Area-51

If scuba divers pee in their wetsuits, then it must be ok to pee in a flight suit!! 🤷🏼‍♂️ I don't have a flight suit; somebody that does will have to take one for the team and report back with results.

The other bird is registered VH-POO and mostly flies around canberra.

Runway is fine; 8 goats were run along it to smooth it out just a few hours earlier.

No his head is safe; the helmet is the roll bar. Very solid.

not sure if this one was posted... its very advanced!

The Sonex is a terrific aircraft just as it is with just 80hp, and does a few things better than the Europa. The weak point is the canopy frame flex fatigue failure and thin plexiglass thickness.

Wing root flares are not what many might think when it comes to flight performance gains. In straight and level AoA trajectory there are no substantial gains between the same aircraft using or not using wing root flares. This should not be confused by the seperate criteria and affects of wing root to fuselage corner fillet. Although the flare does incorporate the corner fillet aspect they both provide alternate results. For the speeds of most ultralights corner fillets of 50mm radius provide a better reduction of interference drag than those of 10mm. For wing root flares 100mm to 150mm radius corner fillets at the flare provide much better results than 50mm fillets; there is no advantage going larger than this other than to cause discussion. The two images above present this aspect of straight and level AoA flight (3.25deg incidence included). Both models return nominally equal Drag and Lift results within this flight mode regardless of air speed. Where the wing root flare excels is within the intermediate AoA flight modes where the wing is transitioning through 4deg to 6deg AoA. Within this narrow band the flare reduces vortex turbulence generated by the contrast of upper and lower transient flow rejoining by channeling the free stream toward a more gradual reunification. This reduction in Drag on the aerodynamic example pictured, at 100kt and 6deg AoA, the flared wing provides about 65kg more Lift and 20% less Drag compared to the non flared model. This would occur during a situation such as a rate one turn, or, raised nose attitude cruise due to heavier AUW, or, glide approach. This aspect described above is presented in the two images below, the blue areas represent turbulent slower velocity air, the red represents higher velocity air, green represents free stream velocity of 100kt. Outside of this narrow performance band the wing root flare provides no advantage or hinderance. So to conclude wing root flares are most effective during bank turns. They allow for tighter turns to be achieved over their non flared counterpart, and a more efficient cruise at higher AUW. "No lawnmowers were harmed during these scientific experiments."

Yes, it's quite a common affliction. Generally starts to cure all by itself some stage after the 55th year. On rare occasions as late as 76th year. Medical profession has no idea at all what causes either onset of the affliction or miraculous sudden remission. Much speculation has been placed upon the affliction during the industrial revolution and beyond with punters waging both small and extremely large bets over the late 19th century through to present day with only a short interruption during the recent period extending late 2019 to early 2023. Governments around the world have no answer as to the cause of this interruption and strongly deny any involvement citing the scientific white paper "dust levels upon bovine dung" as the only possible mitigating evidence and proof of cause and effect. Recent meetings of global leaders has delivered a "moving forward" strategy to once and for all determine the cause of the affliction. Being haled by all global leaders as "pure genius" the new "never tried before" strategy will create a pathway through the uncertainty to where the Afflicted and Non-Afflicted (all others) will be isolated from one another on a permanent basis in an exciting and generous attempt to prevent and eradicate the occurrence of Affliction Remission. The "Work Much Better" campaign will begin rolling out in harmony across the world this Friday with both Afflicted and Non-Afflicted requested to submit themselves for screening and collation activities. Those presenting themselves early, prior to suggestive actions, will be be presented a free case of chocolate milk.

Sunday. Feeling inspired to level the field again 🤷🏼‍♂️

Looks like its seen some miles, and it is a fully self contained powerhouse. Just turn it on its side, lash it onto the hills hoist air frame and bolt an industrial pedestal fan blade to the crankshaft and you are pure Holbrook vintage; straight into the barbed wire! 🤩 Time to live!!!

Agree, but the earth is still rotating

It rotates; eventually.

