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IO-0390-EXP119 - Accessory Pad

sloengineer

Active Member
Question to the collective: How big of a deal is the lack of back up alternator on the IO-0390-EXP119 for you? I don't necessarily want to start a second battery vs BU alternator debate, but when the rubber meets the road, is it a deal breaker for you? I've had alternator failures and always had a quick out, but it sure would be nice to have that extra alternator.
 
For me, it would be depend on what type of ignition will be installed. If not self powering, I will have hesitations and probably put it in a big concern.
 
Thread moved??

Well I don't know if I'm going to reach my target audience in the Electrical Systems area. I'm trying to see if potential engine buyers are considering the accessory pad as a make or break issue.
 
It's not that difficult to add a backup alternator. I'm not sure exactly what you are asking though.

Per the Van's presser on the new EXP119 engine https://www.vansaircraft.com/2020/07/vans-announces-new-optional-rv-14-engine-configuration/

If you read through the weight loss notations, it says "The accessory housing was optimized for modern glass avionics by removing the unneeded drives for a vacuum pump and tach drive." While I agree a vacuum pump is not necessary for glass panels, many people utilize that pad for a back up alternator.

So my question is for those building a glass panel IFR bird; would loosing the accessory pad be a deal breaker for you?
 
IMHO -- Don't need it...

I am running dual Lightspeed Plasma III ignitions, full Garmin Avionics Suite with dual G3X Touch PFD, MFD, etc.

Electrical power is provided by a SINGLE Hartzell/PlanePower AL12-EI60 alternator, with an Earthx ETX680 providing starting power & runtime ballast. Backup for ignitions and avionics is courtesy of TCW IBBS 6AH and 12AH with notification wired to G3X CAS (Alt Off, Ignition1&2 Off, Battery Fail, Backup Battery Lo, etc.)

I designed the airplanes electrical systems to be fault tolerant, and provide me options. I did NOT design it or intend for it to be indestructible, missions to Mars, etc. If something fails, so be it -- I have data to work with and options which allow for a survivable landing...

Save the weight, carry more fuel.
 
Per the Van's presser on the new EXP119 engine https://www.vansaircraft.com/2020/07/vans-announces-new-optional-rv-14-engine-configuration/

If you read through the weight loss notations, it says "The accessory housing was optimized for modern glass avionics by removing the unneeded drives for a vacuum pump and tach drive." While I agree a vacuum pump is not necessary for glass panels, many people utilize that pad for a back up alternator.

So my question is for those building a glass panel IFR bird; would loosing the accessory pad be a deal breaker for you?

Are you ok with being potentially stuck somewhere if your alternator fails? Right now, I'm ok with it and don't have a back up alternator in my IFR -14A. If my mission changed to doing weeks long trips across the country, I would likely put one on. As far as getting down IFR with a failed alternator, the main battery and my TCW batt back up will give literally hours of time powering the necessary avionics to safely land. The EXP-119 offers more power and less weight but less flexibility to add that back up alternator if it's a must have for you.
 
For me I find it a deal breaker. I have my 2nd EI waiting for me to install it, and then I'll have dual E.I. I installed my standby alternator last fall for 3 reasons. 1 being that I got stranded at approx. 70 hrs with an alternator failure, over 1,000 miles from home. 2 being that I decided that I never wanted to be stuck that badly again. And 3, it gave me the ability to finally get away from magnetos and stick with ignition systems that should require less maintenance.

While I like more power/less weight, the limitations of that particular engine would be a deal breaker for me. The RV-14 isn't just an aerobatic airplane. It was designed to be a better 2-seat cross country airplane. Depending on how seriously you want to consider it for cross-country use, I think it warrants a serious bit of pondering over the decision. After all, you're not just making the decision for yourself, but for any future buyer if you decide to sell.

The power of the standard IO-390 isn't really too bad, either...so I find it a pretty easy decision to make, if I were facing it.
 
For me, if I'm going to run dual electronic ignitions and/or EFI, I'd want dual alternators if actual IFR or night over the middle of nowhere.
 
