Understood. I've lost rockets my last three times out. Not happy about it. Living here in Chicago I have limited room to recover. I have to head up to Wisconsin to fly anything over about 500ft.
Flying Estes Maniac, kit 2091, on an E9-4?
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Understood. I've lost rockets my last three times out. Not happy about it. Living here in Chicago I have limited room to recover. I have to head up to Wisconsin to fly anything over about 500ft.
If you are worried about CATOs, just check the date code on the motor against the Suspected Bad Motor List:
https://www.rocketryforum.com/threads/suspected-bad-motor-list.150501/
I've never had an E9 fail after I started checking the list.
https://www.rocketryforum.com/threads/suspected-bad-motor-list.150501/
I've never had an E9 fail after I started checking the list.
Thanks for all of the advice. The package card says the Maniac will even fly on a C5-3 (C5?) or a C6-3 with the optional EM-2050 (EST 3159) engine adapter. I have never seen a C5, but a C6 has maximum thrust of about 11.8 Newtons. A D12, which is also recommended, has maximum thrust of about 30 Newtons An E12 has maximum thrust of about 33 Newtons. Now, an E12 weighs 59 grams. A D12 weighs 46 grams and C6 weighs 24 grams (plus the small weight of the adapter. All three engines hit their max thrust in about .3 seconds.
Without being scientific about this, it seems to me that, if the rocket will fly on a D12, an E12 ought to be a safe bet, no? Either engine has plenty of initial oomphto get this 130 gram rocket off of the lanuch pad.
I will try it on a C6, D12, and an E12. If they all work, I will chance a 4th flight on the E9.
An E9 has a max thrust of only 19.5 newtons but a heft weight of 58 grams. Hmm. Must be for lighter birds, for a slow, realistic lift off.
Hmm. OpenRocket says the speed off the pad on a C6 is 27.7 ft/sec. That’s scary slow.
We will start with a D12-7 and experiment from there.
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Estes just re-introduced this motor, it had been OOP for quite a while.
001617 - C5-3 Engines - Estes Rockets
It's called the Super C, faster punch off the launch rod.
OpenRocket gives a danger, red exclamation mark when I simulate the Maniac on an E9-4. The sim says the spoed at ejection is too fast (89 ft/dec). The 4 second delay is too short.
The C6 does not have enough power to get that rocket off the pad safely. The C5-3 will lift it safely. Just make sure the rod is straight up. If it were me, I'd start with the C11-5 and go up to a D12-5 or D12-7.
I find it a bit nerve-wracking that the people who sold and packaged the Maniac back in the 90’s would list a C6 as an acceptable rocket motor when just eye-balling the thrust curve of a C6 makes us rocket kit consumers nervous. Didn’t they test the rocket on the C6 before listing it on the package as an acceptable motor?
It's not always clear how they come up with their list of recommended motors. Quite possibly they were using different criteria back then, but even today there are occasionally strange recommendations.
Fortunately for us we can very easily validate everything (especially rod speed) through thrustcurve.org and/or a sim program, and don't need to take the mfr recommendations as gospel.
I kind of like “slow, realistic” lift offs. But that means treading a fine line. One has to use a nice, long launch rod (mine is only 4 feet long), a light rocket, compared to total engine power, and a rocket motir that has enough initial thrust to get the rocket moving at at least 45 feet per second or do when it leaves the rod. Slow and realistic means keeping pad lift off speed near the minimum but not TOO slow. If there is significant wind, or if the model is only marginally stable, the slow, realistic lift off becomes a scientific demonstration of “unstable rocket flight”.
So the Saturn V, Space Shuttle, Ariane, Falcon, Soyuz, and other rockets, past and present, that have no fins or minimal fins, achieve stability how? Gyroscopes? Gimbaling the engines? Both? Something else?
heada
Well-Known Member
Nearly all large real rockets use gimballed motors. Look at sounding rockets for real rockets that use passive stabilization (fins)
Internet to the rescue:
https://space.stackexchange.com/que...ring-the-initial-slow-speed-portion-of-launch
Keeping the thrust vector pointed directly through center of gravity is the key to keeping the rocket stable at lift off. Gimbaling the engine(s) is just one of several ways to do that. Gimballing the engines is the method used by most modern rockets.
I assume that as the rocket gathers speed the aerodynamic forces on the (usually) long, thin rocket shape start to help with stability.
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Do any model rockets, say, a fancy, expensive, HPR rocket, use gimballed motors? That would be wild!
That makes sense. I think they are heavier or have more drag than your rocket, thus shorter delay.
heada
Well-Known Member
There used to be a kit you could buy to add a gimballed motor mount from BPS.Space. It used standard 29mm motor mount, 3D printed parts, servos and a control board. You had to use low thrust motors like the G12. Very much not cheap but very cool. Joe is a very smart guy. Search youtube for BPS.Space and you'll find his videos on design, build and flying a gimballed motor HPR rocket.
That would be incredibly cool!
I just checked it out at bps.space (did not know that ".space" was a top level domain). This is so cool!
OMG, you gotta see this:
https://bps.space/products/signal-r2
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I’ve had my E9 motors stored at room temperature, in an interior closet drawer for years. I’m hoping the hobby store owner and his shipper were as careful….
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I've flown that rocket on many D12-5s. It gives a great majestic liftoff with plenty of height and chance to get it back. Unless you have a very large field, on an E12 you risk losing it! Just sayin' 
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I'm nostalgic about that rocket...wish I still had one! I first got into rocketry when it first came out and was my first D powered rocket!
I first got into rocketry when it first came out and was my first D powered rocket!
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Back in the day, I always flew my Executioner on E9-4s for great flights before I ever knew of the failure rates! I remember flying many E15s too in my old Phoenix! Then I heard of their failure rates and then mine started failing...but they only blew fireballs through the nose cones without destroying the rockets!
I remember flying many E15s too in my old Phoenix! Then I heard of their failure rates and then mine started failing...but they only blew fireballs through the nose cones without destroying the rockets!
Take a video of the E9 launch and you won't have to worry about a Cato. Sandra at Estes might be amused if you ask for warranty replacement of a vintage rocket using a vintage E9. Afterall, there's no expiration date.
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