Ah brute force

Post #207,626 by tuberculosis 5/16/05 1:46:45 PM Reply	Ah brute force that'll get her movin. Thing I find cool about the Cirrus is the parachute recovery system. Apparently it has been used a couple times now and it works. Now if the insurance companies would give them a big discount for the nifty safety feature maybe more of us could afford them. "Whenever you find you are on the side of the majority, it is time to pause and reflect" --Mark Twain "The significant problems we face cannot be solved at the same level of thinking we were at when we created them." --Albert Einstein "This is still a dangerous world. It's a world of madmen and uncertainty and potential mental losses." --George W. Bush
Post #207,980 by mmoffitt 5/18/05 1:12:26 PM Reply	What I find interesting is ... the general willingness of pilots to sacrifice useful load for speed (and sometimes not for too much speed). Take, fer instance, the venerable 172. Mine (a 1960) has a useful load of 890 pounds. With full fuel I still have 650 pounds left. But later models (with bigger engines and no great increase in speed) have far less than that. A new one has a book useful load of 830 pounds and with full fuel (on 10 gal/hour burn) is 512 pounds. That's 138 pounds LESS. And the speed difference between the two? Hardly worth mentioning. I know, I know, it's the radios, seats, etc., and 5-8 knots can be huge in cruise speed. But isn't "getting there" all the fun anyway? I find it ironic that you can pay so much to haul so little. bcnu, Mikem Eine Leute. Eine Welt. Ein F\ufffdhrer. God Bless America.
Post #208,053 by Ashton 5/19/05 2:28:20 AM Reply	"pay so much to haul so little" Motorcycles. Have to be the most efficient means (with an IC engine, etc.) on land. (Not how muvh Bigger were all those roads and mews and alleys in UK, back when alot of their population rode solo, then added a sidecar when the kiddies came. Also their Petrol Bills. Pity we have yet to see the Real, Useable, Air-Motorcycle (aside from the factor of too many people incompetent to drive such a thing..) And yes, I've seen several snazzy proposals through the years; was once interested in a Benson Gyrocopter (til I read the crash stats and noted the vulnerability of Those rotors.) But in Principle - Air-cycle could Do It. In nice weather. :-)
Post #208,095 by tuberculosis 5/19/05 2:04:13 PM Reply	Bigger engines don't make planes go faster they make them climb faster. That's it. Our club in Pontiac MI had 2 172's. One of them they sent out to get a nice shiny/slippery emron paint job and put in a 180hp engine upgrade. Result? (Apart from the lovely cosmetics of new paint) Much improved climb performance, increased fuel consumption of about 1.5 gph and no net increase in speed. Similar results were had for an engine upgrade for a SkyVan at an Arizona dropzone. Vastly improved climb rate (which is what you want for a jump plane). But according to pilots, no real improvement in cruise. I would also add that a stock 172 is pretty much a non-starter someplace like Denver. You need the extra power in the mountains - again for climbing. If you want to go fast, its all about the airframe and drag reduction. You could add a rocket to a 172 and never get that airframe to VNE in straight and level flight. "Whenever you find you are on the side of the majority, it is time to pause and reflect" --Mark Twain "The significant problems we face cannot be solved at the same level of thinking we were at when we created them." --Albert Einstein "This is still a dangerous world. It's a world of madmen and uncertainty and potential mental losses." --George W. Bush
Post #208,098 by Another Scott 5/19/05 4:32:14 PM Reply	s /emron/Imron :-)
