|
-
POSTING RULES

-
Donate yearly (please).
-
Advertise in here!
-
Today's Posts
|
Insert Pics
|

02-07-2019, 01:15 PM
|
|
|
|
Join Date: Sep 2014
Location: Maple Valley, WA
Posts: 273
|
|
Quote:
Originally Posted by breister
Big weakness of turbines is that efficiency usually goes way down below 85% power or so, so pulling back the throttle doesn't really save that much and two 120s would be running at just about optimum producing 200hp continuous at 10k'.
|
Agreed... However, I find it interesting that Velocity doesn't truly publish a Vne speed for their aircraft. Instead their flight test includes a bit of flutter testing to help establish a Vne for each aircraft.
While they have "limited" to 200 kts historically, the airframe might actually be able to take advantage of the additional thrust available through a turbine engine. No one will really know until it's done.
Of course, Vmc will probably creep up to be a real thing for the airframe instead.
|

02-08-2019, 10:19 AM
|
 |
|
|
Join Date: Sep 2014
Location: Alameda, CA
Posts: 191
|
|
I'd love to put a turbine in the 14A I'm building. For me its just about the safety.
The W&B issues is what kills it for me. I don't want to have a special cowling an extra 2' long while my nose gear sits on the firewall. Whatever the engine mount is will have to have a place for the nose gear?
Although you could just mount the engine as close the normal length as possible so you can use the stock cowling and have a 1/2" steel firewall to make up the weight. 
__________________
-------------------
Dues paid (2020)
RV-14 #140394
Empennage - done(ish)
Wings - done(ish)
Fuselage - done(ish)
Finishing Kit - Somewhere in there
YouTube Build Channel
|

02-08-2019, 01:30 PM
|
|
|
|
Join Date: Dec 2011
Location: Alpharetta, Ga
Posts: 212
|
|
Quote:
Originally Posted by kiljoy
I'd love to put a turbine in the 14A I'm building. For me its just about the safety.
The W&B issues is what kills it for me. I don't want to have a special cowling an extra 2' long while my nose gear sits on the firewall. Whatever the engine mount is will have to have a place for the nose gear?
Although you could just mount the engine as close the normal length as possible so you can use the stock cowling and have a 1/2" steel firewall to make up the weight. 
|
You could add a parachute system forward of the firewall. That should add 100 lbs or so.
|

02-17-2019, 07:45 PM
|
|
|
|
Join Date: Aug 2018
Location: Adelaide, South Australia
Posts: 37
|
|
Turbine Aeronautics update
Hello to all readers again.
With some recent discussion on this thread, I thought it would be a timely moment to update folks on progress.
I'd like to start by saying that the development of a turbine engine is a major undertaking in many respects, particularly for one that offers the performance and features that we feel are necessary to be successful in the market.
The technical challenges that must be resolved are not to be considered lightly. We are incorporating some innovative technical features into our engines to ensure that they meet the fuel efficiency and reliability expectations of the kit aircraft builder. As standalone components, the design of these components is challenging. When combined with the other engine components, the challenges are more demanding because the performance of one component affects the performance of other components. What this means is that a lot of the design process is iterative. For example, whenever we modify the recuperator design, we must redesign the aero components (compressor, turbines etc.), which means that when the recuperator designer tweaks the recuperator, the results need to go to the aero designer to tweak the aero components, and those results need to then go back to the recuperator designer for him to re-tweak etc. This is just an example of the many iterative processes that need to be done to ensure that all our components achieve the correct design parameters, when combined into the final design.
This iterative process, combined with the technical complexity of the design of the many components has resulted in a shift to the right in our original timeline. Fortunately, the shift isn't too far to the right and we are very pleased with the progress on our program.
We are currently in the detailed design phase for many of our components. The good news from the work done to date is that our performance targets are still on-track. >200hp for a sea level takeoff on an ISA day; 180hp at 10,000' ISA conditions 180ktas should yield a Specific Fuel Consumption of marginally under 0.50 lbs/hp/hr and it is looking like this SFC may be achieved down to 150hp, same conditions. We are still on track for the engine to offer around 140hp at 20,000'.
Our Arion Lightning testbed aircraft has been built and will shortly be shipped to Australia for installation of the first airborne test unit, when it becomes available. We plan for this to be in around 12-15 months time from now.
We remain committed to bringing our engines to our primary market, being the recreational aircraft market. This is our sole focus and will remain so until we deliver our engines to the builders like you and me. My personal Lightning Bug and White Lightning projects are just waiting for the 200hp engine. As such, I think I am more motivated than anyone to see the availability of these engines!
For Tom at TSFlightlines, specific details about our fuel delivery system should be available within the next 3 months. I will get them to you asap. I spoke with your RV14 builder this morning to update him on progress.
For MercFE, the guys at Velocity are watching our progress with interest and we remain engaged with them.
Dave
|

02-17-2019, 09:15 PM
|
 |
|
|
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
|
|
.5 BSFC will be very impressive at this scale if you can do that and that accomplishment would go a long ways towards wider acceptance of the engine in this market.
|

