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What cruise settings do you use most often?

B

BigglesRV7A

Well Known Member
Fellow Pilots,
I am interested in what other pilots are using for their cruise settings and associated performance with their selected setting.
I have an RV-7A with a FADEC controlled IOF-360 and where possible I elect to use the following settings::)

RPM-2350
MAP-21.5"
TAS-160kts
FF-29.5L/hr
DA-8500
Indicated HP - 65%

I can fully open the throttle and or increase RPM to fly into the mid 175KTAS though fuel burn correspondingly increases as well as noise levels hence I elect to cruise comfortably at the above settings.

Interested in your experiences.

Cheers, Greg
 
Settings

I generally run 23 squared till I'm above whatever altitude the manifold starts to drop, then it's full throttle, 2300rpm, LOP burning about 6.5 gph with about 165kts TAS. If I want to burn more gas, I push the fuel flow up to just short of 10gph and true out 173kts. IO-360 angle valve RV-8 with Robert Paisley's EFII dual electronic ignition.

That ignition system sure helps get the LOP fuel flow down. Saving 3gph by slowing down 10-12 kts is sure worth it!

No this is not a paid advertisement!:D
 
OPTIMUM


Wide Open Throttle ALL the time except when in the yellow arc on descent or on downwind and landing. This is the maximum efficiency for the engine.

anywhere around 2400-2500 wherever it is smoothest. (2000-2100 on descent)

Ranging from 60-80dF LOP at high powers (approx 80%) down to 10-20dF LOP at higher levels below 65%. If in the flight levels and I want more power I will run 75+dF ROP, but that is not efficient.

Greg, check your PM's, I see you are down in Sale, Victoria. ;)
 
cruising up high
brianphonesep12094.jpg


race prep....this was 13gph 2600rpm. sorry the pic is chopped off. It's tough to take a no-glare pic while running flat out looking for birds.
aviation2012012.jpg


A lot of my flying is between 8500-12500. I flight plan for 175kts 9gph and always do better than that.

b
 
High and fast.

In my -10...23", 2375, 15.5 GPH, ROP and 175 Knots at 7,500'.

Yeah, it's a high fuel burn but the airplane was bought with the intention of running in the 200 MPH range OFTEN:)

Best,
 
old school 6A, mags o-360 FP sensi 85", 150KTS, 8 gal/hr ROP car gas/100ll mix. :)
 
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Most 4 bangers run best (smoothest) around 2400 RPM (+/- 50).

Normally for cruise if I'm trying to get somewhere I run:
2400 RPM
22"
10-20 deg. LOP which yields around 7.5 GPH @ 165K Avg.

Just puttin around town I will run the same RPM at 19-20" with lower fuel flows (6.5 GPH). Lower power settings = greater TBO :D
 
Higher is better, especially with the F1 EVO wing. My power settings at cruise are in the 55 to 65% range. I run at best power, 50 ROP. LOP works, I burn less fuel per hour, but I also lose about 10 knots.
On a three hour flight like this, LOP would have saved me 1.4 gallons and added about 10 minutes to the flight. That 10 minutes does not sound like much but it comes right off my TBO. I know that experimental do not have a regular TBO but they DO eventually wear out and extra engine hours ARE extra engine hours. This expense needs to be considered when calculating the true savings while running LOP. Besides, if I wanted to go slow I would have a different airplane!

Typically at 5000' I file 200 knots, 12 gallons
at 10,000' I file 210 knots 11.5 gallons
at 13,000' see below! 218 knots TAS, 10.6 gallons per hour.

At lower altitudes I will run a higher MP then RPM, say 23" and 2200 rpm, up high I do not have that choice and 2300 seems like a nice smooth number.

2qso1s7.jpg
 
mannanj said:
...I generally run 23 squared till I'm above whatever altitude the manifold starts to drop, then it's full throttle, 2300rpm, LOP burning about 6.5 gph with about 165kts TAS...
Click to expand...

What altitude do you fly where you can still pull 165 knots on 6.5GPH? I run WOT from takeoff until I "intercept" 23 inches on the way down at my destination, then I maintain that MP until in the pattern. Typically I'm at ~8000 feet and the best MP I see is 21 inches, with 2350RPM, 50LOP and 8.2GPH at 165+TAS.

165 @ 6.5 is impressive for an -8!
 
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RV10inOz said:
OPTIMUM


Wide Open Throttle ALL the time except when in the yellow arc on descent or on downwind and landing. This is the maximum efficiency for the engine.

anywhere around 2400-2500 wherever it is smoothest. (2000-2100 on descent)

Ranging from 60-80dF LOP at high powers (approx 80%) down to 10-20dF LOP at higher levels below 65%. If in the flight levels and I want more power I will run 75+dF ROP, but that is not efficient.

