[RV7Guy]

I posted in the Engines section but I think many may have missed it. I've done some research and can't find much. Anyone got any input?

Saw this on Aero-News.net. A new Lycoming turbo charged IO360 for the Experimental world.

Wow, wonder if it will work on a RV? Can the Clone manufacturers be close behind?
http://www.aero-news.net/index.cfm?C...y=/index.cfm
__________________

 

[Tandem46]

Darwin,

Your link works, but just goes to the current Aero-news.net page. This link should work if this is what you're talking about:
http://www.aero-news.net/news/genav...08&ToDate=07/19/2008&Category=/news/genav.cfm

 

[breister]

The "clone manufacturers," specifically Superior, were actually ahead on this with a turbo-normalized firewall forward package exclusively for Lancairs.

However, there were NUMEROUS problems with the package and they have pretty much abandoned it.

Maybe this will get them to try again.

<Edit> Don't forget, the RVs have a VNE which might be exceeded in level flight at altitude with a turbo. Previous posts have expressed concerns that flutter might be experienced with tragic results, although I haven't heard of any in-flight RV breakups. If you decide to go turbo, please be careful!

 

[gmcjetpilot]

Rain on your Turbo parade

Normalizing turbos of Ray Jay have been around since the 1960's.

Lycoming does not recommend turbo engines that where not made for turbo.

Many LONG LONG threads on the subject of how little gain a turbo is in an RV are on this forum if you use the search function.

Bottom line you need to fly into the low teens to get your use out of it. Than you are sucking O2 and than running onto Vne (true airspeed).

Superior had the IDEA to offer an engine with turbo for experimental gave up because the cost of the kit was too great, almost as much as the basic engine. I saw it at Oshkosh in 2004? I called them about something else a year or so ago and asked. That is when they said they shelved it. I think it was before the buyout.

Plus weight and a small cowl would make installation of turbo, wastegate and inter-cooler a pain the back. You really want an inter cooler. There is a RV8 turbo and the plumbing is a monster. He said what kind of speed and fuel burn he got and it was not a quantum leap. Again you have to go up into the teens to get any benefit. Do you fly up there a lot. If all you did was long cross countries over mountain ranges in the Denver area, it might make sense. Most RV's don't get about 3,000 feet for local flights, which make up 80% of they flying RV'ers do. Remember normalizing does not ADD power at all, unless like I say you fly out of Denver (or other high hot airport).

I highly recommend you forget turbo. RV's are not a good match for the machine and mission. If you want more altitude performance get a bigger HP engine, IO360 or IO390 200/210 HP engine. Although 180 HP is plenty for most pilots.

 

[RV7Guy]

Lycoming

Normalizing turbos of Ray Jay have been around since the 1960's.

Lycoming does not recommend turbo engines that where not made for turbo.

This IS a Lycoming from their Thunderbolt line. I love flying high. With the added power you can throttle back, get great efficiency and speed within the proper limits.

Just asking for information. Putting a 6 Cylinder on a 6, 7, or 8 isn't recommended but there are plenty of them flying and they haven't fallen out of the sky yet.

 

[osxuser]

A turbo'd parallel valve is a good idea, but I almost wonder if for the extra weight, a IO-390 or Parallel valve IO-540 wouldn't be a better idea. The turbo gets you back something at altitude, but doesn't help the climb really, and the RV isn't IDEAL for higher altitude flying with it's short fat wing.

That said, i've considered a whole slew of things like this when looking for engine options on my projects. My current favorite idea is a supercharger with a clutch (only around 4-5 PSI of gain, only used at altitude).

 

[rv6ejguy]

If you are climbing high, even a normalized engines makes a big difference in climb rates and times to cruise altitude. At 5K you are down to about 83%, 10K- 69% and 15K- 56% power. My ROC stays pretty steady through 14,000. I've used O2 only once and that was on a test flight for max speed.

I do agree that unless you like to suck O2 and fill the bottle frequently or actually do fly out of high elevation airports and in the mountains, turbos don't make a lot sense on RVs for most pilots.

Since I had the sense knocked out of me a long time ago following some mountain bike endos, I have turbos on both my RVs.

The only substitute for cubic inches is boost.

