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AC Aero (Higgs Diesel) E-330 Hawk Engine

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majuro15

Well Known Member
AC Aero E-330 Hawk Engine

Fair warning, this is a long post!

As some may have noticed, I?ve been interested in other than Lycoming options for my RV-10 build since I started six years ago. My mission, to which I?m building my airplane to achieve, is to have an efficient high performance and luxurious cross country cruiser while having flexibility to still do a sunset treetop flight from time to time. I?ve always been interested in advancement of technology and maximizing performance and efficiency. I am building a four seater to take my wife and friends/family along for the ride, so dependability and reliability is important to me as well. I am not afraid of the ?experimental? in experimental aviation, so I recognize that there is a middle ground on all of the aforementioned requirements and my middle ground may be different than others?. With that being said, in the interest of sharing information with others and educating myself along this project, I would like to share my experience with anyone who is interested in following along. I hope this can be an interactive and positive topic and will absolutely avoid anyone trying to slam the concept just because it?s not what they would do.

I?ve watched the Turbine Solutions Group, Delta Hawk, Continental, Auto PSRU, Adept Airmotive, and others all with excitement and interest but none have really gone beyond a prototype or a test stand. ACE caught my eye about four years ago with their AX-50 cylinders and ACE-540 engines. The cylinders were a new design tailored to performance and the ability to use MOGAS without all of the problems of the traditional Lycoming design. I liked it because it was enough of new technology and offered great performance / efficiency but still retained the tried and true design from Lycoming at its heart. When I contacted Andy Higgs last spring to discuss options and an order, we got side tracked with a new project he has been working on for some time. I was instantly hooked.

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The newly launched Higgs Diesel E330 Hawk by AC Aero is a clean sheet, multi-fuel, spark ignited piston engine. While it is primarily meant to burn Jet A, a variety of fuels may be used with minimal performance degradation and no hardware/software changes required. The V4 design uses a modular architecture which is shown in the development of the larger E1000 V12 Condor design. A V8 version is also planned. The E330 Hawk will produce ~350 horsepower normally aspirated or ~500 HP turbocharged. It uses a unique stepped piston design and interconnected cylinders to help compress the intake air and scavenge exhaust gases. The two stroke cycle is designed to burn cleaner and more efficiently than other traditional diesel engines. This allows for lower parts count, simpler drive systems, and reduces vibrations. The crankcase encompasses the geared prop drive, accessory drive outputs, and uses a traditional pressurized lubrication system. The engine is liquid cooled using a closed loop coolant system as well as an oil cooler. It will be ~350 pounds including cooling system and accessories. Based on scaled test power plants, the Hawk will produce 275 HP at 80% power burning 8.5-9 gallons per hour. Andy is using a custom mapped ECU and closed loop systems to have a power control lever along with a prop control, eliminating any fuel mixture input from the pilot. He anticipates running a three bladed MT propeller on the non-turbo and a five bladed MT-5 on the turbo versions.

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I?m working on creating a page on my build log with more information from AC-Aero so folks can learn and follow along, so I?ll update that as I get more information. You can checkout Andy's website at http://www.ac-aero.com/. I also have a PDF document with a lot of technical information on my buildlog here. Andy's been posting some updates on his FaceBook page as well that folks can look at even without a FB account (I believe).

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So, back to the story, Andy asked me if I had been following his project and we started talking details. To me, it fits a RV-10 perfectly! It is a bit more powerful than a 540, but not crazy strong. It?s got great performance, fuel flexibility, simple controls, and lightweight design. I see it maximizing the performance, range, and payload of the RV-10 beautifully. As I got more and more details, I fell harder in love with it. We discussed mission, timelines, and expectations and it all seemed like it was a perfect fit. The only question left was will it work???

That?s a big, unanswered question.

