Side by Side - RV-4 vs. RV-8

[Ironflight]

We all know that you can draw a line in any direction through a single datapoint, but here is an interesting tidbit from a cross-country formation flight we took today.

I had left the Valkyrie (RV-8) at Big Bear last Monday while I drove to Carson City. Dayton Murdock volunteered to fly me down to pick the airplane up today, so we launched at 0630 in his beautiful red machine - the RV-4. We had a great flight down the Owens Valley and through the restricted airspace of the Antelope Valley (the female controller was wishing everyone a happy Father's Day as she handed them off), then a hearty breakfast at the Barnstorm Cafe. We mounted up for the return trip about 0945 planning a route formation with me in the lead. It was another delightful trip, with bumps starting to build once we got north of Bishop.

Now for the datapoint. We had carefully topped both planes off at Big Bear, and then we filled them up at Carson City at the other end. Dayton was flying loose formation most of the time, tucking in tight on occasion for the fun of it. For the two hour and ten minute flight, the RV-8 took 17.07 Gallons, and the RV-4 16.6. I suspect that I might have been leaned out a little further than he was, and that might have been why they were close - I would have guessed he'd burn a couple of gallons less over that flight with the smaller, lighter airplane. I was also on autopilot almost all the way, and he was hand-flying - another difference.

O-320 with a fixed-pitch Cato on the RV-4, O-360 with a Hartzell BA on the -8.

But the most important thing of all - we had a good time and enjoyed flight and the scenery of the Sierra Nevada! With the cost of everything else in aviation a gallon or tow (plus or minus) is pretty trivial....

Paul

[sailvi767]

Impressive numbers for the 8 with the bigger engine. Wing man do then to burn a bit more fuel with throttle adjustments but interesting numbers. I also would have thought you would have burned at least 2 gallons more.

George

[g zero]

We flew 4 Bilpanes , Ormond Beach Fl to Oshkosh , an Angle Valve 205 Hp , two Parallel Valve 180 Hp and a o320 160 Hp , all fixed pitch and injected ., The average fuel burn for the three big motors was 9.2 gph the o320 was almost 10gph . I guess o320 were a good choice when they were plentiful and cheap , I prefer the option of burning more and going faster . Mine was the 205hp .
Tom

[AX-O]

Paul,
another important fact to note between your airplanes is that you both have Pmags. So the results are not skewed due to different ignitions.

What were you guys showing for rpm and MP?

BTW, it was awesome to unexpectedly see you guys flying over the house.

[n5lp]

Originally Posted by AX-O

Paul,
another important fact to note between your airplanes is that you both have Pmags. So the results are not skewed due to different ignitions...

Last I knew the Val had Slicks. Am I behind the times?


Working on tractor mag in Carlsbad

[Ironflight]

Originally Posted by n5lp

Last I knew the Val had Slicks. Am I behind the times?


Working on tractor mag in Carlsbad

We swapped to Pmags after that incident Larry....

[scrollF4]

Paul,
One other factor. If Dayton flew on your wing, he'll be burning more fuel than normal because of the sort of throttle modulation inherent to the job of maintaining position. The flight lead's fuel burn will be lower since his throttle remains more motionless. I believe if you flew the same flight again, but the RV-4 led, the gap between fuel burns would be wider in the -4's favor.

Wish I was there...it sounded as fun as you described.

[flyinga]

As another point of reference, we had a similar "loose" formation flight for a little over 50 hours over the past two weeks. RV7A (IO360 parallel) and RV8 (IO360 angle valve). Flights were between Texas and Alaska. We flew mostly 8,500-12,500 feet and usually lean-of-peak. Both have one electronic ignition and one mag. At every fuel stop (usually adding 20 or so gallons) the 8 used about one gallon less than the 7A. It was also interesting flying wing LOP and using mixture for power control.