Aero engines vs Auto engines

[BrendAn]

4 hours ago, danny_galaga said:

So while I'm in the camp of prefering engines designed from the get go for aircraft, still the idea is intriguing. Here's what I would do to start with for two different scenarios depending on aircraft size:

 

For big boy planes first, I would look at many years worth of Paris to Dakar rallies. I'm sure there are many categories, not just standard and modified. In the categories of standard and slightly modified (whatever that might be called) which cars were the most reliable? Not including the support trucks, which had an open class of their own at one stage. I suspect an 11 litre DAF truck engine is a bit out of the airplane league 😄

 

Don't look only at what won, but what used the least spares, and what spares were needed. That there is your most reliable, bullet proof engine most akin to an aircraft engine. Will probably be over engineered in some places, and maybe a tad weaker in others, but to me would be your best bet.

 

Talking of bullet proof, for ultralights, look no further than a late 80s Suzuki GSX1100. Around 120hp, air-cooled. Built in gear box sounds a hindrance at first thought. But you need a reduction box anyway. Pull out all the gears and lay shafts and just fit the minimal to get your prop right. The output shaft already is designed to take an absolute flogging from the chain drive. Maybe a short prop shaft and bobs your uncle! The only downside with my pick is these engines are now 30-40 years old, so careful reconditioning is key.

 

 

bmw  are good candidates because its easy to adapt a gearbox to them.

Edited Tuesday at 07:00 AM by BrendAn

[danny_galaga]

3 hours ago, BrendAn said:

bmw  are good candidates because its easy to adapt a gearbox to them.

Yes, and they look the part. But seriously, Google how bulletproof the gsx 1100 was. 

[Arron25]

10 hours ago, Blueadventures said:

7,000 is the current highest hours known to Rotax.

But how much of a 'grandfather's axe' is it?😁

Edited Tuesday at 12:22 PM by Arron25

[skippydiesel]

8 hours ago, Arron25 said:

But how much of a 'grandfather's axe' is it?😁

I don't know the answer to your question.

 

I am lead to believe that the big two (Ly/Con) are very much in the 'grandfather's axe' territory. To acheive their claimed TBO, it's not unusual for costly major "surgery", described as routine maintenance, to be conducted.😈

[danny_galaga]

10 hours ago, Arron25 said:

But how much of a 'grandfather's axe' is it?😁

Point is, they didn't blow up getting there.

[facthunter]

You don't hear about the Ones that do. I used to be Mates with Bert Flood.  Lycomings need a TOP  to get to TBO. Hardly major surgery.   Hydraulic lifters need to be checked for Bleed down Clearance. Same type of Lifter as in a 9xx Rotax I don't like Hydraulic Lifters in ANY Aircraft motor. Better with Manually adjusted tappets then you  KNOW when things are going wrong and they don't have to Pump up to be safe. Nev

[danny_galaga]

18 hours ago, facthunter said:

You don't hear about the Ones that do. I used to be Mates with Bert Flood.  Lycomings need a TOP  to get to TBO. Hardly major surgery.   Hydraulic lifters need to be checked for Bleed down Clearance. Same type of Lifter as in a 9xx Rotax I don't like Hydraulic Lifters in ANY Aircraft motor. Better with Manually adjusted tappets then you  KNOW when things are going wrong and they don't have to Pump up to be safe. Nev

Be that as it may, Rotax 912 is a very reliable engine. As is the texron range. Isn't this thread about automotive compared to aero? In this discussion, Rotax and texron are on the same side.

[facthunter]

 I though ANY reliable information might be helpful. Nev

[BrendAn]

21 hours ago, facthunter said:

You don't hear about the Ones that do. I used to be Mates with Bert Flood.  Lycomings need a TOP  to get to TBO. Hardly major surgery.   Hydraulic lifters need to be checked for Bleed down Clearance. Same type of Lifter as in a 9xx Rotax I don't like Hydraulic Lifters in ANY Aircraft motor. Better with Manually adjusted tappets then you  KNOW when things are going wrong and they don't have to Pump up to be safe. Nev

whats being mates with bert flood got to do with it.  bert flood used to fly up to a mate of mines place occasionally so i guess he is an expert too.

rotax 9 series are a fantastic reliable engine no matter how much you try to convince us they are not.

[facthunter]

He TOLD ME about a few things wrong with them. Anything made, worked on or operated by Humans IS NOT PERFECT. What a load of rubbish your Last Post IS.. Nev

Edited Thursday at 01:55 AM by facthunter
typo

[BrendAn]

14 minutes ago, facthunter said:

He TOLD ME about a few things wrong with them. Anything made, worked on or operated by Humans IS NOT PERFECT. What a load of rubbish your Last Post IS.. Nev

i agree nothing is perfect.  but 912s are pretty close. 

and it is true bert used to fly up to my friend's place occasionally.

