Electrical failures

[skippydiesel]

15 hours ago, Ian said:

Are you talking about internal engine pressure?

If more energy is released and more power appears at the crank the only way it can get there is through increased pressure or faster rotation.

Work = Force x Distance.

So if the distance remains the same the force must have increased.

The area of the piston head has remained the same so the pressure acting on it must have increased.

So more pressure.

 

A. Intake air density (cooler or hotter) will deliver more/less oxygen - more 02  better/more efficient fuel burn = more energy/power.  

 

B. Increasing intake pressure, turbo/supercharger (air pumps) will also increase O2 and  improve combustion chamber scavenging (air fuel in/exhaust out)t - both of which will result in more energy/power for a given combustion chamber (swept) volume.

 

Not so much today, with most vehicles having computer managed fuel/ignition systems but back before such developments most drivers would notice a small improvement in their cars performance during cold weather (denser air more 02 entering the combustion chambers).

 

Higher  O2 will result in higher combustion pressures & temperatures that's why turbo engines have "stronger" designs and larger cooling system capacity.

 

A is a factor of weather (ambient temperature), altitude (although there will be a progressive lowering of available 02 with HASL)  and the design of the air intake (is it being heated by the engine or drawn from outside the cowling).

 

B is when an air pump (turbo/supercharger) pressurises the air entering the inlet system - in some aircraft designs, a carefully located air inlet, may result in increased induction manifold pressure but the effect is likely small.

 

A+B is when the engine is turbo/supercharged and the pressurised air is passed through an "intercooler" to lower the temperature rise (recovering some of the temperature related losses) , that is inevitable when you pressurise air.

 

Clever engine intake/exhaust - cylinder head, valve location/size/number and piston design can go a long way to improving volumetric efficiency.

 

Due to the relatively (to direct drive) higher operating RPM of Rotax 9's the potential for intake/exhaust "tuning" to have positive benefits, is greater then the slower revving LyConJab's

 

Locating the air intake in a cooler air location, will improve (for free) the efficiency of the engine however there are many factors to consider when doing this, including the relative resistance to carburetor icing that most Rotax seem to have in Australian conditions, weight, complexity and cost..

[BrendAn]

4 hours ago, facthunter said:

I think that rotary is a long way from being viable. Sealing and heat of the ROTOR will be an issue. Just running on no load proves nothing... The wankel did proceed to a working motor  but the NSU version didn't last in the market as well as the Mazda. Nev

the mazda was not that good. my father had an rx5 with a 13b. it was interesting but gutless with any load, low torque. 4 of us were driving around templestowe one night and i was snatching gears like i was in a semi. it was ok with 1 or 2 people. i think it only got around 18 to 20 mpg. the makers of the rotary above claim they have fixed the old rotary problems. i hope they have. what do base your theory of poor sealing on. they are saying they overcame the sealing issues.

[facthunter]

I couldn't see any edge sealing and the other seals were on a large angle of change surface THAT engine is running on NO load as the exhaust noise is like a gentle Phart in church. The same part of the Rotor gets heated 3 times on one rotation so how and when does it get cooled?  Nev

[Ian]

1 hour ago, BrendAn said:

the mazda was not that good.

They can makes planes climb pretty well

Maybe you weren't driving it properly 😉

 

 

 

1 hour ago, BrendAn said:

what do base your theory of poor sealing on. they are saying they overcame the sealing issues.

Compared to a cylinder piston the area of the seals is significantly larger and the geometry is more complex. It's pretty obvious that these things are going to struggle to seal however there's also research out there which also estimates the efficiency losses due to the seals.

Modern rotaries such as the renesis are better but still nowhere near  good as standard cylinder engines. Just compare the rings of a piston engine to those required by a rotary.

[BrendAn]

1 hour ago, Ian said:

They can makes planes climb pretty well

Maybe you weren't driving it properly 😉

 

 

 

Compared to a cylinder piston the area of the seals is significantly larger and the geometry is more complex. It's pretty obvious that these things are going to struggle to seal however there's also research out there which also estimates the efficiency losses due to the seals.

Modern rotaries such as the renesis are better but still nowhere near  good as standard cylinder engines. Just compare the rings of a piston engine to those required by a rotary.

 I think you and nev need to get in contact with the liquid piston company and give them some advice. 😁. As far as the rx5 goes I don't think the old stock 13 b was in the league of that weapon in your photo.

[spacesailor]

The Wankle ' outboard motor '  had poor sealing coating. That pealed off after a couple of years.

Like a super thick Teflon. 

I know as we bought one. & yes very thirsty,  compared to standard outboard motors .

And it was fast ! ,for it's size .

spacesailor

[BrendAn]

11 minutes ago, spacesailor said:

The Wankle ' outboard motor '  had poor sealing coating. That pealed off after a couple of years.

Like a super thick Teflon. 

I know as we bought one. & yes very thirsty,  compared to standard outboard motors .

And it was fast ! ,for it's size .

spacesailor

The omc racing wankels which I don't think we're ever sold to the public performed so well that mercury had them banned from one of the major races in the USA.

[spacesailor]

I did say it WAS FAST . Compared to a standard outboard motor .

It was replace by a 90 hp outboard that practically , was far to heavy to be safe .

On a 13 foot fibre glass speed boat.

My brothers old boat was the N Z speed record holder , powered by a RR Merlin engine , double planked Kauri hull .

spacesailor

[skippydiesel]

Reference Wankel type engines,

 

The piston internal combustion engine has, I believe, it roots in steam engine technology, so we are talking what 300 years of incremental improvements .

