What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Turbine on RV ?

spatsch

Well Known Member
Looking at the latest announcements from TurbAero I was wondering why one would ever put a turboprop on an RV (There are airframes where a turbine obviously makes sense but I am asking about RVs in particular.). Now I get the 'cool' factor. Who doesn't like the smell of burned kerosine? I also don't want to start a debate here about the merits of experimentation. If you like experminenting please do. What I am trying to understand are some of the underlying physics/costs and not being an aeronautical engineer or engine expert I am having a hard time working this out by myself.

I see 4 different areas of comparison here:

1. Takeoff roll
2. Climb to altitude
3. Cruise at altitude
4. Cost

So let's be concrete.

Let's assume we have an RV-8 with an IO-360 M1B and compare that to an RV-8 with a TurbAero Talon turbine.

Anticipated performance and cost of the Talon engine can be found here:
https://turb.aero/community/resources/two-most-commonly-asked-questions

Performance numbers for one configuration of an IO-360 M1B on an RV-8 can be found here:
https://www.vansaircraft.com/rv-8/#aircraft-details-2

Van's claims 203 mph TAS at gross with 75% power (which is typically around 9gal/hr lean of peak for me at that altitude) and 575 feet take off distance which I assume was done on a paved runway.

So coming back to my 4. areas. How can I compare:

1. Takeoff roll

Now the Talon engine sates it has 200hp at sea level which according to Van's would save me 75 feet on take off distance. That assumes that it develops power as quickly as a piston engine. Do turbo props do that?

2. Climb to altitude

I am actually not sure how to make a good comparison here. Van's claims a 15% inmprovement in climb rate at see level for another 20hp but I rarely climb at max climb rate. I typically climb at 500 feet a minute or so which already gives me a pretty decent ground speed while climbing. So how do you compare that?

3. Cruise at altitude

Van's shows his numbers at 8000 feet which is roughly the altitude I cruise at and feels quite comfortable. At 75% power that would be 135HP at 9gal/h. Now I don't fully understand how you measure power on a turbine but assume that shaft power would be the equivalent to the power spec of a piston engine. Using that assumption the Taleon engine should be able to make 180HP at 15-17gal/h at that altitude.

So that gives me 1.33 times the power. Now I was told that power and speed on airplanes is related roughly by the power of three (is that correct?). So that would provide a speed increase of approximately 10% taking the cruise TAS to 223mph. Flying higher will be somewhat better in fuel efficiency but I really don't want to have to always cruise with oxygen which limits me to 12500 feet. Also TAS is limited to 230mph per vans.

I don't know how to compare this at 12500 feet which would be the highest altitude I am willing to fly permanently and should be more favorable to the turbo prop.

4. Cost

The Taleon engine will cost 80-85k$ . Lycoming will cost 43k$ with dual EMAG.

At my typical altitude I would get 10% more speed put use more then 50% more fuel. Now I know AVGAS is more expensive then Jet A but looking around its usually cheaper by 1 dollar or so which is about 25%. Also the IO360-M1B can be operated on unleaded fuel so AVGAS is not stricly required. It's just the convenient choice in the US.

So from all I can see the turbine is strictly more expensive for a 10% speed increase. Is that the correct way to look at it?


Again I understand very little about all of this and probably made many mistakes above. The reason for posting this is to learn something.

Thx

Oliver
 
While I’m sure some can rationalize the cost increase, the severe degrade in range locks the plane into a limited mission profile.

While you can add more tanks, this just continues down the sub optimization curve (more weight, more fuel burn, reduced range, repeat..)

So bottom line (as are most RV build considerations) what do you want the plane to do?

Carl
 
Good point about range. As for mission profile I like flying cross country in the US VFR. I rarely fly more then 3 hours between fuel stops just because I need to use a bathroom myself …. .

It’s pretty clear to me that if you are just hovering around your home airport at a 1000 feet a turboprop makes absolutely no sense…. .

Thx

Oliver
 
Oliver, I think you have an excellent understanding of the puts-and-takes, and the final result which is “you do it because its cool, not because it makes sense!”

I say that as someone who owns a turbojet powered homebuilt. At least it was DESIGNED to be powered by a turbojet. But it is still based on an aerodynamic package originally designed for piston power (genetically, it is still a Sonex). It is cool, fun, unique, and great way to show off. But you can out-cruise or out climb it in a Rocket and burn considerably less fuel in the Rocket.

All aircraft design starts with a mission and an engine, and the design work grows from there. So if you decide to radically change the engine without radically changing the design, you end up with a compromised package. The RV’s were designed around the basic Lycoming engine, and using something else will compromise the performance or operational envelope. That’s just how aeronautical engineering works - no matter how much we might wish it didn’t.

