Ian

Hi All, I was wondering if anyone was using the equivalent of MW50 or MW30 or water/oil injection to provided greater knock margin and cooling on engines. Water 99% 1% oil was most effective however it could freeze. NACA provided the following in the 1943 https://ntrs.nasa.gov/api/citations/19930091835/downloads/19930091835.pdf I know that there is a STC'd version was/is available but it sounds a little pricey for what is a simple system. A few benefits are; lower head temperatures at higher power settings Lower fuel consumption Increased knock resistance allowing lower octane fuels or higher compression pistons. removal of engine deposits It certainly seems simpler and less work than many other modifications.

I agree, and it's never been more true than at the moment with the future for mass produced IC engines looking pretty bleak. However history has demonstrated that keeping engines going remain possible for those with a desire to do so especially if you choose an engine that has a community the problems are soluble. For example if you go with a 13B or 20B engine you can buy mounts off the shelf and there's a whole industry devoted to parts. http://www.cozygirrrl.com/aircraftparts.htm Turbine engines push the limits of material science and making them moderately efficient and lightweight is prohibitively expensive. If you look at the BSFC figures there's no aero turbine engines with great fuel consumption, the Europrop TP400c recent generation expensive turbine engine consumes 213g/kW and your BMW BMW N47 2L consumes 198g/kW It somewhat ironic that the rotary engine which has for 50 years been considered a thirsty engine has been considered as a more efficient combustor for turbine engines. It will be interesting in the future as there's a greater push for carbon neutral transport whether the advantages of turbine engines will remain. I can't see a replacement however if fuel costs rise significantly other choices might become feasible.

I think in terms of power to weight the rotary wins, both the 13B and 20B have been used successfully. They're also easier to strip and reassemble than other engines. Subaru engines also worth a look, the key advantage is their form factor is a flat four which is similar to existing air cooled engines. I'm not sure if the marcotte is still around http://www.sdsefi.com/air14.html or http://www.glasairproject.com/Marcotte/Contact.html The problem with any PSRU is that they are often built by people without the engineering knowledge or equipment to properly analyze issues such as harmonic, tribology or torsional effects. So any design which has lots of miles on it is preferable. There have been a lot of people in this area with more sales and marketing ability than engineering knowledge. Eggenfellner probably fits into this class. Also from a safety point of view flying something that either has a low landing speed or has two engines might be wise when using automotive engines. Not that automotive engines can't run continuously and reliably at WOT, it's simply that there's a lot to get right when going down this path and you're generally doing it all yourself. It's easy to ignore/dismiss potentially dangerous installation issues. There's a nice article here about subaru vehicles being run continuously at high speed and high rpms which should put the whole "not designed to run continously at WOT" to bed. https://subarudrive.com/articles/15-2-legacy-endurance-record-attempt The EJ20 engine used in this would probably be a good starting point. Personally I think that automotive engines have a raft of advantages over the existing aviation engines, mostly due to the fact that they effectively leverage an additional 70 years of engineering knowledge.

Self driving I don't really follow your logic here and I not sure what you are trying to say? Autonomous cars drive by themselves, so if another car nearby goes haywire it will deal with them in the same manner as one of the many thousands of nuts currently behind the wheel. All bets are still on because they're autonomous they just react to another crazy driver. It's a little different being the occupant of the vehicle going crazy though but then you're in the same situation as taking a lift with someone and realizing that they're a pretty crap driver. Or were you trying to make a different point? Any moving powered object has a temporal bubble which indicates it's possible locations at some future point in time, the greater the time the larger the bubble. It's just maths and number crunching, some of these states are unlikely and that's what the systems try to work with on a crowded road. However the temporal bubbles can only be projected fractions of a second ahead without intersection. With planes it's much easier as there's so much more room that you can largely stay outside these temporal bubbles even when they're projected minutes ahead. There's a few stats published by tesla. https://www.tesla.com/VehicleSafetyReport In the 4th quarter, we recorded one crash for every 4.31 million miles driven in which drivers were using Autopilot technology (Autosteer and active safety features). For drivers who were not using Autopilot technology (no Autosteer and active safety features), we recorded one crash for every 1.59 million miles driven. By comparison, NHTSA’s most recent data shows that in the United States there is an automobile crash every 484,000 miles.

The problem with helium is that it a finite resource and literally disappears into space. While lots of airships might seem like a good idea it would tap out all reserves pretty quickly. Unless we start making it using fusion but that's pretty unlikely. Recently the price for helium has been about $20L up from a couple of dollars a decade ago so this might kybosh the option of more airships in the future.

