Nostalgia

[old man emu]

16 minutes ago, skippydiesel said:

My point is

Skippy PM me please.

[turboplanner]

1 minute ago, skippydiesel said:

Shortfielder - I am also deeply effected by nostalgia - I used to have a "thing" for Mercedes W123 (1977-85) 300D & 240D's - had 7 of them at one time - something had to "give" at retirements & it was the Merc's. I could go on about the old diesel Merc's for pages but will control myself and just say - many achieved over 1 million K's, accelerated like "watching paint dry " but could maintain 160 ks all day (if so required), cornered "on rails" and just soaked up the corrugations/bumps. My best one achieved any easy 7L/100K  (this is for a near 2 tonne car). Technology way ahead of the "herd" super easy to work on/maintain and parts cheap & plentiful 

 

BUT

 

Not a patch on my Ford Ranger, great car, which wont last as long, but does things (like pull heavy trailers) that the Mercs should never be asked to do. .

 

My point is, when do you say we have stuck with the lovely old engines long enough and need to move forward, not for the sake of change but to incorporate/take on a load of improved technologies/concepts??

I thought I made the point some posts back, but I'll try to make it simpler.

The aircraft market is a tiny one compared to the Automotive market.

The variety of aircraft require a variety of engines in terms of size, mass fuel consumption, power.

So the market for each engine variant is miniscule.

Some of the improved technologies you refer to will be emission standards where, logically in the light aircraft industry these are not required.

This still leaves quite a few engine variants to be developed in miniscule quantities.

The cost of the development required is in excess of $5 billion, so amortisation of the development cost by the number of aircraft sold even over a 40 year budget doesn't return costs.

If a company knows it can't get a return on its money, it's not going to be silly enough to go broke tooling up.

With the basic tooling amortised on existing engines, the industry can achieve a performance factor which pilots can live with, at a cost which, in some cases they can afford, and other cases more upmarket aircraft which flying schools can afford.

 

 

 

 

[skippydiesel]

Turboplanner Maaaate !- most of use will know that argument , almost off by heart, doesnt change the wishful thinking one iota AND doesnt alter my observations regarding the shortcomings of LyCons or my feeling that if the USA market demanded something more in keeping with the available technologies, we would have new engine designs/concepts to select from.

[turboplanner]

15 minutes ago, skippydiesel said:

Turboplanner Maaaate !- most of use will know that argument , almost off by heart, doesnt change the wishful thinking one iota AND doesnt alter my observations regarding the shortcomings of LyCons or my feeling that if the USA market demanded something more in keeping with the available technologies, we would have new engine designs/concepts to select from.

My comment did relate to the US market, that's part of the world aviation market.

Lycoming and Continental are two different brands with many different models which might offend you, but are the backbone of GA.

[old man emu]

On 08/11/2020 at 3:59 PM, skippydiesel said:

The above is by way of illustration of my position – why do we persist with the big bore, slow revving, air cooled, unmuffled (very noisy), thirsty/polluting, aircraft donks that have served us so well but are now an anachronism???

Quite simply because what an aircraft basically needs is a stationary engine capable of producing a lot of torque within a range of low to medium revolutions. Further, by operating at low to medium revolutions, the engine can make use of air cooling better than an engine which relies on low torque and high revs to swing the same design of prop.

 

The thirstiness is due to the larger cylinder bore and piston stroke that these low revving engines usually have. Don't forget that the torque an engine can produce per expansion event is dictated by the distance between the centreline of the crankshaft and the centreline of the small rod end

 

As with everything, getting more torque out of an engine is a knife-edge dance as this video explains.

 

[skippydiesel]

OME - if Rotax and others (even Continental) can use a gear box to keep prop speed within efficient & noise limits, whats wrong with higher RPM ??

 

Oh! Turbs - my point about the USA market for aircraft engines is that it is they the Septic Tanks that are holding back the development of something better. Their addiction to big bore, thirsty, noisy donks made possible by cheap petrol, is legendary and while they have the largest slice of the market they will dictate what is available to the rest f us.

