RMS 40/120 different from all other cases?

Antares JS

Professional Amateur
TRF Supporter
Joined
Mar 5, 2020
Messages
3,200
Reaction score
5,485
Location
Eastern Shore, VA
I have found that a lot of the time, the 29/40-120 igniters fit through the nozzle and don't need to be installed before the motor is closed up, but I test the fit of the igniter tip through the nozzle before assembling, just in case. At the pad, I have to feel around a bit with the igniter tip to find the slot but that's not a big deal. The one thing I should note here is as of late I almost always fly G's in my 29/40-120, and I don't know if the nozzles for the E's and F's might have smaller throats.
 

loopy

Well-Known Member
Joined
Dec 13, 2009
Messages
4,736
Reaction score
149
I have found that a lot of the time, the 29/40-120 igniters fit through the nozzle and don't need to be installed before the motor is closed up, but I test the fit of the igniter tip through the nozzle before assembling, just in case. At the pad, I have to feel around a bit with the igniter tip to find the slot but that's not a big deal. The one thing I should note here is as of late I almost always fly G's in my 29/40-120, and I don't know if the nozzles for the E's and F's might have smaller throats.
I feel the same...I mostly fly F and G loads in this, but have never had a need to build the igniter into the motor during assembly. Sometimes I've had to with copperheads in the 24/40, but never with anything in the 29/40-120.
 

4regt4

Well-Known Member
TRF Supporter
Joined
Mar 11, 2022
Messages
489
Reaction score
264
Location
Southern Oregon
I have both the 24/40 and 29/40-120 cases. I like them, especially the 24mm. But there is a bit of a hole in the motor offerings. There is no real "mid-F". The 24/40 ends at 49.7NS, and the 29/40-120 picks up at 73Ns for the F52. I'm ignoring the F22, as it doesn't have enough oomph to give stable rod velocity for anything I have. The 24/60 offers some relief with motors up to 57Ns. But I'm not finding it worthwhile to spring for the 24/60 case just for a few use cases. So I supplement my reloads with the F67 (61Ns) single use, which happens to be non-Hazmat.

Hans.
 

DigBaddy

Well-Known Member
TRF Supporter
Joined
Feb 19, 2021
Messages
1,214
Reaction score
2,453
Location
SE, WI
I have both the 24/40 and 29/40-120 cases. I like them, especially the 24mm. But there is a bit of a hole in the motor offerings. There is no real "mid-F". The 24/40 ends at 49.7NS, and the 29/40-120 picks up at 73Ns for the F52. I'm ignoring the F22, as it doesn't have enough oomph to give stable rod velocity for anything I have. The 24/60 offers some relief with motors up to 57Ns. But I'm not finding it worthwhile to spring for the 24/60 case just for a few use cases. So I supplement my reloads with the F67 (61Ns) single use, which happens to be non-Hazmat.

Hans.

Totally with you on the lack of Mid-Fs for that case; and the F22 is not appealing. I enjoy the F20/23/42 and F52C SU motors; and cost/motor is about the same as what a reload would be.
 

smstachwick

LPR/MPR sport flier with an eye to HPR and scale
TRF Supporter
Joined
Jul 29, 2021
Messages
2,589
Reaction score
2,524
Location
Poway, CA
92D687D7-0B50-4D06-B352-4784F0CB00F7.png

You may disagree but I think this is pretty decent coverage of the range, especially considering the dearth of mid-Fs in general. I would agree if I didn’t consider single-use motors.

45FF306B-5600-4805-820B-46E9EFC32B2B.jpeg
 

4regt4

Well-Known Member
TRF Supporter
Joined
Mar 11, 2022
Messages
489
Reaction score
264
Location
Southern Oregon
This basically proves what we were discussing above. There is a big hole in the mid-F range for the 24/40 and 29/40-120. Thus the need to supplement with a SU, in my case I like the F67.

Hans.
 

waltr

Well-Known Member
Joined
Jul 17, 2021
Messages
1,163
Reaction score
688
Location
SE Pennsylvania
I have flown the F52T in a 29/40-120 case. Nice load except the Hazmat shipping, The SU F52C is also nice.

When we want to scare the kids in a demo flight we like the SU F67W.
 

wsume99

Well-Known Member
TRF Supporter
Joined
Feb 28, 2014
Messages
350
Reaction score
129
Location
Ohio
This basically proves what we were discussing above. There is a big hole in the mid-F range for the 24/40 and 29/40-120. Thus the need to supplement with a SU, in my case I like the F67.

Hans.
The hole pretty much disappears if you include the 24/60.
 

