# Catapults on Air Craft Carriers **URL:** \ **Category:** Factual Questions\ **Created:** [May 11, 2005, 2:08am UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329 "2005-05-11T02:08:41Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![mittu](https://avatars.discourse-cdn.com/v4/letter/m/ecd19e/32.png) [@mittu](https://boards.straightdope.com/u/mittu)\ **Post date:** [May 11, 2005, 11:33am UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/21 "2005-05-11T11:33:35Z")
My physics is incredibly rusty but assuming the height of the carrier (from deck to water) is around 50m (a bit of a WAG, the only measurement I could find was from keel to mast) I calculated it would take about 3.2 seconds for the Bradley to splash down after leaving the deck. Now assuming it leaves the deck at 120 m.p.h. I calculated that in 3.2 seconds it would travel about 171m before splashing. I’m know there are many amongst the TM that are far better at such things than I so I leave it up to them to tear apart my guess 🙂 One thing that confuses me, isn’t an M1 a tank? If so where was this tank that caused it to be hit by another tank being propelled from the deck of an aircraft carrier? Floating in the water? ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [May 11, 2005, 12:15pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/22 "2005-05-11T12:15:36Z")
Both the Brad and the M1 started below deck in the carrier. Then, after DODGING a blast from the M1 at about 20m with a skillful pivot steer, the hero drove the Bradley onto the elevator and got onto the deck. By the time the M1 was on deck, the hero rigs the Bradley to the catapult and launches it. The Bradley becomes a 50,000lb projectile and slams into the M1 (which was conveniently waiting in the path of the catapult). The M1 and the Brad both go flying off the carrier in a twisted mess of fire and steel. So this catapult not only launched a Bradley, but a Bradley “into” an M1 and then they BOTH were propelled off the deck. I wonder if this is still possible after we include the weight of the M1. ---
**Author:** ![Billdo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/billdo/32/315_2.png) [@Billdo](https://boards.straightdope.com/u/Billdo)\ **Post date:** [May 11, 2005, 12:31pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/23 "2005-05-11T12:31:15Z")
> [@Ringo](#): > > Ultimately, whether you could launch it or not, the Bradley ain’t gonna fly. As god is my witness, I though Bradleys could fly.[/WKRP] ---
**Author:** ![CynicalGabe](https://avatars.discourse-cdn.com/v4/letter/c/3e96dc/32.png) [@CynicalGabe](https://boards.straightdope.com/u/CynicalGabe)\ **Post date:** [May 11, 2005, 1:49pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/24 "2005-05-11T13:49:48Z")
Why were the tanks on the carrier to begin with? ---
**Author:** ![ElvisL1ves](https://avatars.discourse-cdn.com/v4/letter/e/5daacb/32.png) [@ElvisL1ves](https://boards.straightdope.com/u/ElvisL1ves)\ **Post date:** [May 11, 2005, 2:09pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/25 "2005-05-11T14:09:31Z")
> [@mittu](#): > > My physics is incredibly rusty but assuming the height of the carrier (from deck to water) is around 50m (a bit of a WAG, the only measurement I could find was from keel to mast) I calculated it would take about 3.2 seconds for the Bradley to splash down after leaving the deck. > > Now assuming it leaves the deck at 120 m.p.h. I calculated that in 3.2 seconds it would travel about 171m before splashing. Sounds roughly right. Anyway, catapulting a Bradley would indeed be an intensely satisfying experience for all spectators. ---
**Author:** ![August\_West](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/august_west/32/18069_2.png) [@August\_West](https://boards.straightdope.com/u/August_West)\ **Post date:** [May 11, 2005, 4:07pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/26 "2005-05-11T16:07:29Z")
When I as on the USS Enterprise during it’s extensive overhaul in the early '90s we did dead load testing on the cats. IIRC the dead loads were around 25000lbs. They were basically giant boxes with wheels, the corners were rounded but they weren’t terribly aerodynamic. They were launched out into the James River where a crane barge would pick them up. They flew pretty respectable distances, say around 150-200 yards. So based on the fact that an empty Bradley weighs 50000lbs, I would guess that a cat could launch one 75-100 yards ---
**Author:** ![mittu](https://avatars.discourse-cdn.com/v4/letter/m/ecd19e/32.png) [@mittu](https://boards.straightdope.com/u/mittu)\ **Post date:** [May 11, 2005, 4:17pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/27 "2005-05-11T16:17:52Z")
> [@August West](#): > > When I as on the USS Enterprise during it’s extensive overhaul in the early '90s we did dead load testing on the cats. Anyone else have a mental image of felines being propelled into the sea? :eek: ---
