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 Post subject: Re: You say you want an Evolution ...
PostPosted: 21 Jul 2017, 10:38 
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From what I understand, this single event turns out to be the fault of the "builder" in that he choose to paint the aircraft black
What is the source of this speculation? I hadn't heard that the factory or NTSB has said anything about cause.

There is already a thread on this in Crash Talk. This discussion belongs there.

I heard the same thing as what John reported back at the Branson fly in where we talked about issues and solutions for the Evo.

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 Post subject: Re: You say you want an Evolution ...
PostPosted: 21 Jul 2017, 21:38 
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How would they deal with the joggle if applying the Villanger system?
The Villenger system is thin but it's not zero. It requires an insulating layer of fiberglass against the carbon, then the de-ice layer, then a covering layer of more glass to protect it, then paint. They build it up in the joggle and sand it to match the original design contour.

Pictures of the Villenger system on the inlet, showing the rough surface of the heating layer not yet covered in a glass layer, and of prop blades with the installation in process and finished.


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 Post subject: Re: You say you want an Evolution ...
PostPosted: 22 Jul 2017, 00:07 
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Username Protected wrote:
The airplane was originally designed to fly ~330+ ktas, so it would be a shock to me that the wing would only like 170 kias....Here is a spreadsheet given to me by Lancair on the performance of the -135A.
Thanks for that, I'd been looking for data like that. I used it to plot NM/gal vs. IAS. It's the powered version of a glider's drag polar, basically the inverse of the familiar curve of total drag = induced drag + profile drag
Attachment:
Evo MPG vs IAS.pdf
There's a lot of scatter but it's clear the peak of the curve is somewhere around 170 KIAS, as Austin said. At FL 280 that's about 270 KTAS. Not really a peak, the top of a drag polar is more of a rounded summit, pretty flat on top, so it doesn't cost you much range to go a little faster to stay on the front side of the curve where maintaining airspeed is easier. But the curve gets steeper the farther it gets from that summit so each additional knot costs progressively more. At FL 280, 330 KTAS is about 210 KIAS, about 40 kts faster than the summit.
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At any rate, there is no wrong choice. It's what is right for you. I just hope to be informative on my experiences with the Evo.
As do I! Couldn't have said it better myself.


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Last edited on 22 Jul 2017, 01:25, edited 1 time in total.

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 Post subject: Re: You say you want an Evolution ...
PostPosted: 22 Jul 2017, 01:13 
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Dave,

There is also TORQUE, ITT, Ng and Np in that excel sheet that Gerry uploaded. Columns are just shrunk and/or hidden.

Jon


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 Post subject: Re: You say you want an Evolution ...
PostPosted: 22 Jul 2017, 09:31 
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I must have used the incorrect standard OAT when I originally calculated speed at FL280 and 170 indicated. Did it again and it came out at 268 ktas instead of the 160 I did the first time. I would be curious to see if some of these planes have de-ice systems and if they effected the efficiency at higher speeds. Probably not, but with planes that can have a multitude of different configurations, it would be prudent to find out as much detail as we can as to how they are configured and what speed they are flying at most efficiently.


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 Post subject: Re: You say you want an Evolution ...
PostPosted: 22 Jul 2017, 09:42 
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Username Protected wrote:
Dave,

There is also TORQUE, ITT, Ng and Np in that excel sheet that Gerry uploaded. Columns are just shrunk and/or hidden.

Jon

Good spot! I didn't notice that myself. One thing I wonder is how the data in the spreadsheet deals with winds aloft. I noticed that most of the 10+ nm/gal data points are from the same airplane and he was running a VERY low ITT. As if he was loafing the plane and letting a big wind push him. It would be very hard to get accurate data without at least the indicated airspeed at that time. Which inconveniently, all four of those data points don't supply that information.


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 Post subject: Re: You say you want an Evolution ...
PostPosted: 22 Jul 2017, 09:53 
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Username Protected wrote:
There's a lot of scatter but it's clear the peak of the curve is somewhere around 170 KIAS, as Austin said. At FL 280 that's about 270 KTAS. Not really a peak, the top of a drag polar is more of a rounded summit, pretty flat on top, so it doesn't cost you much range to go a little faster to stay on the front side of the curve where maintaining airspeed is easier. But the curve gets steeper the farther it gets from that summit so each additional knot costs progressively more. At FL 280, 330 KTAS is about 210 KIAS, about 40 kts faster than the summit.

I took all of the data points that were closest to 170 IAS and averaged the data.

With 7 data points:

Average IAS: 171
Average NM/Gal: 8.5

NM/gal if I remove the one anomaly of 10.5 nm/gal: 8.2 nm/gal

As I said before, I see low 8's to high 7's for nm/gal going 310+ ktas (lowest typically 7.8 nm/gal). I don't see the inefficiency that Austin spoke of with the -42. Unless I'm looking at something incorrectly. A half a nm/gal or less penalty to fly 40+ kts faster to me seems worth it.


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 Post subject: Re: You say you want an Evolution ...
PostPosted: 22 Jul 2017, 10:32 
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Here's another oddity I noticed. I tried looking up the tail numbers listed for the data points because several of the tail numbers were similar and seemed odd.

Tail numbers:

5DW - Piper Turbo Arrow 4
5DWT - no flightaware data
7DW - 1951 DEHAVILLAND DHC-1 CHIPMUNK
7DWT - no flightaware data

I'm not sure what all of this means, but it's odd for sure.


