Electrical failures

[BrendAn]

1 hour ago, turboplanner said:

Where would they get ready made valves from an auto supplier for a constant power application when they are designed for intermittant power application?

Same thing applies in trucks; there are intermittent power engined trucks for metro operations and constant power engined trucks for line haul.

So you are saying no one on the planet makes valves suitable for a jabiru.  What about high performance aftermarket parts for vw. Corvairs. Motorbikes. I am sure there are plenty of valves available for air cooled engines.

 

[aro]

6 hours ago, facthunter said:

A suitable aero engine is like a good airframe. No extra weight anywhere.

When they were designed, but they are old designs now. It's instructive to see what happens when people suggest replacing the smaller engines with similar power Rotax engines. It turns out that the Rotax engines are lighter, which means a longer nose to get the correct CG, which means new spin and stability tests etc. Basically it is possible to build smaller, lighter engines with newer technology but you need to design a new airframe around them (which is exactly what we have seen with the Rotax engines).

 

6 hours ago, facthunter said:

The Wright J series motor was run flat out for 50 continuous hours in the late 20's. How many engines would meet that today

Pretty much all of them. It's interesting to read about the durability testing they do on new auto engines. They need to know if there is anything that will break, before they build a million of them.

Typical seems to be:

• 300 hours continuously at max RPM, wide open throttle
• 10-20 hours at 10% over redline, WOT
• 400 hours varying between peak torque and peak power in 5 minute cycles, WOT
• 2000 hours idling to verify oil delivery at idle speed
• Thermal cycle testing, where they chill the engine with coolant at -15C. When the engine is at -15, start it and run at peak torque, WOT until it reaches redline temperature. Then stop it, drain the hot coolant and run coolant through it at -15 until the engine is back to that temperature. Repeat 1000 times.

Every time you find way to fail an engine in development and fix it rather than have it fail in the hands of a customer is a win.

[turboplanner]

39 minutes ago, BrendAn said:

So you are saying no one on the planet makes valves suitable for a jabiru.  What about high performance aftermarket parts for vw. Corvairs. Motorbikes. I am sure there are plenty of valves available for air cooled engines.

VW, Corvair, Motor bike engines are air cooled yes, but I thought I made it clear that for a constant power application the valves you are looking for will suit constant power applications, not intermittant power applications like cars.

Edited April 24, 2023 by turboplanner

[facthunter]

  The most heat stressed valves are in side valve motors in the unsupercharged condition as the port temp is the highest with them as the combustion chamber is so inefficient. Sidevalve engines have the bluest exhaust pipes of all. Constant power equilibrium valve temp would be reached in mere minutes in any of them at high power. Large valves are the hardest to cool and they warp more. Nev

[BrendAn]

1 hour ago, turboplanner said:

VW, Corvair, Motor bike engines are air cooled yes, but I thought I made it clear that for a constant power application the valves you are looking for will suit constant power applications, not intermittant power applications like cars.

Show me the difference between constant power valves and intermittent valves. I haven't heard of this before.  

[facthunter]

ME either.  But I've lived a sheltered life.  Turbos Heat the valves up.  Nev

[kgwilson]

When it comes to weight of an engine quoted figures never seem to be the installed weight. The Rotax 912 ULS is quoted at 56.6 KG.  But you have to add the exhaust system, water pump, oil cooler, oil tank, radiator, pipework, liquid coolant and airbox (if you want to get 100HP) which takes the total to over 90KG. Air cooled engines usually have the exhaust sytem included and don't have all the additional things required for liquid cooling.

[spacesailor]

It seems  a jabiru 2.2 '' Dry weight: 62.8 kg (138 lbs) with exhaust, ''

And

Jabiru 3,3 '' Weight: 180 lbs. (81 kg.) incl. Exhaust, Carburetor, Starter Motor, Alternator & Ignition System & Accessory pack.''

are quite light in comparison .