I?ve been working with Andy for over a year now on the integration of the engine and we are making great progress. A few other 10 builders have jumped on board to assist even though their projects are not as far along as mine. With Andy?s help, we?ve been able to continue our builds with zero modifications needed until an engine is in hand. This was important to me because I already have a quote for a phenomenal 540 engine that will more than meet my needs. I didn?t want to get to a point where I was too far committed to an engine that I don?t have and is unproven. I?m very happy to say that thus far, it?s gone very smoothly. I already had a fuel return line built into my plane and until we need the engine mount and are ready to hang the engine, I won?t stray from Van?s plans to be able to bolt on a 540 should plans change. With that being said, I am fully committed to the Hawk engine and hope to help prepare a firewall forward package for others to add to their aircraft.

While the engine is now formally launched, there are a lot of details still confidential. I can say that the first batch of engines are being assembled now for an OEM customer in the US, with my engine being one of that batch. He has also delivered two of the V12 versions which are undergoing installation on air-frames now. He has been testing a scaled down version of the engine using the same design principles for several years with excellent results. The production version of the E330 should begin dyno testing in the next few weeks, as manufacturing has gone very smoothly with only a few minor component tweaks. Currently, we are working on cooling system and engine mount design with good progress. I already have a Show Planes cowl and will be modeling up the needed modifications with Andy?s guidance. We are targeting an April-May delivery of my engine and my goal is to be flying by the end of the year.

So, long post but hopefully entertaining and intriguing for those reading it. I?ll be happy to try and answer questions that are asked and share the information / progress updates as I get them. I will disclaim that I am not a partner, representative, or salesman for Andy or AC Aero, just a customer who is interested in helping and sharing while getting what I want!

Stay tuned as I slug my way through the ?alternate engine? story to hopefully a very happy ending!
 
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Very cool Tim.

I met Andrew at Reno last year and was impressed with the engine design and him. He strikes me as a very clever guy.

Has a prototype of the engine you plan to use completed dyno testing yet and what sort of hours and power settings has it completed if you can tell us?
 
Very Cool. Hopefully this works and is a good alternate engine choice.

Lots of unanswered questions, but hopefully we learn more over the next year or so. Looking forward to seeing more on this new engine design.
 
I contacted Andy several times via email and never got a response. Thanks for the excellent information on the engine. I think you need to review your fuel burn numbers, they don't match the best economy bsfc in the literature.

I wonder how the top rings get lubrication. Diesels work well down to A/F maybe 18. Meaning - it will be very challenging to meet SFC and power with reasonable temperatures at altitude if remaining naturally aspirated. Well, maybe, depending on the BMEP expected, do we know the displacement? The true displacement from port closing? So many questions.

Beautiful design work, just captivating.
 
Ross, yes he has had several prototypes running on dynos, but no numbers that can be released as of yet. He has over 4000 hours on the scaled versions and is currently testing one to destruction while experimenting with components on a few others to max out performance. His background was a career in Formula 1 engineering, so yes he's a pretty smart guy! He knows way more than I ever will about engines so I quickly get lost in the technical details.

The fuel numbers are just estimates and could be off. We won't have an accurate number until dyno testing. We'll be sure to post them as soon as we can. I'll get a displacement number for you soon, I thought I had it written down but I can't find it. He's currently working the cooling setup as he knows how many BTU/hr we need to shed so processing the formulas to figure out radiator size and air flow.
 
One of these days, someone will offer a viable alternative to the Lycoming. Let's hope Andrew's engines will be that one.

I'm interested in how a non-turbo 2 stroke diesel will work at altitude and what the BSFC will really be like as typically, they are no better than a 9 to 1 Lycoming running LOP with a good EI system. I don't buy the .204-.216 figure.

Has Andrew discussed cost and proposed product support structure in North America?

Exciting stuff, looking forward to updates as the story unfolds.
 
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As I said on facebook, I REALLY wish this would have been an option a few months ago.

Very excited about this engine!!
 
As I said on facebook, I REALLY wish this would have been an option a few months ago.

Very excited about this engine!!

Considering they are just now heading to the dyno with the first full-size unit, it's unlikely to be a viable option for some time yet. I'm certainly hopeful it's ready for market before I start building a 10 in a couple years.
 
One of these days, someone will offer a viable alternative to the Lycoming. Let's hope Andrew's engines will be that one.

I agree. Major respect to Andy for tackling this difficult challenge. I, for one, hope he's successful.
 
