kasper

My co-owner of a Pou many years ago whacked the flea into a raised bank next to the runway at near takeoff speed … the undercarriage took much of the loads as it came to a stop. The front wing twisted when it struck and the main spar snapped into match stocked at every pickup point. one new undercarriage. One new centre section. One repaired engine cowl and it was up and flying again.

Yes, that is how he specs the tubes - OD and ID in your pic = 1.5mm wall 25OD mild steel and thats what works nicely in a gently failure mode when you whack the ground at speed ...

On the wing struts your OD of 20mm seems fine as they are primarily loaded in tension and it will all come down to wall thickness and how you do the ends on the legs it’s a difficult question to answer as it depends on how you are springing the leg - rubber in compression - rubber in tension - shock springs in compression and then it’s also an issue of which leg component you add the spring to because at least one of the leg members will primarily be in compression and that element greatly benefits from greater OD to reduce the risk of compression failure of a hollow tube. do some comparison design shopping. Read over the original hm290 or hm293 leg designs and consider how yours stacks up to them on design. I can report that the original main hm290 leg and struts can take a whack sufficient to destroy the wings and collapse safely to the ground with the pilot stepping out of the aftermath unscathed. The tubes failed gently absorbing a lot before failure and that is what you want in a design.

Carbon fibre rods are overkill - dead weight and $$ Just the foam formers west epoxy to the tube + a fiberglass skin (definitely very light woven fabric and not CSM) will be entirely enough. I've done similar on a set of lift struts for the sapphire (replacing a wrapped fiberglass hollow section streamline) and I did not have CNC so rough cut the sections, drilled the tube hole, assembled the stack with epoxy (glue to tube, flox filler between layers) and then used masonite templates on the ends and a sanding stick to bring to final shape before glassing and finishing. 1.5m struts gained 400g which was acceptable to me as that was pretty much exactly the weight of the hollow skin forms I removed.

Why do you expect it? For safety or for process? If for safety whose - Pilot/pax or general public? AUF/RAAus knocked on the head decades ago the link between airframe design/maintenance and risk to general public. CASA/RAAus - despite your opinion on the effectiveness of it - decry all liability for pilots/pax for the operations of the airframes - those yellow stickers are their notice of this So if it is process why expect the same process in RAAus as applies in GA when there is a stated and designed difference? I would ask - do you expect the same professionalism of all motor vehicles? Given that they are demonstrably of higher risk to the general public than RAAus aircraft the risk would demand that ... yet several states have very different compliance regimes - annual inspection after 3 yrs old, inspection only on sale of vehicle and after being tagged by police etc. and any/all maintenance and repairs on them is at the owners discretion without any documentation required ... Aviation is in my experience not really different from many aspects of mechanical repair and maintenance but comes from a history of fanatical documentation in the name of 'safety' which is actually not required for safety but may help reduce risk of failure and/or identify failure/unsafe events after the event.

Simple really. If it didn’t come out of a factory as a fully build and registered aircraft it’s an experimental airframe and engine and you really need to work from that point and not expect anything to be exactly what you might expect from a factory airframe and engine. The reality is that the value of an experimental airframe will vary wildly depending on how experimental it is be that an odd design or components not maintained in the same way and to the same life certified aircraft are. unless buyers and pilots entering RAAus aircraft start working form that point a lot of people are likely to try and MaKe experimental the same as factory. It’s not. It’s not supposed to be. And if you push to make it so you are killing off experimental as a group and returning to the 1960-1997 period where you had home built that were SO restricted that in 35 years fewer designs were allowed than my husband and I have in fingers and toes.

Given the thread drift I'll make the distinction between acts/inactions and underlying beliefs. The belief that difference based on race or nation exists is racism or xenophobia. Choosing to act or not act towards someone based on those beliefs is discrimination. If that discrimination is in the provision of goods and services in Australia then you are in the realm of unlawful discrimination. If your discrimination is not unlawful then it falls to individuals assessing your actions and expressed views that are racist or xenophobic to decide their reactions to you. On this forum one option is the ignore user function. Cheers.

Yep. The only vehicle in our fleet that was replaced early was a Ford ranger … simply because it was always our for repair/maintenance. The rest - all Japanese and Korean - have happily just run in with Std service and get to life and just keep going.

And that's the point - a single very large proposed WA zero carbon could cover all current Australian consumption and would have the ability to location and time shift the electricity to where it is currently used/consumed. There is already wind/solar as a distributed generation capacity attached directly to the existing copper network that can't store ... but there are stand alone storages being proposed to deal with parts of that. That distributed copper network connected generations/storage is growing - companies are already investing in it even without significant Govt. incentives. Everyone bags out EVs on the grounds they will "kill the network" and claim solar/non-fossil cannot provide the additional electricity to cover above the existing. Sorry but spend admittedly large numbers on major remote solar/wind generation and think about a mix of storage/time/locations shift options (water/battery/gas/chemical) and add to that smarter grid connections at houses/EV charge points and as a large system the electricity system has a good possibility to provide existing use cover + EV car conversion demand + expansion.

