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DeltaHawk for RV-14

czechsix

czechsix

Well Known Member
Just saw this in the EAA newsletter:

DeltaHawk Engines Developing RV-14 Package

DeltaHawk Engines announced this week that engineering and development is now underway on a firewall-forward installation package for the company’s new DHK family of FAA-certified jet-fuel-powered piston engines for Van’s RV-14 aircraft. The first installation will be aboard an RV-14 owned by Lindy-winning aircraft builder Craig Saxton, EAA 432253, and the aircraft is anticipated to fly during late spring 2024.

I would sure be interested in this if it comes to fruition, assuming it is a well developed firewall forward package and is cost competitive with the IO-390. One obvious downside is it will require a new engine mount and presumably a new cowl as well, and Van's won't let you delete these items from the finish kit anymore. Maybe if there's enough interest Van's will eventually get behind this effort (sort of like they've done with Beringer wheels & brakes) if/when they have time to think about product development again...
 
czechsix said:
Just saw this in the EAA newsletter:

DeltaHawk Engines Developing RV-14 Package

DeltaHawk Engines announced this week that engineering and development is now underway on a firewall-forward installation package for the company’s new DHK family of FAA-certified jet-fuel-powered piston engines for Van’s RV-14 aircraft. The first installation will be aboard an RV-14 owned by Lindy-winning aircraft builder Craig Saxton, EAA 432253, and the aircraft is anticipated to fly during late spring 2024.

I would sure be interested in this if it comes to fruition, assuming it is a well developed firewall forward package and is cost competitive with the IO-390. One obvious downside is it will require a new engine mount and presumably a new cowl as well, and Van's won't let you delete these items from the finish kit anymore. Maybe if there's enough interest Van's will eventually get behind this effort (sort of like they've done with Beringer wheels & brakes) if/when they have time to think about product development again...
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I checked out that engine in KOSH last summer as it seemed promising.
Consider that it's heavier than a Lyco, runs on 24V, 180 HP, and... estimated selling price was north of 100k USD...
Correct me if I'm wrong.
 
On the one hand, DeltaHawk is pretty close to vaporware. They’ve been saying for literally 20+ years that, very soon, you’ll be able to buy this cool engine from them, any day now!

On the other hand: The moment they said they certified the engine (which is a decently reliable sign that the design is finalized and relatively polished and reliable), I though: “That would be a great engine for an RV-14!” (or 15, for that matter). Weight comparable to an IO-390, less hp but all the advantages of diesel/jet-A. I was like “I hope someone figures out how to put it on a 14!”.

On the other other hand… Holy crap, $110K?!?! I had been wondering whether diesel engines had been going up in price along with Lycomings, now I know. (And now, to do the math on how many flight hours it would take for it to pay for itself in fuel savings…)

In any case: Another option for the inevitable post-100LL era.
 
I met with Deltahawk in 1999. I got a T shirt and a promiss.

But, I consider the design as the only viable Jet A option.

Considering I've been waiting for my Thunderbolt IO-540 for close to three years (and no end in sight) if they produce a 220HP or so variant at a comparable price to the Thunderbolt IO-540 then I'd jump in line.

Carl
 
How about DeltaHawk buys Vans. Then design airplanes around these engines...I'm in! At some point we need to move on with more modern engines that burn a readily available, non-novelty, fuel.
 
MV-RVer said:
Kitplane just posted this article.

www.kitplanes.com

DeltaHawk To Build FWF Package for Vanâs RV-14 - KITPLANES

The first installation will be on Craig Saxton’s already flying RV-14 and is “anticipated to fly during late spring 2024.”
www.kitplanes.com www.kitplanes.com
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$110k for fwf with prop might not be too bad after we see the revised engine/prop pricing from Vans, especially with the ability to use Jet-A and lower maintenance. I can't remember what the IO-390 with MT prop pricing was, but for some reason ~$70k is in my head.

Could be an interesting choice- hopefully they can pull it off.
 
When Glasair put the Austro diesel on the Sportsman lots of folks, including myself, wondered about the cost. It turns out the cost delta between spark ignition IO390 and prop vs diesel and prop was $80K. That seemed like a lot of money. Some folks say "no way would I spend that much for an engine that makes less power than the gasoline engine". If one was only looking at the "down low" performance numbers the diesel Sportsman would not impress. As soon as one starts to climb the diesel Sportsman leaves the Lycoming in the dust, or rather, in its soot trail.

