Geoff_H

My personal opinion is that electric will never make it to aircraft. I see hydrogen stored cryogenically as a smaller working solution. Much lighter. All hydrogen left in the tank after flight can be expected to be lost through evaporation. I see hydrogen systems to fill tanks before and emptied after flight. Engines will require a limited amount of development. The natural gas pipelines will be able to get the hydrogen to the airports. I am worried about the flammability of hydrogen. When vented two dust particles colliding can ignites colourless gan with a flame front 10 times the velocity of natural gas. When you work on a hydrogen system you have to use brass tools to restrict spark generated.

Having started and not finished 3 projects and followed the building of many home built aircraft I can say that for me the problem is if I were to buy one that is not finished is the standard of the build. One aircraft had a twist in the fuselage that during construction required a 44gallon drum of water weight to close the fuselage. Buying an incomplete aircraft is an enormous risk. It is difficult to check dimensions etc. You could end up with a pile of junk with only an engine instruments etc able to be sold to recover costs. So to me a box of unbuilt parts has more value than a partially built aircraft. Transport costs can be large if the wings are attached. A damaged aircraft is similarly a real risk. How extensive is the damage. From my work with composite construction I know that a crack in a core maybe unable to be seen during inspection for sale or even after rebuild and the consequent costs and loss of safety are possible. Again the value to me would be the recoverable sale value of the parts. But many owners want to recover costs for their financial outlay on an unfinished project. A risk to the buyer. I sold one partially built aircraft and design that I spent several years working on as it an idea I had to make a cheap aircraft, it was just too heavy. Sold it for $1. But I learnt a lot getting the build to where I got it. Another problem I have is where to finish the project.

I want to get current again. 5years since last flight. Decided to do it first in an RA. I live in northern Sydney. Who, where and what is the best place to do some TA flying?

Out of sheer curiosity what is it that makes a fixed wing pilot a bad angry palm tree pilot?

So what do I need to do to fly a recreational aircraft? I have a ppl.

Does this mean that I can use my PPL with some Cessna 152 experience to fly a recreational aircraft?

In Australia can we have an ultralight Helicopter?

In which state is John Anderson wanting to get elected to the senate. I need to know so that I don't accidentally vote for him. I do like the size of Dick Smith's gonads!

How many incidents were not reported? I flew nearby several times. Could never understand what their radio calls were. The danger zone was placed when I was active in that part of our great land.

Everything you need to know about designing for crash survival. https://www.google.com/url?sa=t&source=web&rct=j&url=https://apps.dtic.mil/dtic/tr/fulltext/u2/a218434.pdf&ved=2ahUKEwie-cbGoObvAhUm8HMBHZtuBM4QFjACegQIBRAC&usg=AOvVaw3cFHOGbCb_0w_GSjU22SZb

I think that flat pancake landings stem from spins that are not recovered in time. Not usually taught or exercised these days.https://www.google.com/url?sa=t&source=web&rct=j&url=https://aviation-safety.net/wikibase/139874&ved=2ahUKEwj0mumb_OXvAhVw63MBHctKBi8QFjAAegQIAxAC&usg=AOvVaw2neq18dc8p_7Jc8AS4nUuk

Kevlar strerches and changes colour, hence you can see if it is damaged

Many years ago a Chipmunk VH FTA spun to the ground and killed both on board. Not long after an experimental made of Kevlar also spun into the ground. The pilot got out and walked away. The Kevlar all stretched and destroyed but the energy was absorbed by the Kevlar. When I trimmed Kevlar on a layup the Stanley knife had chips in the blade from cutting it. Very tough stuff that.

Is this failure of the window struts common? It seems like the floor is absorbing most of the impact. But the doors are not sticking closed and locking the pilot and passenger in. Must be good if a fire develops. I still would be somewhat worried at such a significant structure failure in an accident, but it seems to work for the better. Amazing! It just shows how not everything is as we would imagine.

I think that I would rather have my cabin remain enclosed. It broke at the highest loaded parts, the side window struts. I am glad all survived.

I must disagree that structure strength is more important than energy absorption of the structure upon impact. A totally rigid structure will not impart an infinite force that will break the structure. Impact absorption is more important as this reduces the energy available to cause very high stresses that will break the structure. The triangular steel frames work by the high impact absorption on deformation of the steel. The real performance indicator of a good design in a crash is the energy to deformation and in an aircraft the weight must also be a parameter. When considering theses parameters carbon fibre with Kevlar wins. Triangular steel frame design is in the same class but heavier.

If you are looking at composite aircraft and are serious about the amount of energy that your frame will absorb before you start absorbing the energy, (not so good), but want a strong light structure you would use an interwoven carbon fibre and Kevlar cloth. It costs around five to ten times that of straight glass but in Izod impact tests absorbs over twice the energy of straight glass. You will be paying for increased crash absorption. How many of us would pay for that option?

The Mooney cabin is a safety cage design

Some of the very early experimental aircraft used Kevlar in their construction. A flat spin with the pilot walking away was regarded as fantastic safety. Problem is that it is tough not strong. Some cloths use carbon fibre and Kevlar interwoven to give strength and toughness. I designed and started to build a glass aircraft with a layer of Kevlar. It was far too heavy and I abandoned the project at fuselage stage.

Have a look at the amazing survival rate of the Mooney. Tail is monocoque but cabin is steel frame with aluminium covering. This is design for minimum weight and maximum survival.

The ones that I used required heaters to keep the element at a constant temperature, around 1600deg if my memory serves me right. I agree that one for each combustion chamber would be needed to get an accurate engine situation. I don't know what the IC injection systems use. The early ones were not nearly as reliable as the later ones.

Yes. I have used them extensively for oxygen trimming controls in exhaust gas systems. They need constant recalibration, so nitrogen and part oxygen gases to frequently calibrate. The best systems automatically calibrate. I am not sure that they would be suited to aircraft, but I think that many vehicles use them.

For me parking outside was the same cost as hangaring. Hangar fees use maintenance costs added together seemed to remain constant. Maintenance costs went very high when no hangar.