LoonyBob

30 minutes ago, skippydiesel said:

I confess, as a Rotax 9 user/suporter that "all have a pretty good warm fuzzy feeling by now" BUT unfortunately this, in the absence of objective data, is just that, a warm fuzzy feeling.🙂

Er, I though most 912s and all bigger 9xxs were certified against JAR 22 or better?

Ahem. For a Certified engine, TBO refers to the core; "tops" are just an incidental.

The requirement is that any part or item of the engine should be able to run 2 inspection intervals with a flaw but no failure, that it be detected and remedied before failure. 100 hourlies, anyone? DIs?

Skip, any engine can be abused. Run a bit lean, expect to see valve troubles. Run a lot lean, kiss your pistons goodbye. Wrong sparkplug heat rating for the prevailing conditions? Run a dodgy batch of MOGAS in unusually hot conditions? Get in the habit of exceeding the 5-minute rating? Mice nibble a hole in some SCAT? https://www.aviationsafetymagazine.com/squawk_box/more-lycoming-woes/

The defining target for SRE GA is a probability of catastrophic or serious (involving fatality) accident of one per 1000,000 hours of operation for the whole aircraft. GA achieves about 1 in 810,000 last time I looked. Reacreational (worldwide) achieved ~ 1 in 435,000 over the same interval, if memory serves me

What kinds of engine failure produce a significant probability of fatality? Depends on how much IFR one flies in one's piston single; but Contacomings maintained IAW the manufacturer's schedule, by a LAME, achieve total loss of power during flight &/or engine fires at less that 1 per 1000,000 operating hours... but they have other failure modes. https://aviation.stackexchange.com/questions/21599/how-reliable-are-lycoming-and-continental-general-aviation-piston-engines

Lycoming alone have books full of SBs involving upgrades to eliminate failure modes, discovered after Certification.

Gamma radiation destroys atomic nuclii. Any structure made of atoms will be degraded and then destroyed by such radiation. It's a question of how long...

MIL-HDBK-5(G, I think) gives advice on how long austenitic stainless steels can remain structurally reliable as the cooling pipes for a reactor core... about 3~5 years, from memory.

Fission is attractive from this aspect, because it requires magnetic containment. A fragment of the Sun, contained in a magnetic bottle - what could go wrong?

As has already been mentioned, the duration of the risk and the magnitude of the potential harm makes local (earth-based) nuclear an extremely poor option. Montgomery Burns approves...

3 minutes ago, 440032 said:

LoonyBob mentioned Corby bebe.

 

Me thinks the loon might have some knowledge of the Corby (and 3 others) Star Baby design (never built) which preceded the other three John Corby designs.

SSSSSSSSSSSSSSSSSSSSSSSHHHHHHHHHHHHH! Innit luverly, though...

15 hours ago, kgwilson said:

It was a pretty lame goose. That's the only flight it ever made & that was its maximum altitude.

Banned from flight by Congress, I believe... Hughes took it off anyway. remember, this is the era of NACA being directed by Presidential decree to re-evaluate the Burnelli UB-14 and downgrade their original findings, because the major financial backer supported a political opponent of Rooseveldt...

Gearboxes? It's the execution, innit? The German review of the WW1 Hisso redrive is priceless... they were scornful of the basic design, the machining, and the housing, but grudgingly had to admit the innovative lubrication solved these problems - but THEY would never adopt such sloppy practice! (It's a NACA Report; No.17 or such...).

The Merlin & Griffon generally worked ok with reduction gears, and some round engines too... Napier used a brilliant load balancing technique on the Sabre reduction gearing, shame about the rest of the engine...

Modern gearing and modern engine design has the benefit of FEM, IF the design team knows how to use it and is not constrained by management profiteering.

51 minutes ago, facthunter said:

I know I  even moved the spark plugs off centre to get bigger valves on one engine. The block is too weak.  Nev

I'm not sure the little Pugs 9203/403) were meant to be platforms for racing; not like the awe-inspiring power and traintrack handling of the Fiat 850 Coupe! (not the Sports; that was just too much...)