Done right to the right engine, I don't see many reasons why it should not be reliable and require little more maintenance than an atmo Lycoming. It will add a fair weight penalty though, no escaping that and probably add a bit more drag through increased cooling airflow and intercooler airflow. Always compromises. I haven't looked at the hardware Lycoming uses on this- (I hope it is not the old school stuff they used 30 years ago) but hopefully the factory has done it right.

 

[osxuser]

If you are climbing high, even a normalized engines makes a big difference in climb rates and times to cruise altitude. At 5K you are down to about 83%, 10K- 69% and 15K- 56% power. My ROC stays pretty steady through 14,000. I've used O2 only once and that was on a test flight for max speed.

I do agree that unless you like to suck O2 and fill the bottle frequently or actually do fly out of high elevation airports and in the mountains, turbos don't make a lot sense on RVs for most pilots.

Since I had the sense knocked out of me a long time ago following some mountain bike endos, I have turbos on both my RVs.

The only substitute for cubic inches is boost.

Done right to the right engine, I don't see many reasons why it should not be reliable and require little more maintenance than an atmo Lycoming. It will add a fair weight penalty though, no escaping that and probably add a bit more drag through increased cooling airflow and intercooler airflow. Always compromises. I haven't looked at the hardware Lycoming uses on this- (I hope it is not the old school stuff they used 30 years ago) but hopefully the factory has done it right.

Agreed, but 75% (generally climb HP on the lycs) is 135HP for the parallel valve, only 64% for the IO-390 (So maintainable up to about 12K?). 52% for a parallel O-540 so maintainable up to about 16K...? You see where I'm going. No free ride either way. I know the rotary is a LOT more responsive to boost than a lycoming too, boost tends to reduce life considerably, probably due to higher temps, which could be solved, but like you say, more cooling drag.

Edit: I don't know why I thought you had a rotary, either way though, I'm guessing the sube responds better to boost than the lyc.

 

[rv6ejguy]

Yep, any engine with good port flow responds well to boost (4 valve Sube, Wankel etc.) I only run 38 inches for TO and 35 for climb. Turbos maintain full SL power (100% MCP) to critical altitude. Critical altitude on my present installation is limited by intercooler performance, hence induction temperature rather than the turbocharger which will do 35 inches to about 28,000 feet, depending on OAT with the new compressor. You may be limited by turbine inlet temp, CHT, IAT, oil temps, a fully closed wastegate, N1 limits of the turbo machinery or in some cases, compressor surge limits. Lots to consider, especially above 20,000 or so.

The RV10 twin turbo installation will have far superior intercooling and the turbos are matched for the 8000-17,500 foot mission. Mainly doing this for the smoother ride and a bit more TAS plus the easy ability to catch the favorable winds sometimes. High altitude gives us some more gliding options too. I'm hoping for a solid 2000 fpm at medium weights right through 17,000.

I know most Lyco guys with RVs keep it firewalled in the climb. Is this not common practice? That's how I flew Lycomings.

I'm guessing that more Lancair guys would be interested in the normalized Lycoming than RV guys. They have a higher Vne.

 

[osxuser]

Most everyone I know with a lyc runs 25" 2500 RPM in the climb (CS), with a fixed prop full throttle and whatever RPM they can get (around 2400 usually with a cruise prop...)

Keeping temps down as it climbs would be a REAL challenge at 28" ad 2700 RPM.

 

[rv6ejguy]

Most everyone I know with a lyc runs 25" 2500 RPM in the climb (CS), with a fixed prop full throttle and whatever RPM they can get (around 2400 usually with a cruise prop...)

Keeping temps down as it climbs would be a REAL challenge at 28" ad 2700 RPM.

What? Cooling issues on a Lycoming? First, you can't climb at full power, now this! The armor is becoming tarnished.

Seriously, I've had to lower the nose and power settings on hot days flying Lycomings in the climb to avoid exceeding the CHT and oil temp limits. I expect a turbocharged one would require a few cowling mods to work properly in the climb at altitude. I keep an eye on IAT, coolant and oil temps in the climb but generally all stay in the green at 90 knots IAS now.

 

[JetA4GA]

Has Lyco announced a price for that engine ? If so what is it ?

 

[JetA4GA]

Most everyone I know with a lyc runs 25" 2500 RPM in the climb (CS), with a fixed prop full throttle and whatever RPM they can get (around 2400 usually with a cruise prop...)

Keeping temps down as it climbs would be a REAL challenge at 28" ad 2700 RPM.