Which doesn’t negate a persons dream to burn kerosene and make a splashy entrance, so long as you accept the compromises. As I say about my little turbine, on any given weekend, I can be the guy that shows up at the lunch spot in the jet……

Paul
 
Last edited:
If you don't have access to gasoline, and it meets expected cost, perhaps it might be a viable (and more supported) option compared to a diesel? <shrug>
 
Paul summed it up well. The only other “real” advantages of kerosene vs avgas: it’ll climb much higher (and exceed VNE), supposedly more reliable, lighter (but needs more fuel/weight to run) and no avgas shortage issues. The cool factor trumps all else though ;)
 
For climb, I expect any engine that isn’t a traditional air cooled piston will outclimb most Lycoming powered RVs just by the nature of not being temperature limited. Maintaining L/Dmax AOA will be optimal compared to most who need a shallower climb profile for cooling.

In cruise, since the turbaero design will be flat rated, as I understand it, a stock RV will be Vne limited. This now comes down to flying a little different and is going to be oriented around what your mission is.

The other factor is, of course, single lever control. Being able to distill engine management down to just “move the PCL to set power” is appealing to some people compared to our traditional throttle/prop/mixture combinations.
 
In general turbines (turboprop in this case) have worse fuel consumption (lb fuel/brake horsepower/hour) than reciprocating piston engines. In the case of the TurbAero, I believe they are incorporating a recuperator (takes some of the waste heat from the exhaust and pre-heats the intake air). This is not the norm for aviation turbine engines due to weight considerations. If it works as intended, it decreases fuel consumption substantially. One of the limiting factors in scaling down turbine engines is the compressor and exhaust turbine blade to casing clearance. As the turbine engine gets smaller the losses from this clearance increase out of proportion to the size scaling. So from the TurbAero website, the projected fuel consumption is 0.56 lb/bhp/hr compared to a Lycoming (I)O-360 of 0.41-0.46 lb/bhp/hr at 70% power (ie cruise at wide open throttle at 8000 ft). So the turbine will burn about 35% more fuel for the same speed and altitude. Which means range is 35% less. In the case of TurbAero I wish them good luck, but I would wait until they have a few hundred flying (tens of thousands of Lycomings flying) before I considered one.

There is at least one (maybe more) RV-10s with turbine engines. Have a look through the forums to see how the owners like them.
 
Also consider the extra year in build time it will take you to redesign the engine mount, cooling, exhaust, firewall forward, cowling, etc.

Is there a prop that will work for this engine/airframe combination? What happens to W&B?

Does the company have a flying aircraft with this engine? Or even just an engine spinning on the dyno? I love experimental but I don't want to be in the group of test pilots running the first few airframes on a brand new engine. Show me a reasonably priced turbine fw-fwd package flying on RV's and at least a few hundred no-issue hours and I'm interested.

I fly my airplanes as family haulers, breakfast seekers, and trip-with-the-wife adventures. There are some of us that fly experimental as "I want to do experimental aviation and be a test pilot." Those are very very different missions with different risk profiles.
 
What problem do RVs have that a turbine will solve?

Power? The airframe doesn't need more power, most of them are bumping up against airspeed limits (practically speaking, Vno), so don't need more power.

Cost? Lycomings are expensive, but turbines are even more. Double by the cost estimate on the TurbAero site.

Reliability? I'll believe this one once the teething problems are worked out. Pistons flying back and forth, valves clattering, etc., lots of high stress parts to go wrong. Established turbine engines are more reliable than equivalent piston engines.

Fuel economy? Turbines loose here, until they start getting bigger. Went full nerd at work yesterday. PW-120, in cruise at FL250 and -50*c, was making 1200hp consuming 550lbs/hr. Works out to 0.46lbs/hp/hr. Now to fit a PW-120 and the 13' diameter propeller on my plane. :D The TurbAero engine is nowhere near this efficient at a 10th the size.

Simplicity of operation? Single or two lever control is big. No mixture, just power lever and propeller control. Although this already happens with EFI options (EFII and SDS).

Burns Jet A? Don't see any established Jet A options. If gasoline really isn't an option, this could be a possibility. There is another thread about a piston diesel/Jet A option.

Altitude performance? RVs with the Vne being in TAS really hampers altitude performance potential. Not sure the airframe could really utilize that power at altitude. Just not a good match-up of engine altitude capability with airframe altitude capability. If we wanted to fly at 160kias (220ktas) and FL200, we'd need a different airframe.
 
Turbines make their money in the flight levels. Or at least in the O2 levels.

Below that they're not that efficient.
 
It would sound and smell great, be amazingly smooth and be really cool. I've thought through it too and arrived at the same conclusion. My son designs turbines for GE, and I've picked his brain many times to see if I'm missing anything and these just aren't solutions for down low.
 
A couple observations:

Unless the turbine is flat rated, don't expect altitude performance to be much better than a naturally aspirated piston engine of the same SL power. Turbine efficiency improves the higher you go but inlet mass flow decreases at the same rate as on a piston engine.

