More RV-3 performance trivia

How about a bit more RV-3 performance trivia to help pass those long winter evenings?
Last time I posted an EFIS screen that documented the cruise efficiency of the RV-3 with MPG as the metric, and you may remember that at altitude I can always get in the low 30s. Today we had a break in the local weather so I went out and flew two configurations that show two other corners of the RV-3 performance envelope... let's take a look.

Flat out top speed
Flying with the throttle and prop all the way forward and the mixture set about 75? ROP for best power it'll do 222 mph TAS, which matches my previous testing exactly. I suppose 13.3 gph isn't too bad for this speed but note that this computes to only 16.7 mpg, not very efficient. Nice to know how fast you can go though.



Lowest possible fuel consumption
Here's the "low & slow" configuration, note the RPM, MAP, and fuel flow. This computes to 39.1 mpg (statute). Who needs a Cub when you can fly and RV-3 along at 137 mph burning less fuel!!



Yea, I know, I'm biased, I think RV-3s are just the coolest little planes around. Just can't contain myself sometimes.

RV-3

I've said it b-4 and I'' say it again... I want one
Dan B
Mesa, AZ

Efficency numbers are almost the same as mine. I came up with 135mph for my RV3 carburator/fixed pitch 10 years ago using not as precise instrumentation. BTW a good "rule of thumb" for this calcualtion is 1.3 X best LOD.
tm

No fare.

In both photos it looks like you are not flying level or does your EFIS just need an attitude adjustment?

(I guess the VSI is showing zero though isn't it)

The VS...

....shows a slight climb in slow flight....

It has been said many times in the past that there are very few airplanes, like RV's, that can do 100 MPH burning under 3 GPH. Randy proves this...thanks,

more numbers

No photos, but here are the numbers for my 160hp, Catto fixed-pitch RV-3B at 8k da.

rpm ff tas % power
2300 5.2 164 45
2500 6.0 177 55
2700 7.2 196 67
2750 7.7 202 72

Low altitude slow/fast flight, yank and bank always averages 6gph. I'll run some numbers at lower rpm's one of these days.

Tony

rvbuilder2002 said:

In both photos it looks like you are not flying level or does your EFIS just need an attitude adjustment?
(I guess the VSI is showing zero though isn't it)

Click to expand...

Yep, my AHRS needs to be adjusted, simple to do. You can see the VSI numbers are zero in both screens so I'm not climbing or descending, and I didn't even notice it so obviously I'm not flying IFR.

Three B or not 3B...

Randy/Tony,

Given all of the above numbers, a CAFE comparison might show your RV3B to be as efficient as anything so far, be it Lancair, John Harmon's Rocket or Dave Ander's Fastback RV4.
Back in the day Mr A. Mooney strove to design an airplane capable of one knot per HP cruise. My 65HP Tcraft would do 85 knots at 4.5 gph. My RV4 would True at 160 Knots at 8.5 gph, the exact same fuel burn over a given distance as the Tcraft at almost TWICE the speed. My HR2 matches my -4's fuel burn over the distance, 30 knots faster. That said your 3B should be even better...

Thanks for sharing...

Smokey
HR2

Hey Tony, any pictures of your new 3B to share?

smokyray said:

Hey Tony, any pictures of your new 3B to share?

Click to expand...

Well, maybe a couple:

http://picasaweb.google.com/tonyboytoo

Tony

Slicker N Snot on a doorknob...

Tony,
Very nice, unique color.... I especially like your placard under the Dynon! I'll try to find the picture of my squadron buddy Vandal's -3 I flew back in the early 90's. It was built in 83' and had 3 class C1A world records painted on the side. One was for absolute altitude at 20+thousand ft! The others were it's time to get there...

The best part about the -3 was the same as the F16...no witnesses!

Smokey
HR2

PS:BTW Randy, it was 82 here today...C'mon down!

Tony Spicer said:

No photos, but here are the numbers for my 160hp, Catto fixed-pitch RV-3B at 8k da.

rpm ff tas % power
2300 5.2 164 45
2500 6.0 177 55
2700 7.2 196 67
2750 7.7 202 72

Low altitude slow/fast flight, yank and bank always averages 6gph. I'll run some numbers at lower rpm's one of these days.

Tony

Click to expand...

Catto quoted me an increase of about 7 mph for each 100 rpm increase which is consistant with your first 3 examples
In the last example you are showing a 6mph increase for a 50 rpm increase. Not realisic.
Sorry
tm

TM, ????

tin man said:

Catto quoted me an increase of about 7 mph for each 100 rpm increase which is consistant with your first 3 examples
In the last example you are showing a 6mph increase for a 50 rpm increase. Not realisic.
Sorry
tm

Click to expand...

rpm ff tas % power
2300 5.2 164 45
+ 13
2500 6.0 177 55
+ 19
2700 7.2 196 67
+ 5
2750 7.7 202 72

I don't see the 7 mph pattern.

Kent

kentb said:

rpm ff tas % power
2300 5.2 164 45
+ 13
2500 6.0 177 55
+ 19
2700 7.2 196 67
+ 5
2750 7.7 202 72

I don't see the 7 mph pattern.

Kent

Click to expand...

Kent
You're right. I got fixated on the first delta @ 13. Catto says that each
100 rpm should net about + 7mph. I think his record keeping is innaccurate, hence the +19 delta in the second example and the +5 delta in the third.
tm

Here is some data from my prop testing. All numbers are at full throttle. Race Prop (Catto 68x82), Cruise Prop (Performance Props 67x79). More proof that different prop makers measure pitch differently. RPM/IAS/TAS

Race
3000 2940/226/236
8000 2850/202/228
12000 2820/184/218

Cruise
12000 2670/183/218

Interesting is that both props provided the same speed @ 12000 with a difference of 150 rpm. My airplane has a lot of aero and cooling mods and was in full race trim when tested.
Tin Man
RV3 978TM
0320/ carb / fixed pitch / EI / Vetterman exhaust