Post #208,107 by drewk 5/19/05 5:14:21 PM Reply	Is the problem propeller pitch? With the same RPM and the same prop, it doesn't matter how many HP you've got. To increase speed you need either higher RPM or steeper pitch. Do engine upgrades typically include new props? I'm assuming that the smaller planes we've been looking at here have fixed-pitch props. Am I wrong about that? === Purveyor of Doc Hope's [link\|http://DocHope.com\|fresh-baked dog biscuits and pet treats]. [link\|http://DocHope.com\|http://DocHope.com]
Post #208,119 by tuberculosis 5/20/05 9:50:56 AM 5/20/05 9:53:54 AM Reply	Yep - new props with more "bite" Still can't beat the drag on the frame though. I recall that the upgraded 172 required that you apply power more gradually while building up speed on the runway. Otherwise the prop would "stall" and your takeoff roll would be much prolonged. I should mention that they stuck with fixed pitch prop for "simplicity". More advanced planes have props that let you vary the pitch and I think you don't upgrade these, you just end up tuning the pitch differently. Pitch is selected based on engine manifold pressure at some rpm. "Whenever you find you are on the side of the majority, it is time to pause and reflect" --Mark Twain "The significant problems we face cannot be solved at the same level of thinking we were at when we created them." --Albert Einstein "This is still a dangerous world. It's a world of madmen and uncertainty and potential mental losses." --George W. Bush Edited by tuberculosis May 20, 2005, 09:53:54 AM EDT Expand All History
Post #208,122 by drewk 5/20/05 9:56:00 AM Reply	So the problem is ... It sounds like the problem is that a prop of a given diameter can only generate a certain amount of thrust no matter what pitch and RPM you use. Once you reach that point, your only options are less drag or a larger prop. And the larger prop presents ... interesting issues for take-off and landing. === Purveyor of Doc Hope's [link\|http://DocHope.com\|fresh-baked dog biscuits and pet treats]. [link\|http://DocHope.com\|http://DocHope.com]
Post #208,134 by mmoffitt 5/20/05 3:28:10 PM Reply	Hold it. Are you saying that there is no relation between horsepower and cruise? I'm not taking issue with what you've said, but I've never heard anyone say there is no relation between horsepower and speed until now. IOW, the fact that a 1960 fixed pitch, 145hp 0-300 172 trues out at 109 knots and a 2004 fixed pitch, 180hp Lycoming 172 trues out at (about) 120 knots is at least partially due to the extra 35 horses. Disagree? If the extra horses ONLY allow you to climb better, why is the service ceiling of the 1960 significantly HIGHER (15,100 compared to 13,500) than the 2004? It take that much more horsepower to raise the extra 250 gross weight? bcnu, Mikem Eine Leute. Eine Welt. Ein F\ufffdhrer. God Bless America.
Post #208,144 by tuberculosis 5/20/05 5:31:32 PM Reply	Re: Hold it. "Are you saying that there is no relation between horsepower and cruise?" I'm saying it is weak. ((180-145)/145) * 100% = 24% increase in power ((120-109)/109) * 100% = 10% increase in speed Not so obvious of a win. To really make power increases count you have to clean up the airframe. For any given airframe, resistance follows a square law. You must square your power to double your speed. Doubling your power will be fairly disappointing experience. "Whenever you find you are on the side of the majority, it is time to pause and reflect" --Mark Twain "The significant problems we face cannot be solved at the same level of thinking we were at when we created them." --Albert Einstein "This is still a dangerous world. It's a world of madmen and uncertainty and potential mental losses." --George W. Bush
Post #208,149 by mmoffitt 5/20/05 5:38:29 PM Reply	Agreed. bcnu, Mikem Eine Leute. Eine Welt. Ein F\ufffdhrer. God Bless America.
Post #208,274 by CRConrad 5/23/05 4:56:57 PM Reply	Uh, square law = Must quadruple power to double speed, no?
