Thanks to Everyone Who Voted for My Engine !

[RodRico]

The results are in! My entry was in the Top 100 overall (of 868) and the Top 5 in the Aerospace and Defense category (of 115). The judging panel included 76 experts in their field from around the world. Though winning is always gratifying, I’m happy with the result. Thank you to all who voted!

By the way, the design continues to evolve based on inputs from my consultant and my own efforts to focus tightly on the aviation market (which will likely be last to be disrupted by battery electric systems), reduce risk, and cut prototyping costs. The first prototype will be a 50cc engine of 4.75" diameter and 3" thickness (including air cleaner and fuel injectors but not the electric motor/generator) having 8 cylinders completing 6 cycles each per revolution of the output shaft producing 3.3 HP at 2,626 RPM (low to eliminate the need for a propeller reduction unit) with 55% efficiency at up to 18,000 foot altitude. The engine will be machined using the $5,000 5-axis Pocket NC V2 mill and demonstrated using an off-the-shelf radio-controlled RQ-7 model (about 1/2 scale).

Many aspects of the design have come into clearer focus as I've continued working. I'll now concede that the engine is variable compression, that the use of two pistons for the HCCI process is not required from a thermodynamic perspective (the second piston serves primarily to effect a piston gated port in a position that facilitates uniflow scavenge while simultaneously facilitating rapid piston motion via its low mass). Note peak pressure is now below 220 bar to prevent ignition of lubricating oil, max temperature is below 2100K to prevent NOx formation, and ignition occurs after compression is complete in all cases.

https://contest.techbriefs.com/2017/entries/aerospace-and-defense/8090

 

[enginesrus]

A VF3 Haas (or some other brand) size machine is what you need and actually a 5 axis would be nice. Don't go too small as you can always run small parts on a big machine but not the other way around. The larger than needed machine can be used for special tooling needed to hold the parts etc.

 

[RodRico]

enginesrus,

If I elected to go into production using my own equipment, something like the Haas VF3 is a possibility. All I'm doing right now is make a proof of concept prototype.

In your opinion, is the PCNC 770 or 1100 good enough for a 4.75" diameter, 3" thick, prototype? If not, I will likely have to send the proto work out. Doing so, however, will deny me the education in design and manufacturing that comes with struggling through it myself, so I'd really like to find a suitable answer in a small mill for a home shop. There are many videos from respected machining channels on YouTube showing the PCNCs doing professional grade work in stainless and titanium without a hint of chatter and visibly clean surface finish.

I honestly hadn't considered fixtures yet, and your suggestion to go bigger than the minimum so I can build them is a good one. I'll take that into account. You were likely referring to fixtures needed to support machining, but the larger engine stand (with torque reaction gauge, fuel tank, oil tank, electric engine for starting and motoring, etc.) needs to be built as well, and I think it's going to dominate the size requirement.

Rod

 

[SwinnyGG]

You're coming at this from the wrong angle, in my opinion- the overall size of your completed assembly isn't all that important; what matters most is what tolerances you need to hold, and how close those tolerances are to the limits of the machine(s) chosen to do the work.

It sounds like you have very little, possibly zero, machining experience (from your descriptions of 'struggling with [manufacturing] yourself'.

Holding tight tolerances on CNC machines is affected by many things. A few of them are:

1) Stiffness of the machine, and quality of the controls. The smaller and cheaper the machine, the less you get of both.

2) The quality and correct use of the tooling. Good tools are expensive, and having the right tool for each individual job is important.

3) The skill of the machinist. CNC machines do not magically produce perfect parts- it takes skill to make any machine, even a computer controlled one, produce parts with close tolerances.

Based on the work ethic you've shown by developing this concept, I do not think you lack anything in the area of motivation to learn what you'd need to know to produce the parts you need. I am in no way trying to be insulting- but my suggestion would be to send this work out.

I highly doubt you will save money by doing this yourself; you may be targeting a machine that only costs six or seven thousand dollars, but the machine will include zero quality tooling and zero fixturing. That stuff is expensive.

