"I actually hope Apple loses in court, so they're forced to add true anti-rogue-signed-firmware security to future phones to keep up the fight (thus making it actually technically impossible to comply). "
If that happened, you can guarantee that Apple would be hauled before secret courts under homeland security laws and given secret orders that they'd have to comply with to backdoor for the govt.
Right now this is all in the open. Apple appear to be trying to ensure it stays there instead of heading into the USA's "national security" blackhole of unconstitutional, unappealable court orders.
HOW is it possible to do this? If a device is locked then it should need to be unlocked before an OS update can be applied.
This is a massive security backdoor all by itself, govt or no govt.
If you can update the OS this way then you can also image the device to external storage and then beat on that. The first rule of data recovery is "NEVER EVER WORK DIRECTLY ON THE DEVICE IN QUESTION"
"Depending on the software you write, and what you use it for... $5k for a development tool isn't that crazy stupid."
I work in a space lab. Spending this kind of money is easily justified on the basis that projects are either long-lived (20+ years) and/or software updates are often difficult (stuff that goes in a spacecraft is hard to do field calls on), so making sure stuff is well written in the first instance saves more than that in the long term.
Perhaps PVS should offer their services to Toyota.
"The majority of issues I've had with my vehicles over the last decade have been electrical and NOT mechanical,"
What frequency are they occuring at?
In the 1970s you expected to service your car every 2500 miles (oil and points) or it would die quickly. These days oilchanges are every 9000 miles and more complex maintenance is every 18,000 miles or at longer intervals (the 18,000 mile service is primarily filters, anything to do with timing, etc is every 36,000 miles)
Electronic controls have vastly reduced the complexity (and hence unreliability) of mechanical systems as well as eliminating many of the wear points which previously existed (points wear affecting timing and overall efficiency being the standout one).
Try running a 1970s or 80s-era car for those kinds of milages between servicing and it would leave you stranded on the side of the road.
The electrical "failures" I've had in my 2003-model car over 150,000 miles and 12 years are: 1: Burned out bulbs. 2: A bad earth causing the engine to hunt in power. This was traced to water-induced corrosion in a single plug. 3: Worn out coilpacks. 4: Worn out sparkplugs (iridium plugs lasting 70,000 miles) 5: A broken radio antenna. 6: worn out battery. 7: washer pumps failed (due to crud in the bottle blocking the pumps)
Mechanically it's gone through several sets of brake pads, the driver's window failed due to the clips holding the glass in place snapping, the driver's doorhandle mechanism died and I've recently replaced most of the suspension (shocks and rubber components) due to simple old age (125,000 miles)
The problems in my 1982 car over the same milage were 5 times higher than this (mostly mechanical) and the 1972 car I had before that was a regular workshop visitor from the day I got it. If you want to call that "vastly more electrical problems than mechanical" then that's your call, but I'd argue that 2, 5 and 7 were mechanically caused, that for #3 I'd have replaced the Kettring ignition coil, points, rubbing block and distributor cap in the 1982 and 72 cars several times over in the same period For #4 the same thing in spades, same on #6 (I averaged 2-3 years per battery at best on the old cars), #5 was vandalism and for #7 pumps died on both the older cars thanks to water leaking into the motors and causing them to seize. All that was needed this time was cleaning the impellers out.
Perhaps you drive a Lada or an american car, but most modern vehicles are extremely reliable. What failures of the electricals there are, are generally down to abuse, poor assembly or occur at much less frequent intervals than the servicing and failure intervals of the mechanical parts they replaced.
"Theoretically, with enough fine control over the valves and a good computer to control it, you could do away with the throttle altogether and use the valve duration, lift, and timing as the throttle."
"Through variable Camshaft Gears modern engines already control the in- and outlet timing for maximum efficiency today"
When you show me a purely mechanical cam which can dynamically double pop the inlet valve or do late opening/early closure under lightly loaded conditions like Fiat's Multiair cam augmenttation system does in order to eliminate the throttle system, I'll agree with you.
Otto engines are only efficient at max load/wide open throttle. At all other loads they're rotten and most of that comes back to the fact that a throttle is needed.
Conventional variable cams can only adjust opening duration over specific RPM and/or load ranges. All valvetrain cam operation is a compromise in a automotive engine, given the near infinite range of power and rpm demands placed upon it.
