turboplanner

......opening submission by Raelene from Ayr a who said “YAAAAAAAH he’s a bull alright eh!”, which brought the house down, then......

....and RM said Bull is my best friend and Bulls have been my livelihood; I've never killed one, never insulted one, never had one chase me, and never hit a black one at night in the Landcruiser like everyone else; I just get Bullskins and with the utmost respect turn them into attractive items that all Bulls would be proud of.

RM then presented References from every Station in the Kidman Empire, except The Big Muddy, and that's the one the lawyers pounced on because................

22 minutes ago, danny_galaga said:

I have a bet with a workmate that in ten years you won't be able to buy a new ICE car. My main argument is that Australia has no bearing on what the rest of the world is manufacturing (gee, maybe canning all car manufacturing here wasnt so great an idea). 

Since we import most of our cars from the northern hemisphere that could well come true.

The problem for Australia is that unless a battery/range breakthrough occurs that would spell disaster for regional Australia.

.....that no one posted, so .......

8 hours ago, aro said:

There was a startup called Better Place trying to build a network of battery swap stations for EVs. It relied on standardized batteries accessible from under the car.

 

In order to access the battery switch station, Better Place customers would have to swipe their membership card. The remaining process was fully automated, similar to going through a car wash, so the driver never had to leave the car

 

The car owner wouldn't own the batteries, they just purchased the electricity. So all the problems with battery degradation etc. would be managed by Better Place across their whole inventory rather than being a risk to the car owner.

 

https://en.wikipedia.org/wiki/Better_Place_(company)

 

Hard to know whether its a better or worse idea than charging stations. Their biggest problem appears to have been no-one driving electric cars at that time.

The theory is good because it would allow banks of batteries to be charged at their charging time, and swapped into vehicles that pulled in for their trip interval time, so in theory you could drive from Melbourne to Brisbane without any range issues. To achieve it would require an Australian Standard battery pack, and that's where the problem comes, because EVs are in the embryo phase where massive design changes are being introduced for many reasons. In the manufacturing process you have the trial vehicles, first production vehicles, then continuous changes to fix issues, improve the product (called break points). it gets so complex that we used to have parts interpreters employed to find the correct replacement part for the particular break point vehicle. The State Registration Authorities now release their data to manufacturers, so all the parts counter person has to do is get your registration number and the VIN is captured, break point identified, correct part supplied. This would be one of the sticking points to a battery standard at this early stage.

2 hours ago, onetrack said:

There's simply no need to take 2 hrs to do a battery swap. Proper designing would see a slide-in battery cradle and a swap done in less time than it takes to put 80 litres of diesel into your Landcruiser.

 

And the changeover cost for a Nissan Leaf battery might be $9500 from the Nissan dealer at present - but a little competition will soon see that drop to around $2000-3000.

 

I've currently got a Ford Ranger diesel in the Ford dealer getting fixed (it wouldn't start). The dealer advised the injectors would probably need replacing, and the high pressure pump for the common rail could also need replacement.

They quoted me $800 for each genuine Ford injector, and $3000 for a new genuine Ford HP pump. Yet, I can obtain genuine Bosch injectors for under $400 each, and a genuine Bosch HP pump for $975 - fitted.

And Bosch make the injectors and pumps for Ford. The rorting is from when the components arrive in a Ford-branded box.

I haven't looked at the battery modules in a Nissan Leaf, but it's a good example because battery replacement cost is readily available.

The latest cost I've seen is $9,990.00 for a battery pack about every 10 years plus changover at $510 = $10.500.00 to factor in to total cost of life. I would guess that allows for about 4 hours labour. I understand what you are saying about a battery rack, but EVs have a lot more battery space than a single rack would allow, and my guess is that a lot more is going on if it takes 4 hours to replace them. I think you can forget about the analogy with the gas bottle for this reason, let alone the financial consideration of "your" $9,990 worth of batteries. As you say, there wold inevitably be an aftermarket, but the life cycle pattern and management will be different to ICE.

