morlock
Well-Known Member
- Joined
- Jun 18, 2014
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Last year I bought a pack of Estes E9 motors to put in my two stage Fission rocket (the orange-and-black rocket in my avatar). I found out, much to my dismay, that this may not be a motor that is easy to find a good rocket for. It was my mistake creating a two-stage rocket that uses an E12-0 and then an E9-6. The motors plus the rocket were too heavy and after a LONG flight (2 seconds of booster, 3 seconds or second stage plus 6 seconds before deployment), the rocket was way over in a corn field where I couldn't find it (I WILL put a beeper in my next flights).
So, after that incident, I thought about the E9 some more and I think maybe it is a difficult motor to accomodate. It weights ~60grams, so to have a 10:1 thrust to weight ratio, you need 6 Newtons, or two thirds of its power, ONLY TO LIFT THE MOTOR. This means building an entire rocket around it that weights only 30 grams without the motor. Allowing a 5:1 ratio, which is too low where I fly because there is almost always 10-15km/h of wind (~3-4.5 m/s) and I do not have a 4 foot launch rod (I may get a rail later), means 120 grams for the rocket. Again, this is not very realistic, so maybe a maximum of 80 grams for the empty rocket.
Are there good kit choices for the Estes E9? Otherwise, making the lightest rocket with good fin area is the option, but it looks like it reduces the options for design.
What are your thoughts on the E9 and what to fly with it?
So, after that incident, I thought about the E9 some more and I think maybe it is a difficult motor to accomodate. It weights ~60grams, so to have a 10:1 thrust to weight ratio, you need 6 Newtons, or two thirds of its power, ONLY TO LIFT THE MOTOR. This means building an entire rocket around it that weights only 30 grams without the motor. Allowing a 5:1 ratio, which is too low where I fly because there is almost always 10-15km/h of wind (~3-4.5 m/s) and I do not have a 4 foot launch rod (I may get a rail later), means 120 grams for the rocket. Again, this is not very realistic, so maybe a maximum of 80 grams for the empty rocket.
Are there good kit choices for the Estes E9? Otherwise, making the lightest rocket with good fin area is the option, but it looks like it reduces the options for design.
What are your thoughts on the E9 and what to fly with it?
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