The newly launched Higgs Diesel E330 Hawk by AC Aero is a clean sheet, multi-fuel, spark ignited piston engine. While it is primarily meant to burn Jet A, a variety of fuels may be used with minimal performance degradation and no hardware/software changes required.
I'm intrigued about the "spark ignited" (in fact 2 spark plugs/cylinder). I looked on the website but didn't find any explanation. Most diesels I am familiar with may use a glow plug to preheat the combustion chamber during starting, but when running are "compression ignition" (heat of compression sufficient to ignite the fuel sprayed into the combustion chamber by the injection system).

Andrew?
 
Where did you get the .214~2.16 figure from? as it was certainly not me or my company. The current engines have proven a BSFC of 0.398

Andrew

From Tim's post: "Based on scaled test power plants, the Hawk will produce 275 HP at 80% power burning 8.5-9 gallons per hour."

I saw the .398 reference on your site so questioned the discrepancy between the 2 figures. .4 is about the same BSFC as a Lycoming running LOP with proper timing advance.

.398 would mean around 16.6 gph at this hp.
 
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From Tim's post: "Based on scaled test power plants, the Hawk will produce 275 HP at 80% power burning 8.5-9 gallons per hour."

I saw the .398 reference on your site so questioned the discrepancy between the 2 figures. .4 is about the same BSFC as a Lycoming running LOP with proper timing advance.

.398 would mean around 16.6 gph at this hp.

Yep, that was why I suggested Tim recheck the information. Not stellar BSFC for a diesel, but if the weight is competitive, then it could be really attractive for markets other than the US/Canada.

Stepped piston, 2 stroke designs are not good for low friction or expansion ratio but, it is a clever way to eliminate a blower, lessen the thermal load on the pistons, and get better power density with lower PCP. The aero application makes the abnormal tradeoffs (for ground based applications) worth investigating.

I do wonder why there is no provision for turbocharging. That is well documented to improve power density and SFC. That would apply to this engine as well, if if the PCP increase can be accommodated. That piston pin looks way too small for any boost, but could be a non-current drawing.
 
Interesting

Popping corn and settling in to watch this show. Could be a long one, but I hope it turns out better than the last several. Please keep us posted!
 
Although the moniker is the Higgs Diesel, my engine is not actually a compression ignition engine. I burn JET A or diesel fuel and it is ignited by spark plugs. We will never have a BSFC reaching a traditional "Diesel". Our target market for the V12 was a replacement for the PT-6 turbo prop where we are very, very competitive on fuel burn. Hope this gives a little clarity to the "diesel" in Higgs Diesel.

Andrew

That clears up the confusion. Thanks Andrew.
 
What is the price point for this engine? I?m building a moose with a 400hp M14P, but the ability to burn multi fuels is what interests me in this engine.
 
Captain Huneycutt

I appreciate the information you've presented here- I too was very interested in the monolithic cylinders for my 540 build so I'm somewhat familiar with this impressive company. However, your OP has me scratching my head concerning the performance requirements that led you down this path. It seems your mission requirements are in conflict and I'm wondering if you can clear that up. On the one hand you are looking for a reliable, efficient people mover for your family; while on the other hand you are looking to advance the state of the art. Flying your family around in a testbed for a clean sheet powerplant is a big conflict!

As you know, the venerable Lycoming architecture has been around for a while, yet even with its sometimes crude design elements (cylinder head and port design just one example) it will still produce some impressive BSFC figures in factory trim. I have produced data that shows this already enviable baseline can be significantly improved with electronic ignition with an optimized map, and others have shown that optimized, individually tuned injectors (as developed by SDS EFI, demonstrated by Dave Anders) can help more, and of course there are plenty of tuned induction, exhaust and cylinder head options to add even more. At the end of the day there are a host of proven options to enhance the already impressive efficiency of the stone axe reliable 540 architecture. A competitor has its work cut out for it to overcome the long standing attributes of the legacy engine.

So with all that said, I assume that you performed some form of performance attribute trade study that led you to the new engine. Can you share the top 5 with us? What does this new engine offer (to you) as a realistic performance improvement over an optimized 540?

