Talk:Boeing KC-135 Stratotanker/Archive 1

Archive 1

Archive 2

Based on ?

Isn't the KC-135 built from one of the passenger jets? Like a 737 or 727? -- Zoe

• Nothing directly. It is a larger version of the Boeing 367-80 (Dash 80). The 707 is a larger version of the KC-135 as well. I believe all this is in the Development section now. -Fnlayson 17:53, 18 July 2007 (UTC)

ERRORS IN ARTICLE

The article states that the KC-135 R/T Models are only stationed at McConnell AFB, Kansas. However, references to this fact need to be presented, as I also can find references to KC-135 R/T Models used by the 92nd ARW, Fairchild AFB, Washington, which is also the largest KC-135 base in the nation.

Should this section be omitted?

I'm not the author of the above comments, but I added a "citation needed" tag for the statement in question. Itsfullofstars 00:41, 21 December 2006 (UTC)

"KC-135R/T" is the designation given to receiver KC-135s, the reference to Fairchild jets of KC-135R/T is simply saying that they have both KC-135R and KC-135T aircraft. The R/Ts are only at McConnell.Titanmiller 21:36, 16 February 2007 (UTC)

Future of KC-135

Donald Rumsfield is full of shit. Cutting the replacement program for the KC-135 means a bunch of 60 year old dinosours be dying off one by one as they reach the limits of their maintainability. This will create a severe shortage of support aircraft in a 7-10 year time frame and eventually doom america's air force to short range missions once the airborne tankers are grounded. IT WILL HAPPEN.Gohiking 15:36, 29 October 2006 (UTC)

• Yea, they obviously were working on plans for the KC-X program last fall. -Fnlayson 22:19, 16 February 2007 (UTC)

External links

The sole external link didn't work when tested on 20 Dec 2006, so I added some more. I suggest eventual removal of the link to http://aeroweb.brooklyn.cuny.edu/specs/boeing/nkc-135a.htm if the site continues to be non-responsive, but in the mean time I added a notation to say the link is non-working. Itsfullofstars 23:47, 20 December 2006 (UTC)

It appears that aeroweb is no longer viable, but back copies are available at www.archive.org (The Internet Wayback Machine), so I changed the aeroweb link to use that instead. Itsfullofstars 01:31, 22 December 2006 (UTC)

Update — Aeroweb is back online, at a new location: www.aero-web.org - Itsfullofstars 22:16, 4 February 2007 (UTC)

Italian KC-135

I've read the Seattle newspaper article that states that Italy uses 4 KC-135. However, I have printed sources that state that Italy uses military 707s for aerial refueling. (Frawley, Gerard: The International Directiory of Military Aircraft, pages 40-41. Aerospace Publications Pty Ltd, 2002. ISBN 1-875671-55-2.) I'm inclined to believe an aviation publication over a city newspaper, even one in Seattle. I'll keep checking around. - BillCJ 06:42, 4 February 2007 (UTC)

Interesting, I found this reference that also lists the aircraft as "707T/T". If they're not KC-135s, some more info really ought to be dug up on these and added in the appropriate place. I know Omega was interested in developing a tanker version of the 707, but AFAIK they only produced one prototype. Four airframes intended for the program remain in storage at Mojave. Until more info become clear, I'll modify the article's statement. Akradecki 03:13, 11 February 2007 (UTC)

The cited news article is quite old, from July 2001. The article states that by 2006 the Italian Air Force was to have 767 tankers instead... "The first of the four tankers is expected to be delivered to Italy in 2004, with the remaining three delivered in 2005 and 2006." I had deleted the first mention yesterday that Italy was using KC-135s because it was a completely unsourced assertion at the time, and it was added by a first-timer anonymous IP of 82.50.71.54. It looked more like a case of subtle vandalism to me than a legit edit, so that's why I deleted Italy from the operators. I probably should have simply added a {{fact}} tag instead. - Itsfullofstars 22:12, 4 February 2007 (UTC)

Currently Boeing is filling the order for 4 Italian KC-767s.[1] -Fnlayson 02:05, 11 February 2007 (UTC)

Here's an english translated version of the Italian AF 707 T/T data sheet. Says they got the 4 planes from Portugual. -Fnlayson 18:07, 11 February 2007 (UTC)

Mystery solved! Italy originally had 4 707-300s, 3 of which were converted to tanker configuration by Aeritalia in 1988-89. The other remained a straight freighter; it, and one of the tankers are now in storage, leaving two operational. Photos of these can be seen here. The airframes are:

MM62148, c/n 20514, built as 707-3F5C, for the Portugese AF (then operated by TAP, Nigeria A/W, Air Malta, TAP), converted by Aeritalia 1989, currently reported as in storage.