Post #208,279 by drewk 5/23/05 5:08:31 PM Reply	Nah, make him try for 21025 hp === Purveyor of Doc Hope's [link\|http://DocHope.com\|fresh-baked dog biscuits and pet treats]. [link\|http://DocHope.com\|http://DocHope.com]
Post #208,291 by CRConrad 5/23/05 5:29:29 PM Reply	Thing is, if you square it in kW, it makes only 15474.4 hp. 145 * 0.736 = 106.72 106.72 * 106,72 = 11389.1584 11389.1584 / 0.736 = 15474.4 I don't think REAL laws of physics let themselves be influenced by what unit of measurement one applies them in, so I REALLY don't think one's supposed to "square the power". (Another way to see that that's meaningless is, consider what it's supposed to MEAN. How the heck would you "square" a "power"?!? You know, a distance squared is an area, and so on -- but what IS a "power, squared"?) [link\|mailto:MyUserId@MyISP.CountryCode\|Christian R. Conrad] (I live in Finland, and my e-mail in-box is at the Saunalahti company.) Your lies are of Microsoftian Scale and boring to boot. Your 'depression' may be the closest you ever come to recognizing truth: you have no 'inferiority complex', you are inferior - and something inside you recognizes this. - [link\|http://z.iwethey.org/forums/render/content/show?contentid=71575\|Ashton Brown]
Post #208,296 by drewk 5/23/05 5:41:31 PM Reply	An 8-legged animal lifting a bucket that grows as it rises? </reference class="obscure?"> === Purveyor of Doc Hope's [link\|http://DocHope.com\|fresh-baked dog biscuits and pet treats]. [link\|http://DocHope.com\|http://DocHope.com]
Post #208,351 by CRConrad 5/24/05 3:28:15 AM Reply	"Itsy Bitsy Sleipner..." ? Yep, obscure as Hell. WTFDYM? [link\|mailto:MyUserId@MyISP.CountryCode\|Christian R. Conrad] (I live in Finland, and my e-mail in-box is at the Saunalahti company.) Your lies are of Microsoftian Scale and boring to boot. Your 'depression' may be the closest you ever come to recognizing truth: you have no 'inferiority complex', you are inferior - and something inside you recognizes this. - [link\|http://z.iwethey.org/forums/render/content/show?contentid=71575\|Ashton Brown]
Post #208,358 by Another Scott 5/24/05 8:27:24 AM Reply	I think he meant a 16-legged horse lifting a weight...
Post #208,380 by drewk 5/24/05 12:58:30 PM Reply	Defn: horsepower The term horsepower originated with James Watt, who determined by experiment that a horse could do 33,000 foot-pounds of work a minute in drawing coal from a coal pit. I remembered it as the horse lifting a bucket via a pulley system. And to get that squared you would need horse * horse[1] and the work would have to increase as it's pulled. [1] When multiplying horses, do you end up with 16 legs, or two horses in an X configuration through the spine? === Purveyor of Doc Hope's [link\|http://DocHope.com\|fresh-baked dog biscuits and pet treats]. [link\|http://DocHope.com\|http://DocHope.com]
Post #208,489 by Ashton 5/25/05 3:06:30 AM Reply	..it's hard to get this stuff across to Fundies_____er, :-\ufffd
Post #208,292 by mmoffitt 5/23/05 5:29:32 PM Reply	Turbine ---aaaaaaaaahhhhhhhhhhhhh--- Turbine. bcnu, Mikem Eine Leute. Eine Welt. Ein F\ufffdhrer. God Bless America.
Post #208,295 by Another Scott 5/23/05 5:39:32 PM Reply	Power required goes as cube of speed. [link\|http://www.getfaster.com/Techtips/Physics6.html\|Linky] of required horsepower to overcome wind resistance using a hypothetical Corvette as an example: [image\|http://www.getfaster.com/BIS/Techtipdata/_8387_tabular103.gif\|0\|Power needed to overcome wind resistance for a car\|63\|409] The force against the air varies as the square of the speed, but the horsepower required gives another factor v, giving the cube relationship. HTH. Cheers, Scott.
Post #208,354 by CRConrad 5/24/05 4:51:56 AM Reply	"cube of speed" - again, what units? km/h cubed != mph cubed Be it cubes or squares or whateverthefuck, my point was: What we're interested in here is the cube [or square, etc] of the change in speed (or, IOW, the cube of the ratio of speeds) -- but NOT the "cube of the speed". My original post was an attempt to correct [link\|http://z.iwethey.org/forums/render/content/show?contentid=208144\|Todd's "You must square your power to double your speed"]; that's why I talked about squares there. But what I am really trying to say is, it just makes no sense to talk about "squaring" -- or "cubing" -- one's speed or power or something like that; the very concepts of "speed squared", or "power cubed", etc, do not exist. One way to realize this is, try to explain them in plain words.