Talk:Power-to-weight ratio

message: The section about "in an aircraft it's more critical than in any other vehicle" could reworded a bit.  As far as I can tell, much of the information there applies to other vehicles as well...  "power-to-weight greatly affects top speed...  if two engines produce the same power, the lighter one will produce a better car".  The basic premise isn't incorrect, but some of the explanations don't seem to clearly differentiate aircraft from other vehicles.  --Interiot 13:00, 20 April 2006 (UTC)
replies: text: Induced drag is proportional to weight, so a heavier aircraft will consume more power for the same airspeed compared to a lighter one.  — Preceding unsigned comment added by 2.29.18.184 (talk) 09:44, 1 May 2015 (UTC)
thread_title:  Aircraft 

message: Can we go neculer with aircraft using less fuel. 
Or can we use the sun to harness the power for flight —The preceding unsigned comment was added by 68.154.210.39 (talk) 14:20, 23 February 2007 (UTC)
thread_title:  flight power (hamish)  

message: Can we go neculer with aircraft using less fuel. 
Or can we use the sun to harness the power for flight. —The preceding unsigned comment was added by 68.154.210.39 (talk) 14:21, 23 February 2007 (UTC)
thread_title:  flight power (hamish)  

message: If we're going to have a table to give people ideas of typical values, anyone else think it'd be more useful to have the power/weight ratio of the car rather than just an engine.  Automotive mags often write about power/weight ratios of cars- I haven't seen them talk about it in reference to just the engine much.  Also, anyone else think a sampling of typical cars is more informative than a bunch of exotic high-powered cars?  Friday (talk) 15:11, 29 May 2007 (UTC)
replies: text: Would someone be keen to fix the long standing anomaly of lb/hp rather than hp/lb in the lists (not just the notable low ratio one).  It seems a heap of values need inverting? 124.170.53.76 (talk) 05:37, 14 May 2010 (UTC)
thread_title:  Table 

message: Added some more cars to the list. More mainstream cars should make the comparisons more valid to most users. Also added the weights and powers for additional info. Keppelk (talk) 11:55, 31 August 2008 (UTC)
thread_title:  More cars to compare + powers/weights 

message: The Ultima GTR 720 makes 720 bhp.  —Preceding unsigned comment added by 99.59.26.101 (talk) 03:41, 19 July 2009 (UTC)
thread_title:  Ultima 

message: This article makes no mention of torque, I know the industry standard (For motor vehicles at least) is power-to-weight ratio, but torque-to-weight ratio is at least as relevant.  For example from the article:
Turbocharged V-8 diesel engine
Power to weight ratio: 0.25 hp/lb / 410 W/kg
Total Power Output: 250 hp / 186  kW
So the peak power is respectable but it isn't amazing for a V8, but being a) turbo charged, b) V8 and c) diesel, I'd hazard a guess that the torque is going to be quite impressive (I know this is probably a fictional engine and there are many other factors, but I'm grossly generalising here).  It may even have a higher peak torque than the F1 car:
BMW P84/5 2005 (Formula 1)
Power to weight ratio: 4.6 hp/lb / 7.5 kW/kg
Total Power Output: 925 hp / 690 kW
Also no mention of power curves is made, for example a V8 may have a very shallow power curve but stays above 150 kW for half of it with a peak of 200 kW, but it will have a worse power-to-weight ratio of a same weight 4 cylinder with a large turbo, sharp peak power of 250kW and average power of say 50kW.
Anyway, sorry about the rant, my point is that I don't think this article mentions the other factors enough such as power curve, torque curve and even max rpm. Hullo exclamation mark (talk) 11:43, 14 September 2009 (UTC)
thread_title:  Torque? 

message: Power-to-weight ratio is commonly given in bhp/tonne or kW/tonne... Hence power divided by weight. 
The tables in this article appear to quote weight-to-power ratios. Is this deliberate or has someone taken it upon themselves?  —Preceding unsigned comment added by 80.6.35.235 (talk) 11:42, 8 May 2010 (UTC)
replies: text: Looking at the logs, someone in the past pushed for weight-to-power ratio (as can be seen with the "power loading" mention).  The United States customary units were at that time made weight-to-power.  This appears to have been maintained.  Should it be eliminated (it does seem wrong)?  The SI units appear correctly power-to-weight.  Anyone game to make all the conversions/inversions? 124.170.53.76 (talk) 05:50, 14 May 2010 (UTC)
thread_title:  Weight-to-power - Vandalism? 

