Just what it needs, a way to run out of fuel faster.

How is it that an SF-50 needs 1900 lbs thrust to fly like a dog at low altitudes and an Eclipse goes way faster, way higher, on 1800 lbs thrust?

Answer: inefficiencies caused by being a single engine jet. That decision ripples through the entire design killing performance.

Mike C.

Why is it that the TBM with one engine is faster and more efficient than any other twin turboprop on the market with less total HP and it does not apply to this se jet?






Just what it needs, a way to run out of fuel faster.

How is it that an SF-50 needs 1900 lbs thrust to fly like a dog at low altitudes and an Eclipse goes way faster, way higher, on 1800 lbs thrust?

Answer: inefficiencies caused by being a single engine jet. That decision ripples through the entire design killing performance.

Mike C.

[quote="Marc Bourdon"]Why is it that the TBM with one engine is faster and more efficient than any other twin turboprop on the market with less total HP and it does not apply to this se jet?



Maybe because it is an S ducted jet flying at turboprop altitudes, it's literally a fish out of water. The bummer is that it seems to be as noisy as a turboprop too. Fixing the noise and getting it up high might help a lot. It's very cool that we have a company at least in the game!

The fuselage is a ton smaller?

Chip-

Just what it needs, a way to run out of fuel faster.

How is it that an SF-50 needs 1900 lbs thrust to fly like a dog at low altitudes and an Eclipse goes way faster, way higher, on 1800 lbs thrust?

Answer: inefficiencies caused by being a single engine jet. That decision ripples through the entire design killing performance.

Mike C.

Welcome back Mike. I missed you. Hope you are well. BT just isn’t the same without you. Not sure if Cirrus will eclipse the 100 units delivered by year end 2018 but it will be close.

Peace,
Don

Sam - if these were passive, their contribution to performance would be negligible as has been discussed before. If fear of introducing points of failure is what guides innovation, there would be little progress made in aviation. Active load alleviation is not new and has decades of proven service by airplane makers such as Boeing and Airbus. Here is one such example - https://www.flightglobal.com/news/artic ... er-319049/.

Regarding the failure modes, they were thoroughly tested throughout even the most extreme cases - if you just realized they were active, I would suggest you also dig deeper and research how they were tested and certified - and what happens when and if they fail. Lots of speculation going around the CJ2 accident with nothing definitive pointing one way or another. Let's wait and see.

Sam - if these were passive, their contribution to performance would be negligible as has been discussed before. If fear of introducing points of failure is what guides innovation, there would be little progress made in aviation. Active load alleviation is not new and has decades of proven service by airplane makers such as Boeing and Airbus. Here is one such example - https://www.flightglobal.com/news/artic ... er-319049/.

Regarding the failure modes, they were thoroughly tested throughout even the most extreme cases - if you just realized they were active, I would suggest you also dig deeper and research how they were tested and certified - and what happens when and if they fail. Lots of speculation going around the CJ2 accident with nothing definitive pointing one way or another. Let's wait and see.

Just what it needs, a way to run out of fuel faster.

How is it that an SF-50 needs 1900 lbs thrust to fly like a dog at low altitudes and an Eclipse goes way faster, way higher, on 1800 lbs thrust?

Answer: inefficiencies caused by being a single engine jet. That decision ripples through the entire design killing performance.

Mike C.

They should have removed the cabin and put the single engine in the middle of the fuselage, right where it belongs.

Because props and jets are different.

A jet needs to fly high to be efficient, in the 40s. A TBM can't even get there.

To get a jet up there, though, you need redundancy in the pressurization. A single engine could be designed to do that, but it's complicated. By far the easiest way is to have a second engine.

And then there's the problem of where to put that one jet engine. In the SF50 case, it results in so many aerodynamic compromises. Canted, so needs deflector plate. Inlet in low pressure area over fuselage. V tails to avoid fin in jet blast. V tails require large wetted area. Stability augmentation system requires more control surfaces, so it ends up being an X tail. Being limited to low altitude, burns lots of fuel, so heavy fuel loads. Mounted high, so lots of trim change with power. Lots of trim drag. And so on.

All the other SEJs have similar jet engine location problems. Djet use efficiency robbing S inlets for a buried install, also caused icing problems. PiperJet put the engine in the fin a la DC-10. Complex structure, lots of drag. Eclipse 400 was a Vtail, so has SF50 problems. There just isn't a good planform for an SEJ used to haul around people.

The most efficient place for a jet engine is on a pylon like normal business jets. Also isolates much of the noise, which is a serious problem in the SF50. A jet where passengers have to wear headsets? Yuck. Pylons are also the safest place for a jet engine. Really bad things can happen and the plane still lands.

Mike C.

_________________
Email mikec (at) ciholas.com

Mike,

Why does a PiperJet style engine/tail add lots of drag? I get the structural issues, but of the single engine configuration choices it seems like not such a bad option. (Well it is ugly...)

Conceptually it seems like the drag for a vertical stabilizer mounted engine could be made quite similar to the drag of a rear fuse pylon mounted engine. You have the same number of intersections in both cases and the fuselage/nacelle geometry/interaction could also be made pretty similar.

David

I have a new tenant coming to our hangar. 2019 February delivery of a cirrus jet and he told me the story of how he came to choose cirrus jet. He flew tbm, m600, even looked at Pilatus.... interesting details.
- he’s a highly qualifiable buyer. You can google his name to qualify him. He couldn’t even get a test flight in a cirrus.... he tried... there are guys standing in line for a test flight and new planes.
- he finally finagled a test flight.... after the other TP options... His wife said... this is the plane. No comparison. He said the same thing. It’s the fit/finish ergonomics of the aircraft. It’s the UI. Scrunching hunched over yoga move to get in the other planes with small windows..... It probably seems normal to us because we’ve always sweated in 172’s, hot started turbo pistons, and yoga’d to the front of a meridian....

But this is new UI. New experience. It’s never been available at this price point and size of aircraft. It’s the size of a baron in my hangar.

Then he went about trying to buy one. he wanted new and had to buy a position which wasn’t easy....waiting at the end of the line was not remotely an option. It’s a long line. He also explained how cirrus protects the position holders.... they are fair to them and customer oriented.

He’s moving up from a 206 and it’s a perefect step up aircraft. He had the 206 for 5 years so it’s not like his ticket is still wet. No doubt, he fits cirrus potential customer profile perfectly. Btw, he liked the M600 and asked piper ‘if I order one, when can I get it.’ Next month, they said. Cirrus has clearly tapped a market.

Can’t wait for it to arrive in the hangar and see it.

Classic. What’s a joke to me might not be a joke to someone else. It’s a personal thing, Flight.