Well all that infrastructure out to Roma in Qld could be useful in 10 to 15 years ... In WA they are looking at mixed solar/wind covering 15,000 square kilometres and could produce up to 50 gigawatts of energy ... but putting that energy into hydrogen and ammonia to move not via wires but pipelines/trucks/trains/ships to be used as electrical generation at point of use: https://www.abc.net.au/news/2021-07-13/green-energy-hub-planned-for-south-coast-of-wa/100288734 If they did something on a smaller scale out in Roma but stored the hydrogen/ammonia to time shift generation to consumption they could recycle the wires infrastructure to feed it back into the SE Qld grid. Strangely planning to reuse infrastructure is what they want to do at Liddel in NSW - stop generating from burning coal and use the water storage to store excess generated energy from grid and time shift it back to consumption when needed - a hydro battery. The only thing I can see for certain is that electricity is going to be the major energy use form for the rest of my life and it will move to carbon neutral generation over that time. Fossil fuels are literally the dinosaur in the electricity market and the major fossil fuel companies know it and are moving to replace their fossil fuel carbon businesses.

But Turbo urea injection whilst reducing nox and co does nothing for pm10 or pm5 or co2 and can’t address the fundamental issue of using/releasing carbon from crude oil. agreed that for 99% of this forum audience their involvement in anything developmental in the wider area of alternate energy to transport will be only as a consumer of what’s being offered. but a fair fraction of this forum are very interested in the areas that are possible because they recognise that things will change and they want to know possible changes are considered.

And the query on undercarriage position is relatively variable for you - you can make up a second set of undercarriage tripods to move the wheel positions later if you find them too far back. Moving 100mm would be relatively easy with a set up you have drawn.

All else fails consider a tank in the centre section front wing behind the spar. Yes the weight for the fuel is behind the pivot so when standing still you have to lift the weight on the control stick in addition to the wing weight but as soon as the wing lift starts it disappears. you could have 10-15l up in the wing and a 5l tank further back from the current position to get your cofg movemenet reduced full to empty fuel

Possibly. But it’s still very limited range and the battery is very expensive and change is a hassle plus you’ll need 4-5 battery packs per airframe to keep it flying constantly as a trainer and it will never cover the military training syllabus - it’s not in any way aerobatic. think outside the box. An aluminium air battery has far lower cost than lithium and much greater energetic density - but it has to be recycled and not recharged. So a battery weight the alpha has could be replaced with an aluminium air battery giving near 3!times the power. If I was the military a system of plugging in for 1.5hra of aerobatic on a Good airframe that is then battery out and replace with new and have all the old ones recycled would be better than large banks of recharging highly expensive and chemically able to burn batteries. and recycling an aluminium air battery is possible - you add electricity to covert the oxidised aluminium into new aluminium and you go again. In effect the end point of the aluminium in a battery of this cycle is the baulxite you started with as ore from the ground … but already refined and sepretate from spoil.

Not sure I agree on this one ... the CofG of the aircraft is not on the CP of the front wing ... it is between the CP of the front and rear wings based on their shared load of the lift provided at touchdown/takeoff. as a rule of thumb most fleas are considered safe if their CofG is at around the 25% of combined chord of the two wings plus any gaps. That would put the CofG only just in front of the main wheel of this design. To correctly work out the furthest rear point for the CofG you need to calc the lift splits front/rear accounting for all interwing impacts on the lift achievable from the rear wing from the front wing Fortunately is generally is the case that the front wing lift becomes critical first and you work off the max lift the front wing will produce at max AofA and that sets the lift split between front/rear and you have a safe point. Never forget - the flea/tandem wing is really a canard and front wing dictates the minimum speed and the lift split and CP posiutions of the two lifting wings sets the effective angle of attack for the fuselage and from that you can work the overall CofG and the approx landing/takeoff angles that will then dictate which wheels touchdown/takeoff first. eg for the HN290 and 293 tailwheel as designed they naturally three point in the landing config because on full back stick in the hold off the fueslage adjusts with reduced rear wing lift to touch the tailwheel just before the mains - equally on takeoff the mains lift before the tailwheel as the front wing lifts them off before the rear wing can lift the tailwheel. NEVER try to 'wheel' land or 'wheel' takeoff a tailwheel flea - you will find you need to be over 70knts to get the damn tail up and you do not want to be anywhere near the ground at that speed with a short coupled undercarriage. Lots of fun with pous but I would strongly disagree that the main wheel positions for this one are at all too far aft.

Or thermal solar direct to liquid hydrocarbon fuels to use in existing IC engines. An example fo the technology spin off from research out of Zurich: https://synhelion.com/technology May be years away but if more countries around the world price carbon into hydrocarbon from crude oil this cycle becomes not only possible but price competitive. And I wager that is will always be easier to fill an airliner with liquid fuel to burn in existing engines than it will be to get all the infrastructure and equipment change required to move over to battery/other stored electric forms of running an airliner on electric alone - the energy density of hydrocarbon liquid fuels is just SO high it is not funny.

I can only say what I've experienced. T88 out performs bote cote when I have used it.

Nothing new there. I extend flaps on downwind and then on base and final. I cannot recall ever extending them during a turn.

