hp/lb ratio 20:1

is this not a most elegant powerplant?

http://www.angellabsllc.com/index.html

thoughts, please.

 

Well, no, the problem with it can be described in one word,,,,, leakage...

There are a couple of other issues, but that is the biggest and first one. The "cylinders are slotted on the inside and two "disks" that hold the pistons and form part of the inside of the "cylinder". Combustion products have a leakage path out of the cylinder in between the disks. If you look at the video on the web site you will see a lot of vapor escaping the engine. If there was combustion going on it would be coming out of there just like the vapor that you are seeing condense while they are using it as an air motor.

Second issue is the accelerations required to obtain the oscillating motion that closes and opens the pistons. This will generate really high forces if you are running this really fast.

Also note that if you are running this as a diesel (as they claim), you typically cannot run the engine at high speeds since one of the limiting factors is the speed of combustion. This is why there aren't any 9,000 rpm diesels....

As with many other innovative IC piston engines this one is probably too good to be true too...

 

I just skimmed the site, but I didn't actually see any claims on what this ran on. I see it compared to Diesel Engines, but where does it state it runs on Diesel?

Looks like an interesting design concept, and I can't wait to see what comes of it.

 

If you look on the "Details" page the performance is quoted for a 25:1 compression ratio, which means a diesel.

In a past life I had Preliminary Design for a turbine engine manufacturer, and was responsible for PD of small turbine engines. We kept a "watch list" of internal combustion engines that had the potential to achieve the power to weight ratio (greater than 5:1) of small turbines.

We regularly evaluated lots of IC engine schemes and any engine that made it to the "watch list" had to have the potential to be viable. What we found was that most of the innovative engine approaches generally failed due primarily to excessive leakage and poor combustion sealing. This engine was evaluated when I was there and it never made the list for that reason. We couldn't see how it could effectively be sealed sufficiently to maintain performance.

There are literally hundreds of different approaches to extracting power from enclosed combustion. Most of them fail because they cannot contain combustion gases reliably for any period of time. Other compact engines fail because they cannot extract the waste heat effectively, which puts excessive strain on the engine static structure.

There are several stages of development that most of these engine go through. The first is a design phase where the basic idea is refined. Second is an "air motor" phase where the engine is run as an air motor and this is used to gain investment and fund further research. The next phase is actually running an engine and withstanding the forces of combustion that are generally one or two orders of magnitude higher than that of the air motor. The next phase is where performance meeting the claims is produced, and the final phase is where it is proven that the engine will live a long time.

As you can see, these guys are just in the air motor phase and have a long way to go and frankly I don't see much future for it. There is an update that is dated July of 2009, but it really doesn't say anything about actually running an engine. From what I can see, the concept hasn't had much if any progress due to funding limitations for the last three years.

As I said, leakage from the split cylinders is a huge issue. Moreover, as the speed increases, the piston rings on the outside of the cylinder are going to have increased wall friction due to centrifugal force, while the part of the ring on the inside of the cylinder will lift off the inner wall for the same reason. This alone severely limits the speed that such an engine could achieve without a loss of combustion sealing.

Bottom line is I wouldn't hold my breath waiting for this one to work...