New engine.

[Roarks]

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. 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.

[rbibb]

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.....

[Desert Rat]

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.

[Mudfly]

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!

[Hwood]

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...!

[Timberwolf]

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!

[Roarks]

Originally Posted by rbibb

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.

Originally Posted by Desert Rat

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.

Originally Posted by Mudfly

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.

Originally Posted by Hwood

...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.

Originally Posted by Timberwolf

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.

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

[DanH]

Originally Posted by Roarks

... 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.

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..."

[Roarks]

Originally Posted by DanH

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!

[terrye]

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