On the RAR news group there was some conjecture that Robinson were soon too announce a Diesel powered ( French of German ) engine R44 . The french one claims 3,000 hr TBO and 30 % les fuel cost. Do you think it would catch on ?. I've been told engine is around 80K usd.

I have no idea whether Robinson are developing a diesel Robbo, but here in Europe where Avgas is both very expensive and soon likely to be scarce it seems like a great idea. Avgas is around 90 p per litre with Jet A1 around 30-35 p. Aside from reduced fuel costs, you don't get carb icing, and I would much rather carry a tank full of Jet A1 than Avgas around with me.

All of these things matter much less across the pond, let alone in California. I hope the rumour is correct or stimulates the factory or some other outfit to look at it.

Generally, diesel engines weigh considerably more for the same power, because of the heavier structure in the engine to withstand the very high compression required to ignite the fuel. Diesels burn less fuel in the job, though so they offset some of the engine weight. Diesel aircraft are rare because of the weight issue.

There are two types of Diesel engines. The one mentioned by Nick fires by the heat of compression and in many cases has a blower of some type acting to pre-compress the charge although some compression Diesels do not employ a blower. As Nick indicated this type of engine is quite heavy for its’ physical size. This type of engine is normally of the two-stroke type and runs at a lower RPM than the engine type described below

However there is another type of Diesel engine (referred to as Hesselman Cycle) and this type of engine uses glow plugs to ignite the fuel and as such does not require the robust structure employed on a compression Diesel engine. As a result they are much lighter in weight. There are several German companies developing radial Diesel engines for use on aircraft.

As stated by widgeon, a similar topic was discussed in rec.aviation.rotocraft. The original post had nothing to do with diesel engines in Robbies, however the discussion turned in that direction. There was speculation about an R55 / R66 – turbine, turbo, diesel etc … all speculation !

One of the things that was uncovered was that there are a few companies developing diesel aviation engines. The first consensus was diesel’s will never hack it, they are too heavy ….. well if we examine the Zoche vs the Lycoming we get :

ZO 02A 530. .Height 25.5 24.5. .Width 25.5 33.3. .Length 32.9 37.2. .Weight 271 369. .HP 250 300

Zoche also claim sea level performance up to 9000 ft. Believable if you consider the major advancement in diesel technology in the past 2 years or so. Ever driven the latest BMW 530D. Before I get shot down, I know the BM doesn’t have a Zoche under the hood, however technology has advanced and performance / reliability has had a serious shot in the arm.

I’m a recreational pilot and only fly for the pleasure of it and all my flying is done above 6000ft, in fact I have only ever logged 1.5 hr at sea level. If there were two 44’s next to each other, one standard and the other diesel, it wouldn’t be a difficult choice for me to make to fly the diesel version. We always joke here, the 44 is a great 2 seater ! Considering we all trained in the 22 and still fly them all the time, maybe there should also be a diesel option for the 22 !

The weight issue is no longer such a big deal - I would hesitate to use Zoche as an example - he has spent more money on attending Oskhosh than on developing his engines! However if you look at the Thielert it has a similar firewall forward weight to an O-320. The Thielert is 135 hp and obviously the Lycoming 160. Once you are over 3000' then the Thielert is more powerful. Now given that the Thielert is a Mercedes conversion the arguments about diesels being a lot heavier seem to fall to bits.. .Dedicated designs, I suppose the Wilksh is closest at the moment should be a lot lighter - the 120hp wilksch has a target weight of 100kg, versus the 137 kg of the Thielert.. .Even the Renault engines are said not to be much heavier - and the fuel burn is so much lower that the extra weight is not a handicap.. .Given European fuel costs there is a real need for these fuels - lets hope the rumour is true!

