Ian

10 hours ago, Garfly said:

https://www.avweb.com/aviation-news/avgas-coalition-petitions-dot-and-faa-to-retain-100ll-during-transition-period/

The transition should have been implemented long ago.

I'm actually on the airports side on this one. There's been more than enough time for an orderly transition and the science behind lead toxicity isn't going to get better. In fact is has been growing worse over time.

The bad news is that any plane that can only run on leaded fuel is worth less. So consider whether STC etc

The lead crime hypthesis is an interesting one.

https://en.wikipedia.org/wiki/Lead–crime_hypothesis

On 10/05/2022 at 6:23 PM, facthunter said:

What about all the lead dust in the roofs of houses in places like Broken hill and Mt ISA? What % of lead mined goes into Petrol? Piston aero engines would be quite useless without it as tetra ethyl lead. I don't like it but just asking.

    In the USA the lead that kills people comes out of firearms.. Religion is what harms their brains.  Nev

Children in and around Broken Hill are being subject to environmental lead loadings which are likely to lead to mental retardation and behavioral issues.

https://www.phrp.com.au/issues/march-2022-volume-32-issue-1/blood-lead-levels-among-broken-hill-children/

https://theconversation.com/toxic-playgrounds-broken-hill-kids-exposed-to-poisonous-dust-32325

The US now places recommends children have below  3.5 μg/dL.

https://www.cdc.gov/mmwr/volumes/70/wr/mm7043a4.htm?s_cid=mm7043a4_w

Piston Engines generally work just fine without TEL. An estimated 80-83% of the US GA fleet could run on mogas.

https://generalaviationnews.com/2012/07/12/new-study-shows-autogas-can-power-80-of-piston-aircraft/

For the other 17% it might be time to look at proven measures such as  MW 50

That's why I think that mogas is actually the GA fuel of the future. In a world looking to phase out fossil fuels the likelihood of creating an entirely new fuel stream to address a decling GA fuel market is pretty unlikely. I wouldn't invest in that business plan.

For starters given a choice between $2/L and $3/L to do the same job it's not a difficult choice, most people will follow their wallet.

There are a number of issues with the ASIC Card beyond their basic utility value. Their fundamental role was to reduce terrorism style attacks and it about as effective as requiring people to wear a T-shirt saying "I'm not a terrorist".

1. The card is only valid for a short period of time compared to other credentials. Passports are valid for 10 years and licences for 5.
2. The cards are just bits of plastic and don't conform to baseline security standards compared to other Government or commercially endorsed identifiers no secure element, no machine readable component. They have a holograms however these aren't great security and can be forged relatively easily

If there's a requirement for security checks to be done, CASA should provide a proper electronic license rather than a paper based one which has a simple colour coded symbol affirming that you have undergone a security clearance and are suitable to have airside clearance. 

The real flaw in ASIC is the fact the crew of a foreign aircraft are exempt. So someone with a uniform and a cardboard ID is off the hook. Effectively the crew of a charter aircraft can wander around the airport while it's parked in the airport. So if someone chartered a foreign plane they could effectively claim that they don't need an ASIC as long as they were performing an operation. I think that the term half baked applies.

From the act, Aviation Transport Security Regulations 2005

3.05 Crew of foreign and state aircraft etc
Despite regulation 3.03, the following people need not display an ASIC in a secure area:
(a) a person who is a member of the crew of a foreign aircraft (other than a state aircraft) that is engaged in a regular public transport operation or a charter operation and who:
(i) is in the uniform of the aircraft operator; and
(ii) displays appropriate identification issued or authorised by the aircraft operator;

With hydrogen fuel the logistics at airports would be a huge issue. For example KLAX used about 50M Barrels a year which is about 26 million L a day.

Currently at LAX there are multiple airport feeds from offsite storage allowing multiple fuel companies to distribute fuel via an underground fuel network which is pumped into planes

There also need to be the ability to unload fuel, hydrogen especially would need to be offloaded to keep it cool.

The whole system would need to operate at cryogenic temperatures in all sorts of weather conditions.

You'd also need to operate this system in parallel with existing fueling systems for a significant period of time.

But the challenge would be the handling of a potentially explosive mixture compared to a relatively inert one in the quantities required in close proximity to thousands of passengers would be difficult. So you might force refuelling to be conducted in an area away from passengers.

It just sounds hard and dangerous. More likely that a synthetic carbon neutral fuel will be developed which can use the same infrastructure.

LPG is a plane could be interesting. Refueling might be an issue.

There have been a few turbine engines over the years converted to run on it.

