Ian

12 minutes ago, facthunter said:

There's nothing more boring than sitting at high Levels and moving as if you're stopped. You just won't get UP there either without supercharging and the OAT will require cabin heating.   Nev

I agree that it might be a little monotonous, however the image posted earlier is a NA plane climbing to 17500 pretty easily and if you're going from point A to B you might be willing to accept the monotony.

The longez service ceiling is 27000 feet which is also a naturally aspirated plane https://en.wikipedia.org/wiki/Rutan_Long-EZ

Cabin heat or being impervious to the cold might be a good idea. 

Zooming along at low levels is a lot of fun however there are risks associated with not having altitude. Altitude also gives you more options especially if you're flying over unforgiving terrain, your options increase at the square of your altitude,  Low = Increased risk.

One think that people don't appear to understand well is how altitude impacts efficiency.

You will burn the same amount of fuel regardless of your altitude if you are flying at your best L/D ratio ie best glide ratio.

Your most efficient flying speed is your best glide speed which is generally a bit slow so people fly much faster and burn lots more fuel. This best glide speed is your optimal  angle of attack at which drag is lowest.

However you best glide speed increases as your altitude increases, effectively your drag remains constant so the higher you go the shorter your trip time. However your fuel burn remains constant (ignoring climb and descent phases)

Energy = Force X Distance  (drag is constant and Distance is constant so energy remains the same)

There are a couple of flies in the ointment through, engines lose power as altitude increases limiting your maximum altitude and secondly your flutter speed Vne remains at altitude even though the air is thinner.

The other fly in the ointment is where to buy oxygen at a price at low cost. Unfortunately there doesn't appear to be many options.

49 minutes ago, skippydiesel said:

As I understand it; In Australia, recreational pilots are overwhelmingly VFR and are limited to 10,000ft ceiling.  Contemplating flight above his level or in marginal weather, is either a fun academic debate or a declaration of intent to join the IFR crowd.

There's no requirement for IFR, IFR is required for class A airspace which is

• Above FL245 outside radar coverage
• Above FL180 within radar coverage

So the opportunity to expand your horizons is simply limited by oxygen and your aircraft.

The chart below is an example of a really good resource provided to the flying community.

https://www.casa.gov.au/australian-airspace-structure

The graph shows a defiant which is NA and while the rate of climb is slowing it remain adequate up to FL180.

On 18/03/2023 at 6:47 PM, facthunter said:

Light aircraft do not have adequate de icing systems at all except from carb heat. Prop ice can make it impossible to read the instruments due to the vibration. You have to find warmer air and quickly or be sure of being able to stay clear of cloud or any chance of supercooled rain drops falling... Nev

Agree completely on the risks associated with icing, weather and the lack of effective mitigations on GA aircraft.

It's somewhat ironic that on planes where rejecting heat is often an issue that the cold is a problem in other areas.

There's a few reasons.

• Oxygen improves awareness even at lower altitude, fly to 10000 feet and take a few maths questions, you'll be surprised at how slow you become.
• Speed, efficiency and angle of attack, your most efficient speed occurs at the optimal angle of attack so you can minimise flight time and fuel burn by going high.
• weather, sometimes the weather is just bad on the way and good at either end. A bit of altitude might be all you need.
• Some people swear by the fact that oxygen makes them feel more refreshed even after a flight below 10000.
• Tailwinds.
• 

21 minutes ago, facthunter said:

Inhaling Pure O2 is not good for your health..  Nev

Like many things it depends on the dose, oxygen toxicity results from inhaling oxygen as higher partial pressures, so inhaling higher concentrations of oxygen at altitude is a good thing if the partial pressure is equivalent to sea level oxygen. 100% oxygen at sea level not so good, even worse if you're diving. U2 pilots have been doing it for decades however their problems recently have related to the bends due to higher operational tempos.

https://www.smithsonianmag.com/air-space-magazine/killer-at-70000-feet-117615369/

With the little blood oxygen sensors becoming readily available you can monitor your oxygen levels with little trouble. Even simple maths can become harder at altitude.