() And words are what I'm talking about: From da Todd's post, it was plain he was misusing them. De Scott, I'm not so sure about; if by "goes as" you're trying to imply that the rates of change* on both sides of the equation are related, then you're right... But since you're not explicitly saying, "...goes as cube of speed goes" or "...varies as the square of the speed varies", I'm not so sure. Oh well, never mind... In general terms, though, the whole category of laws -- "square law" (if that is the correct expression?) -- Todd mentioned means, not "you must square X to double Y", but "you must quadruple X to double Y"; likewise, "a cube law" would mean, not "you must cube X to double Y", but "you must multiply X by eight to double Y. (At least, if what you showed is called "a cube law", then this is how "cube laws" work -- because what you showed works exactly the way I've been saying.) This is because quadrupling is "the square of doubling", so to speak, and multipling by eight is "the cube of doubling". It is the rate of change that is squared, or cubed or whatever; not the basic measurement itself. Still clear as mud, or what? (): As an example, I can explain "speed": It measures how far you can go in a given amount of time, and therefore it is measured as "distance per time" -- km/h, mph, m/s, etc. Acceleration: How much faster you're getting over time, hence (distance per time) per time -- (m/s)/s, or whatever units you use. Area: How big a surface is, which grows linearly with both the length and the width; hence, distance times distance or square foot, square meter, etc. But "speed squared"?!? WTF is that; it'd be measured in distance-squared per time-squared... So is it some kind of area-acceleration, then, or, uh...? [link\|mailto:MyUserId@MyISP.CountryCode\|Christian R. Conrad]* (I live in Finland, and my e-mail in-box is at the Saunalahti company.) Your lies are of Microsoftian Scale and boring to boot. Your 'depression' may be the closest you ever come to recognizing truth: you have no 'inferiority complex', you are inferior - and something inside you recognizes this. - [link\|http://z.iwethey.org/forums/render/content/show?contentid=71575\|Ashton Brown]
Post #208,357 by Another Scott 5/24/05 8:26:00 AM Reply	The linky explains all that. The constant factors in the equation take care of the units. Remember R, the Ideal Gas Constant? It's used in: PV = nRT It has about eleventy-seven values depending on the system of units you're using - SI (kg, m, s, K) or cgs (g, m, s, K) or US ("lbs", ft, s, F) or ... Similarly, the power needed to overcome the friction due to air is proportional to the cube of the speed. If you measure power in HP and speed in mph, then constant factors in the equation will be different than if you measure power in KW and speed in m/s. But the functional relationship is the same no matter what units you choose - power required varies as the cube of the speed. If it's not clear, then think about finance. The amount of "money" you need to buy a bottle of whiskey at a particular duty-free store doesn't depen on what currency you use. It might be $100 or 10,728.57 Yen. It's the same amount of "money" - just the units change. (Assuming no transaction costs, of course.) Finally, you write: What we're interested in here is the cube [or square, etc] of the change in speed (or, IOW, the cube of the ratio of speeds) -- but NOT the "cube of the speed". No. Starting at 0 and going to 50 mph takes a lot less power than starting from 500 and going to 550 mph. The change is the same, but the power required is very different. The incremental change is much smaller in the latter case too (55/50 vs "50/0"), but the power required is much larger. It really just falls out of the [link\|http://www.getfaster.com/Techtips/Physics6.html\|equation]: [image\|http://www.getfaster.com/BIS/Techtipdata/_8387_tex2html_wrap153.gif\|0\|Equation for HP to overcome air resistance\|37\|394] If v is the vehicle speed in miles per hour, then P is in horsepower. The constants in the equation will be different if the units of speed and power are different. Units can be very tricky. E=mc^2 and similar relationships in physics implies all sorts of interconnections between units that can be hard to get ones head around... HTH a bit. Cheers, Scott.
