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New engine.

Roarks

Active Member
New Radial engine.

So...
I started in over at the propeller thread and got a lot of great information, lets see how the engine thread goes...

I've been working on a ground up engine design. I think I started the first assembly model back in 2013 and have been refining things since. The amount of effort and education I've put into this thing is ridiculous. I want to say it's a significant factor to me getting my A&P cert, spent thousands on books, and an engineering friend that works at GM probably thinks oh **** here goes another hour when I call.

I've gotten distracted a few times. I've played with low altitude turbine design, I've played with 2 stroke and 4 stroke diesel with fancy fuel injection, tried spark ignition jet A... which there might still be something there but my "carb" fouls itself in a matter of hours... The more I mess with the exotic stuff the more I realize by the time I'm done with my RV8 kit... Electric will probably be a serious option. :rolleyes: I'm a mechanical engineer not an EE PHD and battery materials research scientist. I build metal things.

So why not do something simple, tried and true, and cool... A RADIAL! Plain old aviation style, air cooled, 100LL radial. (Does anyone actually use their mogas STC? Where do you get non ethanol fuel that's cheaper than 100LL!?)

(is the guy that made the RV-8R around here, I would love to ask some questions regarding airframe mods, thrust line so on...)

My day job is an Aerospace engineer and I focus a lot on manufacturing. My first design point is manufacturabiliy with pretty much any CNC is a must. That removes specialized processes and makes low quantities a non-issue... just ask any company that used to do aircraft forgings, low cost maching has really changed the game... and 3D printing is getting insane. I've designed 3 plastic 3D printed parts that are flying in the past year. There are so many starving machine shops out there... I put out an RFQ on the cam plate and I had 4 companies beating each other up over price in under an hour. If a call an Asian manufacturing broker... the prices are laughable.

Second is my A&P training... Maintenance and ownership. I'm trying to make this thing so AS much as possible can be done without blowing it apart. Need to replace lifters, they are externally accessible. Oil pump... LRU. I want to include a pre-oiler/figure out if an external oil cycling system would be good... kind of like a battery tender but for oil, I'ts dry sump obviously so I figure good hydraulic QD fittings could be included. Maybe a few smart placed inspection ports.

Electronic ignition... No Magnetos...It's experimental. How many of you have taken apart a magneto and looked at that little I think its a #8-32 pan head phillips screw @ 6 inch-pounds that goes into a zinc housing that sets the breaker gap... not to mention plastic gears. Yeah. They work but I'm not about to make a custom magneto or rely on some NOS. Besides what I can do with a simple brain box stuffed in a nice 6061-T6 ECU housing with 38999 connectors and OEM Automotive ignition coil packs is pretty cool.

I think I want to start with a carburetor. KISS. I was talking about going nuts with a fuel management system but my GM buddy thinks that's currently beyond my scope of work. I really like the AeroVee AeroInjector but for proof of concept I bet a MA-4-5 will work. Most everyone I talk to that have a COTS system is set up for 4 or 6 cylinder. No love for Odd number radials. If you know of someone let me know.

As much as I want to fool with Supercharging, and turbos... I'm not going to for the first one. There may be a "mixing fan" in the induction manifold but that's it, nothing geared. Math says it should get about a half inch at most.

The crank is a single throw (short, stubby, much lighter than typical horizontally opposed), made up of multiple parts... assembled like a jet engine shaft. Hopefully I can couple it with a wooden/composite prop... I would like to see prop strike events to become a much lower cost ordeal. That I think right there is what scares me the most about typical aircraft engines... I can replace just about everything reasonably on a good $4k core, but if that crank or the cam is bad... I lost... I don't gamble. I want that issue to disappear.

Cam shaft is gone. Replaced with a cam plate that will be bathed in oil. I've got a friend that's a lubrication engineer and I've yet to get a verdict on going to a precipitation hardening stainless. No reason to use 1930's alloys. Hydraulic Roller lifters.

I want to say it's very conservative in it's design. It's 5 cylinders. Direct dive. I'm aiming for just under 200hp (I could still shift up to 250 but I think that's a bit much for an RV?) at 2700 RPM red line. No planetary gears... looking down the road so any "P" can work on it. I tried so very hard to get it the same width as an O-320 but its about 2 inches wider... and obviously round. It's a little under the weight of an O-320... I was hoping to go with a nylon induction housing (just about every GM product in the past decade) but I'm not sure it can survive behind an air cooled monster. By the time I have every bolt and bearing in there it will probably be about the same.

I would very much like to hear the thoughts of the community... maybe an outstanding maintenance issue or cost I haven't thought of that could be designed out.

What's your engine wish list?

What's put your plane out of annual or for sale that's engine related?

I'm going to make mine...If it works... I imagine I could make it a kit a la AeroVee. Once I get it near finalized, or actually get one built I'll let the cat out of the bag if there's interest... I think everyone's head would explode. It's really simple in concept. I'm tired of aviation being so ridiculously expensive I want to change that.

:eek:
 
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Love the concept. I can hear the groans and all the arm chair experts telling you it makes no sense, etc. But it puts the experimental back in experimental aviation.

Bravo.

Your point that modern manufacturing techniques are a key enabler to the feasibility of this is missed often in such discussions.

