November 1, 2012
Do You Need Long-Range Fuel Tanks?
The mid-October AOPA Summit presented an opportunity to try some longer cross-country legs in the Carbon Cub. Earlier in September we had received the demo airplane from our California Certified Sales Center, California Cubs. N18ZQ was delivered to the CubCrafters Service Center here in Yakima for a new cowl upgrade. I decided to fly N18ZQ to Palm Springs myself for exhibit at the Summit, and then return it to the folks at California Cubs at San Luis Obispo (SBP). At the same time I swapped for a customer’s Carbon Cub, N383RA, and flew it back to Yakima for its own upgrades.
I departed Yakima in N18ZQ, a black and silver bird with 29” Airstreak Tundra tires. On the way to my overnight at Inyokern, California (IYK) I made fuel stops at Lakeview, Oregon (LKV) and South Lake Tahoe (TVL). Day-2 was easy and short. Having been granted permission from Center to fly through R2515 airspace at Edwards AFB (I could just feel the “Right Stuff” coming from that place!), I made a straight line for Palm Springs and an early landing into the queue for the “Parade of Planes”. I cruised at 7,500 or 9,500 and encountered occasional headwinds from 4-15 mph on my trip south. Ground speed averaged 110 mph (clearly reported on the Garmin GDU375).
A few days later, after the Summit, I made a late-afternoon departure from Palm Springs and flew west through Riverside, Ontario, and Burbank airspace to Santa Paula, then steered northwest past Santa Barbara for an evening landing at San Luis Obispo. Aviating and navigating were smooth and enjoyable with the Executive Glass panel in N18ZQ, don’t let that LA airspace intimidate you! Altitude varied from 2,500 to 4,500 through Riverside, Ontario and Burbank, and then climbed to 7,500-8,500 along the coastal mountains.
At dawn on the last day I traded N18ZQ for N383RA, Bob Anderson’s red and silver beauty. Neither N18ZQ nor N383RA have Long-Range Fuel Tanks. During this trip I had plenty of time to consider who might need larger capacity tanks, and when. I knew that the Carbon Cub can be surprisingly efficient when flown higher and leaned out so I decided to see what sort of range I could safely get on standard tanks.
My return north featured great weather with quartering tail winds of 20-30 mph which afforded an eight mph tailwind component. I thought N383RA, with its 26” Airstreak Tundra tires, may have cruised a bit faster than the 29-inch clad N18ZQ, but that’s just an unscientific observation.
I landed at Auburn, California (AUN) and refueled and confirmed that the fuel computer in Bob’s Dynon FlightDEK-D180 was perfectly calibrated. My original plan had been to stop in Klamath Falls for fuel after Auburn, but given the winds and the accuracy of the fuel computer I decided to try for Bend, Oregon (BDN) for fuel and food, and then my last leg to Yakima before dinnertime.
To take advantage of the winds I cruised at 10,500’ most of the way, was in the air 3.5 hours, and burned 18.5 gallons of fuel. The leg measured 361 statute miles and I ran the CC340 engine fairly lean, giving me 19.51 mpg. My previous personal record was 347 sm. I’m sure most of our customers will experience similar performance depending on weather and their power/mixture settings. Of course one should always be careful with fuel management and allow prudent reserves.
So, which tanks are best for a Carbon Cub? If you frequently fly extended trips into the backcountry where there are no fueling options, or if your cross-country flight plans call for 300 miles or more without fuel stops, and if you can stand to be in the plane for over three hours at a time, then the Long-Range Tanks may be a good option for you. For those of us who fly for fun however, the standard tanks can provide more than reasonable range and keep the plane lighter. Remember… “light is right!”