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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 20 May 2021, 13:49 
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Username Protected wrote:
The website specs today differ from what Mike listed at page 1. Weight increased, etc.

Item - Cirrus - Flaris - Diff w/ early by Mike
Engine - exactly - the - same
Empty lbs - 3550 - 1984 - +441
Gross lbs - 6000 - 4078 - +778
Cruise knots - 311 - 415 - +35
Wingspan - 38'7" - 28'6"

So, basically what they're claiming here is aerodynamics so clean that their stubby wing provides an acceptable landing and climbing performance, while obviously beneficial for cruise speed.

But the airplane sure has grown, while keeping the same engine.

Still, to have an empty weight that is 56% of the Cirrus's while using the same engine is pretty stunning, and the conclusion is either that they are amazing engineers, or they left out something important.

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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 21 May 2021, 01:22 
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Username Protected wrote:
Still, to have an empty weight that is 56% of the Cirrus's while using the same engine is pretty stunning, and the conclusion is either that they are amazing engineers, or they left out something important.

It could be both.

The Flaris design is actually pretty good conceptually. I'm concerned they have a weight problem from forgetting about all the stuff you need (like deice, for example). But the basic plan form is one of the better ones for an SEJ. The engine is protected from FOD and ice being behind the fuselage. It is on a pylon which enhances safety and quiet. The thrust vector is aligned in the direction your are going unlike the Cirrus SF-50. The engine lacks long intake ducts which rob power and require deice like the DiamondJet. The engine isn't part of a complex draggy fin structure like PiperJet.

They still have the issue of being a single in the upper flight levels, so until that problem is either solved or regulations change, that will always be crippling to SEJ performance.

Mike C.

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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 21 May 2021, 03:29 
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Username Protected wrote:
Still, to have an empty weight that is 56% of the Cirrus's while using the same engine is pretty stunning, and the conclusion is either that they are amazing engineers, or they left out something important.

It could be both.

The Flaris design is actually pretty good conceptually. I'm concerned they have a weight problem from forgetting about all the stuff you need (like deice, for example). But the basic plan form is one of the better ones for an SEJ. The engine is protected from FOD and ice being behind the fuselage. It is on a pylon which enhances safety and quiet. The thrust vector is aligned in the direction your are going unlike the Cirrus SF-50. The engine lacks long intake ducts which rob power and require deice like the DiamondJet. The engine isn't part of a complex draggy fin structure like PiperJet.

They still have the issue of being a single in the upper flight levels, so until that problem is either solved or regulations change, that will always be crippling to SEJ performance.

Mike C.

Good points. They may also have skimped on sound proofing. That can add quite a bit of weight. Not that the Cirrus is super quiet from what I understand.
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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 21 May 2021, 05:34 
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Username Protected wrote:
The engine is protected from FOD and ice being behind the fuselage. It is on a pylon which enhances safety and quiet. The thrust vector is aligned in the direction your are going unlike the Cirrus SF-50.


But the engine position likely causes a downward pitching moment when thrust is increased. Not a good from a safety perspective. From what I recall, Diamond embedding the engine was to avoid this issue. Cirrus likely ran into similar issues.

On the net, but never seen a reference to an AC or reg that I recall, this downward moment on increasing thrust is a deal breaker for the FAA. No idea if this is true or not.

Tim


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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 21 May 2021, 08:34 
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Username Protected wrote:
The engine is protected from FOD and ice being behind the fuselage. It is on a pylon which enhances safety and quiet. The thrust vector is aligned in the direction your are going unlike the Cirrus SF-50.


But the engine position likely causes a downward pitching moment when thrust is increased. Not a good from a safety perspective. From what I recall, Diamond embedding the engine was to avoid this issue. Cirrus likely ran into similar issues.

On the net, but never seen a reference to an AC or reg that I recall, this downward moment on increasing thrust is a deal breaker for the FAA. No idea if this is true or not.

Tim

The engine on the Cirrus should cause a lot more downward pitching moment with increased power than the engine on the Flaris, yet the Cirrus was certified by the FAA. I would be more concerned about a sudden pitch-up from reduction in power.

The Flaris engine still looks like it could suck in a bird pretty easily. I wonder if they could add a bird deflector and/or splitter. Hopefully the windshield would deflect a bird up and over the engine intake. Not sure if that's worked out in real life for the Cirrus, however. CitationMax mentioned in one of his videos that a bird would go right into the Cirrus intake:

https://youtu.be/6hdRVgEg7y0&t=15m5s
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Last edited on 21 May 2021, 09:23, edited 1 time in total.

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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 21 May 2021, 08:56 
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Username Protected wrote:
But the engine position likely causes a downward pitching moment when thrust is increased. Not a good from a safety perspective.

This is like just about every jet out there. The engine thrust line is higher than the drag line, so they pitch down on power application. This is true of any Citation, for example.

But this is actually good because increased speed causes a pitch up naturally from increased lift, so it can be in balance.

The Flaris has the thrust line fairly low, so this effect will be minimal. Not nearly as big an issue as say the PiperJet would be from the high fin location, or the SF50 from the canted engine alignment.

Mike C.

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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 21 May 2021, 14:12 
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Username Protected wrote:
Cirrus likely ran into similar issues.

