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CARST
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Cirrus SF-50 - Engine & engine location

Fri May 19, 2017 10:43 am

Seeing see photo of the SF-50 cockpit in the current A.net top 5 photos, I checked out the aircraft a little bit on Cirrus homepage and Wikipedia.

I find the the decision to only use one engine very odd. And also to place it on top of the cabin, instead of probably behind the cabin, with air intakes on top, below or to the left and right (like on a single engine fighter jet), that's another odd choice.

I know that having less engines is usually more economical, but a aircraft intended for private usage is probably not under the same pressure as a passenger airliner competing with other products. So a 10-15% higher fuel consumption and some more MX costs shouldn't be the problem.

So why that choice? Was there no smaller engine available? Couldn't they have gone with two engines, either underwing, overwing or behind the cabin to both sides?

And for the location of this single engine, why? It seems to my unprofessional eye like a highly inefficient positon and angle...

What are your thoughts on this?
 
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lightsaber
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Re: Cirrus SF-50 - Engine & engine location

Sun May 21, 2017 3:54 pm

The drive to single engine is to cut purchase costs. Turbine engines cost a million dollars or more. As to smaller engines, this is a Williams FJ-33-5A, a tiny engine. I do not know this variant's thrust, but the family has a maximum thrust of 1,900 lb (In development for the competing D-jet) little cost savings buying a smaller engine as the expensive parts are all the same engine to engine.

Once you choose to go to one engine, it must be on the aircraft centerline. To put it low would have added weight (cost) and required much more complex air ducting (cost). It is not a very optimal position, but I cannot figure out anything better that wouldn't have added $100k or more to the aircraft cost. A 2nd engine a million (Cirrus has put in other costs vs. the competitors, hence why there isn't a million difference in price point). The most efficient inlet to a jet engine is a sort round inlet. Due to interactions with the aircraft, the inlet is a bit squashed. But this is far more efficient than two inlets feeding a single engine (look at all the surface area that is drag for the air into the engine and drag outside). It is well done to achieve the price point.

Take a look at photos in flight (from this link). The plane flies a bit 'tail up' which dramatically improves the cruise performance. All the photos I've seen in the database that show the engine are nose up, which makes the engine look... too much of a downward angle. But in cruise, it looks right.
http://jalopnik.com/the-cirrus-vision-s ... 1719194739

SF50 is certified, now to deliver, 2nd link shows 6 already delivered:
http://www.flyingmag.com/cirrus-vision- ... tification
http://www.ainonline.com/aviation-news/ ... production

<i>"The $1.96 million Williams-powered jet will reach buyers at a rate of about one a week. The Duluth, Minnesota, company has about 600 orders for the jet, many of them from pilots moving up from SR-series piston airplanes, production of which has been held to 300 airplanes a year."</i>


Seriously, all your questions come down to cutting costs and packaging the aircraft parachute. Please recall weight had to be kept down to use an aircraft parachute which will lower insurance costs; the whole airframe can be rescued by the main chute. So engine packaging had to be compromised for parachute packaging. There is also quite a bit of compromise to get the extreamly low 62kts landing speed (which cuts insurance costs and allows a novice pilot to fly the SF50 safely after a two week type certification course).

With 600 orders, obviously I'm just not affluent enough to be in the market. ;) With 75% of orders to current cirrus customers, this is actually a really smart business plan. They have affluent customers who like their current piston products but want to upgrade. Cirrus, by going one engine, has achieved a discretionary price point for the current cirrus single engine prop owners to upgrade to. Since the SF50 follows many current Cirrus design philosophies, current owners have a very easy upgrade (as intended). Cirrus apparently knows their current customer wishes and delivered. Please put those sales in perspective, it is more than any one competitor (late edit to clarify): Hondajet, Cessna Mustang, and Embraer Phenom 100.

Really the only downside of a single jet is the requirement to overhaul the engine twice as often. But wait, each overhaul costs the same as a smaller engine on a twin, so the per takeoff maintenance burden is the same with a much lower entry price point.

Here is the neat thing, when they are ready to take on the Hondajet, Embaer Phenom 100, and Cessna M2, they will build a twin jet at the $4.5 million price point a twin competes at. (The Eclipse lacks some features that I consider essential, but by doing so maintains below $3 million). For now, they compete for less than $2 million and have that market to themselves. With so much pressure in the business jet market, how would you have stood out with the added costs of a twin, a minimum of $1 million more? They'll be an established player in jets before they have to take on the established competition; a really wise business move. Also, by the time they have a twin out, they'll be able to persuade some fraction of the current SF50 owners to uphttp://www.barrons.com/articles/the-2 ... 50883grade ensuring sufficient launch orders.

There major competitor, Diamond, had a single engine D-jet in development at the exact same price point. Now that plane has better engine placement. However, something is really wrong in the specifications on Wikipedia. Someone tell me how the D-jet with less MTOW weight, a heavier and thirstier engine, less fuel, only 5% more cruise speed, yet has 20% more range. I'm not getting that math... In particular since twin engine inlets cut engine efficiency more than a single (even if non-optimal) inlet.