[facthunter]

I believe you, But He used to come to Lethbridge where I instructed and I'm a good Listener and People tell me stuff, and I've ALWAYS been Interested in Motors.  Built and Modified and reconditioned LOTS of them. (and still doing it). Nev

[Moneybox]

I visited a guy repairing his plane in a hanger at Northam. It was powered by an alloy Chev V8 but suffered from a belly landing when the gear wouldn't deploy. He said the rubber band connecting to the gearbox saved the crank when the prop struck the tarmac.

 

I'm surprised Honda haven't got into producing aircraft engines. I used to fit out some of their early imports like the 360cc two cyl Zot and 2 speed Civic. They've built some absolutely bullet proof little engines over the last 50 years.

Edited Thursday at 01:05 PM by Moneybox

[facthunter]

Porsche tried without success.  Nev

[danny_galaga]

I think why not is adequately covered by the simple fact that for car manufacturer that makes millions of the same thing, the tiny profit to be made from bespoke aircraft engines is just not appealing. I'm actually quite amazed (and grateful) that Rotax make the 912. How many have they made? I think I heard somewhere in the range of 50,000. In the same kind of time period they made three times as many 650cc engines for BMW, and MILLIONS of snowmobile engines, without all the headaches that come with the aviation world. 

[facthunter]

Bit like Making F 1 Motors. Many makers  have pulled out. Nev

[BrendAn]

Suzuki geo .1.3 Lt car engines are popular in gyros and some planes.

They have been used for years. 

Proven very reliable.

[Thruster88]

3 hours ago, BrendAn said:

Suzuki geo .1.3 Lt car engines are popular in gyros and some planes.

They have been used for years. 

Proven very reliable.

I seem to remember some time back a pic of a members? fixed wing aircraft destroyed following engine failure of a 1.3 suzuki. Probably not a failure of the core engine.

[BrendAn]

35 minutes ago, Thruster88 said:

I seem to remember some time back a pic of a members? fixed wing aircraft destroyed following engine failure of a 1.3 suzuki. Probably not a failure of the core engine.

They were popular and had a good rep. I don't know if they are still available. Pretty long in the tooth now.

It would be interesting to know if it was the engine or the redrive.

[danny_galaga]

I'm hearing this a lot in these discussions - the engine is supposed to be fine, but the redrive is a weak point. Why the hell is it so? It's just a couple of pulleys or gears in/on a housing. It's not a freakin Saturn rocket engine. Try harder, car converty people!

[facthunter]

Obviously It's NOT as SIMPLE as you infer. The reason being torsional vibration. Cars have Flywheels at the drive end and springs in the clutch and Harmonic balancers at the Other end.. ALL extra weight and cost. Nev

[danny_galaga]

5 hours ago, facthunter said:

Obviously It's NOT as SIMPLE as you infer. The reason being torsional vibration. Cars have Flywheels at the drive end and springs in the clutch and Harmonic balancers at the Other end.. ALL extra weight and cost. Nev

In which case, since only Rotax are seemingly able to build a reduction drive for aircraft engines, for safety's sake it would be best if all other punters desist. 

[facthunter]

That's JUST silly danny. Rotax have gone to a lot of trouble and expense because they KNEW they Had to.. Even Turbo Prop drive shafts  (the high speed one) will fret splines IF not Loaded either way. You avoid "floating" them. Direct drive on small engines has a lot going for it. In good engineering you don't drive a flywheel through a gear either. Have you ever Heard a loose flywheel on a motor? It gives you an Indication of the  LARGE forces involved..Nev

[danny_galaga]

2 hours ago, facthunter said:

That's JUST silly danny. Rotax have gone to a lot of trouble and expense because they KNEW they Had to.. Even Turbo Prop drive shafts  (the high speed one) will fret splines IF not Loaded either way. You avoid "floating" them. Direct drive on small engines has a lot going for it. In good engineering you don't drive a flywheel through a gear either. Have you ever Heard a loose flywheel on a motor? It gives you an Indication of the  LARGE forces involved..Nev

So what's sillier - Rotax knowing they have to try hard to make a safe gearbox, or all the car converting people (some with millions in their budgets) who don't seem to know you need to try really hard to make a safe product 😄

[facthunter]

dg, Your comment Lacked Logic. The rest of what I wrote you completely ignore. .There's plenty of reasons against Car engines & the redrive is  a KNOWN problem. Properly engineered red Gears are Usually LARGE and often Sun and Planetary which is the Best. The Prop is often a significant flywheel and it's not good to Gear a Flywheel to a crankshaft. The Pistons also perform some work as a flywheel but it's cycling where they take energy, stop and give it back. This id at it's worst in flat OR in Line fours. Best is large number of cylinder RADIALS.  Some Motors have tumbling counterweights which dynamically absorb torsional Variations. They give the reduction Gears an easier Life. ALL Gears create some frictional Losses which inevitably creates Heat. even in a small Motor it could be about 2,000 watts  and backlash or play causes Hammering. Put a stethoscope against a Rotax gearbox and Have a listen or even a failed or Loose Harmonic Balancer . These are Large forces we are dealing with. .  Nev