Question on 24mm engines

Dee55

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What is the weakest 24mm engine? Reason I asked is because where I have to launch at u can't over fly it cause of losing a great rocket. I have a fave rocket I fly that requires C6-5 and iv launched on B engines and did pretty good. I have a full size mean machine and want to build her and fly I just wanted know the weakest 24mm . Lol sorry for the long story for just one question 😐
 

smstachwick

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Perhaps Estes C11. I don't recall any other 24mm C's.
Correct, it is a C11. It comes in 0, 3, 5, and 7-second varieties. They’re good for keeping hot rods like the Estes Goblin under control without having to mess around with adapters.

For information on commercially available rocket motors, visit ThrustCurve.org . John Coker ( @JohnCoker ) runs the site and he’s got a thread here dedicated to reporting bugs and suggesting improvements on that site.

What altitude do u think I'll get with a C11 in the mean machine?
I’d say 175 ft would be optimistic. Try it on a C11-3 and see if you get the chute out before ground impact. Upgrade to D12-5 power if you’re confident you’ll get it back.
 

JohnCoker

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What is the weakest 24mm engine? Reason I asked is because where I have to launch at u can't over fly it cause of losing a great rocket. I have a fave rocket I fly that requires C6-5 and iv launched on B engines and did pretty good. I have a full size mean machine and want to build her and fly I just wanted know the weakest 24mm . Lol sorry for the long story for just one question 😐
Here are the 24mm model rocket motors available:

By "weakest", you probably mean lowest total impulse, which would indeed be the C11.
 

neil_w

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Is using a 18mm engine (like a Super C) with an adapter an option?
It's *always* an option isn't it? A C5-3 is probably a decent possibility, although not necessarily any better than a C11 (I don't think). I would say a QuestJet D20 might work as well, but not sure if the minimum 4 second delay is still going to be too long.

But to the OP: as I've said before and will say it again: there's no reason to play guessing games when there are free tools at your disposal to do the work for you in a more rigorous way. If you're not yet up to speed on OpenRocket, you can get a very good first approximation from the easy-to-use tools on thrustcurve.org. Take a few minutes to get to know them and use them and you will have leveled up.
 

Back_at_it

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I have some apogee numbers from a couple of altimeter flights. Keep in mind that my Mean Machine is a little bit heavier than normal as it has 30" stuffer tube and a baffle but I did leave out that silly plastic coupler. Mine weights in at 6.45oz without motor.

D12-3 I have recorded 446ft and 493ft. I feel like the ejection was just a touch early.
D12-5 I have recorded 518ft, 523ft and 540 ft. Ejection was just about perfect.

I ran a sim on my rocket using a C11-3 and it shows an apogee of 203ft but the ejection should be just about perfect. The motor should have enough thrust to get the rocket moving off the pad quickly enough. I'm showing 31.9 mph off a 48" rod.

As for the C5-3. It provides the thrust needed but I would be concerned with that small motor having enough energy in the ejection to actually pop the nosecone.

Honestly, the mean machine is such a big rocket, 500ft isn't a lot for it. I would recommend sticking with the D12-5 motor. I would only try the C11-3 on a dead calm, zero wind day. And if you are lucky enough to have a dead calm zero wind day then why not fly the D12.
 
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MidOH

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Mean Machines don't even go high. A 'lil Alpha smokes them.

Stick with a D12-5. There should be bigger fields down there. Why locked onto this little one?
 

Dee55

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Place I use to go u could launch anything , but the land was sold now I'm having go to a Jr high school football field and some trees and houses near by..and the county is pretty A Holes when it comes to flying rockets lol
 

smstachwick

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Place I use to go u could launch anything , but the land was sold now I'm having go to a Jr high school football field and some trees and houses near by..and the county is pretty A Holes when it comes to flying rockets lol
If they’re not nice about it, then you should look at getting written approval from the school before you head out to fly. Flying rockets without this approval is a good way to get the entire hobby shut down in your jurisdiction, especially if you damage something or hurt someone.
 