**Author:** ![FordPrefect](https://avatars.discourse-cdn.com/v4/letter/f/e99b99/32.png) [@FordPrefect](https://boards.straightdope.com/u/FordPrefect)\ **Post date:** [May 11, 2005, 4:47pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/28 "2005-05-11T16:47:21Z")
> [@David Simmons](#): > > Is the launch force of the steam catapults adjustable to account for aircraft of different take-of weights? Or isn’t it worth the trouble? According to one fighter plane book I read as a youngster the thumbs up that the pilot gives the ground crew before being thrown over the edge means that they confirm the takeoff weight that the catapult guy is showing them on a board. This may have changed in the last 15 years, but that is what the book said. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [May 11, 2005, 4:58pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/29 "2005-05-11T16:58:57Z")
> [@Ringo](#): > > Ultimately, whether you could launch it or not, the Bradley ain’t gonna fly. This reminds me of a quote from (I think) the movie Top Gun where the CO mentions something to the effect that the F4 Phantom proves that even bricks can fly if you give them a big enough engine. Somehow seemed appropriate for a discussion on a flying Bradley. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [May 11, 2005, 4:59pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/30 "2005-05-11T16:59:37Z")
I had about nineteen different Monty Python quotes pop into my head as I read this… “Perhaps if we built a large badger…” “It’s more of a plummet, actually. Not a creature of the air is the Bradley.” “I fling her.” ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [May 11, 2005, 5:19pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/31 "2005-05-11T17:19:01Z")
The aircraft IS at flying speed (above stall) when it leaves the flight deck. However, there is sufficient weight on the nose wheel that elevator authority needed to lift the nose to take off attitude is not available until significantly above stall speed. Once it drops off the end of the deck, the elevators need only rotate the aircraft about it’s CG against it’s rotational moment, rather than levering the nose up against gravity on the fulcrum of the main gear like when it was on the deck. This takes a half second or so before the aircraft rotates to a climbing attitude. And THAT is why the aircraft drop off the end of the deck before climbing. ---
**Author:** ![mhendo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mhendo/32/3159_2.png) [@mhendo](https://boards.straightdope.com/u/mhendo)\ **Post date:** [May 11, 2005, 5:31pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/32 "2005-05-11T17:31:48Z")
> [@David Simmons](#): > > Is the launch force of the steam catapults adjustable to account for aircraft of different take-of weights? Or isn’t it worth the trouble? Yes, it’s adjustable, and is apparently adjusted for each launch depending on the type of plane etc. You can read about the procedure [here](http://people.howstuffworks.com/aircraft-carrier4.htm). From the link: > [@](#): > > When the plane is ready to go, the catapult officer opens valves to fill the catapult cylinders with high-pressure steam from the ship’s reactors. This steam provides the necessary force to propel the pistons at high speed, slinging the plane forward to generate the necessary lift for takeoff. Initially, the pistons are locked into place, so the cylinders simply build up pressure. **The catapult officer carefully monitors the pressure level so it’s just right for the particular plane and deck conditions. If the pressure is too low, the plane won’t get moving fast enough to take off, and the catapult will throw it into the ocean. If there’s too much pressure, the sudden jerk could break the nose gear right off.** ---
**Author:** ![Padeye](https://avatars.discourse-cdn.com/v4/letter/p/a9a28c/32.png) [@Padeye](https://boards.straightdope.com/u/Padeye)\ **Post date:** [May 12, 2005, 1:28am UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/33 "2005-05-12T01:28:15Z")
> [@Kevbo](#): > > And THAT is why the aircraft drop off the end of the deck before climbing. They don’t drop significantly with a normal cat shot, at least that was my obvservation when I worked flight deck for nearly two years as a final checker. This is true even with F-14s which are launched in a negative pitch attitude due to the kneeling nosegear. The tail end does drop but only enough topitch up and put the plane in a positive attitude. If a plane drops much at all that is an indication of a cold cat shot. I found a cite on the NASA/JPL website that probably has more than you wanted to know about the physics of a catapult. Note that it is an Adobe .pdf file [http://pumas.jpl.nasa.gov/PDF\_Examples/03\_23\_02\_1.pdf](http://pumas.jpl.nasa.gov/PDF_Examples/03_23_02_1.pdf) I only got to take one trap, in a C-2 Greyhound like **Mr Moto** flew in. Because the seats in the cargo bay are backwards you feel like you have been thrown onto your back and launched upward when you catch the arresting cable and that is pretty mild compared to a jet. I only got to take one cat shot, in a US-3A “Miss Piggy”, a convereted Viking for COD use. Best &%$#ing carnival ride ever. 😃 ---
