Aeromomentum engines

[racaldwell]

Hi Tim,

Maybe Larry will part out the Aeromomentum engine. But maybe not, I could ask him next time I see him. He put the Xenos on Barnstormers but no interest. He wants to sell the Xenos but knows the odds are zero. Probably another hangar queen. I'm trying to be nice but it just slipped out.

Rick Caldwell
Xenos 0057

[Matt541]

Keep us updated on your Aeromomentum journey Tim, very interested in this engine option. Who knows...

[n307tw]

Thanks guys. I’m very excited to move into this direction. Rick, please ask if he is willing to sell his engine I may be interested in buying from him. Thanks!

-Tim


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[lakespookie]

Its a very interesting power plant option but the single point failures are a bit of a concern.

[n307tw]

I’d be interested to hear more on what you mean. I’m open for all information. Thanks!


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[WesRagle]

HI TIm,

lakespookie is probably referring to the lack of a backup ECU. If the ECU fails there is no secondary source of fuel or ignition. And of course the engine is fully electrically dependent.

The most informative video on the engine I have found is here: https://www.youtube.com/watch?v=leQWYeHkNbw. Approximately 22 minutes into the video Mark talks about the "claimed" reliability of the ECU stating that it's probability of failure is less than the probability of two magnetos failing simultaneously.

Wes

[SP1]

I'll add some thoughts. I've considered this engine for quite some time and have gathered some information, I know there are probably about 5 others looking at this engine. Some facts I've gathered:

Pricing- probably the first thing that catached your eye regarding the AM15. This is some of the costing I've put together (let me know if I'm missing anything)
Aeromomentum
Engine 12495
Exhaust kit 1294
Fuel kit 733
Cooling kit 937
Mount 1300
TOTAL 16759

Jabiru
Engine 18990
Aeroinjector 410
Mount 1579
Air filter 60
Oil separator 130
Baffle kit 250
TOTAL 21419

Weight
Aeromomentum provides a weight comparison on their site http://www.aeromomentum.com/am15.html, but this lists only the engine weight, not FWF total, which could vary. Some others on the site suggest that the Jabiru installation is above 200lbs (maybe up to 220?). There was a post on the Zenith Forums that showed an AM15 FWF total weight of ~241lb http://www.zenith.aero/forum/topics/aeromomentum-am15-video. I read somewhere else that the weight was reduced by 20 lbs. Regardless, this exceeds the 200 lbs FWF recommmendation by Sonex. The Corvair with FWF comes in closer to 245, as a point of reference http://sonexbuilders.net/viewtopic.php?f=9&t=4273&p=32930&hilit=cleanex+fwf+weight#p32930. Dale Williams has an writeup that reasons why a higher weight is okay. From my understanding, the front CG limit (which the FWF weight influences) is often determined by elevator authority. Moving some weight to the back could be one way of staying within the limit with a heavier FWF.

[GraemeSmith]

Talking of single points of failure. There are certificated Lycomings out there with "traditional" manual dual mags - driven by a single central gear. When that gear fails - you lose both mags. In some ways it is worse than Aeromomentum's issue because so few pilots are aware of the Lycoming shortcoming.

[lakespookie]

Graeme Hit it right on the head with the electrical dependence and the single Ignition system. Granted other powerplant options in our aircraft all have their own issues. I am sort of on the fence personally as far as engine options the AM15 is tempting especially in the higher power configurations. Although the base engine is pretty comparable to the Jabiru except 4 instead of 6 cyclinder. Most studies i have read pretty much say a 4 with a dead cylinder is a pretty big loss of power in comparison to the loss of a cyclinder in a 6 cylinder engine.

The Other concern is that the ECU uses an O2 sensor and they tend to not play well with leaded fuels if you are not planning on going to other airports its not a concern but if you are going to be running leaded fuels that is def a consideration.

UL engines are exhobrantly priced and have the same electrical dependence concern.

And the VW's need a better charging system although i am interested in hearing from someone who has a turbo aerovee and how the performance scales with altitude given a turbo systems ability to normalize or make up for air density in comparison to a non turbo engine. That being said i assume they are cooling limited at some point and depending on the compressor and turbine selection might not be able to normalize at higher altitudes. Additionally, the early breaking/seasoning issues with those turbos is a huge concern from a safety of flight side of it.

The Corvair is another interesting option that is also not factory supported.

Like most things in aviation everything is a trade off and everyone has to make their own decisions on the level of risk and risk tolerance they are willing to assume and i will def be looking at your build in anticipation the 65 amp alternator is a huge bonus and a larger battery in the rear can make up for some of the W&B and electical concerns assuming you are not messing with instrumentation hell i have seen a really slick aux fuel tank in the rear that would pair well to aleviate the W&B questions.

Sorry to sort of go on a tangent i tend to do that but looking forward to your build updates.

[sonex892.]

Talking of single points of failure. There are certificated Lycomings out there with "traditional" manual dual mags - driven by a single central gear. When that gear fails - you lose both mags. In some ways it is worse than Aeromomentum's issue because so few pilots are aware of the Lycoming shortcoming.

Jabiru is the same in this regard. Both rotor / distributor gears are driven off a common gear. I know of one instance where failure of this gear caused a complete engine failure.
Steve
Sonex 892