Now let?s hope it rumbles, spits, and coughs like a good old P&W.....
 
really cool.

I'm definitely not smart enough to be an armchair expert, but I will comment on one thing you said.

There are MO gas pumps right next to the 100LL pumps at two airports within 30 miles of here, current price $3.29 & $3.19 per gallon respectively.

Also, I have a buddy that lives on a grass strip who has a bulk tank and has it delivered. I think he told me that he's paying around $3.10, but I'm not sure how much he has to buy to get that price.

Not criticizing, just though that based on what you're trying to do, you might want to be aware that there's definitely a market for it.
 
Love your initiative. Wish I was smart enough to do stuff like that!
Sorry to hear your diesel/Jet A designs didn't work out. I still believe to keep GA sustainable/economical for the long term that eventually, not next week, there should only be one fuel pump at the airport.
Good luck!
 
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Two Cents Worth

Just under 200 hp with the weight of a 320? And a radial to boot!

My only take is why not bump up the HP to 250? I don't think there's a problem with too much horsepower!

Go for it...!
 
Might take a look at the Verner engines. People have been having great success with them and would prevent having to start from scratch, unless you?re dead set on that. I have a M14P on my Murphy moose and at 620 cu in, it?s pumping out right at 400 hp at 2950 and 35?. The supercharger breaks the fuel particles down from the pressure carb at high rpm. However, at cruise rpm of 1730-1940, it doesn?t do so hot and the spread on my top and bottom cylinders for CHT?s is 90 degrees. That?s a lot when my top cylinders are running nearly 400 in cruise, but it?s well known on these engines and everyone says to forget about it and just run it. I plan on working with Ross at some point to make a multi-port injection system that can be tuned for each cylinder. Bottom line is the droplets are falling out of suspension on the way to the cylinders. Gotta find a way to solve that.

I don?t think your plastic induction would be long lived. It gets pretty toasty behind all of those cylinders. It sounds like you have some good ideas, but judging from your other posts, this may be a bit out of your league. Just some brutally honest feedback. Take a look through the archives and you?ll see others with many more resources at their finger tips that have failed. I don?t say that to discourage, but perhaps your time and resources would be better spent elsewhere. Good luck!
 
Love the concept. I can hear the groans and all the arm chair experts telling you it makes no sense, etc. But it puts the experimental back in experimental aviation.

Bravo.

Your point that modern manufacturing techniques are a key enabler to the feasibility of this is missed often in such discussions.

Now let’s hope it rumbles, spits, and coughs like a good old P&W.....

That's why I posted. Bring it armchairs! I bet there are actually a lot of really smart people lurking in here... people that build airplanes for fun are generally not idiots. I'm trying to figure out what I may have missed.

But yeah...
Spark plug socket to drain oil out of the bottom, firing up big cloud of blue smoke... it's going to be cool.


really cool.


There are MO gas pumps right next to the 100LL pumps at two airports within 30 miles of here, current price $3.29 & $3.19 per gallon respectively...
bulk tank around $3.10

Not criticizing, just though that based on what you're trying to do, you might want to be aware that there's definitely a market for it.

WOW! That's cool. I'm in Phoenix AZ... I looked... There's a website I found that lists where to get mogas... the only place I could find had VP race gas in 30 gallon drums for stupid money.

Love your initiative. Wish I was smart enough to do stuff like that!
Sorry to hear your diesel/Jet A designs didn't work out. I still believe to keep GA sustainable/economical for the long term that eventually, not next week, there should only be one fuel pump at the airport.
Good luck!

Well... they didn't not work out they just got too complex for me. I discovered how complex a Bosch P-pump really is. If I had a good controls guy who could drive modern GM diesel injectors I would love to revisit that... but the programming behind that is way out of scope right now. Peak pressures are high, but they were not ridiculous.

...why not bump up the HP to 250?

Because it gets into the range where a harmonic pendulum damper for 3rd order torsional vibration would need to be made... that's not something ya get even remotely correct the first time out. Even at 200 horse I'm pretty concerned about it because of how BIG some of the parts are. There's a reason some of the other "Toy" radials out there are 7 or 9 cylinders and are still pretty small in HP. But I've got a Jacobs that whispers don't worry about it. Besides its more $$$, and probably another inch bigger round. I bet it could easily be Mk3.


would prevent having to start from scratch It sounds like you have some good ideas, but judging from your other posts, this may be a bit out of your league. Just some brutally honest feedback.

Started from scratch a long time ago, and I admittedly know very little about Propellers. Well... if it is out of my league, I haven't figured it out yet ;). Mechanically everything is worked out... there's detail design on the case left to do. I KNOW I can make mine. Is it viable to put on the front of an aircraft... There is a lot of gas and probably countless teardown/rebuilds between here and there. I'm sure there will be bugs, but I've done just about everything I can think of to minimize total failures. I've got a Jacobs, and an o-320's I've torn apart, had parts scanned to reverse engineer to understand "their how and whys"... and again tons of design books. There's one in particular from 1942 discarded from the Christler design library that's basically a total design analysis of a Wright Cyclone they were under contract to build. I basically followed the book... I'm on the last chapter. Stumbling on that made this happen.
XLaV4tVm.jpg

Besides... It's Arizona and I've been inside for most of the summer.
 
