Guest livewire23 Posted December 18, 2003 Share Posted December 18, 2003 I'm only into my second semester as an aerospace engineer, but I think I ought to point out that the aerodynamics of a Z really wouldn'y take well to an attempt to make it hit supersonic speeds. At supersonic speeds the air around the leading edge of the Z would be compressed so much that it's be like trying to force a Z through a brick wall. All the crush zones would crush, the glass would break, and those Z headlights would be gone. My professional reccomendation: Headlight covers and a COMBAT ricer wing. One of the double tiiered ones. Car'd still get crushed halfway to hell, but at least it'd generate some lift Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted December 18, 2003 Author Share Posted December 18, 2003 If you turned the car around, it would have a profile more like an airfoil, and the car would be more like a lifting body craft, so maybe we should do that to get it to 'fly' farther. I have difficulty seeing how the car could go 3,000 MPH from the catapult. I don't think it was designed to go more than like, 250/300 MPH? Reguardless of the weight of whatever you're launching. At only 2500 Lbs., it'd still be an easy thing for the catapult to do... Quote Link to comment Share on other sites More sharing options...
BillZ260 Posted December 18, 2003 Share Posted December 18, 2003 One other thing, what exactly are you going to attach the CAT to on the Z? I can only imaging what 60K Lbs of thrust would do to the almost aluminum like unibody material. I think it would move about 3 ft after the cat ripped the thing in half... Quote Link to comment Share on other sites More sharing options...
silicone boy Posted December 18, 2003 Share Posted December 18, 2003 If you read Pete P's article on unibody reinforcement and install a roll cage, you should be fine as far as being able to stand up to the G forces a catapult would subject you to. Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted December 18, 2003 Author Share Posted December 18, 2003 I think you'd have to attach a ladder-like frame to the chassis, so the whole car gets going as a whole. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted December 18, 2003 Share Posted December 18, 2003 Based on what Phantom said my guess is that the cats are limited to a max launch speed of ~160mph so things don't break as often. This doesn't stop us from doing the calculations based on the forces generated in launching a 60' date='000 lb aircraft at 150 mph Just as a quick calculation you could divide the weight of a Z into the 60,000 lbs 60,000 / 2,700 = 22.22 Then multiply that times 150 mph to get the unlimited velocity the Z would reach 22.22 * 150 = 3,333.33 mph. Based on the afore mentioned 3 second flight time the car would go ~2.77 miles. Not quite the 30 miles mentioned before but still a very long distance. You would also get a nice sonic boom on launch. These calculations obviously ignore aerodynamic factors so the distance would probably be half that, I'll leave that for someone else to figure out. Ken W.[/quote'] Yes, Force = Mass times Acceleration, so subjecting a smaller mass to the same force will result in a larger acceleration. But by your logic dry firing the cat with no weight will yield an infinite terminal velocity. The correct answer is the cat will only hit some maximum terminal velocity (160 MPH?) no matter what is connected to it. Shipyards regularly do catapult testing by launching a dumpster full of water. So launching a car would be no big deal. The distance the car will travel will be exactly the same as if you drove the car off a 70 foot cliff at the same speed. Assuming no lift, the time for the car to drop 70 is governed by the equation distance = one half a t squared, or about 2 seconds fall time. At 160 MPH thats about 450 feet. Lift will make the car take longer to hit the water, but will also slow the car as it travels. Thus 300-400 feet is my guess. Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted December 18, 2003 Author Share Posted December 18, 2003 You forgot the launch ramp at the end of the deck for some extra distance & height! Quote Link to comment Share on other sites More sharing options...
Guest livewire23 Posted December 18, 2003 Share Posted December 18, 2003 too many bored engineers. Quote Link to comment Share on other sites More sharing options...
Chaparral2f Posted December 18, 2003 Share Posted December 18, 2003 I t hionk I read once where the Nimitz could launch a VW about a quarter mile before it hit the water. Quote Link to comment Share on other sites More sharing options...
baddriver Posted December 18, 2003 Share Posted December 18, 2003 You guys are crazy! Hilarious, but crazy. This is just the post to pick me up, I'd been having a dull day, and I really got a kick out of this discussion. Not jus the subject, but the fact that dozens of people logged in to talk it out, even gave some thought to the aerodynamics. And I thought fark.com was funny! This is definately my favorite site in the www. Later, Jeff Quote Link to comment Share on other sites More sharing options...