The ability to flat-rate power at altitude, plus the ability to operate in regions where avgas is nearly unobtainable changes the value evaluation from purely a cost analysis to a cost-benefit analysis.
 
cjs said:
I think many will be surprised with the DH engine that will be in the RV14 and how well it pairs with the plane.

Meanwhile - a good article with lots of relevant information is this article from the Cessna Pilots Magazine - it covers a lot of ground.

https://www.deltahawk.com/wp-content/uploads/2023/12/CessnaPilotsMagazine-DeltaHawk-Nov2023.pdf
Click to expand...

I probably should have mentioned that I am the person who owns and is building the RV14 with the DeltaHawk engine (its not going in my current RV14 as was stated in the Kitplanes article). That said, I would recommend reading the article linked above. It covers a lot of ground and addresses many of the thoughts, concerns, issues mentioned in some of the posts above. We hope to be flying by late Spring as well as to have the plane at Oshkosh 2024. Still a bit early in the process to know if we'll hit those objectives - but, its certainly possible from where we stand currently.
 
cjs said:
I am the person who owns and is building the RV14 with the DeltaHawk engine
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Thank you very much for blazing this trail!

Please keep us posted (to the extent that whoever else is investing into this project - e.g. the DeltaHawk folks - feel comfortable sharing info about the development, prototyping, tests, etc).
 
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If VANS want to maximise their market outside the US they would do well to get right behind this initiative. For instance in UK currently we pay for AVGAS the equivalent of $9.56 a US gallon whereas for JETA we pay $5.05. Now, for example, if you do 100hrs per year at 7.5 galls per hour on JETA and 9.5 gall/hr on AVGAS your fuel cost is between $9100 and $3800 so saving $5300 a year. That’s mount up over 20 yrs useful life to the cost of the engine. Then there are the maintenance savings at upto $6000 a year, after 20 years you could pay for your kit, electronics and engine from the savings. All to be proven but very compelling

if these things are reliable and they have a 6 cylinder version it will, over time, destroy Lycoming business outside USA. It might even foment some innovation at Lycoming
 
Mike Houston said:
If VANS want to maximise their market outside the US they would do well to get right behind this initiative. For instance in UK currently we pay for AVGAS the equivalent of $9.56 a US gallon whereas for JETA we pay $5.05. Now, for example, if you do 100hrs per year at 7.5 galls per hour on JETA and 9.5 gall/hr on AVGAS your fuel cost is between $9100 and $3800 so saving $5300 a year. That’s mount up over 20 yrs useful life to the cost of the engine. Then there are the maintenance savings at upto $6000 a year, after 20 years you could pay for your kit, electronics and engine from the savings. All to be proven but very compelling

if these things are reliable and they have a 6 cylinder version it will, over time, destroy Lycoming business outside USA. It might even foment some innovation at Lycoming
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Mike, I would suggest that 9.5 gal/h is generous. I also fly a C172 RG with a 180HP O-360. High speed cruise is 9 GPH without agressive leaning. So it could/can be less.
On my RV-8, with the 200 HP IO-375, and 50°F LOP, I easily get 7.5 GPH.
At that rate, 750 gallons/year for both engines, I propose a $3400 saving burning JetA.
And where does $6000/year maintenance savings come from? $60/hour ??

As per our differing numbers, in Europe, in a year flying 100 hours, saving $3400 - $5300 in fuel will amount to $68000 - $106000in 20 years.
Say $45000 for a IO-360, v.s. $100000 for a DeltaHawk, that's $55000 more, so $13000 - $51000 savings in 20 years or $650 - $2550 per year.
Let's average, $87000 savings against $55000 more expense at purchase is $32000 global saving. $1600/year, flying 100 hours a year, every year for 20 years.
Not peanuts but nowhere near paying for the kit, electronics and engine...

Most privately operated airplanes are flown less than 100 hours/year, so money benefits are questionnable.
Commercial ops that fly 500 - 800 hours/year per aircraft will certainly benefit financially.
Savings are of course in order just with the important price difference between 100LL and JetA in Europe.