Some Japanese car companies, especially Toyota are doubling down on non-battery technologies even though the rest of the market appears to have moved on.

https://www.guideautoweb.com/en/articles/61894/toyota-chief-scientist-s-latest-remarks-on-evs-fuel-controversy/

14 minutes ago, octave said:

Refueling seems to be much like filling a LP gas car.

But the fuel isn't liquid, it's a compressed gas with the same volume penalty.

15 minutes ago, octave said:

In 2021 there were just 38 registrations of Hydrogen cars

So about a couple of million dollars of infrastructure per vehicle, the investors must be really lining up for this opportunity.

Hydrogen is just a difficult technology which is glossed over by people who see it being made by solar panels and water. I keep thinking that I'm missing something here but I haven't found it yet.

It appears to be mostly marketing hype, and when you dig a little deeper it appears to be the fossil fuel companies pushing the Hydrogen pipe dream by creating a niche that requires more of their product. One day you'll be able to use green hydrogen but in the meantime here's a bucket of brown hydrogen.

2 minutes ago, RFguy said:

and shortly, fusion. 

I suspect everyone who's alive now will be dead before fusion can be implemented profitably. If you want to go Nuclear there are many simpler avenues to explore which look quite attractive.

There's a nice brief by a former fusion scientist. Not very optimistic unfortunately.

https://fusion4freedom.com/former-fusion-scientist-on-why-we-wont-have-fusion-power-by-2040/

1 hour ago, turboplanner said:

Solar has been sold on the basis of free energy which it is, but it's not cheap.

https://energycentral.com/c/ec/effect-intermittent-renewables-electricity-prices-germany

Solar is actually very cheap and profitable up to a point of about 15% penetration. This is the argument presented in the above link which has a significant degree of rigour in its study of the German market.

Quote

In conclusion, it can be estimated that solar and wind operators will receive a premium of 10% at ~0% penetration, but will have to give a discount of 13% at 20% penetration. It is assumed that this premium/discount varies linearly between these two datapoints.

As the cost of solar and other renewable sources drops this figure will be profitable at slightly higher percentages however past that point of penetration you require increasing subsidies.

The costs and efficiencies associated with large power stations and transmission has changed over time and is changing again as different costs come into the system. Some existing power stations aren't particular good at load following. As soon as there's a price on carbon emissions those transmission losses become even more expensive and a distributed architecture might make more sense.

I don't think that  the term flagging growth in electric vehicles is the right term worldwide. Possibly Australia's 1% showing, it could be the tax system which sees a tax of 33%  on a Tesla compared to 5% on a 4WD might have something to do with it.

Unless something changes dramatically FCEVs have lost the market. It appears that battery vehicles have won and the people pushing the alternate technologies have lost.

On another note Hydrogen can be used as a diving gas although it has a signficant risk profile.

Haven't you just repeated what was stated on the first line. I think that we're saying the same thing.

Also, from a mathematical perspective, in terms of losses isn't the cascading loss pretty much the same as the loss when sending the power direct as AC power loss is pretty much linear with HVAC? See graph below.

Basically it's far more efficient, and generally cost effective to spool up local power.  The national grid provides stability in a crunch however it does it inefficiently giving you time to spool local power. Otherwise you have a Texas style event which is far more expensive.

The graphs below compare AC and DC

However if power is very cheap (think Solar) you don't care as much about losses it becomes more reasonable, however the capacity of the links themselves are costly, about 1 Billion for the HVDC link between France and the UK. So basically even with very cheap power a long way away you still have an issue.

Anyways this is a way away from airplane fuels and whether Hydrogen is a good or bad fuel. Personally I think that Hydrogen is a pretty silly fuel for plane for the following reasons.

1. It is expensive.
2. It is volumous, the only possibility is cryogenic storage. Energy density/Volume is low.
3. It burns in very low concentrations, great inside an engine but a bit of a bummer with leaks and sparks. Modern turbines burning kero type fuels was seen as a huge advantage.
4. It is difficult to contain, it permeates a number of metals causing issues and it is very difficult to stop leaks.

However I may be wrong.

Generally you want to generate power near where you consume the power.

If you're storing the power you want it near where you consume it, because if you have 30% transmission losses your battery or generators need to be 30% larger if they're remote.

The costs associated with these project is mind boggling, the solar project to supply Singapore with 20% of it's power is 30Billion, Singapore has about 5.6 million people and no heavy industry. The project consist of solar panels, some battery storage and a High Voltage DC link. That's up there with NBN's cost across Australia. It's effectively 1.2 million people for 30B.

