54mm Alternative?

I have two 4" rockets that are being worked on. They both have 54mm MMTs. I like the sim for the J350, and I know I can use a motor adapter, but I want to fly it on a 54mm motor. What's a good equivalent alternative to the J350 but in a 54mm motor?

j275

The J430 is a ton of fun if you are interested in the Other Side. Otherwise yes it sounds like the J275 is your best bet.

I am a big fan of the J210 and was going to recommend that, but did not realize the J350 burned so fast.

+1 for sure!

jimzcatz said:

j275

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JD

Trying to stay under 4k for my cert flight. The J350 shows about 3800'. And RockSim has been showing high compared to the actual flights. I may end up going with the motor adapter and using the J350, I just felt the 54mm MMT deserved a 54mm motor.

Have you tried running sims on thrustcurve.org to see what options are available?

Worsaer said:

Have you tried running sims on thrustcurve.org to see what options are available?

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Well the rockets are not complete yet. I can only sim by approx weight. I've only used thrustcurve.org for motor files and to see what motors have the capability to fly. Never tried anything that could show me more on there.

You could also go with the J250W DMS. It's the single use equivalent to the J275W RMS.

pyrobob said:

You could also go with the J250W DMS. It's the single use equivalent to the J275W RMS.

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Do you have any of these? Mine are still back ordered.

Kruegon said:

Trying to stay under 4k for my cert flight. The J350 shows about 3800'. And RockSim has been showing high compared to the actual flights. I may end up going with the motor adapter and using the J350, I just felt the 54mm MMT deserved a 54mm motor.

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If that motor seems perfect, it is probably time to invest in one of the nice 54/38 adaptors. I have the Aeropack version and use it constantly. It is definitely my single most used rocket item, either in a rocket or lent to another person at every single flight I attend.

I'm investing in a lot of peripheral items right now. L2 has shown me that I am woefully unprepared in equipment compared to L1.

Something else my experiences are teaching me is that thrust profile and burn time are not, in and of themselves alone, a single gauge to compute a rocket's performance.

Average thrust, initial thrust, thrust taper, burn time, weight, fins, length, diameter, etc. they all have to come together in a near symphonic balance to achieve a perfect flight to a specified altitude range.

The days of the C6-5's were simpler. If the rocket balanced, you flew it. Similar views all the way through G's. That little jump to HPR truly changes the hobby from what we did as children.

I've developed a nice understanding of H's now. Still learning I's. J, K, and L will be a while to get down without constant cheat sheets. But I'll get there.

Sounds like the J275 is the weapon of choice. I'll play around with the sims and see where that takes me. I figure I'm 2 months away from having my L2 bird completed. Should have plenty of time to get the details figured out.

Thanks for the input everyone.

You might try the J1299. Nice straight boost, less walking to recover your rocket. If your rocket is fiberglass, use a smaller chute to also reduce your walk to recover.

Unfortunately no. They are both cardboard. Who do think I am? Jed Clampett?

Kruegon said:

Unfortunately no. They are both cardboard. Who do think I am? Jed Clampett?

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Jed Clampett prefers cardboard.

While not exactly "just like a J350 only 54mm", these are THE two coolest 54mm/J motors I've flown or witnessed:

CTI J-145 Longburn Skidmark. I simply love longburns, and this one is spectacular. This motor captured my attention like no other in 2015.

Gorilla J-450 Blacklight. Another sparky, and another spectacular bunch of AP on fire.

J motors are something of a odd hole in my launches. For whatever reason, I either seem to be flying H/I motors or K/L motors; and J's get passed over. It's purely coincidental as far as I can tell, and I've got no particular conscious bias against J's. I just don't seem to fly many of them. But when I do, and they are the motors I've described above, I love 'em.

Anywho, sim these two motors for the rockets you have in mind. If they look good in the sims, I promise you they will look GREAT in the sky.

s6

stealth6 said:

While not exactly "just like a J350 only 54mm", these are THE two coolest 54mm/J motors I've flown or witnessed:

CTI J-145 Longburn Skidmark. I simply love longburns, and this one is spectacular. This motor captured my attention like no other in 2015.

Gorilla J-450 Blacklight. Another sparky, and another spectacular bunch of AP on fire.

J motors are something of a odd hole in my launches. For whatever reason, I either seem to be flying H/I motors or K/L motors; and J's get passed over. It's purely coincidental as far as I can tell, and I've got no particular conscious bias against J's. I just don't seem to fly many of them. But when I do, and they are the motors I've described above, I love 'em.

Anywho, sim these two motors for the rockets you have in mind. If they look good in the sims, I promise you they will look GREAT in the sky.

s6

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The J145 is a huge crowd pleaser. I think vendors have a tough time keeping them in supply.

I though it sounded weird, since I usually associate long burns with low weight performance rockets, but when I saw it in person it was fantastic.

Yeah. No CTI motor cases. I fly AT hardware. Maybe I'll try CTI or Loki one day. For now, I stick with what I know and have.

jimzcatz said:

j275

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Jim and JD are spot on. I did exactly what you're thinking 10+ years ago when I got my L2. I love love love the J275, J415, K550 family. They have a longer burn and waaaay more smoke and yellow fire. J350 is just barely a J. J275 gives you're an extra 20% or so.

J275 > K350 one hundred percent of the time. You won't regret choosing the J275.

I too...... got my L-2 on a J-275...motor eject no less! Binder 4in. Galaxy went to 3800ft.
That was 12 years ago, till this day the 852 AT case is still my most used.
There is even a long burn blue thunder for it, along with the white lightning long burn version.
I keep the case loaded with something at every launch, too windy to go high, I use this & still fly!

It will take a light 4 in rocket [4-6lb] to 4500-4800 ft. on the J-275
Yet will fly a heavy glass 4 in [12-14lbs] to 18-2200 ft using the red J-315 in same case.
Fabulous on smaller fields with low waivers.

Lots of loads= lots of fun. Very versatile little motor....this is.

The big bad here is that my normal field only has a 3k waiver. Sucks. We're trying to get a new field. Not many options in the area for that club. So they end up having to be very heavy L2 rockets. And L3 is right out the door there.

Same as Jim. I used the J275 on my L2 flight back in 90 something in a scratch built 6" Big Bertha. It's been one of my favorite motors and most used cases ever since. This will likely give you more altitude than the J350 just due to total thrust. That has been my experience in flying the same rocket on these two motors.

I was thinking the J250 Black Max reload should give you closer to the same altitude as the J350 although take longer to get there. Watch the wind if you really need that kick off the pad though. Two cents from me.

Kruegon said:

Trying to stay under 4k for my cert flight. The J350 shows about 3800'. And RockSim has been showing high compared to the actual flights. I may end up going with the motor adapter and using the J350, I just felt the 54mm MMT deserved a 54mm motor.

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That is one option. Another option is to keep conservative with a 38 mm motor. Get the certification. Then load in a not so conservative 54 mm motor and have some fun. That is what I did anyway. My first five hpr motors were H, I, J, K, L. H and I were done on L1 cert day. J, and K were done on L2 cert day. Good luck with your cert.