On the other hand if you can run one at fixed speed and power load, you don't need any of the complexity (and weight) associated with a variable valvetrain and can tune for best power output. This is the guiding principle behind a series hybrid - even then, being able to eliminate the mass of the cam system is a winner for automotive use.
That's the whole point of solenoid systems. If you're using a solenoid to open the valve and fighting against spring-closure then it's not worth moving away from camshafts.
A workable solenoid system has to be able to open _and close_ the valves.
This is what Fiat have achieved in their multiair systems, using cam-actuated pneumatics to open/close the inlet valves (no return springs. Pneumatics move the valve in both directions) where the activation is electronically augmented to achieve late opening, early closure, multiple openings per stroke (or no opening at all) in order to eliminate the throttle.
Technically there's no reason why they need a camshaft at this point. Whilst Multiair still uses it to directly operate the exhaust valves (there are few advantages in playing with exhaust valve opening lift/duration/etc and has a fallback position of "limp home" operation if the electronics fail, the electronics has proven extremely reliable and the fact that the timing is already well under control is seen in the electronic enhancement of the pnuematics.
Even if solenoids can't _directly_ drive valves at the moment, they can be used to control pneumatic openers/closers at sufficient speed and accuracy that the cam is already obsolete. A large part of why you don't see camless Fiats (yet) is manufacturer conservatism. Taking them out is a big step and consumers may resist.
I never said turbines weren't gas hogs. That's a given. The advantages of using turbines (turboshafts) over other powerplants (compactness, lightness and much higher power output per package size) are what tends to tip the balance.
The links about the diesels are interesting, but the primary driver of using the turboshaft in the first instance was size and mass along with standardisation of fuel sources.
As you say the M1A1 is already big and heavy. At the time it was designed (mid 1970s) suitable (usa-made) diesels simply weren't available without making the thing even bigger and heavier than it already is - which would have made it unable to use european bridges or railways and whilst the military has historically never worried overly about maintenance ratios, piston-based tank engines have historically been the least reliable part of the entire platform so there was already a mindset against them. (In aviation and power generation, turboshafts have less than 1/10 the maintenance requirements of piston engines. This is the kind of data which would have weighed in favour of designers at the time)
WRT fuel consumption: It takes about the same amount of fuel to start a cold-war era diesel tank. Bear in mind that the M1A1 is a product of the Cold War - a 40-year old design - whilst the examples you've quoted are all 21st century entries, with that much more development behind them.
The new GD diesel makes use of advances in both materials technology and diesel systems which have come along since the M1A1 design was finalised and weren't even available even 15 years ago. It's no real surprise that it's smaller and more powerful than its predecessors. 40 years of engineering development makes a big difference and fuel logistics weren't a major consideration for cold war deployments in any case - they've only been important since the Gulf War showed them as an issue.
The same reason the GD engine has advantages in the M1A1 is the same reason that aeromotive diesels are becoming more popular over Turboprops in smaller aircraft: 40+ years of R&D have resulted in many of piston engine disadvantages being solved.
Try not to compare apples (1970s engine technology) with orange juice (2010s engine technology) without at least reflecting on the reasons the older technology was selected at the time.
As a final point: Turboshafts are widely used in civil power stations, even coal ones - even though they're less efficient than piston engines, BUT... their extremely hot exhaust is perfect for running boilers and steam turbines, which scavenges a large proportion of the "wasted" energy. This results in Combined Cycle Gas Turbine(CCGT) civil electrical plants having much greater overall efficiency than pure steam plants.
Piston-powered generators have much lower exhaust temperatures(to avoid damaging the engines) and as such don't provide enough heat energy to run efficient steam turbine systems, so operators seldom bother. This heat energy issue is the same problem that conventional civil nuclear power plants have, but nuclear fuel is much cheaper than coal, so the operators live with the inefficiency. Molten salt nuclear designs run much hotter and would improve operational thermodynamic efficiency from low 20%s to mid 30%s (and not have the issue of hot pressurised water contaminated with radioactive particles wanting to flash to steam at any opportunity - prventing this event is the primary cost driver of current nuclear power technology.)
"Valve are heavy relative to the accelerations needed by the motion profiles"
You've never pulled an IC engine apart. Automotive poppet valves are built as light as possible (sometimes with hollow stems or sodium filled stems). In general they have just enough mass to conduct heat away from the hottest part of the engine and prevent misfiring.
