Interesting new engine

[Guest Flyer40]

George, I'm concerned that you felt the need to respond to things I didn't say, so without meaning to sound patronising I'll clarify them.

 

But first, can you explain why you think a certification delay should give me pause for thought? The only thing I would take away from that is to be even more reassured about the rigor of the certification process and therefore the safety and reliability of the final product. How many Boeings Airbuses, Lockheeds, Pipers and Cessnas have experienced certification delays, and what did it result in other than a better product? My own experience has shown that certification delays are often caused by the certification process itself having to catch up with emerging technologies. Unless you're in a hurry, certification delays usually do good things.

 

I did not compare the UL260 to the TCM. As I did say in my first sentence, I was comparing the relative merits of the technology. In simplified terms, electronic engine control verses mechanical. No deception OK.

 

And finally, I did not "dismiss the chance of an electrical system failure as insignificant". What I did do is dismiss the consequences of an electrical system failure as trivial, thanks to system redundancy. The likelihood (chance) and consequences are totally different things, but they are both necessary to determine the level of risk.

 

Mal

 

 

[Guest browng]

George, I'm concerned that you felt the need to respond to things I didn't say, so without meaning to sound patronising I'll clarify them.

No need to be concerned, I do not feel in the least patronised, particularly as I was not responding to things you did not say at all, but simply making comments of my own on the general subject of FADEC technology as applied to aero engines. I prefaced my comments with "While not disagreeing with your stated aim, there are a couple of points I feel the need to make here". In other words, I agree that the aim is commendable, but do not share your view that FADEC has yet proven itself a major advance for aero engines because, "There are FADEC Continentals in operation proving this every day of the week". The TBO of the TCM FADEC engines is 2,000Hrs, exactly the same as their conventional engines, and as yet the operational data is a tiny fraction of that available for conventional engines. FADEC may well prove to be all it is hoped, but it is still very early to state that they are superior, or even equal in reliability to engines with a 75 year history of safety in operation, when they themselves have only been available for around 3 years.

 

But first, can you explain why you think a certification delay should give me pause for thought?

Because it was extremely difficult for TCM to deliver an engine that the FAA considered reliable, at least one aircraft manufacturer, The Express Aircraft Company, went broke due to difficulties with the TCM FADEC engines, mainly software problems as I recall. The pause for thought relates not to you specifically, but to anybody considering an engine from a small manufacturer using a technology that the hugely resourced TCM took years to get right for an aviation application.

 

I did not compare the UL260 to the TCM. As I did say in my first sentence, I was comparing the relative merits of the technology. In simplified terms, electronic engine control verses mechanical. No deception OK.

I said that a comparison is deceptive, not that anyone was trying to deceive, and I stand by that. The great complexity and redundancy of the TCM system is in a different realm to the UL260i, but unless one is aware of that, the use of the term FADEC for both could indicate a comparison that is not in any way justified. As to the merits or not of the technology, it's early days, but personally I am yet to be convinced that an aero engine operating either at full throttle or at a fixed rpm for the vast majority of its life, will glean much benefit from this technology beyond the politically driven environmental benefits and marketing 'product differentiation', unlike a car engine that must be efficient throughout its rev range, where the benefits are self evident and the consequences of failure minimal. And again speaking personally, I prefer an engine that can be serviced and diagnosed with a feeler gauge, not a diagnostic system costing thousand of dollars, well beyond the grasp of the typical L2, and even the majority of self employed LAME's.

 

And finally, I did not "dismiss the chance of an electrical system failure as insignificant".

Again, I didn't say you did, to be precise I said " It is tempting to dismiss the chance of electronic failure as insignificant"

 

 

[Deskpilot]

My God, all I did was ask you to view some new technology. Lets get back to the Revetec engine. Less moving parts = less lost energy = money in your pocket. Also, the most stressed components of a 'normal' engine, are done away with, ie crank shaft, con'rods and associated bearings. The two, contra rotating cams must also make the engine almost free of vibration therefore benefiting the airframe.

