RMS questions

If you will indulge me please-

I'm kicking around the idea of getting one rocket or another that will use a 29mm motor, but as I have only ever used single use Estes engines (18 & 24mm), a couple of questions come to mind. I've spent quite a bit of time looking around and think I know the answers, but for one reason or another, I'm just not quite sure if I understand for sure. You know?

I'll use the AeroTech RMS-29/40-120 as an example for asking purposes-

1. If I understand correctly, using this one casing I could reload it to 7 different thrust levels for use either in different rockets or for varying heights/weights?

2. These motors don't generally use a motor retention clip/spring like the Estes kits. They may use something like the Motor Retention System from Giant Leap Rocketry that performs both functions of keeping the motor from going up through the bodytube and from being shoved out the end at ejection. Does this sound about right?

3. If the rocket is small and light enough to fly on Estes E's and D's, there are adapters available to allow this. Right? Wrong?

4. Or..... I could get and build a rocket with a 38mm motor housing and an adapter to use a 29mm motor in it until I decide if I want to get active enough to get Level 1 certified. Of course, by that time I'll probably be ready to build another, larger roc..... Oh, sorry. Started rambling.

Sorry if these are low-brow questions; I'm kind of at that stage where "I think I would like to get more into this", but don't have anyone around in person that would have made watching and learning the way to go.

Thanks all, Have a good one,
Greg

All of these are in fact, very good & valid questions See answers below...

Originally posted by 11Bravo
If you will indulge me please-

I'm kicking around the idea of getting one rocket or another that will use a 29mm motor, but as I have only ever used single use Estes engines (18 & 24mm), a couple of questions come to mind. I've spent quite a bit of time looking around and think I know the answers, but for one reason or another, I'm just not quite sure if I understand for sure. You know?

I'll use the AeroTech RMS-29/40-120 as an example for asking purposes-

1. If I understand correctly, using this one casing I could reload it to 7 different thrust levels for use either in different rockets or for varying heights/weights?

Click to expand...

Yes. The AT 29/40-120 is the only casing available with that amount of flexibility. As you step up to larger motors, there are typically no more than 3 or 4 reloads available (& they are only the different kinds of propellant formulas) per casing.

Originally posted by 11Bravo
2. These motors don't generally use a motor retention clip/spring like the Estes kits. They may use something like the Motor Retention System from Giant Leap Rocketry that performs both functions of keeping the motor from going up through the bodytube and from being shoved out the end at ejection. Does this sound about right?

Click to expand...

You have the right idea. Motor retention for MPR/HPR is quite different from LPR rockets. The Giant Leap retainer is certainly an acceptable way to accomplish that. There are plenty other solutions (some cheaper, some more expensive) available. Do a search here on TRF for "motor retention" for more info/ideas.

Originally posted by 11Bravo
3. If the rocket is small and light enough to fly on Estes E's and D's, there are adapters available to allow this. Right? Wrong?

Click to expand...

You can always adapt down to a smaller motor size, but never adapt up

Originally posted by 11Bravo
4. Or..... I could get and build a rocket with a 38mm motor housing and an adapter to use a 29mm motor in it until I decide if I want to get active enough to get Level 1 certified. Of course, by that time I'll probably be ready to build another, larger roc..... Oh, sorry. Started rambling.

Click to expand...

Same as the previous answer

Originally posted by 11Bravo
Sorry if these are low-brow questions; I'm kind of at that stage where "I think I would like to get more into this", but don't have anyone around in person that would have made watching and learning the way to go.

Thanks all, Have a good one,
Greg

Click to expand...

Pay a visit to the NAR & Tripoli websites. See if there is a club in your area. We rocketeers are a friendly bunch and are always willing to help out & answer questions for a newcomer. It indeed will make a lot more sense when you see it in person!

HTH,

Originally posted by lalligood


You have the right idea. Motor retention for MPR/HPR is quite different from LPR rockets. The Giant Leap retainer is certainly an acceptable way to accomplish that. There are plenty other solutions (some cheaper, some more expensive) available. Do a search here on TRF for "motor retention" for more info/ideas.

Click to expand...

The exception here is Aerotech kits. The AT kits have built in retention with a motor hook - much like Estes. Beyond that, Lance is exactly right.

Loopy

2. These motors don't generally use a motor retention clip/spring like the Estes kits. They may use something like the Motor Retention System from Giant Leap Rocketry that performs both functions of keeping the motor from going up through the bodytube and from being shoved out the end at ejection. Does this sound about right?

Click to expand...

the aft closure ring on the motor is larger than the case so that keeps the motor from going up,
so you really only need a device to retain the motor from spitting out when the ejection charge fires.. this also eliminates the need for a forward motor block

One more comment, you can certify on 29mm, but building for 38mm and adapting down certainly gives you more options.

The LOC Graduator is a great MPR rocket that you can fly on lots of moderate loads in the 29/40-120 and then certify on in a 29/180 or 29/240 case. The H97J is a great motor for this bird, though you'll end up hiking