I know that it is an aeroplane and not a helicopter but I've flown a PA28 fitted with a 1.7 litre diesel in Germany and there is a DA40 flying in Austria with the same engine. Diamond hope to bring the diesel version to market sometime later this year. In addition they hope to fly a diesel twin (aeroplane) at ILA Berlin later in the year. SMA are also producing aero diesel engines.. .<a href="http://www.thielert.com/en/index.html" target="_blank">Thielert</a>

Whilst Diesels now seem to be the fashionable thing for GA FW's to think about, I do feel that a thumper in the back of any R22 or R44 would be very counter productive, in my humble opinion the only way forward for the light helicopters is to go turbine, Now the R44 with a turbine and a three or four blade head, and individual cyclic's would be somthing that would be worthy of sitting in everyone's front garden, it might even allow the rear end of the R44 to be finished off properly, rather than look like it has has some collision with a low brick wall! After all we are told that the Jetranger is being stopped, so uncle Frank could step in and take the lead in small privatly owned Helis for the future. :)

If someone could come up with a small turbine that had reasonable purchase cost and more importantly overhaul costs then it would be possible.R44 is currently 310K USd extra purchase cost with current certified turbines would be closer to 500 K usd ( Engine exchange cost is 21K allison 250 is closer to $200 k ). Operating cost is 124 USd/hr , turbine overhaul reserve would add minimum of $50 an hr. The Enstrom turbine has not been exactly flying of the shelves .

There is a discussion about diesels on the TECH forum.

I think they would be a great idea as in remote areas it is a lot easier to find jet-a1 than avgas.

Another benefit if there are many aircraft working at a remote site i.e. forest fire fighting . .the contracting agency would only need to stock . .1 type of fuel .

I wonder if anyone has thought about fuel cell applications for light aircraft - seems to be the wave of the future for cars - if you listen to the media.

I think the diesel heli idea has a lot going for it.

As well as fuel commonality mentioned earlier a decent range might be possible.

Being more efficient there's less waste heat to lose, and presumably less useless time needed for warm up and cool down.

Possibly more tolerant of abuse, and surely a longer TBO just like road engines.

For me the greatest bonus is losing the magnetos and carby ice.

Brilliant, hope they do it :)

1. Avgas is the only leaded fuel around here. Since the airplane fuel usage vs. automotive usage is just a drop vs. ocean. Not only ecology but also oil rafineries will drive out avgas - (not all engines can accept Mogas).. .2. Current piston engine designs are unbeliveably obsolete,(thirsty, ecollogicaly unacceptable, heavy) Nor Lyc nor TCM considers any radically new gasoline powered design - they even work on their own diesels (maybe to little, too late). .3. Small turbine which is affordable, is not achievable (yet). .Considering these facts, SMA (Renault), Thillert...diesels are the way we will go in piston engine powered aircrafts.. .First Tillert conversion is hopefully coming to an aeroclub nearby - I`m barely waiting to check it out!. . Mihael

I remember seeing on the discovery channel a bus that was powered by a small turbine, I was not sure of the model or manufacturer but it was used solely to generate electricity for the bus. It was also very fuel efficient. Perhaps the technology does exist?

Diesel powered rotary
 

Now that the fixed wing fraternity have a Jet A powered craft when will the rotary wing manufactures follow suit.

Why should helicopters designed in recent years be powered by engines of the 1930's?

Will Robinson, with it's huge output of rotorcraft lead the field?

Anybody know anything on this?

HT,

Its an interesting thought - there has been at least one extensive thread in the past with, as I recall, all sorts of interesting perspectives. Have a look when the search function is operational.

It would not half bring down the cost of operating an R44, for example.

Just two weekes ago I sent a e-mail to Schweizer asking if they were considering installing a diesel in the 300C. Maybe something like the SMA 230 hp engine.

I received response immediately and they said they were indeed considering diesels but at the time they were not an option due to cost but they were following all advances in the diesel tecnology.
They also said that the SMA diesel, although in the same horsepower category as the HIO360 D1A Lycoming at 225 hp was to heavy to be feasible.

Diesel Engines
 

This web site may be of interest; DeltaHawk Diesel Engines

Ditto for the second half of this page; The Front Royal Unicom

Dave J.

