O-100-- interesting new engine

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sotaro

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As I recall from the video of 2017, the cam was stock and the intake and exhaust was not. This has been an interesting discussion and I appreciate all contributions. Being a naysayer is always difficult in such a small group, even if online, so I thank those with doubts for putting forth their opinions. Now, does any one want to make any friendly wagers with proceeds to charity?
 

hangarrat101

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Just seeing everyone talking about power, this is a reply Pete posted to this very question some time ago.

OK, time to chime in here. First of all, YES, it IS running Jan Carlsson. I first ran the prototype on April 16th, 2014, then many times for the crowd at AirVenture 2014 and now hundreds of times for initial testing. The videos on the website should show that.

About the expected power. I agree that the O-200 is less than 100 hp. Continental themselves rate it at 98HP @ 2750. I wrote about my estimations of power a while back on this thread but, before I review that info, let me say that my test stand is undergoing a mod as we speak that will give real-time torque values on the instrument panel thereby eliminating all the guessing. I will post video of that when I get it finished. So Jan, the way I calculated it initially was to compare the factory reported HP/RPM ratings for the following engines: A-65, O-200, O-235, O-320, O-360. O-540. By backing those numbers through the torque formula, T= 5252HP/N and dividing T by the displacement I found that the values ran between .87 and 1.2 ft.lbs/cu.in. The biggest factor on raising the value seems to be the compression ratio; i.e. The higher the compression ration the more ft.lbs./cu.in. the engines had. By plotting these known values against their respective compression ratios, I found that engines with 9:1 compression have values of approximately 1.05 ft.lbs./cu.in. So in estimating what we might see for HP on the O-100: 105 x 2900/5252= 57.9 HP. I would not be surprised to find that the engine, as it sits, is only making 50HP right now but ONLY because I know I don't have an ideal carb and mixture. The Marvel-Schebler MA-2 is VASTLY better than the Zenith but the engine is still running rich.

Let's all reserve the HP opinions until the dyno gives me some accurate torque readings (that goes for me too). I'll put N/A on the website until I get the dyno built. Jan, I agree with you that fuel injection/electronic ignition might help a ton in the future but my main focus right now is to get the production kits up and running in beta testing and find a readily available aircraft carburetor that will work well. I would be surprised if we can't get it up to 58-60 horse with a little tweaking and continued R&D on this otherwise mechanically sound platform. Thank you for your input.
 

mm4440

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Cams & magnetos on aircraft engines are from the dark ages. The missing hp can be found there and running at a higher rpm like in F-1, Ul-Power, VW, Jabaru. etc. A crank triggered efi/ignition, flywheel dynamo/ring gear and front mounted starter would simplify, clean up the back end of the engine. Vibration and sound make the difference between a sweet running and a merely acceptable power plant. Pete's O-100 is a sweet runner. More power can be found if needed.
 

Victor Bravo

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Just got an update directly from Pete Plumb:

The new rear accessory case pre-production prototype has arrived and been test fit, it's gorgeous, and fits the main crankcase perfectly. First ten production rear cases have been ordered with no changes.

First ten production crankshafts are scheduled to arrive in August. These are FORGED 4340 steel, the exact same material and process as the legacy Continental and Lycoming engines with tens of millions of flight hours in fleet service for 70+ years. Considering that these cranks are a lot shorter in length than 4 cylinder cranks, and balanced better, there is high probability that these will be every bit as reliable (or more so) in long term use than the longer, "twisty-er" 4 cylinder cranks.

This freezes the design and moves it from pre-production prototype design/testing to the full production engine. All of the parts that are either in hand now or on order are production parts that can be used in production kits.

Photos are forthcoming and will be posted here as soon as I receive them.

There was no "problem" with the ADI crankshafts. It is a valid and proven material. The problem was that there were no US shops that would do all of the operations to deliver a finished crankshaft. It would have to have been cast in one place, austempered in another place, machined and ground in another place. A logistical nightmare, high FUBAR potential, lots of extra steps, and more expensive after all the shipping. So Pete made yet another decision to do what is best for the customer, and find an American source for a quality forged component at a good price.