 

Whether the engine is just a basic carburetted type or a super duper injected monster with FADEC and all other bells and whistles is not important. Here we have another Australian invention that too many people will turn their backs on because they're too afraid of change. Open your minds, people, this is not an auto-conversion, it's a step into the future. Empower it rather than dismiss it. Encourage this team of engineers and their design. All I hope is that Chinese production methods don't wreck it. Who knows, in a year or so, there could be a worthy competitor to Jabiru.

 

 

[Guest browng]

My God, all I did was ask you to view some new technology. Lets get back to the Revetec engine.

Fair point that, we got a bit sidetracked there. I have one question about the Revetec; without a crankshaft (and I presume therefore a flywheel), will this engine be able to produce enough torque to swing a decent prop without a re-drive? I sure hope so, because it's form factor would be a godsend to builders of replicas that were originally powered by rotaries or radials.:) This may be a partial answer to my own question; "Revetec’s design holds a maximum torque lever over a greater number of degrees of rotation, which transfers the torque to the output shaft more efficiently the entire rev range." but that of course depends on what base torque it is developing to begin with.

 

 

[Deskpilot]

George, have you view the videos of this engine? The cam assemblies appear to be pretty big so no flywheel is required.

 

 

[Guest browng]

George, have you view the videos of this engine? The cam assemblies appear to be pretty big so no flywheel is required.

Unfortunately I can't view videos at work, bloody IT dpt, but I would be very interested in an rpm/torque comparison with a 4cyl Jabiru. the Revetec X4 claims' "125Nm@2,000rpm, peaked at 140Nm@3,700rpm and maintained 115Nm@4,700rpm"

 

 

 

Does anybody have the Jabiru torque numbers handy? Their website doesn't seem to quote them.

 

 

[slartibartfast]

2200 Power Curve

 

[ATTACH]4260.vB[/ATTACH]

 

Here's the power curve from the manual.

 

 

 

[facthunter]

Balance and torque

 

I cannot see why you would consider this camplate principle engine to have a balance advantage. In fact ,as opposing pistons move in the same direction, there is no natural balance as in the Flat (boxer) engines, where they move opposite and cancel out the inertia of the reciprocating parts. ( I'm neglecting the rocking couple remaining due to the fact that the cylinder centres are not in line).

 

This engine should develop high torque because the piston motion is controlled by the cam shape, which the designer can alter. Also it appears as if ,with one rotation of the mainshaft, the piston will stroke 3 times, giving effectively a 3 to 1 reduction which would be a distinct advantage. None of the power section of the engine is shown, so I presume it is conventional. I can see a lot of inertia loads being generated inside this engine, and I would have to be convinced that the "crank" replacement (bottom end) could be made strong enough. I have no doubt that it can be made to run, but that's not the whole story and I think it will have a vibration problem. Nev..

 

 

[Guest browng]

[ATTACH]3741[/ATTACH]Here's the power curve from the manual.

On that data the Revetec seems very low on torque compared to the Jabiru, it produces less continuous torque at higher revs, i.e. 115Nm@4,700rpm as compared to almost 200Nm at 2500rpm for the Jabiru. The Jabiru drops off at higher revs, but not by a significant amount, and even at peak revs the X4 only produces 140Nm. On those figures it would seem to be more of a competitor to the 2-strokes than the 4-strokes.

 

 

[Yenn]

If my memory serves me correctly the Mooney, Porsche plane was pretty good but as maintenance came up on the motor, Porsche said they would replace it with one of the conventional engines "can't remember which" and take the Porsche out of service.

 

I don't think there was any great problem but Porsche had had enough.

 

 

[Guest browng]

If my memory serves me correctly the Mooney, Porsche plane was pretty good but as maintenance came up on the motor, Porsche said they would replace it with one of the conventional engines "can't remember which" and take the Porsche out of service.I don't think there was any great problem but Porsche had had enough.

The problem was weight, the Porche engine was very heavy, but the engine weight was not the only problem, the PFM required complicated ancillaries as well. The Mooney Porsche was about two hundred pounds heavier than the Mooney 201. The installation was also bulky with a fairing drag penalty, all in all it was a bit of a disaster. Ironically, to get the performance that they had sold the buyers, Mooney replaced the PFM with the turbocharged Lycoming TIO-540, which was only slightly lighter, but produced more power.

