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05-06-2013, 11:55 PM
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Join Date: Sep 2010
Location: IL
Posts: 18
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JP,
You have my respect and admiration. Thank you for sharing.
I understand your frustration. Clean-sheet engine design and production can't be easy. I'm a +1 to all those who have been keeping DH in the corner of my eye for the last 5-6 years and am glad to hear the project is not dead and additional info is pending.
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05-09-2013, 09:19 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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This thread has been moved to the "Alternative Engines" forum, for later ease in locating it.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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05-10-2013, 03:50 AM
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Join Date: Apr 2007
Location: Norway, Stj?rdal
Posts: 598
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Quote:
Originally Posted by rv6ejguy
Thanks. The weight isn't bad at all, especially the 2nd figure.
The SFCs on the site puzzle me. It looks like .43 there in the cruise range which is higher than a Lycoming, variously listed at between .39 and .42, depending on mixture and model. I know Jet or Diesel fuel is heavier per gallon than Mogas or Avgas but where are the big fuel flow savings coming from you mention in your site? How can you have lower fuel flows when the SFCs are not as good?
The big Contis are around .375 LOP in cruise.
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Maybe you have hit the nail straight on the head here. The SFC on a normal modern 4 stroke TDI is much lower than this, typically 0.3 or lower. Maybe this is what you have to pay for piston ported lay out? The Wilksh has overhead valves just like the big marine two strokes. What is the SFC on the Wilksh?
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05-10-2013, 07:15 AM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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Quote:
Originally Posted by SvingenB
Maybe you have hit the nail straight on the head here. The SFC on a normal modern 4 stroke TDI is much lower than this, typically 0.3 or lower. Maybe this is what you have to pay for piston ported lay out? The Wilksh has overhead valves just like the big marine two strokes. What is the SFC on the Wilksh?
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The WAMs stated SFC is not that good either (stated at .43-.45 in cruise- again- about the same as a Lycoming running lean) and in fact people with O-235 and IO-233 Lycomings report pretty similar fuel flows and speeds (around 5.25 gph at 65% power). We really should be measuring weight of fuel burned not volume in operating comparisons. When max range is considered, the higher density of diesel or jet fuel is an advantage if you have the gross weight capability to lift it all.
2 stroke diesels have good power to weight ratios for aircraft but the 4 strokes have better SFCs.
The thing with the Deltahawk figures is that their specs don't make logical sense which is why I asked for the clarification. I questioned another designer who was claiming .26 SFCs (ludicrous for a SI engine) on an LS1 powered design and was simply met with anger and no explanation. Lots of questionable SFC claims out there.
Last edited by rv6ejguy : 05-10-2013 at 08:15 AM.
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05-10-2013, 08:13 AM
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Join Date: Apr 2007
Location: Norway, Stj?rdal
Posts: 598
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Interesting. But the low SFC of modern 4 stroke diesels have happened only during the last 10-15 years. I think a traditional (old school) diesel is considerable higher. But the density of diesel fuel is much higher than gasoline, about 10%, so a diesel will use less litres per km.
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05-10-2013, 12:29 PM
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Join Date: Mar 2005
Posts: 182
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Quote:
Originally Posted by rv6ejguy
2 stroke diesels have good power to weight ratios for aircraft but the 4 strokes have better SFCs.
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Both the WAM & the Deltahawk have indirect mechanical injection for simplicity & easier certification. Direct injection especially with electronic control would probably improve the SFCs of the 2-strokes.
__________________
Dave Boxall
RV-9A / Wilksch WAM-120 diesel. Flying since April 09
Bath England
=VAF= membership dues paid April 2017
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05-12-2013, 09:31 AM
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Join Date: Mar 2009
Location: Boulder City, NV
Posts: 165
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A sincere "thank you"
[quote=J
I've enjoyed talking with most of you. Like all pilots, we come in all varieties, ...most better than others.... And "others" tend to make mistakes overestimating their importance and attention span of those they talk with. Those are the ones we tend to watch closely in any cockpit.