2 hours ago, KRviator said:

The other alternative - if you are use it routinely - is to get rid of the cylinder and use an oxygen concentrator like the Inogen G-series. Kitplanes did a writeup on their early ones in 2010 and I've been thinking about it for the RV. You can pick up a G3 for well under $2K on Gumtree.

I was never sure how the non-aviation O2 concentrators coped with altitude, for example the "Inogen One At Home" system is rated to 8000 feet". Even with an oxysaver cannula you need about 1.6L/m to maintain blood oxygen. https://www.peter2000.co.uk/aviation/oxygen2/index.html

If someone want to buy and test them that would be good 🙂

I was wondering what the best valve types and cylinder sizes for oxygen were. And is getting refills for your own cylinders available in Australia or more specifically Canberra or Sydney. The market appears to be dominated by companies only doing refills on their own cylinders. The US market cylinders have CGA-540 male fittings and the Australian market has CGA-540 female fittings.

If I bought pin indexed CGA-870 valved cylinders am I going to be able to get them filled with industrial/veterinarian oxygen?

There's an interesting article on the supply of oxygen here https://www.avweb.com/features/pelicans-perch-13getting-high-on-welders-oxygen/

Not sure that it's true but it's food for thought.

I've always thought that the options that oxygen provides would be beneficial

There are a few more articles on oxygen here

https://www.kitplanes.com/homebuilt-o2/

https://www.kitplanes.com/military-oxygen/

https://www.kitplanes.com/how-to-use-your-oxygen-system/

10 hours ago, sfGnome said:

I think what you’re missing is that the government is so incredibly competent that it chooses to appear incompetent so you won’t notice while they’re taking over the world. I know this is true because I saw a web page that said so. Do your own research, sheeple! 

I liked the quote that the the head of Coke made about some of the conspiracy theories about the introduction of new coke"

""We're not that dumb, and we're not that smart."

I spoke to a pilot the other day who fervently believed in existence of chemtrails and other Government/UN conspiracies to install overlords or something similar. 

I was a bit surprised because as a pilot he'd have an understanding of the types of infrastructure required to perform such as feat, just the the logistics alone would be incredibly difficult. As well as this being a pilot he should have a basic understanding of the weather and be able to extrapolate why some contrails will last significantly longer periods than others.

The thing that really gets me is that everyone knows that Government in general has a degree of incompetence large enough to make them the butt of many jokes, so how does this seemingly incompetent organisation run this massive secret operation hidden from the eyes of the major news organisations and only facebook or whereever they get information from etc. We all deal with CASA and know what stellar performers they are like. We also saw the head of BOM trying to rebrand the organisation in the middle of a major flood so we know that they're not savants.

Governments in general are prone to hubris, overreach and mismanagement, they're made up of average people by design, because we want the best and brightest people to be running business and research organisations.

Wikipedia maintains a list of conspiracy theories https://en.wikipedia.org/wiki/List_of_conspiracy_theories

Are views like this common in the flying community or are they the exception to the rule, I had thought that pilots, given the fact that remaining airbourne requires practitioners to be able to use critical thinking, would be less likely to side with the conspiracy theorists.

17 hours ago, facthunter said:

If a 4 engined plane lost all four engines it would glide like a 2 engined plane that lost both engines. The FAA tried to assert Sully COULD have made it back to the airport and used questionable selected criteria to make that case.  Nev

What I was alluding to is that the likelihood of losing all engines in a single birdstrike incident is far less likely. Unlike volcanic ash which is more of an environmental issue.

15 hours ago, onetrack said:

Why anyone would spend a heap of money converting the 1971 model Fire SuperTanker into a cargo aircraft is a mystery to me

There was a shortage of air freight capacity during the pandemic. My understanding was that freight was generally a secondary load type after passengers, less passengars = less freight. 

1 hour ago, Bruce Tuncks said:

We need to reduce inequality , there is research around now to show that it costs a country about 5% of gdp to maintain a level of inequality like we have now in Australia....   and there would be a lot more inequality  in Saudi Arabia than here.

The simplest way to stop inequality is to get rid of inherited wealth. Nothing is less capitalistic than inherited wealth as it involves gifting money to people based upon an accident of birth rather than the accumulation of capital based on ability.

I suspect that there would be many more programs aimed towards innovation and wealth creation if this were the case rather than programs designed to enhance the status quo.