BTW, if you repositioned plugs then you are a grade A mechanical masochist, and i dips me lid (backs away cautiously)...

46 minutes ago, onetrack said:

Seeing as you can convert from RAA to VH-experimental, and from VH-experimental to RAA, without major roadblocks (provided the rules are met), I would have thought the SAAA document would have been relevant to any RAA aircraft.

 

 

VH-LSA is not VH-Experimental; VH-LSA meets a Design Standard for all of its systems and structure and handling/performance, AND is maintained to a system which will not degrade that level of airworthiness. VH-Experimental may be a nuclear powered Gyrocopter made from brown paper and custard, maintained by - gasp - one of US!

ANO101:28 Homebuilts have quite a bit of airworthiness applied, and are demonstrably more airworthy per se that a nuclear powered gyroplane, even with good quality custard... and the SAAA works hard to ensure the owners of such (originally, the builder(s) have good groundings in maintenance techniques relevant to their Jodel Starlet (or Corby bebe, whatever grabs you!).

LSA-E is LSA that cannot be guaranteed to meet the specifications of the test specimen(s) that demonstrated compliance with the design standards, because the manufacture, maintenance,  or use of some aspect of the aircraft is no longer controlled to the same degree.

95:10 allows fixed-wing brown paper and custard aircraft, and I'm not sure the SAAA would welcome one...

4 hours ago, skippydiesel said:

Hmm - Is it the engine or the whole aircraft that is/not approved?

 

Me thinks its the whole of aircraft .

 

If you think about it the engine/ airframe combinator may be, sort of fixed, for a certified aircraft but when it comes to homebuilt s & experimental (not always one in the same) almost any engine (within weight limits) could be installed.

 

The above, assumes a degree of logic from the authorities. 

LOGIC??? What madness is this?

Ok, there is a sort of logic... HOSCOTS 1986 decreed that (1) there must be ultralight training for ultralight pilots, and (2) such would be a Service under the Goods & Services Act, and therefor the unsuspecting vic... students should be protected by an "acceptable" standard of aircraft safety. ANO 95:25 appeared, calling up BCAR "S" as an acceptable level of safety. However, this grandfathered Thrusters and WB Drifters with unpedigreed 2S Rotaxes and any old prop, so the powerplants were deemed to be less safe that the rest of the aircraft. To provide an acceptable level of safety for the cabbages of the suburban peasants, such aircraft were told to stay away from suburbia.

95:55 came along, which still allowed powerplants meeting no standard, then 101:55, then JAR-VLA; both of which have standards for donk & prop that are deemed to produce a predictable and low probability of failure. The cabbages are safe!

Any combination of airframe / engine / prop that does not meet such standards in any particular respect, may graduallu earn some freedom based upon a history of safe operation; the guidance for which is well established by the EAA, and picked up by the SAAA.

AFAIK, "approved" is used to mean type certified to a" non-ICAO" standard; for example, JAR-VLA. The propellor also has to be "approved", which is easy for fixed-pitch wood, difficult for everything else... The donk also has to have been maintained strictly in accordance with the manufacturer's maintenance schedule, e.g. a dual-ignition Rotax 503 that falls into a serial number block that was type certified to JAR-22, would have to have  records showing the 25-hourlies etc... from new!

Until CASA ceases to be a Body Corporate, able to sue and be sued in its own name (unique amongst ICAO signatory countries!), you won't get much more courage out of CASA than the above limited view, I suspect.

If anyone has more encouraging data, please speak up!

5 hours ago, onetrack said:

We need more Duramold construction aircraft? And here was me, thinking that Duramold had been made obsolete by carbon fibre and Kevlar?

Any wood/phenolic material cured under heat and pressure, exhibits a fatigue limit, unlike any Carbon or Boron/Epoxy. Also, it is not susceptible to post-impact fatigue, unlike etc.

Check out the TC'd "Micarta" prop for Bonanzas...

ANYway, that there Goose has a big negative carbon footprint, AND is big enough to lay a coupla acres of solar cells on top... how Green do you want???