The stiffness comes from the return springs and they usually have 2-3 times the mass of the valves themselves (remember, unsprung mass should be as low as possible in a suspension system and a poppet valve is a form of suspension system)
"Gasoline was faster, more convenient , could carry more and carry it further than what it eventually replaced. "
Electric cars were around first and there were more of them (as were steam cars). Gasoline came later and was regarded as far inferior - the advantage was that you could carry much more fuel (range) with you on a longer trip and buy 2 gallon bottles of gasoline at most drugstores(*), whereas electricity was limited in availability.
" More worrisome are the control electronics and wiring."
Only if you have an american car. Even Italian/british/french cars have reliable wiring/electronics these days (hint: Grease-filled connectors can't get filled with water and then corrode. Don't use silicon grease)
Refining the algorithms is the issue. Once suitable long-life solenoids are in use and the concept is proven, all makers will pick this up - mechanical complexity costs more and weighs more than computing algorithms.
Which in turn means that battery-only vehicles have limited range compared to a car with 50 kg of fuel in it unless you're willing to crank up the mass, which in turn comes with performance and wear penalties (a 5 ton car is going to have to have tougher wheel bearings, will have higher rolling friction and chew up tyres faster). It's all about compromise. 90%+ of car travel worldwide involves round trips of less than 30 miles but people want the ability to be able to go 300 without special preparation.
There have been (and are) designs which move the rocker pivot points dynamically.
However - "mechanical complexity" rears its head. The more mechanically complex a device is, the harder it is to maintain and the easier it is to break - particularly in automotive engines when a lot of "mechanics" should be wearing striped aprons, not blue overalls.
"That being said, the camless designs have their own challenges, namely soft valve seat landings due to a nearly perfect square-wave lift profile."
I suspect that problem (mostly caused by the need for incredibly stiff springs) is vastly overstated when the valve doesn't have a camshaft pushing it.
"The biggest change that can be made to the valve system is to move away from springs and to a manual close system"
This has been around almost forever (desmodronics was developed back in 1896) but adds a _lot_ of mechanical complexity when done with cams - there's a reason that only Ducati have stuck with it.
Electronics tends to be far more reliable than mechanical parts and distributors wear out. This has a lot to do with why manufacturers quickly moved to coilpacks after doing away with the traditional "points" in a kettering coil ignition system - firstly to optical or hall-effect triggers replacing the points in a TAI setup and then to flywheel-mounted sensors - the toothed wheels now in use give extremely precise, repeatable timing to far better tolerances than any mechanical system will allow.
For what it's worth - a poppet valve without springs is very light and trivial to move. Many are hollow-stemmed. The "springs" are big in order to push back _hard_ against the camshaft follower and ensure there is no "lash" and extremely stiff + usually composed of 2 or more springs on each valve to avoid mechanical resonances and avoid valve bounce at high speeds. A solenoid is more than fast+strong enough to open one even at 6000rpm (50 operations/second). A suitable dual-acting solenoid would be able to push and pull the valve.
Moving to scissor or other valve types is impractical. Poppet valves are effectively self-sealing under pressure and the inside of a cylinder is a hostile environment. Rotating/sliding valves have been tried in the past and they _ALL_ suffered badly from pressure leakage issues.
"M1A1 battle tanks are well-known for being gas hogs. The advantage they have is their turbines will run on all kinds of different fuels"
The advantage for M1A1 is the same for putting turbines on aircraft wings. Power to weight (and size) ratio is more important than absolute unit efficiency in this kind of case.
You can get a lot of power in a small space when you use a turbine. Conventional piston engines take up a large amount of space in a tank body. The M1A1 would end up being substantially bigger and heavier (or a LOT slower) if it was constrained to using conventional traditional diesel engines - plus those conventional engines are high maintenance + fragile due to mechanical complexity and operating close to material design limits.
By way of comparison: It's been estimated that the original 747-100 would have needed ~10 piston engines on each wing to match the output of the jet engines and make up for the extra weight of those piston engines (or to put it another way, imagine the Spruce Goose only needing 4 turbine engines)
"always running in its narrow efficient RPM range"
Turbines are only efficient when operating in "the narrow RPM range" and at full load.
