Timeline for What speed and altitude can I reach with a primitive sugar rocket?
Current License: CC BY-SA 4.0
7 events
| when toggle format | what | by | license | comment | |
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| Jun 15, 2018 at 15:00 | comment | added | Hobbes | Drag will be more of a factor in these small rockets than in large ones due to the square/cube problem (lots of surface area compared to internal volume/thrust). | |
| Jun 15, 2018 at 14:59 | history | edited | Hobbes | CC BY-SA 4.0 |
added 6 characters in body
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| Jun 15, 2018 at 14:52 | comment | added | olegst | I've just done a simulation in OpenRocket, for an average model engine fitting in 15 by 3 cm thick cardboard casing it gave me 0.94M speed, 900 m apogee. Something is wrong here, isn't it? | |
| Jun 15, 2018 at 14:23 | comment | added | MSalters | ln(m0/mf)=1, per engineering standards. Also Isp=100 and g=10. Now ln(m0/mf) means m0 = e* mf, which means the fuel fraction is somewhere near 2/3. With 2 digits precision, it drops to 60% fuel fraction. | |
| Jun 15, 2018 at 14:15 | comment | added | Hobbes | what mass fraction did you use? Sugar rockets don't usually get a 95% mass fraction... | |
| Jun 15, 2018 at 14:14 | comment | added | MSalters | So ignoring air resistance you're looking at >1000 m/s. That's very much supersonic. That in turn means you certainly can't ignore air resistance. | |
| Jun 15, 2018 at 13:57 | history | answered | Hobbes | CC BY-SA 4.0 |