The TurbAero engine hopes to improve efficiency considerably over other turbines by using a recuperator. It remains to be proven that this will work sufficiently well and be cost effective. It's a challenging engineering and manufacturing goal.
 
It appears the engine is flat-rated to some degree. The following quote is from the TurbAero website (linked in post 1).

Please note that at ISA conditions, the power available from the Talon is 200hp up to 8,000’ with maximum power at 10,000’ and ISA conditions being around 187hp

Granted, nobody is going to cruise around at max take-off power and everything redlined (turbine temperatures, engine speeds), so reasonable climb/cruise power settings will likely be available comfortably above 10,000. 147hp (74% of 200hp) is still available at 20,000'
 
This post will be a little long so you might want to grab a coffee before you settle in to read.

There are a lot of excellent discussion points raised in the posts above and I'd like to take this opportunity to address some of them. This first response will be of a generic nature, and I will then endeavour to respond to the individual posts where I think a response would add value or clarity to the discussion.

I need to start by making it very clear that the Talon is still under development. We have completed the design of the prototype and are currently having components sourced/manufactured for that prototype engine. All figures that we have or are putting out there are predictions only at this stage. It will not be until we have run the engine and have obtained verifiable data that we will be able to publish actual performance data.

Our performance or specification predictions are based on the design work and analyses that our engineering team have carried out, using industry standard software that is proven to be extremely accurate. Our turbomachinery, combustor, fuel delivery, rotor and bearing systems are fairly conventional so their performance can be predicted with a high degree of accuracy. Our recuperator component has added a measure of complexity to designing a well-balanced system, but again, there is software that can fairly accurately predict heat exchange technology performance. The technical challenge with our recuperator is to get the performance that we would like in a small package, that doesn’t cost an arm and a leg, and to be actually able to build it.

Another generic statement that I would like to make in relation to discussion around our engine is that there is a lot of knowledge but also misunderstanding out there about turbine technology. Also, generalities have been made that do not apply to specific circumstances, technologies or products. When discussing this technology, I would encourage participants in this forum to be open to learning new stuff and be prepared, through education, to be open to considering changes to preconceived ideas or “prior knowledge”.

If you would like to understand about our technology better and you are attending SUN ‘n FUN 22, please come and visit our display and speak directly with our Chief Technology Officer who is leading our design effort. He is very good at answering the technical questions in a way that either the most technical or least technical person can understand.

With that now said, let me address some of the points that have been raised.

The first point is that power is power. 200hp is 200hp regardless of whether it is from a piston engine or a turbine engine. For the same power on the same airframe, the performance will be identical.

However, there are several factors to be considered that could influence aircraft performance:

1. A Talon installation will likely allow the use of a more aerodynamically efficient engine cowling that should result in less drag for the airframe. What this means is that for an identical power setting, the turbine RV with the cleaner cowling would fly faster than the piston RV. Alternatively, for an identical speed, the turbine RV would use less power.
2. The Talon should offer 200hp for take-off at sea level, a maximum power of 187hp at 10,000’ and a maximum power of 147hp at 20,000’, whereas the IO-360 M1B quoted in Post #1 offers a maximum power of 180hp at sea level, a maximum power of 128hp at 10,000’ and a maximum power of 86hp at 20,000’ (from Figure 3-26 of the Operators Manual). Maximum power available will limit the performance of the aircraft (take-off, climb and cruise). Because the Talon is flat-rated to around 8,000’, it will have a power advantage over most of the naturally aspirated IO-360 variants at altitudes above 5,000’. If you have a high elevation or high density altitude home airport, the Talon’s performance should be a positive.

Switching to the topic of fuel consumption, any individual considering a powerplant needs to determine what their most common mission profile is, or if not the most common mission profile, at least the most limiting mission profile that they will fly.

As Paul Dye indicated in Post #4, you need to define the mission before doing an analytical comparison of fuel consumptions. Once you have defined the mission and set the parameters for doing the comparison (power required and altitude being key factors), then be careful to compare apples to apples. Specific Fuel Consumption comparisons are not valid when comparing a JetA burning aircraft to an Avgas burning aircraft due to the different densities of the fuel (JetA being around 10% more dense than Avgas). What this means is that a turbine that has a SFC of say .55 lbs/hp/hr will actually be burning the same volume of fuel per hour as a piston that has a SFC 0f 0.50 lbs/hp/hr. Since we buy fuel by the gallon and the tanks hold a set number of gallons, volume of fuel is most important to us (except where weight limits are more critical than volume limits).

A secondary but other important factor is the cost differential between JetA and Avgas. In many parts of the US. JetA is around 10-20% cheaper than Avgas. Meaning that the turbine can burn 10-20% more fuel before the fuel cost for the piston becomes cheaper. In parts of Europe, the cost differential between JetA and Avgas is much higher, so the fuel cost equation is more in favour of the turbine in Europe than for the piston.