At any other load they're spectacularly inefficient, much more so than piston engines. This is the primary reason why GE's turbine-electric locomotives were fitted with auxilliary diesel generators for non-full-load operation (although noise considerations in populated areas came into it too).
They are also amazingly easy to destroy at startup (particularly hot start), which is why pilots need a turbine rating _in addition_ to the aircraft type rating in order to be allowed to fire the things up.
Finally, you can't just fire up a turbine and apply load immediately. Until it hits thermal equilibrium doing so will probably destroy it too. They may be able to eat almost any kind of fuel but they're very fragile devices - and the kinds of shock loads encountered in a car won't help. Centrifigual turbines are tougher, but also larger and less efficient.
"and they'll be instantly sued by toyota/lexus because that's how their atkins cycle engines works"
Miller cycle was patented in 1957, so is long-expired. It wasn't used in cars because of the lower power-to-weight ratio.
Toyota had a gas turbine in the 80s and yes they did scrap the engine - not for reasons you think. (Poor fuel efficiency at anything other than 90+% load, high exhaust temperatures and the ease with which an inexperienced user can wreck one at startup were the killers) - HOWEVER the electronic control system and gearbox associated with the GTV research are the core of Toyota's hybrid system.
In particular: gtvs were not sluggish, and toyota's ones were quieter than piston engined vehicles. RPM changes are slow but increased torque is instantly available when you put your foot down. The multiple input CVT that was developed to allow turbine RPM to stay constant (and to allow multiple turbines) turned out to be the jewel in the R&D crown. The GTV project turned into a GTV hybrid and then dropped the turbine.
Slashdot Mirror
"I actually hope Apple loses in court, so they're forced to add true anti-rogue-signed-firmware security to future phones to keep up the fight (thus making it actually technically impossible to comply). "
If that happened, you can guarantee that Apple would be hauled before secret courts under homeland security laws and given secret orders that they'd have to comply with to backdoor for the govt.
Right now this is all in the open. Apple appear to be trying to ensure it stays there instead of heading into the USA's "national security" blackhole of unconstitutional, unappealable court orders.
HOW is it possible to do this? If a device is locked then it should need to be unlocked before an OS update can be applied.
This is a massive security backdoor all by itself, govt or no govt.
If you can update the OS this way then you can also image the device to external storage and then beat on that. The first rule of data recovery is "NEVER EVER WORK DIRECTLY ON THE DEVICE IN QUESTION"
"Depending on the software you write, and what you use it for ... $5k for a development tool isn't that crazy stupid."
I work in a space lab. Spending this kind of money is easily justified on the basis that projects are either long-lived (20+ years) and/or software updates are often difficult (stuff that goes in a spacecraft is hard to do field calls on), so making sure stuff is well written in the first instance saves more than that in the long term.
Perhaps PVS should offer their services to Toyota.
"The majority of issues I've had with my vehicles over the last decade have been electrical and NOT mechanical,"
What frequency are they occuring at?
In the 1970s you expected to service your car every 2500 miles (oil and points) or it would die quickly. These days oilchanges are every 9000 miles and more complex maintenance is every 18,000 miles or at longer intervals (the 18,000 mile service is primarily filters, anything to do with timing, etc is every 36,000 miles)
Electronic controls have vastly reduced the complexity (and hence unreliability) of mechanical systems as well as eliminating many of the wear points which previously existed (points wear affecting timing and overall efficiency being the standout one).
Try running a 1970s or 80s-era car for those kinds of milages between servicing and it would leave you stranded on the side of the road.
The electrical "failures" I've had in my 2003-model car over 150,000 miles and 12 years are: 1: Burned out bulbs. 2: A bad earth causing the engine to hunt in power. This was traced to water-induced corrosion in a single plug. 3: Worn out coilpacks. 4: Worn out sparkplugs (iridium plugs lasting 70,000 miles) 5: A broken radio antenna. 6: worn out battery. 7: washer pumps failed (due to crud in the bottle blocking the pumps)
Mechanically it's gone through several sets of brake pads, the driver's window failed due to the clips holding the glass in place snapping, the driver's doorhandle mechanism died and I've recently replaced most of the suspension (shocks and rubber components) due to simple old age (125,000 miles)
The problems in my 1982 car over the same milage were 5 times higher than this (mostly mechanical) and the 1972 car I had before that was a regular workshop visitor from the day I got it. If you want to call that "vastly more electrical problems than mechanical" then that's your call, but I'd argue that 2, 5 and 7 were mechanically caused, that for #3 I'd have replaced the Kettring ignition coil, points, rubbing block and distributor cap in the 1982 and 72 cars several times over in the same period For #4 the same thing in spades, same on #6 (I averaged 2-3 years per battery at best on the old cars), #5 was vandalism and for #7 pumps died on both the older cars thanks to water leaking into the motors and causing them to seize. All that was needed this time was cleaning the impellers out.