And before anyone thinks I'm "bashing" the new engine, I'm not. I very much would like to see this company offer a viable alternative to the existing product offerings. This market could use some competition.
 
Andy has a target of $55K for the NA version and $74K for the turbo version. Of course, that may change, but it may stay the same.
 
Mike, good point on my interests. Some would argue flying my family in a small plane is in itself dangerous and unwise. Some would say single engine ops over mountains at night is rediculoulsy stupid. Each is different. I will certainly ensure that adequate testing has been performed before I take to the skies with this engine and will take a cautious approach to putting others in the aircraft with a new engine. While there are plenty of thousands of Lycomings flying around, they still fail as well, so there is some inherent risk with any powerplant. I do see your point though, and it's a measured risk that I will mitigate to my standards before putting other people in my aircraft. Good point to bring up!

I agree with you that competitors have their work cut out for them. It's one of the reasons I believe that so many have come and gone without success. It's hard to compete with a proven, even if it is outdated, design. I'm not sure Andy will be different. Only time will tell. I believe he will be but who am I? (I'm awesome, that's who - Just Kidding) My "backup" primary powerplant will be an Aerosport built 540 with SDS and some other nice goodies for just the reasons you pointed out.

But, I'm still pushing for the V4 as my dream engine for a few reasons. One is the power. I'm considering doing the turbo version to take advantage of power at high altitudes as a cross country machine. I am NOT thinking I'll fly at 200knts! I understand I'm building a RV 10, not a PC-12. But, I am putting AC, oxygen, nice interior etc. and would like to have a little extra power available should I need it. The fuel numbers that were discussed and projected are lower than the 540 (although those have to be proven as others have mentioned a discrepancy on the numbers). I like the idea of running Jet A since we want to travel the Caribbean and Mexico, were 100LL is expensive or not available. The TBO is on condition as well and I like the architecture of the drive train with a simplified intake/exhaust system and geared prop drive all designed into the case with proper lubrication and no belts! The ingenuity is sexy to me as well and the idea of the 5 bladed prop is pretty cool factor (I know, I'm a dork but can you blame me?).

Finally, it's just something unique and new. This is experimental aviation and that's why I'm interested in building my own plane. I could go buy a SR22 and be flying tomorrow, but it's not what I want. I'm building what I want! I encourage others to do the same!

Realistically, there is still a lot to prove. Andy's got some great designs and parts on hand and a lot of funding and work into this project. For me, it's not proven yet and I don't have an engine yet. But one day, a long time ago, Lycoming 540's were brand new!

All good questions Michael, thanks!
 
Thanks Tim. Appreciate the time to respond. Reading between the lines it seems that the primary driving factor for you is the "experiment" of advancing technology. There is nothing wrong with that, but I'd caution you to be honest with yourself about justifying your decisions. I've worked in aerospace a long time, and even veteran design engineers can "fall in love" with an idea and then back into the requirements to justify that cause. Thats why we have peer reviews. In your case it seems you are envisioning a rosy future with a perfect end product - but it is a near certainty that you have a long, hard road ahead before you are whisking your loved ones to the Carribean.

And from a more technical standpoint, loading up an RV-10 with lots of bells and whistles, then hanging 500 turbo'd horses on the firewall is not something to be taken lightly (no pun intended).

Best of luck and I really hope it works out like you envision.
 
Andrew comes from the F1 world where there is a high level of structured testing preceding the introduction of a new engine. The propeller/ gearbox and TV adds another element to be tested here so not only should the engine be tested at MCP for many hundreds of hours, but also over the entire rpm and load range as the auto OEMs do these days to uncover anything which may be lurking. Finally, at least 500 hours of flight testing over all regimes and rpm/ load points would have to be done. This is all time consuming and expensive.

We do have to remember that F1 credentials in themselves don't guarantee a successful aero engine as we've seen from WAM (ex Ilmor) and SMA (Renault Sport) which had multiple problems after introduction which should have been caught with a proper testing program. In the end, only a bunch of reliable, actual flight time validates the design success of an aero engine.

I'm hoping the Higgs engines get there and offers folks a viable alternative to Lyconentals. It's a very innovative design. The 2 stroke offers a big power to weight advantage over 4 stroke designs, if it can be made as reliable.
 