We can argue all day as numbers can be manipulated to "sell" stuff or convince people. I just offer another more moderate view.
Future availability of 100LL is a concern, more so in remote airports already here in Northern Canada.
A JetA recip aircraft engine does have certain advantages in certain circumstances, but they are not currently "win-win" for everyone.
Medium to long term, I think JetA might clearly overtake 100LL use in GA, but I don't think I will live to see that.
 
riseric said:
Mike, I would suggest that 9.5 gal/h is generous. I also fly a C172 RG with a 180HP O-360. High speed cruise is 9 GPH without agressive leaning. So it could/can be less.
On my RV-8, with the 200 HP IO-375, and 50°F LOP, I easily get 7.5 GPH.
At that rate, 750 gallons/year for both engines, I propose a $3400 saving burning JetA.
And where does $6000/year maintenance savings come from? $60/hour ??

As per our differing numbers, in Europe, in a year flying 100 hours, saving $3400 - $5300 in fuel will amount to $68000 - $106000in 20 years.
Say $45000 for a IO-360, v.s. $100000 for a DeltaHawk, that's $55000 more, so $13000 - $51000 savings in 20 years or $650 - $2550 per year.
Let's average, $87000 savings against $55000 more expense at purchase is $32000 global saving. $1600/year, flying 100 hours a year, every year for 20 years.
Not peanuts but nowhere near paying for the kit, electronics and engine...

Most privately operated airplanes are flown less than 100 hours/year, so money benefits are questionnable.
Commercial ops that fly 500 - 800 hours/year per aircraft will certainly benefit financially.
Savings are of course in order just with the important price difference between 100LL and JetA in Europe.

We can argue all day as numbers can be manipulated to "sell" stuff or convince people. I just offer another more moderate view.
Future availability of 100LL is a concern, more so in remote airports already here in Northern Canada.
A JetA recip aircraft engine does have certain advantages in certain circumstances, but they are not currently "win-win" for everyone.
Medium to long term, I think JetA might clearly overtake 100LL use in GA, but I don't think I will live to see that.
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Well I accept your point, I think the $100k is for the whole firewall forward including a prop. Not sure what a like for like comparison would be. The maintenance was taken from the Cessna article above but on reflection that’s probably a certified aircraft maintenance costs. The article mentions a similar cost for the Lycoming certified engine but once again that’s a different kettle of fish. In hindsight I probably over iced the cake.
 
IO390 is 297lbs and Deltahawk is 363lbs.
What happened to build it light?
 
I have followed this Delta Hawk story for a very long time and I have arrived at a point where I believe very little of what I hear and even less of what I see.
I wish that company nothing but the best and I hope I will see the day when one of these "modern" Jet A burning examples will take to the skies.
The numbers so far are all conjecture and in a number of cases pure exaggerations as has been mentioned by others.
Another angle you might consider is the price which I don't believe will be $100,000 and certainly not include the prop, that is simply wishful thinking.
Lets say you pay $50,000 for a Lyc and buy yourself a 20 year treasury bond. (a very conservative investment) with the $50,000 left over.
Even at lower rates than today you will have more than doubled your money after 20 years. Just something to think about.
Pushing the idea of Carbon neutrality on their webpage is yet another dubious pitch to sell make believe advantages to their product.
 
"For Experimental aircraft, we are currently working on packages for RV-10, RV-14, and Bearhawk 4-place. We will publish progress on our website and social media. Packages for other aircraft to follow."

They got my attention.
 
cactusman said:
"For Experimental aircraft, we are currently working on packages for RV-10, RV-14, and Bearhawk 4-place. We will publish progress on our website and social media. Packages for other aircraft to follow."

They got my attention.
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They had my attention decades ago. Here I sit with a lycosaurus.
 
riseric said:
We can argue all day as numbers can be manipulated to "sell" stuff or convince people.
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Paraphrasing Benjamin Disraeli & Mark Twain: There are Lies, Damned Lies, Statistics, Business Cases, and Safety Risk Analyses!

(The last two items I added based on my experience in the Aerospace industry.)
 
cjs said:
I probably should have mentioned that I am the person who owns and is building the RV14 with the DeltaHawk engine (its not going in my current RV14 as was stated in the Kitplanes article). That said, I would recommend reading the article linked above. It covers a lot of ground and addresses many of the thoughts, concerns, issues mentioned in some of the posts above. We hope to be flying by late Spring as well as to have the plane at Oshkosh 2024. Still a bit early in the process to know if we'll hit those objectives - but, its certainly possible from where we stand currently.
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Thank you for stepping up to the plate for this project. I've been curious about how far DH had actually come and this should bring much to light.
 