4regt4

Well-Known Member
TRF Supporter
Joined
Mar 11, 2022
Messages
489
Reaction score
264
Location
Southern Oregon
The hole pretty much disappears if you include the 24/60.
Like I said in Post #34:

"The 24/60 offers some relief with motors up to 57Ns. But I'm not finding it worthwhile to spring for the 24/60 case just for a few use cases. So I supplement my reloads with the F67 (61Ns) single use, which happens to be non-Hazmat."

Even with the 24/60, there is still a gap from 57Ns to 73Ns.
 
Joined
Dec 19, 2011
Messages
335
Reaction score
252
Location
Lebanon,IN
Yes, the 29/40-120 is a bit different in a sense, but it is a good first reload case. It was my first reload case. Of course, the manufacturers have all introduced new closure sets/spacers that permit the longer cases to use 1 or 2 fewer grains for the larger motors as well so now they are more like the 80-120 case.
 

4regt4

Well-Known Member
TRF Supporter
Joined
Mar 11, 2022
Messages
489
Reaction score
264
Location
Southern Oregon
It is tempting to get a 24/60 case, however, because it offers some different propellant types - like the Redline. Might be worth the price of entry just to see the red flame.

Hans.
 

wsume99

Well-Known Member
TRF Supporter
Joined
Feb 28, 2014
Messages
350
Reaction score
129
Location
Ohio
Like I said in Post #34:

"The 24/60 offers some relief with motors up to 57Ns. But I'm not finding it worthwhile to spring for the 24/60 case just for a few use cases. So I supplement my reloads with the F67 (61Ns) single use, which happens to be non-Hazmat."

Even with the 24/60, there is still a gap from 57Ns to 73Ns.

oops, yeah you did say that already

It would be nice if there were more options available in the 24/60. I find the 24/60 more useful than the 24/40 mainly because I build too heavy. Anything in the 24/40 either has too low impulse or not enough thrust for me.
 

dwinings

Well-Known Member
Joined
Jan 18, 2009
Messages
112
Reaction score
14
Ok, I'm going to admit to being a doofus when it comes to reloadable hardware. I'm still so new to this. However, it seems that the Aerotech RMS 40/120 case is a popular place to start learning, however, it appears that the 40/120 is different from all other reloadable hardware. The reloads for it are case-specific and even the forward and aft closures are case-specific and won't fit any other 29mm cases.... which is making my head spin.

All that said, how in general does this all work? It appears to me that the longer 29mm tubes are for higher power G and H reloads as I assume they take more "grains" and therefore are for flying 3000+ ft, which I am currently not planning for the next year or so.... SO, I'm looking to start with the shorter 29mm reloads since I don't want to go beyond F, although I may want to stray into "G" territory by the end of 2023 (or at least give it a try).

Anyhow, the 40/120 seems to be the place to start -- but the question is what makes this way to go, and/or is there a better option?
Here are my requirements:
#1) I want to start small -- this is going to work in both 1.6 diameter to 3" diameter rockets, using F power mostly.
#2) IF I want to go into "G", is this still the case to use or do I need something bigger?

I'm currently using single-use F motors in these rockets, but I'm thinking down the road I need to learn about this stuff as I'm hoping to try for L1 in 2024.

Thanks!
If you are not going above F the 40/120 case is the way to go. It more different reload options then any other case. I use mine more than any other reload case I and I have a lot, my casings range from 18mm all the way to 54mm, but I have not yet flown the 54mm casings
 

Joekeyo

Well-Known Member
TRF Supporter
Joined
Sep 12, 2019
Messages
759
Reaction score
702
Location
Sun City Center, FL
It is tempting to get a 24/60 case, however, because it offers some different propellant types - like the Redline. Might be worth the price of entry just to see the red flame.

Hans.
Red and green color are subtle below "H". As it was explained to me: Bigger motors burn a whole lot more at once.
 

bjphoenix

Well-Known Member
TRF Supporter
Joined
May 3, 2011
Messages
1,554
Reaction score
637
I have found that a lot of the time, the 29/40-120 igniters fit through the nozzle and don't need to be installed before the motor is closed up, but I test the fit of the igniter tip through the nozzle before assembling
I always test fit the igniter in while I was building. My reason is because different reloads had different length grains so if I fit the igniter in while building the motor I could be sure that the igniter head was positioned at the front end of the fuel grain. I would test fit the igniter through the nozzle and grain, fold the igniter around the end of the nozzle then take it out and carefully set it aside. Then after building the motor I could put the igniter back in and know that the igniter was positioned correctly.
 

