The graphs make sense, the numbers on the motors don't.. (If they add the N equivalent to the graphs, that might help correlate the two..) All Aerotech motors come with a thrust curve graph..
Blackbrandt is absolutely right. All I'm saying is mass and weight are too easily confused when talking about pounds. When's the last time anyone reported reported the mass of his/her rocket in slugs?
In retrospect, maybe the best lesson from this thread is "Don't trust anyone from Maryland." (Though maybe I'll meet some of you MDRA guys next year at LDRS.)
That's exactly how i do every single one of my conversions. Easiest way to make sure that you're never going to miss a single piece.We once had an argument at the office lasting approximately two hours over whether to convert metric tons to pounds force or pounds mass.
The secret to calculus is that it's all about areas and slopes. Sure, we dress it up with fancy words like integral and derivative, but that's just code. An integral is the area under a curve. A derivative is the slope of the curve. So if you have two thrust curves, you can tell pretty much at a glance which one has the most area under the curve and will likely send your rocket further. That's not 100% true, since a super short burn (eg F120) will get your rocket going really fast leading to higher drag and a lower flight, but it's close enough.
Unit conversions are always messy. I used to think my co-worker was overdoing it when he laid out every conversion in a line and then crossed out units above and below until he had the units he was looking for. Then I realized he got them right every time.
Unit conversions are always messy. I used to think my co-worker was overdoing it when he laid out every conversion in a line and then crossed out units above and below until he had the units he was looking for. Then I realized he got them right every time.
https://en.wikipedia.org/wiki/Metrication
So, only three countries seem to use the Imperial system, the US being the biggest user.. All others have converted, or in the process of.. (It's an interesting read!)
In Canada, we're ambidextrous because we deal with the US on every level, daily! So we can (mostly!) convert Km to miles, Gallons to Liters, pounds to Kg, etc.. The various jobs I've had (mech design) have been either metric or imperial measurements (mostly Imperial, due to the US market; selling to, and parts / supplies from).
Although I must admit, I do find it funny that the US is a hold-out for a system not readily used outside N. America..
Our form of government doesn't allow changes to be forced as in some countries, and schools here teach the metric system but dont use it, nor does the construction industry, transportation industry or a host of other industries here. Until the schools and businesses change metric will not be a standard in the US.
One thing I wanted to mention: The larger the number after the letter does not (always) equate to a higher attitude. Some think the bigger the number (after the letter) the higher it'll go..
Do a simulation, look at the numbers. A longer push at a lower thrust can get higher than a shorter initial push at a higher thrust..
(I recently mentioned I got a pretty good launch on a G64. I got a suggestion to try a G80. I will try, but my sims show I'll loose about 200'..)
Drag is a drag, man.
Otherwise we would never get our rockets back. :grin:
We'd be okay thanks to gravity.
-- Roger
Looks like I missed a lot of units as options: "my 1-hand rocket flew to 2 leagues."I prefer to measure speed in 'furlongs per fortnight'....
Great thread.... I prefer to measure speed in 'furlongs per fortnight'....
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