UL-Power UL350iS Engine

[SportyPilot]

So I see that Kitfox is now offering FWF package for the ULPower UL350iS engine. I'm wondering if this same FWF package can be used for the UL260iS. I ask because I'm concerned that the ULPower Ul350iS will take the aircraft outside of the LSA limitation.

[Esser]

The 260 and the 350 have the same mount and are within 12 lbs of weight so I would assume they are interchangeable. However, I am guessing you are worried about breaking the speed rules. Worst case you can pitch the prop so you don't break 120kt. Also you can use the UL350i which the same engine with lower compression pistons so that you can use a lower octane fuel. It is 118hp.

Another simply fix is a mechanical stop on your throttle cable.

[Danzer1]

And then again - it may not take you out of LSA! Check the power curve on their site. The 130 hp is at 3300 rpm at SL! Who in their right mind would run a direct drive at 3300 rpm? Realistically, it would be more in the 80 to 90 hp useable range. Fuel flow seems a little high for an injected engine too. Personally, I'd be apt to wait and see some real world data from an actual installation in an aircraft. I haven't heard of any yet. I'm in wait and see mode!

Greg

[RobS]

You may have already seen/heard this, but the UL350 has been installed on at least one Highlander and discussed for quite some time in that forum. Nineteen pages of comments - and I have to believe you'd find a lot of good information there.

http://wingsforum.com/viewtopic.php?f=218&t=18388&hilit=stede

[Esser]

Hey Greg,

The power curve is pretty flat. Makes 120 HP at 2700RPM

http://www.ulpower.com/engines/ul350iS/performance.html

Steve Dentz operates his highlander as an LSA with a 350iS. He says it out performs his Rotax ULS powered Highlander in every aspect.

[Danzer1]

Don't want to hijack the thread and I'm not suggesting this engine is a poor choice. I'm suggesting that each builder look at realistic performance numbers for their intended mission. That 120 hp is at SL (close to ISA rating as stated).

No one (I know of) "flies" at sea level. The chart below that one referenced, shows density altitude figures. Which is a much more realistic method of determining what power you really might have, in the conditions you fly most. I fly out of Denver (high and hot), so it's always on our minds here.

FWIW, the Zenith CH 750 Cruzer prototype is powered by one too - http://www.zenithair.com/stolch750/index-cruzer.html

[N714SM]

Scott Ehni put a new UL-350iS on a dyno. According to Scott it produced "115 corrected SAE HP." He went on to state that since the engine was new [not broken in] he expected it to eventually produce its rated HP (130).

I didn't see where the geographical location of the test but if it was done at his shop it would have been 233 feet MSL, but "corrected" SAE HP would have considered altitude . . .

[Danzer1]

G-man, It sounds like you are agreeing with my post but I'm not sure with the...... added:o The correction would then be to sea level discounting altitude or more importantly density altitude where one actually flies.

Don't get me wrong, I love baseline numbers and charts, it is the only thing that gives us a good starting point as to what might work for us and what probably won't. I actually commend UL for publishing the charts, very many manufacturers don't and won't. That's why we end up relying on others experiences. The problem with that approach is, there are way to many variables that confuse "what might work for me".

Baseline numbers (dyno'd) are great as long as one remembers: they are at SL (usually, unless noted otherwise), they are engine only ie; crankshaft (no prop driven), they are not moving anything around (static) nothing driven like a weighty and draggy airplane in less than perfect air - they are just what they say they are - baseline.

The dyno info is somewhat useful because it holds that the UL charts are likely pretty close (good thing). But, what still concerns me; everyone looks at rated (baseline) HP. Torque is all that matters and it is directly related to HP at a given (usable) RPM. However this engines "rated" HP of 130 is at a (mostly) unusable 3300 rpm. I don't know of any propeller manufacturer that will allow continuous operation at that speed (this is a direct drive motor). The only one that comes close (that I'm aware of) is Whirlwind and that is for 5 minutes. max. - not continuous. Not to mention the fuel consumption at 3300 rpm is over 9 gallon/Hr!

So, at a realistic rpm of say 2400 rpm, this engine is 108 hp, and 236 ft lb of torque. Still pretty darn good - except in extrapolating the UL fuel consumption chart - that equates to over 7 gallons per hour!

So lets drop that down to 2100 rpm which shows 94 HP which equals 235 ft lbs of torque. Still pretty good and as Esser says - it's a pretty flat curve. But now look at the fuel consumption chart Linked here for reference: http://www.ulpower.com/engines/ul350iS/fuel-consumption.html

It only shows 80 hp at 2100 rpm which would equal only 200ft lb of torque at a fuel burn of 5.3 gallons /Hr. So one has to wonder: does it only produce 80 HP at 2100 rpm per the fuel chart or does it really produce 94 HP per the HP chart? If it does, what is the fuel burn at 94 HP and 2100 rpm? Just food for thought!

In any case, per my original post, this engine may not take you out of LSA, may or may not be appropriate for your mission and by all means please take into account the probable density altitude where you fly. You may find you want or need more usable HP (torque) than you initially think.

Blue side up (unless you're on floats)!
Greg

[Esser]

If you look at the fuel consumption of a 912ULS at 100HP it is 7gph so I think the UL350iS at 7GPH at 108HP is pretty good.

Those fuel charts are kind of a crap shoot though. Lots of variable but thanks for pointing that stuff out.

[Danzer1]

Esser,

I'm not looking to get into an argument here, and for the record I'm not a fan of either engine - the Rotax ULS or UL 350.

But, I don't see where you came up with 7 gpm (26.5 l/hr) for the UL 350 at 108 hp and 2400 rpm? The fuel flow data for 2400 rpm stops short of 108 HP. Even at 100 HP (extent shown on the fuel chart), it shows 27.2 l/hr or 7.2 g/hr. Through interpolation, the fuel flow at 108 HP only shows in the 2700 rpm range at approx. 30 l/hr or almost 8 g/hr. 8 percent more hp for 14% more fuel burn?

If I were a fan of the UL350, I'd be looking at the HP/Torque chart as relates to the corresponding fuel burn - all of those HP/Torque numbers are past the end of the rpm range tested on the fuel burn charts! How could that be?

In considering any engine, I wouldn't be looking at maximum rated HP anyway - it's useless and always outside of a normal operating parameter. What gives you the best indication of usable power (torque), is the maximum torque available for an engine at a given (usable) rpm (at the propeller). And then compare that, apples to apples.

Blue side up,
Greg