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Mike, good advice that is appreciated. I like to think positvely but realistically. I know there will be teething problems and I hope to document those just as much as the successes. I think that's important for others to see as well.

My 10 won't be the heaviest out there by any means either, but it's certainly not the skinniest. Wise words as well.

To Ross's point lots of testing needs to happen before flight and even then a good flight test period to prove long term reliability. With a few folks on board with 10 projects along with an OEM that will have a lot of engines going soon (if targets are met), those operational hours will climb quickly.

Again, only time will tell and if I'm not comfortable with it personally, I've already got the color picked out for my 540 ;)
 
New data - exciting and sometimes confusing!!

Bill I sent you a reply asking you to clarify your comment about the "poor" frictional issues. I have just come off the dyno with a client and in fact the the FMEP is lower than any engine we have tested to date. Whilst the pumping piston does increase pumping losses and increase friction, this is offset by the fact that these engines do NOT have any valve train rockers or cams to drive.

Andrew

That is outstanding, Andy, the modern rings must be part of that equation too. I was speaking from a generalization, and that is always dangerous to compare to real life. Yes, the pumping losses are higher, not much available to avoid that, but elimination of a blower for starting to force the beginning of the process is a huge weight saving not to mention friction and pumping losses for some operating conditions. Then there is that thorny heat of compression to deal with . . .

Regarding the expansion ratio, my comment was based on many simulations with piston port valving. (I don't recall the stepped piston design specifically) Where it takes some physical stroke to uncover the port on the expansion stroke. Without 3000 psi PCP capability it is not likely to eat much efficiency, but will definitely have its effect. It might be an advantage for turbocharging, though recapturing the blowdown energy.

Does your stepped design allow tailoring the intake timing to allow a shorter stroke than the exhaust stroke? I am not sure that is even possible as blowdown pressures on 4-strokes can be 50 psi.

All this is moot now with test data coming in. Decades ago I did a tour of Hino, Isuzu Diesel, Toyota, and Mazada, then later worked with Isuzu quite closely. All on diesel designs for low particulate emissions. There are some outstanding diesel engine design engineers close to you!!. The Hino guys were really impressive, as was the designer at Isuzu (Duramax), very free thinkers. All long gone by now, but surely succeeded by people just as capable.

I assume you are using common rail fuel injection? It is the holy grail for multi fuel capability with its ability to rate shape the injection charge and do a pre-injection for control of cylinder pressure rate-of-rise issues.

Best of luck with development, and keep us posted on results. My PM-email works here.
 
Just following up to say I'm interested and I love the development.

I'm soon going to throw a post up in an appropriate forum about my history and why I'm here, but I truly am rooting for a viable alternative!

Teej
 
Just following up to say I'm interested and I love the development.

I'm soon going to throw a post up in an appropriate forum about my history and why I'm here, but I truly am rooting for a viable alternative!

Teej

Welcome aboard, Thomas!
 
I love the new tech and innovation and wish everyone involved the best of luck.

One quick point of reference. A comment was made about 100ll in Mexico.
It just so happens that for the past two weekends, I have flown my 10 to Mexico. Baja for a Samaritan?s trip, and mainland for a Copper Canyon railroad trip (fantastic). We found Avgas readily available and if we averaged the cost in dollars per US gallon, it would come out to less than $4.00 USD (paying cash in pesos.). Buying with a US Credit card would be slightly higher but still less on average than stateside.
 
Dear Andrew, fair winds to you, sir!

With limited success, I?ve been trying to pierce together some info to understand the techical aspects of this engine. Is there somewhere I can read on it? I am not an engineer.

From what I gather, it is a two cycle engine where on the expansion stroke the firing piston charges/pressurises the next cylinder and so forth. Am I correct?

I wouldn?t think a discussion of the basic mechanics would infringe on Andrew?s proprietary know-how.

Thanks!
 
Dear Andrew, fair winds to you, sir!

With limited success, I’ve been trying to pierce together some info to understand the techical aspects of this engine. Is there somewhere I can read on it? I am not an engineer.

