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-   -   Turbine Aeronautics (https://vansairforce.net/community/showthread.php?t=148635)

rv6ejguy 03-03-2019 10:18 AM

That's pretty good and will be a game changer in the market if the numbers prove out in flight testing.

rocketman1988 03-03-2019 01:41 PM

But
 
But at what price point?

rv6ejguy 03-03-2019 02:09 PM

Looks like they're aiming for Lyc 360 type pricing. We'll see how that ends up when they come to market.

blueflyer 03-03-2019 02:35 PM

Quote:

Originally Posted by rv6ejguy (Post 1328911)
Looks like they're aiming for Lyc 360 type pricing. We'll see how that ends up when they come to market.

that would be really enticing.

rocketman1988 03-03-2019 03:21 PM

We will see
 
That is a pretty tall order. I hope they can achieve it...

Timberwolf 03-03-2019 04:09 PM

They would be the first to achieve such a low price point for a new engine with that capability. The helo guys have been buying T-62's and variants for a while at low prices, but nothing comes close until you step up to a PT6A-20 which can be had ~$80k. Though that exceed the HP we would need on an RV I thought long and hard about it for one of my projects. However the 32 gal/hr at cruise figure well exceeded the practicality of such.

Would really love to see this engine work out.

Turbine Aeronautics 03-04-2019 04:38 AM

Updated estimations following the most recent design work have the price point in the region of $50k so we are now above the new IO360 in purchase cost. That is more than we would have liked but given the benefits of such an engine, we believe it still represents good value.

The minimal routine maintenance and the projected longer TBO, combined with the lower projected cost of overhaul should result in a lower hourly cost to run the engine than the LyConti?s. And then there are the (in general) cheaper fuels...

Dave

rocketman1988 03-04-2019 05:37 AM

Good
 
I really hope you can keep it in that ballpark...it would certainly make a nice alternative to the 50+year old, $50k+ engines we are stuck with now...

rv6ejguy 03-04-2019 06:16 AM

Quote:

Originally Posted by Turbine Aeronautics (Post 1329027)
Updated estimations following the most recent design work have the price point in the region of $50k so we are now above the new IO360 in purchase cost. That is more than we would have liked but given the benefits of such an engine, we believe it still represents good value.

The minimal routine maintenance and the projected longer TBO, combined with the lower projected cost of overhaul should result in a lower hourly cost to run the engine than the LyConti?s. And then there are the (in general) cheaper fuels...

Dave

Valid points however it's really best not to project TBOs before even a single example has gone that many hours running in the real world...

breister 03-04-2019 11:41 AM

Quote:

Originally Posted by rv6ejguy (Post 1328501)
I don't think you'll see a non-flat rated 200hp turbine produce 150 hp at 17,500 feet. Turbo normalize the Lycs and you'd get some good speeds and fuel flows running LOP.

I started with this:

"However, our 200hp engine is being optimised for a 180hp cruise at 10,000'"

I guesstimated 150hp up to about 15,000', with normal lapse rate thereafter. As I said, my napkin math may be far off!

A turbine is not exactly like turbonormalized piston, but as you pointed out they are generally flat rated (due to heat in the hot section) up to some altitude and then lapse the same as a normally aspirated. TA is saying they still generate 180hp @ 10,000', so 150hp per engine @ 15,000' is not a bad guess, and incidentally is the same horsepower as two normally aspirated IO 360 200 hp motors @ 75% power. With two engines, that is 300hp@15k'; normal lapse should drop you down to ~65% power @ FL250. You are looking at less horsepower but also less induced drag as you get closer to L/D (max) so IAS should drop slightly but TAS should continue to increase a bit. The general formula usually applies until you approach high Mach numbers, when induced drag begins to rise despite low IAS.

Again the caveats - my recollections are 35 years old, and this ain't no Phantom! :D

breister 03-04-2019 11:44 AM

Quote:

Originally Posted by rocketman1988 (Post 1328533)
"... And then of course, if you just add a small bleed air port, you could add pressurization..."

I know it was kind of TIC but there is substantially more to the design of a reliable, safe pressurized airplane than "just adding a small bleed air port"...

Not to mention weight. Shhh, we're having fun... ;)

Seriously though, if someone comes through with the right engine, someone else will undoubtedly try pressurization. Probably not me, at least not in my current plane, and probably never as I'm getting old.

breister 03-04-2019 11:54 AM

Quote:

Originally Posted by Turbine Aeronautics (Post 1328806)
For your interest, our current predictions (subject to validation once the engine is running of course) at 20,000? give a maximum continuous cruise power of 138hp with a fuel flow of around 9.8 usg per hour at a 180ktas cruise state, ISA conditions.