If you transfer the today's battery scenario over to an aircraft, and you want to fly cross country, you wold be looking at a pattern of doing your trip, then staying overnight for a full charge, then returning.

I quoted 20 hours for a full charge, here are some accurate figures for the Tesla S

3.7 kW charge:  27 hours   (This is the typical home wall pack for top up charging overnight)

7 kW charge: 15 hours

2 kW charge: 4 hours

For any serious range use the cost to buy and wire a home unit is around $7,500.00 and there is a limit on the number of these chargers in a street. If everyone wanted fast chargers the entire street system back to the transformer has to be upgraded, and the end result we found out during the last Federal election was that if Labor had achieved a 50% market share of EV, we would have had to build around double our current number of power stations.

3 minutes ago, octave said:

 

All vehicles rack up CO2 being built no matter what they are powered by. In addition petrol and diesel fuel racks up CO2 in its  extraction, shipping overseas, refining and delivery to service stations.  We know the negative effects of burning fuel not just CO2 but other pollutants which are unhealthy.

Yes Octave, I was talking about CO2 emissions over and above the ICE materials and build; it was direct one on one comparisons within the industry which started the doubt about the EV crusade.

4 minutes ago, octave said:

This is not right.  My sons Tesla has a 75KWh battery. At his home he has a 7KWh charger, I will leave you to do the maths.   Tesla superchargers are 120Kw and I believe there are even 250kw again you can do the maths.   We travel around NZ in the Tesla with no problems. Est range for this vehicle is 657km although that is in ideal conditions.

I certainly quoted from memory, so I'll check back and let you know, because the one I quoted wasn't the only one which took an impractical amount of time from flat to full charge.

16 minutes ago, octave said:

Certainly other countries are moving forward with technology. 

 

The City with 16,000 Electric Buses & 22,000 Electric Taxis | 100% Independent, 100% Electric

Moving forward? you certainly aren't giving us much technical information Octave. Plenty of hyperbole though.

There's a new term which has come into use by responsible vehicle manufacturers - "Zero Tailpipe CO2"

As we saw during the last Federal election campaign, when the CO2 for exotic materials and coal fired Power Stations was included in the EV equation, the EVand its Satellite CO2 emissions were around 20% greater than ICE, so a pointless exercise even thinking about EV.

Hence, 16,000 EV Buses may emit no "Tailpipe: CO2, but they've racked up CO2 emissions being built and will rack up more at battery changeover every ten years. Then you start to look at how the power is generated to recharge these buses, given that the daily charge will be huge. If Chenxing is pulling from a nuclear Power Station then the CO2 emissions are those parasite CO2 emissions mentioned. On the other end of the scale if their power is coal-fired, they've gone backwards.

1 hour ago, octave said:

 

Really? If you charge an EV from a standard 10amp then yes it may take 20 hours, but nobody does that.   My sons Tesla will fully charge overnight from his 7kwh charger on ridiculously cheap off peak electricity or about 20 minutes to 80% from a tesla supercharger. When I visit him (he lives in NZ} he lends me this vehicle so I have first hand experience.

I mentioned 20 hours for a charge from zero to Full Charge; something you might have to do on a long trip. I forget the car, but it may have been a Nissan Leaf.

You mention fully charge overnight, but don't say what the car arrives home with, and you quote 20 minutes to 805 from a Tesla supercharger, with no figures for the starting charge level.

It's in that last 80% that the time exponentially extends, and there are plenty of references to the extended time.

However, the manufacturers have been talking Top Up times,  i.e. leave home, drive for an hour, say 80 km, top up for another hour, drive 80 km back. In one case a truck manufracturer advertised a 30 minute top up for the 30 minute driver lunch break, seemingly unaware that most drivers by their lunch then drive, and don't have runs which allow just a 30 minute top up half-way through the day.

EV is no different to Applications Analsysis on ICE, you pull all the parameters together and then calculate the best vehicle for the job. The truck fleets are focusing on the "Middle Mile" a new term for the run from the Warehouse to the Dealer or retailer - usually very short distances on a return to base basis, and that would appear to be a good EV application.