With the TIO-360 you would most likely run a CS prop; Wrt cooling, on a climb lower the nose to say 95-100 KIAS since the increased required power is usually partly offset by the increased efficiency of the CS propeller (10-15% typical) giving you better cooling and more or less the same ROC. Increased cooling drag can be offset by the improved design of the inlets, baffles and, outlet where there is usually a lot of margin left for improvement. Many designers think that the aerodynamic principles no longer apply for air travelling in areas where you don?t ?see? it ! Turbochargers are OK but they need one to pay more attention to the installation details.

 

[RV7Guy]

95-100 kias???

With the TIO-360 you would most likely run a CS prop; Wrt cooling, on a climb lower the nose to say 95-100 KIAS since the increased required power is usually partly offset by the increased efficiency of the CS propeller (10-15% typical) giving you better cooling and more or less the same ROC.

The recommended climb is 120 kias. So, you'd have to lower to 130-140 to accomplish this.

Living in AZ and flying in very hot temps is occasionally challenging but can be managed quite easily. I climb at WOT and 2650 RPM. Fully loaded I can get 1000-1200 fpm at 120 kts on 100+ degree days. Oil temps will knock on 200 and my #3 and #4 cylinders can hit 425. If they do I reduce the ROC. Climbing to 10000+ continuous I will end up with ROC down to 700 fpm to keep the temps in check.

I don't expect the Turbo charged unit to do much in the initial stages of the climb but be beneficial at higher altitudes for climb and cruise.

 

[rv6ejguy]

A turbo engine is a waste of time with a FP prop.

An intercooled turbo engine will always have higher drag relative to an atmo engine all things being equal. You will need to address cylinder cooling, oil cooling and charge cooling to have it work well in all flight regimes. Even normalized engines will have higher heat flux to deal with and need more cooling air. Most RVs are a bit challenged already in climb on a hot dayso when you throw in maintained hp and less cooling mass flow at altitude, we almost always see more cooling issues. Dropping the nose helps but the right way to do this is with proper installation and engineering.

 

[rvsxer]

Vne is TAS?

Bottom line you need to fly into the low teens to get your use out of it. Than you are sucking O2 and than running onto Vne (true airspeed).

As I understand it, V speeds are IAS or CAS, not TAS. You can fly up to the redline in smooth air no matter what the altitude.

 

[gmcjetpilot]

Cooled to perfection, no over weight water cooling

What? Cooling issues on a Lycoming? First, you can't climb at full power, now this! The armor is becoming tarnished.

No Ross its not a PROBLEM, it's a careful balance of design and function in an efficent light compact air-cooled, not an heavy water cooled engine.....oh no he did-int.

Besides most supercharged Subies have temp issues, Seriously.

No seriously seriously water cooling does lend it self to turbo because you can run water cooled turbos, but you still have more heat to deal with and thus cooling drag.

Air cooled Lycs are "thermally limited" by design. On hot days and long climbs you do have to keep an eye on the CHT and OT. However my old RV-4 with a O320 could climb direct to 8,500' at gross with out stopping pretty quick. The cooling on a RV-4 was better than any of the Cessna's I gave flight instruction in. RV's are still climbing like crazy at 120 mph in a RV. A Cessna was clawing for altitude at Vy+, step climbing to keep temps down and anemic climb rates.

You can run Lycs & turbos with out an inter-cooler but it's marginal. Many factory planes where certified without inter-cooling. However there is a reason for the large aftermarket for bolt on inter-cooler industry, to fix this oversight of the factory, doing it on the cheap.

I've flown several fire breathing Lyc powered turbocharge twins. There is more work load and special procedures to avoid damaging the engine & components. Low flight levels is nice for smooth ride and getting over the small boomers. However I was paid to fly these fright planes. All I heard from the maintence hanger from mechanics was a LOT of cursing, on working on these turbo engines. First access is limited. Many parts had to be removed and inspected every 50-100 hours. More often than not the part needed to be weld repaired or replaced. I would hate being the owner of a complex turbo from an ownership cost standpoint.

If you really need to go real high more HP and keep the weight down. If you really need to fly high altitude than get a turbine. Oh yea become a multi millionaire first.

 

[Ironflight]

As I understand it, V speeds are IAS or CAS, not TAS. You can fly up to the redline in smooth air no matter what the altitude.