I would expect an experienced machinist, starting with zero tools, to have to spend at least the cost of one of those machines on fixturing/cutting tools/other bits before it would be capable of producing useable internal engine components- and that is assuming someone with a lot of experience machining, who is going to be able to get the setups and fixturing correct on the first try, and isn't going to break a bunch of tools due to inexperience, or waste a bunch of material on fixture designs that don't work out, etc.

I'm not trying to discourage you- but if you've never run a manual machine before, let alone a CNC machine, you're going to break or otherwise ruin a LOT of tooling and waste a LOT of expensive material before you figure it out.

Even when you get to the point where you can make a part look like the drawing- do you have the capability to measure parts with close tolerances so that you know they will fit properly and not destroy your prototype? To get there you'll need a real metrology scheme and equipment- hand calipers and scales won't get you there. You're talking another couple thousand dollars of hardware, and another critical skill that you, at present, do not have.

You have a relatively simple decision to make: send this work to someone competent (which is another discussion- choose carefully) and have your prototype assembled in as little as a few weeks; or spend a LOT more money and a huge amount of time to be able to say you made everything yourself.

How much time do you have to actually be out in a/your 'machine shop' working?

It takes people years to become even remotely competent when they're doing it 40 hours a week. Are you willing to wait a year or more to be able to produce parts precise enough to work as you've designed?

 

[RodRico]

jgKRI,

Doesn't size matter in terms of tolerance stack-up?

I'm aware of the challenges I would be facing attempting to do the whole job myself. I plan to take the CNC class at my local community college just to get better acquainted with methods to better inform the final design and plan to visit a local machine shop to get an estimate before doing anything.

You may be surprised, by the way, to hear I don't have a lot of close tolerances in the refined design (not the one I discussed in the Create The Future Contest entry) and my stack-up paths are short. I have always assumed I would have to send the cams out but, beyond those, everything is actually pretty loose so to speak. I'll certainly need clean finishes everywhere and I may end up outsourcing the cylinder boring as well (to ensure good concentricity and finish). If I do end up doing any of this myself, I'll go very slow; I'll start with wax just to get some basics out of the way then move up to 6061 before tackling 7075 and steel.

I have plenty of time; this is retirement project that happens to have large potential commercial pay-off if successful. I have always been blessed with the ability to learn; I went from a USAF trained electronics technician to designer of patented UWB ADC and DAC architectures and advanced multi-mode radars for DARPA, ONR, etc. For this project, I've had to learn thermodynamics and mechanical design and, though I'm certainly no expert yet, my consultant who *is* an expert has said my work is "surprisingly good."

I'm not contemplating doing this work myself so I can say I did it myself; I have long experience in developing new designs, and I generally prefer to "own" critical processes. This is because my competence as a designer/inventor is vastly improved by having complete top-to-bottom understanding of the entire process. I had one project in which I assumed someone else would cover a key element that I didn't understand, and it was a nightmare. This is not to say I always did everything myself; I didn't. I had a large team of engineers from every discipline and several manufacturing experts on every project that took my visions to detailed implementation. I understood every detail of what they were doing however. That knowledge is what allowed me to invent solutions that reflected the needs of every discipline and thus went through the whole cycle with very few major disruptions or surprises. I view the machining of a mechanical product intended for production to be too important not have some pretty detailed knowledge under my belt to inform the design. I know gaining that knowledge will be costly in time and money, but the knowledge itself is priceless IMHO. Given a good local machinist willing to educate me as we go along, however, I may be able to gain the knowledge in-process.

I'm having a face-to-face with my son (an ME responsible for precision production/machining)in a week or so to discuss the build plan.

I really appreciate the care and consideration you and others have put into your comments on my engine. It's been invaluable. I know it sometimes sounds like I'm ignoring people's advice, but I assure you I am not. I absorb it and think about it over time and often come back to what was suggested.

Rod

 

[enginesrus]

In the old days experience was king in a machine shop. Nowadays all it takes is being computer savvy and knowing a few basics of machining. I know well, I was lucky to get in on the very last of the major manual type machining, there was no cnc then only some tape controlled machines, I have worked with some people that have next to zero experience if the aptitude is there they can catch on very quickly in months. And yes you need a good quality solid machine, that is capable of close tolerance work. Haas is not my first choice but there are a lot of outfits that use them.
Why you don't want to farm out work is because you have little control who see's any proprietary information, yes there are forms that can be signed and or what ever, but still, I wouldn't trust it. If you do your proto typing in house you can hire a machinist if that is what you really need, then its only a small amount of eye's on your info.