37 minutes ago, aro said:

Are there any models without regenerative braking? Regenerative braking is the hybrid's main advantage - all the energy comes from the ICE engine, but regenerative braking allows them to capture much of the energy normal cars lose as heat in the brakes.

 

My point was that the hybrid is probably worst case cost and complexity wise. You have ICE, transmission, fuel system, cooling system, plus electric motor and battery. And it's still only 2K over the ICE only model.

Hybrids are not expensive compared with ICE, so you can pat yourself on the back and say you're doing something for the atmosphere, but the engine is emitting CO2 at the same rate as any other ICE engine, but a hybrid is nowehere near an EV.

We have the luxury for EV comparison of real life dealer prices now, and for the entry model cars, the 1.2 litre mini size the going rate for ICE is $19,999 retail. this about matches the pockets of young people buying their first car. The Nissan Leaf - same size (not a family car is $60,000.00 to $62,000.00, and the Chinese MG is $46,000.00. Bottom line is young people can't afford the lowest level EVs. . in the $26,000.00 economy family ICE range, ev EV is around $85,000.00, and in the $30-35,000 ICE range Teslas start over the $100,000.00. You then have to look at why you would pay all that extra money. It's not for CO2 reduction; until we have nuclear power, you are just increasing CO2 output at our power stations by about 20% compared with ICE.              

37 minutes ago, aro said:

 

There are a surprising number of Tesla's getting around these days. I know someone who regularly drives between Melbourne and Ballarat in their Tesla.

 

We traveled up the Hume at Easter, and were passed by several Teslas on the way. The technology is there when the large car makers decide they want to do it. What we do not have is the charging infrastructure for mass adoption.

 

I think we underestimate the capacity of the energy distribution infrastructure we have built around internal combustion engines. I was doing some back of the envelope calculations, and estimated that a single petrol pump delivers the energy equivalent of about a 2 megawatt charger. So a 10 pump petrol station might be the equivalent of 20 MW charging capacity. And there's another one across the road, and another around the corner.

 

One fuel tanker delivering petrol might have equivalent energy to the South Australian grid battery.

I mentioned Australia phasing out electric buses in the 1960s; we also phased out fleets of electric milk and bread delivery trucks and we've never went back once diesel produced a lower total cost of life, and as you point out energy is sold everywhere.

3 minutes ago, facthunter said:

An electric motor requires a miniscule amount of attention and servicing compared to the super complex ICE motors. No warm up no freezing of coolant no heat to speak of No vibration no rusting exhaust systems no drive systems by shafts  and CV joints. It's a new ball game entirely. Nev

Take a look at the electrical system of an EV. Sure the motor is simple, although I'm on my third air compressor motor.

2 hours ago, aro said:

I think Tesla and Toyota at opposite ends of the spectrum show that many EV problems are largely solved.

 

Tesla has range, fast charging and power (see ludicrous mode). Toyota put a battery, electric motor, regenerative braking etc into their hybrid models and only charge a couple of thousand extra on top of the petrol model.

 

If Toyota want to build a full electric car they need a bigger battery and electric motor, but the cost of that should be more than made up by being able to delete the ICE, fuel & exhaust systems, most of the transmission etc.

 

The reason electric cars are expensive is that we don't have the charging infrastructure for mass adoption, and (a) if you can't sell to the masses you have to recoup development costs over a smaller number of vehicles and (b) if you can only sell to a few percent of the population, you might as well target the rich people.

 

Aircraft are a different problem. Cars sit on the ground, they don't need energy to hold them up. With an aircraft, every kg requires energy to keep it in the air. As aircraft get bigger you quickly get into diminishing returns. I don't think that improvements in battery technology will ever solve that problem - there are limits to the energy available from the chemistry that can't be worked around. Synthetic liquid fuels for aviation use seem much more likely to me.

 

https://thebulletin.org/2009/01/the-limits-of-energy-storage-technology/

Just so you know, the automotive industry has responded to the narrative demand for EV by committing to a HYBRID  model in every range for a target of 2020.

