Adeptair

[paul330]

These guys are making a V6 260-280 normally aspirated or 320 turbo-charged engine in South Africa. This video shows it ground running - very smooth. I want one for my -10

http://www.youtube.com/watch?v=Gl2QiFXl5pA

See them @

http://www.adeptairmotive.com/site/default.asp

 

[breister]

I recently heard from them that we shouldn't expect production engines for another 2-3 years. They have at least one test engine, and are partnering with Ravin Aircraft (also in South Africa, they make a kit modeled after the Piper Comanche but in fiberglass) to provide another test engine for evaluation.

Historically, no geared piston engines have survived commercially.

However, I wrote them and told them that if they have trouble with the gear box they should check out Magnomatics - makers of magnetic gears. Cannot break, reduces torque pulses, and automatically "slips" like a clutch if maximum acceptable torque is exceeded (should protect the engine from prop strikes).

More interesting to me is that Ravin is developing a twin version of the Ravin (just like Piper did with the Comanche). If they were to put two of those Adept turbocharged beasties on that airframe, that would be 640 ponies - some quick cube-root-of-horsepower calculations suggest an airplane that could cruise at well over 400mph with the oxygen mask on!

Don't worry though - I'm sure that such an airplane will cost 2-3 times as much as an RV-10 (and well out of my price range), so it will undoubtedly remain the most popular choice.

 

[Rainier Lamers]

We are very loosly involved (on the EFIS, engine monitoring side) with Adept.
Yes, it is taking time and it is taking longer than expected.
In my opinion this is mostly due to the extreme level of perfection that these guys are aiming towards and are applying to every stage of the development.
Perhaps it could be argued that this is overdone and not in their commercial interest, however, when it is done - expect an engine that is perfect...

Rainier

I recently heard from them that we shouldn't expect production engines for another 2-3 years. They have at least one test engine, and are partnering with Ravin Aircraft (also in South Africa, they make a kit modeled after the Piper Comanche but in fiberglass) to provide another test engine for evaluation.

Historically, no geared piston engines have survived commercially.

However, I wrote them and told them that if they have trouble with the gear box they should check out Magnomatics - makers of magnetic gears. Cannot break, reduces torque pulses, and automatically "slips" like a clutch if maximum acceptable torque is exceeded (should protect the engine from prop strikes).

More interesting to me is that Ravin is developing a twin version of the Ravin (just like Piper did with the Comanche). If they were to put two of those Adept turbocharged beasties on that airframe, that would be 620 ponies - some quick cube-root-of-horsepower calculations suggest an airplane that could cruise at well over 400mph with the oxygen mask on!

Don't worry though - I'm sure that such an airplane will cost 2-3 times as much as an RV-10 (and well out of my price range), so it will undoubtedly remain the most popular choice.

 

[breister]

I kinda figured they would call on you Ranier!

Well, I for one wish them success. The deck is certainly stacked against them, as every attempt ever to produce an engine which has a high power-to-weight ratio and is also geared has failed. Apparently something about harmonic feedback loops between prop, gearbox, and engine.

A friend has a scale model P-51 (80%?) with a monster 8 cylinder engine that has never flown more than 50 hours without an in-flight emergency. The Orenda engine bombed. The Merlins in the original P-51 never were reliable for more than a few hundred hours. The list goes on and on, and a lot of really smart people have tried and failed.

That's why I'm hopeful that this newfangled magnetic gear technology works out - it could solve a LOT of previously "unsolvable" problems.

 

[SvingenB]

I kinda figured they would call on you Ranier!

Well, I for one wish them success. The deck is certainly stacked against them, as every attempt ever to produce an engine which has a high power-to-weight ratio and is also geared has failed. Apparently something about harmonic feedback loops between prop, gearbox, and engine.

Not entirely correct. More than 15,000 units of the Rotax 912 is produced. It is geared and as a very high power to weight ratio, much more than any Lycoming. When knowing what you are doing, there is no problems scaling the power of the Rotax up to any requirement.

 

[dhammer]

Geared engines

Not entirely correct. More than 15,000 units of the Rotax 912 is produced. It is geared and as a very high power to weight ratio, much more than any Lycoming. When knowing what you are doing, there is no problems scaling the power of the Rotax up to any requirement.

And don't forget the GTSIO-520 that's on every C-421 built along with a few others that are a bunch more powerful per pound than the Rotax.

Many large engines are geared as well, including the largest Lycoming ever - the R-7755 at 5,000 HP for its 6,050 lbs weight.