It is a big deal - ish...

In our RV-10 we have a dual battery single alternator design, it has worked great with two mags. On the RV-14 I was convinced I was going to install EI on both sides. Then with the (potential) loss of the BU alternator I was moved back to one EI, one MAG, and two batteries.

Now, Dan is asking us to be patient, as Buffalo Springfield says "there's something happening here". I wonder if there is enough space between the ring gear and the engine case to wedge some coils and magnets...

Jason Kreidler
RV-10 Flying
RV-14 Wings
 
Question to the collective: How big of a deal is the lack of back up alternator on the IO-0390-EXP119 for you? I don't necessarily want to start a second battery vs BU alternator debate, but when the rubber meets the road, is it a deal breaker for you? I've had alternator failures and always had a quick out, but it sure would be nice to have that extra alternator.

Some of us do not want a 2nd alternator on the vacuum pump drive. We want our only alternator on the vacuum pump drive.
 
If you read through the weight loss notations, it says "The accessory housing was optimized for modern glass avionics by removing the unneeded drives for a vacuum pump and tach drive."

Much as I love the increased power and reduced weight and drag of the new EXP119 installation, I had to laugh when I read that part of Van's press release. If I were to optimize the accessory housing for the way modern homebuilts are progressing, I'd remove both magneto drive pads/gears and keep the vac pad to drive a second alternator.

I inquired with B&C about whether they could adapt an alternator to be mounted in a magneto location and the answer was that the gears that drive the mags turn too slowly at 1/2 crank rpm. Technically you could mount an alternator there of course, but it would be inefficient (big/heavy for relatively low current output). You could also put a gear box inside the alternator to make it spin faster but that is expensive, heavy, and less reliable.

The idea of an alternator built into (or mounted on the aft side of) the starter ring gear has been kicked around for years, it would be nice to see someone bring it to market. If they do, I hope it's not incompatible with crank triggered ignition systems since many of us are using that with SDS, Lightspeed, Electroair, etc.

I also asked Lycoming about it and they indicated if you want the EXP119 engine with the original accessory case (incl. vac pad drive) they could 'probably' do that for you, but you give up a lot of the weight savings. I didn't ask about price...they might only be willing to do that if you go the Thunderbolt route where you can get more customization.
 
New variation of IO390:

IO390 rear with no mags, no mag gears, no tach drive. With Vacuum pad.
IO390EXP sump and intake.

The mags and mag gears have to weigh more the vacuum parts.

Electronic Ignition and coils will weigh less than mags and mag gearing.


So which variation weighs the least?
 
I inquired with B&C about whether they could adapt an alternator to be mounted in a magneto location and the answer was that the gears that drive the mags turn too slowly at 1/2 crank rpm.

They are mistaken. On 4 cyl Lyc's, the mag turns 1:1 with the crankshaft. The required 2:1 reduction is done inside the mag.

Larry
 
Dimensions rv-14

Can someone give me the dimensions of the QuickBuild fuselage. I need too know if I can get it out of my basements. L* w* h
Thanks
 
Accessory case drive ratios.
 

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Dan, since you have an IO-390 with front-mounted governor you might know: in the TCDS I saw the existence of a "hydraulic pump pad" which I assume is the rear-mounted governor pad. If my assumption is correct, you have a blank cover plate there? And if so, is the drive gear in there too, or did they leave it out?

Reason I ask is Robinson drives their AC compressors from that "hydraulic pump pad". IF the drive gear/pad is there, a guy could make a bracket and a attach a belt-driven alternator there with a very short belt. Direct drive would be even worse than the mag gears since that drive is only 0.87:1.
 
They are mistaken. On 4 cyl Lyc's, the mag turns 1:1 with the crankshaft. The required 2:1 reduction is done inside the mag.

Yeah I didn't check their math but the point remains that (at least in B&C's analysis) the mag drive turns too slow to be a good candidate for backup alternator. The vac pad drive where their standby alternators are designed to mount turns 30% faster (1.3:1 crankshaft speed).
 