Phantom Posted December 18, 2003 Share Posted December 18, 2003 Guys -cats will NOT accellerate an object over about 180 mph no matter how light it is. They are designed to adjust for varying wieght and then launch that weight to a fairly narrow speed range of 140-180 MPH. BAck to my original 350' estimate. Besides - once you've seen it done it's hard to go along with "calculations" that don't correespond with the eyeball. Quote Link to comment Share on other sites More sharing options...
wheelman Posted December 18, 2003 Share Posted December 18, 2003 I wasn't saying the cat WOULD throw the Z at 3,333 mph, but that theoretically based on the capability to launch a 60,000 lb aircraft at 150 mph, it COULD. Based on what has been said the cats obviously have to be limited to a max speed otherwise they would tear themselves apart as well as the aircraft. Just like our Z's do when we put to much HP/Torque (if there is such a thing) into them. Also as has been said, the Z itself would never withstand that kind of acceleration or aerodynamic force. But it is fun to speculate on how far we could throw one if limits on the equipment were removed. Kind of like analyzing Hollywood movies from a physics stand point. Ken W. Quote Link to comment Share on other sites More sharing options...
Corzette Posted December 19, 2003 Share Posted December 19, 2003 LMAO!!!!! Hey if we attached it to the space shuttle it could go 17,000 MPH plus in space! Better replace those door seals though! CZ Quote Link to comment Share on other sites More sharing options...
Bob_H Posted December 23, 2003 Share Posted December 23, 2003 As a "current" Nasal radiator,(Naval aviator..) Phantom hit it on the head. The weight is merely a part of the equation. Depending on the plane being launched, the end speed is anywhere from 135ish for a S-3 to about 160ish for a F/A-18. BTW, that is Knots, so add a few for MPH. If they compute it wrong, and say they think they are shooting a 50,000 lb load but are actually shooting a 15,000lb load, they will likely break the cat at the end of the shot. The water brake at the end can only take so much force. To give you and idea, you can feel the ship shake when the catapult hits the end of the shot. And the Carrier is over 1000 feet long and displaces over 95,000 tons.... Whoops, see others now covered it. -Bob Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted December 24, 2003 Author Share Posted December 24, 2003 I guess Bob settled that one for us. Bob-- do you remember if they really shoot cars off the cat, or dumpsters of water? What's your favorite car shot? Quote Link to comment Share on other sites More sharing options...
Bob_H Posted December 24, 2003 Share Posted December 24, 2003 I can't take full credit for that. Phantom gave the same answer I did, just in a slightly different way. Yes, they do shoot odd things from cats. In the initial testing, they shoot a lead sled,(actually a weighted sled). I think it is a 5000lb sled, but can't recall exactly. And more recently, They shot an old plymouth or something like that from one of the operational carriers. So you can shoot cars, and they have. If I recall, it went a few hundred feet. The carrier was barely moving at the time so no, it didn't run it over... I expect the end speed was around 80-100 mph. -Bob Quote Link to comment Share on other sites More sharing options...
TomoHawk Posted December 24, 2003 Author Share Posted December 24, 2003 I would say they had the ship inching along slowly. Probably not from fear of hitting the car. From model ship competition, I know that you don't want something that big sitting still. The wind could blow it around and it could end up pointing in the wrong direction . Also, it takes a lot more power to get it moving from a stand still than it does from a slow rolling start. I'll think up something else that's fun to discuss Next year. Are we all discuss-ted about this now? Quote Link to comment Share on other sites More sharing options...
Bob_H Posted December 24, 2003 Share Posted December 24, 2003 ....The wind could blow it around and it could end up pointing in the wrong direction . Also' date=' it takes a lot more power to get it moving from a stand still than it does from a slow rolling start.[/quote'] welll........the wind has very little effect on the ship, if at all. But for a reference, minimum steerage on the carrier is about 2-3 knots. And for as large as it is, it gets up to speed in a "relatively" quick amount of time. Stopping does take some time..... Yea, I think we have discusse-ted this one enough. Quote Link to comment Share on other sites More sharing options...
DavyZ Posted December 24, 2003 Share Posted December 24, 2003 So I take it the cars they shoot off the deck just go down to the bottom of the sea? Wow, if they don't bother recovering cars, I can imagine a National Geographic special in which Jacques Cousteau is down there exploring when all of a sudden he comes across a VW bug in the middle of the ocean... Davy Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted December 24, 2003 Share Posted December 24, 2003 welll........the wind has very little effect on the ship, if at all. Better check with the deck pukes on that one. A carrier has significant sail area, more than any sail powered vessel. A big issue when you want to turn or moor one. Quote Link to comment Share on other sites More sharing options...
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