Talk:Aircraft catapult

Color drawing upload?

I have a color drawing showing the internal subsystems of a steam cat, but I do not know how to incorporate it in the article or whether it is good enough for incorporation. Please advise. - Schnaz 15:38, 31 August 2006 (UTC)

Use the "Upload file" link on the sidebar to the left (in the "toolbox" section) to upload it to Wikipedia; you will need to release it under an appropriate license. Then, include in the article an image link: e.g. [[Image:Steam_catapult.png|thumb|right|Internal subsystems of a steam catapult]] (see Help:Image). Don't worry about whether it is good enough; as long as it's factually correct other editors will be able to improve it. EdC 13:53, 2 September 2006 (UTC)

The image that I uploaded didn't pass muster. The fair-use nazis quashed it. I've had it in my archives for 20 years, and I'm 99.9 percent certain it was provided to the US Navy under a contract, which means it's Uncle Sam's, which means it's in the public domain. But I guess unless I prove that, the image can't be used. -Schnaz 22:03, 3 September 2006 (UTC)

Aircraft Carrier Steam Catapult

Is this the drawing in question? It's been sitting there unlinked since 31 August 2006, but I don't see any evidence of the "fair-use nazis" quashing it. It's of such low quality that it's virtually useless. Is there any way it could be re-uploaded as a PNG file, 24-bit color (16.7 million colors) at 300 dpi or better resolution, so that even the smallest text is readable? Stay away from JPEG, due to loss of detail from compression artifacts, and GIF, as that format is limited to 256 colors and also results in pixel artifacts when colors are dithered. Once a clean scan is available, a Wikipedian with an artistic bent could either clean it up more, or use it for the basis of an SVG line illustration. This would be better than what we have now, which is precisely nothing.—Quicksilver^{T @} 00:50, 21 April 2010 (UTC)

I will see whether I can dig up a drawing that's at least 300 dpi. I don't think the color depth is that important, since even four colors would probably be sufficient to get the point across. Will advise. Schnaz (talk) 00:16, 10 May 2010 (UTC)

This appears to be a "manual" for a steam catapult, with detailed drawings of all the elements: https://www.globalsecurity.org/military/library/policy/navy/nrtc/14310_ch4.pdf . — Preceding unsigned comment added by 130.221.224.7 (talk) 18:36, 27 February 2019 (UTC)

Discussion

Don't most catapult launches now come off nuclear-powered carriers? I suppose they have adequate electrical power but I understood they still used steam. The conformation of the catapult tube is similar to that used in Brunel's atmospheric railway (and presumably the Irish one that predated it), but the sealing strip is all steel. Midgley 16:23, 4 March 2006 (UTC)

Nuclear-powered ships still use steam for propulsion, the only difference is that the heat to generate the steam comes from a nuclear reactor rather than a coal or oil-fired furnace. PeteVerdon 16:37, 9 April 2006 (UTC)

I should perhaps have explicitly said - so the section "An important factor driving the conversion to electromagnetic catapults is the steady conversion of warships from steam power to gas turbine power, and the resultant loss of readily-available high-pressure steam" is perhaps not correct or relevant? Midgley 16:39, 9 April 2006 (UTC)

Come to that, I don't have a copy of Jane's but I can't recall and there is no actual reference to any instance of an electric catapult. Is there one on a carrier? Midgley 16:40, 9 April 2006 (UTC)

There was meant to be an electric catapult on CVX/CVN-21/CVN-77. According to a 2005 Navy press release, they are still in the design.

Advance Construction Begins for CVN 21

Navy NewsStand

Story Number: NNS050812-13

Release Date: 8/12/2005 1:57:00 PM

MilesVorkosigan 17:46, 12 April 2006 (UTC)

EMALS (Electro-Magnetic Aircraft Launch System) is still in development at NAES Lakehurst. The first test model is being constructed there. Also, it's worth noting that low-pressure steam cats -- as opposed to high-pressure systems -- have been in operation since about 1989. Schnaz 13:51, 22 June 2006 (UTC)

There is no plan to switch from using nuclear power/steam to gas turbine to propel U.S. aircraft carriers. The move away from steam cats to EMALS had nothing to do with ship's propulsion.E2a2j (talk) 19:00, 24 April 2010 (UTC)

Agree- move to Electric has nothing to do with propulsion, it will be less maintenance, therefore cheaper in long run. - Ok for US carriers, isn't there a steam accumulator as part of the system for a steam catapult. Will EMALS also have a larger accumulator (since electric - a BIG capacitor bank).EMALs/electric - somewhere I have impression steam cannot be "dialed" back significantly for smaller/lighter aircraft, and EMALS will offer this. Wfoj3 (talk) 23:48, 5 December 2013 (UTC)

Launch frequency

As far as I remember (sorry -- the mind is a bad source) An American aircraft carrier can launch 2 aircrafts per minute per catapult (they have 4 catapults altogether). In order to get to air speed (e.g. 280 km/h and a way of 80m => around 4 G force effect). —The preceding unsigned comment was added by 172.183.93.118 (talk) 16:58, 5 May 2007 (UTC).