A Hybrid is not an EV, an ICE engine still provides most of the motive force, electric power is only used for acceleration or high power demand modes, and the alternator is designed to constantly charge the batteries while the ICE is running, together with, on some models regenerative braking which also adds a charge to the batteries - so 100% charging of batteries + additional charging on deceleration, and electric motors only big enough to contribute to startability and rolling resistance, but just help with grade resistance and air resistance which are much bigger equations.  VERY importantly the Hybrid has the ability to be built on almost standard chassis tooling.

The same people who promise Hybrids progressively coming on line by next year, have been announcing showcars, new factories, and some trial units, but are saying it will take  decade or so to get volume if there is a demand.  After about 30 years of EV claims the Australian market penetration stands at 0.5% so it is not a simple jump from Hybrid to EV, because of tooling, and powering the vehicle to suit startability, rolling resistance, grade resistance and air resistance, given that the last two chew into battery reserves if you have a long climb, say Melbourne to Ballarat, encounter strong headwinds, or wish to drive at Australia's 100/110 km/hr speed limits.

The fast charging being quoted is top up charging. In some cases a full charge can take 20 hours (full charge = travel for the full stated range) Many urban applications can be handled without a full charge, that's true, but this is Australia.

A light aircraft, probably has the limitations you refer to if you want to do anything but a short hop to a holiday destination, and don't forget that one of the most unreliable parts of a vehicle is its electrical system, so it could be exciting, but if there were a breakthough in solar panel design, there's a huge upper area to develop solar power. One breakthough did occur about 20 years ago when printed adhesive film panels were developed but these had a lower output than silicon and seem to have disappeared, probably due to damage factors. A secondary issue with solar power is the horrific cost of all the circuitry required. At one stage I was thinking of building a car for the Darwin-Adelaide Solar race, where the cars have no trouble maintaining 110 km/hr just on solar, but the $100,000 for the solar kit put me off. That may not be so daunting for an aircraft.

17 minutes ago, onetrack said:

IMO, calling trolley buses "electric buses" is comparing apples to oranges. None of these were truly "battery-powered electric", they ran off overhead wires and mains power.

Perth is now trialling some Volvo electric buses on a CAT service (Central Area Transit - i.e. short-route, inner areas, bus service) - but I can't for the life of me, understand why Volvo are charging $1M a bus for the "latest technology" in electric buses.

The CAT makes sense because you have eliminated long range. However for a full Urban Route Bus system, where high power PLUS long range per shift is required, there hasn't been a battery invented yet to do the job. "Trolly" buses were electric buses that had an unlimited supply of full power, but as diesel developed it caught and passed them for range.

17 minutes ago, onetrack said:

And in fact, it's the same with all EV's at present. They're a total and complete rort, and until they can reduce their pricing to acceptable levels, the uptake will be tiny.

I'm sure there's a method in their madness, the manufacturers are all trying to extract every last drop of profit in IC technology, before they're forced to scrap all their IC manufacturing and repair infrastructure.

The electric fork lift trucks I was designing 50 years ago were simple and crude; however we couldn't get the price close to ICE and they eventually priced themselves out of the market. Currently a $19,990 small car compares with a Nissan Leaf at around $60,000, or Chinese MG at $46,000 and it's not that the electric car manufacturers don't know you can't sell cars on that basis.

17 minutes ago, onetrack said:

Electric power will eventually rule, but it will never rule as a stand-alone power source, I firmly believe there will need to be constant backup for the batteries. Whether that is a small on-board genset, a vastly-increased charging network, or a huge network of battery-swap stations, we will have to wait to see what will play out.

 

I'm of the opinion that a battery-swap network has the greatest potential to move electric motive power forward. It's just important that manufacturers standardise on battery sizes and interchangeability, and design quick-swap battery installations.

After all, no-one blinks an eyelid at todays gas-bottle swap network, which works just fine - but which setup was greeted with substantial opposition, when it was first mooted.