I asked about the engine's power claim, on behalf of this forum. Pete has calculated 57-58HP, and the flight testing supports this:

When you cut an O-200 in half, you reduce the cylinder friction by half, reduce the oil galley lengths and pumping requirements significantly, remove some main bearings and cam bearings, and reduce the loads on the gears and cam lobes and valve train significantly. And the windage loss, and the mass oil flow/return.

The A-65 Continental, at 6.3 compression ratio, makes .86 foot-pounds of torque per cubic inch. The O-200 at 7 to 1 makes .92 foot pounds per cubic inch. The Pegasus O-100 at 9 to 1 compression ratio makes 1.05 foot pounds per cubic inch.

At a 14-1 air-fuel ratio, 50+ hours of flight testing and many more hours of ground testing verified an average of 2.66 to 2.7 gallons an hour fuel burn at 2750 RPM, or 75% power (verified using manifold pressure readings).

Using standard propeller efficiency estimates, and a 4 - 1 L/D for the open cockpit configuration (no wheel pants, no streamlined wires, open cowl with Cub style "eyebrow" shrouds, exposed mufflers), Pete calculated that at 75% power the engine needed to make 36 horsepower to overcome drag in level cruise flight. This supports a solid estimate of 57-58 gross horsepower for the engine.

So if you want to have a "global reference number" for comparison purposes, this engine makes 57-58HP by the same method of estimation as an O-200 makes 100 HP, which is by the same method of estimation by which the O-320 makes 150 HP, which is by the same estimation method as the Rolls Merlin makes 1600 HP.
 
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dragon2knight

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Wow. I gotta say those parts look great! It sucks he couldn't follow through on the ADI cranks....but it's totally understood why. Sometimes life hands you lemons and he seems to have made some nice lemonade with the 4340 forged ones. Fingers crossed he finally gets this out the door before the end of the year.
 
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PW_Plack

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When you cut an O-200 in half, you reduce the cylinder friction by half...remove some main bearings and cam bearings, and reduce the loads on the gears and cam lobes and valve train significantly. And the windage loss, and the mass oil flow/return.
You simultaneously lose half the gross HP. There's no gain here. It's a wash, or slightly worse.

...this engine makes 57-58HP by the same method of estimation as an O-200 makes 100 HP...
So if the O-200 really only makes 81 HP...

Hopefully there will be dyno numbers or club testing coming at some point.
 

Victor Bravo

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Yes, I believe there will be dyno testing, test clubs, and verifiable data measurements. Pete has always taken the position that there will be valid numerical data gathered and disseminated, especially because the engine will eventually be ASTM approved as an LSA engine. A lot of testing and validation will have to be done for the certification, so measuring actual performance numbers will be easy to do at the same time.

Until that data is available, those of us who have seen the engine fly can only put our own word and our own credibility up as collateral. That is of course no substitute for real data, but if this little engine was not capable of putting out the power necessary for the Cracker Jack 2 to take off with authority, it would have showed up on the videos. The videos show the aircraft not wasting any time getting off the ground, on a warm day, with a 6 foot 2 pilot aboard, and a weight far in excess of Part 103.

As the pilot of the camera aircraft (1956 C-172 with starboard door removed) on the day of the Cracker Jack inflight video , I can say that the Cracker Jack with the O-100 was easily able to maneuver and hold formation at speeds between 60 and 80 MPH. At least one well known HBA forum member was there on that day as well, and I believe that person would agree that the O-100 engine provided very reasonable and sufficient power for that aircraft. And that was with a less than optimized carburetor and intake system compared to the production version.
 

Topaz

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... At least one [other] HBA forum member was there on that day as well, and I believe that person would agree that the O-100 engine provided very reasonable and sufficient power for that aircraft. And that was with a less than optimized carburetor and intake system compared to the production version.
That person was me, and yes, the airplane did not at all behave as if it were underpowered. The CrackerJack is an all-wood-frame-and-fabric LSA-type single-seater. I don't know the weights either, but it's no ultralight by any means. I've seen airplanes in the same overall weight class fly with 4-cyl VW engines in the 60-65hp power class quite a few times, and the CrackerJack with the pre-production O-100 seemed, if anything, more "sprightly" than those airplanes. Climb-out was steady and strong, even on a rather warm day. I'm sure the fact that it turns a larger prop, more slowly, than those VW conversions has much to do with the performance.
 
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