[old man emu]

No doubt a lot of big bore aircraft engines used reduction gearboxes. The use of propeller reduction gearing was very common during the height of piston engine use in aviation (the 1930s through the 1940s), with essentially all of the most powerful piston engines ever built for use in aircraft being designed to make use of reduction gearing.

 

A propeller speed reduction unit is used to reduce the output revolutions per minute (rpm) from the higher input rpm of the powerplant. This allows the use of small displacement internal combustion engines to turn aircraft propellers within an efficient speed range.  The typical maximum rpm for the propeller—2,500 to 3,000 rpm is considered optimum for an  aircraft propeller due to the need to keep the propeller tip speed below the speed of sound.

 

What you have to do is find the compromise between power and weight. Let's say that to achieve a prop speed of 2750 rpm, for a particular prop length and pitch an engine has to produce T units of torque. From the diagram posted earlier, the torque produced by an engine is the product of the pressure (force) developed by the combustion of air/fuel and the distance the centre of the connecting rod is from the centre of the crankshaft, which is basically half the size of the bore of the cylinder.

 

If you have large cylinder bores, you will have to have heavier crankshafts than an engine with smaller bores. Likewise all the other bits will have to be heavier in the big bore engine. If you make the engine lighter by using narrower bores (and lighter other bits) it will not be able to make as much torque at the same rpm as the big bore engine because the amount of force developed in combustion is less.

 

So, how do you get a smaller engine to produce the same torque? You make it rev faster. If you make it rev to, say 5500 rpm you might get the torque to rotate the prop, but the tips might be going supersonic. So you need to fit a reduction gearing to convert engine rpm to prop rpm.

[Thruster88]

3 hours ago, skippydiesel said:

OME - if Rotax and others (even Continental) can use a gear box to keep prop speed within efficient & noise limits, whats wrong with higher RPM ??

 

Oh! Turbs - my point about the USA market for aircraft engines is that it is they the Septic Tanks that are holding back the development of something better. Their addiction to big bore, thirsty, noisy donks made possible by cheap petrol, is legendary and while they have the largest slice of the market they will dictate what is available to the rest f us.

How exactly do Continental and lycoming dictate what other manufacturers can do?  Total bs. Some euro aircraft, Diamond RG50? are being fitted with the Continental CD series engines, smaller displacement geared turbo diesels. Should tick all your boxes Skippy.

[turboplanner]

I've got a good real-world example of how hard it is to design a successful engine based on size no matter how skilled you are.

 

Before the emissions era the focus on truck engine design was on lowering fuel consumption because of the Opec squeeze. Before it the Cummins 210 with loaded semi trailer could achieve about 4 mpg. After it the Cummins 14 litre in 270 hp setting in one of the fleets I'd set up was achieving 6 mpg and this became the benchmark for that power group for a while.

 

Cummins wanted to do better and they came to me with information on teir new L10, 10 litre model, 30% smaller, faster revving, but a documented semi trailer haul from San Francisco to New York at an average 10 mpg!

 

Normally when you go smaller and lighter, you lose reliability and durability, but no this design; they'd thought of everything.

 

They were using the 14 litre pistons, just a shorter stroke and the con rod at the big end and little end was the same size as the 14 litre, so very robust. They'd kept the same big cam, so this was a bullet proof engine with a hege fuel payback on Australian long distance routes. They sold me and I had no problem in getting orders from some of Australia's biggest fleets.

 

A few months later, one of my fleet customerscalled me, We'll call him Mr Short Fuse (one afternoon I'd come to his office to tell him some new Prime Movers would be late, and he'd yelled through the door "Mary, are you still there?" She said "Yes, Short"

He said "Well go home so I can tell this bastard what I really think of him")

 

He told me three of his new Prime Movers were at Cummins having new pistons fitted, and what was I going to do about it.

 

I phoned Cummins and arranged to come over the the service office later that day.

 

When I got there, I should have realised the significance of about ten pallets stacked a metre high with pistons, but I'd never had a piston problem on a Cummins, so just thought they were rebuild scrap.

