Talk:Pratt & Whitney F135

Thrust contradictions
How is it that the connected article, F-35 Joint Strike Fighter says the F135 produces 165kN thrust and this article says the F135 delivers 178kN as well as miraculously managing to bleed air to the roll posts each producing 8.7kN and drive a gearbox which also provides 80kN of thrust. Someones sums don't add up - get it right or leave it out!


 * There are a lot of people who assume things they don't even know about.


 * Actually this article states that the engine delivers a total thrust of 276kN, far greater than the 165kN stated on the F-35 page. Perhaps someone was just attempting to list the stats like in the F136 page, but failed to do so correctly. I think it's obvious that the Air Force would not want to switch from a 276kN engine to a 178kN one. According to http://www.pratt-whitney.com/prod_mil_f135.asp and http://www.rolls-royce.com/defence_aerospace/products/combat/f136/tech.jsp both the 135 and 136 have the same thrust though they are probably just rounded figures. AAK 13:37, 9 August 2006 (UTC)


 * I've edited the engine thrust stats to the ones stated here. I used google calculator to convert the pounds of force to kiloNewtons and when summing up the total thrust, I got 177 kN, which if correct, means that the F-35 article is wrong about the 165 kN. AAK 14:27, 9 August 2006 (UTC)


 * The F135 has multiple measures of thrust. One is the dry thrust at about 25k Lbs. One is wet thrust (when the afterburner is on) which exceeds 40k lbs. Additionally there is thrust while in hover, which is the sum of the lift fan's cold thrust, and the thrust coming out of the roll posts and the nozzle which is again in the realm of 40k lbs. Afterburner is not used for hovering. (duh)


 * To add a little more confusion to the chaos, I've added a specs table using Jane's performance numbers for the engine, which are slightly different than what's in the article. I tend to trust Jane's, so as I edit this article I will try and update the numbers to be consistant. - SidewinderX (talk) 12:13, 29 July 2009 (UTC)

Neutrality?
There are a couple spots here that sound a little off to me.

''"The F135 propulsion system already proved that it can meet these diverse requirements, during preliminary flight testing of the Boeing X-32 and Lockheed Martin X-35 aircraft in 2000." I think this can be reworded to say something like "The F135 first flew as the engine that powered both of the JSF competitiors, the Boeing X-32 and the Lockheed Martin X-35".''

I also think the following line should be removed; the article is about the engine, not the F-35. ''"As planned, new F-35 aircraft will replace the F-16 Fighting Falcon, AV-8B Harrier II, and F/A-18 Hornet." ''

Also, I think this paragraph (below) needs to be rewritten a bit:

"Propulsion system support and maintainability are further enhanced by the F135's maintenance-focused design. It has approximately 40 percent fewer parts, which also improves reliability. All line-replaceable components (LRCs) can be removed and replaced with a set of six common hand tools. And, the F135 has a 50 percent lower infrastructure support requirement compared to current engines. The F135 produces 40,000 lbf (180 kN) of thrust,[1] the most ever in a fighter engine.[2]"

Any thoughts? - SidewinderX (talk) 20:23, 28 July 2009 (UTC)


 * Go for it. Most of that sounds like brochure wording, as some users tend to just copy in sections from company sources. - - BilCat (talk) 01:33, 29 July 2009 (UTC)


 * Agreed, those changes are good. -Fnlayson (talk) 01:40, 29 July 2009 (UTC)

There are also issues over claims of costs, like: "In 2013 the price of the F135 increased by $4.3 billion. ". A single engine does not cost 4.3 billion thats the price on a contract for an unspecified number of engines. Someone needs to clean this article up its a mess of FUD.50.247.253.194 (talk) 20:47, 8 June 2020 (UTC)

Current Rework (Jul 09)
I've started to rework this article. My main goals are to flesh out the technical information based on what's available, do a better job of citing, and rewrite the sections that read like they're press release copy (which they are).I would also like to add more images. Feel free to point out specific areas that need help. Thanks! SidewinderX (talk) 13:46, 29 July 2009 (UTC)

Design Section
I have started a bit of work on the design section and I'm trying to be respectful of the original author's contributions, but I'm having a bit of trouble. It mostly reads (as pointed out earlier by BilCat) like brochure copy, and that's what I'm guessing it's from. That said, I'm sure there's some useful info in there, but I just don't understand some of it. For example the paragraph that starts "A feature of the F135 STOVL engine is flow multiplication...". I think that's talking about just the lift fan system, but I'm not sure. Any idea how to reword that, or should I just bulk rewrite it? SidewinderX (talk) 15:12, 10 August 2009 (UTC)

LiftFan Thrust (HCobb)
The wording you added seemed misleading to me. While the total thrust in STOVL is close to wet thrust in conventional mode, they're not comparable. 20,000lbf of that lift is coming from the lift fan, which in the vertical axis, not the horizontal. Comparing that to the afterburning thrust is misleading because that liftfan thrust isn't used to propel the aircraft forward. Maybe that paragraph in the article needs to be rewritten to clarify that that thrust is basically in the vertical direction, not the horizontal. SidewinderX (talk) 16:08, 10 August 2009 (UTC)


 * 100% of the thrust goes vertical so the lift fan is acting as a pure additive to the main engine thrust. Hcobb (talk) 16:39, 10 August 2009 (UTC)