Australia used at least  265,232 gigawatt hours (GWh) in calendar year 2020, and people generally want more power. If we add vehicular transport to this you can assume that we'll need another 50% additional

9 hours ago, kgwilson said:

The potential storage capacity is 67,000 gigawatt hours. https://reneweconomy.com.au/want-energy-storage-22000-sites-pumped-hydro-across-australia-33174/

Has anyone actually looked at the identified sites in this study? Below are proposed storage areas in the Araluen Valley near Canberra. Given the environmental/ownership and community issues associated with development on this scale does anyone actually think that this is feasible? People complain when a plane or drone flies overhead, let alone a gigalitre of water perched above their properties.

If your requirement is that it needs to be carbon neutral then you have some hard decisions. It's a bit like being diagnosed with cancer, you can pretend it's not an issue and the consequences are pretty bad. Treatments are also pretty bad but better than the alternative. Anyone with half a brain goes down the treatment path.

12 hours ago, turboplanner said:

You might be aware that the one of the Greens policies in the current Federal election is that Australia is one of the worst EV performers in the world and if elected to Government they are going to subsidise EV, apparently to be come a leader.

The key point that you're missing is that to lower carbon emissions electric cars are amongst the easiest deployable solution. Planes, concrete and steel are not so easy. The policies of all the major Australian parties are pretty dumb and I'm really struggling to identify a party where their policies are based on sound science rather than hand waving. I don't like ideologues which further limits the choice.

Assuming direct carbon capture from the atmosphere you end up with a premium of about $1/L, this doesn't assume storage costs or plant costs. 

If the above premise of zero Carbon emissions is true, at a fundamental level, either electric cars are going to become cheaper, petrol cars will become more expensive. The concept that the status quo can remain is akin to Steve Jobs meditating to cure his pancreatic cancer, he later said that he regretted not adopting conventional treatments earlier.

There is also a lot of infrastructure work such as how the power grid will scale to replacing the oil distribution networks and questions as to where that power will come from. I'm not sure if most people actually grasp the scale of this problem and how ineffectual the proposed solutions which revolve around intermittent power are. Renewable power is cheap up as a top up power source, the costs and risks associated with making it your primary source are very high. Below is a study of German electricity prices and the impact of renewables.

https://energycentral.com/c/ec/effect-intermittent-renewables-electricity-prices-germany

At a fundamental level people need to pay for plant costs, if you build a source of electricity that can supply power when solar and wind aren't running you'll make people pay for a return on your investment. If this is only in the windows when the sun's not shining and the wind doesn't blow times you just make them pay more when they really need it, so you end up paying for both.

Some salient points considering that Europe is further down this path than Australia. We should learn from them.

• The cost of power in France is about half the cost of power in Germany and their emissions are lower.
• The largest exporters of power in Europe are France, Sweden and Norway.
• The greenhouse emissions per capita of European countries https://www.greenmatch.co.uk/blog/2019/10/greenhouse-gas-emissions-by-country
• While Germany is pro renewables no-one wants additional renewables in their back yards and their deployments have stalled due to litigation.

The key question is what do these countries have in common and can their successes be applied elsewhere? For example Australian is flat and dry so hydro isn't an option. Snowy Hydro2 is a bit like loaves and fishes.

5 hours ago, facthunter said:

Water with surplus solar or wind electricity. It doesn't come more cheaper than that.  Nev

Yes it does, compressed air or pumped hydro is cheaper storage. And batteries are just way more efficient.

https://www.spglobal.com/marketintelligence/en/news-insights/latest-news-headlines/hydrogen-technology-faces-efficiency-disadvantage-in-power-storage-race-65162028

https://theconversation.com/hydrogen-cars-wont-overtake-electric-vehicles-because-theyre-hampered-by-the-laws-of-science-139899

https://www.volkswagenag.com/en/news/stories/2019/08/hydrogen-or-battery--that-is-the-question.html

Battery electric vehicles have basically won the race. All urban transport will go this path.

Current solar systems have about a 15:1 return on embodied energy over their lifetime. So lets allow for a 20:1 ratio in the future. With hydrogen having a round trip efficiencies of 18-46% that implies a system energy return of less than 10:1.  This doesn't allow for commercial realities like profit etc when you're trying to balance your budget.

Then on top of this you're going turn it into Ammonia with the inherent inefficiencies of this process.

If you wanted to make hydrogen efficiently and economically I'd just be using high temperature nuclear with a direct thermal process such as the Iodine Sulfur process. That way you can make it in your backyard so to speak. I suspect a number of countries with steel making industry will realise this rather than buying expensive NH3.

On 17/04/2022 at 12:18 PM, facthunter said:

Too much surface area for a given volume so thermally bad.