That being said death taxes have always been unpopular.

1 hour ago, onetrack said:

with no fear of crashing, even if 1 engine fails halfway through the flight.

I have occasionally wondered if a 3 or 4 engined plane would have been forced to ditch given the same circumstances.

https://en.wikipedia.org/wiki/US_Airways_Flight_1549

Does the Stratux provide an ADS-B out option?

Having a system which doesn't provide an out is pretty limited especially if lots of people start using it.

On batteries only 250km. The 1000km is based upon some form of hydrogen cycle.

I'm not sure what bits are reality and what bits are aspirational or whether the range is calculated with or without a payload.

Hydrogen as a fuel is hard and "green" hydrogen is also also very hard. I might be wrong however I suspect that as an energy carrier it is mostly folly.

Take the case of Hydrogen production, solar and wind are intermittent, so you need to cycle/throttle your generation process, the only electrolysers which can be throttled are PEM electrolysers. However PEM electrolysers require iridium which is part of the platinum group and it one of the rarest commercially produced elements. Current production is only 7 tons a year and it is a very scarce resource. To provide a terrawatt of hydrogen generation would require about 27 years of current iridium production and the world economy would requires about 4 TW of continual electrical production. This doesn't include non-electrical energy flows which hydrogen is meant to replace. You could use other types of electrolysers however they need to be kept running which doesn't work with intermittent sources.

Hydrogen is a great fuel once you're in the air, it's weight per unit of energy is very good but production and logistics are difficult. Fossil fuel companies are hyping Hydrogen because they're the only possible suppliers from an economic perspective, but why not just use natural gas instead, it's cheap? Elon Musk chose that path for his rockets because H2 is hard and CH4 is easier and cheaper.

https://aviationweek.com/air-transport/aircraft-propulsion/can-aviation-use-liquified-natural-gas-reduce-its-carbon

But going down the Fossil fuel route still produces CO2 which is bad even though CH4 produces less.

Piranha solution will dissolve the deposits. However it will probably also continue to dissolve the entire piston 🙂

But it is good on glass.

21 hours ago, IBob said:

I think APenNameAndThat's original proposition is quite cunning, and certainly worth considering:
1. 'Turn down' hearing by inserting earplugs (hopefully without sacrificing clarity).
2. Compensate by turning up headset volume.

3. Ratio of headset sound (radio and comms talk) to external sound is now improved.

Signal to noise ratio.

The key issue is what is the attenuation profile of your favourite earplugs. If the plugs attenuation the higher frequencies more than lower ones, which they do, you're going to end up with muddy sound which mutes plosives and masks the temporal boundaries which we normally use to distinguish speech. Plosives have a lot of higher pitched sounds. This may not matter much if you already have some hearing loss.

This is one of the reasons why, as you get old, and your ability to hear higher pitched sound diminishes, conversations in noisy places with lots of hard surfaces become increasingly more difficult.

I'd be tempted to just buy noise cancelling headphones with good physical attenuation as well as active attenuation. It's hard to get published figures on these though I love to see test results so it was easier to make some value based choices.

On 28/12/2022 at 9:53 PM, Paul davenport said:

Yep agree with you rogerc except the bit about running at high power settings for long times.

The old Subaru engines appears to be able to cope with extended high revs at max power https://www.torquenews.com/1084/subaru-history-how-they-set-2-world-records-and-13-international-records-set-same-time-video

Of course this is only about 500 hours.

1 hour ago, RFguy said:

somewhere around there is a nice FAA chart of likelihood of icing versus temperature and humidity

P1xT1/V1 = P2xT2/V2, Bernoulli and heat of evaporation, explains why icing occurs. But the reason why carbs are significantly more prone to icing than throttle bodies or fuel injection is due to the design of carburettors.

Engines with carburettor have a butterfly valve which reduces airflow and thus reduces power and  creating lower pressure behind the valve.

In addition carburettors utilise the venturi effect to suck fuel into the airstream, further lowering the pressure and associated temperature. https://en.wikipedia.org/wiki/Bernoulli's_principle

Then on top of this is the cooling effect of fuel being vapourised.

This all adds up to a significant cooling of the air below freezing, causing moisture in the air to become supercooled which freezes directly on contact with the internal carb structure.