3 hours ago, facthunter said:

I.ve worked on SP 250's It always looked like a prototype. Pipes everywhere  and based on Triumph twin dimensions/parts. Pushrod motor.   Nev

Well, the Pug original donk was pushrod, and there was room for the pipes!

Nev, Carbon, we need more of these! Class G, I think...

HeyCarbon Canary, that SiBox sure is interesting; but I'm pretty sure a gram of SiBox weighs more than a gram of lead! 😛

I thought drag coefficient was a convenient equivalence, based upon the ratio of the maximum cross-section of the body in question, to the area of a flat plate of negligible thinkness which would create the same turbulent (accelerated) wake; except in the case of an airfoil, which is irrelevant to car design...

Road vehicle power requirements are generally considered to be the sum of the fluid dynamic drag, the rolling resistance, and any effective acceleration/deceleration due to slope or pilot input. The efficiency of the powerplant per powerplant is a seperate issue.

46.5MJ/kg is the target for batteries, and we ain't there yet...

Much thanks!

On 05/02/2023 at 2:41 PM, kgwilson said:

The 140 was underpowered for sure. Even the 160HP Warrior is marginal in my opinion. The Cherokee Archer 2 (PA28-181) 180HP I flew for 20 years was about right & I could get in & out of fairly short grass fields easily though not with 3 Pax, baggage  & full tanks. The Dakota though with its O-540 235HP engine & CS prop was the best for sure but sucked about 48-52 lph of fuel

There's an Aussie Approved Flight Manual Amendment that allows a 140 to get out of a 400m grass strip at a density altitude of ~3,000ft... you have to jack it off the ground w/flaps, though!

There are also a couple of fuel coolers for MOGAS conversions, as in Strayan summer, the suction side of the fuel pump(s) can cavitate under climb conditions without it...

A 203 with an SP250 V8 goes ok...

There's a lot in the blade twist...

Errum, got a link to the Pulsar?

Hey, why not go solar-thermal? Heat 100kg of lead to say 600C, and use that to generate steam on demand... no more pesky batteries! I'm sure it could be adapted to Ultralight use, too!

Errum, a small radius LE may give a quick break-away, or it might give short-bubble separation - which in turn may result in a LE stall character, or a TE stall character, depending on what's behind it... the "original" CY, about 9.3%? T/C, has quite a small LE radius. Certainly a lot of WW1 airfoils w/tight LE radii gave bitey stalls. The Gottingen 398 (from memory) is a bit of a weirdo; it has a high maximum lift coefficient at lower Reynolds numbers, which works out quite well for the Thruster T300/500... Va, Vb, and Vc are very close!

Interestingly, if you use the NACA system to expand the ordinates of CY to 12% thick, it becomes astonishingly close to 4412. As a speed freak, I don't like 4412's pitching moment; but for a STOL aircraft, that scarcely matters.

Yes, planform, twist, and Reynold's number, dogteeth, slots, slats, VGs... HS size and position... the Jodel wing is quite a sophisticated solution to the challenges of a small runaround.

WRT section changes, yes indeed - the Jodel uses a 5-digit section for the constant chord bit, then transitions to (ignoring the aileron) what looks like Clark Y at the tip. This combination was popular for a while; there are a few gliders with the same mix (can't remember which, offhand!).

Interestingly, most such transition by straight generators, meaning the intervening airfoils are unknown/untested... there is no telling where along the span, the separation may transit from TE to LE.

Caproni made a few gliders that used "step" transitions, and seem to lose no performance as a result.

The Clark Y, and 43012, were far and away the best low Reynolds number sections tested by NACA... 43012 doesn't have the most benign stall, but as used in the Jodel D18, the upper surface fabric bulges just enough to give it a trailing edge first-stage stall, nice and easy. The Austers with 23012 (j5?) were capable of stol performance, and the stall was manageable. CY and CYH both have very progressive TE stalls...

Shortage drives up prices; simple Free Market economics...

The sun is nuclear, and it does shine all the time, just not continuously on any one bit of the earth's surface... the solutions are there, but the economic incentive is not.