Yes not as thermally good as a cylinder however if you read the NASA paper on their engine they achieved fuel consumption better than any of the current turbines or reciprocating engines in a lighter package, yes a cylinder is better however it's overall efficiency that counts.

All engine design is a compromise, look at the valves in a cylinder head. The sleeve valve engine was used by the British in ww2, it provides better volumetric efficiency at the expense of complexity. Standard reciprocating aircraft engines are a bit shitty and don't seal particularly well either, just look at the amount of oil they burn and the amount of piston slap that is deeded acceptable.

Actually the seals on the rotary operate best at higher RPM, it's the low throttle times where the engines typically struggle so constant high throttle should be a boon for them. One of the reasons to the poor efficiency of turbines is that they have no seals.

In a nutshell, the power to weight of a rotary is significantly better than a normal piston engine, even with the  efficiency compromise of a flat combustion chamber, NASA managed to get fuel economy out of the engine that significantly beats any of the existing reciprocating or turbine engines (0.375). If you read their analysis they compared diesel, turbine and rotary engine for their potential as a next generation engine design for aircraft and from an engineering perspective decided that the rotary showed the best promise from a weight, vibration, cost and fuel consumption perspective. That's why they spent money on it development. However development pretty much stopped when some of the associated military contracts were cancelled and the commercial sponsors changed tack.

The idea of running on turbine fuel or diesel appeals to me. More easily available in both the short and long term.

I'd be happy with any fuel that is environmentally sound, is low cost and provides equal range to existing liquid fuels. I won't miss the racket if it was electric however I can't see batteries improving 10x or hydrogen becoming a fuel. Hydrogen just too big and expensive, liquifying it costs even more and we can't make it efficiently.

There's a nexus of cost issues when flying, the initial buying price, airframe maintenance costs, engine maintenance costs, fuel costs and then storage airfield costs. Everyone needs to make their own choices in this space. While turbine engines have wonderful TBO maintenance and virbration characteristics unless their efficiency improves radically I can't see one really appealing unless I decide that I must use a turbine. 

Fuel from both a greenhouse gas and political instability point of view is likely to stay high so that's going to be on peoples minds.

I came across the PDF "Stratified Charge Rotary Engine", where they achieved a BSFC .375 running on turbine fuel, the progress that NASA made with stratified charge Rotary engines was significant. The engine weight was 480lbs for 400HP dry.

While rotaries have never had enormous lifetimes they don't have many moving parts and their motion is closer to a turbine than a reciprocating engine.

7 hours ago, turboplanner said:

Turbines are now quite common in RC aircraft now, so someone has found a way to make them economically.

Their fuel consumption is pretty poor even by turbine standards. There is an paper on how they might be made more efficient. I think that this one states that JetCat overstates their thrust figures significantly as well.

Going small with turbines is hard work without the support of deep pockets realise high compression and turbine temperatures.

Looking at this I came across NASA's analysis of rotaries where the power to weight and low vibration were seen as being very attractive. 

While rotaries are thirsty they're still better than small turbines.

Back to the topic at hand, I'd be interested to know what the ballpark price is for this engine and it would be great if someone could really upset the current status quo in the current market.

I'd like to understand the SFC figures a bit more, the fuel flow figures are quoted at 150HP however optimum cruise is 180 HP, I don't know enough about recuperators to know how this moves the optimal power settings.

Maybe :-), not sure about the high temperature properties though if you were using it in a hot sections. The key message was that I don't think that going from wood to metal was a quantum leap, it was just a bit easier to engineer.

The key problem with wood as an engineering material is its lack of consistency compared to a metal alloy and the associated fudge factor required when building. Laminates reduce this factor allowing more of an engineered approach and allowed their use in the Mosquito. Rotol propellers for the spitfire were also made of wood in WW2.

Certainly wooden props are far easier to certify than their metal brethren and they don't have the nasty fatigue issues associated with metal props. MT Propellers manufacture their "Natural Composite" line of constant speed propellers. For instance MT-Propeller natural composite blades are certified for unlimited life and can be repaired in the field or at 60+ overhaul shops worldwide.

Australian Hardwoods especially are significantly stronger than traditional northern hemisphere timbers and massively undervalued. For example Grey Ironbark has a tensile strength about 3x that of Oak, the traditional symbol of strength. 

Another less well understood property is dampening which the graph below shows.

1 hour ago, onetrack said:

They simply believe it's the next quantum leap in technology, on a par with the move from wood to metal in airframes.

Wood is actually has a pretty good strength to weigh ratio, generally equivalent to aluminium and used correctly can provide excellent results. For example the de Havilland DH.98 Mosquito, in 1941, it was one of the fastest operational aircraft in the world. 😉 and called the wooden wonder. It also has a much lower radar cross section so you can claim that its stealth.