Perhaps you drive a Lada or an american car, but most modern vehicles are extremely reliable. What failures of the electricals there are, are generally down to abuse, poor assembly or occur at much less frequent intervals than the servicing and failure intervals of the mechanical parts they replaced.
"Theoretically, with enough fine control over the valves and a good computer to control it, you could do away with the throttle altogether and use the valve duration, lift, and timing as the throttle."
It's not a theory. Fiat have already done it.
"Through variable Camshaft Gears modern engines already control the in- and outlet timing for maximum efficiency today"
When you show me a purely mechanical cam which can dynamically double pop the inlet valve or do late opening/early closure under lightly loaded conditions like Fiat's Multiair cam augmenttation system does in order to eliminate the throttle system, I'll agree with you.
Otto engines are only efficient at max load/wide open throttle. At all other loads they're rotten and most of that comes back to the fact that a throttle is needed.
Conventional variable cams can only adjust opening duration over specific RPM and/or load ranges. All valvetrain cam operation is a compromise in a automotive engine, given the near infinite range of power and rpm demands placed upon it.
On the other hand if you can run one at fixed speed and power load, you don't need any of the complexity (and weight) associated with a variable valvetrain and can tune for best power output. This is the guiding principle behind a series hybrid - even then, being able to eliminate the mass of the cam system is a winner for automotive use.
That's the whole point of solenoid systems. If you're using a solenoid to open the valve and fighting against spring-closure then it's not worth moving away from camshafts.
A workable solenoid system has to be able to open _and close_ the valves.
This is what Fiat have achieved in their multiair systems, using cam-actuated pneumatics to open/close the inlet valves (no return springs. Pneumatics move the valve in both directions) where the activation is electronically augmented to achieve late opening, early closure, multiple openings per stroke (or no opening at all) in order to eliminate the throttle.
Technically there's no reason why they need a camshaft at this point. Whilst Multiair still uses it to directly operate the exhaust valves (there are few advantages in playing with exhaust valve opening lift/duration/etc and has a fallback position of "limp home" operation if the electronics fail, the electronics has proven extremely reliable and the fact that the timing is already well under control is seen in the electronic enhancement of the pnuematics.
Even if solenoids can't _directly_ drive valves at the moment, they can be used to control pneumatic openers/closers at sufficient speed and accuracy that the cam is already obsolete. A large part of why you don't see camless Fiats (yet) is manufacturer conservatism. Taking them out is a big step and consumers may resist.
I never said turbines weren't gas hogs. That's a given. The advantages of using turbines (turboshafts) over other powerplants (compactness, lightness and much higher power output per package size) are what tends to tip the balance.
The links about the diesels are interesting, but the primary driver of using the turboshaft in the first instance was size and mass along with standardisation of fuel sources.
As you say the M1A1 is already big and heavy. At the time it was designed (mid 1970s) suitable (usa-made) diesels simply weren't available without making the thing even bigger and heavier than it already is - which would have made it unable to use european bridges or railways and whilst the military has historically never worried overly about maintenance ratios, piston-based tank engines have historically been the least reliable part of the entire platform so there was already a mindset against them. (In aviation and power generation, turboshafts have less than 1/10 the maintenance requirements of piston engines. This is the kind of data which would have weighed in favour of designers at the time)
WRT fuel consumption: It takes about the same amount of fuel to start a cold-war era diesel tank. Bear in mind that the M1A1 is a product of the Cold War - a 40-year old design - whilst the examples you've quoted are all 21st century entries, with that much more development behind them.
The new GD diesel makes use of advances in both materials technology and diesel systems which have come along since the M1A1 design was finalised and weren't even available even 15 years ago. It's no real surprise that it's smaller and more powerful than its predecessors. 40 years of engineering development makes a big difference and fuel logistics weren't a major consideration for cold war deployments in any case - they've only been important since the Gulf War showed them as an issue.
