Restrain Rocket Engines

In this free YouTube video, we'll answer the most common questions that people ask us about restraining the motor in the rocket. You'll see how to tape the motor in, as well as using engine mount retainers shown on this page.

Building Your First High Power Rocket - Part 4, Rail Button Installation

Building Your First High Power Rocket - Part 4, Rail Button & Retainer Installation

Putting together a high power rocket is actually easier than you might imagine. In this fourth video, you'll see how install rail buttons and the Aeropack engine retainer.  Tune in at minute 7:28.


Frequently Asked Questions about the Screw-on Engine Retainers:

Q. What length exposure of the motor mount tube is required to mount the base of the Aero Pack retainer?

A. You need to leave at least 1/4" (6.3mm) of the tube exposed out the rear of the rocket. You can always trim down the tube if it is too long, but you can't make it longer...

Q. How do you pick the right size motor retainer?

A. Watch the video below that describes the process.

Q. The Aerotech kits have engine hooks. Can I use these engine retainers with Aerotech kits too?

A. Yes. But you have to remove the engine hook and the thrust ring from the kit. If the kit hasn't been constructed yet, it is easy to do. Watch the video above that describes the process.

Q. Do these engine retainers work with "single use" motors too?

A. Yes they do!

Related Items and Optional Accessories That Go Great With These Items:
Aero Pack Tailcone Engine Retainers

Want to hold in your rocket engines securely and reduce drag at the same time? Then the Aero Pack Tailcone retention system is you're looking for. They currently come in sizes for 38mm and 54mm engines fitting body tubes with approximately 3" and 3.9" I.D.

Tailcone Engine Retainers
Madcow Rocketry's Engine Retainers

These engine retainers hold reloadable rocket motors securely in the model so they can't be kicked out by a strong ejection charge. These are much less expensive than other engine retainers, and can be retrofitted onto rockets that are already constructed and ready to fly. They also work great on flat-bottom rockets where the engine tube is flush with the centering ring.

Madcow Engine Retainers

Motor Mount Adapters

These adapters allow you to put a smaller diameter motor into a rocket that has a motor mount tube up to two sizes larger. This is a great way to save money by putting a smaller motor in a big rocket.

Motor Adapter
High Power Nose Cones

These are high power nose cones that fit both the LOC kraft-paper tubes, as well as the Blue Tubes. The tubes are made out of Polypropylene plastic or fiberglass, which makes them very durable so they'll take the abuse of any high power motor you care to put behind them.

High Power Nose Cones
Tube Couplers For Large Diameter Rockets

These regular Kraft-paper couplers fit the same tubes as the Blue Tube Couplers. So if we're out of a size of the Blue Coupler you need, this could be an alternative you may want to consider.

Tube Couplers for High Power Rockets

Blue Couplers

To go along with the Blue Tubes, here are the couplers that can join them together to make longer rockets. These will also fit the standard size LOC tubes, and those other high power manufacturers that make the tubes to standard sizes.

Electronics Bays

These payload bays from Always Ready Rocketry fit most of the standard size Blue Tube, as well as tubes from LOC Precision. They are designed to hold the avionics or electronics that control the deployment of the parachutes in the rockets. It is a complete kit, all you have to do is supply the electronic payload to control when the ejection charges fire.

Payload Bays

Motor Mount Adapters

These adapters allow you to put a smaller diameter motor into a rocket that has a motor mount tube up to two sizes larger. This is a great way to save money by putting a smaller motor in a big rocket.

Motor Adapter
Rail Buttons

Rail Buttons are used in place of launch lugs on larger rockets. The reason is that big rockets need a stiffer launcher so they don't sway around in breezy conditions. A launch rail is much stiffer than a circular rod, and therefore are used on big rockets so they launch safely and higher into the sky.

Rail Buttons
High-Power Capable Parachutes

SkyAngle parachutes were designed and constructed specifically to handle the extra stress of high power rockets. Because of the extra weight of the bigger rockets, they have more than their share of parachute malfunctions. The SkyAngle parachutes are more durable, and bring your big rockets down slower.

High Power Rated Parachutes
Sky Angle Parachute Deployment Bags

A deployment bag is a device to help ensure that parachute inflates properly and in the correct order. It forces the lines to completely stretch out first, and then the canopy is released so that it can properly inflate. It also minimizes the loads on the suspension lines to prevent tears, and it gives additional protection from the heat of the ejection charges. If you're doing high power rockets, you really need this extra insurance to make your project a success.

Sky Angle Parachute Deployment Bags
Spring steel engine retainer clips

Used on small rockets, these engine hooks to allow you to swap out engines between flights in just milliseconds. It is really that fast!

Modern High Power Rocketry

Actual Customer Comment:
"Just wanted to thank you for your excellent service and website. I ordered an Apogee Aspire last week and it arrived yesterday. I've just put it together and everything looks great. I was surprised that it arrived less than a week from when I ordered, considering I live in Sweden! When I sent you an email with a question I got an answer within an hour. That's really great service! In short I very much feel that I've gotten my money's worth. Thank you!" -- Christian Monegard (Sweden)