Diesel aviation engines

[Rvrrat]

SMA has gotten their 230hp diesel certified, there are a number of other viable designs in progress.

With the impending demise of 100LL avgas what level of interest might there be in further diesel development?

 

[dav8or]

I've been looking at the sma engine for my RV8. Everything sounds wonderful but I havn;t seen the price. My guess is that it will be the deal stopper.

 

[BradG]

Last i heard, the price for the conversion for the FAA cert. version (wouldnt apply to the RV) was like $119,000 for the 182. Thats a hell of a lot of money for the small performance increase.

 

[Lrjtcaptain]

Embry Riddle had one that they put together. Was a C182 i believe...Saw it once, they taxied it down Clyde Morris Blvd to some convention while i was walking to class

 

[sstearns2]

.....

I don't think there is much of a future for diesel aircraft engines in the US. Jet A is about the same price as 100LL if bought in small amounts. Diesel engines also tend to be heavier than otto cycle engines.

Another thing to think about is that Jet fuel is heavier than 100LL, so one needs to convert gallons/hour to pounds per hour for a good comparison of fuel burn.

The diesel may have a future in Europe where av gas is heavily taxed and Jet fuel is conciderably cheaper.

I think 100LL will be around for a while, but eventually replaced with a fuel compatible with the current otto cycle engines. I also think we will start seeing auto fuel sold at airports in the future.

Scott

 

[cvsfly]

Re: .....

I don't think there is much of a future for diesel aircraft engines in the US. Jet A is about the same price as 100LL if bought in small amounts. Diesel engines also tend to be heavier than otto cycle engines.

Another thing to think about is that Jet fuel is heavier than 100LL, so one needs to convert gallons/hour to pounds per hour for a good comparison of fuel burn.

The diesel may have a future in Europe where av gas is heavily taxed and Jet fuel is conciderably cheaper.

I think 100LL will be around for a while, but eventually replaced with a fuel compatible with the current otto cycle engines. I also think we will start seeing auto fuel sold at airports in the future.

Scott

I think the 100LL market is in for a rude awakening. From all the news I have read in the last few years, 100LL is rapidly becoming a thing of the past. I think you will see 100LL continue to rise in price here (maybe if we secure Iraqs fuel reserves, we will buy a little more time for the Pipers and Cessnas). The national average for 100LL is more than JET A. Something like 1 or 2 refineries in N. America producing it and 1 other worldwide. With plans on ending production around 2010 and maybe having enough reserves for a few years after. There has been no real incentive to find a replacement fuel and the research and development is way behind. Older low compression engines will be able to use autofuel, but the high perf., high compression, turbo-charged engines are going to need the lead or figure out a way to substitute it. I think the diesel engine is promising and probably more so is the development of small turbine engines. The piston aviation market is small compared to the global fuel market. The times they are a changing.

 

[Redneck]

Getting off-topic, but when we call 100LL 100 octane, what measuring system is that? Motor octane, research octane, the average of the two (what we see at the gas station)? I ask because their are already unleaded racing fuels that are over 100 octane, at least averaging their motor and research octane ratings.

 

[310]

depending on who to believe, 100LL is either 115 or 130 on the scale that you see on auto gas pumps.

diesel engines are usually heavier but diesel engines have better specific fuel consumptions than gasoline burners

It is measured in pounds per hour per horsepower

A high compression ratio non turbo engine like a Continental IO-470D has a specific fuel consumption of about .43 lbs per hour/horsepower.

An average for 100LL burners is about .5 or .52 .

Diesels are more like .4 or .38 ---- so you don't have to carry as many pounds of fuel for a given trip. If the airplane is anything but a small two seater, the decreased fuel weight more than offsets the extra engine weight and TBO's are higher on diesels.

(jet A is heavier per gallon than 100LL but I am talking about horsepower per pound of fuel)

 

[sstearns2]

.....

Hello all,

I get an SFC of 0.4 for an engine making 75% of 200HP at 10 gal/hr. We've all flown behind IO-360 and gotten this fuel burn. An SFC of 0.3x is possible with electronic ignition or better yet FADEC. I beilive the O-470 is one of the least efficient aircraft engines out there.

Be careful about saying that the TBOs are higher on diesels as there are so few flying. Noone is really going to know what the real life TBO is until there are a lot flying in the public despite what the manufacturer might claim.

I believe the large turbocharged twins will give way to turbine singles like the PC-12, TBM-700 and Caravan and engines below 300HP will be pistion and above will be turbine.

How much do the aero diesels that are being developed weigh?

I don't think 100LL will rise in price much. The price has been very stable for the last 10+ years even as mogas fluctuated wildly. Jet fuel is cheaper that avgas when purchased in large quantites. I 'pay' about $1.10/gallon to put 250 gallons onto a brasilia at LAX, but if I want 30 gallons for my Lancair in Camarillo I'll pay $2.50 gallon and I can get 100LL for $1.99/gallon at the self serve pump. Ever seen a self serve JetA pump? I've seen only one, so your stuck paying a premium for a line guy to pump your gas. Also most of the smaller airports don't have Jet A, so you may be forced to fly out of your way to get fuel.

