I was looking at dreaming about the top of the line SETPs, namely the Epic and TBM 940.

What got my attention was the cruise speed numbers are within 1%, this despite the fact that the Epic is a 100% clean-sheet composite design with all the aerodynamic advantages that this type of construction has to offer over sheet aluminum construction used on the TBM.

My Lancair Columbia 300 has [had] a very distinct performance advantage over a Mooney Ovation - basically identical climb & cruise performance but with the gear hanging in the breeze, thanks to the extremely efficient aerodynamics that composite construction affords.

So how is it that the Epic can't blow the doors off the TBM despite it's beautiful composite curves and bigger engine ?

The Epic is a heavier plane by about 8% (7400lb vs 8000) plus a bigger cabin and apparently a slower stall speed. Composites cannot make up the delta in weight, bigger cabin and a wing which stalls slower.
To blow the doors off a tbm say for 30 kts more cruise you'd need a huge power increase (approx 30%) based on drag increasing by the cube of speed.

Edward, perhaps you meant to say that drag increases as the square of speed but required power increases as the cube of speed?

The TBM900 got a new cowling based on a CFD redesign and picked up a lot of speed as a result. It blows the doors off of the 700 and 850 models.

Epic doesn't have a big advantage at cruise, but it'll fly at FL340 and get there with a max rate of climb of 4,000fpm. The additional power seems to make more of an impact there but I don't suspect climb rate benefits from composite construction as much as the additional SHP.

Don’t neglect insurability and premium costs

One or two epic hull losses and you could find yourself without an underwriter

Lots of TBMs out there flying

Terry, can the new cowling be retrofitted to the earlier models?

Terry, can the new cowling be retrofitted to the earlier models?

The gas generator is essentially the same between a -67A Epic and -66D TBM, so they’re both making the same power at altitude. ~1825 thermodynamic hp in both, but the epic has access to 1200 vs TBM’s 850 before they’re temp limited

By the time an Epic reaches 18000’, the planes are making the same power.

I think the value proposition for an e1000 over a TBM is being a little cheaper and simpler (no Autothrottle, auto brakes, homesafe), larger inside (although it lacks front baggage compartment), and a little more reach to altitude with a higher ceiling if you’re topping weather. Torque limiter is great for takeoff too.

Some downsides are being the new kid on the block vs an established brand, the windshield limited to 54° C (which is ISA at FL340), and less fuel capacity (268 gal vs 290). The LT had 288 gallons. Not sure why they had to peel back capacity but happened for certification.


Wish the Epic had a 7-8psi cabin, another 1.5 hours of fuel for low pax/long hauls (it has the UL), and a big cabin door to get better access to the baggage area.

No pilot door really necessary since the cabin is easier to get around.

Terry, can the new cowling be retrofitted to the earlier models?

It’d be a hit. Lots of 700/850 owners would bite

There was an article I read a few years ago that talked about the surprisingly small performance penalty of a properly designed wheel pant. Compared to a retract a good fairing on the wheel pant was only about a 5 kt difference for many airframes.

I think metal vs composite isn't necessarily always a win for the composite. You can get some nice lines but they might not in fact be much if any better aerodynamically, and also composites can be heavier than aluminum.

Part of the Columbia's good performance is attributed to the more modern NLF airfoils versus the "vintage" 6-series airfoils found in the Mooney. Composite construction does allow for smoother surface finish without rivets and laps/seams to disturb the flow, so longer runs of laminar flow are achievable, and thus lower drag. When we were laying out the original Columbia (I was on the program in the very beginning) I always thought it was remarkable that we could carry more than a 182 and go as fast or faster than an Ovation, with a wider cabin and more comfort, even leaving the gear out. That was how we were benchmarking it back then. The plane was lofted to allow for a follow-on RG version though! LC-40-FG... Lancair Certified, 40 series, Fixed Gear in case nobody figured out that bit of trivia. A turbo RG would've been a hoot.

It is true that composites can end up being heavier at the end of the day once a design matures enough to be certifiable. Specific strength of a composite material system might look far superior on paper compared to metal, but once real construction details are worked, and other factors are considered, that advantage usually shrinks or disappears. The utility certification of the Columbia drove more weight into the design, unfortunately, but it was thought that might be a marketing advantage at the time when certified composite airplanes were still very new.

I think the Epic is a tremendous plane, but so is the TBM after a few decades of refinement. Much like the Columbia offered similar performance to the Mooney Ovation but with a bigger cabin, I think the Epic can be compared in a similar fashion. I hope Epic succeeds wildly and we get to compared a 2040 model epic to a TBM 1050, or whatever else might evolve in the next 10 years.

Reminds me of how similar the performance is between a 1970 bonanza and a 2020 SR22.

Composites help, but not by a huge amount. Subsonic aerodynamics have been understood for a long time. Carbon fiber is lighter than Aluminum but not by a huge amount because there is more variability in its strength (unless you do very expensive inspections)

Exactly .

Indeed, the Legacy Columbia has significant advantages thanks to the excellent wing design that the composite construction enables.

I find it just a bit surprising the same advantages could not be carried over to the Epic with the same results, hence my OP.