question regarding 24mm RMS cases

[paul.nortness]

Hey all,

I am getting ready to make the leap to RMS and I have a question I hope you can answer.

I am interested in going with a 24mm case and flying rockets like my Estes Executioner and Big Daddy on Aerotech E's. What is the length of the 24mm case? Is it similar in length to an Estes "D" or closer to the longer "E" class motor?

Thanks

[gdiscenza]

The 24/40 case is equivalent to the Estes "D" motor, and the 24/60 case is equivalent to the Estes "E" motor.

G.D.

[qquake2k]

I've flown my stock Executioner several times with the 24/40 case. Works very well!

[paul.nortness]

Cool. thanks guys.

I guess I actually have two questions. When selecting a reload, how do I know which is 24/40 and which is 24/60?

EDIT - scratch that....looks like everything but the F35W is 24/40

[qquake2k]

Cool. thanks guys.

I guess I actually have two questions. When selecting a reload, how do I know which is 24/40 and which is 24/60?

EDIT - scratch that....looks like everything but the F35W is 24/40

As far as I know, the only load available for the 24/60 is the F35. But there are at least 8 different loads available for the 24/40, from D9 to F39.

[Pantherjon]

Also, on the CTI side the lengths of their 24mm cases:
1 grain 3.73" (equivalent to Estes 'E')
3 grain 5.23"
6 grain 8.98"

[shreadvector]

When using the RMS casing in an Estes rocket, you need to file away the upper protruding portion of the metal motor clip that comes with the kit. It extends past the trhust ring (20/50 ring) enough to interfere with the delay housing of the RMS motor.

If the rocket is a kit that can use an E9 or E12 motor and uses D12 or C11 motors with the 1 inch spacer, then you can simply use the 24/40 casing with the spacer and it will be fine.

Secure the motor well so it does not eject. Losing a casing is bad.

[qquake2k]

I just put a wrap or two of masking tape around the bottom of the 24/40 case and the motor hook. Haven't lost a case yet, knock on wood. I've also seen people use wire or zip ties.

[paul.nortness]

Hey guys, thanks for all the answers and help!

Just a thought.....would it be possible to make an adapter for the 24/40 case to fit a 29mm motor mount and fly the Estes Pro Series rockets on F39T reloads?

If so, then I could use the 24/40 case for both my Executioner with E reloads and then with Pro Series rockets as well.

[troj]

Yep. Adapters work well, and become more common as folks move to bigger motors

As always, the motor has to be big enough for stable flight

[paul.nortness]

Thanks Troj.

So it looks like a F39T reload has total impulse of 50 N-Seconds while the F26FJ single use has 65 N-seconds. Is the the F39T going to be strong enough to launch the Estes Pro Series Ventris? Or am I selling myself short trying to use a smaller motor in a rocket like that?

[shreadvector]

Look at the Manufacturer's recommended maximum liftoff weight for the motor and delay you are considering. If the fully built and painted rocket with motor installed weighs less than or equal to that weight, then it is OK.

This works for any motor and any rocket.

[UncleVanya]

So it looks like a F39T reload has total impulse of 50 N-Seconds while the F26FJ single use has 65 N-seconds. Is the the F39T going to be strong enough to launch the Estes Pro Series Ventris? Or am I selling myself short trying to use a smaller motor in a rocket like that?

This is going to depend on the final weight of the rocket as you build it. You can do as Fred says or use something like Thrustcurve.org's motor guide to get a basic sanity check. Current field conditions will also need to be considered - A good example is that the minimum velocity needed for stability changes with wind conditions. If you have any doubts just ask the RSO or others at the launch for advice.

[qquake2k]

Hey guys, thanks for all the answers and help!

Just a thought.....would it be possible to make an adapter for the 24/40 case to fit a 29mm motor mount and fly the Estes Pro Series rockets on F39T reloads?

If so, then I could use the 24/40 case for both my Executioner with E reloads and then with Pro Series rockets as well.

LOC makes a 24-29mm adapter.

http://www.hobbylinc.com/htm/loc/locmma1.htm

[paul.nortness]

RSO? Others at the launch?

It's usually just me and a couple of field mice out there

[bobkrech]

Thanks Troj.

So it looks like a F39T reload has total impulse of 50 N-Seconds while the F26FJ single use has 65 N-seconds. Is the the F39T going to be strong enough to launch the Estes Pro Series Ventris? Or am I selling myself short trying to use a smaller motor in a rocket like that?

Your doing a bit of an apples and oranges comparison.

The F39T is a 24 mm x 70 mm motor and the F26FJ is a 29 mm x 98 mm motor.

The F39T motor has about 22 grams of propellant while the F26 has about twice that because the case volume is larger, but Blue Thunder is a more efficient propellant than Fast Black so ithas more push per unit weight

The F39T is a better motor for a heavier rocket because it has more thrust. The more thrust a motor develops, the more weight it can lift safely off the pad. The a rocket with more total impulse has the potential to go higher than a rocket of the same weight but a lower total impulse, however there are limits. If the thrust is too low, the rocket will turn into the wind and the ascent will not be vertical. At some point if the wind is strong, the low thrust, longer burning higher impulse motor will be driving the rocket horizontally and not vertically. If you chose the motor with a delay that was designed for a vertical flight apogee the ejection charge is likely to go off after the rocket has hit the ground.