Scott

 

[cvsfly]

Re: .....

I don't think 100LL will rise in price much. The price has been very stable for the last 10+ years even as mogas fluctuated wildly. Jet fuel is cheaper that avgas when purchased in large quantites. I 'pay' about $1.10/gallon to put 250 gallons onto a brasilia at LAX, but if I want 30 gallons for my Lancair in Camarillo I'll pay $2.50 gallon and I can get 100LL for $1.99/gallon at the self serve pump. Ever seen a self serve JetA pump? I've seen only one, so your stuck paying a premium for a line guy to pump your gas. Also most of the smaller airports don't have Jet A, so you may be forced to fly out of your way to get fuel.

Scott

You are lucky. That Brasilla at LAX at $1.10/gal, is that an airline at volume airline discounts? Prices 2 years ago jumped quite a bit. You definatly have to do your shopping these days. At major chain FBOs without any discounts the price is close to $3.00/gal. People operating Tprops and Jets typically aren't the type to pump their own. Ever seen an AVGAS spill compared to JetA? Of course smaller airports (< 3500') don't have Jet A - not enough customers can use those runways to make it worthwhile. Supply and demand. I'm suprised Kalifornia hasn't outlawed AVGAS already.

 

[310]

sstearns2,
I mentioned the IO-470D, not some of the carb version of lower compression ratio, .42 or .43 for the IO-470D.(260hp)

 

[MSNFlier]

what about small turboprops??

Just a thought (and I am BY NO MEANS an engineer of any kind): with the advent of jet engines which weigh just 85 pounds but develop 770 lbs of thrust like the Williams EJ-22 developed for the Eclipse (and yes, I know it is having some teething pains), is there a place for a small turboprop engine dervied from something like that, instead of a diesel, or no?

I would think that the initial weight issues are addressed because the EJ-22 engine itself is so light, but would the other mechanical requirements to make it into a turboprop make it so heavy or complex as to be impractical?

As I said earlier, I don't know much about the engineering side of making something like that happen, but I'm curious whether others with more knowledge about these kinds of issues might have some thoughts?

Interesting thread.

 

[CRJ200FO]

Re: what about small turboprops??

Just a thought (and I am BY NO MEANS an engineer of any kind): with the advent of jet engines which weigh just 85 pounds but develop 770 lbs of thrust like the Williams EJ-22 developed for the Eclipse (and yes, I know it is having some teething pains), is there a place for a small turboprop engine dervied from something like that, instead of a diesel, or no?

I would think that the initial weight issues are addressed because the EJ-22 engine itself is so light, but would the other mechanical requirements to make it into a turboprop make it so heavy or complex as to be impractical?

As I said earlier, I don't know much about the engineering side of making something like that happen, but I'm curious whether others with more knowledge about these kinds of issues might have some thoughts?

Interesting thread.

Actually, the main problem with a turbine engine on a light plane isn't the weight, it's the cost. Turbine engines are extremely higher in price than a piston engine, even if it is diesel. There are people that take their light singles and pay to have turboprop conversions done, but they usually end up spending half a million to have it done. Even the Eclipse, which is supposedly going to revolutionize light aircraft, costs in the neighborhood of $900k. For your average cessna or piper owner, turbine will not be a possibility for many years to come. The engine costs more than their entire aircraft costs.

 

[cvsfly]

A couple of years ago at the NBAA convention Williams had a display of all their engines including an experimental prototype turbo-prop engine. Measured about 3' long by 8" round and weighed 80 lbs. I think the we will see a reasonable/affordable turbine engine in the near future.

 

[DIRT]

Avgas

I guess when they stop selling Avgas I'll just get a really big rubber band for my C150.........

 

[310]

correction to previous post

According to zoche's and sma's webites the sfc of their engines is better even than I posted before. At cruise power zoche claims a sfc of .346 lbs per hour/horsepower and sma claims 215 gr/kwh average which converts to .353 lbs per hour/hp. (1 kwh = 1.341 hp) ( 1 lb is 453.59 grams)

These sfc are not possible in a 100LL as far as I know.

 

[sstearns2]

EJ-22 and zoche engines

Hello all,

The EJ-22 is an interesting engine. Williams developed it beause NASA gave them a tremendous amount of money. They claim a weight of 85 pounds, but they put everything possible under airframe weight. Things like fuel pumps, hyd pumps, stater/gens, etc. As far as efficiency and price are concerned, we'll just have to wait and see. I hope they can make it happen, but I think they told NASA whatever they wanted to hear to keep the cash flowing.

I'm sceptical of Zoche's claims. They've been working on thier engines for many years and have yet to actually sell an engine. Certification seems to always be 'about a year away'. I want to make a webpage about my new tubro-stearns cycle engine that makes 300 HP at 7 gallons/hour and see how many deposits I can get.

Scott