Total automation of the flight envelope would probably be both safer and cheaper however people don't make decisions based on logic. That's not to say that there wouldn't be incidents however from a computing perspective flying and landing isn't that difficult. Especially while you have an operational GPS system. However systems need to be designed effectively with the dumb design decisions associated with the boeing max where a single point of failure model was seen as appropriate. Essentially this was a half arsed attempt at automation. Airbus used triple reduncancy for the same sensors. https://www.faa.gov/sites/faa.gov/files/about/office_org/headquarters_offices/avs/CFIT_brochure.pdf From the above the top two in GA are Loss of control in flight Controlled flight into terrain Interestingly commercial aviation fatalities shows the same no 1 and 2 https://flightsafety.org/wp-content/uploads/2017/07/CFIT-Report-1st-Ed-2015.pdf Another fact is that controlled flight into terrain has reduced markedly over the past few years however controlled flight into terrain has remains significant. https://www.iata.org/contentassets/b6eb2adc248c484192101edd1ed36015/loc-i_2019.pdf

You should just be able to engage and instructor to teach you the skills. Unfortunately it's a bit more broken than that. The current approach to flight training is pretty archiac and geared toward propping up a business model rather than achieving an outcome. An independent review should occur. There are also training shortcuts which don't appear to have any real merit apart and have occurred simply because of lobbying by the organisations involved. For example a student who studies at an integrated flight school requires fewer hours to achieve the same qualification. https://www.casa.gov.au/licences-and-certificates/pilots/pilot-licences/commercial-pilot-licences/getting-commercial-pilot-licence-cpl The continued requirement for a classroom, given that students at most universities only go to uni for exams (not during covid) and practicals and most students watch the lectures at times of their own choosing the requirement to have a physical school is a bit dumb. It would be significantly better if the following could occur. An independant instructor could instruct a student who is of the pilots choosing. An independent assessors/Examinors could assess progress and validate progress is sufficient, this person should also be of the students choosing. The aircraft should simply be one in which the instructor and student believe is suitable to instruct in. CASA should responsibility for the entirety of the theory testing. There's a conflict associated with having those responsible for teaching, scrutinizing exams, especially when performed on a 1 on 1 basis. It appears that flight schools were modeled on the requirements of WW2 flight schools and the underlying model hasn't really been questioned ever since. If I had to distill the thought processes associated with flight schools it can be distilled down to a single item its the continued use of slide rules such as the e6b calculator. Guys it's not a computer, its a calculator and not a very good one at that. I was probably in the last generation of students who learnt how to use slide rules and they were considered outdated then and I'm getting on. I'm aware of the arguments associated with their continued use and they're pretty much bullshit. I can't point to a single near miss prevented by an e6b This isn't to say that I don't like the little whizz wheels, they're fun to tool around with. But the pleasure I get in using it is the same pleasure that I get pulling a 1950 victa lawnmower out from under a house and making it roar back to life. Would I mow the lawn with it? No of course not. But the real question is would I keep it as a spare mower just in case and the answer to that is no, if I wanted a spare I'd have a spare new mower.

Does the cetane number impact startability? It's essentially the measure of combustion rate of diesel.

Diesel engines can generally run on waste oil vegetable oil or biodiesel. Biodiesel is similar in viscosity to dino diesel so is a drop in replacement in most cases. Running on pure vegetable oil generally requires a preheater and there are more issues associated with residuals. Biodiesel is created by the transesterification of vegetable oils using methanol/ethanol and a catalyst like sodium hydroxide (NaOH). Basically you mix the ingredients and the lighter alcohols replace the heavier glycerols in the vegetable oils making it less viscous and lowering the cloud and pour point. However the cloud point and pour point remain higher than traditional dino diesel which is an issues for planes. The source oils or fat is the key determinant on the cloud and pour point with tallow and solid fats creating having higher pour points than biodiesel made from oils like canola. It's also a better solvent than traditional biodiesel so it will dissolve all the deposits that have built up over the years which tend to then clog fuel filters etc. So you need to replace filters after the first tank of biodiesel. It may also dilute your engine oil if your engine relies on a burn off process to clean your particulate filter. This is because it doesn't vapourise quite as well as diesel and car manufacturers were too cheap to put a separate injector into the exhaust system and instead activate engine injectors on the exhaust stroke to initiate the particulate burn process. More biodiesel ends up on the cylinder wall and then into the sump as a result diluting the oil. It may also react with gaskets, hoses and seals which were fine with diesel, however most European and Japanse engines made since the 90s are made from materials that don't react. On the bright side it has much better lubrication properties than traditional diesel so injectors, engines, etc last longer. Testing in the US found that it was used as an additive to traditional diesel it performed better than the commercially available additives. There have been a number of studies which support this so adding biodiesel to your dino diesel is likely make your engine last longer. https://www.sciencedirect.com/science/article/pii/S1876610215013879 As for aircraft use, there have been a number of studies on various biodiesel blends or pure biodiesel fuelstock in turbine engines and it appears to be a workable solution. Economically not so much with the current price of oilseed crops. But it is significantly cheaper than hydrogen. Basically if you live in a reasonably warm climate (most of Australia), run diesels and have access to waste vege oil it's an option.