But , mine is a ultralite 85 pound all up weight, ( 38.5554 klgms ) .

spacesailor

 

[turboplanner]

11 hours ago, BrendAn said:

Show me the difference between constant power valves and intermittent valves. I haven't heard of this before.  

There are no such terms, since the valves are specifically designed for APPLICATIONS.

You've heard of North American Driveline?

 

[turboplanner]

10 hours ago, facthunter said:

ME either.  But I've lived a sheltered life.  Turbos Heat the valves up.  Nev

Refer back to your post on G&S.

[aro]

10 hours ago, kgwilson said:

When it comes to weight of an engine quoted figures never seem to be the installed weight. The Rotax 912 ULS is quoted at 56.6 KG.  But you have to add the exhaust system, water pump, oil cooler, oil tank, radiator, pipework, liquid coolant and airbox (if you want to get 100HP) which takes the total to over 90KG. Air cooled engines usually have the exhaust sytem included and don't have all the additional things required for liquid cooling.

I found comparisons for Rotax vs O200 installed in a Kitfox. The consensus seemed to be that the Rotax was about 20kg lighter installed. I also found pictures of Cessna 150s with a STC for a Rotax engine. The Rotax was quoted as 18kg lighter, but the aircraft was fugly with the extended nose to maintain CG.

 

You can save a lot of weight running a smaller engine at higher rpm for the same power. But from the Rotax 912 to Jabiru to the PT6, new engine designs have only really been successful when they have been paired with new aircraft designs.

 

For an existing design, it's much easier to live with the limitations of the existing engine.

 

 

[Old Koreelah]

14 hours ago, aro said:

It's interesting to read about the durability testing they do on new auto engines. They need to know if there is anything that will break, before they build a million of them...

Fifteen years ago, when lots of us on the Jodel Forum were talking about installing diesel engines, one member claimed the PSA engine (used in Peugeots, Citroens, Fords, GM, etc.) had a TBO of 10,000 hours!

When challenged, he said they’d tested a batch of these diesels to destruction. The first failed at 12,700 hrs with a dropped exhaust valve.

Over 3,000 of those engines were build every day. 

[facthunter]

You'll never be able to mass produce an aero engine. The market isn't ever going to be there.  The day before your aero engine time expires it's still required to do a performance much the same as the day it entered service and have a high level of reliability as well. It's NOT like a car where you just pull over and ring someone is it?  Nev

[Ian]

15 hours ago, turboplanner said:

VW, Corvair, Motor bike engines are air cooled yes, but I thought I made it clear that for a constant power application the valves you are looking for will suit constant power applications, not intermittant power applications like cars.

The concept that auto engines can't cope with high load for extended periods is a bit of a furphy. High constant load is often significantly easier on the engine and water cooling as all car engine are now keeps the temperatures lower. All modern automotive engines are tested at full load for extended periods and also in start stop cycles where the engine is allow to get up to thermal equilibrium stopped and actively cooled to room temperature across hundreds of cycles.

One of the best examples extended high loads is https://www.torquenews.com/1084/subaru-history-how-they-set-2-world-records-and-13-international-records-set-same-time-video

Subaru drove multiple vehicles with their turbocharged engines at full throttle for 100,000km with an average speed of 223km/h

 

If you look at the failures of automotive engines in airplanes the vast majority of the failures are related to installation, cooling and gearbox reduction units. When the engine fails almost invariably the engine has been rebuilt and tweaked. These engine fail in planes because they're on off installations. If you look at marine engines such as outboards in many cases they're simply modified car power plants, for example Honda outboards pretty use the same parts as their automotive engines with things like sump modifications and special coating on the coolant channels. They went after this market because it was large enough to be worthwhile and it didn't have the liability issues of the aviation industry.

 

I have no doubt at all that given the right incentive modern car makers could product an aircraft engine with a reduction gearbox which would be significantly better than our 1950 tech air cooled clunkers in all the measures that matter such as power, weight, economy, price and reliability and this would probably be an automotive clone. Unfortunately the market returns don't justify the risks, so we're stuck with either expensive clunkers or DIY.