Problem is currently no one has to stop work for a couple of hours to do a battery swap now; Nissan Leaf Battery life is around 10 years, replacement set costs around $9500 every 10 years, and labour to do the swap is around $900.00 so a battery swamp in the middle of the day is not on.

Chevrolet US are specifically marketing their electric trucks for 30, 50 or 70 mile rounds, so a little like Perth's MTT where you can do short lead work and have the truck charged overnight for the next day. Once again, the bulk of the market is not catered for by electric.

I too thought of an on-board gen set, and recommended one of our manufacturers attach one to the chassis on their electric trial truck, so their customers who ran it out of power could get a partial charge rather than have to call a tow truck, but it appears even a partial charge would take too long, with some vehicles requiring 20 hours from zero to fully charged, so it's very much a balancing act and a nuisance unless some brilliant person comes up with a battery break-through. I've been waiting since 1986 for that to happen.

17 minutes ago, onetrack said:

Electric motive power has many huge advantages - a vast reduction in the number of moving, wearing components - very little by way of substantial lubricant quantities and regular changes of those lubricants, simple conversion of energy to rotary movement, with no gearboxes, or components changing direction rapidly at dozens of times a second, vastly increased component life - and maintenance and parts reductions, by a substantial order of magnitude.

True, but not the dreamland stuff the EV manufacturers tell you. It still requires tyre, bearng, brake, suspension, body maintenance etc. The Achilles heel of the "Simplicity" argument is that the ICE vehicle these days has a 50% prime cost saving and carts its complex engine and transmission to the tip at the end of its life cycle without rebuilds these days.

23 minutes ago, danny_galaga said:

😅

 

You know there are still people who run stream rollers for fun? Doesn't mean everyone has to have a stream roller.

 

Who would buy an electric Harley? I would if it was half the price, or if I win lotto. I've heard it's awesome fun 😎

 

https://www.morganandwacker.com.au/new-bikes/harley-davidson/2020-livewire/?gclid=CjwKCAjwjuqDBhAGEiwAdX2cj_HxSWivTzd9vLE2lJVmEkeHeKW77I38qzUZggEWIXp3ap-Cc2MxCRoCj6kQAvD_BwE

 

 

23 minutes ago, danny_galaga said:

 

Electric is a simple equation; you can have power but not range or range but not power.

Just imagine a patched Harley Rider waving traffic pas him as he does his trip from Brisbane to Bundeberg!

You can ride in an electric tram in Melbourne.

Melbourne like Perth, Adelaide and a few other cities had electric buses from early in the 20th century, but they all dumped them by the early 1960s.

On 16/04/2021 at 8:04 PM, RFguy said:

OK on that.

In terms of reducing piston temps, for this engine, any other suggestions ?

 

You can cool the combustion chamber with richer mixture.

19 minutes ago, RFguy said:

Turbs, WHen I was a lad (18) I experimented with asymmetrical constrictions (IE different resistance out than in)  in inlet ram tubes to change the behaviour of the inlet any in prescence of the reflection wave from the closing- closed inlet valve.

 

It ended up being VERY dependent on gas velocity , and had a very small sweet spot.

 

Going to much larger inlet open time  reduced the reflection pressure wave ALOT.

 

IE the inlet gas velocity was slowed down by the action of the slowing and reversed direction piston as it got through BDC in intake stroke, with the inlet open way into the compression phase from BDC to TDC.  that was no good for low RPM.....

 

golly the things you do when ya young and have plenty of time.

 

 

 

 

I was just focusing on how the movement and expansion/compression of the gas during the cycle changes to end temperatures dramatically and is an intergral part of finding how to optimise aircraft engine cooling. 

Valve timing and inlet exhaust diameters with carburetted, naturally-aspirated engines is a fascinating experience in itself. On one engine I was using over 180 degrees overlap. It didn't work too well below about 4000 rpm and at times would backfire and spit carbies off, but the power band increase at 8,500 was explosive - a very tiny sweet spot. If you got ahead you could usually place in the top three, but if you got into traffic on a corner and forgot that sweet spot, the car would do a 180 instantly.