The same reason the GD engine has advantages in the M1A1 is the same reason that aeromotive diesels are becoming more popular over Turboprops in smaller aircraft: 40+ years of R&D have resulted in many of piston engine disadvantages being solved.
Try not to compare apples (1970s engine technology) with orange juice (2010s engine technology) without at least reflecting on the reasons the older technology was selected at the time.
As a final point: Turboshafts are widely used in civil power stations, even coal ones - even though they're less efficient than piston engines, BUT... their extremely hot exhaust is perfect for running boilers and steam turbines, which scavenges a large proportion of the "wasted" energy. This results in Combined Cycle Gas Turbine(CCGT) civil electrical plants having much greater overall efficiency than pure steam plants.
Piston-powered generators have much lower exhaust temperatures(to avoid damaging the engines) and as such don't provide enough heat energy to run efficient steam turbine systems, so operators seldom bother. This heat energy issue is the same problem that conventional civil nuclear power plants have, but nuclear fuel is much cheaper than coal, so the operators live with the inefficiency. Molten salt nuclear designs run much hotter and would improve operational thermodynamic efficiency from low 20%s to mid 30%s (and not have the issue of hot pressurised water contaminated with radioactive particles wanting to flash to steam at any opportunity - prventing this event is the primary cost driver of current nuclear power technology.)
"Disk brakes stop better, last longer, and are a simpler setup yet there are still vehicles that have drum brakes today."
Drum brakes are cheaper, less prone to contamination and keep working when wet.
1: Yes, the energy requirements are high - but you're already disspiating this in a mechanical system and then some.
2: You assume 12V actuators. There's nothing preventing higher voltages being used.
3: Not as good a radio transmitter as an old fashioned distributor and spark ignition system, and you can shield it.
"A mechanical engineer pointed out to me when I was a teenager that the majority of engine "problems" where electrical/electronic and not mechanical."
You must have been a teenager a long time ago. That hasn't been the case in over 40 years.
"Valve are heavy relative to the accelerations needed by the motion profiles"
You've never pulled an IC engine apart. Automotive poppet valves are built as light as possible (sometimes with hollow stems or sodium filled stems). In general they have just enough mass to conduct heat away from the hottest part of the engine and prevent misfiring.
The stiffness comes from the return springs and they usually have 2-3 times the mass of the valves themselves (remember, unsprung mass should be as low as possible in a suspension system and a poppet valve is a form of suspension system)
"Gasoline was faster, more convenient , could carry more and carry it further than what it eventually replaced. "
Electric cars were around first and there were more of them (as were steam cars). Gasoline came later and was regarded as far inferior - the advantage was that you could carry much more fuel (range) with you on a longer trip and buy 2 gallon bottles of gasoline at most drugstores(*), whereas electricity was limited in availability.
(*) It was sold as cleaning fluid.
" More worrisome are the control electronics and wiring."
Only if you have an american car. Even Italian/british/french cars have reliable wiring/electronics these days (hint: Grease-filled connectors can't get filled with water and then corrode. Don't use silicon grease)
Refining the algorithms is the issue. Once suitable long-life solenoids are in use and the concept is proven, all makers will pick this up - mechanical complexity costs more and weighs more than computing algorithms.
The Wh/kg ratio of batteries is the issue.
Petrol/Diesel is around 10kWh (usable) per kg.
Batteries are hard pressed to hit 500Wh/kg
Which in turn means that battery-only vehicles have limited range compared to a car with 50 kg of fuel in it unless you're willing to crank up the mass, which in turn comes with performance and wear penalties (a 5 ton car is going to have to have tougher wheel bearings, will have higher rolling friction and chew up tyres faster). It's all about compromise. 90%+ of car travel worldwide involves round trips of less than 30 miles but people want the ability to be able to go 300 without special preparation.
"The trailing profile on a cam is there to slow down the valve as it closes"
See previous comments about the springs....
There have been (and are) designs which move the rocker pivot points dynamically.
However - "mechanical complexity" rears its head. The more mechanically complex a device is, the harder it is to maintain and the easier it is to break - particularly in automotive engines when a lot of "mechanics" should be wearing striped aprons, not blue overalls.
"That being said, the camless designs have their own challenges, namely soft valve seat landings due to a nearly perfect square-wave lift profile."