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... and again tons of design books. There's one in particular from 1942 discarded from the Christler design library that's basically a total design analysis of a Wright Cyclone they were under contract to build. I basically followed the book... I'm on the last chapter. Stumbling on that made this happen.
XLaV4tVm.jpg

Besides... It's Arizona and I've been inside for most of the summer.

Oooooooo! I love those old books. Back in the day the authors tended to explain in terms familiar to big dummies like me, rather than the current practice....three pages of equations, followed by "Thus it can be seen..."
 
Oooooooo! I love those old books. Back in the day the authors tended to explain in terms familiar to big dummies like me, rather than the current practice....three pages of equations, followed by "Thus it can be seen..."

EXACTLY!

And where there are equations... they list what all the variables are! Now days you're lucky to get a page at the start of the book... bonus at for each chapter.

Nope... Solid description of the variables and how to manipulate the equation!
 
New Engine

Congratulations on jumping into the deep end of the pool!

I can recommend another book if it's not already in your library, should be available used from abebook.com or similar used booksites:

"Aircraft Engine Design" by Joseph Liston, McGraw-Hill. Mine is a first edition 1942. The best book on the subject I have ever seen.

If you haven't already, I suggest you study the history of recent new engine manufacturers, such as Rotec and Jabiru. I think both designs are fundamentally sound, but their service history includes a LOT of failures. To me this points to a lack of (ground) testing and a lack of development. If you read the history of the major radial (and vee) engine manufacturers in the 1930s and 1940s you'll note how much testing they did and how many failures they overcame before they were put into service.

The one area I have noticed that designers/manufacturers of new engines (or converted auto engines for that matter) don't pay enough attention to is torsional vibration testing, so make sure you do a good mass elastic and torsional vibration analysis. This is way easier to do with modern computer tools than it was in the 1930s. This also ties in with propeller testing as the engine and propeller form a mass elastic system. You should strongly consider getting the major propeller manufacturers to do a vibration survey of the propeller once you get to the testing stage.

My wish for a radial engine for RVs (although is wouldn't be for my RV-9A)
-7 cylinders. (I've heard a 5 cylinder radial and it doesn't sound good. 7 cylinders will run smoother)
-Fuel injection. Simple mechanical system like Bendix. Eliminates carb icing and mixture distribution problems. Would eliminate the "supercharger" and
weigh less and be simpler.
-Constant speed propeller provision
-Provision for two alternators (main 60A and backup 30A)
-Valve seats designed for mogas
 
Solution

As a fellow engineer, I will ask you a serious question:
What problem are you trying to solve?

Also... Engine Wish List
Cost: $100 per hp
Longevity: 30yrs or 3000 hours with only oil, filter, spark plugs (like my cast iron Kohler mower engine)
Weight: Less than a Lycoming with the same HP
Efficiency: Better than a Lycoming
 
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Congratulations on jumping into the deep end of the pool!

I can recommend another book if it's not already in your library, should be available used from abebook.com or similar used booksites:

"Aircraft Engine Design" by Joseph Liston, McGraw-Hill. Mine is a first edition 1942. The best book on the subject I have ever seen.

If you haven't already, I suggest you study the history of recent new engine manufacturers, such as Rotec and Jabiru. I think both designs are fundamentally sound, but their service history includes a LOT of failures. To me this points to a lack of (ground) testing and a lack of development. If you read the history of the major radial (and vee) engine manufacturers in the 1930s and 1940s you'll note how much testing they did and how many failures they overcame before they were put into service.

The one area I have noticed that designers/manufacturers of new engines (or converted auto engines for that matter) don't pay enough attention to is torsional vibration testing, so make sure you do a good mass elastic and torsional vibration analysis. This is way easier to do with modern computer tools than it was in the 1930s. This also ties in with propeller testing as the engine and propeller form a mass elastic system. You should strongly consider getting the major propeller manufacturers to do a vibration survey of the propeller once you get to the testing stage.

My wish for a radial engine for RVs (although is wouldn't be for my RV-9A)
-7 cylinders. (I've heard a 5 cylinder radial and it doesn't sound good. 7 cylinders will run smoother)
-Fuel injection. Simple mechanical system like Bendix. Eliminates carb icing and mixture distribution problems. Would eliminate the "supercharger" and
weigh less and be simpler.
-Constant speed propeller provision
-Provision for two alternators (main 60A and backup 30A)
-Valve seats designed for mogas


-I have Liston on my desk... not on the bookshelf!
-I've not heard a 5! I would like a 7, but what I'm doing it's entirely too big. Maybe Mk3 or 4.
-I would love to have fuel injection... I think it would actually be really easy to put a bendix system on it after the fact. I'll have to ask an older wiser A&P.
-Torsional vibration is forefront on my mind! There is a Quip in Liston that most TV analysis is not needed once appropriate accounting for bearing speeds... driving crank diameters is taken care of. I'm getting pretty close to having everything in the crank chain to having proper mass. I do still need to do a vibration study... but It's probably not going to show anything, and It's not to late to change something if there is a natural resonance of concern.
-there will be TONS of ground testing. My GM friend is a Test engineer and is very much looking forward to that phase.
-...constant speed prop. I don't know. I will probably start with a fixed pitch. I like the concept of a manual variable pitch-see propeller thread.
-2 alternators is the plan.
-I would seriously consider it, easy enough swap... but I don't have access to mogas. So I'm moving forward with standard 110LL materials.
 