From what I gather, it is a two cycle engine where on the expansion stroke the firing piston charges/pressurises the next cylinder and so forth. Am I correct?

I wouldn’t think a discussion of the basic mechanics would infringe on Andrew’s proprietary know-how.

Thanks!

This site has the best explanation of the basic concept. They have been around for many years. http://www.bernardhooperengineering.co.uk/opads.htm

I could not find any US patents under Andy, but found several for the Hoopers. Peter Hooper is a PhD and did much on this engines analysis.

It is a relatively low compression, I am assuming due to the piston porting. I am not sure how it gets lubrication for the upper piston rings or what the pumping ratio is from the stepped to the primary combustion chamber. Reed valves prevent back flow. It would make a quite wide engine opposed configuration compared to a standard 4 cycle due to the long piston but the V config can package nicely. Should be very smooth, although at a little disadvantage for efficiency. Its main advantage is smooth, light, and fuel tolerant.

It needs about 10,000 hours of field operation work to prove out.

edit: Andy confirms he does have some patents in a later post. Maybe not publicly available in the USA patent search yet.
 
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From the Hooper UAV paper linked above:

....in a four-cycle engine all of the oil passes at some time into the high temperature region adjacent to the piston compression rings and is then returned to the crankcase...In stepped piston engines, however, this hot zone is lubricated by a simply metered small quantity of oil, on a total-loss basis.

Andrew, you there buddy? Upper rings are total loss lubrication? If so, how is it metered and supplied?
 
I would suspect this is done the same as in the high pressure compression world, which is my day job. We use small high pressure pumps that inject metered quantities (typically on the order of drops per minute, low single digit pints per day, running continuously) into the ring-wiped area via small bleeder holes in the cylinder wall, or occasionally through the piston itself on a few types.
 
The Hooper paper mentions 1:200 ratio for oil metering. Looks like a quart of oil per 50 gallons of fuel.
 
After reading about the Hooper engine design and seeing the test results I find nothing stunningly advantageous over modern 4 stroke engines. Power to weight ratios are similar at similar rpms and specific output is also similar, perhaps 10% better for the Hooper in both cases.

The oil stays clean but you have to add more and change less. Parts count is less and that should mean it may be less expensive to manufacture in the same quantities.

The big disadvantage is that the BSFC figures are not very good, especially when operating on heavy fuels. Might be ok for a UAV, not so good for civilian users paying their own fuel bills.

It's an interesting concept. Will be interesting to see the test figures on Andrew's E-330 engine.
 
After reading about the Hooper engine design and seeing the test results I find nothing stunningly advantageous over modern 4 stroke engines. Power to weight ratios are similar at similar rpms and specific output is also similar, perhaps 10% better for the Hooper in both cases.

You need to compare power to weight to comparable hp diesel engines, not gas engines. A diesel with even slightly better power to weight is a really good thing, especially as cheaper auto diesel will work just dandy without ethanol worries. Add to that, most diesels can be operated at or nearer to 100% power continuously compared to max recommended 75% power for gas, and that virtually all diesels are turbo-normalized. Each of those add something that most gas engines lack, except perhaps normalization for some gas engines.

In summary, cruising at 16,500' using 90% of rated power for a fuel flow lower than a gas engine will provide a substantial increase in cruise performance and range and cost savings vs a Lycosaurus.
 
Update with additional details

The most common question is asking about the production and testing status. Andy has completed fabrication of all production spec parts and started assembly of the first batch of engines last week. They began doing non-powered testing and found a common leak in a cylinder wall near a cooling port. After they dove into the issue, it was determined a manufacturing chamfer was causing the leak so an adjustment had to be made to the cylinder castings. Those were recast this week and should be back for assembly and testing by the end of the month. That was the only issue (other minor ones had already been solved) during final assembly, so it’s going smooth. Andy was a bit surprised and quite happy that he wasn’t seeing any other defects at this point like he expected. He is still on schedule for testing and initial delivery to an OEM in February and I’m aiming for my engine in April – May as scheduled.