I will give one example of a comparison for the forumites to ponder:

The aircraft concerned is an RVxx and this owner’s typical mission is a 3 hour flight, going as fast as he can to minimise his time in transit. Let’s assume the piston engine fitted is the IO-360 M1B referred to in Post #1.

I’m going to make several assumptions about the power required to achieve the maximum speed the owner of this example aircraft is comfortable to cruise at. I will also use the fuel prices from today at KOSH for this example (Avgas - $5.89 per gallon; JetA - $4.99 per gallon)

Sea-level comparison:
Assumption – The aircraft requires 150hp to cruise at its maximum cruise speed (TAS).
Piston – Burns 9.2gph at $5.89 per gallon = $54.20 of fuel per hour (Figure 3.6 from the Operators Manual)
Turbine – Burns 14.5gph at $4.99 per gallon = $72.40 of fuel per hour

Over the 3 hour flight, the turbine burns 15.9 gallons of fuel more than the piston and the fuel cost is $54 more for the turbine.

10,000’ comparison:
Assumption – The aircraft still requires 150hp to cruise at its maximum cruise speed (TAS).
Piston – (cannot offer 150hp at 10,000’ but at it’s maximum power of 128hp, it will be burning 11.0gph at $5.89 per gallon = $64.80 of fuel per hour (Figure 3.6 from the Operators Manual – Max power curve because 128hp is maximum power available at 10,000’)
Turbine – Burns 12.7gph at $4.99 per gallon = $63.40 of fuel per hour

Over the 3 hour flight, the turbine burns 5.1 gallons of fuel more than the piston but the fuel cost is $4 less for the turbine, but also remember that the turbine is operating at 22hp higher than the piston so the aircraft will be cruising faster, making the flight shorter. This makes the economics even better for the turbine as far as fuel cost is concerned and actually means that there may be very little differential in the amount of fuel used for this flight.

20,000’ comparison
Assumption – The aircraft requires 120hp to cruise at its maximum cruise speed (TAS).
Piston – cannot offer 120hp at 20,000’ but at its maximum power of 89hp, it will be burning 8.7gph at full throttle (Figure 3.6 from the Operators Manual) @ $5.89 per gallon = $51.20
Turbine – Burns 9.0gph at $4.99 per gallon = $44.90 of fuel per hour
Over the 3 hour flight, the turbine burns 1 gallon more fuel than the piston but the fuel cost is $18.90 less for the turbine and the turbine is offering 31hp more than the piston so cruise speed will be much better for the turbine, offering way better fuel economics (better range when cruise speeds are considered, less fuel cost).

Conclusion:

What the above example demonstrates is that under certain scenarios, the piston offers better range (less fuel burn) and a lower fuel cost. However, for a different scenario, the turbine can offer more range (less fuel burn) and a lower fuel cost.

So, from a basic range and fuel cost perspective, the typical mission of the aircraft is important to determine whether a piston or a turbine makes sense for you.

So that is fuel considerations covered.

Now there are weight, size, reliability, scheduled maintenance requirements, TBO, customer support (spare parts, access to maintainers, participation in a pro-active Health and Usage Monitoring system program etc.), coolness, sound, smoothness of engine, cost to purchase, cost of overhaul, cost of inspections, single lever control and simplicity of operation (safety), automatic engine protection systems (safety and simplicity for pilot), and a myriad of other factors/features that need to be considered.

Once we have run our engine and thoroughly tested it, we will have the data that you need to make an educated and valid comparison of engine options. When it comes to that time, I encourage anyone considering the buy decision to take the time to define their mission profiles, determine what the key factors are that they need from their engine and then do a valid apples to apples comparison between the options.

The good news is that while the turbine will not be the solution for some or even many, at least it will be an option. It’s always better to have choice than no choice.
 
Thank you for the detailed explanation.

In my initial post I actually had outlined some constrains of my mission profile. One of my main constrains was no oxygen required. So that limits me to 12500 feet. I guess I don’t even fly at 128hp at 10000 feet as my actual fuel burn is around 9gph at that altitude.

I would also be worried about the relatively low Vne of the RVs. E.g. for the 20000 foot number will that keep my RV below 230 TAS?

Thx again!

Oliver
p.s. I am all for choice. I was just trying to figure out if that is something for me and my RV.
 
The only problem I see is that for a flight today, there is no turbine for the RV-XX, so the burn and savings rates don't matter, because there's no turbine to experience them today.

Maybe a turbine will be available by your next top end overhaul. Maybe it won't. There was another company ~10~12 years ago that made promises, and even taking deposits. That company no longer exists as far as I can tell.

If you want to fly in the next 1~3 years, it won't be with a turbine.
 
