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Re: Go on, tell us Steve.........

Posted by Steve Hinton on Thu Mar 07, 2002 01:46:50 AM

In reply top Go on, tell us Steve......... posted by Tony on Wed Mar 06, 2002 10:12:30 AM

When we started the rebuild about 8 yrs ago, we intended to put it back as an origional PR 19. As we moved along with the process we were alarmed at the cost of the prop and engine overhaul. A stock MK 19 engine and prop will cost as much as 4 complete Shack engines and props. We had a limited budget and after considering the options we decided the Shack engine would be worth a try. It is a very attractive combination with some interesting benefits as well as some disadvantages. The MK 65 Griffon , stock for the 19, is rated at 2050 HP. The Mk 58 Shack engine is wet rated at 2435 HP. On take off in a MK 14 Spit (I am sure the 19 is in the same ball park) the rudder can't handle the full HP, too much torque. Contra rotaters do not produce torque. More HP on take off with no torque should give the Spit 8000 ft rate of climb. This is good. On the down side of this is the fact that the more blade area you have the more tail area required. Years ago Spitfires, Seafires and a red P-51 I had experience with flew with contra props. You can read the reports and see the growth of the tail area. This is a concern but not a safety issue. The MK 19 has an enlarged tail and has a high back fuselage which will also help provide more stability. My guess is it will be adequet until high speed, over 450, which is acceptable. The Mk 58 is 250# lighter because it is a single stage engine but with the aluminum contra props the installation is 200# heavier. This requires more lead in the tail, but still within limits. Some contra WW 2 Spitfires flew with 150# of lead in the vertical and aft battery mount. So this is a trade off. The Shack engine does not have an aftercooler like the stock MK 65 engine which means that we can use the extra radiator capacity for main system cooling. This is good. The MK 57/58 Shack engine has a great history and has overhaul life greater than the MK 65. This is good. If an engine failure occures with a loss of oil the contra props will go flat and the drag produced from the 2 props causes an extremely bad glide. I know this first hand. This is bad. We put an electric prop feathering system so the props can be controlled or feathered if needed during an emergengy. This is good. The aircraft is a great looking machine and the contra props make it look that much more interesting. The fact is we can try this combination and if it is not desireable we can put it back to a stock configuration. There have been no changes to the airframe that will keep it from being a stock MK 19. We are 98% finished with the systewms and airframe. We are fitting the spinner now and should be running the engine next week. We plan on painting it the PR Blue scheme with invasion stripes. We have no intention of racing it. I don't think it will be that fast, although years ago it might have been attractive. Slick wings, a boil off cooling system and I'll bet it could be a 460+ MPH Reno racer. Or, up until 2 years ago it could have had a good chance to take away the climb record for a prop aircraft. The Bearcat held the record, from a stop to 3000 meters in 83 seconds. The Spit, on paper can do it in 80 seconds. Now the record is held by a homebuilt machine called Raven at 65 seconds. Oh well. For our Chino air show this May 18 we hope to have several Brit machines flying including a Spit MK 9, 14 and 19. We should have pictures as we go www.planesoffame.org
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: 3 squadrons of those in 1940, and the Battle of Britain wo
: uld have been over in a fortnight.....
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: What a lovely looking beast
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: Tony

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