Continental TSIO 360

[gmcjetpilot]

Originally Posted by breister

Hey Richard,

Why the difference? For whatever reason, the aluminum construction used on the Van's models is reputedly more susceptible to flutter -

No Sir, the material has nothing to do with it, it is the design. If you made a lancair our of aluminum it would have the same limits or even greater limits (see SX300 or P51 with 505 mph Vne). A RV made of fiber glass would not gain any speed.

I see where you are going and the link or logic you used but its not true. In a true engineering stand point you can make composite structure super stiff. That would affect something called "aeroelasticity", which is a fancy word for very complicated aerodynamic and flexural (stiffness) characteristics of aircraft. So yes composites could improve flutter, but not in subsonic aircraft like our little piston planes.

[rv6ejguy]

In the turbine Lancairs, some builders add more aileron counterbalance weight to ensure a higher margin from aileron buzz at high speeds. RVs might also benefit from this. Someone could confirm with ground testing.

As someone noted previously, most of the top row Sport Class airframes at Reno have been modified to increase stiffness and flutter margins as they are running way over the original design speeds now. Running in the wakes, propwash and serious Reno turbulence pulling fair Gs and 400+ MPH at 50-150 feet... well everything has to be right or you are dead.

Sometimes these lessons are learned the hard way as with the tragic breakup of Tommy Rose's Venture several years back. Mike Dacey's Venture is seriously beefed up in many key areas now and is running 375+ mph laps.

[breister]

Originally Posted by rv6ejguy

I think you will find that the first combo will start feeling a bit sluggish at 15-18,000 feet, depends what you are used to. You are down to about 50% power at full throttle up there with an atmo engine.

With the turbo, you can zoom around at 25-30,000 if you have the right oxygen equipment and watch the Vne of course. Bruce Bohannon went up to 47,000 with a highly modified RV and special 540 turbo Lycoming several years back.

In practical use, you can catch the good tail winds up high and pull back to 55% at 20-25,000 and get some fantastic fuel economy if that is your game. In the mountains, you can maintain your SL ROC pretty much right to 25,000 if you can cool the engine properly and that is a nice feeling.

Not to be nit-picky, but if you use a high-compression IO-400 from Superior or high-compression IO-390 "Thunderbolt Extreme" from Lycoming (about 250hp at S/L) then 50% hp is 125, or still producing 78% of the max hp of a "normal" IO-320 at 18,000', and only a few pounds heavier.

In other words, it should perform just fine.

For years I dreamed about a turbo, for years my mechanic told me all the horror stories (appropriate as we approach Halloween). Now that I have had enough ownership time to experience the frustration of mechanical woes, I prefer simplicity.

Until, of course, I gain access to unlimited funds...

[rv6ejguy]

My comment meant that a given atmo engine at 18,000 feet will be producing about half its SL power. Obviously a 390 or 400 cubic inch engine will give you more everywhere than a 320.

Certainly if you are flying high a lot of the time, these engines are another way to go. With a 9 or a 6, you'll have to be extra wary of the Vne limit.

[breister]

Absolutely correct. I'm only pointing out that there are two ways to acheive the same result - one with a turbocharger, the other by going high-compression. Some people think high compression is only for racers, and aren't aware that the latter option can provide nearly the same benefit as a turbo without the added complexity, weight, and cooling issues. Too, you don't HAVE to run a high-compression engine at full rated horsepower all the time - if treated well it should be as reliable as a normal compression engine.

[rv6ejguy]

I'd disagree that high CRs have anywhere near the same power potential as turbocharging, especially at altitude. Not the route chosen by any high altitude aircraft designers from the past or today. Turbos are way faster.

For an RV with low limiting speeds, a big inch, high CR atmo engine would be fine but it would never match the climb performance of a good turbo engine. I think that is an important aspect to Richard's needs.

[richvidaurri]

You're right, RVguy, not only is performance at altitude a concern but also aggressive climb-outs over rough terrain in hot humid weather.

My dream is to explore the Rockies from Canada down through the Sierra Nevadas of California and then the Sierra Madre ranges of Mexico.

