tuna hp
9th Jul 2012, 19:06
We know very little about Dassault's Falcon SMS project other than that it is going to use SNECMA Silvercrest engines which are designed to produce from 9,000 to 12,000 lbs of thrust. We know that Dassault had originally selected 10,000 lb Rolls Royce RB282 engines, but later reneged on that decision, remarking that they 'wanted more power'.
At the beginning the "Falcon SMS" project seemed to aim to create a spiritual successor to the super midsize, midrange Falcon 50 (hence the name). As we've learned more about the engine selection process, the prospect of this plane having something like a 900 ft^3 cabin and 3500nm of range is seeming less and less likely.
First there was the selection of those 10,000 lb RR engines: the Falcon 2000LX, which Dassault has historically marketed as a "heavy" aircraft as opposed to super midsize, has only a pair of 7,000 lb engines. Then Dassault apparently ditches those RR engines to select a pair of higher power Silvercrests...
This mystery plane had me puzzled so I started to do some rudimentary calculations about what kind of plane Dassault could actually build assuming they were to use the most powerful available Silvercrest engines. For my group of comparison planes, I chose a large selection of the most sophisticated planes of the last couple decades:
-Falcon 7X
-Falcon 900LX
-Falcon 2000LX
-G650
-G550
-Challenger 605
-Global 6000
-Global 8000
I then recorded the MTOW and max thrust for each plane. I found that the the planes had thrust-to-MTOW ratios between .27 and .36 lbs-thrust/lb-MTOW, with an average of .32 lbs-thrust/lb-MTOW.
Based on that number, I can calculate that a new plane using a pair of 12,000 lb thrust Silvercrests should be able to have an MTOW of around 75,000-76,000 lbs.
The Falcon 7X only has an MTOW of 70,000 lbs. That means that according to my rudimentary and possibly severely flawed estimates, if Dassault does choose to use Silvercrests with the maximum available power, they should be able to build a plane that is slightly larger and longer range than the Falcon 7X.
But why would Dassault do this and possibly cannibalize sales from their 7X program which would be nearly the same size airplane?
One reason is that the market for ultra-long range business jets has proven to be by far the most lucrative and stable over the past couple decades. Customers literally cannot get enough of planes like the G650 where delivery slots are supposedly booked out 10 years into the future! The only players in this market are Gulfstream, Bombardier, and Dassault, so the competition so far has been limited.
In comparison, nearly every airframer has released or will be releasing a new super midsize in the near future. Depending on how you define super midsize, these planes could all be considered entrants:
-Citation X / Ten
-Challenger 300
-Hawker 4000
-Gulfstream G280
-Legacy 500
-Falcon 2000S
The super midsize market is overcrowded with options and there isn't enough demand. To release a low-cost-to-market variant like the Falcon 2000S into this fray is one thing, to invest many hundreds of millions on a clean sheet design to compete here would be suicidal.
Another facet could be that Dassault figures that twinjets and trijets are really very different airplane choices, even for about the same size plane, and therefore do not worry about cannibalizing sales. All else equal, a trijet plane is going to be more expensive to buy, more expensive to maintain, and more expensive to fuel than a twinjet, so they really are for people who feel more comfortable flying on 3 engines or who have to follow regulations that advantage 3 engine planes. Yes I know obvioulsy Dassault Falcon's have been significantly more fuel efficient than the similarly ranged Gulfstreams that they have been set up against, but the reality is this is mostly due to the Falcons being being much smaller and lighter planes. Dassault could feel that that there are still enough customers out there who will demand 3 engines to ensure the viability of of their 7X program years into the future, even if they release a newer plane that is slightly larger and longer range.
But then if Dassault was trying to compete more in the large cabin ultra-long range market why wouldn't they just use variants of airliner engines like Gulfstream and Bombardier do and build something comparable with 90,000+ lbs MTOW? Dassault has a history of making lighter planes than their competitors, and of building their airplanes around the best available engines. The SNECMA Silvercrest is a slightly "disruptive" engine in that it is the most powerful engine ever developed that has a centrifugal compressor. Centrifugal compressors are more efficient than axial compressors and as far as I know are a feature on every single smaller turbofan engine such as those fitted to light and midsize business jets. However, as turbofans get bigger it becomes harder and eventually impossible to use a centrifugal compressor. So while new airliner derived turbofans like the GE engines that are going to be used on the Global 7000/8000 might be more efficient per lb of thrust produced than Silvercrests, the Silvercrests should be substantially more efficient than any 12,000 lb thrust engines produced before them, and a smaller/lighter plane built on the Silvercrests should still use much less fuel per mile than heavier planes like the G550/650 and Global 6/7/8000.
Does anyone have any insights into where my reasoning may have gone wrong? Any insight into where Dassault is going with their SMS project?