MM62149 c/n 20298, built as 707-382B for TAP, converted to -3F5C by aeritalia 1988, currently operational.

MM62150 c/n 19740, built as 707-382B for TAP, freighter only, not tanker, sold to Boeing then to Omega, currently in storage.

MM62151 c/n 20515, built as 707-3F5C, for the Portugese AF (then operated by TAP, Nigeria A/W, Air Malta, TAP), converted by Aeritalia 1989, currently operational.

I have also found that the Israeli AF also operated converted 707s, calling them "KC-707s", at least in one ref. I suppose that some of this should probably be summarized over in the 707 article sometime. I have amended the note in the KC-135 article to reflect this, feel free to reword if you think it can be said better. Akradecki 22:17, 11 February 2007 (UTC)

• Good work. Since these are not actual KC-135s (387 based), I think we should carry this to the 707. -Fnlayson 22:36, 11 February 2007 (UTC)

Service life

I stopped by to look into that citation that was needed on the "service until 2040" bit, which has already been fixed by fnlayson. But I'm now wondering if the comment is really valuable at all. That 2040 date was an estimated service retirement for the aircraft based on service lives of 36k and 39k hours for E and R models respectively. However, that's an airframe structural estimate only, and many individual aircraft would not reach these limits even by 2040 (no E models would); the estimate is for planning purposes, not a reflection of the expected service life of the aircraft. Additionally, while the average annual flight time for a 135 is about 450 hours, that's skewed down by low-annual-time aircraft assigned to some NG units. Many individual aircraft are adding hours much more quickly, and some R models will reach their 39k hour lifespan by 2030 or sooner (a unit I am familiar with is averaging ~600 hours/year on each jet, not 400). Corrosion is reducing the lifetime of the airframe structure as well, though as yet I haven't seen any official estimate of the cost of corrosion to fleet. The comment in the linked article notes that the older the planes get the more problems we discover. It also notes that "Various estimates of the lifespan of the KC-135 project the retire date out as late as 2040," which implies uncertainty and lack of agreement. I think 2040 is reported primarily for its shock value and not because the AF takes it seriously; apart from that one article on AF link (and where'd the writer get his "various estimates"?) I can't find an official source that wants to claim 2040 as an expected retirement date. All of the foregoing boils down to, do we need to have this in here at all? Isn't the article just fine with the opening sentence being "The Boeing KC-135 Stratotanker is an aerial refueling tanker aircraft, first entered service in 1957."? Thehappysmith 15:52, 26 April 2007 (UTC)

• Fair points. I moved the 2040 part and reference to the Recent developments section. -Fnlayson 17:06, 26 April 2007 (UTC)

Acronyms

What do the letters K and C in KC-135 mean? (K = Kerosin? = Jet fuel?; C = Cargo ?)--RosarioVanTulpe 17:34, 18 July 2007 (UTC)

• The C is for cargo and K means tanker. I'll find a link that explains the designation letters. See 1962 United States Tri-Service aircraft designation system for more explanation on designation system. -Fnlayson 18:01, 18 July 2007 (UTC)

USAF's oldest

Whether the B-52 or KC-135 is the oldest aircraft in service depends on several factors. The basic B-52 design is older, having first flown in 1952, while the 367-80 first flew in 1954, and the KC-135 itself flew in 1956. The KC-135As first entered service 1957, and many of these were later upgraded to KC-135E standard, and some of these are still in service (primarily ANG and AFR). The only B-52 model remaining in service is the B-52H, which first flew in 1960, and entered service in 1961. Thus, it is possible that some of the KC-135Es, and other conversions of KC-135As, are actually older than the B-52Hs in service. The best thing to do in this case is to find a recent official USAF source on which aircraft they consider the oldest, and to quote that. - BillCJ 05:51, 4 August 2007 (UTC)