Not true. US aircraft carriers can launch aircraft about every 2-3 minutes per catapult. After an aircraft has launched, it takes time to taxi another aircraft onto the cat, hook it up, arm it, and go through final checks. 4g's sounds about right. E2a2j (talk) 17:43, 7 October 2008 (UTC)

Bridle catchers

Nice inclusion. Should perhaps later add a section about last types of Aircraft that used the bridles. I believe the last type of aircraft to use the bridles was the T-2 Buckeye, a small two seat 2 jet trainer, now replaced by the T-45. Unsure what was the last type of tactical aircraft utilized that used the bridles. Wild guess between the A-7 Corsair, or early variants of the A-6 Intruder, or perhaps A-4 Skyhawk. Wfoj2 23:51, 28 December 2006 (UTC)

T2 was the last bridle aircraft. A4 before that. A7 and A6 used launch bar. F4 was the last fighter to use bridle.E2a2j (talk) 19:02, 24 April 2010 (UTC)

History section

Also, someone screwed with the History section. It has bits that just go "jhas asdh a is asrha v[[]" and such. Would someone knowledgeable please fix it up? —Preceding unsigned comment added by 208.114.167.19 (talk • contribs) 23:51, 26 March 2007

Someone who knows what they're doing, could you please fix the gibberish? It really detracts from the article. —The preceding unsigned comment was added by 208.114.167.19 (talk) 23:53, 26 March 2007 (UTC).

The last sentence of the first History graph states: "Some upcoming carrier designs . . . include electric catapults in their plans."

Should that be "electromagnetic catapults"? -- Schnaz 18:23, 28 March 2007 (UTC)

HMAS Australia was not a Royal Navy (RN) ship, it was a Royal Australian Navy (RAN) ship (hence HMAS rather than HMS). It was however attached to the British Grand Fleet (along with several cruisers) in the North Sea 1915-1918 (after the destruction of the German East Asian squadron left no serious enemy threat in the Pacific or Indian oceans). 1.129.97.93 (talk) 12:51, 15 July 2016 (UTC)

Other types of catapult

Shouldn't there be a section on WWII catapults, of the rocket and explosive kind for CAM and MAC ships, and the counterweight, mechanical kind used on cruisers and battleships? KTo288 19:59, 11 August 2007 (UTC)

Operation section

I've taken the liberty of adding an "operation" section based on a fairly detailed article published a few years ago in the UK.

The original Atmospheric Railway was not in Devon but in Ireland therefore any supposition about it being connected with The brunel railway application is tenuous. Does anybody know where those US Navy photos cited in the referenced external article live? Getting one or two of those into the article- particularly the line drawing- could add a lot. MarkMLl 11:13, 9 September 2007 (UTC)

The new section looks good, but you need to cite your source in the text. we can help with the formatting if you aren't sure how to do it. - BillCJ 17:33, 9 September 2007 (UTC)

Thanks Bill, I haven't got the source material to hand but when I have- which could be a few months- I'll come back and add a reference and correct anything that doesn't look right. MarkMLl 20:57, 10 September 2007 (UTC)

The operation section should be modified slightly. I don't have a source to give you, as it's based on my own operational experience as the steam catapult supervisor on the Nimitz for 2+ years. The steam accumulators there don't operate quite the way they do in the linked wiki article. First off, they are pressurized to 600psi and operate at about 480F (saturation temperature of water at that pressure). They are heated by the ships 600psi auxiliary steam system. They don't accumulate steam, so much as they accumulate really hot water. The majority of steam that goes into a catapult cylinder at launch is actually the result of flash conversion when the launch valve is opened, because the volume of steam actually in the accumulator would not be enough. The tank levels are closely monitored during launch operations and manually refilled from the ships main engineering water supply (which is already pressurized and heated).-- Zogblog (talk) 23:00, 10 March 2008 (UTC)

F-18 photo at start of article

The nose of the plane appears to be much sharper than the tail. I don't think it's a focus problem, if it were a mechanical camera with a focal plane shutter I'd say that it indicates how much speed the plane had picked up while the curtains were crossing the film- that would almost knock it into the "featured photo" bracket. MarkMLl 20:57, 10 September 2007 (UTC)