A couple of more sessions on the 914 and some more answers emerging from the mystery of early lifter failure. After frustrating and inaccurate results from the trusted mitutoyo kit some specific sized gauges were turned up and mic'd on the lathe and finished off with a polish. The one on the right measures for flogged out lifter bores upon tear down and will go in the Special Tools draw. The one on the left is matched to the 914's current lifter bore diameter; it measures 0.8748". The diameter on all the hydraulic lifters is 0.8745"; that's a 0.00015" operating clearance. I think somebody at the factory has maybe pushed '0' on the CAM console one too many times? Either way 0.00015" wall clearance on a hydraulic lifter is pretty tight. All the more reason to warm up that engine before WOT or suffer early valve train failure. I would expect this issue has been sufficiently rectified since the engine's 1998 production date; 0.0005" to 0.0015" being the standard wall clearance. Not sure what Rotax actually specify. upon writing I have just heard from someone that rebuilt two pre 1998 9XX engines that upon tear down both engines had chronically hammered grooved lifter faces. So maybe this was an endemic production issue. Glad to of identified a source of and reached a conclusion on this one.

Thanks for lifter deets there Kyle. Much appreciated. Lapping in lifters to the camshaft is a lost art and there is the science as well that comes from years of experience working with metal and machines; so there is no break in period required as it is done by hand prior. The camshaft lobes have been scrutinised and wear marks present all lifters operating slightly off center as required. I have had more time to sit and nut this situation out and go through the many possibilities. Firstly the worst presenting lifter was put in the lathe and polished up with cotton and brasso, then the contact face was lightly lapped and then brasso polished. The lifter surface was pretty slippery afterwards. Then the diameter was mic'd again 0.8745", unchanged. The face was checked with a dial gauge, 0.004" convex and 0.00025" deep trough mark from not spinning. Then the lifter was placed into the cleaned bore lubricated with diesel. While sliding down the fit was somewhat tight until fully in place where it could rotate freely. The rotation of the lifter operation was checked. It rotated until the trough aligned with the lobe crown; so that lifter as is is cactus. I am not at all happy with the tightness of the lifter when it reaches the top of it's stroke, which may be a mitigating cause toward not spinning. Will have to mic up all the other bores and compare. However at this stage I am leaning toward operator error as the cause of this abnormal early lifter failure. Allowing the engine to sufficiently heat stabilse before going WOT into the sky is so important; reason being. These lifters are operating in a chunk of alloy that takes a whole lot longer to reach operating temperature than the lifter does. And the lifter is clearly operating at a very minimal bore clearance. If the lifter heats up and grows before the crankcase has had sufficient time to equalise then this clearance is again reduced. And what can be expected to happen when sustained WOT is selected too early? Lifters that don't spin is one answer of many. Which is what I think has happened here. So a new set of lifters will go in and the if not sufficient an extra 0.0005" bore clearance at the unused section of the upper bore will be dialled in. To be honest these lifter bores should be interference sleeved with bronze or EN31, but I get that the crankcase only has to reach the TBO. May opt to have this done while the crankcase is apart. Regarding lifter leak down rates. I have read a few posts about lifters leaking down overnight. This is not an issue so long as the lifter operates correctly while the engine is running. The concern is greater if the lifter does not leak down. Leak down rates vary greatly. The standard automotive (rotax) lifter can have a leak down rate of anywhere between 80-160 seconds, and this is why some engines idle rougher than others. Higher precision lighter weighted lifters can have a leak down as low as 20 seconds balanced across all lifters; while operating at high rpm the lifter stays pumped up; while at low rpm idle the lifter leaks down reducing valve lift and duration resulting in a smoother idle and easier startups because the high speed valve timing has been altered to a more sedate manner. The lighter weighted competition lifters will also help reduce valve float as well as the reduction in extraordinary level of reciprocating inertia of the valve train is affected so lighter valve springs can be implemented reducing this inertia again even more.

Cat shit...

The flywheel is the prop assembly same as the 912.

Morse Hy-Vo; quiet, less friction, less heat, less weight, less maintenance. No idea why nobody is using it.

Learning never stops. Boundaries are there for the adventurous foolish and fearless to traverse them. For everyone's safety and well being the only kind of human required to never ever attempt a traverse of a boundary is a bureaucrat. The wheel is not being reinvented, just improved.

Its called Experimental Aviation for various reasons; people manufacture solutions to known design challenges

Lucky you! Should run really nice. They are a really simply and sweet engine.

The previous owner being overly cautious and everything by the book by nature, motor would of been using what ever Rotax recommended, prob SHELL AERO SPORT+ 4 out of the 8 lifters were not rotating as required; end of story. The other 4 lifters are as good as new.

Modding out the crankcase to retain roller lifters would be a good update providing the camshaft's valve timing still functions correctly afterward. Certain that would come with other failure moments. Really not convinced by the 9XX lobe profile either, it's extremely acute with very little duration at the top, but the engines fly pretty reliably and that's what matters most to me.