Before you go too far, don't forget the mighty Tweet! I have personally seen jets from '58. I would have to get a pict to prove it though (yes, they are still flying the Tweet). — BQZip01 — ^talk 06:23, 4 August 2007 (UTC)

Oh, yes, how could I forget the Tweets? And here I just split off the A-37 Dragonfly from the T-37 Tweet page, and I forgot the poor little things! Good reason tho that we need an official source/statement of some kind. If none of the 135s in service are older that 1958 (a possibility), there could be a few Tweets older than they are! - BillCJ 06:33, 4 August 2007 (UTC)

It would be accurate to say the the B-52 is the oldest aircraft type in service, however. Or we could just delete the sentence and not deal with it. --rogerd 18:23, 4 August 2007 (UTC)

THat would probably be the best course of action for now. - BillCJ 18:55, 4 August 2007 (UTC)

Or make it "one of the oldest..". -Fnlayson 20:47, 4 August 2007 (UTC)

I agree with "one of the oldest..". --rogerd 02:17, 5 August 2007 (UTC)

Nothing to do with the discussion ! just a bye the way - the two oldest KC-135s flying are ship 0015 (55-3132) first flown 12 Jul 1957 (although now a special mission aircraft), and the oldest still as a tanker is Ship 0024 (55-3141) in-service as a KC-135E first flown (as an A model) 30 Sep 1957. Only the B-52Hs are still in service and they are from the 1960s. MilborneOne 20:40, 6 August 2007 (UTC)

• Saying the KC-135s are 'over 40 years old' is good enough to make the point. -Fnlayson 06:17, 1 November 2007 (UTC)

WikiProject Military history/Assessment/Tag & Assess 2008

Article reassessed and graded as start class. --dashiellx (talk) 13:55, 14 May 2008 (UTC)

Variants list is incomplete

I will add to it when I get time. Many variants are missing. I have flown 9 variants (KC-135A, KC-135A(RT), KC-135D (J-57 engined version), KC-135R, KC-135R(RT), KC-135T, EC-135A, EC-135G, and EC-135L) and they are not all listed. There are many more than that to add. Anybody want to help? Hoskin's book is a great reference. Fly135s (talk) 15:49, 2 July 2008 (UTC)

From what I can see from your list there is only one missing - the KC-135A(RT) all the others are mentioned either here or at Boeing EC-135. If you can find a reliable source that the KC-135A(RT) existed then it can be added. MilborneOne (talk) 16:04, 2 July 2008 (UTC)

-Been away from the site for a while and just noticed your comment on the KC-135A(RT)'s existence. Hard to believe you'd doubt my log book! Where do you think the KC-135R(RT) aircraft came from, a new build? Fly135s (talk) 18:17, 1 October 2008 (UTC)

-The EC-135Y was a KC-135 so that seems OK here. Not sure why EC-135N is listed though. -Fnlayson (talk) 16:07, 2 July 2008 (UTC)

Yes I noticed that when I re-ordered the list - I have removed it as it was never a tanker. MilborneOne (talk) 17:47, 2 July 2008 (UTC)

• Good deal, thanks. There are still things that can be done Fly135s. Add/correct info in the variants entries (and elsewhere) and add references. -Fnlayson (talk) 20:39, 2 July 2008 (UTC)

-I'm a newb so I hadn't discovered the EC-135 page yet. Thanks for the info.

Fly135s (talk) 19:49, 14 July 2008 (UTC)

Never exceed speed is wrong on one or both counts

373 knots at 26000 feet is nowhere near .90 mach. My calculations indicate that .90 mach at 26000 feet is 540 kts. This calls into question both speed numbers. 24.125.210.75 (talk) 02:01, 10 July 2008 (UTC)

Never exceed speed basically depends on altitude. It's whichever one you reach first, at higher altitudes you will reach the mach number before you reach the IAS. Fly135s (talk) 19:53, 14 July 2008 (UTC)

Elephant walk

The image at the bottom of the page - http://en.wikipedia.org/wiki/Image:KC-135_Stratotanker_Elephant_Walk.jpg - has the caption of "elephant walk" - but there is no corresponding wikipedia page, nor is it mentioned elsewhere on the article. Would anyone care to explain what it is, and alter the article appropriately? ta 82.3.241.56 (talk) 21:50, 20 May 2008 (UTC)

I would guess, from the picture and having seen pictures of elephants marching, that this refers to the nose-to-tail formation (think a train of elephants holding onto the tail in front of them with their trunk).