I think this one should also be here "Randcam Rotary Diesel" at least it has power to weight ratio around 0,34kg/hp when most piston engine are between 2-3kg/hp. lycoming maybe 1,5kg/hp
so from fact that you could have 230hp engine that where 80kg
sounds to good to be true
http://www.regtech.com/

Ah, the advances in technology. How about maybe a Coal/Wood Fired Steam Engine. That way the Robbie could justify a flight engineer also to shovel fuel.......
Better yet...Nuclear Power.....The new age of Crash and Glow.......

Hi

diesel in aviation, is still making is first baby steps (in the fixed wing world) so to "jump" to the rotory world, will take a little more time (i think ... :O )

plus, if you think, for example, in the "Uncle Robby" models, where we like it or not they are the best/more selled models, until there is a "new kid on the block" they don't need to improve/go step futher using diesel engine... (don't know if make my point... :hmm: )

only to know, another brand that advertises aero diesel engines for years, but still don't know how it goes this days is

ZOCHE aero-diesel

happynewyear
regards

Diesel engines will never be the best choice of engine for helicopters, unless the objective is to have a helicopter whose sole purpose is long range flight.

If any of the manufacturers were to design a new helicopter today they would not choose a diesel engine over a Ly-Con, Bombardier or turbine. For the simple reason that the weight of a diesel engine in a helicopter would marginalise the performance of the machine to such an extent that it would not be worth bothering! Yes, Avgas is expensive and yes, helicopters burn rather a lot of it, but even in 'rip-off-Britain' the fuel cost is typically only ~25% of the true operating cost of the machine. Further, if we all switch to Jet fuel then how long do you think it will be before the government bump up the tax on jet fuel for GA customers!

Helicopters designed and built today will be in service for at least 2-3 decades and so critical design decisions like the one relating to the powerplant must be made to create the best helicopter possible and not pander to current tax laws for an apparent 'easy-saving' on DOC. Imagine what would happen if the government increased the tax on Jet fuel for GA users and a manufacturer had just built a new machine with an over-worked aero-diesel engine (to get a sensible power-to-weight). The machine would be more expensive than a Gasoline/Avgas equivalent, would have less payload, perform worse, require more maintenance and would likely be less reliable (for a number of reasons)...then the tax goes up and all of a sudden its no cheaper to operate either! Just food for thought…

Also if a manufacturer was going to design a new engine for a GA helicopter it would not be a diesel engine - as they will always be much heavier than any of the serious alternatives. It is possible to design modern gasoline engines that are very efficient (in comparison to existing aero 2-stoke diesels and in particular Ly-Con engines) and there are many other propulsion technologies that provide interesting opportunities.

Diesel cycle engines are not the way forward for helicopters, as we will all see in due time.

Hope this helps

Christmas CRAN
:ok:

Cran

Please explain how some Swedish guys have a 300C up and flying with a diesel. Pilot mag about 6 months ago. A modern diesel engine is close to 75% thermaly efficient, is pretty light and produces a serious amount of torque.
Compared to a 1930's engine - eg HIO360D1A in a 300C which is very expensive to run and maintain.

Lets face it we have put up with rubbish engines for way to long. I have recently been training the owner of one of the big GB rally teams. You should see his face when one explains the finer points of a Lycoming and Magnetos !

A question for all you piston rotorheads - if you spent £ 15000 on a car would you expect it to use 1 litre of engine oil every 4 hours / 300 miles ? i would be taking it back to the manufacturer, The Dept of Trade and Industry would be sueing over " not fit for purpose " But us aviators will spend £15000 on overhauling the lump of Cra_. !!!!!!!!!!!!!!!

Hughes500,

Cool your jets. If you have an engine that is 75% thermodynamically efficient, run, don't walk, to the patent office, you are an instant millonaire!

The hype in the above posts is like those internet legends about an engine that runs on water, but is suppressed by the "oil companies" or some such truck.

The figures given by rotorrookie are truly from a rotor rookie, the typical helicopter gas engine weighs about 0.66 Kg per HP, not the inflated numbers he found somewhere. While there might be some advantage to diesels in aircraft, I think the data must speak for itself, and it should be good data, not that drawn from sites that are selling.