Compare that with

The Wankel has about 66 years of intermittent development.

What might the Wankel have been with 300 years of incremental development???

 

The Wankel, like the turbine, held great promise for powering small aircraft  (terrific power: weight and smooth running) neither has panned out.

 

[turboplanner]

20 minutes ago, skippydiesel said:

Reference Wankel type engines,

 

The piston internal combustion engine has, I believe, it roots in steam engine technology, so we are talking what 300 years of incremental improvements .

Compare that with

The Wankel has about 66 years of intermittent development.

What might the Wankel have been with 300 years of incremental development???

 

The Wankel, like the turbine, held great promise for powering small aircraft  (terrific power: weight and smooth running) neither has panned out.

 

The development of man has been evolving, based on the latest Anthropological information, for about two million years, but false teeth still don't work as well as the original ones.

[BrendAn]

41 minutes ago, turboplanner said:

The development of man has been evolving, based on the latest Anthropological information, for about two million years, but false teeth still don't work as well as the original ones.

Haven't they fixed that with the latest screw in type falsys. If you break a tooth off you just need an easy out then screw in a new one.

[facthunter]

Your Jaw has still got to be in good nick. . The trouble with evolution is you can't survive through a reversal  to correct a design flaw. The species has to just press on and make the best of it . Nev

[Old Koreelah]

I’ve seen a few evolutionary dead ends.

[facthunter]

Stay away from PUBS.  Nev

[Ian]

5 hours ago, skippydiesel said:

The Wankel, like the turbine, held great promise for powering small aircraft  (terrific power: weight and smooth running) neither has panned out.

I think that the fuel burn of small turbines is what stopped most everyone in both cars and planes.

Everyone knows that wankels are thirsty, but they're practically tea teetotallers in comparison to turbines. 

[facthunter]

The wankels use a bit less than a two stroke. does. They'd suit a sports/ aerobatic  plane. They keep most of their bit's inside them. Noisy though especially when supercharged.  Nev

[Old Koreelah]

13 hours ago, facthunter said:

The wankels use a bit less than a two stroke. does. They'd suit a sports/ aerobatic  plane. They keep most of their bit's inside them. Noisy though especially when supercharged.  Nev

I saved up to buy a brand new bike in ‘75 and almost bought a Suzuki rotary.

When idling the big single rotor was noisy and vibrating like a Brit single, but as you twisted the throttle it became dead smooth. I was mostly put off by it’s large size and crazy styling.

[BrendAn]

20 hours ago, Ian said:

I think that the fuel burn of small turbines is what stopped most everyone in both cars and planes.

Everyone knows that wankels are thirsty, but they're practically tea teetotallers in comparison to turbines. 

Have you owned a rotary

[Bruce Tuncks]

 mate of mine has an ASH25 with a wankel engine and it goes great....  the engine sort of whirrs and it has plenty of power.

Of course, a glider , especially one with a modern open-class performance, does not need much reliability from an engine. My recollection of flying in the '25 was that once it was up there, it didn't want to come down. Of course this is untrue, but it sure felt that way.

[BrendAn]

18 minutes ago, Bruce Tuncks said:

 mate of mine has an ASH25 with a wankel engine and it goes great....  the engine sort of whirrs and it has plenty of power.

Of course, a glider , especially one with a modern open-class performance, does not need much reliability from an engine. My recollection of flying in the '25 was that once it was up there, it didn't want to come down. Of course this is untrue, but it sure felt that way.

Did it fold away when not being used.

[danny_galaga]

On 21/04/2023 at 3:50 PM, facthunter said:

Many aircraft alternators have to be brought onto line with a charge from the battery to excite them. If the battery is flat you cant get the alternator to charge..  There's usually a placard bear the switch(ES).  Nev

Clearly though if the airplane is flying, the battery was fine to start with. If it simply failed in flight, I agree with Spacesailor, the alternator will carry on as before. Unless the battery became a dead short 

[facthunter]

IF you don't turn the alternator OFF it's fine. When trouble shooting electrics you often do. Where this applies the switches have been placarded.  as a warning.  Nev

[Bruce Tuncks]

Yep, it folded right away into a compartment in the rear fuse. The prop was really big and this controlled how big the doors had to be.

[Geoff_H]

On 29/04/2023 at 2:25 PM, Ian said:

I think that the fuel burn of small turbines is what stopped most everyone in both cars and planes.

Everyone knows that wankels are thirsty, but they're practically tea teetotallers in comparison to turbines. 

Yet I have worked on the design of gas turbines that had efficiencies that exceed that of Otto and Diesel cycles.  They did have very very exotic and expensive turbine blades, and other expensive stystems.  I have investigated problems on Trent gas turbines and they are  very efficient, however they may work on a scaled down turbine for light aircraft, but they would be many orders of magnitude more expensive than the craft that they were powering.

[Geoff_H]

On the issue of using electronics to get more power out of aircraft engines.  The  foray of Porsche into aircraft engines proved a disaster. They had two alternates and two battery systems ( and a gearbox) as well as a system to detect if either system failed. They used diode auctioneering to get seamless changeover in the case of one system failing.  The system was heavier than the Lycoming that they replaced in the Mooney. 

Having flown  Porsche Mooney I must comment that it was the quietest least vibration light aircraft that I have ever been in.