There are optimums for intake pipe diameter too. People buy the biggest throat carbies they can and are worse off than they were with throats half the size.

1 hour ago, facthunter said:

Gas in the ports doesn't reach sonic speeds, it's the pressure waves that do and that's what you can tune to with varying lengths.. Similar to waves on the surface of the ocean  where the wave speed has nothing much to do with the current  movement in the water underneath.. Nev

Yes, I just rushed the story, tryingf to use sausages to visualise that the flow through an engine was like a series of sausages starting/stopping/starting etc.

1 hour ago, skippydiesel said:

Turbo me old  mate - Bit hard to follow -Lot of non engineering words to confuse matters - However I get your gist.

 

The "expansion" stroke usually referred to as the power/combustion stroke, does not reduce pressure in the chamber - if it did you wouldn't get much in the way of power being delivered. 

 

Intercoolers, sometimes called after coolers, pretty much only apply to exhaust turbo (possibly super) charged engines.

 

Forced air (turbo/super charged) engines do not "give a smaller volume" of intake air - they cool the air, allowing for a higher density/oxygen content. This  allows for more fuel to be burnt. Can also assist with scavenging and cleaner/less polluting combustion.

 

As for inlet/exhaust optimisation on aero engines - in general these "tuning" techniques work better on high rpm engines. eg Rotax 2 & 4 strokes (land based vehicles). Slow revving LyCons will get some benefit but it will be minimal.

 

The whole consent is known as Volumetric Efficiency - describing the ability of an engine to process the fuel air mixture.

 

 

The Power stroke starts with the gas mixture confined to a tiny space above the piston. As the piston travels down, the gas expands and the byproduct of expansion is cooling.                                                                                                Intercoolers and aftercoolers are two different products. The Intercooler cools the air before it reaches the turbo pump section and the Aftercooler cools the air after it comes out of the turbo blower. I was just explaining the principle that by cooling the air you can stuff more in during the compression stroke.                                                      The principles I discussed work for all ICE engines at all rpm. You can tell an engine builder knows what he is doing by listening to the engine ticking over at 500 rpm.                                                                                                              Although I did mention power increase due to better breathing, the aspect of what I was discussing here relates to combustion process and it's various temperatures, but high and low which overlay the other piston temperatures discussed in earlier post; it's a bigger moving target and you can change the piston temperatures by allowing and engine to breath in better and breath out better (non-technical terms I know), and it makes a lot of difference if through using a plenum intake chamber, one cylinder breathes better than another, and the same with a common exhaust manifold.                                                           

1 hour ago, skippydiesel said:

Turbo me old  mate - Bit hard to follow -Lot of non engineering words to confuse matters - However I get your gist.

The non-engineering words were to make it simple for more people to understand the principle. I wrote it on the run from memory because in about a decade of discussions on this subject these critical components of the engine cycle have been ignored, so we go round and round in cicles without a solution. By factoring them in, there can be an understanding that perhaps things like carburettor main jet size to suit what's going on might be very important. 

You can get a fully drafted and edited version in engineering terms by buying the Phil Irving book "Tuning for Speed", this morning selling for $2069.00 in hard copy.

In addition to the varying temperature phases and their effects on pistons above, there are other factors controlling those temperatures.

The compression stroke is to compress the volume of charged gas trapped when the intake and exhaust valves are close. A byproduct of compression is heat, so the piston top gets a charge of heat.

Then you get the heat of combustion.

The expansion stroke reduces the pressure in the chamber, and a byproduct of pressure reduction is cooling (a refrigerator works by releasing gas through a valve over and over again).

So the piston top is rapidly cooled again.

This is overlaid by the efficiency of the intake system and the exhaust system.

Manufacturers have to build to a commercial price, so if you have the skill and patience it's not hard to double the power output of an engine.

Fitting an Intercooler cools the slug of air ready to go into the combustion chamber. This gives it a smaller volume, so on the intake stroke. More mixture enters the chamber, so the expansion is greater poducing more power.