I'd suggest that you have a bit of trust in the guys who build what you fly. Do you feel like the people who design and build the machines know what you do? Do you think the design engineers at the manufacturers wait for the latest "Pilot" magazine to help them drum up new ideas?

The engines we use are proven and work well. The margins in the helo industry don't allow much error in picking the engine. I am also intrigued by the web site that shows a diesel that is 10% lighter than a gas engine (nice trick, when the 17:1 compression ration dictates much higher stresses and more engine structure to withstand the ass-kicking thoise pistone give the engine). I am not saying that I disbelieve the diesel sites, but I surely would like to see their Type Certificate Data Sheets, issued by a strong governmental test org, before I took those figures to the bank (or trusted my family to the reliability of the engine they are selling.)

Frankly, the Deltahawk site impresses me, the figures look about right, and the engine is not overplayed. It will be quite something if they make a good FAA certificate, but they haven't even started down that path. Note the worry about endurance at high power. This is where you cut the nut in engine design/test. I wish them best of luck, but FAA test is when the fun begins, I think!

Nick, here's the FAA Type Certificate for the SR305-230 diesel engine.

FAA TC - Societe de Motorisation Aeronautiques (SMA) SR305-230 diesel engine

SMA SR305-230 engine, general info

Diesels
 

Cran

I am surprised with your firmness on the diesel 'unfitness'.
Does any one have specifique power figures and tendencies ? (Nick gives .66 Kg/Hp for avgas, of 1.5 lbs/HP, I would put diesels at 2.0 lbs/HP)
It seams to me that at least the diesels are catching up. At least in cars they really do.
In aero (wing) Thielert and their new V8 (certified now in the HP-plane) looks impressive.
It still is perhaps 100 lbs too heavy, but I think at full range it can, save almost 100 lbs on fuel, so in my opinion it is getting close. Tax can be a non- issue but lead is not just a tax issue it makes avgass expensive (somebody told me it only takes a few days to make the world production and it is quite expensive to clean the system after a production batch)

delta3

Hi

again:

diesel engines are STILL making is first steps in "flight environment", because of many reasons... certification, reliability, etc...

but they will come to stay (i believe... :O ;) ), right now, with present models, it's not worthy to try to use them in rotor world because the bad thing's that they (still) have don't outcome the plus things they have, when compared it "normal" av-gas pistions
(weight/power, reliabilty, new tech/high cost, etc.. )

(in the fixed wing world, they already are making some ground ....)

maybe i'm nobody, and for sure that i don't know mutch... but if you believe in history, and you are in europe (sorry rest of the world), you can see how in the automobile industry, every one is going crazy with diesel, when, at what 10 15 years ago, diesel car engines were slow noisy undepowered smokysh and so one...
now every one whats a diesel.... :)

there was a great improvement in technology, high investment, etc... and a great pie of all auto engines became diesel..

if you think/extrapolate to de flight cene, and remember that the piston engines technology, has allready a "few" years old, plus a huge investment in this "new" diesel tech... will see that in few years there will better diesel engines and will overcome in some aplications the "old" av-gas pistion...

regards

happynewyear

edit: to put a few more lines

the fuel consuption is another issue (you can see with auto industry if you like), vif you can have the same power, it more or less the same engine weight, but with a lower consuption, it's not dificult to guess to where "everybody" falls ;)

even more truth, in rotor world (i will not give numbers, because i don't have any, but if anyone have... lets see..)

pick an piston engine heli, see how much fuel it carry and how much uses in a given time (so far , all possible), pick an "example" engine (say it's the same size / power and weight... maybe not truth right now, but will be... or will weight the same, and "drink" less, or will have more power..), and make the math to our heli, with this new engine... ans see how much payload you can carry or how far you can go more

regards

delta3, the above mentioned SR305-230 comes in at .83kg/hp or 1.84lbs/hp (based on installed weight of 423lbs(192kg), and 230 hp).