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 Post subject: Re: You say you want an Evolution ...
PostPosted: 24 Jul 2017, 02:20 
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I took all of the data points that were closest to 170 IAS and averaged the data...Average IAS: 171, Average NM/Gal: 8.5....I see low 8's to high 7's for nm/gal going 310+ ktas
We don't know how they collected their data points so comparing them to your own, with differences in engine and possibly other things, may be apples to oranges. To get at the efficiency of the airframe, as Austin was saying, at higher airspeeds it's better to hold constant as many variables as possible by using their data. From eyeballing the chart, they show 210 KIAS as giving about 6 NM/Gal vs. the 8.5 NM/Gal at 170 KIAS, or 40% more fuel per mile. While a different engine will move that curve up or down its shape is a function of the airframe and shouldn't change so the proportional cost of going from 270 to 330 KTAS at FL 280 should be the same for you, about 40% greater fuel burn per mile.

Of course, turbine operating cost tends to be dominated not by fuel but by the hourly engine reserve for HSI and overhaul, and going 330 vs. 270 true will put almost 20% fewer hours on the engine, which offsets the extra fuel burn some. Will that be enough to pay for the extra fuel expense? Beats me, I haven't run the numbers. Apparently Austin didn't think so.


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 Post subject: Re: You say you want an Evolution ...
PostPosted: 24 Jul 2017, 02:26 
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Username Protected wrote:
Here's another oddity I noticed. I tried looking up the tail numbers listed for the data points because several of the tail numbers were similar and seemed odd.
Tail numbers:
5DW - Piper Turbo Arrow 4
5DWT - no flightaware data
7DW - 1951 DEHAVILLAND DHC-1 CHIPMUNK
7DWT - no flightaware data
I'm not sure what all of this means, but it's odd for sure.
That column is unlabeled, and they appear not to be tail numbers. I took them for abbreviations of some kind but I have no guess what they mean.


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 Post subject: Re: You say you want an Evolution ...
PostPosted: 24 Jul 2017, 07:19 
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I took all of the data points that were closest to 170 IAS and averaged the data...Average IAS: 171, Average NM/Gal: 8.5....I see low 8's to high 7's for nm/gal going 310+ ktas
We don't know how they collected their data points so comparing them to your own, with differences in engine and possibly other things, may be apples to oranges. To get at the efficiency of the airframe, as Austin was saying, at higher airspeeds it's better to hold constant as many variables as possible by using their data. From eyeballing the chart, they show 210 KIAS as giving about 6 NM/Gal vs. the 8.5 NM/Gal at 170 KIAS, or 40% more fuel per mile. While a different engine will move that curve up or down its shape is a function of the airframe and shouldn't change so the proportional cost of going from 270 to 330 KTAS at FL 280 should be the same for you, about 40% greater fuel burn per mile.

Of course, turbine operating cost tends to be dominated not by fuel but by the hourly engine reserve for HSI and overhaul, and going 330 vs. 270 true will put almost 20% fewer hours on the engine, which offsets the extra fuel burn some. Will that be enough to pay for the extra fuel expense? Beats me, I haven't run the numbers. Apparently Austin didn't think so.

Well again, my point was to show that you can still have a fast plane and have similar fuel burn per nm. In Austin's blog he stated that planes were flying 10 nm/gal at 170 indicated with the -135A. This chart from what I can tell does not demonstrate that. I'd be very curious as to where he received that information.

The only plane I see in the chart showing near 210 KIAS is at FL200 so I would think that would explain the low NM/Gal.

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 Post subject: Re: You say you want an Evolution ...
PostPosted: 24 Jul 2017, 09:40 
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Beats me, I haven't run the numbers. Apparently Austin didn't think so.


You doubt the grandmaster of simulations? :D

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 Post subject: Re: You say you want an Evolution ...
PostPosted: 19 Sep 2017, 22:32 
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It's been a while since I posted anything and shop time hasn't been very photogenic (carbon layups all look pretty much the same) so, New topic: Help me with the paint scheme. This is our leading contender. Colors are silver-gray (although it looks white here), charcoal-gray and blue. Want to keep the top cowl over the engine all silver so the stainless cowl fasteners don't leap out at you, dark leading edges to see ice and charcoal at the wing root to hide the wing/body join. It's OK as far as it goes but we want to jazz it up some.

Comments welcome!


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 Post subject: Re: You say you want an Evolution ...
PostPosted: 20 Sep 2017, 00:04 
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It's been a while since I posted anything and shop time hasn't been very photogenic (carbon layups all look pretty much the same) so, New topic: Help me with the paint scheme. This is our leading contender. Colors are silver-gray (although it looks white here), charcoal-gray and blue. Want to keep the top cowl over the engine all silver so the stainless cowl fasteners don't leap out at you, dark leading edges to see ice and charcoal at the wing root to hide the wing/body join. It's OK as far as it goes but we want to jazz it up some.

Comments welcome!

Very nice! I like it.


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 Post subject: Re: You say you want an Evolution ...
PostPosted: 20 Sep 2017, 00:16 
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Needs Color....

You asked for opinions...


Red thin strip, following the blue, instead of the black line... But i think it needs color. Blue and white are pretty, but you may get tired of how plain it looks.


BTW, Great project. Congrats.

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