This is one reason why we run sims to illustrate the influence of thrust, weight, total impulse, drag and wind. These 5 parameters coupled together determine how high your rocket will go, how far from the pad the rocket ill travel, and if the recovery will be successful and in-field.

Bob

[Handeman]

Just get the 29/40-120 Hobbyline case right away, you'll get one eventually anyway. Besides, that 24/40 will get lonely in the range box without his big brother.

[Rocketbuilder]

Just as a side note, the forward closure on the 24/40 case fits perfectly inside the Estes D to E adapter, allowing it to fit in E sized MMTs. Coincidence? Could be, but I suspect the adapters were deliberately designed that way.

[Trident]

Just get the 29/40-120 Hobbyline case right away, you'll get one eventually anyway. Besides, that 24/40 will get lonely in the range box without his big brother.

Dittos on that. I own two each of the 29/40-120s, two each of the 24/40s, and also added an 18/20 to fly Mars Lander and Outlander on D reloads. They are an incredibly happy family.

[gdjsky01]

Paul sounds like you got all the advice you'll need. I agree with Fred, several of my rockets required me to file away a bit, though not all, of the forward retention hook protrusion or the delay housing of the RMS casing would not clear it. It took a little work, but it fits perfect then. Like others, I put at wrap of tape around the hook at the rear just to be sure.

And you've discovered that the 24/40 means (roughly) 24mm 40ns. The F's for that casing are baby F's. Can't seem to get many people to understand just because it says F does not mean it's double the power of an E. It's anywhere from 41ns to 80ns. That range is all F. But you seem to have a handle on that.

Enjoy. I have the 24/40 and the 24/40-120 (3 of each... I like clusters!) and a whole bunch more! CTI 24's are fun fun fun... but not 'standard' lengths.


BTW: I consider the 24/40 to be standard equipment for The Launch Pad size and style rockets.

[MarkII]

RSO? Others at the launch?

It's usually just me and a couple of field mice out there

Well, just be sure to give them a Head's Up, then. They will surely appreciate it.

[Pantherjon]

Especially the mice, so they can evacuate their tunnels for recovery!

[pick1e]

LOC makes a 24-29mm adapter.

http://www.hobbylinc.com/htm/loc/locmma1.htm

I'm in the same boat at paul.nortness, I have only flown Estes 18mm and 24mm motors up until now. I ordered this adapter along with an AeroTech 24/40 case and some F reloads for my Estes Ventris. Just received everything in the mail today.

With the LOC adapter, I expected more for my $2 than just a tube, oh well What do people do for the retaining lip on these? (Not certain what you call it, the lip or ring in the aft closure of the RMS cases that butts up to the MMT.) I hate using tape. Could I remove the foil around the last 1/4" and glue on a couple layers of a 1/4" strip cut from body tube? The Estes Pro-II Series screw-on retainer isn't going to accept much of a lip on the end, certainly not a 1/2" width of masking tap that the LOC instructions recommend!

Also, how about retaining the 24/40 RMS case in the LOC adapter tube? I didn't think the 24mm RMS case had a lip on the aft closure, but mine does. Is this sufficient to bear the thrust or isn't it made for that like on bigger cases? Then- retaining the 24mm case for ejection- is friction fit with masking tape sufficient? With the LOC adapter there is no retaining mechanism.

TIA guys.

Just as a side note, the forward closure on the 24/40 case fits perfectly inside the Estes D to E adapter, allowing it to fit in E sized MMTs. Coincidence? Could be, but I suspect the adapters were deliberately designed that way.

Just a note, mine did not. I needed to peel away a layer from the Estes D to E adapter. Luckily I had one new in a kit, the others have all been soaked in CA so I can't peel them.

[qquake2k]

I'm in the same boat at paul.nortness, I have only flown Estes 18mm and 24mm motors up until now. I ordered this adapter along with an AeroTech 24/40 case and some F reloads for my Estes Ventris. Just received everything in the mail today.

With the LOC adapter, I expected more for my $2 than just a tube, oh well What do people do for the retaining lip on these? (Not certain what you call it, the lip or ring in the aft closure of the RMS cases that butts up to the MMT.) I hate using tape. Could I remove the foil around the last 1/4" and glue on a couple layers of a 1/4" strip cut from body tube? The Estes Pro-II Series screw-on retainer isn't going to accept much of a lip on the end, certainly not a 1/2" width of masking tap that the LOC instructions recommend!

Also, how about retaining the 24/40 RMS case in the LOC adapter tube? I didn't think the 24mm RMS case had a lip on the aft closure, but mine does. Is this sufficient to bear the thrust or isn't it made for that like on bigger cases? Then- retaining the 24mm case for ejection- is friction fit with masking tape sufficient? With the LOC adapter there is no retaining mechanism.