Hello everyone,

the quest for diesel-power is not so much for "true diesel power" as in "compression ignited fuelmix", but for an engine that is substantially cheaper than a turbine and can "eat" Jet-A or Diesel.

Gasoline costs are getting out of hand in a lot of parts of the world.
In Europe, a diesel conversion that costs twice as much as a new gasoline engine is amortized in less than 300 hrs flying!!
Jet-A is cheap and available everywhere.
So it is not necessary to have a REAL Diesel engine, but rather one that can burn Jet-A/Diesel in some way...

I guess Mistral-engines of Switzerland will be the first to certify a Jet-A powered engine at about the same cost as the Lycosaurus engines.
As far as I understand the engines are rotary-design (like the Mazda rotary car engines). Naturally aspirated or turbocharged 2 and 3 rotor engines from 190hp to 360hp, gasoline or Diesel/Jet-A burning.

The Jet-A versions will have a computer controlled fuel injection AND IGNITION! So it does not need the diesels inherent need for ultrastrong structure.
A relative low overhaul-cost after a 3000 hr TBO should help to float the product too. Certification for the gas-powered 2-rotor engines is expected for 2005.

Mistral also flys a Turbo Arrow III with Embry Riddle in FL, no problems so far (this is a gas-powered one....)

The Jet-A burner is running on the dyno already.....

Check it out!! http://www.mistral-engines.com/


3top:cool:

PS: The Mistral engines match or beat the power-equivalent Lyc/Cont engines with installed weight incl. systems - cooling, etc.

The way I remember it from my fw-flying, wasn't NASA involved with a couple of companies to develop new engines, including cheap turbines? Now that is definately much more interesting.
A small sturdy FADEC-turbine with a simple design, yummy!

/2Beers

Well Nick I got these figures from that website without taking a second look but when I run over them again I see that 2-3kg/hp isn’t even close to modern piston engine (more like flathead hurricane engine from 1940´s jeep)
If we use figures from the comparison sheet on the Delta hawk website for Lycoming360 that says it weights 148kg we have power/weight ratio around 0.74kg/hp

So if the numbers for the Randcam being 0.34kg/hp is true, they got great advantage over piston engine, but they probably not even half way down the path and I doubt this will be the same number they end up with when reach the far end, if they ever will.

p.s. Nick I promise to be more precise next time, don’t want to be rotorrookie forever :{

rotorrookie,

This is a great thread, fear not, and thanks for your contribution to it! That was too good a snipe to pass up!

The data on the Deltahawk engines show them at the same weight as the equivilent HP gas engine, which is closer to what we could expect. The estimates about overhaul costs also seem very low, since these engines are turbocharged, which brings a pretty fine set of components into the game, despite the simplicity of the deisel itself.

The Mistral engines are much lighter, but they are rotary engines, and no rotory can achieve the fuel efficiency of a piston engine, so I would expect their fuel burn to be like a gas engine or perhaps a bit higher. I note that they don't publish any fuel figures (or did I miss them?) Also, rotary tip seals have not yet been perfected, I think (but have no recent data on).

If these engines can pass the cert tests, and show good reliability in the field, they can certainly liven up the field for our piston members!

Interesting differences between the Deltahawk and the SMA diesel engines.

First, the Deltahawk is a 2-stroke, while the SMA is a 4-stroke. This yields best BSFC figures of .39/lb/hp/hr for the Deltahawk, and .35lb/hp/hr for the SMA. The Deltahawk has a very strong torque curve, but you would expect that from a 2-stroke engine. That could be useful in a helo application.

The Deltahawk is a V4 while the SMA is a flat 4. This makes the Deltahawk more compact and lighter (it's also lower powered so it's lighter for that reason as well). However the Deltahawk is liquid cooled and requires a radiator, while the SMA is air cooled. I'm not sure how well a radiator on a piston helo would work out though.

Hi Everyone,

Currently in the automotive industry, diesel engines are now performing with better output than petrol engines.