cjs said:
I probably should have mentioned that I am the person who owns and is building the RV14 with the DeltaHawk engine (its not going in my current RV14 as was stated in the Kitplanes article). That said, I would recommend reading the article linked above. It covers a lot of ground and addresses many of the thoughts, concerns, issues mentioned in some of the posts above. We hope to be flying by late Spring as well as to have the plane at Oshkosh 2024. Still a bit early in the process to know if we'll hit those objectives - but, its certainly possible from where we stand currently.
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Craig,

Thanks for taking this project on. I am wishing you success big time! I am on my RV-14 wing kit now, getting ready to finish my tanks this month. Will probably hold off installing the rear baffles just in case I need to move the vent line to make room for a larger Jet-A frange/cap. Two questions (for now, I’m sure I will have more)…..Do you think the first DeltaHawk RV-14 engine mount kit be for the 14 or the 14A? Should I keep the return fuel line on the tank where it is currently depicted on the plans?

Respectfully,

Mike Yankovich
 
riseric said:
And where does $6000/year maintenance savings come from? $60/hour ??
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Yeah I'm a little curious about that number too :unsure:

For sure, I can see the savings in fuel costs if you're not in the US. But a quick scan of reported Jet-A vs 100LL prices here in Georgia shows less than $1/gallon difference at any given airport, and the Jet isn't necessarily cheaper (if they have it at all; some small airports don't). If you can run mogas, even that savings probably goes away.

I like the idea of Jet-A, FADEC, and all that, but the capital cost is just way too much.
 
rmartingt said:
Yeah I'm a little curious about that number too :unsure:

For sure, I can see the savings in fuel costs if you're not in the US. But a quick scan of reported Jet-A vs 100LL prices here in Georgia shows less than $1/gallon difference at any given airport, and the Jet isn't necessarily cheaper (if they have it at all; some small airports don't). If you can run mogas, even that savings probably goes away.

I like the idea of Jet-A, FADEC, and all that, but the capital cost is just way too much.
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I don’t know how much cost difference it will be if Lycoming keeps increasing their prices. I hate the fact that we are forced to buy a $90K engine designed to run on a fuel that the government wants to phase out (being replaced by something more expensive). I don’t see any desire by Lycoming to adapt their 390 to run on mogas. Jet-A is not one lawsuit away from going away (yet). I just don’t have much faith in the FAA or GA to solve the 100LL replacement issue (just denial that it’s a problem)
 
Now if DeltaHawk comes through with their long promised 220hp version of this engine, I’d jump at putting this into my RV-10 project (the project that has been stalled for a couple of years waiting on the front seats and the Thunderbolt engine).

Carl
 
Yank said:
I don’t see any desire by Lycoming to adapt their 390 to run on mogas.
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I could be wrong but I think I’ve heard of a lower-compression version (mod?) of the 390 that can burn mogas, sacrificing some hp. I think I’ve heard that in the context of the Glasair Sportsman. I’ll do some Googling and see if I can come up with anything.

Carl Froehlich said:
Now if DeltaHawk comes through with their long promised 220hp version of this engine, I’d jump at putting this into my RV-10 project
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Why not an SMA305-230? Flyer (the quickbuilt assemblers in Brazil) have ironed out the kinks and certified that installation. My understanding is that they plan to start offering a FWF package any day now.
 
Carl Froehlich said:
Now if DeltaHawk comes through with their long promised 220hp version of this engine, I’d jump at putting this into my RV-10 project (the project that has been stalled for a couple of years waiting on the front seats and the Thunderbolt engine).

Carl
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I just put in my $1,000 reservation fee...
 
Yank said:
Craig,

Thanks for taking this project on. I am wishing you success big time! I am on my RV-14 wing kit now, getting ready to finish my tanks this month. Will probably hold off installing the rear baffles just in case I need to move the vent line to make room for a larger Jet-A frange/cap. Two questions (for now, I’m sure I will have more)…..Do you think the first DeltaHawk RV-14 engine mount kit be for the 14 or the 14A? Should I keep the return fuel line on the tank where it is currently depicted on the plans?

Respectfully,

Mike Yankovich
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Mike,

The first DH engine install is for the RV14 (the tail dragger). Also, if you haven't seen DeltaHawk's most recent press release - there will be 200 HP and 235 HP versions of the DHK engine (DHK200 and DHK235). We are using the DHK200 in the current build we're doing at Synergy Air (Eugene, OR). As for specifics on the build questions you posed - I really can't comment with specificity until we have the plane finished and flying. That said, its reasonable to assume a different fuel filler/cap assembly, as well as a different fuel valve and return line set-up (we are actually working on these as I write this). We hope that if all goes well, Vans will offer a FF package for the DeltaHawk that has all the goodies that differ from the Lycoming installation. A few random notes that may be of interest to you and others that I can share:

*We will be using 12V electrical system.

