onetrack

......question to the group. "Why do the aliens found on the crashed Roswell UFO, look so much like Turbo?" The revelation brought out mixed levels of concern amongst the others. Could Turbo have come from an alien family, and perhaps even just be a humanoid, not a genuine homo sapiens?

The thought brought disquiet upon many of the assembled gathering, and one of the group spoke up, "I'd heard before, that Turbo had the ability to put a level of terrifying fear into anyone who crossed him, but this revelation is.......

There's too much emphasis placed on bore condition. You can have all kinds of patterns, wear, gouges, scores and problems with the bore - and the engine will still run reasonably well. But the major weakness of IC engines is poppet valves.

95% of your engines problems will come back to valve sealing and seating and valve head condition. Valves are the most heavily worked part of any IC engine.

Sleeve valves and porting really are a much more durable arrangement, but the drive mechanism and clearances are critical areas, and they can't handle high RPM's. In tests of the early sleeve valve car engines in the late 1920's, the sleeve valve engines were still reliable, and still producing 99% of their power output after 80,000-100,000 miles - unlike their poppet valve cousins, which were suffering serious power losses and valve sealing problems, in as little as 40,000 miles.

I would have liked to have seen the rotary valve head become more developed and widespread, but inertia and lack of funding, often stopped many good ideas. The Deane Rotary Valve, an extremely promising Australian invention by three Aussie engineers, was proven to work, and be exceptionally efficient and reliable, when tested on a motorcycle engine - but it failed to gain financial backing, and fell by the wayside, as with many good design ideas.

That's a bearly believable photo.

Well, it appears that Wisk Aero is gradually closing in on the pilotless, eVTOL, air taxi dream. As a fully-owned subsidiary of Boeing, they have a fraction more street cred than the usual Internet/YooToob startups.

However, even Wisk won't be drawn into a specific date when their product is finally guaranteed to be safe, and receives certification - but they coyly state they hope that event is, "before the end of this decade".

Discover Wisk's Self-Flying eVTOL Air Taxi

WISK.AERO

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Our self-flying, eVTOL air taxi will set the standard for the Advanced Air Mobility Industry and transform the future of mobility.

Wisk Partners with Airservices Australia | Wisk

WISK.AERO

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Wisk Partners with Airservices Australia to Incorporate Autonomous Air Taxi Network into National Airspace.

Leaf springs are normally heat-treated in the following manner, which produces the toughness needed.

They are heated to 780°C, then quenched in an oil bath. A brine bath can also be used, instead of oil - although oil is generally regarded as superior. This process hardens the steel.

Then the hardened leaf or leaves are placed in a furnace, and evenly heated to 380°C, and then allowed to cool naturally. This is called "tempering", and it lowers the hardness and toughens the steel.

The leaf or leaves need to be restrained in a jig when being hardened and tempered, as they will normally buckle or curl out of the desired shape.

Try this spring manufacturer, they say they'll manufacture custom springs.

Did anyone see how close he came to hitting the wall with the wing?  I reckon there's only a few centimetres between the wall and the wingtip, just before he clobbered it with the tail.

I like this part of the description - "The control is done by means of a radio control on a desk in front of the pilot (on the prototype)"

Now, where have we seen this dodgy style of control setup before? 😞

Red, the placard is pretty fine print for my aging eyes - but the gist of it is, he's using 62cc Zenoah R/C engines (model G620PU-1) running Walbro carburettors, which are each driving the props through a RADNE centrifugal clutch and a gearbox with a 45mm primary pulley and a 180mm secondary pully, using poly V-belts. The engines use servomotors on the carbies for control.

He says the engines produce "6 CV" ("Cheval-vapeur", the French word for HP) each - but that's at odds with Zenoahs website, which says the engine gross HP is 5.46. The French bloke also claims 8000RPM for his Zenoah engines, yet Zenoah say the maximum output is "around 7600RPM". He's really winding those little Zenoahs out!

The Frenchman claims the engines produce 25kg of thrust each and therefore a combined total thrust of 300kgs. Not too bad I suppose, if they all keep going at maximum power! He outlines that 6 props runs clockwise and 6 run anti-clockwise, so thus negating any torque issues.

He says the frame weighs less than 30kgs and the total mass is less than 100kgs - although above that, he has 105kgs, so some variation in his stats there.

The engines are started by flipping the prop or by "an electric device" (type not known). All in all, not too much inherent strength or redundancy there, so I'm inclined to agree with Facthunters, "Pass"!

http://www.hobbysupplies.com.au/Zenoah Engines.HTM

Contributors commenting 31,000 times? If I've told you once, I've told you a million times!! - don't exaggerate!!  😄

A 12 rope-pull engine start, would make for an interesting takeoff experience!

The work going into non-pneumatic tyre research is quite amazing. There's actually an improved Tweel-2 now. And Michelin and GM have collaborated to produce a non-pneumatic combined tyre and wheel called Uptis, which is supposed to be getting fitted to new road-going vehicles this year. They'd better get a move on, there's not much left of 2024.

The research article below will keep you fully updated, Skippy - but be prepared to burn some midnight oil reading the entire article! You might be able to go non-pneumatic, sooner than you think!

