915is Updates in the Kitfox?

[tracstarr]

I've been keeping my eye on the 915is - but I've not seen a lot of info out there at all. I came across this from a few weeks ago today https://youtu.be/Q2oyGg4s3EU

I remember reading here somewhere that it was mentioned a possible concern with the prob on the 915is in the kitfox. Something about hydraulics? I could be wrong.

Anyway, in this video they mention a constant speed prop that's computer controlled and doesn't require anything extra. At least that was my take. About 40 lbs heavier than the 912is.

I know it's probably all guessing right now - but do those that know more about engines and kitfox in general think we'll see this within the year? Or do you know of or think there are bigger things to overcome?

[Danzer1]

Well Keith - CPS (Califironia Power Systems now has it priced at $38,667 and it has been constantly going up prior to even one unit being delivered. Their Q&A also states the current version is only set up for variable (constant speed) prop. And they state maybe another year for a fixed pitch version.

Pretty rich for the HP in my view!

[tracstarr]

Ouch. That is up there in cost. I also noticed the main product page shows TBO at 1200 hrs, not 2000. That's a big difference.

[Av8r3400]

IMO - Not even close to worth that kind of money.

[aviator79]

The latest I heard was that a hydraulic Constant Speed Prop was required. I wonder if they'll extend the TBO after it acquires some service history. As it is, if you make an apples-to-apples comparison by assuming ~$10/hour in overhaul costs for the 800 hours you're losing, The cost compared to the rest of the rotax line is a staggering $46,667. I was hoping there would be a way to justify this engine on my plane, but it's looking bleak.

[WWhunter]

Since I am in the market for a new flivver I am also weighing the different options. Edge Performance seems to be a better option if one wants power with light weight. It is an expensive engine also,and warranty might be something a buyer would have to consider.

Although a lot heavier, the Titan has more power, and $10K +/- less. Unfortunately it needs Avgas if that is an issue. You can get a car gas compatible motor with less HP though.

[Esser]

ULPower? Still surprised No One Has popped one in. I was going to until I got a deal on my engine. It’s lighter, costs the same as the titan I believe, and runs on auto fuel. The 130hp model would be waaay cheaper than the 915 and the titan. Looks like zenith is having good success with them

[colospace]

When I last visited the factory some years back, there was a customer plane in the shop getting at least a partial FWF developed for its UL Power engine.

[WWhunter]

Agreed..the UL is another option. For some reason there just doesn't seem to be many out there. I looked at them also and they are a very nicely built engine. Cost per Hp is very similar when compared equally. I know there were a few RANS aircraft with them installed but I never saw or heard much more about those either.

[avidflyer]

Same issue as the Jabiru in a way I think. Direct drive/high revs, small prop. Not the best combination for a STOL type aircraft. JImChuk

[jdmcbean]

Rotax just had a price increase...
912UL $16,503
912ULS $19,701
912iS $23,284
914UL $31,539
915iS $38,667

Have talked with Edge Performance about there engine.. and we can supply them a new engine that they can modify.. to the EP912STi engine currently listed at 28000 Euro ($33375 US) I do not know if that reflects the current Rotax pricing.

As for the 915iS.. We are (have been) working on a firewall forward package. It is a little more complicated and has larger oil cooling requirements and absolutely requires an inter-cooler. Exhaust and Turbo are larger as well.
If all goes well we hope to be flying it soon.

[tracstarr]

Thanks for the update!

[av8rps]

ULPower? Still surprised No One Has popped one in. I was going to until I got a deal on my engine. It’s lighter, costs the same as the titan I believe, and runs on auto fuel. The 130hp model would be waaay cheaper than the 915 and the titan. Looks like zenith is having good success with them

On the Highlander "wings forum" you can read about the struggles a builder went through installing and operating a UL 130 hp engine by searching for UL350. He eventually got it to work good, and out of fairness, in many regards it had some great attributes (simple, nice "aircraft type" sound, etc). But if you read all of "Stede52's posts on it, as my memory serves me, after he sold it he admits he wouldn't do the UL engine again. He admits a zippered/modified 912 will outperform it, be lighter, and burn less fuel. And as much as I hate to say it, those are common shortcomings when comparing against a 912, as to be truly effective it needs a PSRU as it turns higher rpm than a standard aircraft engine. So prop efficiency is just not in the same league as the 912.

Fwiw, the 6 cylinder 130 hp Jabiru has similar performance. Non geared high revving engines just don't work well on STOL type aircraft. They will however work reasonably well on faster planes that typically use shorter props. But so will a 912.