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As a fellow engineer, I will ask you a serious question:
What problem are you trying to solve?

Also... Engine Wish List
Cost: $100 per hp
Longevity: 30yrs or 3000 hours with only oil, filter, spark plugs (like my cast iron Kohler mower engine)
Weight: Less than a Lycoming with the same HP
Efficiency: Better than a Lycoming

Problems:
1: boredom/entertainment/because I can :D
2: Cost. I cant bring myself to spend $4k on an engine core, time in the machine shop, new jugs, and still run the possibility of needing a new crank for $15k or cam for $10k. They priced themselves out of my interest to play.
3: Easier to work on/maintenance
4: $. **IF** I can make this happen... My wife and I are pretty good at running a machine shop. It would be nice to have our own "product".

Cast iron Kohler. Ya know... I went down that thought... I might revisit that one day. One of my favorite examples M240 machine gun. FN Herstal made a lightweight version using exotic metals. I forgot how much weight they knocked off but it was a lot. Barrett of .50bmg fame, used CAD and FEA to get rid of un-needed steel and made a lightweight M240 out of steel... that was lighter than FN's Titanium gun. That's inspired me on a few occasions. Doesn't do too much for heat rejection however.

There is a lot I can do with FEA analysis.
 
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Some folks in Pennsylvania are/were attempting to recreate the Warner radial using modern machining methods. I think the project may be dormant right now because of another commitment. I bring it up only because when visiting the shop, the time/cash investment in CAD, tools, and fixtures appeared to be really significant, even using a very capable machining center.

I was involved with a fixed pitch version of the M14. Did a torsional analysis of both geared and solid shaft versions. Pretty sure you'll need to also. I don't think you'll be able to get stiffness high enough to push the F1 above the operating range...but that's gut, not analysis.
 
Some folks in Pennsylvania are/were attempting to recreate the Warner radial using modern machining methods. I think the project may be dormant right now because of another commitment. I bring it up only because when visiting the shop, the time/cash investment in CAD, tools, and fixtures appeared to be really significant, even using a very capable machining center.

I was involved with a fixed pitch version of the M14. Did a torsional analysis of both geared and solid shaft versions. Pretty sure you'll need to also. I don't think you'll be able to get stiffness high enough to push the F1 above the operating range...but that's gut, not analysis.

Funny you bring that up. :eek: The fella that has the TC for Warners, I asked him to take a stab at making the cad models for him back in '13. He previously owned the greatlakes TC... I have the 2t-1a-2 plans set and want to put one of these on the front that too. He still has pictures on his website I took of a local guys warner that's on his Waco RNF.

xJo07BZm.jpg

Old model...My modified Great lakes with a longer cockpit... I barely fit in one from the 70's. I still want to put composite wings on that thing. Side note that's where I left off on a 12valve cummins based radial!

He sent me some un-serviceable heads and blueprints. I had them 3D scanned and I got stuck on the fins... I was really trying to replicate the print and original castings perfectly. If I gave them to my dad to make casting cores out of wood... he could have done it, but at the time I wasn't up to modeling it and was taking a long time... I was working full time and then some back then too. We had a bit of a falling out unfortunately. I don't blame him. But again knowing what I know now, what he wanted to do is outside of the TC for that engine. I had a casual chat with some guys over at the MIDO office about that project... they said they would have never approved that head being fully CNC'd. The approved alloy has to be cast, and the prints are very specific about what is as cast and what is machined. They said we could have done it under FAR21.9(5) as an owner produced part but would have never been approved for sale. I bet that's where he got stuck.
 
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With respect to your original question about how many people use auto fuel STC's, there are two aspects to this answer.

1) for type certificated aircraft, there are a lot of people who burn mogas. If you don't believe me, just spend awhile talking to Bonanza owners. The ones who own the E225 engines are VERY happy to be able to burn mogas

2) over here in this crowd, I think the more appropriate response would be along the lines of... "STC? We don't need no stinkin' STC!" :D
Honestly, I have two amateur-built airplanes and they both burn mogas, one of them almost exclusively mogas. It IS a big deal in keeping direct operating costs under control.

Spend a little time looking at the challenges faced by the current crop of "new manufacture" radial engines. They are not without their challenges.

Also, your comments about going with a carb bear some scrutiny and perhaps reconsideration. I would encourage you to spend a bit of time talking to Ross Farnham of Simple Digital Systems. He frequently shares his copious knowledge on this forum. You might find yourself far ahead of the game to buy an off-the-shelf electronic injection and ignition system like the ones SDS manufacture as their tunability might help you get around engine running issues that otherwise would take considerable mechanical re-design to overcome.

As for the compression-ignition heavy fuel engine, it might work better with electronic ignition and electronic injection as well.

Here's wishing you good success in your pursuit.
 
With respect to your original question about how many people use auto fuel STC's, there are two aspects to this answer.

