The vehicle is 100% hardware complete.
We weighed it and we are at least 10% under our target weight!!!!!!!
I'm not going to publish the weight until I can repeat the measurement, with a better calibrated scale,but this gives us significant performance margin for reaching 180 seconds!
More details:
The target weight with payload was 326 lbs.
The target empty weight was 271 lbs
The actual empty weight 230 Lbs.
My actual empty weight is 15% under Budget!!!
In order to do the 180 seconds I need a realized in flight ISP of ~152
As John Carmack rightly points out it won't be as high as I expect or wish.
The theoretical ISP for the pressures and fuel combination I'm using is 227
So I need to realize 66% of theoretical.
This is with tanks 90% full.
If I go to tanks 97% full I need an ISP of 145
2 comments:
Congratulations!
One of the hardest parts to come up next: getting reliable and simultaneous ignition for all engines and stable hovering...
We've seen the possible difficulties from Mastens updates.
Best of luck, and hope to see you competing in XPC!
A picture of the complete vehicle would be nice...
(I hope/guess you'll be doing the flight tests on a tether... :)
Just a warning -- your in-flight Isp isn't going to be what you think it will be...
John Carmack
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