My concerns with asymetric flap are not on extension - I expect to see/feel any asymmetry as I extend the flap. My plans have always been - as were taught to me in AUF training last century - was to talk myself through the flap extension and positively confirm to myself both extension and pitch change as expected with being prepared to stop extension and retract if not happy - then go around and do flapless. As flap extension always starts at circuit height I know if things are starting to go wrong with flaps I have height and time to deal. My concerns are for either flap retraction in part or asymmetric once on final. My experience with an LSA55 Jab flap handle popping out in the early days scared the bejeezus out of me as it was uncommanded, unexpected and unpleasant. That was WAY back in the Jab airframes history when the flap detents were just fibreglass and not even an ali plate ... the holes wore and out popped the flap handle with a spectacular drop from the air. All I can say is if I was unexpectedly on final with asymetric flap retraction I am kicking in any and all rudder and dealing with either an untidy arrival (if very late final) or removing flap and powering up to go around.

The website is a pretty horrid mess that RAAus know they need to fix. I'll start sounding like a broken record. Call RAAus and ask for membership and they can do it over the phone. No doctor cert required and you can get on with building.

Sorry all but you are out of date with inspections and out of touch with 95.10 which is different. both 55 and 10 have 4 inspections since the last tech manual. 10 does not have the same permits and test flying. It’s just registered and away you go. and whilst an inspection is standard L4 any L2 can be specifically authorised to do an inspection- that can be for. A specific single airframe or all of a type of aircraft depending on what the tech manager is feeling like allowing and what is asked for. basic rule - talk to tech office and all the mish mash of out of date and cross type discussions disappear

But let’s be a little more reflective. spar varnish has been used for decades before epoxy came along and when not exposed to uv it’s stable for 10-15 years. Polyurethane is similar. Inside a uv reflective fabric wing it’s fine. people are not used to recovering fabric wings every 10years or so and maybe should - you still want to go in and take a look. I’m. Up to my third look inside the sapphires wing to keep track of the structure. an experimental single seat airframe is just that experimental. I’m happy if my airframes get 10 years use before I review/recover/scrap or retire them and can we speak about the elephant in the room - old age. Most builders are not spring chickens. My flea airframes and the single seat trike will be owned and flown by me only. I designed them. I fly them and they have no value as aircraft just as residual parts. If I started a new airframe today it will take me five years to finish it and I will have 15 years of flying it before my flying life becomes spectator only. if Duncan is building a personal one off flea type and is near 70 yo it’s unlikely he will be doing a first life refurb on the airframe and saving $2k on epoxy looks a reasonable choice people can’t understand how my airframes cost so little … second hand expensive bits and low cost new bits with risk all on me. Simples.

Simple and clear. memebr liability is limited under the corporate structure to our investments in the company plus $1 is liquidation. so any law suit is basically limited to the value of the building we own in Canberra as it costs more than $1 for a liquidator to send you a letter of demand for the $1 you are liable for. director liability is their problem. It’s a company they that is how it’s been run for the past few years so leave it to them to have cover.

Jack you are talking apples and pears. Either you want a certified by the government regime as a necessary step to have public safety OR you have recreational flying with lower standards as the risk to the public is limited and the risks from a societal perspective is acceptable. if you want an audit of LSA self certification with an “out” for the manufacturer because the govt said it’s ok the you are scrapping any and everything the raaus and it’s predecessor orgs have fought for for the past 40yrs. sorry but if you want fully certified aircraft go to GA. Accept the costs and accept the restrictions. LSA was never intended to be the same as certified GA and if you thought it was you were very misled in that belief. LSA is trust your manufacturer not trust your government- if your manufacturer disappears you become an orphan airframe. If your manufacturer told fibs you live with the consequences of those fibs and go back to the importer/manufacturer.

But you are missing the whole point of LSA manufacturing - its self certification by manufacturers of not just compliance with the design standard for the type but also self certification of the individual airframes they manufacture and maintain. So- IF a manufacturer tells fibs about the performance characteristics of the aircraft in the design certifications and is caught out ALL airframes get grounded. IF a manufacturer tells fibs about an individual airframe meeting the design standard then THAT airframe gets grounded. My understanding was that the initial concerns (from wherever raised) were that the spin characteristics may not meet the performance characteristics of the design standard do it was potentially a ALL airframes get grounded. However, when they did a check of the spin characteristics they also did a check on the airframe they were looking at and found additional certifications concerns being POH errors AND an unmodified from factory airframe that was SIGNIFICANTLY over the empty weight it was certified by the manufacturer to be and that weight made the use of the POH to determine CofG made the actual safety margin minuscule thin AND operators were likely to exceed legal MTOW based on the invalid empty weight Overall if faced by that - even if you were dobbed in my RAAus or provided with a strong steer to look in that direction by them the onus and liability for the errors (and the losses to the manufacturer or importer resulting from the errors) sits squarely with the manufacturer. Very simple really - the errors were made by the manufacturer and have to rectified by them to get the fleet flying. Bristells may be able to fly again ... but if I were an owner with an empty weight plane that is higher than I was told at purchase I would be getting my lawyers to sue the importer/manufacturer ...