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  #101  
Old 03-05-2019, 12:56 AM
Turbine Aeronautics Turbine Aeronautics is offline
 
Join Date: Aug 2018
Location: Adelaide, South Australia
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Quote:
Originally Posted by rv6ejguy View Post
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.
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  #102  
Old 03-05-2019, 04:39 AM
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rv6ejguy rv6ejguy is offline
 
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Thanks Dave. That's a good plan and clears up my question.
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Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 441.0 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
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  #103  
Old 03-05-2019, 05:30 AM
Mudfly Mudfly is offline
 
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Location: Alpharetta, Ga
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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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Last edited by Mudfly : 03-05-2019 at 05:36 AM.
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  #104  
Old 03-05-2019, 10:49 AM
Canadian_JOY Canadian_JOY is offline
 
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Location: Ontario, Canada
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Quote:
Originally Posted by Turbine Aeronautics View Post
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!
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  #105  
Old 03-05-2019, 11:06 AM
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rv6ejguy rv6ejguy is offline
 
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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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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 441.0 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm


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  #106  
Old 03-05-2019, 01:49 PM
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Ironflight Ironflight is offline
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Quote:
Originally Posted by Canadian_JOY View Post
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!
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
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  #107  
Old 03-06-2019, 02:10 PM
breister breister is offline
 
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Quote:
Originally Posted by rocketman1988 View Post
...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"
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.

Last edited by breister : 03-06-2019 at 02:22 PM.
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  #108  
Old 03-06-2019, 04:37 PM
rocketman1988 rocketman1988 is offline
 
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...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...
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  #109  
Old 03-06-2019, 04:51 PM
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rv6ejguy rv6ejguy is offline
 
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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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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 441.0 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm


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  #110  
Old 03-06-2019, 05:41 PM
Turbine Aeronautics Turbine Aeronautics is offline
 
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Location: Adelaide, South Australia
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Quote:
Originally Posted by Canadian_JOY View Post
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!
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
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