Post #208,449 by tuberculosis 5/24/05 7:09:40 PM Reply	Oh fer cryin out loud (new thread) Created as new thread #208448 titled [link\|/forums/render/content/show?contentid=208448\|Oh fer cryin out loud] "Whenever you find you are on the side of the majority, it is time to pause and reflect" --Mark Twain "The significant problems we face cannot be solved at the same level of thinking we were at when we created them." --Albert Einstein "This is still a dangerous world. It's a world of madmen and uncertainty and potential mental losses." --George W. Bush
Post #208,649 by Ashton 5/26/05 5:02:00 AM 5/26/05 5:49:12 AM Reply	Yup.. bloody pounds! and feet! + Another formula: and lbs-wt and lbs-force, ounces, drams, quarts! (But I thoroughly enjoyed \ufffd/s/d, that octagonal 3-p? and the merchants' Machiavellian means for extracting an extra Shilling: the Guinea! Also.. doing the mileage calc with 5/4 for the 5 qt. Imperial gallon, km/mi vs litres at the pump -- BSF, Whitworth wrenches vs metric or US: all kept little grey cells doing stuff-in-head. Prevents mind-rot.) I've often wondered if rampant Murican iggerance of the metric system (except in actual science courses; never mind computer-'science') accounts significantly for the current official Dumbth/sec\ufffd acceleration, plus most of the Innumeracy -?- for which we are also deFamed. Why, even those non-UAV heathen countries -- at least among their whatever %educated -- do not saddle their tykes with Ridiculous archaic BS-units as lead to furlongs/fortnight and the other albatrosses hung about the scrawny necks of our now regularly drugged, I-podded tykes. BTW, I recall a formula for estimating HP needed at any given speed (corrected for aforementioned Puritan units chaos). 'Twas the mechanical-drawing instructor -remember when ya drew stuff?- who tossed this one out to us freshmen (about the time he demonstrated How the el-cheapo Brownie movie camera outperformed its 'precision-Swiss' competition): HP = 1.21 (MV/T) HP = er HP M = mass in kilopounds [fully Muricanized for assimilation] V = Velocity of interest, in MPH (speed is scalar; velocity is vector - call it a straight line forward ;-) T = time [d'oh] for following procedure: A) Accelerate to (V+5) mph B) Clutch in (or auto in neutral) and start timer C) Stop timer when speedo reads (V-5) mph No STP or rho corrections but reveals surprising things, like that little Corvette chart. Especially: how little HP is needed at modest speeds. Works on motorcycles, I found and as one would suppose. (There - you can change! your A frontal area; sit-up, crouch - note the Different readings - you too can Believe in physics.) (I have to try this on my new sled in 30 mph increments between 40 and 130, on a next in-car-ceration on a boring Interstate; hmmm.. set cruise to V+5 and kill it, as switch to N and start timer) Bon appetit Edit: grey-cells are unsure of the "1.21" constant.. think it more likely than original '1.51' from visceral memory. Order of magnitude is right, and whatever the error in an HP point, the \ufffd law relationship should be ~ demonstrated. (Most are surprised at how little HP is needed at 30-40 mph.) Edited by Ashton May 26, 2005, 05:49:12 AM EDT Expand All History
Post #208,656 by Another Scott 5/26/05 7:45:23 AM Reply	Neat. There's probably a [link\|http://www.journals.uchicago.edu/Isis/journal/demo/v000n000/000000/000000.text.html\|nomograph ][1] of that out there somewhere. Those were amazingly handy at times. Cheers, Scott. [1] Found on Edward Tufte's site, [link\|http://www.edwardtufte.com/bboard/q-and-a-fetch-msg?msg_id=0000Bc&topic_id=1\|here].
Post #208,766 by Ashton 5/26/05 9:53:39 PM Reply	Funny you should mention.. * John Scott Campbell also pushed samples of such into our tiny little nascent minds! I recall using one of his in several courses, and also making one.. for some silly purpose ot other. But then, when your Only calculator is a K&E log-log-Decitrig and log tables - this is no Big Deal. (Saw a 17-place log table once. Huge tome! Need Reo Speedwagon to cart around for surveying n'such) Today, however - nomographs could well fill-in a bit, for necessary look-ups by the vastly-innumerate majority. If 'we' were smart enough to hand them out, that is. And if they were smart enough to realize they needed one. And - - Hmmm - MPG at the gas pump? Naah.. take out the throwaway $3 4-banger. * (Aforementioned ept, vastly curious and widely read 'drawing' instructor.) JC possessed a Novachord ~ like a synthesizer; long before there was a decent techno, or even transistors. Had a prof. Ampex tape recorder - I accompanied it and him to LA Philharmonic to tape the debut of a new pianist. He also wrote an opera for local performance: Spooks in the Basement (..of the Physics Building) (!!!). Who Says -?- being.. engineerish means: ya gots to be a one-dimensional dork? (Well, the envious do, but then...) Dynamic nomograph: 2 nails in a board, with a string around: make ellipses! Sometimes I miss analyt. geom. - I mean, who ever today has the foggiest what a Latus Rectum might be?
