Well, after our expose' last week on the ratio of empty weight to maximum takeoff weight, I am sure to have established my credentials as a half-wit amongst our learned stress engineer friends.
But why leave things only half done? Ignoring the advice of one of my favorite Presidents ("Don't get caught"... -oops, that was Tricky Dicky...but I imagine that's pretty much what they all say),
"Better to remain silent and be thought a fool than to speak out and remove all doubt. "
(Well, I think Abe Lincoln would not be accused of trying to not-get-caught. Although he was accused of just about everything else- politics was probably even uglier then than now, although it seemed some common sense and civility was briefly evident during the 1950's through 1980. Oh well, accidents happen).
Anyway, here we go with a review of business jets (or let's say, business aircraft- as I've included a few turboprops. All twins though, (well, or triples, or quadruples, in a few cases. And, a few Single Engine Jet's...Make that ALL the SEJs :). I deliberately did not include pistons, just to try to try to keep the scope narrowed. I'm sure I also missed a number of great foreign (and probably domestic) aircraft which would well qualify for inclusion- go ahead and mention your favorites, and I'll put them in the tables.
I believe it was Julius who mentioned the Beech Premier as being a notable exception to the laundry list of "failed" composite programs. And inconvenient truth, as it were, to my thesis that composite aircraft (commercial anyway) are:
1) Heavier than their aluminum counterparts
2) Cause cancer and baldness and explode all the time
(Okay, just kidding about that last one:)
My discomfort with a "disruptive" outliar- oops, not talking about former Eclipse stuff- some would insist that the correct terminology in that case would be out-right liar; however in this case: Outlier (interesting read, btw) variance of the Premier program, into the realm of commercially successful composite airplanes, did prompt me to compile a short list of what I had considered "failed" composite airframe programs, versus their nearest successful aluminum competitors. The results were modestly surprising, and challenged a few perceptions I have held about some of these programs. (These are the numbers I found on the web, ymmv, etc.; please post a correction if you see anything too far off, but I believe these numbers use the same methodology, allowing reasonably accurate comparisons).
Adam A-700 versus the Cessna Mustang. I had always thought the Adam looked like a porky little critter, and would surely be a heavy pig compared to the Mustang. But weight ratio wise, no- the Adam was quite respectable (the Mustang isn't too bad either). I suspect the aerodynamics of the A-700 weren't quite as good though. But, the composite Adam failed, the aluminum Mustang succeeded. Not saying it was the airplane's fault- just a data point. This round- Commercial success: Composites 0, Aluminum 1; Technical success: Composites 1, Aluminum 0.
The ,Beech Premier I (a Premier II is in development) versus the CJ2+ was also a bit of a surprise- I figured that since the Premier was successful, it would have a great advantage over the Cessna- but no, the Premier has a "heavier" ratio than the Cessna (which was also a commercial success). This round- Commercial success: Composites 0.5, Aluminum 0.5 (tie); Technical success: Composites 1, Aluminum 0.
The Grob SPn was one of my favorite development programs. Although it was still early in it's development program, with the likelihood of weight gain as certification changes dictated. But it failed commercially. Or rather, the company did. But again, it's a data point. This round- Commercial success: Composites 0, Aluminum 1; Technical success: Composites 1, Aluminum 0.
I think everyone (including me!) wants to root for the Beech Starship. But it was a financial disaster- only 50-ish were built, and all were bought back to be destroyed. (Well, most of them brought back anyway- a few still in circulation: I saw one fly by a few months ago). And it was heavy. This round- Commercial success: Composites 0, Aluminum 1; Technical success: Composites 0, Aluminum 1.
The last comparison is the Hawker Horizon/4000 versus the Bombardier Bd-100/Challenger 300. (The names of both airplanes changed over the past few years, as indicated). These two airplanes are about as close as it gets to direct competitors- they even had their first flights just 3 days apart. The Horizon is another airplane that has been a financial disaster, with a long development program, and low deliveries to date; the aluminum CL-300 has been a great commercial success. But, the Horizon is slightly better weight ratio than the CL-300, so I'll give it the technical nod. This round- Commercial success: Composites 0, Aluminum 1; Technical success: Composites 1, Aluminum 0.
So, "what's the score" for this five-pair comparison?
Commercial success: Composites 0.5, Aluminum 4.5
Technical success: Composites 4, Aluminum 1.
(I biased the technical success in favor of composites- as long as it was not deficient compared to the aluminum competitor).
To me, the surprise was not that the composite airplanes are so well represented in the financial failure category- which is mostly what I have observed. Rather, the surprise was that they indeed really ARE a bit lighter than their aluminum competitors. I guess I had attributed their financial failure to having a poor weight ratio, but it seems that is not the case.
So if the weight ratios are superior, why the financial failures? I would say, one big contributor, is the cost associated with development of a composite airframe. (Of course, it has been a difficult time economically, for all manufacturers, aluminum OR composite- but still, there seems to be some correlation apparent).
Further observations of the commercial ramifications of composite airframe development:
The A380 was 2 years late...
The 787 is over 2 years late...
Grob who was designing the composites for the Lear 85 (as well as their own SPn) went bankrupt.
I'm not saying there is a direct link between commercial fiasco and composites, but it seems the Premier is the only exception to that hypothesis so far. (Yes, there are lots of orders for the 787, so it may eventually break even. And over the course of years, be profitable. But I think it would have been more profitable, more sooner (er, something like that), if it would have been built of aluminum. (And yes, most of these airplanes are largely aluminum. But I still say there is a correlation between using composites and financial success- or lack thereof).
SO- if that was fun, how about comparing ALL the biz jets (and some select turbo props) ??
I strove to use comparable weights (empty without crew). In general, it seems differences in the empty weight:MTOW of 0.02 are where it gets "out of the noise", and 0.05 seemed to be especially relevant.
Another surprise- while the "sturdy" Kingair line dominates the bottom of the empty:mtow ratio table- but it's interesting to note what's at the second-to-last position. (Hint: Hondajet. And rather dramatically so. (We'll be discussing the Hondajet in a future "headline" thread). Almost as surprising, the Bombardier/Canadair Challenger-series came in at the top- in spite of having the appearance of being rather short and, well, dumpy. (Beauty is in the eye of the beholder though- no offense intended. And it has a great weight ratio!)
So, how did "our favorite VLJ" do? The Eclipse EA-500 scored a very respectable 0.597. Given the rumored weight gain, and deviation from the optimal configuration (rumored to be 40% or so)- that competitive number is all the more impressive. (Congratulations to the structural design team!)