Cirrus engineers addressed that by adding a little Coanda lip to the exhaust, which directs the thrust somewhat up.


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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 22 May 2021, 23:38 
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Username Protected wrote:
The website specs today differ from what Mike listed at page 1. Weight increased, etc.

Item - Cirrus - Flaris - Diff w/ early by Mike
Engine - exactly - the - same
Empty lbs - 3550 - 1984 - +441
Gross lbs - 6000 - 4078 - +778
Cruise knots - 311 - 415 - +35
Wingspan - 38'7" - 28'6"

So, basically what they're claiming here is aerodynamics so clean that their stubby wing provides an acceptable landing and climbing performance, while obviously beneficial for cruise speed.

But the airplane sure has grown, while keeping the same engine.

Still, to have an empty weight that is 56% of the Cirrus's while using the same engine is pretty stunning, and the conclusion is either that they are amazing engineers, or they left out something important.


My money is on the "journalist" confusing pounds and kilos...

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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 23 May 2021, 01:11 
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Username Protected wrote:
Still, to have an empty weight that is 56% of the Cirrus's while using the same engine is pretty stunning, and the conclusion is either that they are amazing engineers, or they left out something important.


My money is on the "journalist" confusing pounds and kilos...

That's what I thought, too, but it's right on their website: 900kg. https://flaris.pl/aircraft/

Maybe that's sans wings?
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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 23 May 2021, 07:06 
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Aircraft: Bonanza A35 1949
Williams patented a fixed exhaust shape that, at highest thrust, diverted slightly upward. The marketing name was NeXt, and it was part of the PiperJet proposal. From Wikipedia :

"The Altaire would have been powered by the Williams International FJ44-3AP. This model of engine employs a "passive vectored thrust" design that helps compensate for nose-down pitch of the aircraft when power is increased as a result of mounting the engine relatively high up in the tail."


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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 24 May 2021, 06:48 
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Just cottoned on to this thread. Watching Mike Patey and his "Scrappy" build, a clean sheet design out of carbon fiber and milled aluminum could be made both strong and incredibly light.

Modern interior fabrics and materials are quite light vs. just a decade ago (as I am discovering with my own lightweighting project on my 182). Avionics are lighter than before, and almost certainly landing gear will be titanium.

Cabin is smaller in cross section and seating capacity than Cirrus if I am looking correctly.

Adding back de-ice, AC, weather radar (if necessary....not sure that it is anymore) will fatten up the empty weight.

Whether or not there is a market for an owner-flown VLJ that is smaller than a Cirrus remains to be seen. By the time this comes to market it will be competing with proven alternatives (eg. Diamond's twin engine diesels, any of the other turbine singles and of course legacy used twin turbines and twin pistons).

Brian


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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 24 May 2021, 07:32 
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Username Protected wrote:
Just cottoned on to this thread. Watching Mike Patey and his "Scrappy" build, a clean sheet design out of carbon fiber and milled aluminum could be made both strong and incredibly light.

Modern interior fabrics and materials are quite light vs. just a decade ago (as I am discovering with my own lightweighting project on my 182). Avionics are lighter than before, and almost certainly landing gear will be titanium.

Cabin is smaller in cross section and seating capacity than Cirrus if I am looking correctly.

Adding back de-ice, AC, weather radar (if necessary....not sure that it is anymore) will fatten up the empty weight.

Whether or not there is a market for an owner-flown VLJ that is smaller than a Cirrus remains to be seen. By the time this comes to market it will be competing with proven alternatives (eg. Diamond's twin engine diesels, any of the other turbine singles and of course legacy used twin turbines and twin pistons).

Brian

I think there could be a niche market for people looking specifically for the "jet experience". These are people who might buy an L-39 but could be persuaded to go for a more sporty version of the Cirrus SF50 because it's much, much more useful than an L-39 but still fun to fly.

And if you look at the Flaris control layout, you have your right hand on a stick and your left hand on the power, just like a fighter. Coincidence? Maybe not.

The Flaris has almost twice the power to (empty) weight ratio of the L-39. The only thing Flaris needs to do now is make it fully aerobatic and they're in it to win it...

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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 24 May 2021, 10:31 
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Username Protected wrote:
My money is on the "journalist" confusing pounds and kilos...

There were no journalists involved. I went to the websites of the respective companies and copied their claimed numbers -- it's not even Wikipedia. I am quite impressed by +2 on this too. I realize that we're a point where it's socially acceptable to say that journalists will get the bullet first, but come on. Not all ills of this world are the fault of journalists; sometimes aviation startups post wildly optimistic claims.


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 Post subject: Re: Flaris: Polish VLJ
PostPosted: 24 May 2021, 10:49 
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Username Protected wrote:
My money is on the "journalist" confusing pounds and kilos...

There were no journalists involved. I went to the websites of the respective companies and copied their claimed numbers -- it's not even Wikipedia. I am quite impressed by +2 on this too. I realize that we're a point where it's socially acceptable to say that journalists will get the bullet first, but come on. Not all ills of this world are the fault of journalists; sometimes aviation startups post wildly optimistic claims.


Oh how we've gone blind and deaf in the end of days...

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