Rocketry Optimization

Seen something that has been extremely useful in the rocketry world? Post it here and share your sources.

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jhurst7
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Rocketry Optimization

Postby jhurst7 » Fri Jul 01, 2016 8:04 pm

Hello again,

Do you guys have any tips for optimizing rocket design i.e. tailcones, fin shapes.
Any help is much appreciated.
Thanks

-James
L1- AMRAAM 2- H54

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SpaceManMat
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Re: Rocketry Optimization

Postby SpaceManMat » Fri Jul 01, 2016 9:59 pm

James,

What do you want to optimise? Altitude, velocity, stability, size, weight , other?

Open Rocket, RocSim and RasAreo can help you with this.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

jhurst7
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Re: Rocketry Optimization

Postby jhurst7 » Sat Jul 02, 2016 8:32 am

SpaceManMat wrote:James,

What do you want to optimise? Altitude, velocity, stability, size, weight , other?

Open Rocket, RocSim and RasAreo can help you with this.


I spoke to Blake about some high altitude rockets and currently I've got a stability margin of 2.24. However, this has cost me around 6 km. I was wondering if anyone had any tips on improving the height while maintaining the stability.

Thanks.
L1- AMRAAM 2- H54

martymonsta
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Re: Rocketry Optimization

Postby martymonsta » Sat Jul 02, 2016 8:45 am

Hi James. The perfect one size fits all design for a rocket doesn't exist, and even if it did I wouldn't want to rob you of the joy that comes from discovery. However the answers that you are looking for are already here on the forum. There are build threads for rockets that hold impulse class records and have survived some of the most aggressive motors available.

The guys that are really pushing the envelope are top blokes that will share ideas and help with skills, provided that you are helping yourself. So maybe start with going to the scratch built section of the forum and have a look at some of the longer threads. I hope that helps.

Marty
Many years ago the great British explorer George Mallory, who was to die on Mount Everest, was asked why did he want to climb it. He said, "Because it is there."
Well, space is there, and we're going to climb it

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SpaceManMat
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Re: Rocketry Optimization

Postby SpaceManMat » Sat Jul 02, 2016 10:17 am

jhurst7 wrote:
SpaceManMat wrote:James,

What do you want to optimise? Altitude, velocity, stability, size, weight , other?

Open Rocket, RocSim and RasAreo can help you with this.


I spoke to Blake about some high altitude rockets and currently I've got a stability margin of 2.24. However, this has cost me around 6 km. I was wondering if anyone had any tips on improving the height while maintaining the stability.

Thanks.


If your after altitude, then I would look at getting a minimum stability of 1.5 - 1.25. You'll need to be very careful here as stability changes during the flight. If your down by 6km then it sounds like your going pretty high and fast so 1.5 may be more appropriate (I don't know cause I'm not sure what your planning and building.

The most important aspect is to minimize your frontal area, this means we are talking about minimum diameter rockets or sub-minimum diameter as Nic puts it. Again not really sure what you are planning or have realized this.

Each rocket will have an optimal weight, you need to build close to this. OR etc, will help you with this.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

jhurst7
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Location: Brisbane, Australia

Re: Rocketry Optimization

Postby jhurst7 » Mon Jul 04, 2016 8:17 pm

I've got an idea for a rockoon design and a balloon manufacturer gave me an estimate of around 57 000ft as a burst altitude and so I've got an open rocket design that uses an O-8000 motor to get to around 101 000m. I was just trying to maximise that so I could maximise the payload. It has a stability margin of around 2. Could I maybe cut that down if it stays stable on open rocket and are they any ways to maximise this.
L1- AMRAAM 2- H54

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OverTheTop
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Re: Rocketry Optimization

Postby OverTheTop » Mon Jul 04, 2016 9:13 pm

Hi James. Ambitious project.

Amongst other things, note that you will need to have some sort of spin stabilisation (or other method) to keep the rocket flying straight. Launching from 57k' there is not much air to provide force moments on fins, so fins won't be much good to you. I am guessing calculating a static stability margin is a pointless exercise. :?

Pressure at sea level : 1013 hPa
Pressure at 60000 feet: 0.22 hPa (factor of 4600 less)

Looking at actual density, it is only a factor of 3955 thinner :wink:

Good luck with the project. I assume you are planning earlier flights for experience and proof-of-concept for systems etc?

One thing to watch out for, and we can all suffer from this. You don't know what you don't know. Ask people who have done what you are trying to do (or similar) and try to learn from their mistakes. :D
TRA #13430
L3
"Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

jhurst7
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Re: Rocketry Optimization

Postby jhurst7 » Tue Jul 05, 2016 10:21 am

I have a fin cant of 1° so the spin stabilisation is there, and yes I will be doing other projects. I'm currently working my way up through the AMRS levels, its only a hypothetical at this point. And I will do earlier flights that aren't from 57k' once I get my L3.
L1- AMRAAM 2- H54


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