Hold those Expensive Reload Cases Secure In Your Rocket

29mm Estes Retainer

  • Part Number (PN): 24020
  • Qty per pack: 2
  • Weight: 13.3 g (0.47 oz)
  • Length/Thickness: 1.16" (2.96 cm)
  • Inner Diameter: 1.219" (3.1 cm)
  • Outer Diameter: 1.739" (4.42 cm)
  • Manufactured by: Estes
  • Product Specs:
  • They are designed for thick wall Estes Pro Series and LOC 29mm tubes. 

Product is in Stock (10+)

Retainer Set - The Estes 29mm engine retainers are used to hold big motors in your F and G size rocket kits. The advantage is they are cheaper in price, and that will save you money for your other projects. They are designed for thick wall Estes Pro Series and LOC tubes. 

Estes 29mm Motor Retainer Set

Estes 29mm engine retainer for model rocketsWhy use a retainer? Because engine hooks are not versatile on big rocket engines, like anything that is 29mm in diameter or greater. The main reason is that the length of the different motors changes, so the hooks don't fit. The solution to this problem is an engine retainer system that grabs on to the back of the motor and prevents it from moving up into the tube, or rearward out of the tube when the ejection charge pushes the nose cone out.

These engine retainers from Estes are made from a durable plastic. The adavantage of them is that they are inexpensive. You get a two-pack of engine retainers for less than the cost of a single retainer from other manufacturers.

The questions you have are: "Are they strong?" and "Will they last?" The answer is "yes" to both questions. While plastic is not nearly as strong as machined aluminum, they are strong enough. In reality, they only need to be strong enough to prevent the motor from kicking out the back of the rocket when the ejection charge pushes the parachute out. And you really don't need a lot of strength to do that. So they are plenty strong.

Also, they don't really take a lot of heat from the motor, so they do last a long time. You're likely to lose the rocket before the retainers ever break.

The only minor concern that we have about durability, although we've never seen this happen to anyone, is that the rocket land hard on the engine retainer and crack the plastic. If the rocket lands that hard on the engine mount, you'll probably have other significant damage to the rocket besides just the retainer cracking. You might want to compensate by using a slightly larger parachute than you intended originally so that the rocket comes down slower and the landings are a little gentler.

Estes 2-part Rocket engine retainer systemTo use these retainers, you'll first scuff up the inside of the inner ring with sandpaper. This will allow your adhesive to better grab to the plastic ring. For the adhesive, Estes recommends epoxy. I believe that regular 5-minute epoxy you purchase at a hardware store will be sufficient for most rockets.

The inner ring is slid over the top of the engine mount tube (which needs to extend out from the aft centering a minimum of 0.5 inches {12.7mm}). This part fits nicely on LOC 29mm tubes.

NOTE: THERE IS NO OTHER SIZES FROM ESTES FOR DIFFERENT DIAMETER TUBES! So don't ask us if it will fit tubes made by other manufactures. You CAN make it fit. Here is what you can do...

If your tube is too small and the retainer is loose and sloppy on the tube, you'll need to build up some thinkness on the tube with some epoxy. For slight differences, you can use liquid epoxy. For large gaps, us the Fix-It Epoxy Clay. To make sure the retainer stays concentric with the motor tube, slide an engine casing into the retainer while the epoxy is curing (use care not to get epoxy on the casing, or you could bond it permanently into the engine tube).

Engine Retainer installedIf the retainer is too tight on the tube of your rocket, we recommend sanding out the inside of the retainer (not the outside of the engine tube). It is plastic, and it will sand. Fortunately, Estes made the wall thickness pretty beefy. So there is plenty of material available to fit on most any 29mm tube. And you can use a dremel type sander to make the work go faster.

This may make the hole too large, and not perfectly round. So intentionally make the fit a little loose on the tube by sanding the hole too big. And as above, to make sure the retainer stays concentric with the motor tube, slide a rocket engine into the retainer when you epoxy the retainer onto the tube. This will force it to become perfectly aligned with the tube and insure that the thrust from the motor is parallel and concentric with the engine tube.

Features of the Screw-on Motor Retainers

Engine RetainerDo 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.


Motor RetainerFeatures 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


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. 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!

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Comparison - Screw-on Retainers (29mm)
Product P/N Qty/ Pack I.D. O.D. Length Weight Fits Part Other PN Price Buy Now!
Aero Pack 29mm Retainer - L 24060 1 1.215"
#11004 RA29L
Aero Pack 29mm Retainer - L2 24064 1 1.225"
Fits 29mm tubes with an O.D. of 1.225" (LOC & Q-Modeling tubes, Aerotech - sanding required) RA29L2
Aero Pack 29mm Retainer - P 24061 1 1.27"
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**) RA29P
29mm Estes Retainer 24020 2 1.219"
#11004 --
AeroPack 29mm Retainer Body - L 24105 1 1.215"
-- #24060 RB29L
AeroPack 29mm Retainer Body - L2 24106 1 1.225"
-- #24064 RB29L2
AeroPack 29mm Retainer Body - P 24107 1 1.27"
-- #24061 RB29P
Aero Pack 29mm Retainer Cap 24104 1 -- -- -- -- #24105
Frequently Asked Questions about the 29mm Estes Retainer
Q:How do you pick the right size motor retainer?
A: Watch the video below that describes the process.

Q:My kit has an engine hook. Can I use these engine retainers with this kit 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!

A: Unfortunately, no. The ring on the Aeropack 24/29mm adapter is too large to fit into the 29mm Estes retainer screw-on cap.

Q:What length exposure of the motor mount tube is required to mount the base of the 24mm and 29mm Aero Pack retainers?
A: You need to leave at least 1/4" (6.4mm) 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...

Reviews for the 29mm Estes Retainer
Current Reviews: 3

Random Selected Reviews:

4 of 5 Stars!Andrew Molnau -- 01/16/2013
Works rather well and I am not worried about it being plastic

5 of 5 Stars!Alexander Solis -- 05/12/2015
For the price of two, it cant get no better than that. Excellent quality and about all a must have when using 29mm motors.

4 of 5 Stars!Anthony DeVita -- 06/05/2015
I've used the aluminum retainer in the past and this is the first plastic type for me. It's lighter in weight and mounts easily. Two for less than the price of one aluminum retainer. I don't believe heat will be an issue during launch. The plastic is quite rugged. Will give a post-flight review.

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