**Author:** ![pullin](https://avatars.discourse-cdn.com/v4/letter/p/c57346/32.png) [@pullin](https://boards.straightdope.com/u/pullin)\ **Post date:** [May 12, 2005, 2:36am UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/34 "2005-05-12T02:36:49Z")
> [@mhendo](#): > > Yes, it’s adjustable, and is apparently adjusted for each launch depending on the type of plane etc. > > You can read about the procedure [here](http://people.howstuffworks.com/aircraft-carrier4.htm). > > From the link: IANANP: But don’t they also do the same thing when they land? Calculate the landing weight in order to dial in X amount of tension on the arresting gear? Seems reasonable, anyway. (NP = Navy Pilot) ---
**Author:** ![pilot141](https://avatars.discourse-cdn.com/v4/letter/p/e0b2c6/32.png) [@pilot141](https://boards.straightdope.com/u/pilot141)\ **Post date:** [May 12, 2005, 3:35am UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/35 "2005-05-12T03:35:37Z")
(I can’t believe I’m doing this) 🆒 **Pullin** the correct term is Naval Aviator, as any Navy puke will loudly and repeatedly tell you. Only the Air Force has Pilots. Pilot and proud of it! ---
**Author:** ![Padeye](https://avatars.discourse-cdn.com/v4/letter/p/a9a28c/32.png) [@Padeye](https://boards.straightdope.com/u/Padeye)\ **Post date:** [May 12, 2005, 4:05am UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/36 "2005-05-12T04:05:07Z")
Yes, the arresting gear which are hydralic cylinders need to be calibrated for each kind of airplane. In late '81 I witnessed the consequences of not having the arresting gear set correctly. My sqadron CO was on approach to the Constellation in an F-14. He came in a little high but that’s better than too low. You can bolter and go around if you miss the wires but you don’t walk away from a ramp strike. The plane caught the last arresting gear cable, the four wire and kept right on going. We were told later that the arresting engine, a big hydralic cylinder that works like a screen door closer, was set for a lighter aircraft. The normal procedure for landing is for the pilot to go to military power, that is full throttle but no afterburners the second the wheels hit the deck. This is so that if they bolter, miss the wires, they can just take off again for another attempt. In this case the arresting gear didn’t slow down the plane enough to stop it before it reached the angle deck. It did slow down the plane so that it was well below stall speed so when it reached the limit of the cables spooling out of the arresting engine the intertia of the plane pulled the cables completely out of the deck. The plane went down like a stone. All we saw after it went below deck level, about 65 feet above the water for the Connie, was the canopy being jettisoned then a splash when the plane hit. We learned the rest of the story from the crew. The skipper in the front seat was reaching for the face curtain ejection handle but the RIO pulled the secondary handle between his knees first. A lot of stuff has to happen in the ejection sequence from the explosive bolts that release the caonpy to the parachute ride to the water. Because the plane was falling it’s downward velocity was subtracted from the seat motors so it was an out of envelope ejection. The pilot’s seat was launching from the plane as it was striking the water and he had barely separated from his seat before he hit the water. Neither parachute opened but the crew were okay except for the skipper having a sore neck because his head was tipped forward when he ejected. The plane guard helo picked them up in a matter of minutes and had them back wet but alive. Scared the holy hell out of us working the line that day. We didn’t realize it was an arresting gear failure on the ship. I had changed tail hook points on planes that morning including on that plane and for a while I thought I might be responsible for the death of two officers and loss of a plane. ---