*Engine Start procedure is a bit different from the normal Lycoming SOP, but not too different (eg Glow Plug/Start Switch vs Key Start, No Mags to check, etc). Aerotronics (Billings, MT), who has done scores of panels with us at Synergy Air, is helping with the panel design/fabrication and to ensure all the Garmin stuff plays well (Jason over there is top notch and very knowledgable). The panel is very similar to what has worked very well in my current RV14. The new DH RV14 will have a full IFR panel (2 x G3X's, GTN750, A/P, as well as a back-up nav system that runs off the Sentry and Foreflight). I will post the panel when we get a bit further into the project.

*We are expecting some very impressive cruise numbers - especially as one gets into the teens. Cruise should bump up against the Vne - but, again, until we flight test its too early to say for sure. Clearly, it will be fast. As a point of comparison, at 12,500 msl my current RV14 sees between 174 KTAS (LOP/2400 rpm/9.5 gph) and 179 KTAS (ROP/2600 rpm/11.5 gph). On the high side of these numbers, the engine is making 64% power (about 140 hp, *my IO-390 dyno'd at just over 220 hp). With the DH, the engine will still be making approx full power (200 hp) into the teens, so its easy to see why the cruise speed should be significantly higher. And, with the DH's better fuel efficiency, its not improbable that one could achieve these numbers using the same amount of fuel the lycoming consumes generating less speed.

A few additional notes on the numbers. My current Lycoming install is a bit unusual. The IO-390 is the Thunderbolt edition with a .5 compression bump. So, it puts out just over 220hp. Secondly, we also fabricated a 'Sam James-esque' cowl that increased our top speed from 184 KTAS to 191 KTAS (we had the stock cowl for about 70 hours before we made this change). So, the overall point is that comparing the DH to my current RV14 performance numbers is not quite like comparing it to a stock RV14's. That said, the DH should still compare very favorably.

Here is the link to the info on the additional engine variants: https://www.deltahawk.com/2024/02/01/deltahawk-introduces-higher-power-engine-options/

Attached also for reference see pics of cruise info on the my current RV14 showing the numbers mentioned above for 12,500 MSL cruise. LOP.jpgROP.jpg
 
The resolution on the panel pics above isn’t great - these should be better. Also, note that the G3x computed engine power (%) - shown by the rpm gauge, and the TAS is shown above the IAS ribbon.IMG_2574.jpegIMG_2575.jpeg
 
That said, its reasonable to assume a different fuel filler/cap assembly, as well as a different fuel valve and return line set-up (we are actually working on these as I write this).
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I may hold off on my tanks for a bit in case they come up with a different fuel filler/cap just incase this engine becomes an option for me closer to completion.
 
Is the DeltaHawk approved for aerobatics
If not is that something that will be looked at for the future
For me that would be a dealbreaker if it’s not capable of aerobatics
 
cjs said:
*We are expecting some very impressive cruise numbers - especially as one gets into the teens. Cruise should bump up against the Vne - but, again, until we flight test its too early to say for sure. Clearly, it will be fast. As a point of comparison, at 12,500 msl my current RV14 sees between 174 KTAS (LOP/2400 rpm/9.5 gph) and 179 KTAS (ROP/2600 rpm/11.5 gph). On the high side of these numbers, the engine is making 64% power (about 140 hp, *my IO-390 dyno'd at just over 220 hp). With the DH, the engine will still be making approx full power (200 hp) into the teens, so its easy to see why the cruise speed should be significantly higher. And, with the DH's better fuel efficiency, its not improbable that one could achieve these numbers using the same amount of fuel the lycoming consumes generating less speed.

A few additional notes on the numbers. My current Lycoming install is a bit unusual. The IO-390 is the Thunderbolt edition with a .5 compression bump. So, it puts out just over 220hp. Secondly, we also fabricated a 'Sam James-esque' cowl that increased our top speed from 184 KTAS to 191 KTAS (we had the stock cowl for about 70 hours before we made this change). So, the overall point is that comparing the DH to my current RV14 performance numbers is not quite like comparing it to a stock RV14's. That said, the DH should still compare very favorably.