Dee55

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The school said I could even the city police department. But the county commissioner forgot her name she is well let's just leave it at that.. she knows the school gave me permission and the city cops don't care she has a bad rep on a lot of things. But I'm good there..just can't fly when people are in the grounds that's why I go early Sunday mornings around 6:30 AM.. besides around here I'm probably the only one in the whole county that flys model rockets
 

smstachwick

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The school said I could even the city police department. But the county commissioner forgot her name she is well let's just leave it at that.. she knows the school gave me permission and the city cops don't care she has a bad rep on a lot of things. But I'm good there..just can't fly when people are in the grounds that's why I go early Sunday mornings around 6:30 AM.. besides around here I'm probably the only one in the whole county that flys model rockets
Trying to decipher your writing…

The school suggested you email the police department for approval? And they gave you approval to fly as long as there aren’t people around?

If that‘s correct, that sounds like landowner approval and the cooperation of law enforcement to me. I would be surprised to see that cause problems.

Even so, I’d still bring a hard copy to the launch just in case. The person at the police department’s front desk may be clued in but a random officer who turns up responding to a call, or their own observations of your activity, may not be. If they have questions, show them your permit.

If they’re not having it, it’s best to pack up and leave. Qualified immunity is a nasty thing and they’re not shy about invoking it if you tick them off. You’re more likely to get somewhere by getting in touch with elected and appointed officials than a control freak with a gun.
 
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Sooner Boomer

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What altitude do u think I'll get with a C11 in the mean machine?
I wouldn't fly it on a C-11. Estes says the weight of the Mean Machine is 8.5 oz. A C-11 weighs an additional 1.18 oz, for a total of 8.68 oz. The max liftoff weight for a C-11 is 5.0 oz.
 

dhbarr

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I wouldn't fly it on a C-11. Estes says the weight of the Mean Machine is 8.5 oz. A C-11 weighs an additional 1.18 oz, for a total of 8.68 oz. The max liftoff weight for a C-11 is 5.0 oz.
Crucially, we see the d12 has an extra 8 newtons max thrust, but the c11 peaks around 70% of that.
 
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Back_at_it

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If you leave out the failure prone plastic coupler that comes with the current rocket and use a normal cardboard coupler you can save yourself about 1.6oz. I'm not sure where Estes gets the 8.5oz from as mine complete with stuffer tube and baffle is only 6.45oz.

Using OR, the C11 would lift it just fine but with plenty of scoot off the pad but I wouldn't try it in anything other than dead calm winds and it should really be launched off a 1/4" rod.
 

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I split my Mean Machine in half, used a 4" balsa bulkhead and saved significant weight. I set it up with dual parachutes.

Performance even on E12-6s is eh, meh, slow flight. The first E12 flight was at Red Glare a few months ago. Decently windy. Ascent was fairly slow, but strangely enough the rocket kind of coasted to apogee, didn't tip over or anything. Rocket stopped at the top in basically an upright position, then started dropping tail first. Thankfully the ejection was fine and it landed safely. I really want to try an E-composite but my regular fields are kind of iffy. Maybe if put in my new chute release I might get it back. :)
 

MALBAR 70

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I've flown my Custom Equinox ( a cousin of the Mean Machine ) on C 11's a few times, and well, let's just say it was a cringe worthy flight at best.
Stick with D12's, they give a much better flight.
 

Bill S

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I thought that was kind of interesting as mine does that as well pretty much every flight. I don't fly it on windy days so it's not too often that I see it arc over.
Wow, really? :) I'm glad to hear that I am not the only one this happens to. :)
 

neil_w

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From reading @Dotini 's threads regarding his Magnus-effect recovery rockets, I learned that rockets expressly designed to "back-slide" at apogee are made very long and skinny... basically just like a Mean Machine. My assumption is that the high moment of inertia causes it to resist turning too much at apogee.
 
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