School Project: HELP!

Anything educational to do with Rocketry and Space (This is for little and big kids ;))

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BethanyGrace
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School Project: HELP!

Postby BethanyGrace » Wed Mar 07, 2018 2:46 pm

I am in Year 10 at school and have been doing a project on rocketry research and I need to have a physical element. I was thinking of purchasing a MFR (My First 'Rocket) with a C6-5 motor. I'm fairly new to the subject but I need to relate it to math in some way. I was thinking of mapping the parabolic curves and relate that to algebra and all that fun stuff. also make a video montage of the launch in slow motion would be quite good fun I think. Has anyone flown this rocket before? how much land do I need to be able to launch it? need help as soon as possible thanks guys!

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SpaceManMat
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Re: School Project: HELP!

Postby SpaceManMat » Wed Mar 07, 2018 6:30 pm

Hi Bethany, welcome to the rocketry forums.

For the math the dominating forces are Thrust and Gravity. You can find out details about a C6-5 motor here https://ausrocketry.com.au/motors/singl ... 6-5-5.html it’s probably easiest to use average thrust and the burn time for your maths assignment.

Unlike thrust gravity is always acting on the rocket so you must take this into acount during both the thrust stage of flight as well as the coast stage of flight. Normally when the rocket reaches apogee we use a parachute to come down slowly so you possibly want to stop your calculations at that point, but for the full parabola you could see when it would hit the ground if the parachute failed.

The equation Force = Mass x Acceleration is going to be very useful.
From the above you can see that you will also need to know what the mass of your rocket is, typically for a C6-5 your rocket would weigh in at around 70-100g.

Oh and if you haven’t done so already you’ll also need to find out what acceleration due to gravity will be.

Hope this helps you start.
Matthew
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

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SpaceManMat
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Re: School Project: HELP!

Postby SpaceManMat » Wed Mar 07, 2018 6:47 pm

Also, I’ll refer https://ausrocketry.com.au/model-rocket-safety-code this lists the minimum feild sizes. If there is wind you’ll definitely a bigger site.

I omitted talking about drag as this is probably beyond what your teacher expects, but needless to say this will mean that your calculations are higher than real life. As will wind and launching at a non vertical angle etc.

Oh and the weight for an MFR is listed on the web page.
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

BethanyGrace
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Re: School Project: HELP!

Postby BethanyGrace » Thu Mar 08, 2018 2:39 pm

Thank you so much for your reply I really appreciate it. I had a plan to map the parabolic curves but didn't consider how I would do it or track the height and so on. Do you have any ideas on how i would do this for a reasonable price?

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lorstin
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Re: School Project: HELP!

Postby lorstin » Thu Mar 08, 2018 3:18 pm

Hi Bethany, try downloading a program called Open Rocket (it's free 8) ). You will be able to run all sorts of simulations for your rocket - it will give you a good idea if your calculations are on the right track.
caveat emptor

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SpaceManMat
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Re: School Project: HELP!

Postby SpaceManMat » Fri Mar 09, 2018 9:19 am

If you want to know actual altitude acheived then you would need an onboard altimeter such as the Altimiter 3 https://ausrocketry.com.au/altimeterthree.html which can show you altitude vs time graph that will have the parabolic curve on it (or at least half of it - up until the chute come out). They are however expensive and out of stock. Altimiter 1 only shows max altitude and 2 gives some additional performance details. As Lostrin says Open Rocket will allow you to simulate your rocket and can produce the previously mentioned altitude vs time graph.
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

Kryten
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Re: School Project: HELP!

Postby Kryten » Sun Mar 11, 2018 2:00 pm

Lots of ifs:
If you have access to a large enough field for a C6 motor
If you can correctly position a video camera you may be able to record the flight to just beyond apogee (before the parachute deploys), which may allow you to plot the parabola and calculate (roughly) its equation.
A lower altitude flight would be better for this, so a motor such as a B6 may be preferable.

If you really want to get into the maths, it is possible to calculate the theoretical altitude based on motor thrust and gravity - but drag is a big factor. To do it properly, you would also need to include this aspect in your calculations. This is a lot more complex (but is doable)

A simpler experiment would be to simply calculate the altitude by trigonometry. A 2-station system is much more accurate than a single station.

You could confirm the rocket's actual altitude by using a simple altimeter such as the AltimeterOne.

BTW, in which state are you based?
"Pub, ah yes. A meeting place where people attempt to achieve advanced states of mental incompetence by the repeated consumption of fermented vegetable drinks" (“Timeslides”)

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Happy Heyoka
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Re: School Project: HELP!

Postby Happy Heyoka » Tue Mar 13, 2018 10:38 pm

lorstin wrote:Hi Bethany, try downloading a program called Open Rocket (it's free 8) ). You will be able to run all sorts of simulations for your rocket - it will give you a good idea if your calculations are on the right track.


Also: there's the "Open Rocket Technical Documentation" (just Google that phrase)

It has the actual math used in the simulations - been a while since I did year ten but calculus involved is mostly straightforward; things like the Barrowman method for stability calculation involve no calculus at all.
Ha ha ha ha ha! You can't fool me! There ain't no Sanity Clause!
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