Cirrus has done a great job identifying their market niches. Heck, over 5,000 SR22's have been delivered with over a thousand SR20s too.
You should read a bit about the parachute. Now that the training has been improved, the aircraft parachutes have dramatically cut the accident rate for Cirrus products (it did take a decade to refine the SR22 training though). There was an obvious gap in the market for a single engine owner pilot flown jet. Cirrus has delivered.

Lightsaber

2nd late edit:
Wow, I didn't realize this thing would be flying in and out of 2,200ft runways (easy!) That will appeal to many current Cirrus aircraft buyers. I wonder if aspirations to fly the SF50 might help Sirrus prop sales...

<i>"Still, the SF50 promises to be a good short-field performer, taking off in as few as 2,036 feet and landing in 1,721 feet."</i>
http://www.barrons.com/articles/the-2-m ... 1473450883
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lightsaber
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Re: Cirrus SF-50 - Engine & engine location

Sun May 21, 2017 7:17 pm

I was thinking about this thread while hiking (I know...) and I realized there is really a small gap for owner operated business jets below the *faster* and longer ranged turboprops (Cessna Denali, SOCATA TBM 900, and Pilatus PC-12) which will be tough to compete with in the $4Million to $5 million market unless going head to head with the Hondajet, Embraer Phenom 300, or Cessna M2. Every time I thought about the market, there was a huge need to keep costs low (single engine).

Seriously, many of the turboprops will be faster, but it takes quite a bit of money to make an even faster jet. I think Cirrus planned well keeping under $2million and that can only be done single engine.

Lightsaber
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flylku
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Re: Cirrus SF-50 - Engine & engine location

Sun May 21, 2017 8:39 pm

At Oshkosh this year it was really clear that their target market is own/operators of aircraft used for business. You start the the SR-20. Move up to the SR-22T and then finally the Vision Jet. Single engine aircraft with similar systems albeit one graduates to a jet. I actually know a business owner who was in the process of doing this when last I worked with him.
...are we there yet?
 
dw747400
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Re: Cirrus SF-50 - Engine & engine location

Mon May 22, 2017 8:29 pm

I know that having less engines is usually more economical, but a aircraft intended for private usage is probably not under the same pressure as a passenger airliner competing with other products. So a 10-15% higher fuel consumption and some more MX costs shouldn't be the proble


At this level, private aviation is very price sensitive. When you move up to Gulfstreams and private airliners things may change a bit, but a lot of folks in the turboprop and entry level jet space are trying to get the utility of private aviation at a minimum cost. This is why the TBM, the PC-12, and other single engine turboprops are so popular. Also, a large part of the target market already is already operating single engine aircraft, so they are comfortable with them.

Seriously, many of the turboprops will be faster, but it takes quite a bit of money to make an even faster jet. I think Cirrus planned well keeping under $2million and that can only be done single engine.


I agree... for a given mission the jet is going to burn a bit more, be a bit slower, and carry a bit less than the "premium" single engine turboprops, but Cirrus has three major things going for it. First, as you noted, it costs a lot less to purchase. Second, Cirrus is already leader in the owner-flown market, and a lot of SR-owners that have been going to Meridians or older turboprops now have a great new option. Finally, Jet appeal will certainly make a new SF-50 look attractive next to a used TBM that is around the same price, even if the TBM is a bit more "sensible" numbers wise.

Wow, I didn't realize this thing would be flying in and out of 2,200ft runways (easy!)


The single engine will help here as well; no VMC issues to consider, no go/no go decisions. You could get the same numbers safely in a twin, but all your costs would rise accordingly.
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lightsaber
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Re: Cirrus SF-50 - Engine & engine location

Tue May 23, 2017 2:27 am

dw747400 wrote:
I agree... for a given mission the jet is going to burn a bit more, be a bit slower, and carry a bit less than the "premium" single engine turboprops, but Cirrus has three major things going for it. First, as you noted, it costs a lot less to purchase. Second, Cirrus is already leader in the owner-flown market, and a lot of SR-owners that have been going to Meridians or older turboprops now have a great new option. Finally, Jet appeal will certainly make a new SF-50 look attractive next to a used TBM that is around the same price, even if the TBM is a bit more "sensible" numbers wise.

I agree with the three points. They know their owner/operator pilots and are appealing to that target market.

Oh, I'm not naive enough to think they'll get 100%, but I'm floored by the backlog of 600. Certainly doing better than the Eclipse 500/550/"Canada".
To think back in 2008 the Eclipse was over $2 million. It sold well enough, but didn't have a good business case. I think the Cirrus has a far better business case (Profit for the airframer).

And yea, the TBM or other used turboprops will have more 'sensible' numbers. Cest la vie. To paraphrase Star Trek: "I'm an engineer, not a psychologist!"

Honestly, I had stopped following VLJs/single engine jets after watching so many efforts fail or cease production. I'm glad one is moving forward, I really thought there was far more potential in the market.

Lightsaber
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kurtverbose
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Re: Cirrus SF-50 - Engine & engine location

Tue May 23, 2017 10:25 pm

Funny, the Heinkel HE-162 Salamander was designed to be simple and cheap to build too.

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