Cylinder slot seal

Precisely how is the slot in the cylinder sealed? I've wondered about this for many years! LorenzoB (talk) 05:27, 4 February 2008 (UTC)

I believe it's accomplished with a flexible spring steel band that lies in rabbets on the inside of the cylinder slot. The band may be secured to the cylinder wall on one edge and free to move on the other. The cylinder forms a nearly-closed "C" shape in cross-section and is fabricated such that the loss of hoop strength through the gap in its circumference is compensated. As the cylinder is pressurized with steam, it forces the steel band tightly against the rabbet surface, forming a fairly effective seal along the entire length. As the piston travels along the cylinder, propelled by steam pressure, a plate with gradual tapers at the front and back edges reaches from the inside of the cylinder to the outside, past the steel band, to propel the shuttle that slides in a slot on the deck. There is a little leakage where the tapers end, as evidenced by the wisp of steam that is always visible as the shuttle is moving, but the rest of the band, being non-moving against the cylinder body, makes a highly effective seal. Think of it as the overlap of the seams of a button-front shirt: If you unfasten the buttons, keeping your palm against your chest, you can easily slide your fingers up and down between the shirt edges, barely separating the seams from each other, yet your hand is reaching from the outside of the shirt to the inside.
The link to the "Atmospheric railway" article provides some insight, but is at the same time misleading. Atmospheric railways operated on vacuum, not atmospheric overpressure, so their sealing mechanism was different. They had to resist the efforts of the atmosphere at 15 psi, maximum, trying to push the seal into the cylinder, not keep several atmospheres of internal steam pressure trying to blow the seal outward. They used a leather flap reinforced with a steel bar and sealed with a goo that would be melted by charcoal heaters on the underside of the railcar, then pressed back into place with steel rollers and allowed to cool to reestablish the seal — messy, and obviously impractical for an aircraft catapult.
Conceivably, a seal could be formed by sliding a spring steel band back and forth with the shuttle, similar to that of a pocket tape measure, but that would produce a lot of friction and the band would need to be coiled up on drums at both ends. One little hiccup, and it would look like a reel-to-reel tape recorder that had a tape spillage problem. That would obviously not be practical.
Some small rodless pneumatic cylinders, such as those from Tol-O-Matic, use magnets to hold a stainless steel sealing band in place.[1] They're sized to open and close a sliding door on a building entrance or move a gadget on a machine tool or assembly line, that sort of thing, but not to catapult an aircraft. However, it's conceivable that the magnet idea might be applicable to holding the seal in place on a steam catapult as well. Although superheated steam is really hot, the temperatures inside the cylinder are probably below the Curie point, so loss of magnetization wouldn't be a problem.
It's too bad we don't have a definitive description here. I've seen photos of steam catapult overhaul crews at work, but they've always been set so one couldn't see the piston, cylinder and seal details. There may be some aspects about shipboard steam catapults that are still considered classified.—Quicksilver^{T @} 00:00, 21 April 2010 (UTC)

There's an original 1960 RN training film called Launch and Recover, showing steam catapult technical details, including the slot sealing method, on YouTube here: [2] The carrier BTW, is Hermes. — Preceding unsigned comment added by 80.7.147.13 (talk) 16:53, 29 May 2012 (UTC)

Catapults used by Langley & the Wright Brothers

while known to history of aviation buffs both Langley & ther Wrights used catapults. Langley on his failed man-carrying 'aerodrom' Oct. & Dec. 1903. He'd also used spring operated catapults on his earlier model 'aerodromes'(Langley's term) beginning in the early 1890s. The Wrights usage of a 1,600 pound weight falling from the inside of 20 foot high derrick is a little more well known. The brothers began using this device in September 1904 but their aircraft were capable of taking off without the catapult. Koplimek (talk) 04:37, 1 May 2008 (UTC)

If it's "known to history of aviation buffs", you should not have any problem finding reliable sources to cite. Please remember that reliable sources must be provided when an addition is challenged, and that it is up to the contributor to provide the sources. - BillCJ (talk) 09:08, 1 May 2008 (UTC)

I have started to work on this page

could use some help if anyone is interested.jacob805 —Preceding unsigned comment added by 83.64.176.178 (talk) 09:36, 6 January 2009 (UTC)