 * Hmm, your rewording is better, but I still don't like what it's implying, and there are a few "errors" IMO. First, afterburning flight isn't always supersonic flight; rewording that to say afterburing thrust (or wet thrust) would be better I think. I also think that stating that the lift fan uses no additional fuel and generates no additional heat is unsourced at best or just wrong at worst. I'm not sure if the engine uses more fuel or not when the clutch engages for the lift fan. I'm sure it doesn't use as much as the afterburer (which is what you seem to want to say), but it's definitly possible it uses more fuel to keep the LP sections turning. Secondly, it definitly generates more heat. Not in the way that you seem to mean (afterburner exhaust heat), but turning all those parts and compressing/blowing air through the lift fan definitly generates more heat. I think you're just trying to make the point that the lift fan adds a lot of thrust to the engine for STOVL, which is true, but I don't think you're going about it the best way. Just leave the line about how much thrust that STOVL system generates compared to the wet thrust and that is fine IMO. (wow that was long, sorry) SidewinderX (talk) 20:07, 10 August 2009 (UTC)


 * I apologize for the lack of turbofan function in the File:JetEngineGraph-LiftFan.PNG, but it is kinda hard to show both mixed (turbofan) and unmixed (turbojet/turboshaft) functions in the same engine. The F135 engine and LiftSystem concepts are complex and not easily understood, and give rise to many misunderstandings and false assumptions. I have tried to show a different angle with that diagram and the File:LiftThrust-small1.PNG, but I would like a discussion on how to present the engine more clearly. The LiftSystem article does not allow F135-functions to be included, but I do not think they can be separated, as the dual power cycle of the F135 is critical for the operation of LiftSystem. TGCP (talk) 11:08, 22 May 2010 (UTC)

Development
I've made a couple of changes to rationalize the failure details since they were based on a few poorly worded sources as well as poor interpretation of the source in one instance. Hope that's ok.Pieter1963 (talk) 20:12, 1 January 2015 (UTC)

Design
This section was a bit disjointed, I think, because it is made up from contributions from many editors. I have tried to tidy it up still keeping those contributions except: removed statements which gave a personal interpretation of what is described in cited sources, removed sales brochure-type terminology, removed duplicated details.Pieter1963 (talk) 23:12, 28 January 2015 (UTC)

Unit Cost - Numbers?
Nothing on unit cost except for "continuing the unit cost decreases," "substantial cost growth," and "below the cost of the F119"? Decreases from what number? Growth from what number? What (number) below what other number? — Preceding unsigned comment added by 144.183.224.2 (talk) 21:59, 27 August 2015 (UTC)

"serious readiness problem"
https://www.defensenews.com/air/2021/02/12/an-engine-shortage-is-the-newest-problem-to-hit-the-f-35-enterprise/

Why is this not notable? Hcobb (talk) 16:31, 24 February 2021 (UTC)

About F135 being the most poweful jet engine ever fitted to a fighter jet.
I added a referenced fact that the F135 is the most powerful fighter jet engine ever, yet my addition was removed. I don't understand why. Thank you for your thoughts!Filip.vidinovski (talk) 10:53, 30 October 2021 (UTC)


 * It was explained in the edit summary. Not mentioned is the fact that the text was inserted in to the lead of the article without it appearing in the body text (the lead is a summary of the whole article per WP:LEAD).
 * Claims (supported or not) that involve adjectives such as 'most powerful', 'longest', 'smallest etc', are avoided as they encourage puffery and edit wars. Another problem is that claims go out of date, another subject becomes the 'best/most powerful etc' but the incorrect text remains unless attentive editors are watching the article carefully. Nimbus (Cumulus nimbus floats by)  11:50, 30 October 2021 (UTC)
 * I understand the problem with the claims such as "the best", but this is an verifiable fact about an objective quantity. Also, there are other articles that involve similar adjectives, for example An-225 article.Filip.vidinovski (talk) 09:32, 1 November 2021 (UTC)
 * As I said, even if a fact is easily and reliably verifiable it still doesn't always make it a good idea to include it, this is editorial judgement. The An-225 records are unlikely to be broken any time soon but this engine will be surpassed due to development, it's just a matter of time. Nimbus (Cumulus nimbus floats by)  10:18, 1 November 2021 (UTC)


 * Concur. The General Electric XA100 and Pratt & Whitney XA101 are both being developed to replace the F135 in some variants of the F-35, funding allowing, and both are intended to have greater thrust. And I assume the Russians amd Chinese may be working on more powerful engines also. BilCat (talk) 22:01, 1 November 2021 (UTC)

Fuel used for this engine
I've been trying to find out what fuel is used in the F-35B engine and I've not had much luck. I've heard both JP-5 and JP-8 but no search seems to come up with a result. They talk about thrust & weight but never about fuel type. Is there a source I'm missing and shouldn't it be either on the engine page or the F-35 page? CycloneSteve (talk) 03:31, 20 December 2023 (UTC)


 * The popular answer seems to be JP-8/F-34 which is supported by this photo of an F-35 being refuelled. Fuel type is a parameter of Template:Jetspecs but it's only meant for generic Avgas/Avtur types apart from a few exceptions that use exotic fuel like JP-7. One reason that fuel types are not generally listed in aircraft or aircraft engine articles even when known is that it could break WP:NOTGUIDE/WP:NOTMANUAL, we don't want ground crews and pilots checking Wikipedia for servicing their aircraft! Nimbus (Cumulus nimbus floats by)  15:00, 20 December 2023 (UTC)