[brad walton]

I recently flew from Houston, Tx to Royalton, NY (9G5) for my Mother's 91st birthday. I have an RV-8 with a Superior IO-360 and Catto 3 blade. On this trip, I got my best mileage ever at 17,200 (with oxygen). 5.7 gallons per hour at 162 knots TAS over rain showers in Ohio. Averaged about 162 knots TAS at 7.8 GPH in the 6 to 8 k altitude range. Truly amazing machines!

 

[Joe]

Good to know, Brad, and thanks for posting.

Did you lean the engine to lean of peak or did you set the mixture to maximum power in order to attain 162 KTAS at 17.2M? What were you indicating for KIAS, RPM, and manifold pressure? And how did the aircraft "feel" at that altitude and airspeed?

I have to believe you have good heat to fly at that altitude, even in the summer

 

[brad walton]

I did not run lean on peak at 17200, Joe because it seems that lean of peak and best power are very close at that altitude. I have experimented with lean of peak at lower altitudes but did not use it on the trip because I am still not comfortable that my engine injectors are balanced closely eough. So for now, travel is at best power usually 65% or less. With the Catto prop, I cruise at 2450 rpm's regardless of altitude and I dont reach WOT until 12 or 13,000 msl. I dont recall the indicated airspeed. I took a telephone picture, but lost it several days later. Seems like manifold presure was about15 inches and IAS was 125. Idid use a little heat, but not much.

 

[Robert Anglin]

Queston?

What type "O2" set up did you use? Was it one of the Hospital bottles, did you use a mask or cannula, were did you find a place for your bottle, oh and did you see a marked increase in "A.O.A." at that altitude? Thanks
Yours as always R.E.A. III #80888

 

[Buggsy2]

On this trip, I got my best mileage ever at 17,200 (with oxygen). 5.7 gallons per hour at 162 knots TAS over rain showers in Ohio. Averaged about 162 knots TAS at 7.8 GPH in the 6 to 8 k altitude range. Truly amazing machines!

Almost 33 statute mpg at altitude at 186 smph, almost 24 smpg at same speed at the lower altitudes. Equal or better to many cars traveling at 1/3 the speed. Amazing indeed! Glad to hear your Catto prop is doing this

 

[brad walton]

O2

I didnt notice an increase in AOA at altitude although I have heard others talk about it. I used an Aerox system from ACS. I mounted it on the floor of the rear baggage. I should have ordered it with the quarter turn regulator for remote turn off and I had to order their Glowmeter that allows flow control at the flowmeter.Oxymizer cannula to conserve oxygen flow.

 

[Robert Anglin]

Interogitory please

These altitudes from about 12K to 18K have long been of great use and interest to me. In Moony 201's and big Cessna singles for long point to point runs, these altitudes "M.S.L." have worked very well. With respect to our 200hp. RV's and the new rules dealing with "ADS-B" it is reasonable to expect we will be going at or a little above the magic 18K level. I know that Van dose note like the idea of us letting down to fast from these levels as it is easy to get into flutter territory if you don't watch your air speed up there. My Question is at 180hp. I know you may not have run a hard data capture so we don't have a lot of empirrical evidence here, so. I think this will be more circumstantial in this case. I wonder if you could tell if there was more altitude to be reached with out dropping to far off the power curve? Do you think you were in the 60-70% of your H.P. range or below? Also could you tell if your "T.A.S." was starting to decay or did you still have some more to get out of this scenario? You know, your gut impressions. Thanks for the time and post on this. I think this may cost me some pizza and beer down the road, my treat. Yours as always R.E.A. III #80888

 

[Chris Hill]

easy to get into flutter territory if you don't watch your air speed up there
I spend a lot of time at high altitude in my 8 flying lean of peak and have never come close to overspeeding the plane. I use a 3 degree decent angle and just position the throttle to maintain my en route MP as I decend at 175-180 KTAS and about 800-900 fpm VVI.

I wonder if you could tell if there was more altitude to be reached with out dropping to far off the power curve? Do you think you were in the 60-70% of your H.P. range or below?
At 18,000 ft, you've climbed through about 50% of the atmosphere and have lost approximately 50% of your horsepower. I've been up at 17.5 with a heavy RV8, and there was still some climb performance left in it. Nothing to write home about though. The best reason I have for going above 10-12k is to catch better winds or get around build ups.

did you see a marked increase in "A.O.A." at that altitude?
If you are referring to angle of attack, yes, there should be some increase in angle of attack with increasing altitude provided TAS is the same as TAS at sea level. Is it "marked"? I guess it just depends on what you mean by that.

I did not run lean on peak at 17200, Joe because it seems that lean of peak and best power are very close at that altitude.
If temperatures weren't a factor, you would want to run at peak egt at low altitudes for best economy. As you climb higher though, temps fall off, and in the teens, I can run peak without getting over 340 CHT/1300 EGT. I use lean of peak to cool the motor at low altitudes (low being less than 12k). I never start LOP operations unless I start with a power setting below 75%. So far, so good (220 hrs).