One thing that's surprising is that the power/weight ration of the Guiberson engine 0.781 kW/kg is better than the Austro Engine 0.67 kW/kg. The BSFC of the Guiberson was 232 g/kWh however I couldn't find any specific mentions of the BFSC of the Austro engine however based upon the figures in the wikipedia article are 221 g/kWh and 200 g/kWh at full power and cruise respectively if my calcs are correct. The Junkers Jumo 204 two stoke diesel operated at 211 g/kWh which is pretty good for a two stroke of WW2 vintage with a power/weight of 0.74 kW/kg. It makes you wonder how these these engines would run with a modern common rail injection system. You can compare that to 275 g/kWh for an O-235. Also remember that this is in grams with heavy fuels being about 12% denser than AVgas. ie 0.262 L/kWh for the Junker vs 0.370 L/kWh for the Lycoming. Effectively this means about a for every litre of diesel fuel you'd burn 1.4 litres of AVgas at the same power output. Food for thought especially if you run on biodiesel.

There's a good body of knowledge in this area. I was aware of the Guiberson however I didn't realise that Caterpillar redesigned the R-1820 which is interesting. Thanks for the mention of Chaz, I found a link to his plane. The drive to innovate appears to be alive and well in NZ. http://nzcivair.blogspot.com/2015/07/charlie-kennys-jodel-d-150x-zk-ccd-has.html The subaru engine appears to use a simple offset gearbox. However as many can attest reduction gearboxes are hard work. With an opposed engine like this they might have been tempted by a planetary gearbox however they're difficult to get right as well.

Does anyone know of a project to put an auto diesel in an experimental plane or if this has been done successfully anywhere. The dedicated aero engines just seem to be too expensive for the market. Whenever I see a jetfuel tanker my mind wanders and starts going down the path of wouldn't it be nice if I could just use that fuel or diesel.

I think that electronics generally will be more reliable and lower maintenance than IC vehicles. However I suspect that they won't age particularly well. By that I mean that I don't think that 30 year old teslas will ever be a thing. I've got an music amplifier that about 12 years old which I've replace a few diodes in already however it's behavior is becoming increasingly erratic. I guess I'll buy a new one. Engines made of cast chunks of metal will age better but have higher operating costs. Parts will still rust but they'll be discrete and replaceable. Electric planes might be able to meet a few niche roles like flight schools with or short intra city commute roles. However the energy density's just not there and is unlikely to ever be there unless you go the nuclear option. For those with an interest in nuclear technologies the Aircraft Nuclear Reactor experiment was a demonstration of the first MSR which is finally being considered as a reactor technology. I'm not sure if I'd like flying reactors though. Anyway which the recent political machinations the whole climate denial debacle should be in the back seat for a while while the Liberals go through grapple with the realization that they represent and don't lead the people. If you only represent a minority that's the number of seats that you'll have.

The best part of this is when the persons experience of this practice is queried.

Clear as mud without a map of radar coverage. 😉 However the AIP ENR 1.4 provides a more detailed version of the current CASA pdf extracts below. I couldn't find any reference in AIP ENR 1.4 relating to FL210 so is this a rule of thumb or a defined ceiling? So, aside from the practical limit, you could in theory, VRF to FL245 outside radar coverage zones. (If you had a definition of what the radar zones are, for example do they change during rain periods) If practicability is an issue you could of course do VFR on top at FL245 of invisibly wispy cloud. Of course you might want oxygen and a mask as canulas aren't rated at that altitude. Not saying that this is gospel however it would be nice to set a few bounds. As more zones decommissioned due to ATSB the non-radar areas may expand. One other thing that was of interest is that the boundary is regarded as existing in the less restrictive airspace.

Hi Facthunder, Would you know where this is codified/legistlated? So even if you're in class E airspace at FL 230 you must be IFR, or is the CASA document out of date? Also what happens above 60,000 are you VFR again?

Just a question about the current state of the airspace. This PDF has the following. Above FL245 outside radar coverage, Above FL180 within radar coverage Whereas Airservices provides the an airspace definition on here which states that class A is from 18000-60000 feet. I suppose the key question is which is correct and are the radar boundaries accurately defined?

I suspect that there has been a combination of causes. AVGas is a significantly higher margin product that mogas so of course even through the market it comparatively small it's worth fighting for. The engine makers didn't want to do more design and testing. The most profitable route was to keep pushing existing designs. Existing infrastructure, legally once you put leaded fuel into a system it's difficult to change. Lead poisons a range of sensors and catalysts which modern engines rely upon. This has made it easy to justify keeping two systems. Individual bias, change is hard and there is always the desire to keep doing what you've been doing. About 1 in 5 planes requires some form of modification to run mogas. The lucky owners have been vocal about ensuring that others subsidize their design choices. The hands on management appeals to me too. But I'd also like to have decent sensors to tell me when things aren't right.

It's not your imagination, 91 octane E0 Mogas has 3%-5% more BTUs/gallon than 100LL. Lead deposits from 100LL can reduce power, though. https://generalaviationnews.com/2011/03/16/10-mogas-myths/ So when you're flying into the unexpected headwind on a long water crossing you might wish that you had a tank full of mogas rather than avgas. One hypothetical that I've thought about was if you had to buy some low octane fuel when avgas wasn't available could you just retard the throttle until you were at altitude as you're effectively lowering the compression. Wouldn't it be nice to have a fully instrumented engine which could run on cheap fuel, detect knock, inject MW-50 and retard ignition as required.

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

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". 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. 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.