Most sucessful of the big ones was the P&W R4360 that made up to 4,300 HP with a weight of around 3,870 lbs. Prop ratio is 0.375:1 and the power to weight ratio averaged 1.11 hp/lb. Over 18,000 were built

 

[paul330]

Well, I hope they can get it to work. Unfortunately, I don't think it will be ready to meet my timescale and the UK approval process would probably defeat me anyway

My wife is South African and we my well retire to SA in a few years. In that case, it's sell the -10 and build a Ravin with the AdeptAir engine - awesome, if not QUITE as pretty as the -10

See http://www.saravin.com/

 

[islandmonkey]

I must respectfully disagree

Historically, no geared piston engines have survived commercially.

Rotax as already mentioned. Commercially very successful.

Thielert to name another but not a commercial success.

The Vedeneyev M14P that powers the YAK 52 is also geared.

 

[breister]

Not entirely correct. More than 15,000 units of the Rotax 912 is produced. It is geared and as a very high power to weight ratio, much more than any Lycoming. When knowing what you are doing, there is no problems scaling the power of the Rotax up to any requirement.

I said it wrong - I meant both high-powered and high power-to-weight ratio.

You are incorrect - it is not as simple as scaling it up. If it were, one of the hundreds of major firms over 8 decades who have tried it would have succeeded.

I remain hopeful that someone successfully solves that problem.

On the GTSIO-520, from Wikipedia (and don't go off on whether it is a "scientific source" - I'm sure it can be independently verified and no one cares enough to falsify this...)

The GTSIO-520 was not as common and in its most common application (the Cessna 404 and Cessna 421 twin-engine aircraft) it produces 375 horsepower (280 kW). The engine has a reputation of being expensive to maintain and is intolerant of improper pilot technique.[citation needed] When operated properly, most pilots consider the engine to be reliable. Gearing reduces the RPM of the propeller making the engine quieter running than many other engines, although the gearboxes on early versions of this engine were notoriously unreliable. The gearing also adds measurably to the overhauling costs of these engines.

(bold mine)

On the Vedeneyev M14P and the GTSIO-520 - the final power-to-weight ratio of these engines are not teriffically higher than a direct-drive IO-550.

On the Adept Airmotive - even with gearing, it sits at about 1 lb per hp. Given the examples of the M14P and GTSIO-520, it shouldn't be beyond existing engineering to "get it right." What will be more exiting is when we start seeing reliable engines that break the 1:1 barrier.

 

[SvingenB]

You are incorrect - it is not as simple as scaling it up. If it were, one of the hundreds of major firms over 8 decades who have tried it would have succeeded.

I think you misunderstood me here. I didn't mean to simply multiply the dimensions with factor x, I meant scaling the power (including every engineering task required to make it work).

This has been discussed to death already, but the main factor for slowdown in engine development is turboprop. The more power, the higher the importance of power to weight, TBO, reliability, ease of maintenance, vibrations and size compared with price. Above 4-500 HP, a turboprop is a better choice commercially. Turboprops are also geared engines. There is nothing inherently unreliable with a gear, it is more a matter of a 500 HP reciprocating engine becoming extremely complex and heavy compared with a turbine.

 

[breister]

I think you misunderstood me here. I didn't mean to simply multiply the dimensions with factor x, I meant scaling the power (including every engineering task required to make it work).

I hear what you are trying to say - and please note that I am not an engineer so don't understand fully the reasons why this is such a challenge. I'm not "against it," just pointing out that if it were easy someone would have done it and cashed in.

I have had many discussions with many friends about this issue - some mechanics & engineers. I don't pretend to understand all of the issues, only the conclusions - that pretty much every time someone tries to build a really big (e.g. over 300hp) reciprocating engine that is geared and stuff it into an aircraft, they typically run into "unforseen problems." The M-14 is something of an annomoly because the radial engine design (as I understand it) has a weight advantage that gives it a higher hp/weight ratio than an in-line or opposed, and also apparently does not generate harmonics that are quite as destructive. However, I believe that the M-14 TBO is much lower than a Lycoming, and also note that a Rotax TBO is relatively low (although less expensive, too).

This has been discussed to death already, but the main factor for slowdown in engine development is turboprop. The more power, the higher the importance of power to weight, TBO, reliability, ease of maintenance, vibrations and size compared with price. Above 4-500 HP, a turboprop is a better choice commercially. Turboprops are also geared engines. There is nothing inherently unreliable with a gear, it is more a matter of a 500 HP reciprocating engine becoming extremely complex and heavy compared with a turbine.

