Long Cross Country puts Corvair to the Test

Flew nearly 1000 miles from Delaware to North and South Carolina and back last week in my 3000cc Corvair powered 601XL and came away with a renewed confidence and appreciation for the combo.  

The trip to visit family and attend a conference originated at Eagle Crest Airpark (DE25) in Delaware and included stops in Farmville, VA (KFVX), Morganton, NC (KMRN), Greenville, SC (KGMU), and Spartanburg, SC (KSPA) before heading home.  

The 3 liter Corvair engine burned an average of 6gph cruising at 115-120mph TAS. That means that with two 12 gallon wing tanks (22gal useable), N601DR can easily fly two hour legs with more than an hour reserve fuel still available.  This enabled the 460 mile trip from DE to upstate SC to be made with just one stop.  

Total flight time was a hair under 9 hours.  For comparison purposes, Google maps says that driving this would cover 1,250 miles, taking just over 20 hours.  Flying commercially would require a 2.5 hour drive each way to and from BWI, 3 hours flight time, and at least an hour of sitting at the airport before each flight, so maybe 10 hours total?  

The nitty-gritty...

The trip down on Tuesday morning was calm and beautiful with a slight headwind giving a consistent 107mph groundspeed.  The first hour of Saturday's return trip was just the opposite with a nice 125mph groundspeed at 5,500msl.  Unfortunately, the entire central and northeast region was blanketed by a 3,500' ceiling trapping humid, turbulent air underneath. I dropped below the ceiling, reduced my airspeed to VA (around 100mph), and lost the benefit of the nice tailwind.  I still made the trip in 4 hours, but could have shaved almost an hour off if it weren't for the weather.   

Though this experience I learned a lot about flying, planning, and weather.  I transitioned both class B and C airspace, benefited from flight following, landed at both controlled and uncontrolled fields, navigated both visually and by gps, and proved to myself that I am truly a pilot.  

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Comment by Bob Hartunian on March 9, 2016 at 10:09pm

I had a 912 with high comp pistons that probably made ~90 hp and could accept a wooden GSC 2-blade gnd adj prop. But when I changed to a 912S, the old prop could not absorb the higher power, so I installed a 3-blade, 62" Warp Drive and it does take all the power engine can make. One good thing about a wood prop is that it does run smooth by absorbing engine pulses and in case of a prop strike, it destructs and keeps energy from damaging engine.

If you have demonstrated stalls with loaded plane with Corvair engine and no adverse reactions, I'd call that successful.

Up here in mtns, you set prop for climb initially to clear ridges at 8500' and then experiment by adding pitch to make higher cruise speed and try for the best compromise of both. The Warp Drive with tapered tips does good job of climb and cruise.

Comment by Jon Reddick on March 8, 2016 at 3:26pm

Bob,   The Corvair is definitely heavier than the 912.  From what I recall, it is in the 200-220lb range once installed with all it's accessories.  My experience has been that flying with a passenger actually puts the CG right in the sweet spot so that very little trim is needed. I don't really notice any difference in the way it recovers from a stall whether I'm by myself or with a passenger.  It's virtually impossible to load this thing with an aft CG, for which I'm thankful.  The flip side is that another engine manufacturer (so take it with a grain of salt) warned me that it would be way too nose-heavy with one passenger, no baggage and full fuel and would be dangerous in an off-airport landing situation.   Having practiced my fair share of simulated engine out landing's solo, I can assure anyone looking at the corvair that it isn't dangerously nose-heavy.   I will admit that with the gear facing the "normal" way, it is difficult to hold the nose off very long upon landing.  Several folks have experimented with reversing the direction the main gear faces and report a real improvement in that regard.  

As far as the prop, I'm using a ground adjustable warp-drive as specified by William Wynn.  I fly at sea level and rarely cruise long distances, so the prop is currently set to favor takeoff/climb performance.  I did some climb testing up to about 8,500' this past January and still had a healthy 300-500 fpm of climb left at that altitude.

Comment by Bob Hartunian on March 8, 2016 at 2:43pm

Jon;

Thanks for clarification.

I assume the Corvair engine is heavier than 912S but not sure of power it develops. Does increased nose weight effect stall characteristics with 2 aboard? I know it can on Pulsar using the Jab 3300.

Are you running a ground adjustable prop? I fly out of 7K' airport (L35) and having an adjustable prop makes for safer climb margins. Most props are designed for lower altitude flying and can cause issues on climb performance at high density altitude airports. We get 10K' DA at least twice/yr here.

Hope you flight testing goes well.

Bob H

Comment by Earnest Fontenot on March 8, 2016 at 7:30am

Jon, I am building basically the same combination that you have, 650-B w/ 3000 cc Corvair. Thanks for the numbers and inspiration! Last weekend I rented a Cherokee for a XC flight. At WOT it did 105-110 kts IAS burning about 8 - 9 gph. Getting the same speed with less burn is what I;m looking for. Some people want more speed - speed - speed, which is fine but, I want more fly - fly - fly!! Thanks again for the report, it shows that my decision to pick this combo is the right one for me.

Earnie

Comment by Jon Reddick on March 7, 2016 at 9:37pm

Bob, the plane will do 130 flat out.  I've got 1k rpm climb so there is the possibility of giving up some of that for more cruise, but the vne is 140, so I think the limitation is more the airframe than the engine.  

Joe, farthest trio prior to this one was an hour each way.  

Comment by joseph aloof on March 7, 2016 at 7:33pm

HI  JON,   BEFORE THE  LONG X COUNTRY, WHAT WAS YOUR LONGEST FLIGHT WITH THE 601??   JOE

Comment by Harold Bickford on March 7, 2016 at 6:48pm

Looks like you had a great trip. Much more interesting than flying at 35,000 feet. The accomplishment is yours both in building and flying.

Harold

Comment by Bob Hartunian on March 7, 2016 at 6:18pm

Are the speeds posted, ~115 mph, typical for the 601? I would have expected higher IAS with the bigger engine.

Was the prop adjusted for climb rather than cruise? As a comparison, I fly a Pulsar XP with a 912S and cruise at 140 mph burning 4 1/2 gph with a Warp Drive 3-blade prop. The 701 I'm building now would be a major speed contrast but it's intended for visiting rough landing places in Calif desert and not Xcntry.

Comment by Ron Lendon on March 7, 2016 at 6:03pm
Congratulations Jon, Mr. Pilot. I'm planning a long one too. I'll report at the end.
Comment by Thomas Jackson on March 7, 2016 at 5:55pm

Nothing like a good tail wind in life! Sounds like you had a good flight, but watch for those head winds.

Thanks for the documentary.

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