Pretty much. It refers to the the resemblance of a line of large planes ambling down the taxiway to a line of elephants.Raguleader (talk) 18:16, 24 July 2010 (UTC)

Expand Design Section

Though the design section references the dash-80, there is no explanation for the motivation for the development of the KC-135. The short version is that the KC-97 was too slow for the B-47 and soon to be added B-52. I've seen footage of a B-47 attempting to refuel from a KC-97 on Discovery Channel where, the B-47 stalls out just before hooking up to the probe. Supposedly the KC-97's were pushed to full throttle while the B-47 throttles back to minimum sustainable airspeed to tank up. Or is this a myth, and the USAF just wanted an all jet inventory? VeeFourAJ (talk) 20:06, 27 February 2009 (UTC)

Sure. Reasons for developing an aircraft should be covered early in the Development section. They needed a jet tanker to refuel faster aircraft (also jets). -Fnlayson (talk) 21:32, 27 February 2009 (UTC)

JKC-135A??

I was going back through some of my old photos from 25 years ago and found I have a picture of 55-3136, which is listed on various websites as a JKC-135A. Any idea what that is? Nothing I've seen answers it sufficiently except that it was some kind of test aircraft. -Rolypolyman (talk) 20:02, 14 November 2009 (UTC)

I have 55-3136 first flown 13 Aug 1957 and used in experiments to determine the effects of Aurora Borealis on radio communuications between 1957 and 58 for which it had an addition spinal antenna. It was later used in the nuclear weapon test program until it was returned to SAC in May 66. MilborneOne (talk) 21:15, 14 November 2009 (UTC)

Let me google that for you...

However, to answer your question:

King Hawes writes:

Tail number 59-1491 started out as a KC-135A and was delivered to Wright-Patterson AFB on Oct. 1, 1960 for conversion to a JKC-135A named "Nancy Rae".

After modifications, Nancy Rae deployed to Shemya on New Years Eve 1961 to record Soviet ICBM launches into the Kamchatka peninsula.

On March 1, 1963 Nancy Rae was transferred from AFSC to SAC and was converted by General Dynamics to an RC-135S (First of its kind) and renamed "Wanda Belle". The name "Wanda Belle" was changed to "Rivet Ball" in early 1967. Rivet Ball crash landed (January 13, 1969) on Shemya after returning from an operational mission.

Rivet Ball (Tail #59-1491) never flew again. Her remains ended up in the "Million Dollar Dump".

It would not surprise me to find out that the airframe you listed was one of those converted to an RC-135 variant. — BQZip01 — ^talk 21:21, 14 November 2009 (UTC)

Sorry to dissapoint but after test use it went into service as a tanker with the 917th ARS/96th Wing until it went to Davis-Monthan for storage in April 1993. MilborneOne (talk) 21:26, 14 November 2009 (UTC)

Interesting... the reason I asked is I have a picture of 55-3136, when it was a transient bird at Clark Air Base sometime around late 1981 and was parked on the MAC ramp. Apparently it was doing regular old tanker duty and was on a deployment, at least from what I can tell. -Rolypolyman (talk) 01:50, 13 January 2010 (UTC)

I could have been more clear; my comments were about the JKC-135A, not the mentioned tail number. — BQZip01 — ^talk 00:08, 14 January 2010 (UTC)

Payload/Maximum Fuel Load

According to the General Characteristics, the Payload is 83,000 lb (37,600 kg); at the same time, the article says that the "Maximum Fuel Load" is 31,275 US gal (118 kL). How can this be? 118.000 l Jet fuel should weigh more than 37.600kg? —Preceding unsigned comment added by 88.2.27.82 (talk) 19:14, 28 October 2010 (UTC)

Also, for the KC-46A, the fuel capacity is given in lbs and kg, while for the KC-135 it is given in gals and cubic meters. These need to be made consistent. Either volume or weight or both, but not one for one plane the other for another. peter (talk) 18:24, 20 August 2012 (UTC)