TL;DR: Dassault's currently in-development plane has been continuously referred to "super midsize" but we have have confirmed reports of engine choices that indicate way more thrust than Dassault would need to power such a plane. What the hell is going on?
At the beginning the "Falcon SMS" project seemed to aim to create a spiritual successor to the super midsize, midrange Falcon 50 (hence the name). As we've learned more about the engine selection process, the prospect of this plane having something like a 900 ft^3 cabin and 3500nm of range is seeming less and less likely.
First there was the selection of those 10,000 lb RR engines: the Falcon 2000LX, which Dassault has historically marketed as a "heavy" aircraft as opposed to super midsize, has only a pair of 7,000 lb engines. Then Dassault apparently ditches those RR engines to select a pair of higher power Silvercrests...
This mystery plane had me puzzled so I started to do some rudimentary calculations about what kind of plane Dassault could actually build assuming they were to use the most powerful available Silvercrest engines. For my group of comparison planes, I chose a large selection of the most sophisticated planes of the last couple decades:
-Falcon 7X
-Falcon 900LX
-Falcon 2000LX
-G650
-G550
-Challenger 605
-Global 6000
-Global 8000
I then recorded the MTOW and max thrust for each plane. I found that the the planes had thrust-to-MTOW ratios between .27 and .36 lbs-thrust/lb-MTOW, with an average of .32 lbs-thrust/lb-MTOW.
Based on that number, I can calculate that a new plane using a pair of 12,000 lb thrust Silvercrests should be able to have an MTOW of around 75,000-76,000 lbs.
The Falcon 7X only has an MTOW of 70,000 lbs. That means that according to my rudimentary and possibly severely flawed estimates, if Dassault does choose to use Silvercrests with the maximum available power, they should be able to build a plane that is slightly larger and longer range than the Falcon 7X.
But why would Dassault do this and possibly cannibalize sales from their 7X program which would be nearly the same size airplane?
One reason is that the market for ultra-long range business jets has proven to be by far the most lucrative and stable over the past couple decades. Customers literally cannot get enough of planes like the G650 where delivery slots are supposedly booked out 10 years into the future! The only players in this market are Gulfstream, Bombardier, and Dassault, so the competition so far has been limited.
In comparison, nearly every airframer has released or will be releasing a new super midsize in the near future. Depending on how you define super midsize, these planes could all be considered entrants:
-Citation X / Ten
-Challenger 300
-Hawker 4000
-Gulfstream G280
-Legacy 500
-Falcon 2000S
The super midsize market is overcrowded with options and there isn't enough demand. To release a low-cost-to-market variant like the Falcon 2000S into this fray is one thing, to invest many hundreds of millions on a clean sheet design to compete here would be suicidal.
Another facet could be that Dassault figures that twinjets and trijets are really very different airplane choices, even for about the same size plane, and therefore do not worry about cannibalizing sales. All else equal, a trijet plane is going to be more expensive to buy, more expensive to maintain, and more expensive to fuel than a twinjet, so they really are for people who feel more comfortable flying on 3 engines or who have to follow regulations that advantage 3 engine planes. Yes I know obvioulsy Dassault Falcon's have been significantly more fuel efficient than the similarly ranged Gulfstreams that they have been set up against, but the reality is this is mostly due to the Falcons being being much smaller and lighter planes. Dassault could feel that that there are still enough customers out there who will demand 3 engines to ensure the viability of of their 7X program years into the future, even if they release a newer plane that is slightly larger and longer range.
But then if Dassault was trying to compete more in the large cabin ultra-long range market why wouldn't they just use variants of airliner engines like Gulfstream and Bombardier do and build something comparable with 90,000+ lbs MTOW? Dassault has a history of making lighter planes than their competitors, and of building their airplanes around the best available engines. The SNECMA Silvercrest is a slightly "disruptive" engine in that it is the most powerful engine ever developed that has a centrifugal compressor. Centrifugal compressors are more efficient than axial compressors and as far as I know are a feature on every single smaller turbofan engine such as those fitted to light and midsize business jets. However, as turbofans get bigger it becomes harder and eventually impossible to use a centrifugal compressor. So while new airliner derived turbofans like the GE engines that are going to be used on the Global 7000/8000 might be more efficient per lb of thrust produced than Silvercrests, the Silvercrests should be substantially more efficient than any 12,000 lb thrust engines produced before them, and a smaller/lighter plane built on the Silvercrests should still use much less fuel per mile than heavier planes like the G550/650 and Global 6/7/8000.
Does anyone have any insights into where my reasoning may have gone wrong? Any insight into where Dassault is going with their SMS project?
TL;DR: Dassault's currently in-development plane has been continuously referred to "super midsize" but we have have confirmed reports of engine choices that indicate way more thrust than Dassault would need to power such a plane. What the hell is going on?