message: I've changed the table heading for 'Sports and Flight Vehicles' to read 'Sports vehicles and Aircraft', though really they need to be in separate tables. Can someone with the appropriate know-how do this?
I'm also unsure about the power specified for the Spitfire and Bf-109: these look like mid-war figures, not the figures for the prototypes as given. This needs confirmation elsewhere. AndyTheGrump (talk) 02:05, 6 November 2010 (UTC)
thread_title:  'Flight vehicles'? 

message: Consider adding electric car by General Motors – EV1. It's ratio equals 97.86 bhp/ton   — Preceding unsigned comment added by 83.26.66.28 (talk) 13:16, 26 March 2012 (UTC)
thread_title:  power to weight ratio of one notable car – GM EV1 

message: I dont know what engineer wannabe wrote this table but its COMPLETE nonsense. Its obviously calculated by this simple formula : Power = (Engine Thrust in Newtons) x (Aircraft Mach number) x 1236 / 3.6 (km/h to m/s conversion).
1-In engine specifications, the engine thrust is stated as "uninstalled thrust". As soon as it is installed into airframe, it wont be giving its uninstalled thrust. 
2-Even more importantly, intake design dictates how dynamic thrust of engines will be. A fixed inlet optimized for transonic regime wont be giving ANY thrust supersonic, no matter how powerful engine is(for example Su-25), but a optimized variable inlet can give even higher than uninstalled thrust at high supersonic speeds. To compare, a MiG-25 with 200kN total thrust 0.55 T/W, and a draggy airframe can reach M2.83 with 4 missiles, but a clean F-15C with 220kN total thrust, twice T/W and less draggy/lighter airframe cant. In short, its wrong to assume engine gives the same thrust at all speeds.
3-Engine thrust is also dependent on altitude, so its also wrong to assume sea level static thrust applies to all altitudes. (Obviously most aircraft reach their top speeds at  20000+ feet)
4-Mach number also changes with air altiude, so multiplying with 1236 is also wrong.
Most of these goes for rockets (space shuttle etc). In that case, thrust depends on altiude, airspeed, compressibility and nozzle design point. So unless anyone objects, I will be deleting all these aircraft relates bullshit from the article. Its a embarassing table for a site calles itself encyclopedia. Andraxxus (talk) 20:46, 3 June 2012 (UTC)
replies: text: I wish to second the idea of deleting or significantly altering the "Supersonic Vehicles" section, jet engines and rockets because the link between power and weight for vehicles/engines in these classes is problematic towards meaningless.  However I do see that ALL power plant forms have specific design considerations that prevent them delivering theoretical/uninstalled/laboratory performance specs.  It seems that this whole article needs a rethink.  An occasionally achieved peak power in a turbo small automobile is not directly comparable with the sustained power near peak of another multi-cylinder automobile designed to tow.  And then there is the aerodynamics of automobiles which are not even considered.  Comparing power-to-weight ratio seems only possible when comparing significantly similar vehicles under similar conditions.  In the aerospace arena, there are more variables that make significant effect on performance making comparisons virtually impossible and the power-to-weight ratio meaningless. 203.96.74.238 (talk) 05:39, 9 August 2012 (UTC)

text: I'd like to third the deletion...a quick unit conversion has the space shuttle producing 1 hp per 6 grams, which is patently absurd.  The only way to squeeze that kind of energy out of that kind of mass is explosives.  I ran some more numbers, and it seems like whoever did the math is using the empty weight of the orbiter/boosters/external tank as the weight in the calculations.  This seems to be distorting the issue significantly, since at no point does the shuttle actually produce anywhere near that kind of power to weight ratio.  In a technical sense, it is correct in that fuel weight is not usually included in the power/weight formulas, but in this particular instance it leads to utterly nonsensical numbers.  One could easily argue that the SRB engine IS the fuel, and as the "engine" weight is changing during operation, the power/weight ratio becomes meaningless. It might make sense to run the calculations for a liquid fuel rocket, but for a solid fuel rocket it's like calculating the power to weight ratio of gasoline.  I vote for deletion on the simple basis that the numbers misrepresent reality, regardless of how they were calculated.  Or, for that matter, the "technical" correctness of the calculations. 66.42.152.225 (talk) 15:40, 8 November 2013 (UTC)
replies: text:  Actually the value for rockets depends on speed, and peaks at maximum thrust at maximum speed. Rockets are indeed insanely powerful. The power of a jet-propulsion engine is MAX(thrust x speed) where thrust is a function of speed, altitude. For a rocket thrust maximises in a vacuum as there's no aerostatic backpressure on the nozzle. Towards the end of the burn the space shuttle could accelerate at over 3g at a speed of 7.8km/s. That's over 30N per kg @ 7.8km/s, 234 kW/kg or ~300 horsepower/kg, 1 horsepower for every 3.2 grams, including (remaining) propellant, tanks, astronauts everything. So twice as good as 1 horsepower for every 6 grams. Hope this helps.GliderMaven (talk) 17:05, 4 December 2013 (UTC)
replies: text: Concorde super-cruised across the Atlantic at Mach 2.0 on ~40,000lb of thrust, around the equivalent in power of a single early RB211.  — Preceding unsigned comment added by 2.29.18.184 (talk) 09:37, 1 May 2015 (UTC)