WP:sofixit? Nothing is stopping you from making these alterations. Do you need assistance as to how to do so? Buffs (talk) 01:30, 21 August 2012 (UTC)

Operator image

Please excuse me if this is the wrong place. The picture of the view from the boom operators view seems to be from a KC-10 tanker where the boom operator sits upright. On KC-135's the boom operator lays on his stomach. —Preceding unsigned comment added by 68.17.180.10 (talk) 00:45, 1 March 2011 (UTC)

I believe it is the camera angle that makes it appear as those the boom operator here is seated. I looked at some similar images on af.mil/photos and found a similar image that make it clear the operator is in a prone position. -Fnlayson (talk) 05:03, 1 March 2011 (UTC)

It's the camera angle. Note the chin rest, and the distinctive KC-135 boom. — Preceding unsigned comment added by 71.70.175.179 (talk) 01:33, 10 January 2012 (UTC)

Sale to Israel?

http://www.reuters.com/article/2013/04/21/us-israel-usa-hagel-idUSBRE93K03K20130421

Even Reuters is talking KC-135 rather than KC-130Js. Are we really going to sell aircraft that are almost as old as Israel? Hcobb (talk) 14:41, 22 April 2013 (UTC)

I am not sure who we are, as Israel has some really old 707s converted to tankers a few fairly recently refurbished and re-engined KC-135s would be a good deal. But like all these things we will just wait and see what if any agreement is made. MilborneOne (talk) 18:17, 22 April 2013 (UTC)

1987 Crash at Fairchild

According to the Fairchild Air Force Base page, there was a crash there in 1987:

"On 13 March 1987, a KC-135A crashed into a field adjacent to the 92nd Bomb Wing headquarters and the taxiway during a practice flight for an In-Flight Refueling Demonstration planned for later in that month. Seven were killed in the crash, six aboard the aircraft and one on the ground."

Can someone source this information? — Preceding unsigned comment added by 75.92.156.18 (talk) 20:07, 3 May 2013 (UTC)

PDF rendering Error

When I try to download this page as a PDF it keeps saying "WARNING: Article could not be rendered - ouputting plain text. Potential causes of the problem are: (a) a bug in the pdf-writer software (b) problematic Mediawiki markup (c) table is too wide" How can this problem be fixed? American Writer (talk) 00:27, 1 February 2014 (UTC)

когда я пытаюсь загрузить эту страницу как PDF-он продолжает говорить, что "предупреждение: статья не может быть вынесено - ouputting обычный текст. Возможные причины проблемы: а) ошибка в pdf-writer software (б) проблемные разметки Mediawiki (c) Таблица слишком широкая" как можно эту проблему исправить? американский писатель (обсуждение) 00:27, 1 февраля 2014 (UTC)

Similarity to 707

The 707 and KC-135 share an awful lot, remarkably similar by a reasonable standard, since they share the -80 as a "parent." Consider that they have virtually identical wingspans, heights, and lengths, were originally equipped with the same engines, and share muscle-powered servo tab flight controls (an uncommon configuration in aircraft of this size). They have virtually identical profiles (save the 135's boom), so similar that a layman can immediately pick them out as twins. The size difference is very small, really noticeable only in fuselage diameter (since the 707 carried people and baggage, who need more space than fuel.) The differences are a matter of tweaks here and there, and the family resemblance is overwhelming. What differences would you point to? 89.211.58.138 (talk) 22:20, 23 August 2010 (UTC)

The size difference is so tiny as to be insignificant. They're closer in size to each other than to the prototype 367-80. We're talking about an increase of about 4 inches from -135 to 707. Both are more than a foot bigger than the -80. Using the word "larger" really puts the wrong image in your head. They were contemporaries, and virtual twins. Calling out the differences should be left to the body of the article; the intro gives it undue prominence. 89.211.58.138 (talk) 22:35, 23 August 2010 (UTC)

It depends on if you think a 10 ft increase in length would makes the 707 larger. MilborneOne (talk) 19:45, 24 August 2010 (UTC)