We don?t intend to offer a bleed port initially. We figure that not a high % of our customers will be pressurising their aircraft. Indeed, we optimised the engine for 10,000? because we feel that not many will likely go much higher. We suspect that 18,000? will be many folks limit where cannula oxy can be used and pressurisation is not a necessity. 140hp or thereabouts is still a fairly useful power at 18,000?.

Dave

Thanks Dave. Interesting, 138hp @ FL200 is less of a lapse rate than a normally aspirated piston for a 10,000' altitude difference, I would think you might start running into turbine over speed to get sufficient compression?

And yes, most of the fleet is not pressurized and old girlfriends won't want to wear the mask. I don't recall which air frame you are quoting, but my current air frame would scoot considerably faster than 180ktas on 140hp @ 18,000'. A twin Velocity, if their ad is to be believed, should be very close to 210IAS with that horsepower which would be over 335ktas @FL200. I think my math is wrong on that, using 3% / 1,000' increase in TAS for the same IAS? There is probably some penalty for prop inefficiency up higher I'm not including.

rv6ejguy 03-04-2019 01:29 PM

Quote:

Originally Posted by breister (Post 1329124)
I started with this:

"However, our 200hp engine is being optimised for a 180hp cruise at 10,000'"

I guesstimated 150hp up to about 15,000', with normal lapse rate thereafter. As I said, my napkin math may be far off!

A turbine is not exactly like turbonormalized piston, but as you pointed out they are generally flat rated (due to heat in the hot section) up to some altitude and then lapse the same as a normally aspirated. TA is saying they still generate 180hp @ 10,000', so 150hp per engine @ 15,000' is not a bad guess, and incidentally is the same horsepower as two normally aspirated IO 360 200 hp motors @ 75% power. With two engines, that is 300hp@15k'; normal lapse should drop you down to ~65% power @ FL250. You are looking at less horsepower but also less induced drag as you get closer to L/D (max) so IAS should drop slightly but TAS should continue to increase a bit. The general formula usually applies until you approach high Mach numbers, when induced drag begins to rise despite low IAS.

Again the caveats - my recollections are 35 years old, and this ain't no Phantom! :D

138 isn't far off 150 if it will do it so your calc was pretty close. Plenty to prove at altitude as far as compressor surge margins, relights up there, turbine inlet temps etc.

breister 03-04-2019 02:57 PM

Quote:

Originally Posted by Turbine Aeronautics (Post 1328806)
We don?t intend to offer a bleed port initially.

Almost forgot, the bleed port is not just about pressurization.

It's about free air conditioning and easy heating.

All you need is an inter-cooler, a water separator, and an expansion valve. Lightweight, can fit under almost any cowling.

BIG opportunity for a selling point, especially if you cobbled together a kit for people... :D

If you make it standard, but ship it capped, it would preclude needing a separate design.

Of course, you could probably charge a premium for the feature too. It's not drilling the hole that is expensive, it's knowing where to drill... ;)

airguy 03-04-2019 04:00 PM

Quote:

Originally Posted by breister (Post 1329175)
Almost forgot, the bleed port is not just about pressurization.

It's about free air conditioning and easy heating.

All you need is an inter-cooler, a water separator, and an expansion valve. Lightweight, can fit under almost any cowling.

BIG opportunity for a selling point, especially if you cobbled together a kit for people... :D

If you make it standard, but ship it capped, it would preclude needing a separate design.

Of course, you could probably charge a premium for the feature too. It's not drilling the hole that is expensive, it's knowing where to drill... ;)

That would be especially handy for people that are planning on cruising at high altitude to take advantage of the engines efficiency up there - and no longer have a source of cabin heat from an exhaust heat muff.

rocketman1988 03-04-2019 04:28 PM

...and
 
...and, as always, the devil is in the details.

What do you think happens when you start siphoning off bleed air?

Let me give you a hint:

TANSTAAFL

"There Ain't No Such Thing As A Free Lunch":rolleyes:

rv6ejguy 03-04-2019 05:28 PM

Quote:

Originally Posted by rocketman1988 (Post 1329194)
...and, as always, the devil is in the details.

What do you think happens when you start siphoning off bleed air?