While some carburettor planes are less likely to suffer from carb ice than others, the fundamental design of carburettors makes them susceptible to icing and because fuel delivery can be impacted by small changes in the airflow cause by icing significant power loss can occur without much ice accumulating.

This is a flaw of carburettors and it mitigated effectively by carb heat. Going without carb heat or equivalent poses a risk in some weather conditions. 

There's a good story on induction heating being required on Ellison throttle bodies in ideal icing conditions over New Guinea which is probably about as bad as it gets.   https://josteve.typepad.com/blog/2010/04/the-puffin-has-landedin-oz.html 

The stabilised earth  floor is starting to look attractive.

13 hours ago, Geoff_H said:

I didn't think that I had monocular vision but the optometrist told me I do.  I hate glasses and have better vision than when I did use glasses then contacts.  The monocular vision is more of a problem during the class 2 medical.  

The lowest cost path to getting your licence is getting your eyes tested and getting glasses. Otherwise you'll be spending lots of time booking specialist appointments and arguing the merits of your case.

At the end of which they may recommend that you get glasses which correct your vision sufficiently.

On 25/11/2022 at 8:08 AM, Geoff_H said:

My optometrist, unhappy that I am not buying glasses anymore, said that I could not catch a ball with this vision. 

You don't have monocular vision. You should get glasses which correct your vision, and you'll have a flies with glasses on your licence. And you optometrist will enjoy your company again. Probably cheaper and easier than the alternative route.   

1 hour ago, Bruce Tuncks said:

I reckon though that a shed-type hangar of about 12m span would be cheapest when the doors etc were all added in.

Yes you're probably right. Curved beams in wood are cheaps than steel generally, I just like the whole ww2 vintage feeling of the arched hangars. 

Sliding doors start off nice and over the years become more difficult and you arms need to become stronger.

1 hour ago, facthunter said:

Overlaps without enough fall are risky from the leaking point of view in strong winds. Condensation is also inconvenient when it stains your costly paint job. or rusts valuable engine and electrical parts. A hangar HAS to be quite well done including wind related strength and fire. Nev

Yes, you're right, however an arch type hangar, width 20m with 3x8m sheets spanning the roof, with glulam beams ~400mm deep providing support, and cross bracing using standard strapping would meet Australian standards in terms of strength and wind loads. Cyclonic wind loads or public shelter requirements might need thicker sheeting or plate attachments but that's out of scope for my needs.

The centre section is spanned by a single sheet and the fall at the point of the join is well beyond minimal fall to ensure that leaks don't occur. Condensation is reduced by a vapour barrier like sarking and is the recommended way to mitigate this, birds in hangars seem to be more problematic for paintwork in practice.

Solid timber maintains its strength for longer under high heat loads, however it does burn of course. The main risk from a durability perspective is probably termites and from a construction perspective finding someone willing to build the arches cost effectively to spec.

An arch is more efficient in terms of steel used than a box and you can use dish drains rather than guttering so it's a bit of swings and roundabouts.

You can go pretty large with simple wooden arch frames.

https://internationalforestindustries.com/2019/04/17/nz-massive-new-hangar-wood/

On 10/12/2022 at 5:06 PM, facthunter said:

Expansion is a problem with single sheen and curved.  Nev

Is would be simpler with multiple sheets not a single sheet, using three sheets, ie 2 sides and a top sheet over the crest gives sufficient expansion on GA hangar sizes. On a larger project you'd be putting in expansion joints when you exceed 23m spans.

On 10/12/2022 at 5:21 PM, facthunter said:

The continuous sheet wants to lift of the structure when it gets hot in the sun.  Nev

Even with a single sheet.On a 20m span you get about 12mm of expansion with a 50C temperature change which is reasonable. So about 6mm on each side which should be manageable using standard attachments and tolerances.

3 minutes ago, facthunter said:

Expansion is a problem with single sheen and curved.  Nev

Not sure what you meant. Arches extend easily in along their axis, changing the span is difficult, however gabled rooves suffer from the same limitation. Is it likely that you're going to buy the neighbouring block and extend, and have a neighbour willing to sell? Is it simpler to just buy a bigger site?