A comprehensive review on non-pneumatic tyre research - ScienceDirect

WWW.SCIENCEDIRECT.COM

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Non-pneumatic tyre technology can overcome the safety problems of traditional pneumatic tyres. Hence, it is expected to improve driving safety signifi…

Promo for the Uptis tyre ...

MICHELIN UPTIS tyre prototype, an airless tyre | Michelin Australia

WWW.MICHELIN.COM.AU

Skippy, I guess you could always be the Tweel test pilot! 

However, the cost of the Tweels appears to be considerably more than a pneumatic tyre, a factor which might put you off!

Another point I just thought of - wouldn't the ribs act as vanes when airborne, and start the wheels spinning, thus acting as somewhat destabilising gyros? 

Are Michelin Tweels worth the upfront cost and do they last longer? - Darra Tyres, Brisbane

WWW.DARRATYRES.COM.AU

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Michelin Tweel tyres are a type of non-pneumatic tyre that consists of a rigid hub connected to a shear band, which is made of rubber and acts as the tyre's

I can't, despite going through the whole thread and all the links carefully. I've never seen a starter shaft with a pin in the end - a circlip groove and circlip, yes - but never a pin. However, I'm always open to being proved wrong, and just as you think you've seen it all, some engineer decides it has to be done differently. 

Skippy, the increased rolling resistance of the Tweel comes from the fact it flattens out more on the bottom than a conventional pneumatic tyre. I'd have to opine a radial tyre has less wall flexing resistance than the tread supports or ribs in the Tweel, which are quite stiff material.

Skippy, the lightest weight gas turbine APU I can find is the one on the Bombardier/DHC Dash-8 100 series, and it weighs 115lbs (52kgs). That's the basic twin turbine unit - add in accessories and a fuel supply, and you're probably looking at over 100kgs additional weight. Not exactly a practical proposition, I'd have to say.

Weight gain would make the addition of a small genset impractical. Even a camping genset is heavy for its size. No-one has yet been able to produce a very light generator.

The turf equipment tweels are rated for a maximum speed of 25mph (40kmh), and the tweels for ATV/UTV's are rated for a maximum speed of 50mph (80kmh). No model of tweel is approved for highway use yet.

There's a considerable increase in rolling resistance with a tweel, as compared to a pneumatic tyre. So, I'd have to opine that tweels are unsuitable for any aircraft.

The fact that the manufacturer hasn't sought to produce a tweel specifically for aircraft, tells me that the tweel is limited to off-road, low-speed vehicles only. 

"But is it safe, and does it come in more than one colour?"  😄("Bubbles" Fisher, of the ABC Inventors programme)

The BMW F650 starter is most certainly CCW rotation.

https://www.ebay.com/itm/305041039675

....."Spare Prawns", as there's always plenty of prawns to spare, whenever bull pulls into the fishing boat harbour. But bull ran into a problem when he visited a publisher. "Who the **** wrote this ****?", the publisher said, using words that he knew bull would understand, straight up.

"The punctuation is terrible!", he went on. "The paragraphs all run into one another, there's long blank bits with rows of dots - and to make it even worse, no-one would be able to follow the plot, it's so rambling, it makes......

......immediately surrounded by 72 virgins - a real surprise to bull, as in the suburb he was raised in, virgins were virtually unknown, and bull had only encountered one or two in his lifetime - whereupon he instantly understood why they were still virgins.

Still reeling from the shock of reaching for a choccy and suddenly being surrounded by virgins, bull was at a loss as to what...........

Who's to say it wasn't a mechanical failure of the nose gear?

The primary factor involved, is whether any medication affects brain function, and in what manner. There's a substantial number of medications that affect your driving/operating/piloting skills - and this information is readily available from the drug manufacturers, and the medical profession.

However, just in my personal opinion, I believe a lot of drug manufacturers, and even medical professionals often downplay the full effect of medications.

I know I've taken medications that adversely affected my skills and decision-making, and I wasn't advised fully on all the side-effects. I would hazard a guess this is because everyone is affected a little differently by various medications.

From what little I've read about ADHD medications, they're touted as a gift from God, with amazing results, and little side effects. I'd have a more reserved opinion on that angle, purely because of the power of drug manufacturers, and how they can influence even medical professionals.

I was under the impression that the main drugs used to treat ADHD are all from the amphetamine family. These drugs are commonly nicknamed "speed" drugs, simply because they stimulate brain function.

In the case of ADHD, it appears the amphetamine drugs operate on brain function in a highly beneficial manner - unlike the illegal methamphetamine drugs.

Naturally, the legal drugs are produced to a medical standard with proper QC, unlike the illegal ones.

However, the bottom line with amphetamines is, they are addictive - and the other question also remains, with regard to someone needing to take a legal prescription of amphetamine, is - what happens when they're piloting, and they forget to take their medication? 

I believe the situation as regards someone piloting with a need to medicate, to function effectively, is a question that needs to be addressed on a simple case-by-case basis, with extensive medical professional input, and not a "one case fits all" scenario. Just my .02c worth.

The very first Douglas DST, and the first Douglas aircraft with sleeper berths. But it wasn't the first aircraft with sleeper berths, that claim to fame goes to the Curtiss Condor (in 1932).