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light aircraft engines

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light aircraft engines

Old 25th Nov 2021, 14:50
  #21 (permalink)  
 
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That's interesting. I'm flying an Autogyro with a rotax which has been modified to fuel injection. More power, which is nice, but needs electricity. Bigger than standard battery (lithium ion) but even so, losing the alternator means land asap. Which is not a major problem in areas with suitable landing areas, which most places are for a microlight Autogyro, but I'm giving a lot of thought to crossing significant amounts of water or forest. There is still something to be said for magneto ignition.
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Old 25th Nov 2021, 15:09
  #22 (permalink)  
 
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The automotive systems that control injector operation/timing, ignition timing, knock-sensing etc include software in what would be (in an aviation application) a safety critical branches of the fault tree. The cost of achieving and demonstrating that the branch is ALARP (let alone the 1 in 10^9 level) is prohibitive as Porsche found out with the Flugmotor. Also, as noted by others, these systems require electrical power to operate. That would necessitate re-engineering the electrical power systems on the aeroplane to the standard required for a safety-critical system because at present the electrical power systems are not designed to a "safety critical" integrity level. That's a big-ticket item in cost terms, and has further knock-ons in increased maintenance costs (as it would introduce maintenance requirements to verify the integrity of these systems is sustained).

The final question is simply one of "why would you want to?". In return for a large capital outlay and increased maintenance costs you would get a small improvement in fuel consumption and a claimed reduction in the risk of in-flight failure. In my ~250 hours of recreational flying the only engine failures I suffered were pilot-induced. None of the recreational flyers I knew had suffered any either. Don't get me wrong - thse failures happen, but non-pilot-induced ones are really rather rare.

PDR
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Old 25th Nov 2021, 15:34
  #23 (permalink)  
 
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I've directed that the plane will have to have two independent electrical systems, as the RED engine will not run without electricity. There's going to be a lot of analysis and test to demonstrate equivalent safety to simple magnetos!
This mirrors the dual electric ignition systems installed on the Rotax engines. The battery I'm advised is able to supply the engine dual ignition for 3 - 4 hours. Therefore if the alternator failed in flight you then rely wholly on the battery. The battery will have 3 hours plus of life which, in the main, will exceed the remaining fuel endurance.

Remove the screw and the end cover, and pour the water out, and let it dry. Reassemble when dry, and run engine." Yup, it worked like a charm!
A student of mine some years ago owned a garage. A customer came to him one day with a problem with the control board. she had been quoted by a main dealer in excess of Ł500 to replace it. He had recently bought a large 12" x 12" magnifying glass at a car boot sale for Ł20. When he flexed the card he quickly found a hairline crack in a solder which he quickly repaired. He charged Ł250 and she went away very happy.

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Old 25th Nov 2021, 17:43
  #24 (permalink)  
 
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The final question is simply one of "why would you want to?". In return for a large capital outlay and increased maintenance costs you would get a small improvement in fuel consumption and a claimed reduction in the risk of in-flight failure.
In my case I didn't actually want it, but I did want that particular mark of Autogyro and the previous owner had fitted the system. I decided that it was worth putting up with the disadvantages rather than revert to carbs
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Old 25th Nov 2021, 18:05
  #25 (permalink)  
 
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Could you design and manufacture a light aircraft engine that was lighter, significantly more powerful, and had better economy and reliability than traditional ones? Yes. Would the R&D/certification required make this an expensive undertaking? Undoubtedly. Is there anyone prepared to invest in something like this when ICEs are being replaced by electric systems at an increasing rate? Probably not...
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Old 25th Nov 2021, 19:04
  #26 (permalink)  
 
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Yes, the future is electric. I've owned an e-Golf for 2 years now, beautiful car, charge it at home from a domestic wall socket in the garage. Only servicing is new tyres.

I'm waiting for the Mk3 electric aircraft, that can do more than just circuits. I need to be able to carry 200kg load over 2 seats and 2.5 hours endurance. Lots of my students are over 100kg...

TOO
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Old 25th Nov 2021, 21:34
  #27 (permalink)  
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I too am very eager about electric airplanes. I did some initial research on an electric 172 a few years back. It lacked the operational practicality the investors sought. More recently, a more advanced electric airplane program (it has flown) has approached me for certification assistance. I'm eager to support this innovative effort.
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Old 26th Nov 2021, 07:35
  #28 (permalink)  
 
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Surely the point of using a compression ignition engine is that it runs without external electric power. I understand the need for some external monitoring etc but why would you then design the engine so it needs electric power to continue functioning?

Could not the failure mode be a simple standard functioning?

Years ago I thought the VW aluminum diesel engines would be a suitable base for an aero engine (The 10 cylinder) but any time I suggested it I was shouted down as "That would never work" or "They'd obviously be too heavy." Is the twelve cylinder a custom block or standard from the big saloons?
If that is privileged info I'd understand!
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Old 26th Nov 2021, 09:30
  #29 (permalink)  
 
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Magnetos are not the most reliable thing in the world so for me the argument to retain them, above all else, is churlish. The developments today are toward an all electric engine.
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Old 26th Nov 2021, 11:29
  #30 (permalink)  
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PDR1:
It is the pilot induced mistakes that I thought might be avoided by fuel injection and modern automatic engine controls. No need for the pilot to worry about mixture control or carburettor icing, for example, and a general easing of the pilot workload in stressful situations. Solutions to the reliability problem can be found, as mentioned elsewhere in this thread: eg duplicate ICU's and batteries that are big enough to supply the electrical needs for them for the whole flight if need be, etc. And, as has also been mentioned before, magnetos are themselves not free of reliability problems either.