Let me give you a hint:

TANSTAAFL

"There Ain't No Such Thing As A Free Lunch":rolleyes:

Sometimes it's beneficial to bleed compressor air at altitude to stay out of the surge region. Cabin air volume requirements are generally pretty low compared to the core engine mass flow. It's intriguing to contemplate the possibilities for simple heat and a/c.

rv6ejguy 03-04-2019 07:59 PM

Dave,

Is there some reason your engine design suffers less power loss with altitude than PWC engines? Some test data on these shows variously 37-47% loss in shp at 17,500 feet depending on model and TAS. You're saying only a 31% loss in power.

I understand the recuperator improves the SFC at the expense of a loss in hp.

Is the thermodynamic rating of your engine higher than 200 shp at sea level/ standard day conditions?

Turbine Aeronautics 03-05-2019 12:40 AM

Quote:

Originally Posted by rocketman1988 (Post 1329194)
...and, as always, the devil is in the details.

What do you think happens when you start siphoning off bleed air?

Let me give you a hint:

TANSTAAFL

"There Ain't No Such Thing As A Free Lunch":rolleyes:

You are spot on there Bob!

We want to make this engine as affordable as possible which means that at least initially, some non-essential features such as bleed air which comes at a cost, will not be designed into the engine. Most of our customers will be operating below 10,000?, most of the time. It is for this large group that we need to make it affordable for.

If we subsequently offer an engine with a bleed port, that will come at at the expense of increased cost due to different turbomachinery, different architecture etc.

Turbine Aeronautics 03-05-2019 12:42 AM

Quote:

Originally Posted by rv6ejguy (Post 1329039)
Valid points however it's really best not to project TBOs before even a single example has gone that many hours running in the real world...

I agree Ross. A large amount of testing will determine this parameter. We have our target, but real life testing will ultimately determine the recommended TBO.

Turbine Aeronautics 03-05-2019 12:56 AM

Quote:

Originally Posted by rv6ejguy (Post 1329253)
Dave,

Is the thermodynamic rating of your engine higher than 200 shp at sea level/ standard day conditions?

You are correct Ross. On an ISA sea level day, 200hp will be achieved at well below the TIT and rpm limits. If we allowed the engine to operate to its TIT limit, we could offer significantly more than 200hp at sea level.

We would like the engine to initially be operated conservatively to ensure reliability and longevity, particularly while the engine builds up a safe history of operation in the field. We will run some test engines at a higher takeoff power, but will not let our regular customers do so. If our test engines demonstrate reliability and longevity at a higher takeoff power, we would likely offer a reprogram of the ECU to our customers to allow them to access that power.

rv6ejguy 03-05-2019 04:39 AM

Thanks Dave. That's a good plan and clears up my question.

Mudfly 03-05-2019 05:30 AM

Thanks
 
Thanks Dave for the information! Good idea keeping it simple initially. People hear "turbine" and they start thinking faster and higher. Like you said, maybe later on that stuff. Right now we just need a simple, reliable, affordable engine that doesn't burn AVGAS. Sorry, that AVGAS part is my own little pet peeve:).
Someone has to take the first step, otherwise we just keep kicking the can down the road.
Still a few moths away, but any plans to attend Oshkosh this year? No large booth required. Maybe just a couple lawn chairs and an umbrella so those of us that are interested might sit down and chat.

Canadian_JOY 03-05-2019 10:49 AM

Quote:

Originally Posted by Turbine Aeronautics (Post 1329283)
You are spot on there Bob!

We want to make this engine as affordable as possible which means that at least initially, some non-essential features such as bleed air which comes at a cost, will not be designed into the engine. Most of our customers will be operating below 10,000?, most of the time. It is for this large group that we need to make it affordable for.

If we subsequently offer an engine with a bleed port, that will come at at the expense of increased cost due to different turbomachinery, different architecture etc.

Please forgive this most basic of questions... Without bleed air, how would one keep the cabin warm at altitude, or, more particularly, for at least six months of the year where, here in Canada, we have this very real phenomenon called "winter"?

All of my turbine experience has involved bleed air use so I'm struggling to figure how how an engine without bleed air is going to keep the cabin warm. Please don't suggest a Janitrol heater! :eek::D

rv6ejguy 03-05-2019 11:06 AM

Ducting air from the oil cooler would work or ducting exhaust through a HX. Bleed air would be easier to hook up and I hope Dave considers that for his Northern based customers.

Ironflight 03-05-2019 01:49 PM

Quote:

Originally Posted by Canadian_JOY (Post 1329390)
Please forgive this most basic of questions... Without bleed air, how would one keep the cabin warm at altitude, or, more particularly, for at least six months of the year where, here in Canada, we have this very real phenomenon called "winter"?