1) for type certificated aircraft, there are a lot of people who burn mogas. If you don't believe me, just spend awhile talking to Bonanza owners. The ones who own the E225 engines are VERY happy to be able to burn mogas

2) over here in this crowd, I think the more appropriate response would be along the lines of... "STC? We don't need no stinkin' STC!" :D
Honestly, I have two amateur-built airplanes and they both burn mogas, one of them almost exclusively mogas. It IS a big deal in keeping direct operating costs under control.

Spend a little time looking at the challenges faced by the current crop of "new manufacture" radial engines. They are not without their challenges.

Also, your comments about going with a carb bear some scrutiny and perhaps reconsideration. I would encourage you to spend a bit of time talking to Ross Farnham of Simple Digital Systems. He frequently shares his copious knowledge on this forum. You might find yourself far ahead of the game to buy an off-the-shelf electronic injection and ignition system like the ones SDS manufacture as their tunability might help you get around engine running issues that otherwise would take considerable mechanical re-design to overcome.

As for the compression-ignition heavy fuel engine, it might work better with electronic ignition and electronic injection as well.

Here's wishing you good success in your pursuit.

I sent Ross at SDS a message last week. The hardware he uses cant handle the timing spacing on a radial.
 
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And another request to consider at least an option of a hydraulic constant speed prop. The way Lycoming does that, it's actually field-changeable between the CS and FP. It doesn't need to go back to the manufacturer.

Dave
 
And another request to consider at least an option of a hydraulic constant speed prop. The way Lycoming does that, it's actually field-changeable between the CS and FP. It doesn't need to go back to the manufacturer.

Dave

To be honest I don't really know what's involved to do it correctly at this time. I don't think I have a drilled crank I can interrogate ... I'll look but even with that... isn't there a mounting pad for a prop governor or something I would need to include?
 
So, someone mentioned that the current new mfg radials suffer from a testing problem.


~IF~

I got my personal engine up and running and "it's good" at what point do I try to make it a product? What is "it's good"?


I was going to write a lot more, but I think leaving this open ended and see what happens.
 
So, someone mentioned that the current new mfg radials suffer from a testing problem.


~IF~

I got my personal engine up and running and "it's good" at what point do I try to make it a product? What is "it's good"?


I was going to write a lot more, but I think leaving this open ended and see what happens.

Good question. And as with most things, it depends. If you?re able to make a working version, there will be a handful of people that might buy one just to be unique. I am guessing that what you?re getting at is how ?good? does it need to be to be profitable. As someone currently in sales, my question to any new manufacturer is what is your value proposition; what is the unmet need in the market you are hoping to fill and what proportion of the overall market do you estimate has that need?

If you are looking at competing in the broad experimental engine market, the answer is easy enough; it has to be competitive with an off the shelf Lycoming/clone in terms of acquisition cost, ease of installation, maintenance cost, power-to-weight ratio, reliability and economy. You would probably not have to meet or beat Lyco in all those areas (cool factor of a radial and all :D), but the closer you get, the more buyers you get. The tough ones are maintenance cost and reliability because they take time to demonstrate.


Best of luck,
 
T.... isn't there a mounting pad for a prop governor or something I would need to include?

Yes, you need to be able to mount a prop governor. Look up how they work because there's more to it than merely having a drive shaft connection to it.

Dave
 
Good question. And as with most things, it depends. If you?re able to make a working version, there will be a handful of people that might buy one just to be unique. I am guessing that what you?re getting at is how ?good? does it need to be to be profitable. As someone currently in sales, my question to any new manufacturer is what is your value proposition; what is the unmet need in the market you are hoping to fill and what proportion of the overall market do you estimate has that need?

If you are looking at competing in the broad experimental engine market, the answer is easy enough; it has to be competitive with an off the shelf Lycoming/clone in terms of acquisition cost, ease of installation, maintenance cost, power-to-weight ratio, reliability and economy. You would probably not have to meet or beat Lyco in all those areas (cool factor of a radial and all :D), but the closer you get, the more buyers you get. The tough ones are maintenance cost and reliability because they take time to demonstrate.


Best of luck,

You certainly have a sales point of view! I was thinking more in terms of reliability... how much testing I should do. It would take me admittedly many years to clock 2000 hours on an engine.

BUT! Lets play in your world for a bit because it's a good point.

Unmet market need: To me it's Value. I know manufacturing. From a purely manufacturing perspective I do not understand how a big VW engine should cost $30k+. I look to the used market and see them go for about $6k for a good core. Then maybe provided things go well one could have a good working engine in the $12-15k range. I think that's what it should really cost. That's still expensive... but reasonable, and the ballpark I'm playing in. If things don't go well, Crank and camshafts are big ticket items that are in my opinion EXTREMELY overpriced. That's where I'm at right now... I'm terrified of buying a used engine/core.

A radial removes the expense associated with those items. A radial crank is 1 throw, smaller, is modular. The cam, is a whole different animal. I've already had the cam quoted at under $1000... and could easily retail around there.

The other thing I include in value is continued maintenance. Traditional engines seem to be designed to self destruct if they are not run at least once a week. I would love to fly once a week, but that rarely happens. I'm trying to design in features that would decrease the impact of disuse. I'm keeping the system architecture VERY similar to a lyco-cont-clone. Anyone who has worked on those, could be given my manual and be just fine.