Gearing a turboprop is an entirely different proposition - there are no power pulses at all, just smooth torque and thus ALMOST no harmonics save the expected ones based on rpm. Yes a turboprop is more viable commercially, but the initial investment is large to most individuals. Too, the fuel usage and optimum flight profile for turbines does not match well with GA requirements.

Anyway, I hope someone successfully builds something in that "space." I for one would love to swap 300+ hp for my IO-320 without materially changing weight or CG. Given the state of manufacturing, there is no real reason why such a motor has to cost 3-4 times what a Lycosaurus costs...

 

[eric_marsh]

However, I wrote them and told them that if they have trouble with the gear box they should check out Magnomatics - makers of magnetic gears. Cannot break, reduces torque pulses, and automatically "slips" like a clutch if maximum acceptable torque is exceeded (should protect the engine from prop strikes).

That is fascinating. It's rare that something really new comes along but this is the first time I've ever seen anything like it.

 

[hydroguy2]

........ I don't pretend to understand all of the issues, only the conclusions - ........ note that a Rotax TBO is relatively low
...

So you don't have to pretend and to help you understand one of the issues.
Aero-news article about Rotax TBO 2000hr

 

[breister]

So you don't have to pretend and to help you understand one of the issues.
Aero-news article about Rotax TBO 2000hr

Glad they've successfully upped the Rotax TBO. Wish they had one in the 300+ hp range...

 

[breister]

That is fascinating. It's rare that something really new comes along but this is the first time I've ever seen anything like it.

I thought so, so much so that I contacted several of the folks attempting geared engine designs to let them know about it. I believe it may mark a true paradigm shift, and may lead to much higher hp/weight ratios in aviation engines.

But I've been fooled before!

 

[SvingenB]

I have had many discussions with many friends about this issue - some mechanics & engineers. I don't pretend to understand all of the issues, only the conclusions - that pretty much every time someone tries to build a really big (e.g. over 300hp) reciprocating engine that is geared and stuff it into an aircraft, they typically run into "unforseen problems." The M-14 is something of an annomoly because the radial engine design (as I understand it) has a weight advantage that gives it a higher hp/weight ratio than an in-line or opposed, and also apparently does not generate harmonics that are quite as destructive. However, I believe that the M-14 TBO is much lower than a Lycoming, and also note that a Rotax TBO is relatively low (although less expensive, too).

Gearing a turboprop is an entirely different proposition - there are no power pulses at all, just smooth torque and thus ALMOST no harmonics save the expected ones based on rpm. Yes a turboprop is more viable commercially, but the initial investment is large to most individuals. Too, the fuel usage and optimum flight profile for turbines does not match well with GA requirements.

First of all, power pulses from a V6 and even more so a V8, are nowhere near as destructive as from a 4 cylinder of any configuration. Rotax (with 2000 h TBO on their 912 ) also have made a larger V6. But they decided not to put it into production because it would not be viable commercially.

Power pulses is not a problem, it's a myth. For instance on the Rotax, it is only at very low RPM and at a very specific airspeed when the mean torque is zero that this could be problematic. This specific problem is handled by the clutch on the Rotax. If I remember correctly, the engine manual states this, running the engine with zero mean torque will make excess weir on the clutch. On a V6 or V8 the same problem would in theory exist, but I doubt that it would be a real issue due to the smoothness of these engines even at low RPM compared with a 4 cylinder engine. Even so, a simple clutch would fix any eventual problem of this nature.

There are just as much harmonics in a turboprop as in any other geared engine. Harmonics is not directly connected to power pulses. As with Rotax engines, all turboprops are designed so that the harmonics does not occur within the actual RPM ranges.

 

[breister]

First of all, power pulses from a V6 and even more so a V8, are nowhere near as destructive as from a 4 cylinder of any configuration. Rotax (with 2000 h TBO on their 912 ) also have made a larger V6. But they decided not to put it into production because it would not be viable commercially.

Do you know that for a fact as an insider, or are you assuming? I'm curious, because I followed that engine development for a while. In any case, the engine was <= 300hp and the hp/wt ratio was not nearly as good as the 914. From an archived article on the internet:

"The fully configured V300T complete with a 130-amp alternator, 70-amp alternator, and air conditioning compressor weighs 570 pounds, slightly less than a comparable conventional engine."

Didn't sound revolutionary to me, and if prices were like the 914 then a 300hp engine would have been well over $100k. Here is a longer article.