 

When I walked in the girl on reception jumped up and said "We've been expecting you and walked me straight into the Board Room, telling me she'd be back with a coffee. On the way I'd noticed an office full of suits; unusual in a Service facility, but still didn't register.

 

A few minutes later the eight walked in after, as I later found out working out a strategy to shut me up, and sat down rather nervously.

 

The General manager opened by saying perhaps an Engineer (my friend) could start by giving us the current status on the L10.

 

He started with "At the present time we have 120 issues with the L10. I didn't hear the "but we've got fixes for most of them" I was just visualising my next meeting with Short Fuse.

 

For the next couple of hours we went through issues and actions and who was going to do what and they stood behind every customer and we eventually got out of the soup, but the L10 was never to winner it's designers thought it would be.

 

That's what can happen to a concept.

 

Cummins Diesel last year spent $1 billion dollars on research, development and engineering expenses and they have a lot less engine variants that the General Aviation industry, and huge annual sales by comparison.

 

 

 

 

 

 

[skippydiesel]

4 hours ago, Thruster88 said:

How exactly do Continental and lycoming dictate what other manufacturers can do?  Total bs. Some euro aircraft, Diamond RG50? are being fitted with the Continental CD series engines, smaller displacement geared turbo diesels. Should tick all your boxes Skippy.

Its not that Continetal or Ford or Cummins or Lycombing or whomsoever makes engines is dictating what we purchase - they, the manufacturers, are responding to what they would see as market forces. Market forces are predominantly what the consumer demands. There are other factors/pressures - government legislation for pollution & fuel efficiency being a significant one.

 

The good old USA is the largest single market for small aircraft (probably for any aircraft). If the USA customer says he/she want big bore slow revving engines, that what the suppliers will deliver or go bust.

Most (all) of the engine suppliers are also based in the USA compounding he problem.

So the rest of the small aircraft world must pretty well fall into line.

 

Aircraft manufactures are desperate to to sell in the USA (the biggest market) so they put USA engines in their aircraft.

 

This is just basic supply & demand - the biggest demand (USA) gets all the attention from the suppliers (also USA) and the rest of us have no real choice other than to fall into line

 

We wont get light weight, fuel efficient, quiet aircraft engines any time soon (Rotax at the very small end, being the exception). I suspect electric motors will probably be the next change, that even the ultra nationalist Americans will have to accept (reluctantly).

[old man emu]

14 minutes ago, skippydiesel said:

The good old USA is the largest single market for small aircraft (probably for any aircraft). If the USA customer says he/she want big bore slow revving engines, that what the suppliers will deliver

Have a think about that recurring question we get here about buying an airplane. You can tell from the way these questions are framed that the buyers really don't know much about the engines in the  airplanes they are looking to buy. They are like people who go to by a car, not really being knowledgeable about the engine and transmission, but knowing a great deal about the trim options and accessories. 

 

So how many people buy an aircraft based on engine displacement and torque development?

[turboplanner]

 

10 hours ago, old man emu said:

Have a think about that recurring question we get here about buying an airplane. You can tell from the way these questions are framed that the buyers really don't know much about the engines in the  airplanes they are looking to buy. They are like people who go to by a car, not really being knowledgeable about the engine and transmission, but knowing a great deal about the trim options and accessories. 

 

So how many people buy an aircraft based on engine displacement and torque development?

Probably none.

 

Aircraft purchases are, or should be decided on Application.

Truck purhases also are decided on Application

Some cars, like those which may have to tow, or others which may need to be fast are decided on application, but the rest have enough overlap that they are pretty much a lifestyle choice.

 

If you're aircraft Application is flying for pleasure and that decides a Cessna Skyhawk, you're going to get whatever engine comes in it.

 

If you're doing long range touring or charter and that application decides a Cessna Caravan, you're going to get whatever engine comes in it.