-My MAIN goal is Acquisition cost for my engine kit will be in the $10k-$20k range.
-It's a kit, that would cater to experimental crowd, and remove assembly cost on my end.
-Being a kit, the owner/builder should be very comfortable doing just about anything as far as maintenance.
-It's a 200 hp AIRCRAFT engine. not-geared, not an RC plane motor, Not a car engine never intended to be run at 100% duty cycle.
-I'm designing features to meet accepted 2000 hours TBO
-I'm trying to design out cost.
-Power to weight will be unbeatable by anything other than another radial.
-It's a Radial

I hope all of that would be appealing. I could see going as far as doing an entire firewall forward kit... to include engine mount, cowling... not sure what else because I haven't gotten that far on my RV8 yet!
 
Yes, you need to be able to mount a prop governor. Look up how they work because there's more to it than merely having a drive shaft connection to it.

Dave

I'll look into it... Anybody that knows more have a specific model that would be good for a 200 hp RV8 I could research and figure out what it needs?
 
New Engine Testing

So, someone mentioned that the current new mfg radials suffer from a testing problem.
~IF~
I got my personal engine up and running and "it's good" at what point do I try to make it a product? What is "it's good"?
I was going to write a lot more, but I think leaving this open ended and see what happens.

The FAA regulations are a good place to start. If you can meet them, you're in the same league as Lyclones.
https://www.ecfr.gov/cgi-bin/text-i...mc=true&node=pt14.1.33&rgn=div5#se14.1.33_149

Part 33 Airworthiness Standards - Aircraft Engines

?33.49 Endurance test.
(a) General. Each engine must be subjected to an endurance test that includes a total of 150 hours of operation (except as provided in paragraph (e)(1)(iii) of this section) and, depending upon the type and contemplated use of the engine, consists of one of the series of runs specified in paragraphs (b) through (e) of this section, as applicable. The runs must be made in the order found appropriate by the Administrator for the particular engine being tested. During the endurance test the engine power and the crankshaft rotational speed must be kept within ?3 percent of the rated values. During the runs at rated takeoff power and for at least 35 hours at rated maximum continuous power, one cylinder must be operated at not less than the limiting temperature, the other cylinders must be operated at a temperature not lower than 50 degrees F. below the limiting temperature, and the oil inlet temperature must be maintained within ?10 degrees F. of the limiting temperature. An engine that is equipped with a propeller shaft must be fitted for the endurance test with a propeller that thrust-loads the engine to the maximum thrust which the engine is designed to resist at each applicable operating condition specified in this section. Each accessory drive and mounting attachment must be loaded. During operation at rated takeoff power and rated maximum continuous power, the load imposed by each accessory used only for an aircraft service must be the limit load specified by the applicant for the engine drive or attachment point.

So for the endurance test, you only have to run for 150 hours, not to TBO.

In addition section 33.43 deals with vibration

This is not much different from Vans philosophy. Design and test to the appropriate FAA standards because they have been proven with time (and written in blood, hope that's not too melodramatic, but it's true). You don't actually have to get the engine certified (impossibly expensive) but if you have performed the tests and documented them then "it's good".
 
The FAA regulations are a good place to start. If you can meet them, you're in the same league as Lyclones.
... ...

This is not much different from Vans philosophy. Design and test to the appropriate FAA standards because they have been proven with time (and written in blood, hope that's not too melodramatic, but it's true). You don't actually have to get the engine certified (impossibly expensive) but if you have performed the tests and documented them then "it's good".

Sounds good to me. Still a $10k fuel budget.
 
Radials

Very interesting the potential for 3 radial RV-8's Brian Kellie's , mine, and yours
Do you have any pictures of your prototype? How does yours compare to the Rotec 3600?
 
Very interesting the potential for 3 radial RV-8's Brian Kellie's , mine, and yours
Do you have any pictures of your prototype? How does yours compare to the Rotec 3600?

It's mostly solidworks files at the moment. I wan't to get a little further along before I let it drop... if it gets that far. I know the core geometry is good... the "concept" behind it is good.

Mine...vs 3600
-direct drive, not geared.
-has 4 less cylinders.
-Almost 2x the displacement.
-50 more horsepower predicted.
-roughly Same weight... I hope.
 
Best wishes for a successful outcome, and really looking forward to seeing your prototype when the time comes.
 
Best wishes for a successful outcome, and really looking forward to seeing your prototype when the time comes.

Thanks! I cant hardly wait too. It seems like I design a part, write a report to justify what I did... decide I could do it better, update the report.

I've got a pretty good group around me that's going to review everything before I sign a PO.
 
Fantasy engine

At 300 HP, minimum 6 cylinders ( for prop pulse, torsion, longevity etc)
Turbo charged, compression ignition (fuel cost, availablity)
Obviously reliability, cost and size.
Rather have a 300 horse power plant derated to 220 or 250 than
Pushed hard to make maximum HP.
 
Fantasy engine

Direct drive and maximum RPM of 2600, after that
airfoil efficiency degrades.
 
The way I'm playing... If I stepped up to 7 cylinders it would be a gentle NA, Direct drive, 2700rpm, 315hp. I don't have that kind of gas budget for the plane that would go on. If you do would be glad to make one :)

But yes... a 4 stroke radial, which requires odd numbers.