**Author:** ![Lord\_Mondegreen](https://avatars.discourse-cdn.com/v4/letter/l/91b2a8/32.png) [@Lord\_Mondegreen](https://boards.straightdope.com/u/Lord_Mondegreen)\ **Post date:** [May 12, 2005, 7:11am UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/37 "2005-05-12T07:11:30Z")
> [@Padeye](#): > > I once saw a takeoff incident where the pilot, my squadron XO at the time, forgot to release the parking brake for takeoff. 32 tons of metal and wheels that won’t turn. The cat launched the plane to the same airspeed as if the wheels had been turning. Note that the main tires on an F-14 are about three feet tall and for carrier use are inflated to 300psi. This is how the XO earned the nickname “Boom-Boom Bertsch.” 😃 He was okay. Although he could have trapped with two blown tires everyone decided it was safer to bingo to the beach. I’m glad he was OK, but I need to know the details! If he reached adequate airspeed I’m guessing he flew away rather than ditching off the end off the carrier? With the blown tires did he have to eject, or proceed to an airport and land on foam? (The answer may be contained in the phrase “bingo to the beach” - I’m not familiar with that expression.) ---
**Author:** ![sewalk](https://avatars.discourse-cdn.com/v4/letter/s/b3f665/32.png) [@sewalk](https://boards.straightdope.com/u/sewalk)\ **Post date:** [May 12, 2005, 8:09am UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/38 "2005-05-12T08:09:10Z")
> [@pilot141](#): > > (I can’t believe I’m doing this) 🆒 > > **Pullin** the correct term is Naval Aviator, as any Navy puke will loudly and repeatedly tell you. > > Only the Air Force has Pilots. Get it straight before you correct others: In naval parlance, a pilot is a sailor (usually civilian, I think), who guides a vessel into a harbor or other restricted waters. Many Navy pukes look on them as glorified parking attendants since they don’t often venture out of sight of dry land. Aviators, when not dragging their knuckles or drooling on their flight suits, like to differentiate themselves from the rest of the naval service. ---
**Author:** ![Padeye](https://avatars.discourse-cdn.com/v4/letter/p/a9a28c/32.png) [@Padeye](https://boards.straightdope.com/u/Padeye)\ **Post date:** [May 12, 2005, 1:43pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/39 "2005-05-12T13:43:16Z")
> [@Lord Mondegreen](#): > > I’m glad he was OK, but I need to know the details! If he reached adequate airspeed I’m guessing he flew away rather than ditching off the end off the carrier? > > With the blown tires did he have to eject, or proceed to an airport and land on foam? (The answer may be contained in the phrase “bingo to the beach” - I’m not familiar with that expression.) My technical writing instructor in college told me to avoid jargon. You can see how much attention I paid. The only thing harmed in that incident were a pair of Goodyear tires. Yes, he reached the same airspeed he would have if the wheels were rolling. The friction of the tires was trivial compared to the force of the catapult. Remember that once something is sliding it has much less friction than when static. That’s why the shortest stopping distance is when the tired are just at the edge of locking up rather than being completely locked. Bingo means to land on shore rather than the carrier where he landed normally. Funny but I never heard of landing on a foamed runway except in movies. If he had to land on the ship I think he may have attempted a normall arrested landing but they might also have used a barricade. The modern barridcade is a big net made of heavy nylon webbing which is attached to a fifth arresting gear wire just for that purpose. The portion of the cable that is streched across the deck before it is pulled out is a replacable section called a crossdeck pendant. When rig the barricade is called everyone on the flight deck drags out the barricade and attach it to the retractable parts of the cable and a pair of masts that are normally folded into the surface of the deck to raise it vertically. The plane flies into the barricade which catches the wings and anything else that snags on the vertical straps. [![](http://www.navsource.org/archives/02/026322.jpg) ](http://www.navsource.org/archives/02/026322.jpg) ---
**Author:** ![Inigo\_Montoya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/inigo_montoya/32/124_2.png) [@Inigo\_Montoya](https://boards.straightdope.com/u/Inigo_Montoya)\ **Post date:** [May 12, 2005, 2:11pm UTC](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329/40 "2005-05-12T14:11:05Z")
[Boromir] We could build a [catapult](http://www.newcomicreviews.com/temp/lotr/catapult1id.gif)… [/Boromir] [Previous page](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329.md?page=1) [Next page](https://boards.straightdope.com/t/catapults-on-air-craft-carriers/303329.md?page=3)