All of my turbine experience has involved bleed air use so I'm struggling to figure how how an engine without bleed air is going to keep the cabin warm. Please don't suggest a Janitrol heater! :eek::D

In the Subsonex, we used a heated seat - and I have a heated vest (with its own battery) for core heat. But I am not living in Canadian latitudes!

Paul

breister 03-06-2019 02:10 PM

Quote:

Originally Posted by rocketman1988 (Post 1329194)
...and, as always, the devil is in the details.

What do you think happens when you start siphoning off bleed air?

Let me give you a hint:

TANSTAAFL

"There Ain't No Such Thing As A Free Lunch":rolleyes:

That depends entirely on how much you siphon off.

Turbines pass a LOT of air! Enough air for AC or heating would be such a tiny fraction I cannot imagine it taking even 1%. Edit: I'm basing this on the assumption that the air is solely for heat / AC in an un-pressurized cockpit. Every function performed by bleed air increases the amount siphoned off, so if simple heat / AC takes 1% away from maximum power then pressurization might take another 1-5%, depending on how well the cabin is sealed and the altitude.

For AC, a small amount of compressed air passes through an inter-cooler still compressed (hot), thus cooling it. Then it enters an expansion chamber, which also serves to separate out any water, through a check valve which strictly limits how much total air "escapes" from the compressor. The water goes into a drip pan and a tiny pinhole allows it to drain slowly. Some even use a check valve and close the exit when there is no water. Finally the air is released into the cockpit at near-normal atmospheric pressure.

Bleed air satisfies the TANSSAAFL rule unless you are racing and need that extra 1% power.

rocketman1988 03-06-2019 04:37 PM

...and
 
...and you are basing that 1% on what?

I am quite familiar with ACMs but thanks for the basic review.

I would think that the engine manufacturer would have a pretty good idea of the bleed air losses. They have already stated that the engine is capable of more power, so the whole discussion may be moot.

My point is that it takes power to drive that ACM and that power comes from somewhere...TANSTAAFL...

rv6ejguy 03-06-2019 04:51 PM

May be easier for them to integrate a HX into the exhaust flow for cabin heat from the start if not easy to do off the oil cooler. Many folks will need some way to heat the cabin. Might as well factory engineer this detail rather than leaving it in the hands of the customer.

I offer to test it under real winter conditions up here and give them feedback. ;)

Turbine Aeronautics 03-06-2019 05:41 PM

Quote:

Originally Posted by Canadian_JOY (Post 1329390)
Please forgive this most basic of questions... Without bleed air, how would one keep the cabin warm at altitude, or, more particularly, for at least six months of the year where, here in Canada, we have this very real phenomenon called "winter"?

All of my turbine experience has involved bleed air use so I'm struggling to figure how how an engine without bleed air is going to keep the cabin warm. Please don't suggest a Janitrol heater! :eek::D

I guess the easy answer is that the cabin could be kept warm using the same type of system that all the RVs use now with the piston engines that are fitted. Our engine will have an oil cooler for the gearbox and also exhaust pipes. Those are two good sources of heat that do not detract from the performance of the engine or add complexity/cost (two features that we are trying to minimise to the greatest extent possible!).

Guys, please remember that even though we are incorporating some innovative technology into our engines, we won't sell any engines if they are not affordable. A bleed air source will reduce the fuel efficiency, add development cost, add complexity etc. For the sake of a heat muff around an exhaust pipe or hot air pickup at the back of the oil cooler (two simple and low cost/reliable options), we don't want to add big cost by making the engine itself more complicated.

Our philosophy is that we want to deliver an affordable, reliable and fuel efficient turbine engine to the market in order to make the technology as accessible as possible to as many folks as possible. We can up-feature later when we know that folks are prepared to pay an extra $X,000 for an engine.

Dave

Turbine Aeronautics 03-06-2019 05:46 PM

Quote:

Originally Posted by Mudfly (Post 1329311)
Thanks Dave for the information! Good idea keeping it simple initially. People hear "turbine" and they start thinking faster and higher. Like you said, maybe later on that stuff. Right now we just need a simple, reliable, affordable engine that doesn't burn AVGAS. Sorry, that AVGAS part is my own little pet peeve:).
Someone has to take the first step, otherwise we just keep kicking the can down the road.
Still a few moths away, but any plans to attend Oshkosh this year? No large booth required. Maybe just a couple lawn chairs and an umbrella so those of us that are interested might sit down and chat.