 

[SwinnyGG]

Hey, if you've got the time...

And it sounds like you do.

Best of luck.

Just make sure your budgeting accounts for tooling, and GOOD tooling. Cheap tooling will slow down your ability to learn, and make it harder to produce good parts.

 

[RodRico]

enginesrus,

I chuckled a bit over your concerns about protecting my intellectual property... Given the number of "new" engine designs promising great things floating around on the internet, I'm not sure how anyone would decide *which* design to steal! Seriously though, you're right, I do need to think about IP protection.

jgKRI,

I'm not going to make a move on equipment until I know more about what I need. I'm wondering whether there is a machinist in my local area that would be willing to consult and perhaps even supervise my work. Given the shortage of good machinists, it's unlikely, but it can't hurt to look!

Rod

 

[enginesrus]

I would like to know more about the IP as well. I would think since you posted "YOUR" idea here and maybe elsewhere too, that would be proof that it is your idea. I have never posted any ideas I have, all I have to do is wait some years and then someone else comes up with it. I wish I knew how to protect my ideas? I have no way to prove it but as a young kid I thought up many inventions we have now and no recognition for them of course. I guess that is why I'm a grumpy old guy now. (laugh).

 

[RodRico]

enginesrus,

IP protection is one area where I may be able to help you rather than visa versa.

Under old patent law, the "first to invent" (as proven by publication, notebooks, etc.) was granted ownership. The new system is "first to file," and to be eligible for a patent, the idea must be possible, useful, non-obvious to those skilled in the art, and previously undisclosed (no publication of any sort, sales of products incorporating the idea, etc.). Had I discussed the idea in this forum or published it in the Create The Future Contest *before* I filed my patent, I would be ineligible to do so now.

The new "first to file" system would appear to limit innovation by small inventors by requiring costly legal action before the idea can even be discussed with machine shops, consultants, potential investors, etc. This is not the case. An individual can self-file a Provisional Patent at very low cost on-line. The Provisional Patent is not evaluated by examiners and will not result in a patent being awarded, but it does provide protection against theft for one year. This time is intended to allow development of the idea to determine feasibility, shop for investors, etc. before committing to a full patent. The full patent can also be done without attorneys on-line, but few take that path, and attorneys are expensive (I got a "deal" at $5,000 for the US filing and $3,000 for the filing under the Patent Cooperation Treaty).

Patents are written to be as broad as possible and don't generally address any specific implementation (read the "claims" section of any patent on-line and you'll be surprised how broad they are). Everything I have publicly disclosed thus far is well within the bounds of the patent I filed last year. There are a few additional refinements I have developed in the time since filing, but I don't discuss those and will not do so until I either write a new patent referencing the old and adding the new refinements or decide the new refinements are not significant enough to justify the cost. I won't make this decision until I have a working prototype because I want to have all or most of the refinements in place before incurring the expense of another patent.

Any idea you've had in the past may still be valid. If you feel your idea may be commercially viable, do a detailed patent search to confirm it hasn't already been patented. You can do this on-line. Make sure you understand patent classification codes (both US and international) and use them in your search.

Rod

 

[enginesrus]

Of course my ideas of the past are patented. I just wish as a kid I could have had the recognition. For example one of my ideas had to be about 1959 or 60, it was the cell phone. I even figured it either needed repeaters or satellites to work.
But no way to ever prove that even if my mom was still alive.

 

[RodRico]

enginesrus, Bummer. You'd be a gazillionaire!

 

[waross]

The spread frequency spectrum technology was patented by Hedy Lamar in 1941.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[enginesrus]

Okay so that is related to lots of different electronic devices not just a cell phone. The main thing about a cell phone is the small carry along phone, and the towers or repeaters that are needed to capture the weak signal and relay it.
I guess this does not belong in an engine forum.