The FAA considers them quite similar, at least operationally.The Federal Aviation Regulations (FAR's) Part 61.73 — Military pilots or former military pilots: Special rules. will grant a KC-135A or Q aircraft commander a Boeing 707/720 type rating. Don't know what the reengined R model equates to. Don't know if ANY 707's are still in operation anywhere in the world, so the question is largely moot now. But that's how I got the type rating on my pilot's certificate.Dwalexmd (talk) 18:25, 23 October 2014 (UTC)

Numbers don't add up

"is 96% quieter than the KC-135A (sideline noise levels at takeoff were reduced from 126 to 99 decibels)". 96% reduction of noise from 126 decibels is 5.4dB. I doubt there is even a machine to measure this tiny level of noise. 126 to 99dB reduction is just over 20%. Could someone check and correct? Or explain why I'm wrong? Le Grand Bleu (talk) 14:11, 12 July 2014 (UTC)

The Decibel scale is logarithmic, where

• $dB=10\cdot \log _{10}x$
• $x$ is the power of the sound
• ${\sqrt {x}}$ is the amplitude of the sound

In this case,

     $126dB=10\cdot \log _{10}(3.98\times {10^{12}})$

 and

     $99dB=10\cdot \log _{10}(7.94\times {10^{9}})$

 so the ratio of amplitudes is

     ${\sqrt {\frac {7.94\times {10^{9}}}{3.98\times {10^{12}}}}}=0.045$

Thus the noise (i.e. sound amplitude) is reduced by $1-0.045=95.5\%$ in going from 126dB to 99dB. Mliu92 (talk) 19:17, 21 October 2014 (UTC)

There must be something wrong here. Why is 126dB a 1? And why 0.045 is a percentage if it's the result of a square root? Since when the result of a square root is percentage? And why all of a sudden, to find a fraction one number is of another, you devide one number by the other and then take a square root out of that? Le Grand Bleu (talk) 21:13, 21 October 2014 (UTC)

Sorry, I didn't explain very well. Based on the definition of the decibel scale, $3.98\times {10^{12}}$ is the power of the noise at 126dB, and similarly, $7.94\times {10^{9}}$ is the power of the noise at 99dB. The actual volume of the noise is based on the amplitude, though, so that's why you take the square root. ${\sqrt {3.98\times {10^{12}}}}=2.00\times {10^{6}}$ is the amplitude of the 126dB noise, and ${\sqrt {7.94\times {10^{9}}}}=89.1\times {10^{3}}$ is the amplitude of the 99dB noise.

If you then subtract 95.5% of $2.00\times {10^{6}}$ (the amplitude of the 126dB noise) from $2.00\times {10^{6}}$, i.e., (1-0.955)*(126dB noise amplitude), you end up with $89.1\times {10^{3}}$ (the amplitude of the 99dB noise)=0.045*(126dB noise amplitude).

What I had written above was determining how large the amplitude of a 99dB noise is compared to the amplitude of a 126dB noise. Since both the numerator and denominator of the fraction are being taken to the square root, I divided before taking the root. ${\sqrt {\frac {7.94\times {10^{9}}}{3.98\times {10^{12}}}}}={\frac {\sqrt {7.94\times {10^{9}}}}{\sqrt {3.98\times {10^{12}}}}}={\frac {89.1\times {10^{3}}}{2.00\times {10^{6}}}}=0.045$. This means $89.1\times {10^{3}}$ is only 4.5% of $2.00\times {10^{6}}$. Hence the amplitude of a 99dB noise is only 4.5% of the amplitude of a 126dB noise, or to flip the fraction around, 99dB represents a 95.5% (=100% - 4.5%) reduction in amplitude compared to 126dB. 126dB is the 1 (or 100%) because that's the quantity you're comparing the 99dB noise against. Mliu92 (talk) 22:30, 21 October 2014 (UTC)

I'll need to investigate this further or ask someone. It just doesn't make sense. Physical laws always do! 126 decibels is very loud, so is 99 db. It CANNOT be that slight reduction is 95%. However you put it, 95% is almost the whole thing. Your explanation doesn't explain this. If it's true, then there must be another explanation or a mistake in what you're saying. Should probably ask at the aviation portal. This CANNOT be true. It just doesn't make sense. Le Grand Bleu (talk) 11:20, 29 October 2014 (UTC)

I agree the decibel scale can be confusing. The math shows 99dB does represent a 96% reduction in sound amplitude compared to 126dB, but decibels are difficult to understand intuitively. The Sound pressure article gives a few examples of sounds and their decibel levels; in the first table, there are entries for a jet engine at 1m (150dB) and a jet engine at 100m (110-140dB). Let's take the lower end of the scale and say the jet engine at 100m is 110dB.