2 hours ago, onetrack said:

As to Ian's opinion of a "staggering increase in cost", it appears the second major driver of CMC technology use, is not just CMC's ability to handle temperatures of 2400 degrees (around 1000 degrees higher than the best titanium alloys) - but that incorporation of the CMC technology into turbines results in manufacturing cost reductions

While I really like ceramics and I hope that you're right in terms of cost, they're a bear to machine. CMCs have been used for combustor and turbine housings however turbine blades are precision components with very high tolerances. The materials being considered are hard like SiC in ceramic matrices often of equal hardness. Very hard compared to metals.

I suppose cost is a relative thing, when you're an airline fuel savings may drive their introduction. Ceramic disks are relatively cheap in comparison however I don't see many cars with them.

17 hours ago, onetrack said:

Interestingly, the race is on to seriously redesign and upgrade the PT6 with CMC's in the turbine blades, to produce some staggering turbine improvements - on every measurable level.

However I suspect that the end result will be a staggering increase in cost far beyond the budget of the people on this list,  exotic materials = high costs.

The PT6A-66 (as used on the Piaggio P.180 Avanti)  has a fuel comsumption of 380g/KW whereas the Junkers Jumo 204 used in the Junkers Ju 86 uses 211g/KW.

As the image below shows as soon as you go below 1000hp your fuel consumption for any commercially available turbine is pretty poor. I've created a red dot which shows what a two stroke compression ignition engine built in WW2 achieved, (Junkers Jumo 204). The green dot is an O235 for comparison.

1 hour ago, Geoff_H said:

Far too general a statement.  Quality gas turbines can get to 40% efficiency with expensive Blade material and multiple compressor stages.  Higher than all but the most sophisticated piston engines.  Cheap turbines do have poor fuel efficiency.

Hi Geoff, do you have any information on the relative efficiencies of smaller low cost turbines and their ability to throttle?

Based upon this specific fuel consumption table anything small has pretty horrible fuel economy and this is at maximum efficiency not part power.

One of the reasons why jets fly at high altitudes is to achieve the best angle of attack because they can't throttle efficiently. An aircraft that can throttle efficiently can achieve maximum range regards of altitude, you simply need to slow down to achieve the best angle of attack. Flying higher reduces trip time but does nothing for efficiency. (However you might gain some by flying lower)

I'd actually like to see someone makes a smaller Junkers Jumo 204 even in 1940 the fuel numbers were pretty good.

19 hours ago, pmccarthy said:

Demand far exceeds supply, price will go way up and we will not get our wind, solar and battery goodies. Hence the IC engine will be around much longer than current predictions.

I don't think that supply issues will constrain the transition to away from fossil fuels for vehicles, supply is easy to fix. Issues associated with dispatchable power and distribution will have a greater impact. As soon as you have to pay for carbon capture instead of polluting those EVs start to look really good.

For instance the cost to supply Singapore with intermittent Solar from the NT was ~40B to supply 20% of their power needs some of the time using HVDC.

On 08/04/2022 at 12:39 AM, pmccarthy said:

We will not have the mineral raw materials to build electric aircraft, or cars, in the numbers required. This is a fundamental blockage, not something that can be overcome by more spending. For example, even if exploration and development of copper mines is accelerated to the maximum, we will have a deficit of one million tonnes of raw copper per year for the next twenty years. And other minerals are similar or worse.

In relation to cars, this isn't a view being borne out by industry except Toyota whose strategic direction is increasingly at odds with the market. IC cars are going the way of the dinosaur like it or not, to believe otherwise is a bit niave.

Your concerns relating to limited availability of materials don't really stack up. While copper's a prime choice for things like engine windings materials like aluminium are generally more cost effective and available, yes you lose some size and efficiency advantages. This is why the power cables near your house are aluminium and not copper. It's also why everyone doesn't use 98 octane fuel.

Lithium is a finite resource however there's actually a lot of it about and it's an industry in its infancy. You can also make Sodium Ion batteries which don't really have the same resource constraints.

I can't see electric planes for anything except training platforms where the pilot does 10 circuits and then lands or short hop metro flights. Trucks are also another matter however I'm expecting a bit of a resurgence in rail freight in the coming decades.

I wish the builder well and I'd like to see turbine engines going forwards however I think everyone struggles with fuel costs and turbine efficiency generally means higher costs unless you've been unusually clever. The other problem with turbines is that they don't throttle well so you don't get the chance to reduce that fuel burn once your at altitude.

That being said there are a number of markets where a cost effective turboshaft engine would be very attractive.