Dan, since you have an IO-390 with front-mounted governor you might know: in the TCDS I saw the existence of a "hydraulic pump pad" which I assume is the rear-mounted governor pad. If my assumption is correct, you have a blank cover plate there? And if so, is the drive gear in there too, or did they leave it out?

The pad casting is there on all the standard accessory case covers. Offhand I don't remember if my early kit motor has a cover plate, or just the cast pad, without bore or studs. Either way, there won't be a gear inside; it's part of the governor shaft.
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Ya'll quit worrying. Be patient.

What Dan said. :D

Working with Lycoming on this, and we will soon update our order forms (plan to have it done by Monday evening) with an option to "add back" the upper accessory pad location. This option will add approximately 2 pounds back to the engine weight. There will be no difference in price whether the upper accessory pad is "populated" or not.

So, stand by for that option on our order forms. Thx.
 
Deal breaker for me, my mission is traveling and sometimes IFR. I want to get home and replace that primary alt if and when it fails. The cost and downtime when traveling is something I would rather avoid planning around. A second alt (B&C) is my choice.
 
What Dan said. :D

Working with Lycoming on this, and we will soon update our order forms (plan to have it done by Monday evening) with an option to "add back" the upper accessory pad location. This option will add approximately 2 pounds back to the engine weight. There will be no difference in price whether the upper accessory pad is "populated" or not.

So, stand by for that option on our order forms. Thx.

Wow! This is what you call "customer-driven"! I'm just amazed that Van's could get Lycoming to do this.
 
Wow! This is what you call "customer-driven"! I'm just amazed that Van's could get Lycoming to do this.

Well if the Van's aircraft ticker is correct, 1.5 new aircraft fly every day. If only half those folks buy an engine from Lycoming and an engine averages $35k, you're looking at a $10 million dollar a year customer....

I'd stick an accessory pad on there too. :)
 
There's a big $ step going to the EXP.

So anything to get people to make that step................
 
Wow! This is what you call "customer-driven"! I'm just amazed that Van's could get Lycoming to do this.

We have a great working relationship with Lycoming. And, it was a mutual desire that turned out not to be too difficult to pull off. So, thanks to the team over there for making it happen! And yes, the option availability is customer-driven in large part. We (Van’s and Lycoming) do listen. :)

Our primary goal with this implementation of the EXP319 engine was to maximize weight savings while squeezing out out all the benefits of the increased and optimized horsepower, in part through that weight savings. So one can choose to add a couple pounds back. This seemed a smart option especially since it affects engine-related systems design, the requirements for which reasonably vary from one owner/builder to another. And, we didn’t want to just add it back for everyone, since some people do want the original option for no rear accessories.

The past few days have included some hands-on, third-party flight review of the RV-14 (you’ll get to read about that soon) as well as some flight testing in a variety of our aircraft and for variety of purposes. We had the opportunity to observe and validate some cool things about the 14A with this new engine system during those tests. It’s a beast. :D
 
Well great...

I was trying to justify not wanting that dang engine. Now you dare to give me the option I want!?

I guess I'm brown bagging for life. :)
 
There's a big $ step going to the EXP.

So anything to get people to make that step................

Here is an interesting plot I just whipped up. dollars vs Horsepower using Van's prices.

Slide1.jpg

(you'll have to click on the thumbnail to enlarge it enough to see the trend.
 
The past few days have included some hands-on, third-party flight review of the RV-14 (you’ll get to read about that soon) as well as some flight testing in a variety of our aircraft and for variety of purposes. We had the opportunity to observe and validate some cool things about the 14A with this new engine system during those tests. It’s a beast. :D

Greg, I presume that you're not talking about the FLYING mag article here. Will you be letting us know where to watch for it? Very anxious to hear about those "cool things," particularly since my EXP119 is now on order! :)
 
Greg, I presume that you're not talking about the FLYING mag article here. Will you be letting us know where to watch for it? Very anxious to hear about those "cool things," particularly since my EXP119 is now on order! :)

No, not the Flying Magazine article. Different one. :) And sure, we will be sure to let you know.
 
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