MyNameIsNobody Posted June 14, 2015 Report Posted June 14, 2015 Let's see, I generally cruise at 140 kts. So (200 - 140) / 140 = 43% increase. That's (1.43)^2 = 2.04 times the drag, and additional required power would be (cube root extra HP) = 60 or my brain hurts, I've done something wrong, it can be 216,000 hp to get 60 more knots from my plane. But let's look at Rockets, they can run 200 knots using 310 hp and 20+ gph. Think I'll stick with my 180 hp, 9 gph and no-turbo plane for now. (310 - 180) = 130 more hp; cube root of 130 = 5? Yep, 5 x 5 x 5 = 125. Something ain't right here, Bob! Ah, it's proportional! Not the raw number! Dummy . . . To go 200 knots is 60 more hp, so 60 / 180 = 33.333%. Now the cube root of 0.33333 = 0.69, or 69% more power. Rockets, however, are Mooneys, and get a partial pass on drag, so they can do it with only 60% more power but more than double the fuel. Unless I need to dig through the Performance Tables and find the actual percent power used in each situation. I'm not up for that right now. 69...heh, heh.... 2 Quote
Hank Posted June 14, 2015 Report Posted June 14, 2015 Mooney's RULE. Engineer's...drool. Mostly on fast cars and faster planes! Quote
Browncbr1 Posted June 14, 2015 Report Posted June 14, 2015 Reminds me of watching three of my engineer friends argue about the best way to setup a slip and slide for the kids. 45 minutes later, no practical difference. Power = drag 1 Quote
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