 

The one aero market which might make a difference is the drone market for long endurance flight. Turbine engines don't throttle well and fuel economy really makes a difference if you want multiday missions with extended loiter times.

 

 

[facthunter]

Be better for your argument if you didn't use terms like clunkers. Just because they resemble earlier motors doesn't mean they haven't progressed particularly with materials and production methods. There are virtually NO air-cooled cars these days and  even motorbikes have moved to liquid cooling in all high Power applications. Air cooling is suitable for aircraft engines  but there's a practical limit to the Power/Litre which can be reliably extracted.. Also gearboxes are complex and expensive and weigh something and redrives a source of unreliability. There's a good case for direct drive that can be made. for our types of aircraft.

  Power to weight and reliability are well in the acceptable  range by any comparison other PISTON engines available.  Nev

[turboplanner]

I have a modern engine, a Kohler 17 bhp in my John Deere ride on mower.

The Application it is used for is rotating two mowing heads into a 42 inch grass cut for about 1 to 2 hours.

That is a constant load so requires constant power output with no chance of throttling back to cool the combustion chamber.

The engine has two cylinders to do the 17 bhp job

the crank, pistons valves - all the components have been designed for a constant load without having to shut down on days over 35 degrees.

The cylinders are air cooled by a ducted drum fan on the crackshaft.

The engine so far has achieved 1,038 house so far requiring one part, a spark plug at 800 hours, otherwise nothing except oil and filters at scheduled maintanance time.

The fuel has been exclusively 98 Octane Australian standard fuel.

 

If you were looking at manufacturing an aircraft engine, this would be one of the closest, Constant Power, applications.

 

Another would be a tractor.

 

Another would be a jestski, but that has unlimited cooling water at ambient temperature albeit these days with some engines over 300 hp.

 

Another would be a snowmobile where we would look to find engines such a Bombadier and .....................Rotax.

[BrendAn]

1 hour ago, facthunter said:

Be better for your argument if you didn't use terms like clunkers. Just because they resemble earlier motors doesn't mean they haven't progressed particularly with materials and production methods. There are virtually NO air-cooled cars these days and  even motorbikes have moved to liquid cooling in all high Power applications. Air cooling is suitable for aircraft engines  but there's a practical limit to the Power/Litre which can be reliably extracted.. Also gearboxes are complex and expensive and weigh something and redrives a source of unreliability. There's a good case for direct drive that can be made. for our types of aircraft.

  Power to weight and reliability are well in the acceptable  range by any comparison other PISTON engines available.  Nev

Rotax gearboxs are very simple and reliable. 9 series rotax are light .reliable and economical. 

[Area-51]

4 hours ago, Old Koreelah said:

Fifteen years ago, when lots of us on the Jodel Forum were talking about installing diesel engines, one member claimed the PSA engine (used in Peugeots, Citroens, Fords, GM, etc.) had a TBO of 10,000 hours!

When challenged, he said they’d tested a batch of these diesels to destruction. The first failed at 12,700 hrs with a dropped exhaust valve.

Over 3,000 of those engines were build every day. 

I did 6000hrs working at a Citroen dealership in early 2000's, never experienced an engine internal failure on PSA petrol and diesel engines, but the timing belts and water pumps would fail leading to catastrophic failure. Oil leaks around the engine were also common and occasionally a welsh plug would let go on +300k unit.

 

The engines are very light for their output and very well balanced with the turbo diesel in a Belingo punching out over 300hp and a bucket load of torque from 1200rpm up to redline. All from 65kg 

Edited April 25, 2023 by Area-51

[Old Koreelah]

3 hours ago, turboplanner said:

I have a modern engine, a Kohler 17 bhp in my John Deere ride on mower…

If you were looking at manufacturing an aircraft engine, this would be one of the closest, Constant Power, applications...

