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« ตอบ #26 เมื่อ: กรกฎาคม 15, 2005, 07:30:16 AM » |
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" Starting the engine could be a chore if the correct procedure was not followed. The early Hellcats were equipped with the "shotgun"-type starter that had sufficient power to turn the engine over only about three or four revolutions before it ran out of energy. If it took a pilot more than one shell to get started, he was considered a dud. Electric starters were installed after about 2,000 production Hellcats had been built. "
" I have a starter shot-shell for the engines used in the movie. It is approximately 8 guage and was loaded with FFFG black powder. My dad did destructive testing on radial engines, for Curtis-Wright, during WW II. The engine company went to great lengths to try to make sure a damaged engine would still bring our boys home. Dad said that by war's end, they could blow 3 cylenders off an engine as it was running under 'war-time full power'(throttle wide open, turbos cranked to max RPM) with a stick or 2 of dynamite(to simulate a 40 mm cannon hit)and run the remaining 15 cylenders with no oil pressure for 1/2 an hour before the engine would blow up! The engineers also once ran a 9 cylender engine for 3 hours with 4 cylenders blown off and the crankcase split under reduced power. When this engine finally failed, the resulting destruction was spetacular! My dad said the engine started to slow for the last two minutes of operation. As the military wanted to maintain 75% RPM until the engine failed, thats what they did. As the engine began its death throes, it began to labor, and slow down. To keep the RPMs at the desired level, the throttles and turbo boost were increased, until the last 15 seconds were under wide open throttle. Dad didn't think the turbo was supplying too much boost as the blast that originally crippled the engine caused a lot of damage. Anyways, the poor engine cranked out its last 15 seconds in a fury of fire - the remaining 5 cylenders were red hot, there was molten aluminum from the heads dripping on the floor of the engine house, the remains of the exhause manifold was a bright yellow-white heat at the exhaust ports, and molten bearing metal was being sprayed out of the broken crankcase. The 4 jugs that had been blown off the engine, took the pistons and rods with them, as they left the engine house - via the roof! The 2 engineers stayed with the engine until the last 30 seconds, leaving only after there was no more throttle advance! Several high speed movie cameras (top secret at the time), were then set in motion to watch the engine failure that was sure to come. When the engine finally blew, it was heard all over Patterson NJ, the site of the engine test site. Dad said that when it blew, he and the other engineer figured they had about 10 seconds after full throttle, until the engine blew. After 20 seconds, they were worried that the cameras would run out of film, and they started back to the engine house to try to reload the cameras. They got about 20 yards closer to the engine shed , about another 10 seconds later, when it blew, knocking them flat on their backs, spraying them with molten metal, along with 3 members of the military guards assigned to watching the cameras. About 20 other people were knocked flat, several seriously either burned or hit with debris. The engine explosion blew the brick engine house into rubble. The engine itself litterally blew itself to fragments, and the magnesium parts caught fire. There were red hot iron and steel parts lying all over the place, molten aluminum was sprayed for 20 yards (my dad had a nasty looking hole in his leg where a 1/4" drop of aluminum had burned its way thru his calf). One red hot cylender even landed on the roof of a nearby building and set it afire. Of the 4 cameras set up to watch the engine, one was destroyed. and the other 3 were severely damaged. 2 of them had run out of film before the engine blew, but 1 did not. The man who set it up had set it to record at a different frame per second rate, so it ran at a slower speed, than specified. It did manage to catch the blow up in all its gory glory, running out of film about 2 seconds after the engine failed. My dad said studying the film made him and all the other engineers on the project sit back and think after this one blew up. The engine exploded like a shrapnell grenade! Because of the wrong film speed, they didn't see all the details they wanted, but if the camera had been set properly, they would have had nothing at all to look at. Dad said at the last few seconds, the magnesium engine block actually started to burn with all the heat from the cylenders and superheated internal parts. The remaining cylenders all seperated from the block within 1 1,000 of a second, 2 1,000 of a second later, the red hot crank and main rod also left the now burning and desintergrating block, along with the 6 foot diameter 4 bladed test propellor out the back of the test shed (thru a 2 foot thick brick wall (the prop and part of the crankshaft went about 40 yards, stopping partially imbedded in wall. The remaining pieces had already been launched thru the roof (the weakest point) and the other walls. The record distance was part of one of the engine heads, that was found the next day by some local kids, about an 1/8th of a mile from the engine test shed. From the moment of failure to the end was less than 2 tenths of a second! Anyways, to get back to the original question, dad said that the shell starters did almost as much damage to the engines as the axis powers! apperrently there was not too much quality control in the shotshell manufacturing, as thay had to pull apart quite a few engines after shell starting, because the shell either left too much debris in the chamber after firing, (raw powder would enter the cylender, and cause damage) or the piston that took the detonation to start the engine, would suffer crown failure (a hole would be blown into the piston head or crown!). Andrew "
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