Bridle catchers in introduction

The introduction refers to the elimination of bridle catchers but does not mention when they were introduced. Indeed, it makes it sound as if bridle catchers were standard CV equipment from the beginning. They were not; catchers were introduced some time in the 1950s (before then, the bridles went flying into the ocean and were lost). I do not know precisely when the catchers were introduced, else I'd add it. If anyone reading this has that info, please add it. 165.91.64.227 (talk) 01:25, 28 January 2009 (UTC)RKH

Lufthansa seaplane tenders

Not a "claim", as a source was given, the ships in question were the Westfalen operated by the Norddeutsche Loyd and the Schwabenland, opereated by DDG Hansa on Behalf of Lufthansa. —Preceding unsigned comment added by 188.192.180.244 (talk) 19:17, 13 December 2009 (UTC)

Actually 4 ships that managed the AirMail connections from Germany/Europe to West Africa and South America. conversion of merchant men vessels started in 1932, regular services began in 1933, continuously operated into the start of WWII. Landings were onto the water and a helper dragged sail. Start via steam catapult ( but arthwartship ) some images and ancillary information: http://www.steelnavy.com/1250DLHships.htm nothing experimental about it. —Preceding unsigned comment added by 91.39.236.163 (talk) 11:55, 19 July 2010 (UTC)

Aircraft launch at moment of leaving the flght deck

If the catapult pulls the airplane forward, whats unclear to me is: How is the airplane able to disengage from the catapult without damage to either the airplane or the catapult? What is the mechanism which allows for easy and quick release of the aircraft from the catapult? Hashtag comment: Haven't fighter jets become so fast to have made catapults obsolete? Marc S. Dania Fl 206.192.35.125 (talk) 14:42, 28 August 2013 (UTC)

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Landing

Hi BilCat, I award you points for your rather witty edit summary ("catapults aren't used to land aircraft"). However, the sentence I added ("Catapulted aircraft land like conventional aircraft, sometimes with the help of arresting gear.") clearly did not say a single thing about this, i.e. landing aircraft with the help of a catapults, but in the contrary! Don't you agree with me that when the article talks in great lengths about this special method to help an aircraft takeoff aboard an aircraft carrier, it should at least hint at the concept of landing, especially when there's another special system called arresting gear for that task? Thanks, --Gnom (talk) 08:08, 27 October 2014 (UTC)

No, not really. This article isn't about carrier operations, for which there is an article, just catapults. But I did link to Arresting gear in the "See also", where it probably should have been already. I hope that helps. - BilCat (talk) 08:26, 27 October 2014 (UTC)

carrier history zaprdude@optonline.net I am electronics technician, not a linguist-what a struggle for me!

While stationed on CV11 from June 1954 to Nov1956,I witnessed the testing of steam catapults of British design while docked at Portsmouth  Naval Shipyard during summer 1954. The installation was successful ,launching dead loads 
 of up to ,I believe,100,000 lbs. Protrusions were built to catch the launching cables,and later removed.  — Preceding unsigned comment added by 69.115.143.25 (talk) 01:37, 12 June 2015 (UTC) 

Merger proposal/Closed

No need for a separate article!!--Petebutt (talk) 01:45, 26 July 2015 (UTC)

• Comment: Just to be clear we are talking about All American Turbo-Cat. At first glance the Turbo-Cat seems to fall under the scope of aircraft catapult. But can someone with technical expertise confirm this? Was the Turbo-Cat a Form of a Catapult or an alternative? DaltonCastle (talk) 19:13, 25 August 2015 (UTC)

Merger proposal/closed

Proposal to merge Electromagnetic Aircraft Launch System with this article.

• Closed not enough consensus to merge. Reb1981 (talk) 22:50, 28 July 2016 (UTC)

• Merge - I believe this article should be merged. All other forms of an Aircraft catapult are included. There is no need for a seperate article. Reb1981 (talk) 22:07, 19 June 2016 (UTC)

• Opppose - EMALS article is long enough that merging would involve cutting it down a lot. What is there is fairly well sourced, and cutting out any fluff probably wouldn't help that much either. In addition, the EMALS article is more about a specific design of electromagnetic catapult. The fact that articles on hydraulic and steam catapult types don't exist is probably more the result of a lack of quality online sources than anything else. I'd much rather see articles on those types created and expanded, which would include lists/tables of individual types currenly in this article, rather than merging everything into one large, bloated article. - BilCat (talk) 22:51, 19 June 2016 (UTC)

• Merge - The proposition seems legit. Since both Electromagnetic Aircraft Launch System and Aircraft catapults are in the same area of topics. (N0n3up (talk) 04:07, 20 June 2016 (UTC))

• mild Oppose as per BilCat's argument. Gecko G (talk) 20:29, 24 July 2016 (UTC)