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That's pretty good and will be a game changer in the market if the numbers prove out in flight testing.
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But
But at what price point?
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Looks like they're aiming for Lyc 360 type pricing. We'll see how that ends up when they come to market.
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We will see
That is a pretty tall order. I hope they can achieve it...
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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. |
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 |
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...
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"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 |
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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. |
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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. |
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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... ;) |
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...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: |
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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? |
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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. |
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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. |
Thanks Dave. That's a good plan and clears up my question.
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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. |
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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 |
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.
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Paul |
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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. |
...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... |
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. ;) |
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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 |
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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 |
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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 |
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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 |
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. |
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. |
Most turbines use a combined starter/generator.
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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! |
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.
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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. |
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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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