But, from what I have read here, its the cost of certification plus the reluctance of customers to try something new that has prevented adoption of automatic engine controls, and, with electric power coming in, its likely to be an academic exercise soon any way.
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Old 26th Nov 2021, 11:39
  #31 (permalink)  
 
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Constantly needing electrical power to keep diesel engines running might look like a bad deal to some people? The beauty of the old engines is their simplicity at the cost of not being as efficient as modern more complex engines.
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Old 26th Nov 2021, 19:04
  #32 (permalink)  
 
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Originally Posted by FullWings View Post
Could you design and manufacture a light aircraft engine that was lighter, significantly more powerful, and had better economy and reliability than traditional ones? Yes. Would the R&D/certification required make this an expensive undertaking? Undoubtedly. Is there anyone prepared to invest in something like this when ICEs are being replaced by electric systems at an increasing rate? Probably not...
Nail hit on head I'd say. Porsche's timing with the PFM3200 wasn't ideal and the internet tells me the $75mil programme only produced 80 engines...

I think the advantages of electric propulsion are going to be enormous once it's really sorted.
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Old 26th Nov 2021, 19:36
  #33 (permalink)  
 
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Perfect, this leaves only the batteries to be improved.
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Old 26th Nov 2021, 21:03
  #34 (permalink)  
 
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I fly stone-age Pipers, so have to operate carb heat and mixture controls myself.

So, let's say said systems get replaced by automagic systems. For resilience, youŽd need two of each systems. YouŽd need an indication to the PIC of one system malfunctioning. Likewise of both malfunctioning. YouŽd need checklist procedures for what to do when that occurs. Not worth it. Keep it simple. My lawn-mower has run for 35 years w/o problems.

Hahaha, I'm in the software industry myself, and am responsible for hundreds of thousands of peoples assets and I know what can go wrong.
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Old 26th Nov 2021, 22:01
  #35 (permalink)  
 
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We've been having long discussions about the computer which runs the diesel RED engine being installed in the Beaver. I've directed that the plane will have to have two independent electrical systems, as the RED engine will not run without electricity. There's going to be a lot of analysis and test to demonstrate equivalent safety to simple magnetos!
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And here a salutary tale of having an engine or two reliant on wiggly amps.

https://www.aviationconsumer.com/ind...ate-1-fadec-0/
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Old 26th Nov 2021, 22:19
  #36 (permalink)  
 
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As for Lycoming or Continental, why change what works, they are pretty much bullet proof, agricultural in a way yes, but solid, I’ve seen the rare aircraft return having shed their cylinder heads, as bad as that seems it was still running and a cylinder change and top up of oil was back in service.
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Old 27th Nov 2021, 00:38
  #37 (permalink)  
 
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In traditional piston engined aircraft, the most unreliable component (and most likely cause of engine stoppage) , I would suspect by a considerable margin, is one component widely used in the fuel and engine management systems, the pilot.

I wonder if the same faulty component will be repurposed for use in future electric aircraft? If so I suspect it may also become the weak point in that technology as well.
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Old 27th Nov 2021, 00:43
  #38 (permalink)  
 
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Originally Posted by jonkster View Post
In traditional piston engined aircraft, the most unreliable component (and most likely cause of engine stoppage) , I would suspect by a considerable margin, is one component widely used in the fuel and engine management systems, the pilot.

I wonder if the same faulty component will be repurposed for use in future electric aircraft? If so I suspect it may also become the weak point in that technology as well.
Extrapolating from other requirements... just require two of them.
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Old 27th Nov 2021, 00:48
  #39 (permalink)  
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And here a salutary tale of having an engine or two reliant on wiggly amps.
Yes, this factored in the foremost of my thinking as I plot the systems for the diesel Beaver. I was involved with the testing and certification of the Lycoming powered DA-42, and these systems discussions were peripheral to that. When I flew the Theilert DA-42's this was on my mind, but they behaved fine (save for one failed turbo controller).

But the absolute requirement for electricity introduces a absoluteness of requirement which has had design compliance wiggle room up until now....

I have a computer fuel injected (Bosch) powered Polaris Ranger utility vehicle, and what a pain that system is! I wish I could convert it back to carburetted! It has never run well, and one broken wire ('cause Polaris made the engine harness too short) becomes a huge troubleshooting chore. At least Polaris' own service manual tells you that most engine problems are electric - yeah! If they'd designed their wiring better, they would need so much repairing!!! I really miss my carburetted, no computer Polaris Sportsman ATV - so what if I had to use a choke!
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Old 27th Nov 2021, 05:22
  #40 (permalink)  
 
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Compared to a carburettor, fuel injection has many more parts that 'may' fail, a carburettor is a simple thing that works fine most of the time, carb ice can be a problem, that's why the pilot is furnished with a carb heat control and is supposed to be trained in its' function and operation.
The GA industry is not flush with cash, and updating an Aero engine is not the same as Toyota or Mazda bringing out a 'new and improved' model, it is a very time and money intensive operation to 'prove' a new design is reliable and fit for purpose, that's why aero engines look like they come from the 30's and 40's , because it is so hard to change an approved design.
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