Motor retainer question

[Gunstar]

Typically when I build something I'll use an engine hook, but I'm considering giving motor retainers a try. With an engine hook you have 1/4 inch of the motor sticking out past the end of the tube, but from what I can see in pictures it looks like the threaded part attaching to the tube goes right to the end of the motor and the cap screws on flush (inside) to the threaded part. Doesn't that make it hard to remove the motor, or am I missing something?

 

[techrat]

Yes. It's a little more difficult to remove the motor. And if you're working with mostly 18mm motors, the hook is just fine. However, once you move past that, you'll find with larger 24mm (E motors) or 29mm motors (F, G) that a hook is not enough. Also be aware that while Estes BP motors have no retainer ring, composite motors with their phenolic casings do have a ring that sits between the lower end of the retainer and the cap of the retainer that makes removal of the motor a snap.

 

[mh9162013]

I think your understanding is correct, as is the additional information from @techrat. However, when using the Estes plastic screw-on retainer with 18mm BP engines, I never had issues with engine removal; just point the rocket up and do a light shake - the engine should come out no problem.

 

[kuririn]

The screw on retainer will work with the motor sticking 1/4" out. It doesn't need to be flush. That's what you do when loading composite motors anyway right? Because there's a 1/4" rear flange molded into the casing. So just tape a 1/4" rear flange on your BP motor using several layers of 1/4" masking tape. Screw on the cap hand tight. Then removal is a snap.

 

[Back_at_it]

The Estes retainers allow room for you to have the motor exposed approx. 1/4". If you are still running black powder motors you will need to make a ring around the outside of the motor or use a motor block inside the tube. If you choose to do the motor block, be sure to use the motor retainer when figuring the location of the motor block inside the tube.

I'll typically put a motor in the retainer then use that to push the motor block into the correct location in the tube.

 

[mh9162013]

I'll typically put a motor in the retainer then use that to push the motor block into the correct location in the tube.

That's what I do, too. I also try to use a shorter-than-normal spent engine casing to do this with. Reason being Estes BP 18mm engine lengths vary by about +/- 1mm and I want to avoid a situation where I get a shorter engine, but I can't keep it from wiggling back and forth 0.5 to 1mm or so because the retainer has already "bottomed out."

 

[Patternflyer]

I set my engine block in the motor mount in such a way that the motor sticks out 3/16" to 1/4". This allows for plenty of threads on the retainer cap to hold.

 

[novahobbies]

Just a heads up, when you make your tape flange and if you use duct tape, make sure to remove the motor as soon as it comes down. I didn't think to remove an estes BP F motor from my Leviathan the first time she flew until weeks after....and by then the black gorilla tape had more or less managed to "glue" the wrap onto the motor mount! Had to use a part of a launch rod stuffed down from the nose end to dislodge it. Tape was super sticky.

 

[bjphoenix]

Typically when I build something I'll use an engine hook, but I'm considering giving motor retainers a try. With an engine hook you have 1/4 inch of the motor sticking out past the end of the tube, but from what I can see in pictures it looks like the threaded part attaching to the tube goes right to the end of the motor and the cap screws on flush (inside) to the threaded part. Doesn't that make it hard to remove the motor, or am I missing something?

You can use an engine hook with the engine closer to flush with the end of the motor mount. If you leave nearly 1/8" sticking out you can grab the end of the motor with pliers to pull it out. Or if you make the motor flush with the motor mount you can poke it out from the front with a long dowel. Also I remember very long ago there was a suggestion to make a tool to pull engines out by taking a piece of coathanger wire and bending over a small piece on the end. You could stick through the hole in the engine nozzle and pull the engine out that way.

 

[49markt]

You can use an engine hook with the engine closer to flush with the end of the motor mount. If you leave nearly 1/8" sticking out you can grab the end of the motor with pliers to pull it out. Or if you make the motor flush with the motor mount you can poke it out from the front with a long dowel. Also I remember very long ago there was a suggestion to make a tool to pull engines out by taking a piece of coathanger wire and bending over a small piece on the end. You could stick through the hole in the engine nozzle and pull the engine out that way.

Ive been using a nozzle hook for 40 years. Works every time.