erich weaver
Well Known Member
Link to the article on Avweb
https://www.avweb.com/aviation-news/superior-settles-one-xp-400-lawsuit/
https://www.avweb.com/aviation-news/superior-settles-one-xp-400-lawsuit/
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Superior Settles XP-400 Lawsuit
- Thread starter erich weaver
- Start date
gmcjetpilot
Well Known Member
Why are things expensive in aviation? I feel bad for the loss of the two men and to their family. However flying has risks. XP400 is a hot rod engine. I would not put it in a daily flyer.
Just my opinion I am not a fan of hot rod aircraft engines, stroked, higher compression for general aviation, even experimental. The reason certified (config) Lycs and Continentals are reliable is because they are conservatively designed and operate bellow limits. 320 = 160HP max. 360 parallel valve =170HP - 180HP; 360 angle valve = 200 HP. I know custom displacements not made by Lyc, 340's, 390's and 400's are popular. It is up to the individual. I hot rodded a lot of car engines in the day.... but when one goes Boom you pull over to the side of the road.
Now with Elec Ignition and free flow headers even on stock Lycs there is more stress. I am willing to take that risk and more practical now CHT/EGT monitoring of every cylinder is so common. (I flew GA planes with no EGT or CHT gauge for years).
Just my opinion I am not a fan of hot rod aircraft engines, stroked, higher compression for general aviation, even experimental. The reason certified (config) Lycs and Continentals are reliable is because they are conservatively designed and operate bellow limits. 320 = 160HP max. 360 parallel valve =170HP - 180HP; 360 angle valve = 200 HP. I know custom displacements not made by Lyc, 340's, 390's and 400's are popular. It is up to the individual. I hot rodded a lot of car engines in the day.... but when one goes Boom you pull over to the side of the road.
Now with Elec Ignition and free flow headers even on stock Lycs there is more stress. I am willing to take that risk and more practical now CHT/EGT monitoring of every cylinder is so common. (I flew GA planes with no EGT or CHT gauge for years).
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Aviaman
Well Known Member
I agree-I’m not a fan of hot rod aviation engines. The original O-320s were only 150hp ——>less stress. In aviation reliability is the number one concern.
That being said, I have a another rant. GA has been crippled for many decades by over regulation and lawsuits. There is a vicious circle at work. Over regulation and lawsuits make it too expensive and risky for mfgrs. to adopt new technology. And even PMA parts become insanely expensive, driving up costs. Liability premiums for manufacturers drives some out of business, lessening the competition and choice. That makes costs even higher causing fewer sales, a downward spiral.
What seem sensible safety regulations in the short term, become a blockade to longer term technical advancement. That’s why our current Lycoming and Continental engines are still 1940s technology. Two things are needed to revive GA: Serious tort reform, and a regulatory environment where proven technology can be adopted for GA. That regulatory environment would include substantive voting power on FAA/DOT rule making by stakeholders. Those stakeholders could be airlines, manufacturers, general aviation representatives (AOPA, EAA), and the FAA itself. Perhaps such an arrangement would break the stranglehold of DOT/FAA. Just an idea, but not a new one.
That being said, I have a another rant. GA has been crippled for many decades by over regulation and lawsuits. There is a vicious circle at work. Over regulation and lawsuits make it too expensive and risky for mfgrs. to adopt new technology. And even PMA parts become insanely expensive, driving up costs. Liability premiums for manufacturers drives some out of business, lessening the competition and choice. That makes costs even higher causing fewer sales, a downward spiral.
What seem sensible safety regulations in the short term, become a blockade to longer term technical advancement. That’s why our current Lycoming and Continental engines are still 1940s technology. Two things are needed to revive GA: Serious tort reform, and a regulatory environment where proven technology can be adopted for GA. That regulatory environment would include substantive voting power on FAA/DOT rule making by stakeholders. Those stakeholders could be airlines, manufacturers, general aviation representatives (AOPA, EAA), and the FAA itself. Perhaps such an arrangement would break the stranglehold of DOT/FAA. Just an idea, but not a new one.
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IO-390/ 580s are certified and produced by Lycoming. Have good reliability. Certain aftermarket 340 and 375 PV engines seem to be reliable as well.
Electronic ignition won't add any stress if the timing map is properly developed. Spark should only be advanced when MAP is lower or when mixture is leaner. Peak cylinder pressures are not affected in this case. Too much advance may indeed increase stress and even induce detonation or pre-ignition which hugely increases stress.
Since many Lycoming engines are operated in the training environment at low altitude and near full power and still go to or past 2000 hours, adding a tuned exhaust to boost power at altitude in cruise adds no significant stress compared to low level, high power operation with a stock engine.
Most of the problems with cranks have been due to design, process control or metallurgical defects. Properly designed and built cranks almost never have issues and there are pretty huge safety margins present in these designs as evidenced by Reno race versions outputting well over double the stock rated hp and not blowing up.
Stretching a 3 main bearing, 360 inch design to 400 inches without careful consideration of journal size and fillet radaii and then not doing a LOT of dyno running to validate durability is asking for trouble. I've said it before, FEA is a design tool and is no substitute for an actual beating on the dyno for the full TBO period. I've seen some other aviation products designed using FEA which cracked or broke too. I feel some engineers today think that it can take the place of actual testing. Not IMO.
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