text:  This definition for "power" of a rocket is patently nonsense, as it depends on reference frame.  How much power does the rocket produce relative to the surface of the sun?  How about relative to the center of the galaxy?  Does a simple model rocket produce nearly infinite power relative to red-shifted galaxies?  All accelerating vehicles push against something; in the case of a rocket, it is pushing against the fuel in it's tanks.  By calculating the power output of the space shuttle in the fashion used above, one ignores the power already delivered to the propellants in the fuel tanks earlier in the launch cycle to accelerate them to (nearly) orbital velocity.  A more reasonable definition of the power produced by a rocket is it's thrust multiplied by it's exhaust velocity.  — Preceding unsigned comment added by 71.174.93.74 (talk) 14:50, 22 March 2016 (UTC)
thread_title:  I think "Supersonic vehicles" should be deleted 

message: Ships should be included in this article, as they are the most efficient movers of cargo, shown by the very low Power-to-weight ratio. I could not find references for the mass of an empty functional ship, but hopefully others have better luck. TGCP (talk) 14:37, 25 May 2014 (UTC)
thread_title:  Ships? 

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thread_title:  External links modified 

message: I checked the reference, there was no weight and the power was just 850 bhp. I did not find anything about 1400 bhp org weight inArrows A10 or BMW M12.
--Fisch4Fun (talk) 06:35, 17 October 2017 (UTC)
replies: text:  I inserted a reference for 1400 hp --Fisch4Fun (talk) 07:12, 17 October 2017 (UTC)
thread_title:  Formula 1 engine BMW M12 

message: I've removed the C/12 rating for the Toshiba SciB cell. The math was wrong (50A at 2.4V is 120 W, not 600W), and the cited source doesn't mention a 50A discharge at all. What it does mention is charging at 50A:
More than 90 percent of the SCiBTM cell capacity can be charged in just 5 minutes using a large charging current (max. 50A). 
Dominik Honnef (talk) 20:27, 8 September 2020 (UTC)
thread_title:  Toshiba SCiB cell 4.2Ah Li2TiO3 Lithium-ion battery Comment 

message: This article is now 78 pages long and has ~500 refs in it. How about we split the examples into another article for people who want to see the details and leave this article to explain the definition and interpretation of the concept?  Lfstevens (talk) 19:12, 13 May 2021 (UTC)
thread_title:  Split 

message: Hi, the section on electric motors appears poorly sourced and unreliable.  When the links are followed, they don't go to specific product pages and the products that are there don't seem to match the claimed results for H3X and Integral.  I was trying to verify claims and power levels and weights didn't seem to match up let alone Power/Weight ratios.  Perhaps an Editor should assess wether this is [UNRELIABLE] and wether it should remain in the article? Patbahn (talk) 17:40, 8 July 2022 (UTC)
thread_title:  Electric motors and electromotive generators : Data Problems 

message: What's the point of the lists? I do not think it passes WP:NLIST. X750. Spin a yarn? Articles I've screwed over? 21:48, 5 April 2023 (UTC)
thread_title:  Point of the lists? 

message: Remove any mention of any athletic achievement since most professional, if not all, cyclists are 'doped up to the eyeballs' and does not accurately portray their power but how well their team doctor can concoct something 'good' and undetectable to enbale them to cheat. The issue is that the cyclist mentioned was caught doping with asthma medication and collapsed from excessive use. 210.84.5.219 (talk) 14:04, 23 March 2024 (UTC)
thread_title:  Humans Power