4regt4

Well-Known Member
TRF Supporter
Joined
Mar 11, 2022
Messages
489
Reaction score
264
Location
Southern Oregon
I always test fit the igniter in while I was building. My reason is because different reloads had different length grains so if I fit the igniter in while building the motor I could be sure that the igniter head was positioned at the front end of the fuel grain. I would test fit the igniter through the nozzle and grain, fold the igniter around the end of the nozzle then take it out and carefully set it aside. Then after building the motor I could put the igniter back in and know that the igniter was positioned correctly.
A sharpie mark on the wire right where it enters the nozzle works well. And is simple.

Hans.
 

waltr

Well-Known Member
Joined
Jul 17, 2021
Messages
1,163
Reaction score
688
Location
SE Pennsylvania
Something else I do with loads for the 29/40-120 case that are less than full case length.
That is put a piece of masking tape across the top of the grain to close off the slot. This is the position the igniter at the top of the grain and not into the space between the grain and delay.
Some of the reload instructions say to do this but not all do.

Test fitting the igniter to ensure it can go through the nozzle is a good idea since sometimes the supplied igniter is too fat to fit. Just had this problem with a 29/180 case and G75FJ reload. The igniter will not fit through the nozzle.

This and that sometimes the igniter supplied is damaged is why I bought a QuickBurst ProCast pyrogen kit and started making igniters. Now I have various sized igniters where one will fit through the nozzle and spares in case an igniter burns and doesn't light the motor. I have given away a number of my igniters at club launches when a AT supplied igniter failed.
 

prfesser

Well-Known Member
TRF Supporter
Joined
May 7, 2017
Messages
3,074
Reaction score
4,118
Location
Murray, KY
I'm not certain how much of an issue the "hole" in the mid-F range is, in practice. I ran quick and dirty Open Rocket sims on the Estes Hi-Flyer XL with three different F motors. There are, of course, differences in performance but how big are those differences?

I couldn't do a screenshot so here's a summary. Going from baby-F to mid-F increases apogee by about 300 feet or 18%. Mid-F to full-F, a bit more than 400 feet, 23%. To me, a difference of 300-400 feet on a flight to 2000 feet isn't terribly significant unless you have a target apogee in mind; YOMV (your opinion may vary :))

The differences in average thrust and burn time undoubtedly have some effect as well, though I doubt those effects will be very large.

MotorTotal impulseApogee
F41-746 N-s1645 ft
F35-758 N-s1944 ft
F30-774 N-s2386 ft
 

gldknght

Well-Known Member
Joined
Jan 26, 2011
Messages
998
Reaction score
264
Location
The Edge of Nowhere
Not just that, but @heada has me thinking I should *also* get the 24mm reloadable as that could also lead to some extra excitement with my existing batch of 24mm rockets. But yes, I know what you are saying as I clearly see a 4" Zephyr and a 38mm motor in my future only 12 months or so down the road. But we'll see. Maybe I'll run out of money before that (although I understand they pay pretty good for a kidney these days).
I highly recommend getting the Zephyr. I have one and love it. It was very easy to build and you can use it for your Level 1 cert flight. It comes with a 38mm mount but it's easy to use a 38mm to 29mm adapter for less expensive motors. If the Zephyr is your first high power capable rocket, Apogee has video instructions making the assembly almost fool-proof.

 

4regt4

Well-Known Member
TRF Supporter
Joined
Mar 11, 2022
Messages
489
Reaction score
264
Location
Southern Oregon
I'm not certain how much of an issue the "hole" in the mid-F range is, in practice. I ran quick and dirty Open Rocket sims on the Estes Hi-Flyer XL with three different F motors. There are, of course, differences in performance but how big are those differences?

I couldn't do a screenshot so here's a summary. Going from baby-F to mid-F increases apogee by about 300 feet or 18%. Mid-F to full-F, a bit more than 400 feet, 23%. To me, a difference of 300-400 feet on a flight to 2000 feet isn't terribly significant unless you have a target apogee in mind; YOMV (your opinion may vary :))

The differences in average thrust and burn time undoubtedly have some effect as well, though I doubt those effects will be very large.

MotorTotal impulseApogee
F41-746 N-s1645 ft
F35-758 N-s1944 ft
F30-774 N-s2386 ft
I'm still a bit of a chicken over higher altitudes, given that most of my flying fields have trees or other hazards nearby. So my ventures into F motors is with bigger, heavier rockets, like my North Coast Bounty Hunter. In that, little Fs are basically unflyable (~300ft), mid Fs are comfortable (548ft), big Fs (822ft) need to be reserved for places with fewer trees. (These are altitudes actually reached.) So I'm flying mostly with the mid level F67. I have a couple venues that I go to maybe twice a year that can easily handle G class, but for anywhere local I need the mid level.

As you can see, the percentage increases for flying a big pig are considerably more than in your light weight example.

Hans.
 
Top