Hi Shawn,

Andrew and I will be at Oshkosh again this year. We will not have a booth (next year we plan to) and will be wandering the homebuilt flightline.

I shall check our schedule as the event approaches and see if we can offer a "lawn-chair" get together for those that want to meet us and ask questions. If we can organise it, I'll announce it on this thread so if anyone wants to turn up, they can do so.

Dave

Turbine Aeronautics 03-06-2019 05:53 PM

Quote:

Originally Posted by rocketman1988 (Post 1329721)
...and you are basing that 1% on what?

I am quite familiar with ACMs but thanks for the basic review.

I would think that the engine manufacturer would have a pretty good idea of the bleed air losses. They have already stated that the engine is capable of more power, so the whole discussion may be moot.

My point is that it takes power to drive that ACM and that power comes from somewhere...TANSTAAFL...

Thanks Bob. You are spot on again.

Ours is only a "baby" engine compared to whats out there now. Any bleed air that is tapped is going to hurt the overall engine performance and lead to a much more demanding performance requirement from the turbomachinery components. This then flows on to many other components and adds $$$$$.

Dave

Turbine Aeronautics 03-06-2019 06:00 PM

Quote:

Originally Posted by rv6ejguy (Post 1329728)
May be easier for them to integrate a HX into the exhaust flow for cabin heat from the start if not easy to do off the oil cooler. Many folks will need some way to heat the cabin. Might as well factory engineer this detail rather than leaving it in the hands of the customer.

I offer to test it under real winter conditions up here and give them feedback. ;)

Thanks for the testing offer Ross. That's very kind of you :D

We will be working with one of our early customers who will be installing his engine in an RV14. If he chooses to install a heating system, he might be able to offer his solution to his fellow RV (and other) brethren.

We also plan to work with a company to develop firewall forward packages for all popular experimentals that will cover both new-build and retrofits. I suspect that a heating system will be something that they will develop as an option for their packages.

Dave

rv6ejguy 03-06-2019 07:55 PM

Dave, always appreciate your candor. Gives your project and goals legitimacy unlike so many others in this field.

Wish you the best in this endeavour. An affordable, efficient turboprop is just a way cool concept that people have dreamed about for a long time.

hgerhardt 03-06-2019 10:38 PM

How do you intend to drive an alternator? Some sort of PTO shaft to drive a V-belt pulley? Or a spline drive PTO?

If that's the plan, you could use an automotive A/C compressor to build a heat pump which gives cooling and heating. Remember that to turn an A/C system into a heat pump, you only need a valve which reverses the refrigerant flow.

Actually, the more I think about this, you're going to need a spline drive pad for a prop governor anyway. Might as well have a 2nd one to drive the alternator and/or compressor. Robinson R44's use the spline drive that's normally used for rear-mounted governors to drive the A/C compressor with a V-belt adapter.

rv6ejguy 03-07-2019 04:57 AM

Most turbines use a combined starter/generator.

David Z 03-07-2019 08:36 AM

Bleed Air is not the direction technology is going. Aircraft like the Boeing 787 use independent compressors driven by the accessory gear box. Stealing bleed air from the engine is inefficient.

Depends on the size of the starter/generator, electrical heat could be an option too. Oil cooler for cabin heating is an interesting idea. I wonder if there is enough heat available for us cold Canucks. It is waste heat, might as well use it!

tswanson 03-07-2019 10:34 AM

Lawn Chair Discussion or Forum?
 
Lawn Chair Discussion? I'm not sure if or what they charge to host this, but you guys should see if you can get a forum slot. I'm sure lots of folks would be interested enough to sit down for an hour. Just my 2 cents.

David Z 03-07-2019 08:42 PM

I'm still years away from an engine, so this definitely excites me. The timing could work out quite well. I fly (transport category) turboprops for a living, and would love to have an affordable turboprop hot-rod as a personal plane too.

Things like cabin heat will be worked out, I'm not too worried about no bleed air option, there are other ways to get the heat.

Turbine Aeronautics 03-08-2019 04:39 PM

Quote:

Originally Posted by tswanson (Post 1329899)
Lawn Chair Discussion? I'm not sure if or what they charge to host this, but you guys should see if you can get a forum slot. I'm sure lots of folks would be interested enough to sit down for an hour. Just my 2 cents.

I?m considering a forum slot as we have a lot of interest on other aircraft type forums as well. I?ve contacted the EAA but am awaiting a response.

Worst case, I can probably just say I?ll be at xxx at xx pm on the Wednesday and we can have an informal gathering i.e. the lawn chair get together.

Dave


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