TahoeGator
Member
- Joined
- Dec 25, 2017
- Messages
- 11
- Reaction score
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Hello and happy holidays!
In my (perhaps mad) genius I devised and built a rocket to launch my daughter's "Astronaut Barbie" per the attached picture. I am curious if it will work!
Reading posts on this forum, my first main concern was having enough power and enough altitude, but after running OpenRocket now my main concern is velocity off of the rod, which OpenRocket shows as 8.1 m/s.
The rocket:
standard BT70 tube with pre-cut slots for 3 fins; clear BT70 to hold Barbie; and a PNC-56A (BT-70) nose cone
rocket length is 40 inches; the CG (with the Barbie onboard) is about 25 inches from the nose cone tip
weighing it without a motor on my mom's kitchen scale suggests the rocket (no motor) and Barbie combo weigh about 10 oz.
with an Estes F15-8 motor, the weight is about 14.2 ounces...so perhaps it will be about 14.5 with chute and wadding
OpenRocket:
my first time using a simulator, I tried to create a simple setup to approximate the actual rocket
I got put in the dimensions, fins, etc., and got the weight and CG pretty close to my actual measurements
Simulation with F15-8:
Velocity off rod: 8.1 m/s
Apogee: 344 m
Optimum delay: 6.99 s
Time to apogee: 9.41 s
Regarding my first anxiety, that the 8 second delay on the F15-8 would be way too long, at least it doesn't look like it will hit the ground before deployment! But the 8.1 m/s velocity off the rod seems below other posts I've seen suggesting 15 m/s. I am using a standard Estes Max launch pad, which I measure as having a 34 inch rod.
I simulated two other motors...
E16-6:
Velocity off rod: 9.94 m/s
Apogee: 215 m
Optimum delay: 5.36 s
Time to apogee: 7.42 s
D12-3:
Velocity off rod: 10.6 m/s
Apogee: 74.4 m
Optimum delay: 3 s
Time to apogee: 4.63 s
...my preference is to run the bigger F motor for the higher altitude, but the others don't get that much higher velocity off the rod anyway.
I am limited to these motors because I have them on-hand here at my parents' house for the holidays (where all my rocket stuff is kept) with the intention to give it a go because we are only here once or twice a year, so it's make due with what we have.
The simulator gives a "green ball" next to it, though it does have a red "!" which it gives for having a high rate of speed (20.5 m/s) at deployment.
Would welcome any opinions
In my (perhaps mad) genius I devised and built a rocket to launch my daughter's "Astronaut Barbie" per the attached picture. I am curious if it will work!
Reading posts on this forum, my first main concern was having enough power and enough altitude, but after running OpenRocket now my main concern is velocity off of the rod, which OpenRocket shows as 8.1 m/s.
The rocket:
standard BT70 tube with pre-cut slots for 3 fins; clear BT70 to hold Barbie; and a PNC-56A (BT-70) nose cone
rocket length is 40 inches; the CG (with the Barbie onboard) is about 25 inches from the nose cone tip
weighing it without a motor on my mom's kitchen scale suggests the rocket (no motor) and Barbie combo weigh about 10 oz.
with an Estes F15-8 motor, the weight is about 14.2 ounces...so perhaps it will be about 14.5 with chute and wadding
OpenRocket:
my first time using a simulator, I tried to create a simple setup to approximate the actual rocket
I got put in the dimensions, fins, etc., and got the weight and CG pretty close to my actual measurements
Simulation with F15-8:
Velocity off rod: 8.1 m/s
Apogee: 344 m
Optimum delay: 6.99 s
Time to apogee: 9.41 s
Regarding my first anxiety, that the 8 second delay on the F15-8 would be way too long, at least it doesn't look like it will hit the ground before deployment! But the 8.1 m/s velocity off the rod seems below other posts I've seen suggesting 15 m/s. I am using a standard Estes Max launch pad, which I measure as having a 34 inch rod.
I simulated two other motors...
E16-6:
Velocity off rod: 9.94 m/s
Apogee: 215 m
Optimum delay: 5.36 s
Time to apogee: 7.42 s
D12-3:
Velocity off rod: 10.6 m/s
Apogee: 74.4 m
Optimum delay: 3 s
Time to apogee: 4.63 s
...my preference is to run the bigger F motor for the higher altitude, but the others don't get that much higher velocity off the rod anyway.
I am limited to these motors because I have them on-hand here at my parents' house for the holidays (where all my rocket stuff is kept) with the intention to give it a go because we are only here once or twice a year, so it's make due with what we have.
The simulator gives a "green ball" next to it, though it does have a red "!" which it gives for having a high rate of speed (20.5 m/s) at deployment.
Would welcome any opinions