Attached also for reference see pics of cruise info on the my current RV14 showing the numbers mentioned above for 12,500 MSL cruise.
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The key to getting really good performance out of the DeltaHawk installation (just like with any engine) will be the design of the cooling inlet(s), diffuser, radiator(s), and exit. I've seen a lot of liquid cooled automotive conversions over the years in homebuilt airplanes with very poor cooling designs, and correspondingly poor performance numbers. You could easily end up with an RV-14 that is slower and/or has worse mpg than the IO-390 installation despite the better efficiency of the DeltaHawk powerplant itself if you don't optimize the installation for low cooling drag, and that can take quite a bit of testing and iteration to get it really dialed in. It's interesting to look back at the WWII era and see lots of examples of radiator design (in the cowl, wing leading edges, scoops under the wing, and the iconic belly scoop of the P-51). The Mustang won the award for most efficient cooling design but it came at cost of significant weight and complexity, and a similar design in an RV-14 would intrude into the baggage area with considerable structural and W&B implications. So I assume you'll be putting one or two radiators in the cowling and then doing your best to package a decent inlet, diffuser, and a variable pilot controlled exit door/cowl flap into that non-optimal space. It may or may not be possible to use the existing RV-14 cooling exit door for the DH installation. Looking forward to seeing what you come up with!
 
I don’t know how much cost difference it will be if Lycoming keeps increasing their prices. I hate the fact that we are forced to buy a $90K engine designed to run on a fuel that the government wants to phase out (being replaced by something more expensive). I don’t see any desire by Lycoming to adapt their 390 to run on mogas. Jet-A is not one lawsuit away from going away (yet). I just don’t have much faith in the FAA or GA to solve the 100LL replacement issue (just denial that it’s a problem
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The 390 is a high compression engine specifically designed for high octane fuel. You can adapt the mogas solution yourself without the blessings of Lycoming by lowering the compression ratio and burning mogas E10 avaialble everywhere. (hundreds of us are doing it) If you are concerned about Jet-A going away in the future, you'd do well by exercising your experimental privileges and adapt a mogas burning installation. With this simple set up and all things considered, including purchase price, fuel consumption and cost of fuel, you'll be miles and dollars ahead of any new DH or I0-390.
 
N427EF said:
The 390 is a high compression engine specifically designed for high octane fuel. You can adapt the mogas solution yourself without the blessings of Lycoming by lowering the compression ratio and burning mogas E10 avaialble everywhere. (hundreds of us are doing it) If you are concerned about Jet-A going away in the future, you'd do well by exercising your experimental privileges and adapt a mogas burning installation. With this simple set up and all things considered, including purchase price, fuel consumption and cost of fuel, you'll be miles and dollars ahead of any new DH or I0-390.
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All valid points. Based on what I have been told, If you go with the reduced compression IO-390/adjust the spark, it will allow you to run MOGAS and avoid predetonation. Another option is to stay with a normal compression IO-390 and do reduced thrust ops. I’m told vapor lock will still be an issue with a normal engine driven fuel pump at high altitudes (above 8K). I believe EFII systems can solve all MOGAS issues but it will drive up complexity and cost. I believe Jet-A will remain an aviation fuel for the foreseeable future but I believe 100LL is in the crosshairs. I hope I’m wrong but I think 100LL is only going to get more expensive and less available over time. If you want to go the MOGAS rout, availability at FBO’s may become difficult. The reduced compression/thrust option is a compromise with restrictions, the EFII option is impressive but adds some complexity to the electrical systems. The DeltaHawk option has some advantage. Jet-A will be easier to find and use than MOGAS, it may actually reduce complexity of the engine systems (fuel and electrical) and increase performance. However…….. the cost delta and complexity of the FWF package is yet to be determined.
 
I would be concerned about the prop that would be available with the new engine. I would want to insure that there were no harmonics that could lead to failures.
 
USN bullet said:
I would be concerned about the prop that would be available with the new engine. I would want to insure that there were no harmonics that could lead to failures.
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Things to consider:
- This engine is certified for spam cans. Propeller application is part of that certification.
- I understand the engine can use any prop the Lycoming can use. The engine uses a standard prop governor.
- This is a two stroke direct drive engine. So for the same RPM as a Lycoming there are twice as many power strokes. I consider this mandatory for any diesel engine option.