Testing will begin in earnest once the assembly is complete and he’s got a lot of time scheduled for dyno and bench work. He has designed and manufactured all components in accordance with ASTM standards and will be conducting testing IAW their criteria as well. This is similar to what Rotax uses and I’ll be posting the criteria on my build log once I get that page built. He will be conducting additional proprietary and endurance testing as well.

The engine mount design has been finalized and analyzed for the RV-10. It uses a truss mount system with reinforcing tubing to attach the upper mounts while the truss supports the forward portion of the engine via the bed mount adapters. The trusses are currently being reviewed for ease of manufacturing as well as ability to locate accessories on the truss, eliminating the need for firewall mounting for most of the associated pumps and electrical components. The mount retains all stock bolt locations on the firewall and the nose gear strut attach points. Overall, his analysis sees a stiffness increase of 30% over the stock Van’s mount, although I cannot attest to actual details of that statement since I’m not a mechanical engineer.

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Andy’s goal is to offer a complete power unit to customers. This would mean the engine, engine mount, dual ECUs, ignition, sensors and harness, oil pump and filter, coolant pump, alternator (see below), and exhaust (turbo if desired at extra cost) would all be included in the purchase price. The builder would need to provide fuel pumps (see note below), coolant radiator, oil cooler, and any required cowling modifications (details coming soon on that). This is pretty different than the Lycoming packages out there now, as builders often have to piece meal the power unit together with exactly what they want. His goal is a seamless installation and complete package all designed to work together to be reliable, efficient, and powerful. I’m hoping all that is true since I’ll be the first to test it out! I’m also working hard with some help from others to sort the details out and make it successful.

At this time, we are projecting using an engine master switch in the cockpit to power an engine bus consisting of all pumps, ECUs, and ignition. While some may desire a switch for each ECU and ignition, a failure of either would be indicated in the cockpit via CAN bus and a fault light (similar to your car’s check engine light). Either ECU can run the entire engine. I’m still asking about ignition coils. With the engine master, it will be possible to apply master switch power to the aircraft and not have ECUs, pumps, etc. run unnecessarily. It also allows for the master switch to be turned off in flight in the event of electrical component failure and still have power to the engine (assuming the fault isn’t in the engine bus wiring!), helping to minimize the impact of electrical faults.

The alternators will be available in 40, 60, 100, and 120 amp versions. The generators that are modeled on the attached picture (on the front side of the accessory gear box just under the case, the bottom most cylinder is the starter motor) are an extremely lightweight 40 amp model that will not be included in the base package price. He left those on the drawing to illustrate the option, as some markets may want the light weight and not need high amperage output. The traditional looking alternators are spline driven and mount to the rear of the accessory gear box. One alternator of the customer’s choice of rating will be included and a second alternator will be an option. I have asked about possibly using a third on the front mounts with the B&C vacuum pad mount being the model of choice. I ask about the third because I will be using one alternator on a 24 volt system to power my AC, including the compressor, eliminating a belt driven engine mount compressor.

Andy is working really hard and has every intention of keeping to the projected price of the engine. We talked for a while about the need to be competitive in the market and he understands that. He realizes that even if the engine is a game changer, no one is going to buy it for $100k compared to a Lycoming. He is aiming for accurate manufacturing, reduced parts counts, and efficiency of the design with shared parts of the V12 to keep costs under control. He is also looking to include an incredible warranty with the engine for builders. I can’t go into the details, but let’s just say that Andy will personally and professionally stand behind each engine. More details will be coming soon, and if it all works out, the warranty will be a game changer.

Projected maintenance is going to be vastly different than a traditional Lycoming. With the oil not coming into contact with the combustion side of the piston, the oil is not exposed to extreme temperatures and its only purpose is to splash the connecting rods/pins and lubricate the main journal bearings. Therefore, oil changes will be few and far between. He has performed over 400 hours on one engine without needing to change the oil. This is due to the additives lasting longer with reduced heat. It will also reduce the size of the oil cooler needed. TBO conversations are ongoing and will depend on testing results. Andy does want to minimize the need for builders/users to tear the engine down. Quite frankly, he stated he doesn’t want people “dicking around” with his engine, he wants them flying it.

