ULPower

[rv6ejguy]

Originally Posted by KatieB

What I meant was, what happens when electrical power is killed to the aircraft. Say you have to shut off the master due to smoke in the cockpit, for example. Will it keep running as if it had mags/carb? Looks like it will if you use their special buffer capacitor, since the ECU is wired to the regulator/rectifier and alternator.

It's a single-alternator, single-battery system, according to the UL Power website. If you have an alternator failure, it will run until the battery dies, about an hour on the battery they tested. If the battery dies first, it runs "as long as necessary" on alternator power... or until the alternator burns out. That's fine for a VFR airplane, but if you're putting one of these in an RV intended for IFR, is that battery or alternator going to last until you're in a position to land? These engines were modeled after Jabiru engines. The alternators are basically motorcycle stators. The drawing on the UL site is identical to a Jabiru system with the stator and rectifier/regulator. I've seen them fail quite a bit. They burn out, regulators go bad. Maybe UL has improved them? People need to be prepared, is all I'm saying. I don't have a dog in the engine fight anymore, thank God. In fact, my old friend/colleague sells both Jabiru engines and UL Power. Those ULs do look sexy. But I cringe when people get all starry-eyed over the new technology and assume that it won't fail. I'd want a dual-alternator, dual-battery setup on one of these, personally. It would help offset the weight difference, too...

I agree, you are totally correct that these engines (and any other ED engine) should have a backup power source whether that be another battery, alternator or both.

Most often we wire the backup power so the engine can continue to run with the master contactor open though there are many ideas on how to accomplish backup power and not all follow this concept.

[Canadian_JOY]

It's rare that I can do much other than read these threads and absorb information. Perhaps that's changing...

I'm peripherally involved in an aircraft equipped with a Rotax 912 iS engine. Rotax appears to have given much thought to the topic of redundancy in an electrically dependent aircraft.

The iS engine has two engine management systems called Lane A and Lane B. It has two alternators, A and B, either of which can power the EMSs. It's a well-designed system from what I can see. What I find interesting is there is also an opportunity to provide a third source of power to the EMSs from the ships battery, thus giving triple redundancy.

The only aspect of this implementation that causes me a little consternation is that some engine indications are not available to the pilot when operating on just one of the two EMSs. Seems a tolerable situation when one considers the EMS will keep the engine running.

In speaking with a certified Rotax iS engine tech I learned that Rotax has plumbed the engine with far more sensors than it currently uses to manage the engine, sensors like knock sensors. Clearly they have built the engine with future development in mind.

Interestingly, the design philosophy of the engine (and the basis of its certification) is that the pilot gets power when (s)he commands it. The EMS will not retard power to protect the engine. This is a fact a pilot is best to keep in mind, both in light of preserving the lifespan of the engine but also in preserving his or her own life when the trees are fast approaching.

[rv6ejguy]

Not everybody has has good experiences with the iS EMS. They had a some issues initially with the system giving uncommanded power reductions in service. I don't hear much about that any more though.

We're working with an iS owner now to remove the factory EMS and replace its eyewatering complexity with SDS.

We've been approached by 2 UL engine owners also to replace their factory EMS' as they were not happy with several aspects of them.

[agent4573]

Originally Posted by rv6ejguy

I don't think their FADEC runs in closed loop. No mention of an O2 sensor on their website.

There isn't a mention of an O2 sensor on the site, but the kitplanes article about the motors says if you lose a sensor they run a richer fuel map. I think your right theres no closed loop control, just different open loop fuel maps based on failed sensor flags.

Originally Posted by Andrew Anunson

Pilots can run a Lycoming LOP (lean of peak) for high efficiency and clean running. That isn't an option with the UL Power engines since the FADEC controls the mixture. So far, Lycoming engines run better fuel burns.

Do you have any source for this? The article I read about the smaller UL engines says they get better fuel efficiency than a similar powered rotax, which in turn are more fuel efficient than lycoming running similar power settings. It would be awesome to have some actual data from all the engines. Also, just because it's fadec controlled doesn't mean you can't tune it LOP off high power settings. Every ECU I've programmed goes way lean in the high RPM/low load area of the map.

[JustPlaneChris]

There are fuel consumption charts on the ulpower website. Choose your engine and there are tabs for performance as well as consumption. Here's the page for the 350iS:

https://ulpower.com/en/engines/ul350/ul350is#4-fuel

Based on what I've seen from Zenith guys who are flying the UL engines, they do not seem to be as fuel efficient as the 912is, nor is there any reported way to run LOP.

[rv6ejguy]

Works our to around .45 lbs./hp/hr. at 100 hp. Nothing impressive for a modern design. A Lycoming can do around .40-.42 with fuel injection running LOP.

[Mike Houston]

Originally Posted by rv6ejguy

Works our to around .45 lbs./hp/hr. at 100 hp. Nothing impressive for a modern design. A Lycoming can do around .40-.42 with fuel injection running LOP.

The problem with the lycoming is it only burns LL100. The ULpower burns Mogas with up to 15% ethanol. In Europe that saves you about $3.50 a gallon.

[rv6ejguy]

Originally Posted by Mike Houston

The problem with the lycoming is it only burns LL100. The ULpower burns Mogas with up to 15% ethanol. In Europe that saves you about $3.50 a gallon.

Lycomings routinely burn 91 Mogas. Lots of folks doing it here on VAF...

[airguy]

Originally Posted by Mike Houston

The problem with the lycoming is it only burns LL100. The ULpower burns Mogas with up to 15% ethanol. In Europe that saves you about $3.50 a gallon.

730 hours so far on a 360 burning Walmart-grade 91 premium with ethanol. Most people don't do it - but that doesn't mean it can't be done.

[Mike Houston]

Originally Posted by airguy

730 hours so far on a 360 burning Walmart-grade 91 premium with ethanol. Most people don't do it - but that doesn't mean it can't be done.

Yes, the 360s have a compression ratio of 8.5:1 which seems to be tolerant to burning mogas. Unfortunately the 390s are all higher though it appears if you are building an RV10 the 540s probably work with mogas as they are all 8.5 :1