With all that said, I'll be surprised if the 915 doesn't provide outstanding performance. I agree it is a bit pricey, but I personally think it will get the job done that most other engines won't. Time will tell...

[Clark in AZ]

Rotax just had a price increase...
912UL $16,503
912ULS $19,701
912iS $23,284
914UL $31,539
915iS $38,667

Have talked with Edge Performance about there engine.. and we can supply them a new engine that they can modify.. to the EP912STi engine currently listed at 28000 Euro ($33375 US) I do not know if that reflects the current Rotax pricing.

As for the 915iS.. We are (have been) working on a firewall forward package. It is a little more complicated and has larger oil cooling requirements and absolutely requires an inter-cooler. Exhaust and Turbo are larger as well.
If all goes well we hope to be flying it soon.

Hey John,

Does the 915 use the same cowl as the 914 or will it require a "special" cowl?

Thanks,
Clark

[jdmcbean]

The 915 will be a complete firewall forward..
Same basic cowlings with mods... but most likely different oil cooler, radiator and requires an inter-cooler...
While you would think the wiring would be the same as the 912iS.. Rotax decided made changes to that as well...

[Flienlow]

It could be worse, a new IO 540 is $73,000. if you can even remotely wrap your head around that.

But at what point does the pricing prove to simply be false economy? Or is this an aircraft engine and you just suck it up?

[av8rps]

I heard from a friend a few years ago that tbe turbo 540 was over 100k.

[jdmcbean]

The Lycoming 233 and 235 new are over $35K and the New O-200D was about $34K.

[AeroBuilders]

I love the thought of the new 915is in the Kitfox STi.

More 915is news...

https://www.avweb.com/avwebflash/news/Sport-Expo-Rotax-915-iS-Soon-Ready-for-Rollout-230216-1.html

[SomeDay7]

Any body know what kind of prop setup you might want to run with this engine. Pitch, length and type? Just fantasizing I guess. Jim

[Esser]

It would almost be pointless to have this engine without a constant speed prop. Rumour has it that it has to be hydraulic so that rules out airmaster and pretty much only leaves GT/MT propellers

[SomeDay7]

Just wondering if the prop and hub would come straight from rotax or other combinations would work since it is automatic with the 915is

[Av8r3400]

I'd like to know whose hydraulic constant speed prop falls into the the MMOI requirements laid out by Rotax for the gearbox. Or did they strengthen the gearbox to handle a higher inertia?

[Ronin]

I believe the Whirlwind CS meets it.

[jabkwab]

MT makes hydraulic propellers for Rotax engines, installed on Diamond da-20 aircraft.

https://www.mt-propeller.com/en/entw/pro_hydr.htm

[jdmcbean]

Here is a quick update on the 915is
As many of you have figured out we are working on the firewall forward package for the 915iS. We have 1 of 3 915iS prototype engines available and have been working on a mock-up airframe to determine many things. We were concerned we would need completely new cowlings and possibly a completely different setup. Rotax made some changes from the 912iS that complicated the install. The Turbo is larger, the exhaust is much larger, a larger oil cooler and unlike the 914, the 915 REQUIRES an intercooler. We have been able to make some small changes for most the install and needed to make a custom intercooler and ducting to the intercooler. The firewall forward is also going to need Teflon hoses due to the tight routing.
Currently the engine requires a hydraulic constant speed prop. The only one available is MT.. that will change fairly quickly as there are others working on props now. The single lever control is a topic for another post.
We are now removing the Titan from the STi in preparation for the 915. If all goes well we should have an engine run close to the end of the month.
The Titan has been a solid engine with great performance and I would not hesitate to use this engine as the Lycoming/Continental alternative engine for the Kitfox.
The complete Titan firewall forward and engine are now available if anyone is interested. Contact us directly for pricing.
We’re looking forward to flying the 915!

More details to come...

[Av8r3400]

Kool stuff happening at the factory!

It will be very interesting to see the real performance difference and the final weight numbers between the Titan and the 915 on the same airframe!

[Bud Davidson]

I am favorably impressed with the advancements made by Kitfox and their contribution to furthering flying for fun. Some time ago the factory assured me they support earlier Kitfox models. Great!!
I get concerned when i read about all these advancements, particularly those that move the Kitfox from the aircraft category with low gross weights and non-complex controls so necessary for attracting pilots wanting to fly for fun using their drivers license instead of an FAA medical. I am a private licensed pilot since 1959 but today fly on my drivers license. The model IV is perfect for me today. I hope these models with fixed pitch props will always be available. Otherwise, the Kitfox will progress itself right out the aircraft category it pioneered so successfully.
I am for progress, but would hate to see the loss of this basic "first" airplane.
Kitfox, please continue to develop and provide your basic airplane.