Carl
 
Carl Froehlich said:
Things to consider:
- This engine is certified for spam cans. Propeller application is part of that certification.
- I understand the engine can use any prop the Lycoming can use. The engine uses a standard prop governor.
- This is a two stroke direct drive engine. So for the same RPM as a Lycoming there are twice as many power strokes. I consider this mandatory for any diesel engine option.

Carl
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Be careful here.

Engine certification (Part 33) and propeller certification (Part 35) are separate and stand alone. It is not until they are combined at the airframe level that they are required to be compatible (previously 23.907, now 23.2400) with each other. Once the engine is TC'd or STC'd onto an airplane with a specific propeller, then that specific propeller/engine combination must have been shown to be compatible (with any resultant operating restrictions).

While it may use the same propeller engine flange interface that a Lycoming does (which one, there are a couple), and thereby might attach to any propeller that a Lycoming uses, it is absolutely not true that the DeltaHawk is compatible with any propeller that works on a Lycoming. Even propellers compatible with specific Lycomings are not compatible with other, specific Lycomings.
 
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TParker said:
Be careful here.

Engine certification (Part 33) and propeller certification (Part 35) are separate and stand alone. It is not until they are combined at the airframe level that they are required to be compatible (previously 23.907, now 23.2400) with each other. Once the engine is TC'd or STC'd onto an airplane with a specific propeller, then that specific propeller/engine combination must have been shown to be compatible (with any resultant operating restrictions).

While it may use the same propeller engine flange interface that a Lycoming does (which one, there are a couple), and thereby might attach to any propeller that a Lycoming uses, it is absolutely not true that the DeltaHawk is compatible with any propeller that works on a Lycoming. Even propellers compatible with specific Lycomings are not compatible with other, specific Lycomings.
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I noticed that the SR20 testbed that DeltaHawk has been using for a number of years now has flown at least two different models of Hartzell 3-blade propellers. Not sure if Hartzell did any testing or analysis on these combinations or if DeltaHawk just went ahead and installed them for flight test purposes without Hartzell's blessing...since it's on Experimental R&D no certification approval is needed yet. Pretty sure both of these props have carbon fiber composite blades, and I'd be surprised if any aluminum prop ever gets certified for use with a diesel engine. Hartzell makes a great product but their composite 3-blade props have eye watering price tags, so that in combination with the price point on the DeltaHawk is going to make it a pretty expensive firewall-forward solution for the RV series.
 
czechsix said:
I noticed that the SR20 testbed that DeltaHawk has been using for a number of years now has flown at least two different models of Hartzell 3-blade propellers. Not sure if Hartzell did any testing or analysis on these combinations or if DeltaHawk just went ahead and installed them for flight test purposes without Hartzell's blessing...since it's on Experimental R&D no certification approval is needed yet. Pretty sure both of these props have carbon fiber composite blades, and I'd be surprised if any aluminum prop ever gets certified for use with a diesel engine. Hartzell makes a great product but their composite 3-blade props have eye watering price tags, so that in combination with the price point on the DeltaHawk is going to make it a pretty expensive firewall-forward solution for the RV series.
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I have no idea what goes into certifying a prop engine combination but it would seem that a two stroke diesel would put less stress on a prop because the power pulses for the same RPM are more evenly spaced. I could be wrong…..
 
Yank said:
I have no idea what goes into certifying a prop engine combination but it would seem that a two stroke diesel would put less stress on a prop because the power pulses for the same RPM are more evenly spaced. I could be wrong…..
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The power pulses of the DeltaHawk will be twice the frequency of a 4-stroke, 4-cyl engine at a given rpm. While this might be perceived as smoother to the pilot, the higher compression results in a harder, more 'jarring' power stroke and that puts more stress on all of the rotating machinery including connecting rods, crank, bearings, and prop. It might be possible to use an aluminum prop with the DeltaHawk but the heavier blades (compared to carbon fiber) put more stress on the hub and aluminum blades are more likely to have harmonic frequencies (think tuning fork) that result in operating limitations in certain RPM ranges, and maybe a lower TBO as well. IMO a carbon fiber prop is the more likely solution for DeltaHawk and it has the additional benefit of significantly lower weight vs. aluminum...which will be important to offset the higher FWF weight of a liquid cooled diesel engine.
 
Reading the progress with DeltaHawk I believe they are doing engine/prop combo testing, using instrumented props, to verify compatibility.

Carl
 
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