Maybe someday I'll build a Conwing l-16 Seaduck :cool:
 
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I know nothing about VVT solenoids. :confused:

VVT solenoids as used to control hydraulic cam phasers for variable valve timing systems. Relatively widely available these days and pretty reliable. Yes, you'd need electronics but you can delete the mechanical drive required for a conventional governor.
 
A double-row six would work and probably offer better packaging than a 7-cylinder single-row.

Then the case is twice as big, the crank is twice as big, twice as many lifters and there are two cams. Those are all high value items.

By the time I would be tempted to do a 2 row it's going to be a 14 cylinder... and that's huge. I'm not particularly interested in that game. With that fuel flow ya might as well start looking at turbines. IMHO
 
VVT solenoids as used to control hydraulic cam phasers for variable valve timing systems. Relatively widely available these days and pretty reliable. Yes, you'd need electronics but you can delete the mechanical drive required for a conventional governor.

Just watched a youtube about them... Maybe there's something there but I'm not an electrical guy, and not where my passion is at right now. Not saying no... but it's already going to be a struggle getting this first one into reality.
 
Is a double row 6 really two threes or do you mean two sixes, in which case it cannot be a four stroke.
Best of luck I really like the sound of a radial, but have hardly ever flown one.
 
A double-row six would work and probably offer better packaging than a 7-cylinder single-row.

Again, it won't work. A four-stroke radial must have an odd number of cylinders on each bank. You could do two rows of five, or two rows of seven.



Personally the thought of a radial with EFI gives me the giggles. I'd love to pair it with either a slicked-up composite traveling airframe or a polished metal one with retro styling (but still good drag reduction).
 
I'm glad someone posted the FAA test requirements for piston engines.

Oh my goodness, are those ever lenient, even pathetic, test requirements.

On commercial jet aircraft engines, one has to run several thousand "C" cycles on the engine prior to certification. A "C" cycle is something like this: Idle, Throttle burst to max T/O, hold time, reduction to cruise power, hold time, then a smaller throttle burst representing thrust reverse, then a throttle chop to idle with hold time. Then repeat.

The idea is to put fatigue cycles on the engine as if it had run thousands of actual flights, by simulating the accels and decels in a real flight, but shortening the cycle time dramatically by removing excessive hold times, especially the many hours spent at cruise. Hold times typically are set just long enough to stabilize temperatures.

This testing concept is premised on the fact that engine hardware failures result from mechanical and thermal/mechanical fatigue, which can only be simulated by putting the same number of stress cycles on the hardware as in real flight cycles.

A piston engine that runs 150 hours in a test cell, and has not simulated flight cycles in any meaningful way, has not even come close to demonstrating that it can make it 2000 hrs. in the real world. If new engine entrants feel they can do the FAA minimum testing and make it in the real world, this may explain why some have field failures and eventually go out of business...

The good news is Lycomings have many decades of service to demonstrate they can, if maintained, usually make it to TBO. The bad news is, we rarely get any new technology from traditional aircraft engine manufacturers, even with these remarkably lenient test requirements.

-Paragon
Cincinnati, OH
 
New Engine

I'm glad someone posted the FAA test requirements for piston engines.

Oh my goodness, are those ever lenient, even pathetic, test requirements.

I only posted the general paragraph (a)of the endurance test. I hope you used the link to read the entire section, the actual test sequences are contained in paragraphs (b) through (e). Note that during the tests, the cylinder head temperatures are to be held at the maximum limiting temperatures and the oil is to be held at the maximum limiting temperature.

The purpose of engine testing is to subject the engine to a severe but time limited operation that ensures a reasonable chance of achieving TBO. A 2000 hour test does not make sense.

Although piston engines and turbine engines are both heat engines the architecture, operation, and limiting conditions are completely different, so I expect the turbine test procedure to be completely different.

The FAA engine test has evolved over the last hundred years. The OP asked what was would be a criteria to decide if his engine was "it's good". I suggested the FAA test would prove this.

I suspect that the engine "manufacturers" of new engines that have had early field failures have not even done the FAA endurance and vibration test.
 
I'm glad someone posted the FAA test requirements for piston engines.

Oh my goodness, are those ever lenient, even pathetic, test requirements.

On commercial jet aircraft engines, one has to run several thousand "C" cycles on the engine prior to certification. ....

The idea is to put fatigue cycles on the engine as if it had run thousands of actual flights, by simulating the accels and decels in a real flight, but shortening the cycle time dramatically by removing excessive hold times, ...

A piston engine that runs 150 hours in a test cell, and has not simulated flight cycles in any meaningful way, has not even come close to demonstrating that it can make it 2000 hrs. ....
-Paragon
Cincinnati, OH

I wonder if the XP-382/XP-400 engines ran 150 hrs on a test stand, with the required conditions? If so, and then their subsequent failures, shows how inadequate this testing regimen is. If it takes more than 150 hrs for a poorly designed crankshaft to propagate a crack long enough to fail, then the test isn't very useful.
 
Using COTS cylinders?

I've often wondered about the idea of assembling a radial engine with commercial off-the-shelf cylinders.

One could build a 7-cylinder engine using the ubiquitous Continental O-200 cylinders, and have a displacement of 350 cu. in. Should develop in the neighborhood of 170 hp. Or a 9-cylinder engine with 450 cu. in. that would make something like 220 hp.