Last edited:
Thank you for the detailed explanation.

In my initial post I actually had outlined some constrains of my mission profile. One of my main constrains was no oxygen required. So that limits me to 12500 feet. I guess I don’t even fly at 128hp at 10000 feet as my actual fuel burn is around 9gph at that altitude.

I would also be worried about the relatively low Vne of the RVs. E.g. for the 20000 foot number will that keep my RV below 230 TAS?

Thx again!

Oliver
p.s. I am all for choice. I was just trying to figure out if that is something for me and my RV.

Hi Oliver,

You did identify several important mission parameters so you were thinking along the right lines and you were certainly asking the right questions. When our engine is ultimately being delivered to customers, I'm sure you will have done a diligent assessment of it's suitability and appropriateness for your aircraft.
 
The only problem I see is that for a flight today, there is no turbine for the RV-XX, so the burn and savings rates don't matter, because there's no turbine to experience them today.

Maybe a turbine will be available by your next top end overhaul. Maybe it won't. There was another company ~10~12 years ago that made promises, and even taking deposits. That company no longer exists as far as I can tell.

If you want to fly in the next 1~3 years, it won't be with a turbine.

Greg, you are 100% correct, it's not available now.

At this stage, we are happy for people to keep their eye on us so that when we do have a product to deliver, those that are ready for an engine will know all about it and will have done their homework. We don't want any deposits now, but we would be happy to receive encouragement for giving it a go and trying to make a difference.

One thing that came out of our display at Oshkosh last year was that often we heard "I'll believe it when I see it" which is a very valid approach, but almost always, it was followed by "but thanks for giving it a go. I've been waiting to see someone try this for a long time."

We understand the skepticism. It hasn't been done successfully before, it is technically challenging, the development costs an arm and a leg, some have tried and failed. Our intention is to be the one that succeeds. Time will tell whether we succeed or not, but we certainly appreciate the words of encouragement that we get and we will be giving it our best shot.
 
When do you anticipate that your engine will ultimately be delivered to customers?

Greg, our timeline consistently shifts to the right but we are making both tangible and positive progress all the time with components now being made.

We have the prototype to assemble, run and test. There will be design changes that will need to be made as a result of testing, as well as product enhancement prior to freezing the design for production. So more prototyping, testing and redesign then repeat.

An aggressive and relatively trouble-free program could have a solution in 18 months or less. Realistically, it will be further to the right but how far will depend on the issues that arise during testing. We would like to say Q1 2024, so around 2 years from now. What I can say is that we will have a whole lot more clarity around the timeline once we have run the prototype which should be later this year.

I'm sorry I cannot be more definitive. There are just too many unknowns and variables in play at the moment.
 
Thanks for the details, a couple quick thoughts.

  • What are the fuel requirements to climb to those altitudes?
  • What is the fuel consumption during a go-around and return to landing?
  • Please don't forget to add VFR or IFR minimums to your calculations.
.

Without knowing how much it burns to climb to those altitudes it's hard to calculate endurance. Remember the largest 2-seat RV fuel tank is 50 gal in the RV14, next is 42 gal in the RV-7/8.
 
Some good points here.

A point on the Lycoming fuel burns though. Most folks operate LOP in cruise with BSFC figures closer to .42, rather than book Lycoming values ROP..

This would put the figures closer to:

128 hp 9 gph
86 hp 6 gph

I've seen fuel burns below 9 gph on a 540 at 20,000 LOP, WOT, 2400 rpm.
 
I spent some time in the booth last year at OSH. Very interesting concept.

I am watching the development closely and I am happy I stumbled on to this thread today. I am one that hopes this achieves it's predictions.

I started a 14 build, sold it and bought the airplane I really wanted all along. Since I was 2 years in to the 14 I didn't want to start all over. Now that I have my current 8 pretty much where I want it, just needs some attention to the paint and interior, probably next year. I have decided to embark on a sloooowwww build 8. This will be my retirement ride.

With what we are seeing in the availability of fuel now and an "over the horizon" view of the "clean energy" environment we may be forced in to by the end of the decade, alternatives will likely be necessary.

For my new airplane it's going to take at least 5 years to complete (starting next year even though the tail kit will probably be here next month). The engine choices will likely be an IO-360 custom build at Ly-Con with the Fly EFII system to accept what ever version of a UL the industry forces on us. Or the Turb Aero if it meets the mission profile and its advertised claims, and the availability of the firewall forward parts. I figure I am at a minimum 3+ years from a decision point based on today's supply chain issues with Lycoming (cylinders ordered today will be here July of 2023 in case you're wondering).

The comparisons at 10k feet seem to be a bit misleading or maybe my line of thought is wrong. They seem to all be at WOT with the Turbine likely capable of more than 180 HP and the piston about 50 HP less. I am reasonably sure that an RV8 with a WOT at 10k feet pushing 180hp is going to be crowding if not exceeding the 200kt TAS limitation. You can always pull it back and achieve the desired fuel flow for the days flight.