[/QUOTE]
JP,
Welcome to VAF! Unfortunately you've found that there are some on this forum who are unfriendly towards aerodiesels. They'll say that it's because you don't give them enough facts - but that's not really true. I've provided solid data that shows the WAM two stroke diesel measures up to it's Lycoming equivelant in every way, while being considerably more efficient. I've even provided side-by-side, same day-same- way fly-off comparisons (written by Van's head engineer himself) between the diesel and Lyc. powered RV9's. The WAM fleet has 1000's of trouble free hours. But this forum always seems to gravitate to a "your (fill in the blank)-will-never-be-as-good-as-a-Lycoming" forum.
I look forward to the day when I can personally thank you for your vision, patience, and investment in developing the DH aerodiesel. Few people have the courage or the means to embark on such a project. Few understand what it takes to develop a new engine and make it work.
I assure you that there will be plenty of buyers for the DH once it is available. I'm one of them. Most of the GA world sees the writing on the wall and is looking forward to seeing sensible lightweight Jet-A powered aircraft become more mainstream. So don't give up, no matter what the naysayers throw at you!
Kurt Goodfellow
RV9 WAM 120 diesel, 440 hours, zero problems.
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05-13-2013, 11:58 PM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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Quote:
Originally Posted by kgood
JP,
Welcome to VAF! Unfortunately you've found that there are some on this forum who are unfriendly towards aerodiesels. They'll say that it's because you don't give them enough facts - but that's not really true. I've provided solid data that shows the WAM two stroke diesel measures up to it's Lycoming equivelant in every way, while being considerably more efficient. I've even provided side-by-side, same day-same- way fly-off comparisons (written by Van's head engineer himself) between the diesel and Lyc. powered RV9's. The WAM fleet has 1000's of trouble free hours. But this forum always seems to gravitate to a "your (fill in the blank)-will-never-be-as-good-as-a-Lycoming" forum.
I look forward to the day when I can personally thank you for your vision, patience, and investment in developing the DH aerodiesel. Few people have the courage or the means to embark on such a project. Few understand what it takes to develop a new engine and make it work.
I assure you that there will be plenty of buyers for the DH once it is available. I'm one of them. Most of the GA world sees the writing on the wall and is looking forward to seeing sensible lightweight Jet-A powered aircraft become more mainstream. So don't give up, no matter what the naysayers throw at you!
Kurt Goodfellow
RV9 WAM 120 diesel, 440 hours, zero problems.
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I think WAM has a lot to be proud of compared to every other aero diesel manufacturer to date. They have delivered a reliable, weight competitive and cost competitive aero diesel (in a reasonable time period and on a fraction of the budget too), something that Zoche, Thielert and SMA didn't. Call me skeptical when it comes to big companies and drawn out development in this field.
DH has missed the boat of cost by a wide margin and they have no track record of performance and reliability to date. Assuming they demonstrate equal or better reliability compared to Lycomings, they will still never save money overall unless the purchase price comes way down. $30K buys 5000 gallons of 100LL or 8000 gallons of unleaded.
I'm not trying to be unfriendly here, just get some explanations about costs and SFCs. WAM had this sort of info available long before they delivered the first engine as you'd expect from a serious, reputable manufacturer. In the past, reluctance to answer technical questions about new engine designs has almost always shown that something was not so impressive and did not stand up to scrutiny. Potential buyers are going to want to know this stuff I believe. When you have all the answers and it is the truth, your credibility in the eyes of customers just went way up. I am sure that anyone can see here, including DH, that they are a bit low on credibility at this point after all the years and announcements coming and going. They can start turning that the other way with some straight answers.
Finally, it is ok to like Wankels, Subarus, Lycomings, diesels or whatever you want. There are advantages and disadvantages to each. I believe you should fly with whatever turns your crank so to speak. However the numbers speak for themselves and we know from a poll here on VAF that several RV9/As with O-360, O-320 and O-235 power running lean and with partial carb heat, post FF/TAS numbers similar or even better than the WAM powered ones. http://www.vansairforce.com/communit...v9+performance This is despite a 10% BTU deficiency per volume fuel. No magic here since the DH and Lycoming have similar SFCs in cruise which is why the question of SFCs is important.
