 # The RAS Formula

In the December 2018 issue of Sport Aviation / Experimenter magazine, we look at what we call the RAS formula. A concept for improving aircraft and engine reliability, while simultaneously lowering the operating cost.  December 2018 Loading... Taking too long? Reload document
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1. Fascinating concept! Thank you for explaining it. I’m having a hard time understanding the 3rd formula in figure 2, however. It says,
(new engine cost) – (value consumed) * (age multiplier) = sales price
Without an extra set of parentheses, this is a bit ambiguous. Does (age multiplier) adjust just (value consumed), or [ (new engine cost) – (value consumed) ] ? Put another way, does this equation mean:
(new engine cost) – [ (value consumed) * (age multiplier) ] = sales price
or
[ (new engine cost) – [ (value consumed) ] * (age multiplier) = sales price
?

If (age multiplier) adjusts (value consumed) only, then it serves to slow the drop in sales price with age, meaning the deal gets poorer and poorer as the engine ages. If it adjusts the difference [ (new engine cost) – (value consumed) ], then the deal gets better as the engine moves through the “target range” for engine age to sell the engine. That makes a lot more sense.

Could you clarify please? (And sorry if the the blog software removes all line breaks, this will be harder to read if they disappear.)

1. Post
Author

Jim,
This wis what was intended. [ (new engine cost) – [ (value consumed) ] * (age multiplier) = sales price

1. Thank you for the clarification. You wrote:

[ (new engine cost) – [ (value consumed) ] * (age multiplier) = sales price

which has two left square brackets but only one right square bracket. Did you mean:

[ (new engine cost) – (value consumed) ] * (age multiplier) = sales price

If so, then that makes intuitive sense, and jibes with your explanation. However, it’s a pity that EAA Sport Aviation didn’t include the square brackets, or something like them, in the printed article. Without them the equation they published doesn’t really say what I think you are trying to say.

2. Oops, I put a typo in my second equation. I put in two open square brackets and only one close square bracket. That second equation should read:

[ (new engine cost) – (value consumed) ] * (age multiplier) = sales price

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