On American forums there is plenty of discussion about converting these V-twins to aircraft use. 

[facthunter]

SOME of them get close but they are usually1kg wt for each. Horsepower of output They Like most are made in China. Some brands have forged and hardened steel crankshafts but you're not paying much so  why would you get much?. There's NO need to make a high tech lawnmower 17 HP isn't much but 800 hours is a good run for that sort of thing. All you often have to do is change the oil and service the aircleaner and even Briggs & Stratton... Guess where it's made, last well.  Nev

[turboplanner]

33 minutes ago, Old Koreelah said:

On American forums there is plenty of discussion about converting these V-twins to aircraft use. 

It wasn't designed to be light weight, so I wouldnt move a muscle until I had that data and the sump layout, and the carburettor feed system. My point was that you have to design the engine components to match the application, the aim being perfectly.

[facthunter]

You'll find cast cranks and nylon gears and alloy conrods, etc Hard to know where to stop on some of this stuff.. It's not quite in the HP range  WE want and may never be. Genset motor maybe? . Nev

[spacesailor]

'' It's not quite in the HP range  WE want and may never be. ''

 

Doesn't that criteria ruin an '' Exceptional '' aircraft design ?.

when an engine gives 38 HP for a weight of 85 lbs ( 38.5554 klgms ). In a single seater that gets 140 mph (  225.308 kph  vne .

 fuel consumption of 60 mpg US. (  3.85598 L p  100 klmters  ) . 

I think it's more of what most Recreational flyers WANT.

spacesailor

[Ian]

8 hours ago, facthunter said:

Be better for your argument if you didn't use terms like clunkers. Just because they resemble earlier motors doesn't mean they haven't progressed particularly with materials and production methods.

As far as I'm aware the pace of innovation has been particularly slow. The alloy used in lycoming engines castings appears not to have changed in the last 50 years and that alloy closely resembled the one used in the 1940s. Sodium filled valves are WW2 innovations.

Roller tappets or liftes are the latest innovation, this became commonplace in cars in the 1970s. Unleaded fuels are only just being approved in some Lycoming engines. Chromium or nitrided engine bores are very old technologies. I haven't seen BAM, hypereuctectic pistons, sintered pushrods or other technologies which have appearred in the last 30 years in car engines either increasing longevity, lowering costs or decreasing weight.

 

I'd interested in knowing where you think that the innovations in engine design have actually occurred. 

 

Water cooled planes were commonplace in WW2 the spitfire and the P38 were both highly efficient water cooled engines. Most of these engines also had reduction gearing.

 

 

[skippydiesel]

On 24/04/2023 at 10:23 PM, kgwilson said:

When it comes to weight of an engine quoted figures never seem to be the installed weight. The Rotax 912 ULS is quoted at 56.6 KG.  But you have to add the exhaust system, water pump, oil cooler, oil tank, radiator, pipework, liquid coolant and airbox (if you want to get 100HP) which takes the total to over 90KG. Air cooled engines usually have the exhaust sytem included and don't have all the additional things required for liquid cooling.

Comment on your  facts: 

"Air cooled engines usually have the exhaust system include...."

How can this be ? Air cooled engines usually have their exhaust systems made for the particular application - ie the weight of the installed engine will differ depending on the aircraft its fitted to.

 

"The Rotax 912 ULS is quoted at 56.6 KG.  But you have to add the exhaust system, water pump, oil cooler, oil tank, radiator, pipework, liquid coolant and airbox (if you want to get 100HP) which takes the total to over 90KG."

• The air box is certainly not required, its an optional extra. 
• Exhaust system weight, will vary with applicator just like the air cooled offerings - one point - most Rotax's will use the silencer ,unlike the air cooled mob.
• Water pump is included in the engine dry weight.
• Liquids & heat exchangers are additional (just like the air cooled engines oil coolers & plumbing))