I really hope you/they pull this off. I am planning to explore increasing the fuel capacity to at least 50 gallons when the time comes. I'm good for 3 hours at the most before I need to get up and walk around. That should be about right with VFR reserves.

Finally, the aesthetics of the TurbAero cowling (when there is one) on a FastBack 8 turning the Whirlwind 300-3B/A prop are just intoxicating. . . :D Then there is the sound. . . C'mon, admit it, you kids still draw pictures of your future airplanes while noodling away the day at work. . . right? If not, you're probably a Boeing guy and don't have a desk.:p

Keep up the work! I for one am tired of the 100 year old tractor and hopeful for a future that improves performance, safety and reliability. If it burns banana peels, all the better.

YMMV and probably will. . .
 
it would be nice not to ride a loud lawnmower in terms of vibrations. I presume this means one would arrive less exhausted and tired. I often fly lower because it reduces tiredness thereafter (and improves sightseeing), too. one should assign minimum wage to one's own later time, too, so modestly more costly on fuel is ok for many (not all). finding spare parts and mechanics will be a big deal. (it better never break down!) spooling up the engine on go around could be a concern.

if rotax comes out with higher-power engines at lower prices, it could be competition, too. competition is good. we have had too little competition for too long a time. (I do understand why.)
 
I've seen fuel burns below 9 gph on a 540 at 20,000 LOP, WOT, 2400 rpm.

I routinely get 9.3-9.4 GPH when cruising at 165 KTAS at 14K' Haven't gone higher yet. This is over 1 gph less than at 10K, so fully expect well under 9 if I ever go to 18K (limited by basic med).

Larry
 
Greg, you are 100% correct, it's not available now.

At this stage, we are happy for people to keep their eye on us so that when we do have a product to deliver, those that are ready for an engine will know all about it and will have done their homework. We don't want any deposits now, but we would be happy to receive encouragement for giving it a go and trying to make a difference.

One thing that came out of our display at Oshkosh last year was that often we heard "I'll believe it when I see it" which is a very valid approach, but almost always, it was followed by "but thanks for giving it a go. I've been waiting to see someone try this for a long time."

We understand the skepticism. It hasn't been done successfully before, it is technically challenging, the development costs an arm and a leg, some have tried and failed. Our intention is to be the one that succeeds. Time will tell whether we succeed or not, but we certainly appreciate the words of encouragement that we get and we will be giving it our best shot.

I love the work and what you are trying to accomplish. I think however I would target slightly more power. The under 200hp market I suspect is somewhat cost sensitive. I think you might find more acceptance in the 250 to 350 HP range. It may be you already have plans for HP growth with the initial design. If not I would certainly consider options for more power as you test.
 
I routinely get 9.3-9.4 GPH when cruising at 165 KTAS at 14K' Haven't gone higher yet. This is over 1 gph less than at 10K, so fully expect well under 9 if I ever go to 18K (limited by basic med).

Larry

That sounds right - I routinely see between 5.8 to 6.5 at altitudes between 15 and 17 in my 360.
 
Great ideas

If I had a dollar for every promising advertisement I’ve seen in engines ( and gear reductions) over the past 40yr, I’d be a wealthy comrade. I can’t help but wonder what the next 50yr will bring after I’m gone from this earth but my money isn’t on regen turbines. At least not yet……. But it is a nice
Thought
 
Last edited:
With the price of Lycomings increasing by leaps and bounds over the last few years, turbines and engines like the Adept V6 may actually start to fit into similar pricing structures soon...

Regen equipped turbines are a sound concept to reduce BSFC- well proven in stationary applications. Someone just has to prove they can do it for GA type aircraft by getting a bunch in the air and accumulating flight time.
 
I love the work and what you are trying to accomplish. I think however I would target slightly more power. The under 200hp market I suspect is somewhat cost sensitive. I think you might find more acceptance in the 250 to 350 HP range. It may be you already have plans for HP growth with the initial design. If not I would certainly consider options for more power as you test.

Thank you for the support. There has been a lot of interest for a higher horsepower variant - after the Talon we actually plan on working towards a 300-350hp engine!
 
A planned portfolio gap in the 200 - 300 SHP range? Seems strange from the outside looking in unless you're planning on going after the certified market. Can you get get us smarter on you reasoning/market approach? Much thanks.
 
A planned portfolio gap in the 200 - 300 SHP range? Seems strange from the outside looking in unless you're planning on going after the certified market. Can you get get us smarter on you reasoning/market approach? Much thanks.

Easy to de-rate or flat rate a turboprop to lower power levels as most certified ones are.

Trying to certify this would almost certainly sink the company and open you to much higher liability.
 