Power pulses is not a problem, it's a myth. For instance on the Rotax, it is only at very low RPM and at a very specific airspeed when the mean torque is zero that this could be problematic. This specific problem is handled by the clutch on the Rotax. If I remember correctly, the engine manual states this, running the engine with zero mean torque will make excess weir on the clutch. On a V6 or V8 the same problem would in theory exist, but I doubt that it would be a real issue due to the smoothness of these engines even at low RPM compared with a 4 cylinder engine. Even so, a simple clutch would fix any eventual problem of this nature.

There are just as much harmonics in a turboprop as in any other geared engine. Harmonics is not directly connected to power pulses. As with Rotax engines, all turboprops are designed so that the harmonics does not occur within the actual RPM ranges.

I believe you - sounds like you've got an engineering background.

Still, I'll stick with my original assessment: If it were easy to make a reliable geared infernal combustion engine over 300hp with better power-to-weight ratios than direct drive, someone would have done it.

I really, really hope they do!

 

[SvingenB]

The press release from Rotax:
http://www.rotax.com/en/Media.Center/Press.Releases/1/20061114.htm

Although they don't say it out load, it is obvious that the engine would not contribute in a positive manner with the cash flow for the company.

"Didn't sound revolutionary to me, and if prices were like the 914 then a 300hp engine would have been well over $100k."
That is the main point. There is nothing revolutionary about any geared engine of any HP rating. They just become increasingly complex and costly for every added HP. The FADEC alone is probably just as costly to develop and certify as the engine. When the market is limited, and the only added value for the customers are simply "different technology" with no real benefits for 2-3 times the price of a Lycoming, then why bother?

I also think that folks greatly underestimate what a truly brilliant design the larger Lycomings are, O320 and up. They are much like the bicycle, a perfect combination of function and simplicity.

 

[eric_marsh]

I thought so, so much so that I contacted several of the folks attempting geared engine designs to let them know about it. I believe it may mark a true paradigm shift, and may lead to much higher hp/weight ratios in aviation engines.

There are two possible drawbacks that come to mind. The first one is it would seem like it would take some really massive magnets to hold a couple hundred horsepower and that could get heavy. The other one is that exotic magnets would probably be pretty expensive. But this is really just speculation on my part.

Regarding the overall conversation, while modern engines create a lot of power for each pound of weight they do so spinning faster. This means increased dynamic forces and just plain greater wear, both of which will decrease engine life when compared to a slower turning engine. I don't think you can have your cake and eat it too on this one. It's a whole lot easer to make a 3000 rpm engine go a thousand hours than a 6000 rpm engine.

 

[breister]

There are two possible drawbacks that come to mind. The first one is it would seem like it would take some really massive magnets to hold a couple hundred horsepower and that could get heavy. The other one is that exotic magnets would probably be pretty expensive. But this is really just speculation on my part.

Yeah, I don't know anything about the cost - but then again, a gearbox with no physical contact would never need overhaul so it might be worth a bit of extra expense. Too, they say the weight is comparable, or even less, for gearboxes (mechanical vs. magnetic) handling equal horsepower. Here is a video showing a high-power demonstration adding resistance until the maximum shear force is reached, then released until it re-engages.

Regarding the overall conversation, while modern engines create a lot of power for each pound of weight they do so spinning faster. This means increased dynamic forces and just plain greater wear, both of which will decrease engine life when compared to a slower turning engine. I don't think you can have your cake and eat it too on this one. It's a whole lot easer to make a 3000 rpm engine go a thousand hours than a 6000 rpm engine.

Hehe - I got corrected a few posts back about Rotax, which spins rather fast but is now up to a 2,000 hr TBO. Too, Rotax overhauls are supposed to be far less expensive than Lycoming O-200/235s. A smaller displacement water-cooled engine with tighter tolerances might or might not last as long, I don't know - but until they solve the gearbox challenge for good there probably will not be significant effort spent to find out.

If you can toss in a Chevy engine for $4,000 brand new, and get 1500 hours out of it, who cares what overhaul cost is? Buy a new one and sell the old one to a gear-head for a hot rod.

 

[rv72004]

We are very loosly involved (on the EFIS, engine monitoring side) with Adept.
Yes, it is taking time and it is taking longer than expected.
In my opinion this is mostly due to the extreme level of perfection that these guys are aiming towards and are applying to every stage of the development.
Perhaps it could be argued that this is overdone and not in their commercial interest, however, when it is done - expect an engine that is perfect...

Rainier

Rainier,
maybe you could convince the guys to post here and keep us in the loop.
Just like the info you post about mgl, its very informative.