TIA guys.

Just a note, mine did not. I needed to peel away a layer from the Estes D to E adapter. Luckily I had one new in a kit, the others have all been soaked in CA so I can't peel them.

I think if it were me, I would attach some sort of thrust ring to the outside of the adapter. Not sure how I'd do it, though. Probably peel off the foil and epoxy something in place. I might even try to make a ring out of 1/4" plywood, but I don't know what your capabilities are. As for retention, I would have put tee-nuts in the aft centering ring and made some sort of mechanical retention, like clips or a plate (see photos). But in your case, if you were to do something like that, you'd have to go with well nuts or inserts, and I'm not sure how much room you have in the centering ring. Hopefully some others will have ideas.

As for the E to D adapters, I've never had a problem with the BP well of my 24/40 cases fitting into them. I've used adapters from Estes and Mercury Engineering. Maybe you just got one from a bad batch.

[Wayco]

I bought a couple of the LOC adapters and was disappointed in them too. Not only did they not have a thrust ring, but they didn't fit in my MMT! I had to strip off the outer layer and sand them down to fit. I used some 1/4" trim tape to add the thrust ring, but it didn't come out very good, so I used some CA glue to strengthen it. I'm thinking about spending the big bucks and getting the Aeropac version:
http://www.aeropack.net/webstore/product.asp?productid=349346352565805

Anybody have any experience with them?

[qquake2k]

I'm going to dig out my LOC adapter this weekend and see what I can do with it. If it's that lame, I better get it set up before I need it.

[jimzcatz]

I bought a couple of the LOC adapters and was disappointed in them too. Not only did they not have a thrust ring, but they didn't fit in my MMT! I had to strip off the outer layer and sand them down to fit. I used some 1/4" trim tape to add the thrust ring, but it didn't come out very good, so I used some CA glue to strengthen it. I'm thinking about spending the big bucks and getting the Aeropac version:
http://www.aeropack.net/webstore/product.asp?productid=349346352565805

Anybody have any experience with them?

WOW!!! Do you have to make it so complicated. griping about no thrust ring? I mean cmon. You cant use trim tape, need 1/2" masking tape. I have been using the loc adapters for years. I cut them in thirds and get 3 out of them.It is not lame, its the easiest and best out there for the money. And whats wrong with it not fitting? How often to you have to peel a D12 to fit? While I will admit not alot as of recently, but it was regular practice a few years ago. So you peel a few layers of paper off, beats having to sand it to fit. OK, My rant is over...enjoy your regularly scheduled forum.

[terryg]

I bought a couple of the LOC adapters and was disappointed in them too. I'm thinking about spending the big bucks and getting the Aeropac version:
http://www.aeropack.net/webstore/product.asp?productid=349346352565805

Anybody have any experience with them?

Get the aeropack, you will not regret it. The lip is thin enough that you can use the kaplow clips to retain the adapter and the motor with ease, and you never have to worry about a glue joint failing with a hard hitting motor.

[Wayco]

WOW!!! Do you have to make it so complicated. griping about no thrust ring? I mean cmon. You cant use trim tape, need 1/2" masking tape. I have been using the loc adapters for years. I cut them in thirds and get 3 out of them.It is not lame, its the easiest and best out there for the money. And whats wrong with it not fitting? How often to you have to peel a D12 to fit? While I will admit not alot as of recently, but it was regular practice a few years ago. So you peel a few layers of paper off, beats having to sand it to fit. OK, My rant is over...enjoy your regularly scheduled forum.

WOW! I don't think I have ever had anyone over react to my comments quite like you just did Jim! Nothing complicated about wrapping 1/4" trim tape to an adapter, it's a lot like wrapping 1/2" masking tape actually. The difference for me is that the smaller tape makes the adapter fit into my Aeropac and Estes 29mm motor retainers. And it seems to be working just fine for the few flights I have made with it. Can't say I have ever peeled a D12 to get it to fit, (isn't that like altering a motor?) but I'm probably a relative novice with only seven years in the hobby. Probably haven't flown nearly as many D12's as you. But I will take your advice and enjoy my regularly scheduled forum. That's about the only good advice I found in your post.

Get the aeropack, you will not regret it. The lip is thin enough that you can use the kaplow clips to retain the adapter and the motor with ease, and you never have to worry about a glue joint failing with a hard hitting motor.

Thanks TerryG, that's the kind of advise I expect on this forum, but you probably aren't a Tripoli Prefect are you?
As far as the LOC adapter is concerned, I like qquake2k's idea, cut a lite ply centering ring and glue it to the end. THAT Jim has plenty of good advise.

[cavecentral]

I use 1/2 or 3/4" tape and friction fit ones that small. It is how we did it 20 years ago, and still works today. I see the 1/4" for aeropack with something to strengthen it. I think I'd rather cut a 1/4" plywood ring and epoxy it on though if you needed it to be thin.