A good example of Mexican mountain flying is the town of Creel, in Chihuahua. The town overlooks the magnificent Copper Canyon; twenty separate canyons and six rivers which alone would take a week to explore from the air. Well, the Creel airfield (corn field?) is 7,500+ elevation and only about 1,500 - 2000 feet long. And that's the easy part.

At the bottom of the canyons there are any number of impromptu strips suitable for an RV. They are at about 3000+ MSL and surrounded by mountains, crags, canyon walls and other obstacles - I will take a Lycoming TNIO 390X with air conditioning in an RV-7A, lose the fairings, and get over ridges, mountains and weather.


Richard Vidaurri
Alhambra, California

[BikePilot]

That sounds like it would be an incredible trip. I know some folks who have travled more or less that route by motorcycle (there's a huge gathering in Creel/Copper Canyon every year) and have marveled at the picutres. Once done with school I'll at lest run down to Copper Canyon.

Compression can allow you to regain some power and effency lost due to thin air. It won't get as much power back as turbo charging, but helps. Thin air causes power loss in a NA motor partly because there's simply less oxygen there to be burnt and partially because it reduces compression so there are effency losses. I run various types of high preformance motorcycles and it is standard to run much higher compression when racing in the Denver area than is run at sea level. It doesn't get all the power back, but makes a big difference. Of course you probably don't want to do major motor work in order to allow the motor to run safely at sea level so that will limit things somewhat. I suppose if you were planning on running autofuel you could build a motor to run on autofuel at say 6k+ feet if spend most of your time in the mountains, then on the rare occasion where you'll be flying lower than that on a regular basis you could run higher octane av gas.


Anyway, I look forward to pictures from your antisipated rocky mountain flight!

[rv6ejguy]

Nice to see some encouraging words on this thread!

I think many flatlander pilots just don't appreciate how important good climb performance can be in the rocks in HHH conditions, especially in a big downer.

[breister]

Originally Posted by richvidaurri

You know, RVguy, you pretty well hit that nail right where it belongs. Not only is performance at altitude a concern but also aggressive climb-outs over rough terrain in hot humid weather.

My dream is to explore the Rockies from Canada all the way down through the Sierra Nevadas of California and then the Sierra Madre ranges of Mexico.

A good example of Mexico mountain flying is the town of Creel, in Chihuahua. The town overlooks the magnificent Copper Canyon; twenty separate canyons and six rivers which alone would take a week to explore from the air. Well, the Creel airfield (or corn field?) is 7,500+ elevation and only about 1,500 - 2000 feet long. And that's the easy part.

At the bottom of the canyons, where the spectacular beauty is found, there are any number of impromptu strips suitable for an RV. They are at about 3000+ MSL and surrounded by mountains, crags, canyon walls and other obstacles - I think I'll take one of those TIO 390-EXP Lycomings in an RV-7A or -8A. They are the latest and the best.

But just the same and once again, I would like to thank you all for your comments;

Richard Vidaurri
Alhambra, California

There have been some great comments here. I don't take a position for or against turbo for other folks, just want the facts laid out.

As I understand it, the TIO (or, I think they are calling it the TEO) 390 Lyc is 210hp at sea level. As you go up in altitude, you will get full MP but there will be a slight drop in hp due to the turbo air being much hotter (and will create additional heating problems - particularly down low in hot tropical places).

A Superior IO-400 with 10:1 compression creates 250hp at SL and just under 190hp at 8,000'. I believe the IO-390 can be configured similarly. It will be a few pounds lighter than the turbo. At 3,500' hp should be about identical with the turbo. In that altitude range (3,000 - 8,000) performance between the two should be almost indistinguishable - but the turbo will cost more money and burn more fuel and require more maintenance and may pose additional cooling problems.

If you have the money and the patience to work out all of the cooling challenges, I say go for it. If you don't want to be one of only 1% of all RVs with a turbo Lyc, then I would opt for the extra compression.

One last factor to consider - what happens when (not if) you break down some day? I wonder how hard it would be to get a mechanic to work on a turbo in Chihuahua?

Whatever you decide - keep us informed!