Finally, Andy and AC-Aero will be exhibiting the new V4 Hawk at Oshkosh this year in the EAA Innovation tent! I’m sure he will get quite a bit of attention there and we all hope he has some great testing data to share with others. I aim to have mine installed and possibly test run by that time so I’ll be able to share some photos as well. I’m not sure if I’ll be at OSH or what dates I’d be up there as I just got a new role as Executive Officer for my C-17 wing here, so will be busy.

Anyway, lots of information. I hope it answers some questions and generates others. We’ll have another call in a few weeks then go quiet for a while so Andy can focus on testing and delivery. Feel free to drop me a message if you’d like. Thanks!
 
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I'll ask Andy about the lubrication for the upper rings. I'm not sure of the details on that myself, but it's a great question to ask.

Testing will give us more specific details about power / torque curves as well as fuel burn, so I can't quote any exact numbers on that. Based on testing, the engine is expected to produce more power at less fuel flow than a Lycoming, however, that hasn't been proven with test numbers yet.
 
You need to compare power to weight to comparable hp diesel engines, not gas engines. A diesel with even slightly better power to weight is a really good thing, especially as cheaper auto diesel will work just dandy without ethanol worries. Add to that, most diesels can be operated at or nearer to 100% power continuously compared to max recommended 75% power for gas, and that virtually all diesels are turbo-normalized. Each of those add something that most gas engines lack, except perhaps normalization for some gas engines.

In summary, cruising at 16,500' using 90% of rated power for a fuel flow lower than a gas engine will provide a substantial increase in cruise performance and range and cost savings vs a Lycosaurus.

Neither the Hooper or E-330 are diesels, they are heavy fuel capable, SI designs. I am confused...

The Hooper engine has dreadful BSFC- especially on Jet A.
 
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Yes

Yes, people keep confusing this Combined Cycle engine with a Diesel compression ignition engine...it is not.
 
Neither the Hooper or E-330 are diesels, they are heavy fuel capable. I am confused...

The Hooper engine has dreadful BSFC.

The bsfc is characteristic of the type. It is left to the imagination as to just exactly how this heavy fuel engine works. It is supposed to be "spark ignited" but no discussion on whether it is fumigated or some form of direct injection. The Hooper site and some papers do refer to the heavy fueled engines being advantaged by a common rail fuel system. I would agree with that, as the combustion could be spark initiated then the injected fuel used to control heat release, i.e. no chance for detonation. Even a diesel cycle compression ignited engine can have a form of detonation, usually mentioned as excessive rate of (pressure) rise. Turbocharging will can certainly make up some of the expansion ratio challenge (low) by work recovery in the turbine.

In the engine world, this holy grail of a multi fuel capable engine has been around for a long time, particularly for military applications. The only way it is really viable (so far), is when you look at the cost of the whole gasoline infrastructure for the Navy for example. It yields a cost of over $400/gal at point of use. If the recip was as reliable as a turbine (PT6), then it's (hopefully) lower cost would provide some advantages.

We should discuss off line some times.
 
Tim, you are putting experiment back into experimental aviation and test flight back into phase I and phase II. More power to you.
 
Tim,

Thanks for the detailed update. A really good warranty and complete installation package will help people make a switch from traditional engines if the performance and durability/ reliability is there I think.
 
Check out the Facebook RV-10 page for some pictures while I try to figure out my malfunctioning build log website.
 
Neither the Hooper or E-330 are diesels, they are heavy fuel capable, SI designs. I am confused...

The Hooper engine has dreadful BSFC- especially on Jet A.

Ah, I was focused on the Higgs Diesel thread title and so misread your post.
 
No worries, the diesel moniker was confusing to me as well initially. HFSI (Heavy Fuel Spark Ignition) might be a be a way to avoid confusion.
 
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Finally got the pictures loaded. More to come but I?m tired of inter web dealings for tonight!
 
I'll pass the feedback on about his name.

Just to clear it up, the engine is not a traditional diesel engine. It is a heavy fuel, spark ignighted engine.

Moving on, I'll post an update on the fuel system as we've worked out the details on the architecture. I finally got my build log website back up to host the pictures.
 
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