Is there anything fundamentally different about cylinders for radials that would make this idea not work?
 
I'm glad someone posted the FAA test requirements for piston engines.

Oh my goodness, are those ever lenient, even pathetic, test requirements.
To be fair, the "endurance test" specified in 33.87 for turbine engines says:
§33.87 Endurance test.

(a) General. Each engine must be subjected to an endurance test that includes a total of at least 150 hours of operation and, depending upon the type and contemplated use of the engine, consists of one of the series of runs specified in paragraphs (b) through (g) of this section, as applicable. For engines tested under paragraphs (b), (c), (d), (e) or (g) of this section, the prescribed 6-hour test sequence must be conducted 25 times to complete the required 150 hours of operation. Engines for which the 30-second OEI and 2-minute OEI ratings are desired must be further tested under paragraph (f) of this section. The following test requirements apply:...

I suspect that things like market requirements (almost nobody wants an engine with a 150 hour TBO), ETOPS requirements, and simply testing the engines enough to meet all the other myriad requirements and means of compliance and everything else will have the engines running far longer than 150 hours.


A piston engine that runs 150 hours in a test cell, and has not simulated flight cycles in any meaningful way, has not even come close to demonstrating that it can make it 2000 hrs. in the real world. If new engine entrants feel they can do the FAA minimum testing and make it in the real world, this may explain why some have field failures and eventually go out of business...

I also seriously doubt that anyone goes out to build a new engine thinks they can build one example of an engine, manage to keep it from falling apart for 150 hours, and call it certified. I suspect most new entrants (especially in the piston field) severely underestimate the time and costs associated with obtaining a new type certificate. As you almost certainly know, it's not good enough just to meet the cert requirements. You have to show that you meet the cert requirements the way the FAA wants to be shown.

The good news is Lycomings have many decades of service to demonstrate they can, if maintained, usually make it to TBO. The bad news is, we rarely get any new technology from traditional aircraft engine manufacturers, even with these remarkably lenient test requirements.

The rise of the turbine engine mostly killed significant development of the aviation piston engine. As with most things, bigger airplanes and their bigger engines provide the opportunities for bigger profit margins, which make available more R&D funds. Small turbines grew from the advances on big turbines; those small turbines are taking an increasing share of the market once held by large piston engines. The remaining piston market is going to ever-smaller airplanes which don't have the revenue potential that turboprops do.

Couple that with ever more stringent FAA requirements (both the regulations, and all the supporting "stuff" that goes along with them) and you have a mostly stagnant certified piston engine market. Most of the major improvements we've seen have come in the form of fuel and spark delivery in the experimental market, or in a handful of brand-new engines, only one of which (Rotax) comes to mind as having made major commercial success.

Basically, the cost to continue making the same-old same-old, perhaps with minor changes, is more or less down to recurring costs, the R&D having been amortized a long time ago. But developing something new takes large piles of cash that have to be made up over a pretty small number of sales.
 
I've often wondered about the idea of assembling a radial engine with commercial off-the-shelf cylinders.

One could build a 7-cylinder engine using the ubiquitous Continental O-200 cylinders, and have a displacement of 350 cu. in. Should develop in the neighborhood of 170 hp. Or a 9-cylinder engine with 450 cu. in. that would make something like 220 hp.

Is there anything fundamentally different about cylinders for radials that would make this idea not work?

Nailed it. That's what I'm doing. superior 0-320 jugs. I've got a whole mess of them. Along with junk yard Jacobs, and P&W R-1830, GM LS-3 to investigate what I need to do. I'm basically reverse engineering the design of an o-320 to figure out what their design parameters are and applying that to this guy.
 
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Having been involved in a couple engine development projects eons ago, I can't agree that setting a longer TBO than what's been actually demonstrated on the dyno or test stand is valid nor can FEA models be trusted with certainty without actual running validation.

I can think of one popular aircraft engine, which has a certified version as well as Experimental versions, where early versions wouldn't even go 100 hours in normal use without the engine going south. Passed the tests but was junk in the real world with multiple deficiencies.

My recommendation is to pound on the prototype mercilessly across the engine rpm and load range at max temps and then run at least 150 hours at full power before thinking it's ok to fly yourself. If you're selling to the public, quadruple this figure.

Projected TBOs are meaningless IMO until at least one example as achieved that hour figure with no issues, yet I see almost all new manufacturers posting them, usually before the design has even run yet. Complete nonsense in my view.
 
Having been involved in a couple engine development projects eons ago, I can't agree that setting a longer TBO than what's been actually demonstrated on the dyno or test stand is valid nor can FEA models be trusted with certainty without actual running validation.

I can think of one popular aircraft engine, which has a certified version as well as Experimental versions, where early versions wouldn't even go 100 hours in normal use without the engine going south. Passed the tests but was junk in the real world with multiple deficiencies.

My recommendation is to pound on the prototype mercilessly across the engine rpm and load range at max temps and then run at least 150 hours at full power before thinking it's ok to fly yourself. If you're selling to the public, quadruple this figure.

Projected TBOs are meaningless IMO until at least one example as achieved that hour figure with no issues, yet I see almost all new manufacturers posting them, usually before the design has even run yet. Complete nonsense in my view.

Yes to all of that. I'm not seeking certification anytime soon.
 
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