Intuitively, we know the sound will fall off the farther away we are from the engine. So it's reasonable to think that at 100m away, the sound of the engine is much quieter. Back to decibels, then: how much quieter is 110dB compared to 150dB? It is a 40dB reduction in noise, or ${\frac {40}{150}}=26.7\%$ less than 150dB using the decibels alone. But you know that at a distance of 100m, the jet engine isn't just 27% quieter than it would be if you were 1m away from it. At 100m away from a jet engine, you would probably be able to carry on a conversation, albeit in a loud voice. At 1m away, if you're not wearing headsets and microphones, you'd be using sign language if not actually crawling away in pain.

Back to the math of decibels, then. $NdB=10\cdot \log _{10}x$, as before. We can rewrite this to solve for power as $x={10}^{({\frac {N}{10}})}$. The power of a 150dB noise is:

    ${10}^{({\frac {150dB}{10}})}=1.00\times {10}^{15}$

Similarly, the power of the 110dB noise is:

    ${10}^{({\frac {110dB}{10}})}=1.00\times {10}^{11}$

Compare the amplitudes of the two noises (by taking the square root), and the 110dB noise is just 1% of the 150dB noise:

    ${\sqrt {\frac {1.00\times {10}^{11}}{1.00\times {10}^{15}}}}={\sqrt {1.00\times {10}^{-4}}}=0.01$

In other words, the 110dB noise actually represents a reduction of 99% (not 27%) in sound pressure compared to the 150dB noise. I agree, 110dB and 150dB are both still quite loud, but 110dB is markedly quieter than 150dB. Intuitively, decibels are akin to the exponent in scientific notation.

Let's say I created a new temperature scale and called it "KelvinExponent" by defining $y^{\circ }KE=\log _{10}zK$, where $y$ is "degrees KelvinExponent" and $z$ is the temperature in Kelvin, so 2°KE=100 K (i.e., $1\times {10}^{2}K$) and 1°KE=10 K {$1\times {10}^{1}K$}. This would, by the way, be a terrible temperature scale. You recognize that the reduction in temperature is 90 K when going from 2°KE to 1°KE. Instead of saying that the temperature is reduced by 50% (1°KE is only half of 2°KE) because that's how you compute it with the KelvinExponent scale, it's more accurate to say the temperature is reduced by 90% (10 K versus 100 K). Decibels work in much the same way, it's a logarithmic scale because of the sheer range of sound pressures possible (and detectable to the human ear). Mliu92 (talk) 16:45, 29 October 2014 (UTC)

Okay, let's test your theory. If decrease from 126 to 99 dB is 96%, how much would be a reduction from 126 to 40dB? Can you use your formula for this calculation? Le Grand Bleu (talk) 14:23, 5 December 2014 (UTC)

Sorry for the late reply. The decibel formula is:

   $dB=10\cdot \log _{10}x$

So

   $126dB=10\cdot \log _{10}(3.98\times {10^{12}})$

and

   $40dB=10\cdot \log _{10}(1.00\times {10^{4}})$

Hence

   ${\sqrt {\frac {1.00\times {10^{4}}}{3.98\times {10^{12}}}}}=0.000050$, so the 40dB sound is only 0.005% the amplitude of the 126dB sound, it represents a 99.995% reduction in amplitude compared to the 126dB sound. Going back to the examples given for various real-world sounds compared to their decibel levels, 40dB describes a normal conversation at 1m, while 120dB describes a vuvuzela at 1m. — Preceding unsigned comment added by Mliu92 (talk • contribs) 06:31, 5 March 2015 (UTC)

External links modified

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• Added archive https://web.archive.org/20080427182121/http://www.aeroflight.co.uk:80/waf/italy/italaf4.htm to http://www.aeroflight.co.uk/waf/italy/italaf4.htm

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Cheers. —^{cyberbot II}_{Talk to my owner:Online} 13:44, 26 August 2015 (UTC)