Easy to de-rate or flat rate a turboprop to lower power levels as most certified ones are.

Trying to certify this would almost certainly sink the company and open you to much higher liability.

Aware of the this common approach but 50% (max limit-limit) is huge; though, it would last forever at that point of rating if maintenance limits are hours based versus starts based.
 
The thermodynamic rating of some modern large frame PT6s are about double the flat rating in fact. This allows components sized for better efficiency at altitude though you pay a price down low.

On something designed for RVs which will usually be operated below oxygen altitudes, there would be a tradeoff in that approach.
 
Last edited:
That kinda assumes most /all operating conditions remain ~ the same. Not knowing the particulars here but in general: For a given set of conditions, operating at a de-rated setpoint is going to have an efficiency hit. Likewise increased firing temps will not only boost output but some efficiency gains are common; this to the detriment of parts life obviously.

Maybe Turbaero will weigh in on their portfolio approach. A planned uprating of the Talon some time after validation (a common approach)? A derating/uprating of the future product to close the portfolio gap/expand the top of their offering envelope?

Would be interesting to hear. I appreciate their efforts and am rooting for their success.
 
That kinda assumes most /all operating conditions remain ~ the same. Not knowing the particulars here but in general: For a given set of conditions, operating at a de-rated setpoint is going to have an efficiency hit. Likewise increased firing temps will not only boost output but some efficiency gains are common; this to the detriment of parts life obviously.

Maybe Turbaero will weigh in on their portfolio approach. A planned uprating of the Talon some time after validation (a common approach)? A derating/uprating of the future product to close the portfolio gap/expand the top of their offering envelope?

Would be interesting to hear. I appreciate their efforts and am rooting for their success.

I too am rooting for them. This is a most interesting and challenging engineering project for a small team.

The big engine, de-rated, pays a weight and cost penalty for sure and depending on altitude and power required may show an efficiency loss, somewhat offset by potentially less clearance leakage on the turbine and higher compressor pressures ratios with the physically larger components. Life could be extended with lower temps but that's probably of less concern here than in commercial applications.

Increasing the Talon engine output by this much would be quite challenging from a compressor mass flow/ efficiency standpoint, likewise with the turbine section and TIT limits.

Anyway, Step 1 is to get the smaller Talon built and into the testing phase to see how it performs before worrying much about a higher hp version. I hope Dave and team will show us some test stand running vids soon. :cool:
 
Last edited:
.
……Increasing the Talon engine output by this much would be quite challenging from a compressor mass flow/ efficiency standpoint, likewise with the turbine section and TIT limits…..
.
Sorry. Wasn’t clear as usual. I meant their smaller frame uprating to close a little of the portfolio gap. 10-12% after validation isn’t uncommon. Now a SHP of 225-ish starts to get very interesting. More available HP than a NA six cylinder at altitude and the up front cost delta is even more tantalizing when compared to the even more expensive 540s and 550s. Just sayin’

More info from the respective Mother Ship would be interesting.
 
Sorry. Wasn’t clear as usual. I meant their smaller frame uprating to close a little of the portfolio gap. 10-12% after validation isn’t uncommon. Now a SHP of 225-ish starts to get very interesting. More available HP than a NA six cylinder at altitude and the up front cost delta is even more tantalizing when compared to the even more expensive 540s and 550s. Just sayin’

More info from the respective Mother Ship would be interesting.

Sorry, I misunderstood. Agreed this could open up more possibilities to re-engine big four or small six cylinder powered aircraft, though without flat rating, hp at altitude wouldn't be much different than an atmo piston engine.

SFCs improve more at altitude on turbines though and that's attractive.
 
Hi Freemasm,

We (theoretically) have a little bit up our sleeve in relation to take-off power on our TA200TP. That is why we indicate that at this stage in our development program, it will be flat rated to 200hp to around 8,000'. However, the de-rating for take-off leaves a bit up our sleeve in case the actual performance does not match predicted performance. The de-rating also means that the engine is running conservative temperatures down low where a fair bit of operation is likely to take place. This will help with longevity and reliability.

In the interests of transparency, we have found that we have needed to tweak the design of the recuperator. The reason for this was around the calculated fatigue life of the most recent design not meeting our targets. Calculated performance was meeting our targets but structurally, some minor design changes are needed. The problem with structural tweaks is that in general, those structural tweaks affect the performance of the recuperator. Even small performance changes in the recuperator affect the other components, most notably the combustor. We have placed the fabrication of our compressor, turbines and combustor on temporary hold while the design of the recuperator is not only tweaked to achieve the performance and life targets, but also to fabricate and test the recuperator to assess actual performance and fatigue against the theoretical numbers. Once we have this data, then we can finalise the design of the remaining components with the confidence that all components are matched, for both the design point and for all off-design points within the operating envelope for the engine.