 

 

 

[skippydiesel]

10 hours ago, old man emu said:

Have a think about that recurring question we get here about buying an airplane. You can tell from the way these questions are framed that the buyers really don't know much about the engines in the  airplanes they are looking to buy. They are like people who go to by a car, not really being knowledgeable about the engine and transmission, but knowing a great deal about the trim options and accessories. 

 

So how many people buy an aircraft based on engine displacement and torque development?

Good point OMU -

I would suggest though that the vehicle purchaser will have some duties in mind when making a selection - sporty (mid life crisis), econamy (green), towing ability (grey nomad), commuter (best price) all of which have a direct relationship with the engines ability to deliver those sort of outcomes. 

Aircraft are something else - same engine in different airframes can have very different performance characteristics. As an illustration - A Rotax 912 ULS in a Foxbat will struggle to cruise at 100 knots but probably stall in the mid twenties. The same engine in a Sonerai 2 can cruise at 160 knots, stall still pretty good, in the high thirties,.

My point is, the potential purchaser of an aircraft might rightly focus on flight characteristics, befor taking much interest in the motivating system.

 

[Wirraway]

1 hour ago, skippydiesel said:

 

My point is, the potential purchaser of an aircraft might rightly focus on flight characteristics, befor taking much interest in the motivating system.

 

Did someone mention Jabiru????

Yes I know,.....hat, coat, door.......

[skippydiesel]

4 hours ago, Wirraway said:

Did someone mention Jabiru????

Yes I know,.....hat, coat, door.......

I tried to find an auto comment to agree with your comment --- No not the Jab one! ..... the door!🤣

[skippydiesel]

Forum seems to be slowing down again - might have to insert a few controversial comments

[Thruster88]

34 minutes ago, skippydiesel said:

Forum seems to be slowing down again - might have to insert a few controversial comments

How about you pitch us a new engine (your design) to replace the Continental IO-550 that has powered the best selling GA aircraft for the last 20 years (cirrus sr22). We will assume your engine has the same reliability, but tell us how it will be better.  

Edited November 19, 2020 by Thruster88

[turboplanner]

14 minutes ago, Thruster88 said:

How about you pitch us a new engine (your design) to replace the Continental IO-550 that has powered the best selling GA aircraft for the last 20 years (cirrus sr22). We will assume your engine has the same reliability, but tell us how it will be better.  

Personally I can't be bothered with the rubbish all over again.

[skippydiesel]

11 hours ago, turboplanner said:

Personally I can't be bothered with the rubbish all over again.

Dear Turbs,

Cant make out if you are being provocative or dismissive. Either way I guess we can try and run with your statement - give me some time to come up with some "rubbish"

 

11 hours ago, Thruster88 said:

How about you pitch us a new engine (your design) to replace the Continental IO-550 that has powered the best selling GA aircraft for the last 20 years (cirrus sr22). We will assume your engine has the same reliability, but tell us how it will be better.  

Hi Trust,

 

Yeah! well you have me there regarding the C IO-550. I guess I would like to see a  fuel injected, boosted, Wankle type liquid cooled engine with a reduction box but that's a bit like having an erotic fantasy. 

 

As for the Cirrus ? Lots of good points and early in its history it looked like it might reinvigorate single engine GA (whole of aircraft shoot being the big selling point) but somehow it doesnt quit grab my attention (rather have a Mooney)

[Thruster88]

A little bit of nostalgia up front, some carbon fiber and lots of engineering. Viewer discretion advised,  big bore engine.

  

 

[pmccarthy]

I have been following Scrappy since episode 1. I don’t understand how he can drag race that airframe without wings. I would have expected a torque reaction that might need ailerons to manage.

[Thruster88]

25 minutes ago, pmccarthy said:

I have been following Scrappy since episode 1. I don’t understand how he can drag race that airframe without wings. I would have expected a torque reaction that might need ailerons to manage.

I was thinking the same. Dont think he gave it to much, the risk would be tipping over if it got out of shape.

[M61A1]

I reckon that big wide track undercarriage might have something to do with that.

[Student Pilot]

He must watch a lot of netflix with all those TV screens 😁

[turboplanner]

Didn’t he write the red aircraft off a couple of years ago?