I suspect that problem (mostly caused by the need for incredibly stiff springs) is vastly overstated when the valve doesn't have a camshaft pushing it.
"The biggest change that can be made to the valve system is to move away from springs and to a manual close system"
This has been around almost forever (desmodronics was developed back in 1896) but adds a _lot_ of mechanical complexity when done with cams - there's a reason that only Ducati have stuck with it.
"What distributor? "
Exactly. One less mechanical component.
Electronics tends to be far more reliable than mechanical parts and distributors wear out. This has a lot to do with why manufacturers quickly moved to coilpacks after doing away with the traditional "points" in a kettering coil ignition system - firstly to optical or hall-effect triggers replacing the points in a TAI setup and then to flywheel-mounted sensors - the toothed wheels now in use give extremely precise, repeatable timing to far better tolerances than any mechanical system will allow.
For what it's worth - a poppet valve without springs is very light and trivial to move. Many are hollow-stemmed. The "springs" are big in order to push back _hard_ against the camshaft follower and ensure there is no "lash" and extremely stiff + usually composed of 2 or more springs on each valve to avoid mechanical resonances and avoid valve bounce at high speeds. A solenoid is more than fast+strong enough to open one even at 6000rpm (50 operations/second). A suitable dual-acting solenoid would be able to push and pull the valve.
Moving to scissor or other valve types is impractical. Poppet valves are effectively self-sealing under pressure and the inside of a cylinder is a hostile environment. Rotating/sliding valves have been tried in the past and they _ALL_ suffered badly from pressure leakage issues.
"M1A1 battle tanks are well-known for being gas hogs. The advantage they have is their turbines will run on all kinds of different fuels"
The advantage for M1A1 is the same for putting turbines on aircraft wings. Power to weight (and size) ratio is more important than absolute unit efficiency in this kind of case.
You can get a lot of power in a small space when you use a turbine. Conventional piston engines take up a large amount of space in a tank body. The M1A1 would end up being substantially bigger and heavier (or a LOT slower) if it was constrained to using conventional traditional diesel engines - plus those conventional engines are high maintenance + fragile due to mechanical complexity and operating close to material design limits.
By way of comparison: It's been estimated that the original 747-100 would have needed ~10 piston engines on each wing to match the output of the jet engines and make up for the extra weight of those piston engines (or to put it another way, imagine the Spruce Goose only needing 4 turbine engines)
"always running in its narrow efficient RPM range"
Turbines are only efficient when operating in "the narrow RPM range" and at full load.
At any other load they're spectacularly inefficient, much more so than piston engines. This is the primary reason why GE's turbine-electric locomotives were fitted with auxilliary diesel generators for non-full-load operation (although noise considerations in populated areas came into it too).
They are also amazingly easy to destroy at startup (particularly hot start), which is why pilots need a turbine rating _in addition_ to the aircraft type rating in order to be allowed to fire the things up.
Finally, you can't just fire up a turbine and apply load immediately. Until it hits thermal equilibrium doing so will probably destroy it too. They may be able to eat almost any kind of fuel but they're very fragile devices - and the kinds of shock loads encountered in a car won't help. Centrifigual turbines are tougher, but also larger and less efficient.
"and they'll be instantly sued by toyota/lexus because that's how their atkins cycle engines works"
Miller cycle was patented in 1957, so is long-expired. It wasn't used in cars because of the lower power-to-weight ratio.
Toyota had a gas turbine in the 80s and yes they did scrap the engine - not for reasons you think. (Poor fuel efficiency at anything other than 90+% load, high exhaust temperatures and the ease with which an inexperienced user can wreck one at startup were the killers) - HOWEVER the electronic control system and gearbox associated with the GTV research are the core of Toyota's hybrid system.
In particular: gtvs were not sluggish, and toyota's ones were quieter than piston engined vehicles. RPM changes are slow but increased torque is instantly available when you put your foot down. The multiple input CVT that was developed to allow turbine RPM to stay constant (and to allow multiple turbines) turned out to be the jewel in the R&D crown. The GTV project turned into a GTV hybrid and then dropped the turbine.
Or a compressed-air starter could be used.
It's what big rigs have.
Assuming gasoline you still need electrickery to make the sparky stuff that makes the fuel go woof.
Whether that's from a battery or generator driven by the crankshaft, it's still electricity.