Aerovee turbo

[fastj22]

Looks like some movement on the turbo at AirVenture. I'm heading there tomorrow and plan to pin Jeremy down on what the details are.
10,000 price tag, 100HP at all altitudes. Thoroughly tested by Sonex. This could be a game changer. ONEX compatible?

[MichaelFarley56]

Not sure about Onex compatible but I'm 99.99% sure that's a mission goal. They want a setup that works on all AeroVee's and cowlings.

The setup itself looks great. I just got back from Oshkosh and spent a lot of time looking at the engine mock up, as well as the actual test engine on the stand. Jeremy even started it up during Monday night's Open House for those who wanted to take a look at the testing procedures. It looks like a clean setup and should be really nice.

A few things I remember hearing about:

- It's not done yet but they're doing a lot of testing on it. There's HUGE demand and the factory recognizes that request. They're performing at least 3-4 test runs per week to work on it.
- Performance is looking really good. They're running very low boost levels (around 4" of boost) which certainly should provide around 100 h.p.
- Heat is the issue they're working on. It's not a huge deal, but on some of the engine runs with long duration test runs, the oil temp was getting fairly high. There's one (stock size) oil cooler for the engine and turbo, so that's something they are working on. They did add a larger oil sump to try and help in that area. The good news is the heads are running surprisingly cool on the test stand.
- It will have a secondary oil pump to provide oil to the turbo. It will bolt right onto the cover of the stock oil pump.
- No word yet on final cost or when it's available, but rest assured they are working hard and are hoping to have something soon.

I can't wait either!

[daleandee]

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[MichaelFarley56]

Thank you for your thoughts Dale. I agree with you on your thoughts in the matter. Like you, I'm not all that concerned with the weight of the installation even if its just slightly over 200 lbs. I don't perform much acro so I'm not all that concerned. In fact, with the stock AeroVee, if I put two people in the plane and only have a few gallons, I run into an aft c.g. issue so having a little more weight up front certainly won't hurt.

The bigger concern to me is the heat issue, both in terms of oil temps and head temps. I can only hope that the low boost being used, combined with extra fuel to aid in the cooling, will keep head temps under control. The oil temp will be an interesting study; perhaps a second cooler may be necessary. Jeremy did say that, after testing different setups, the "Sonex-stock "lower cooler setup where the cooler is below the block may still work with the turbo. If that's the case I'm sure a larger cooler can be used.

Time will tell how the project goes...I'm still keeping my fingers crossed!

[daleandee]

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[MichaelFarley56]

Thank you for posting the video Dale! I was standing a few people behind you, drooling over the turbo kit!

A few things to remember...

First, I don't want to put words in Jeremy's mouth so these are 100% my own thoughts on the subject, but I don't think that limiting the power to an 80 h.p. level for sea level takeoff was what Jeremy meant. I do think there will be a maximum manifold pressure/boost level to be used for takeoff so you don't exceed the limits of the internals, but remember that the entire purpose of this turbo system is to get the AeroVee up to around 100 h.p. In other conversations with Jeremy throughout Oshkosh, he stated that the goal of a 100 h.p. engine for $10,000 was the goal since there aren't any readily available, and there seems to be a HUGE customer demand for a little more power out of the AeroVee. If the engine is limited at 80 h.p. that sort of defeats the purpose.

My guess is that there will be some sort of power limit (manifold pressure) which will provide around 100 h.p., but it will be up to the pilot to not exceed that power limitation. So, in essence, when you perform a takeoff, you will add throttle until you reach a certain point and then stop adding more. This is actually quite common; as a Cirrus insturctor, I've taught many people this same technique on takeoffs in Cirrus aircraft. Also, any Pratt&Whitney PT-6 is the same thing; if you take a PT-6 and apply full power, you will have maybe up to 20 seconds until the engine melts and you have a very expensive paperweight. I have a few hundred hours in KingAir 350's and have never pushed the throttles past around 75% of the travel of the lever for this reason.

Again, just my thoughts but I think the turbo AeroVee will be able to produce around 100 h.p. (more if you want to blow up the engine) all the time, but it will take the pilot to limit power output at around 100 h.p. by limiting the throttle movement.

At least I hope!!

[fastj22]

For me, producing 100HP at my field elevation of 6900ft is the goal for takeoff and climb out. After I'm up and in cruise configuration, 80HP or 80% throttle will be fine.
Since I plan on flying over the Rockies frequently, it would be nice to have that extra power in the bank if I need to climb quickly to clear a pass especially in a downdraft.

[vigilant104]

In the video, Jeremy was doing a couple of other things when the question about takeoff HP was put to him, so my preference is to wait for a bit more clarification. If the 80HP isn't likely to be available at TO and climb, I think that would be a change from what was presented in the webinar some months ago.

About head cooling: Any thoughts on which is the more demanding situation: SL or at altitude?
Back of the envelope noodling: Assuming the limiting factor is the ability of air to remove heat from the metal of the heads, at SL we have denser but warmer air, at altitude we have less dense but cooler air. I don't have any practical experience with this. My >guess< would be that head cooling is more difficult at altitude than at sea level since the decrease in the mass of the available cooling air (a function of the air density) is more significant than the change in ΔT (difference between the head temperature and the cooling airflow) with altitude. For example, going from SL to 10K ft, the air density is reduced by 25%, but the ΔT changes by only 12% (assuming a CHT of 325 deg F). I think the forced convective cooling rate is directly proportional to both the ΔT and the air density, and if I've got that right then cooling will be easier at Sl than at altitude. Of course, if we're generating less heat at altitude (burning less fuel, making less HP) then there might be no problem. But if an NA Aerovee makes 80 HP at SL and we ask it to make 80 HP (with turbo) at 10K ft, the heads will have a harder time shedding the heat at altitude than they had at SL, even though it is cooler up there. (I think).

The actual calculation of heat transfer is complex, involving Reynolds numbers of the transfer surfaces, assumptions about flow turbulence, specialized constants, etc. But a possibly applicable study of expected forced-air cooling effectiveness at SL and at altitude (seehttp://legacy.nrao.edu/alma/memos/html-memos/alma203/memo203.html) does indicate cooling is reduced at altitude.

I will immediately shelve all comments above in deference to anyone with practical experience or a better understanding of the applicable forced convective transfer equations.

Mark

[Rynoth]

Re-posting this that I just read on the yahoo forums:

The coolest thing I heard from John in his forum on the various Sonex planes was that the turbo will deliver this year and for less than 10K. I know they have said soon previously and suggested it should be less around $10K. This was the first semi-firm delivery time I have heard as well as a more formal announcement on price. He also said they were getting at least 100HP at takeoff with the turbo and a consistent full 80HP in flight.

Carl

If this happens I'm very excited, and only hope it will be ready as a complete package when I"m ready to buy an engine!

[MichaelFarley56]

Hopefully we will hear something from Sonex about this sooner than later. Like others, I'm also excited for this announcement and hope it pans out for the factory. There are certainly a lot of questions to be answered but I'm excited that they are making progress on the package!

Very cool!