02-17-2019, 09:26 PM
|
|
|
|
Join Date: Aug 2018
Location: Adelaide, South Australia
Posts: 37
|
|
Quote:
Originally Posted by rv6ejguy
.5 BSFC will be very impressive at this scale if you can do that and that accomplishment would go a long ways towards wider acceptance of the engine in this market.
|
That is for sure Ross.
We were not prepared to proceed with the development program if we couldn't get the SFC to less than 0.55 lbs/hp/hr so that was our initial target. Indications are that we can do a little better than our target, but time will tell. In 10 months when its on the test stand and we have verifiable numbers, that will be crunch time for us.
If we can demonstrate that level of performance, we hope that we can convert the LyConti customers to turbine power.
|

02-20-2019, 02:53 PM
|
|
|
|
Join Date: Dec 2006
Location: Atlanta, GA
Posts: 1,231
|
|
Quote:
Originally Posted by MercFE
Agreed... However, I find it interesting that Velocity doesn't truly publish a Vne speed for their aircraft. Instead their flight test includes a bit of flutter testing to help establish a Vne for each aircraft.
While they have "limited" to 200 kts historically, the airframe might actually be able to take advantage of the additional thrust available through a turbine engine. No one will really know until it's done.
Of course, Vmc will probably creep up to be a real thing for the airframe instead.
|
Well they are fixin' to find out whether the air frame can "handle it" in any case. As of last summer they are building a series of twin aircraft using the 240hp Velka Bites turbines (not as efficient as the 200hp Turbine Aeronautics as they do not include the re-generators) for a foreign customer. While they may not be used routinely for speed runs (I think they are meant as short range ferry aircraft from lower airports up to mountain towns, avoiding many driving hours on tortuous roads), you can bet someone will "open it up to see how fast it goes."
Typically "plastic planes" are less susceptible to flutter than aluminum, I think it has to do with dampening due to elasticity - but nothing is "safe" until proven so. Absent a flutter issue, there's no real reason you couldn't drive a Velocity upwards of 300KIAS if you have enough horsepower. They are really rather tough in the +/- g's department and should handle turbulence well also.
|

02-20-2019, 02:58 PM
|
|
|
|
Join Date: Dec 2006
Location: Atlanta, GA
Posts: 1,231
|
|
Quote:
Originally Posted by Turbine Aeronautics
That is for sure Ross.
We were not prepared to proceed with the development program if we couldn't get the SFC to less than 0.55 lbs/hp/hr so that was our initial target. Indications are that we can do a little better than our target, but time will tell. In 10 months when its on the test stand and we have verifiable numbers, that will be crunch time for us.
If we can demonstrate that level of performance, we hope that we can convert the LyConti customers to turbine power.
|
No doubt. Saving 100 lbs on the engine provides a weight allowance of 15 more gallons of fuel - which should make up the range difference of the SFC penalty. I'm sure people will be especially anxious to hear test results using auto or farm diesel, perhaps with appropriate additives, to avoid the expense of Jet A.
|

02-20-2019, 05:10 PM
|
|
|
|
Join Date: Aug 2018
Location: Adelaide, South Australia
Posts: 37
|
|
Quote:
Originally Posted by breister
No doubt. Saving 100 lbs on the engine provides a weight allowance of 15 more gallons of fuel - which should make up the range difference of the SFC penalty. I'm sure people will be especially anxious to hear test results using auto or farm diesel, perhaps with appropriate additives, to avoid the expense of Jet A.
|
There will not be a significant difference in fuel flows between our 200hp engine at 150hp/10,000' compared to the equivalent 200hp piston engines at 150hp/10,000'. In fact, they should be very similar. However, our 200hp engine is being optimised for a 180hp cruise at 10,000' which is a power the piston engines generally will not achieve (unless augmented).
We are also hoping to save well more than 100lbs of weight over the piston engine competition.
We will advise the public of our test results with pump diesel in due course. We believe that we have an additive solution to resolve blockage of injectors, but this will all be tested in due course.
|

03-01-2019, 11:40 AM
|
|
|
|
Join Date: Dec 2006
Location: Atlanta, GA
Posts: 1,231
|
|
Quote:
Originally Posted by RV8JD
Not necessarily. It depends on the orientation of the layups/plies, and in the end, the relationship between the bending stiffness and torsional stiffness of the surface. The structural damping inherent in a built-up aluminum structure versus a composite structure may or may not be significantly different.
Composite structures can have better flutter margins if the layups/plies are tailored to maximize torsional stiffness while minimizing bending stiffness, within the constraints of other structural requirements (e.g, bending strength). The bending and torsional stiffnesses can also be somewhat tailored in metal structures to improve flutter margins, but not nearly to the extent of composite structures, as easily, or without adding a bunch of weight.
|
All good points. I'm no structural engineer. I did learn once that the manufacturer of my fiberglass plane stipulated Vne in terms of IAS, not TAS as Van has done for his planes. Apparently they felt nobody would fly them high enough to get close to mach...
|
| Thread Tools |
Search this Thread |
|
|
|
| Display Modes |
Linear Mode
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT -6. The time now is 02:43 AM.
|