[jdmcbean]

Bud,
No threat.. We keep our eye keenly on the future but stay firmly in touch with our past. The Kitfox simply shows how well it does in both environments. :)


I am favorably impressed with the advancements made by Kitfox and their contribution to furthering flying for fun. Some time ago the factory assured me they support earlier Kitfox models. Great!!

I am for progress, but would hate to see the loss of this basic "first" airplane.
Kitfox, please continue to develop and provide your basic airplane.

[jdmcbean]

Now for the single lever control..
This is an interesting subject. It is NOT being proposed in the ASTM or even through the FAA.. it is being talked about and politically pushed in certain circles. No light in sight that I have seen. We can all agree that the CS props should be allowed with the Light Sport and hopefully someday the FAA will catch up to the future.
The single lever is not Rotax.. It is actually a governor that is electronically controlled (instead of cable controlled). The only Engine Management Unit (EMU) that controls the governor currently is the Stock Flight Systems EMU for the 912iS and 915iS. Rotax, MT and Stock work closely on this program.
Yes the prop can still be cable controlled as any Hydraulic CS prop.
I'm sure there will be more developments regarding the single lever.. for the 915iS it is currently an MT prop, Electronic Governor and the Stock Flight Systems EMU. I suspect AirMaster will have a prop and I know there is another that may be available in the Fall. Hopefully Garmin, Dynon, GRT, MGL will come on board with the software to control the electronic governor.
I should mention the the 915 can be operated with a fixed pitch but one would not be able to take advantage of the full potential of the engine.

[Shadowrider]

John any updates on the 915? Do you have it flying yet?

[brandonschmit]

Now for the single lever control..
This is an interesting subject. It is NOT being proposed in the ASTM or even through the FAA.. it is being talked about and politically pushed in certain circles. No light in sight that I have seen. We can all agree that the CS props should be allowed with the Light Sport and hopefully someday the FAA will catch up to the future.
The single lever is not Rotax.. It is actually a governor that is electronically controlled (instead of cable controlled). The only Engine Management Unit (EMU) that controls the governor currently is the Stock Flight Systems EMU for the 912iS and 915iS. Rotax, MT and Stock work closely on this program.
Yes the prop can still be cable controlled as any Hydraulic CS prop.
I'm sure there will be more developments regarding the single lever.. for the 915iS it is currently an MT prop, Electronic Governor and the Stock Flight Systems EMU. I suspect AirMaster will have a prop and I know there is another that may be available in the Fall. Hopefully Garmin, Dynon, GRT, MGL will come on board with the software to control the electronic governor.
I should mention the the 915 can be operated with a fixed pitch but one would not be able to take advantage of the full potential of the engine.

May I ask a newb question? I see that the 915 has the same exact bore and stroke on its pistons as the 912/914 engines. Does this mean the only way the new 915 is making more HP is that it's going to higher RPM's versus the 912/914? Hence your statement that a fixed pitch prop wouldn't take advantage of the engine's HP because it's essentially the same engine and has roughly the same HP/torque curves at the lower RPM's as the 912/914? The only way to take advantage of the higher horsepower at higher RPM's is to keep the engine spinning at the high RPM's and adjust the pitch of the prop for max thrust during takeoff and max forward speed at cruise? I did read an article on the SeaReys that said cruise RPM was 4800? So that actually seems lower than normal cruise RPM? If it's making more power due to higher boost/more oxygen in the fuel/air mixture, then why isn't a fixed blade prop going to work if the RPM range is the same? That's where I'm getting confused. Is it due to the changed reduction unit? Why would they change that if so?

Thanks,

Brandon

[Esser]

The constant speed prop keeps the rpm the same. It’s the manifold pressure that is showing how much power the engine is making. Similar to if you were biking turning the pedals at 120rpm. If you went up a slope you could still keep 120rpm but you would have way more force on the pedals to do that.

[jiott]

I don't believe the 915is runs at any higher RPM than the 912/914. The extra power comes from the turbo boost (packs in more air/oxygen to burn more fuel) AND the intercooler which cools the hot boosted air so even more dense air can be packed into the cylinders.