In the Van's test, the WAM was inferior in both ROC and speed to the O-320, despite being turbocharged and used more energy to complete the first performance flight even though it was going slower. As I have said before, it is more comparable in weight and performance to the O-235. The article also stated that the WAM was allowed to dictate the cruise tests profiles to its best advantage where it came out on top by a fair margin so this is no surprise perhaps and we are not told if the O-320 was running LOP or with partial carb heat which makes a fair difference in FFs. There were other factors of course, different props, one aircraft was a taildragger and one an A model with consequent weight and drag differences and at the same time the WAM -9 probably could have benefited from a cleaner cooling system too.
This test did however allow us to see a comparison and I found it very interesting technically. Thanks again for having the confidence in the engine to do this, I love articles like this.
The point I am trying to make here is that while we might believe something is clearly better in all respects, impartial scrutiny often shows otherwise as I found out in my side by side with an O-360 RV6A also featured in Kitplanes years ago. I couldn't deny that the Lycoming was superior in almost every performance test below 12,000 feet because the true facts were right there for me to see. Enthusiasm should be tempered by reality and engine choices determined by your mission and preferences. We all have different important criteria so there is no one "right or only" engine choice for everyone.
I'll stand by my earlier statement that the markets for the DH at its current pricing will be restricted to the 3 types of buyers for now. If aviation gasoline disappears at airports and is replaced only with Jet A, I am going to be in the market for an aero diesel too and I hope something like a 180-200hp WAM is available by then. I have less confidence that DH would be able to meet my price point. Diesels will be an important part of the future of GA, no doubt about that but I believe there will be unleaded avgas in the not too distant future and there will still be plenty of SI engines flying too, just like in the automotive world where there are also two choices.
Last edited by rv6ejguy : 05-14-2013 at 06:11 AM.
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05-15-2013, 06:54 PM
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Join Date: Apr 2007
Location: Norway, Stj?rdal
Posts: 598
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Quote:
Originally Posted by rv6ejguy
I have less confidence that DH would be able to meet my price point. Diesels will be an important part of the future of GA, no doubt about that but I believe there will be unleaded avgas in the not too distant future and there will still be plenty of SI engines flying too, just like in the automotive world where there are also two choices.
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Maybe diesels will be more plentiful for larger certified aircraft with 1000+ flight h per year, but for smaller and uncertified aircraft they are too complex, too heavy and becomes too expensive. Besides, all the way from 30 to 200+ hp there are new engines available that runs on any autofuel, even with ethanol/methanol, so the need for a single replacement for 100LL is becoming increasingly irrelevant.
It is really rather backward trying to formulate a fuel to run on 50-60 year old engine technology when modern engine technology have since long moved way past the need for such a fuel.
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05-15-2013, 09:15 PM
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Join Date: Mar 2009
Location: Boulder City, NV
Posts: 165
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Too complex? Too heavy? Too expensive?
Quote:
Originally Posted by SvingenB
Maybe diesels will be more plentiful for larger certified aircraft with 1000+ flight h per year, but for smaller and uncertified aircraft they are too complex, too heavy and becomes too expensive. Besides, all the way from 30 to 200+ hp there are new engines available that runs on any autofuel, even with ethanol/methanol, so the need for a single replacement for 100LL is becoming increasingly irrelevant.
It is really rather backward trying to formulate a fuel to run on 50-60 year old engine technology when modern engine technology have since long moved way past the need for such a fuel.
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The current 4-stroke aerodiesels are too heavy, complicated, and expensive. But it does not have to be that way. The Wilksch in my RV9 is lighter, extremely simple, and no more costly than its equivalent Lycoming. And it's much cheaper to fly. The DH is even simpler.
These "new engines" you refer to, that run on auto fuel, are also expensive, and some are pretty complicated, definitely more complicated than a WAM, IMHO.
I agree that it's backward to develop a new fuel to replace avgas, but the current fleet of traditional engines is quite large and many can't survive without it. I agree with Ross, the 100LL replacement will be developed, but there is no question that it will be very expensive, as if 100LL is not expensive enough already (at most airports I've been to lately, it's almost $1.00/gal more than Jet A).
I'm not saying that diesel / JetA is the final answer to GA's problems, but it's one of the answers. It sure has been good for me.
Kurt Goodfellow
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