MOST V speeds are IAS or CAS, but in the case of RV's, the limiting speed is due to flutter (or the flutter testing limits), and that is dependent on TAS. This has been discussd quite a bit here on the forums - you can learn more with a search...probably for "flutter".

Paul

 

[JetA4GA]

The climb speed numbers (95-100 KIAS) were based on a non-RV platform; They however represented roughly 2.0-2.2 Vs.

IC an engine provides a means to address the cooling problem at the source; For identical power output, air mass, speed and engine temps, the added cooling drag of the IC will almost always be lower than the added cooling drag of the added mass flow required on the non-ID'd engine.

Putting a bigger displacement of a narutally aspirated engine vs a turbocharged engine (i.e. IO-540 vs TIO-360) will probably add as much cooling drag than the IC cooling drag of the turbocharged engine.

On the new IC'd TIO-360 that is offered, some of the reasons for the IC were to maintain the 8.5:1 (normally turbos are dropped around 7:1) compression ratio (i.e. SFC) of the basic IO-360, improved detonation margins, reduce chamber pressure/temperatures and consequently CHT and oil temps. As for any engine, it also requires more delta P accross the engine to get a given cooling air mass flow through it !

Some of the benefits of the turbos are not only higher cruise speeds above 10K, but lower T-O length as the density altitude goes up and better climb performance where the density altitude is different than what it is at sea level. Also, after say 15K the weight of the turbocharged engine is usually less than the one of an "equivalent" bigger displacement engine. It all depends for what mission you design your a/c for.

 

[rv6ejguy]

For identical power output, air mass, speed and engine temps, the added cooling drag of the IC will almost always be lower than the added cooling drag of the added mass flow required on the non-ID'd engine.

I disagree, having 30 years of experience in turbocharged engines, done extensive flight testing and modification to my intercooled RV6A and currently working with Mike Dacey's Reno Sport Class Venture on intercooling improvements.

There is always a drag/ speed benefit point of diminishing returns with intercooling. Sometimes these concerns are offset by engine life or synergistic effects on other cooling aspects of the engine- oil, cht, clt, egt. In the race car world, we achieved an intercooler effectiveness up to 94% with air to air units. In aircraft we never achieve figures anywhere close to this as we cannot afford the cooling drag associated with using this much mass flow to drop charge temperature to this degree. So we must compromise.

We are primarily concerned with high IATs due to their serious effects on pre-ignition thresholds and high turbine inlet temps. Secondly, we like the cool, dense charge for making max power at the lowest possible manifold pressure. This allows us to reduce the pressure ratio of the compressor, lowering CDT and effectively dropping exhaust back pressure simultaneously by reducing the required turbine shaft energy.

On installations with very high pressure ratios (3.5 to 5-1), effective intercooling mass flow may exceed 35% of total engine cooling mass flow. At Reno, where manifold pressures in Sport Class are now exceeding the 60 inch threshold, relying on air flow through the intercooler cores causes too high of a drag penalty so most entries use water spray bars in the intercooler ducting as well (not to mention engine spray bars and engine ADI).

You'll see extensive development in this area on the Chaivetta Lancairs, NXTs and the Venture where the drag to power to life is a fine line.

On more mundane installations like a normalized Lycoming, CDTs are relatively low because of low pressure ratios at typical operational altitudes. Engine longevity is the #1 concern and a little more drag is not a big deal. In all cases, turbocharged engines with the same thermal limits and margins will have higher cooling drag than an atmo engine. This is a result of losses in the compressor and thermal energy transfer to other mediums such as exhaust to oil and exhaust to charge air. We usually hope this is offset by flying at higher altitudes where airframe drag is lower and TAS increases offset any increase in cooling drag.

Certain older production turbo aircraft are forced to open cowl flaps in cruise at high altitudes because the cooling systems are marginal. On well designed modern installations like the Cirrus uses, engine cooling is not an issue here and intercooler effectiveness is pretty good even up high.

 

[Bob Martin]

Not Really

Keeping temps down as it climbs would be a REAL challenge at 28" ad 2700 RPM.

Not really. Once you get proper fuel flow, it stays cool just fine.
Once I drilled my jet to get 1300 degrees in the hard climb(110mph)
I can climb WOT 2700........I even lean in the climb to keep 1300.