Being able to meet all the off-design requirements has made this design process extremely challenging. Wide operating temperature, altitude, speed, power etc. ranges, combined with the need for the ability to restart the engine should the flame go out for any reason make the whole design process a very complex juggling act.

While we are undertaking the fabrication and testing of the recuperator which is an activity that will take a fair while, our engineers will not be idle. They will be undertaking activities that will minimise the time to get the engine on the test stand, and also, will facilitate component testing of other components of the engine. All these activities will maximise the chances of a successful first run of the engine.

Our aim is to get the first engine into the (experimental) market where the benefits of such an engine can be proven, along with being able to prove that TurbAero will be a company that will provide exemplary product support.

As for the next product, a 300-350hp engine will be quite scalable from our 200hp variant, and there has proven to be a great deal of interest for an engine in this power range, particularly from the certificated market. As for certification, this will only be done in conjunction and with the support of a certificated aircraft manufacturer. We are not of the risk-taking mindset of build it and they will come. We need a definite market before taking on such an undertaking.

As has been alluded to, we need to walk before we can run. Our sole and primary focus at this stage is to get the 200hp engine on the test stand as soon as we can and complete its development to allow its delivery to customers as a safe and reliable product. Having been on this program for almost 5 years now, I need to say that we still have a lot of work ahead of us. What I am pleased to say is that we are making progress. To those outside watching, it may not appear to be so, but knowing how technical this program is and seeing what is being achieved and what problems are being resolved, I know that we are making progress.

On the topic of engine efficiency, our performance calculations indicate that the engine will be around 7% more efficient for the same power when operated at 10,000' rather than 5,000'; and 14% more efficient when operating at 20,000' rather than 10,000'. So, if you can get up high above 10,000', your fuel flows will look encouraging.

Dave
 
With the price of Lycomings increasing by leaps and bounds over the last few years, turbines and engines like the Adept V6 may actually start to fit into similar pricing structures soon...

roughly, what is the price target here? is it the same as a lycoming solution? 50% more? 100% more?

one of the problems of new engines is that the optimal pricing would not to have them be very profitable in the beginning, but to build market share and dealer/maintenance network. once they have good market share, the engines become cash cows for a very long time. (see Lycoming, for example.) but few engine builders have this sort of funding.
 
Much thanks for the insight, Sir. Another great example of how hard the design process is and the trade-offs required, even for a single component; e.g. robust structures/materials don't make for efficient heat transfer.

Best of luck. I'm always rooting for the new guys, market disrupters, and similar.
 
Thanks Dave for your update and usual clear reasoning on the various topics under discussion.

Freemasm: I think as prices exceed that of a comparable Lycoming engine, your market progressively shrinks. At 50% more it's tiny. At 100% more, miniscule to the point of the impossibility of ROI.

As development draws out in time, R&D costs continue to accumulate and unit price continues to climb. We've seen this on Deltahawk and Adept. At some point, they become non-viable to most buyers in the Experimental world.

Certification attempts almost always end badly with insufficient funding and Dave knows this. A well heeled partner is must. Mistral and Orenda are typical examples.

One also has to be aware of competitors which are ahead of you in the development cycle. Those first to market have a chance to gain major market share which becomes harder to compete with for the latecomers.

It's a tough nut to crack.
 
the price may be viable, even though it is higher (presumably longer time to overhaul compensates a little, too) --- but only if it is clear that the turbine is in it for the long haul. that means very well funded and expansive parts availability in the field, too. if people also fear that the company could go under, I don't think there will be a lot of uptake. nothing worse than an engine without spare parts.

and I would really like to see this one succeed. I hate riding a lawnmower engine's vibrations...
 
Answer to your question was in the first post of this thread and can be found here:
https://turb.aero/community/resources/two-most-commonly-asked-questions

and is 80-85k$.

200hp YIO-360-A1B6 is now 54k$ with Van's discount... .

Oliver

I just got quoted from a lycoming dealer for a brand new IO-360-M1B, I mean factory new with new parts/metal…96k without the core and a year wait. So it is VERY comparable with a piston engine if you compare apples to apples. You are not buying factory reman or factory overhaul for that jet.

Fun fact, I had to specifically request brand new pricing, he said they don’t even quote it because it is so astronomical and most people don’t even bother buying it.
 
Last edited:
I just got quoted from a lycoming dealer for a brand new IO-360-M1B, I mean factory new with new parts/metal…96k without the core and a year wait. So it is VERY comparable with a piston engine if you compare apples to apples. You are not buying factory reman or factory overhaul for that jet.

Fun fact, I had to specifically request brand new pricing, he said they don’t even quote it because it is so astronomical and most people don’t even bother buying it.
I called a couple engine vendors recently to see lead time, what they suggest, and price. Two very reputable vendors were at less than half that cost and one had engines he could put together immediately.
 
Back
Top