The major manufacturers are building engines with 50Kw/Litre which is equivalent to most petrol engines (not racing engines). The difference is that the torque output is equivalent to a petrol engine almost double. This is achieved through the use of electronic injection and "common rail" technology.

An example of this is Peugeot's diesel in it's 407 line, it's 2 litre 4 cylinder engine produces 100Kw and 320Nm Torque @ 2000 rpm (236lbs/ft). That's equivalent torque to most 6 cylinder 4 litre engines!

Torque in both fixed and rotary wing is very important, that's why we have been using large capacity petrol engines for so long.

Fuel burn at maximum power/torque is around 25% below petrol engines, and would be significantly more compared to larger older designed air cooled flat 4's and 6's.

Although these engines (diesel) are very suited to aviation, especially their torque, reliability and the safety of a lower flash point (less likely to catch fire), it will be sometime before we see them in our rotorcraft, mainly due to the high cost of r&d and the low unit sales figures of helicopters (very low return on investment).

However I am sure it will happen. The same as hydrogen powered cars are our future, but we will not see them on the roads in the near future due to the large revenue return governments around the world derive from the oil industry.

In the Deltahawk performance sheet for the 200hp it says 7gal/hr at 65%(130hp) power and 11.2gal/hr at 100%(200hp).
The 300C with Lycoming 360 IO doing 12gal/hr at 85%(190hp).
I thought diesel engine main advantage should be good fuel efficiency, but you never get good fuel efficieny from a 2stroke specially at high engine output.

So to stay in tha fuel consumpsion range the Deltahawk would have to be 300hp at 100% to give us 195hp at65%.
How much will 300hp Deltahawk weight? maybe little more
And would it burn more fuel? likely
Maybe Deltahawk works well for small fixed wing but after all probably not as well for helicopters.
:confused:

Hi,

The whole weight issue is a bit of a blind statement - The performance of Diesels continues to improve - and weight will only be reduced in the comming years.

The Diesel Engine would be ideal for a Helicopter - because of what a diesel is good at - That is running at low revs all day!

Even the best Diesles will top out at 5000rpm -



Isn't the question therefore wheather or not we can design a suitable gearbox? Can we really have a diesel flat out at 4 - 5000rpm geared up enough without losing power for even an R22?

Just a thought

Rich

The actual issue is not comparing modern, newly developed turbo diesel with ancient, 30 year old technology gas engines, is it? If diesels just coming out of research can rival today's gas engines in weight, it is probably time for the gas engine manufacturers to redesign their engines to get more weight out and beat the diesels. Inherently, gas engines will be lighter, since the stresses of 9:1 compression are much lower than 17:1 of diesels.

I would expect that the same tools that made diesels approach gas engines (CAD design, close attention to thermodynamic processes, water cooling, rotory technologies) should let gas engines reduce considerable weight and widen the gap.

Competition is good, let the games begin!

How about this for a diesel????



Diesel Engine Link


Don't think it'd fit in your average R22





"Mad as a mooing fish!"

A big hurdle that has yet to be discussed here and can be hugely expensive to address is "torsional vibration".

An example - look at the difference in TBO and finite life of the TR gears in a 300C versus 500C. Exactly the same gearbox but massively lower lives when fitted to the piston machine.

Avgas burns slower than Jet or Diesel in a piston engine and the power spikes are lower and longer. With a diesel this while be a real problem to damp without introducing mass of some sort.

I always find it amusing when people think they can just put a car engine in an aeroplane and away you go. Has never really happened yet has it? Wonder why? The operating regimes are miles apart.

Well, it has actually. Take a look at Diamond Aircrafts DA40 and DA42 Twin. Powered by Thielert Centurion 1.7 Turbo Diesels which are modified Mercedes A-Class engines. http://www.centurion-engines.com/index.htm

The DA42 Twin crossed the atlantic on 72 gals of fuel! If that isn't efficiency I don't know what is. Maybe that particular engine isn't powerful enough for even the smallest heli, but Jet A1 burning pistons must be the way forward for aircraft like the 22 or 300

It might make them vaguely affordable (nahh, who am I trying to kid)

fly safe