Phil Irving was the early genius using better breathing to produce more power. If you visualise the breathing of a 4 stroke engine, a schematic might show a series of sausages or slugs of air/mixed air/exhaust flowing through the engine when it is running. These slugs reach sonic speeds, but when the valves close for the compression stroke the incoming charge slams into the closed valve and a sonic wave bounces back, taking the column of mixture/air with it. This can be back out into the plenum chamber. If we squeeze the plenum chamber in various places we can minimise the "waiting" volume of mixture and make it equally available to all cylinders. Or we can take the next step and fit separate intake pipes. These contain the slugs as they form. when the sonic wave bounces back it reaches a point where the intake cycle sucks the mixture back in also at sonic speed. The momentum creates a point in the tube where, if the carburettor is fitted at the turnaround length, when the intake needs a charge, it is ready to come down the pipe at sonic speed, and charges the cylinder with a lot more mixture, which when trapped, produces a lot more power. The exhaust is now the remaining blockage in the system, but the moving slugs of gas are also having a sonic effect at the exhaust where the sonic waves are going out, but then coming back in where they collide with the next outgoing wave. If the exhaust pipe is shortened to the point that the outgoing sonic wave exits the pipe instead of coming back in and slowing down the flow, then the exhaust gas can expand much faster, and as we know, expansion means cooling. 

You can understand from all these variations in pressure and temperature why EGTs don't give you much more than broad information after it's all happened.

If you transfer this to an aero engine, you can see we don't have enough space for precision intake, or multiple exhausts, but we still have a lot of options with mixture, plenum and partial exhaust work, the aim not being to produce more power, but to lower combustion temperature.

There was a landing strip at Orchid Beach Resort, but my exerience with the, at times procession of 4WD traffic is that I wouldn't be trying to land on the beach.

It looks good, but once the holiday makers and 4WD hirers get on, head on passing can be on the left or the right based on a last second indicator flash, and I've been pushed into the soft sand often, and close to the water as well. You couldn't control the situation once you committed to land, and taking off would be much the same, so it wouldn't surprise me if a decision had been made to prohibit operations. How a commercial operator would be excepted is another question because the risk is just as great. I wouldn't operate a helicopter their either with heaps of inexperienced 4WD drivers with anything up to tents and bikes on their Land Cruiser roof racks and their thirst for close up videos.

39 minutes ago, anjum_jabiru said:

Any reason why one of the cylinders would lose compression in  mid-flight?

Several.

Engine running lean, combustion chamber (1000 - 1500 deg) temp rises and softens a valve stem. Valve tilts sightly and you've lost compression. It can then smack itself flat if the Combustion temperature is still high, tilt more and bash the seat on one side, snap the stem and cruise around bouncing on top of the piston, embedding itself in the top or taking out part of the top, or again with the combustion chamber too hot (usually running too lean) soften (burn) the exhaust valve eroding material off it until it leaks like a seive.  I think I've managed to achieve all of those things.

.........pleased with a 15 strand bull lead he'd made for the Royal Adelaide Show; the rings had been made from pure silver, mined on Starlight Station, and Sid had decided to show the Limousin bull "Doyafeellucky" from Backwater Station.

The problem was ..........

.........a liberal donation to Twiggy's brand new RM factory in Adelaide where it belonged, not that there was anything wrong with peasants from Upper Silesia making boots for Australian Ringers. 

Not many people know that old RM was the strapper for the Kidman properties, and he could make ten pairs of boots faster than an Upper Silesian could make one pair, and the soles didn't fall off in the first week either.

RM had to work fast because Sid Kidman had 104 Stations with three or four Ringers on each, so he had to work hard and fast, killing his own Limousin bulls, which was difficult when all Sid issued was a standard Sheffield Pocket Knife, but he made do and daily was turning out boots, belts, watch straps and covers, stockwhips, bridles, saddles, and still had time for the Sunday buck jumping competition.

One Sunday night ...................