 

 

[jetboy]

In considering the revetec I favour a couple of other new designs: (because I'm still waiting to see a Dynacam or Zoche that goes anywhere on a plane)

 

http://www.dair.co.uk/

 

and

 

http://www.masschimotors.com/

 

of course we still have to wait till they exist in production and are competitive for both cost and reliability.

 

Ralph

 

 

[Deskpilot]

Suggested reading:

 

http://www.revetec.com/advantages.htm

 

 

 

View also the 3D cad drawings. This is a four cylinder, X config engine with the same balance (if not better) than an ordinary boxer flat four. As I said before, contra rotating trilobe cam drivers, with or without a fly wheel, I believe will produce a much smoother motor.

 

 

 

[Guest ozzie]

Ah, the PFM

 

Interesting engine. had the chance to work on one years ago. the actual engine is sound. it was the nightmare electrical system and electronics that would be the source of most problems. from memory ,2 batteries 2 alternators 4 cdi units, 1992 electronics driving ign fuel and prop. once you move away from magnetos redundency becomes complicated.

 

this mooney came in for an AD on the gearbox casing and a 100hrly.

 

ozzie

 

 

 

 

 

[facthunter]

Balance?

 

Doug, we will have to disagree on that then. I'm happy to stick with what I have already said.. Nev..

 

 

[Guest ozzie]

Hi Ralph, you mentioned the dynacam engine this is one that i have been watching for about 20 years. it has flown on i think an aztec quite a lot of hours, it has been shelved brought back shelved again and brought back. great concept of an engine so smooth it can be sollid mounted. lots of power ect. unfortunatly the wear on the cam that drives the double headed pistons is so high that it will only get a few hundred hrs before it needs replacing. so until they come up with some super tuff metal to handle the wear it will remain just a concept engine

 

Ozzie

 

 

[Guest disperse]

My 2 cents ..... although a while off . I've been looking at the http://www.rotamax.net/aviation.html But I think a big restriction on "NEW" design is the natural human behaviour, to feel comfortable with what you know

 

 

[jguscott]

Very interesting, i will be watching these guys with interest

 

 

[Deskpilot]

Welcome Revetec, great to hear from you. I look forward to your news and report with interest.This thread has spent too much time looking at the past failures instead of viewing whatever might be a success in aviations future.

 

 

[Deskpilot]

Anyone wanting to catch up on this subject, read the following report. It gives all the design parameters of this exciting new engine.

 

http://www.revetec.com/news3.htm

 

I haven't checked but it might not contain the latest figures reported by revetec

 

 

[Admin]

Guys, I would be very careful when considering this revetec engine. Make sure the support is there and that you are sure that if you ever do have a problem it will be met with good support as this goes with any engine. Being new it is unproven, support is unknown but only time will tell - just my opinion

 

 

[Guest airsick]

Quick question re this engine. A conventional engine (4 stroke) has an intake, compression, power and exhaust stroke. So the piston is at top dead centre and is pulled down by the crankshaft to 'suck' in fuel and air. It is then pushed up to compress, fires and pushes itself back down and then gets pushed back up to exhaust the spent gases before beginning the entire cycle again. Aside from when it is self propelled downwards on the power stroke it is relying on the work of other pistons and the crankshaft to move it around.

 

With the Revetec engine I can see how the cam will push the cylinder up for the compression and exhaust strokes. I also understand that it will move downwards on its own during the power stroke. My question is this - what pulls it down on the intake stroke?

 

 

[Admin]

Airsick

 

Revetec is currently on a ban for abusing the privileges of the forums and very distasteful PMs so he will not be able to respond at the moment.

 

 

[Guest airsick]

So it is a bad attitude weighing down the piston then?

 

 

 

[Deskpilot]

Ian, I had a pm from revetec and he states that the ban was due to the topic being viewed, by you, as commercial and for financial gain. If this is the case, bearing in mind the the engine is only in the R & D stage at the moment (just like the Millennium Master) and none are offered for sale (just like the MM), perhaps you should consider removing all mention of the MM for the same reason. I would hate for a case of 'double standards' to be apparent within these forums. It would also indicate, that we can't mention any performance or design details of any engine manufacturer from now on?

 

If there are distasteful pm's involved, I'm sure an apology would be forthcoming if asked for.