September 4, 2015
Lancairs and Teslas are two of my favorite things in the world.
But you know the old thing about chocolate and peanut-butter: Combine them and they are even BETTER! (right?)
Sooo…. why not take a sleek little Lancair-ESP AIRFRAME and drop in a bad-ass Tesla P-85 BATTERY AND DRIVE-TRAIN?!?!
The Tesla runs 362 hp… even MORE than the Lancair-ESP is used to… no shortage of POWER!
And you could charge it in your hangar.
Never buy another drop of gas.
And never another fear of being unable to hot-start that engine! And basically no fear of engine failure!
But what would the resulting plane REALLY by like?
And now here is my quick performance summary:
The Lancair ESP is a 4-seat, composite, pressurized, fixed-gear airplane… a really nice model of what a 4-seat airplane should look like.
The fuel-guzzling, difficult-to-start, easy-to-destroy, tempermental engine certainly keeps this airplane from ever being mass-marketable, as does the fact that you can easily get dis-oriented and crash… if you enter a cloud. (What a ridiculous joke! Airplanes can crash if they enter clouds! What a sad indictment of the pathetic state of autopilots and avionics today.)
The absurdly archaic engine and avionics and autopilot, coupled with the difficult-to-use and non-scaleable air traffic control system, make mass acceptance of this airplane impossible, but the airframe, performance, and handling qualities are actually REALLY nice!
The Tesla Model S, I think, represents the state of the art in battery and electric motor technology (Right? Am I right? Does someone else currently do better that I don’t know about?)
Certainly, our family Model-S (ok, my WIFE’S model-S) is the finest machine I have ever owned.
What if we took a Lancair ESP airframe weight, shaped it into a Columbia-400 airframe shape (this is a certified airplane, the certified cousin of the Lancair ESP), and installed a Tesla motor and battery pack?
The Lancair normally carries a 310-to-350 hp Continental IO-550.
The Tesla runs a 362 hp electric motor.
The Lancair normally carries 76 to 105 gallons, weighing 456 to 630 pounds.
The Tesla Model S 85 KW-hour battery pack weighs 1323 pounds.
So if we combined the Tesla drive-train and the Lancair airframe, what weight, power, energy capacity, and performance would result?
The fuselage and engine cooling system could be lower drag due to the tiny engine volume and lower cooling requirements…
So let’s take a look at that potential airplane that could be started on right away:
Lancair ESP empty weight: 1800 lb
Continental IO-550 weight: 450 lb
Lancair ESP Empty weight no engine: 1350 lb
Tesla Model S battery pack (85 kw-hr): 1323 lb
Tesla Model S motor (362 hp, 85% eta): 70 lb
Tesla inverter (for charging): 220 lb
total weight: 2963 lb
What would it fly like?
Well, it would fly quite nicely, and the only sound would be the propeller… no engine noise!
(I am assuming you would distribute the batteries into the nose and wings as needed to maintain the same center of gravity as the stock Lancair).
Now the drawbacks:
The engine: 362 hp output to the prop= 270 kw.
Running at 85% efficiency, the engine will DRAW 317 kw.
An 85 kw-hr battery pack will sustain that engine for 85/317= 0.26 hours of 16 MINUTES.
Hmmm… and Tesla says their big problem with batteries and motors is overheating.
Certainly, when I drive my wife’s Model-S really fast in the South Carolina heat, I come back into the driveway with the cooling fans screaming loudly….
Now what about cruise?
Such a plane can cruise with 100 hp output at 8,000 feet at 130 knots true airspeed.
100 hp output is 74.5 kw at 85% efficiency draws 87 kw from an 85 kw-hr battery pack is of course basically 1 hour of cruise.
So, this plane flies like a nice sporty Lancair (slightly more power and slightly heavier weight than a normal Lancair.. not too bad!), but you can EITHER climb for 15 minutes, OR cruise for an hour, or some combination of the two.
Since I like to always land with exactly one hour of fuel reserve on board, this airplane would be out of my comfort zone the moment it left the ground… hmmm….. and even the THEORETICAL range, with ZERO reserve, is just under 130 nautical miles…
OK let’s try this:
Airplanes have something cars don’t: SURFACE AREA on the wings.
Why not cover them in solar cells to keep us going?
If we cover 90% of the wings and stabilizer with solar cells that run at 35% efficiency,
then we will take in about 900 watts of power on a sunny day… after conversion to the engine or battery, maybe about ONE horsepower.
So, solar cells could add ONE horsepower to a plane like this.
If we cruise at 100 hp, then that means we would need 100 hours of sunlight to buy one hour of cruise.
And we only get sun for maybe 8 hours per day….
OK, electric airplanes may indeed be in our future!
Certainly, they NEED to be to save the environment, and gasoline engines are currently very very finicky in their starting, operation, maintenance, etc… far too finicky and environmentally damaging for them to have wide-spread adoption… but better battery technology is still needed before we have a plane that can actually be USED.