Greg, check your PM's, I see you are down in Sale, Victoria. ;)
Click to expand...

+1. Pretty much this for me. WFO throttle at all times and RPM to set power level desired. I like 2400 or less but will run 2500 if I am in a hurry. Most of the time Peak or LOP. The only time the throttle comes back is if I am relatively low altitude and I don't want to run so darn far oversquare (lyc power charts allow about +4 inches but the OWT still gives me the willies). My CHTs have had good balance since the beginning but I continued tweaking and on a recent flight the total span was 5 F across all four. Made me smile.
 
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Lots of answers

Some good feedback from regular travellers. As always it is a trade off between speed and fuel usage. 160KTAS at 29.5l/hr or 172kTAS at 38L/hr.

22% extra fuel usage for 7% extra speed. Still the application gives us a choice.

Please send in your settings and performance so that we can get a good cross section of what everyone uses on those longer trips.:)

Cheers, Greg
 
I too am running Superior IO360 and Catto 3 blade.
Cruise at 165 kts at 2450rpm, 8.7gph LOP.
Seems to be my sweet spot.
 
O-360-A1A with Hartzell CS (non blended airfoil). Cruise at a typical 6500-9500ft is usually 23 squared (or WOT and what I can get for MP at altitude). 170kts +/- TAS @ ~8gph or 165kts +/- at ~7.5gph, but I don't have my fuel flow dialed in quite yet. Maybe a tenth or two gph higher than that. I'm carb'd so can't get to the -70 LOP that you injected guys seem to be able to without it getting rough, but the red knob can still make a difference in fuel and cruise speed.

Of note, if I lean aggressively (just under the point of it getting rough... around 30 LOP or so) it will seem to cruise along just fine, but every now and then feel like it misses on a cylinder. Disconcerting over the Rockies out here. I twist the red knob a bit and it likes it more, for a bit more gas.
 
LettersFromFlyoverCountry said:
would like to see some more responses from FP guys (the po' folk).
Click to expand...

As mentioned above... "full rental power", e.g. wide open and mixture peaked for highest rpm. With my original Aymar Demuth wood prop, at 8000' that would give me a bit over 2600 rpm and 195 mph TAS with full tanks and burning 8.9 GPH. Once the tanks ran down past 1/2 full and the CG would begin to shift aft, the TAS would creep up towards almost 200 mph. That prop seemed to be pitched a tad tall, but was a great flatlands cruising prop... not so good for climb while heavy or flying in the mountains though.

It's going to be curious to see what the new Sensenich ground adjustable prop will be capable of. It's supposed to arrive via UPS today :D
 
Neal@F14 said:
As mentioned above... "full rental power", e.g. wide open and mixture peaked for highest rpm. With my original Aymar Demuth wood prop, at 8000' that would give me a bit over 2600 rpm and 195 mph TAS with full tanks and burning 8.9 GPH. Once the tanks ran down past 1/2 full and the CG would begin to shift aft, the TAS would creep up towards almost 200 mph. That prop seemed to be pitched a tad tall, but was a great flatlands cruising prop... not so good for climb while heavy or flying in the mountains though.

It's going to be curious to see what the new Sensenich ground adjustable prop will be capable of. It's supposed to arrive via UPS today :D
Click to expand...

I knew it was a matter of time before someone used MPH, lets stick to knots TAS
 
It depends ...

How much gas costs. In Texas I ran WOT more often than not, or between 2400 & 2500 rpm at low level.

In the land of expensive gas - around $12/gallon - (eastern side of the pond) I run between 6 & 7 gallons/hour. That's around 2150 to 2300rpm with my fixed pitch prop, and I get between 130 and 145kt. I'm normally at low level (2000' and below) as flights are usually short - 30 to 40 minutes - and the airspace often won't allow much higher.

Pete
 
I fly my IO-320 catto 2 blade 68x76 RV-3 at 9-10,000 feet, 2500 rpm, 6.1gpm, 151KTAS. The prop is too underpitched for lower altitude cross country flights. It trues out at 184KTAS @ 1000 feet, 2950 rpm.
 
Not everyone is saying which engine, which type of propeller and which model RV. It would be nice to plot the results, but a little more information would make the analyses more interesting.
 
Like many, when I want to get there in a hurry (or have a huge headwind) at 8,000+ I run 2650rpm, 9.7 gph and that gives me 175kts TAS.

USUALLY, I'm not in such a hurry and I run 2500rpm, 8.5 gph and 160kts TAS.

Like others have said, Higher is better, most of the time.
 
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