Post #208,670 by boxley 5/26/05 10:18:29 AM Reply	every redneck with a wrench knows that 14mm=* 9/16ths All tribal myths are true, for a given value of "true" Terry Pratchett [link\|http://boxleys.blogspot.com/\|http://boxleys.blogspot.com/] Any opinions expressed by me are mine alone, posted from my home computer, on my own time as a free american and do not reflect the opinions of any person or company that I have had professional relations with in the past 48 years. meep questions, help? [link\|mailto:pappas@catholic.org\|email pappas at catholic.org]
Post #208,684 by CRConrad 5/26/05 11:08:41 AM Reply	Bah; old-Volvo fans know 14mm wrench will NOT fit 9/16 bolt!
Post #208,708 by boxley 5/26/05 2:09:09 PM Reply	horses duervers! fits just fine which is what I use all the time as the 9/16th wrenches are dissapeared by the IDunno Bike fixing fairy. thanx, bill All tribal myths are true, for a given value of "true" Terry Pratchett [link\|http://boxleys.blogspot.com/\|http://boxleys.blogspot.com/] Any opinions expressed by me are mine alone, posted from my home computer, on my own time as a free american and do not reflect the opinions of any person or company that I have had professional relations with in the past 48 years. meep questions, help? [link\|mailto:pappas@catholic.org\|email pappas at catholic.org]
Post #208,731 by CRConrad 5/26/05 4:24:53 PM Reply	Funny. Either your bolts or your wrenches are off measure. Since 9/16ths of an inch is about 14.3 mm. Or maybe your bolt heads aren't 9/16ths at all, but 14 mm. [link\|mailto:MyUserId@MyISP.CountryCode\|Christian R. Conrad] (I live in Finland, and my e-mail in-box is at the Saunalahti company.) Your lies are of Microsoftian Scale and boring to boot. Your 'depression' may be the closest you ever come to recognizing truth: you have no 'inferiority complex', you are inferior - and something inside you recognizes this. - [link\|http://z.iwethey.org/forums/render/content/show?contentid=71575\|Ashton Brown]
Post #208,769 by boxley 5/26/05 10:09:20 PM Reply	try 13.8 mm if larger than, it would fit on would it? most tools of men with children are made in china with the resultant tolerance differences. thanx, bill All tribal myths are true, for a given value of "true" Terry Pratchett [link\|http://boxleys.blogspot.com/\|http://boxleys.blogspot.com/] Any opinions expressed by me are mine alone, posted from my home computer, on my own time as a free american and do not reflect the opinions of any person or company that I have had professional relations with in the past 48 years. meep questions, help? [link\|mailto:pappas@catholic.org\|email pappas at catholic.org]
Post #208,791 by CRConrad 5/27/05 8:20:07 AM Reply	No, IF 13.8 mm were larger than 14 mm then a 14 mm wrench... ...would STILL not fit on a "13.8 mm" bolt-head. Or what the FUCK were you trying to say?!? For once, your body text was much clearer than the headline. Too bad the headline was total gibberish... Yeah, sure, it COULD be that your el-cheapo Chinese tools() have such humongously sloppy "tolerance differences" that a nominally "14 mm" wrench would fit on a 9/16" (14,2875 mm) bolt-head. Or maybe your bolts are Chinese too -- WTF do I know (or care)... Anyway, that's what I frigging SAID -- "Either your bolts or your wrenches are off measure" -- before, isn't it? So, uhmm... What the fucking fuck are you objecting to here??? () BTW, haven't you ever heard the old saying, "the poor man can't afford to buy cheap"? [link\|mailto:MyUserId@MyISP.CountryCode\|Christian R. Conrad] (I live in Finland, and my e-mail in-box is at the Saunalahti company.) Your lies are of Microsoftian Scale and boring to boot. Your 'depression' may be the closest you ever come to recognizing truth: you have no 'inferiority complex', you are inferior - and something inside you recognizes this. - [link\|http://z.iwethey.org/forums/render/content/show?contentid=71575\|Ashton Brown]
Post #208,411 by jbrabeck 5/24/05 2:24:29 PM 5/24/05 2:27:03 PM Reply	OT: Hey CRC I'm looking for you in Open Forum [link\|http://z.iwethey.org/forums/render/content/show?contentid=208265\|Translation] edit: pointed link to start of thread A good friend will come and bail you out of jail ... but, a true friend will be sitting next to you saying, "Damn...that was fun!" Edited by jbrabeck May 24, 2005, 02:27:03 PM EDT Expand All History

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