some 9A performance numbers

[FrankK90989]

A few numbers from my 9A.
0-320 D2J 160 hp.
2580 rpm.21.5" MAP.
I am getting what Van's advertises -and would get better but the Sensenich prop is limited to 2600 rpm, and I need upper leg fairings.
Some things to think about when you order a prop.

 

[cobra]

Frank, what is your propeller spec? FWIW, I believe your numbers are quite typical from other reports Ive seen. Do you believe the prop twist (speed limit) is the problem here (is the engine capable of higher rpm)?

The way I see it, the recommended engine/prop combination should be able to consistently meet cruise speed specs as a minimum target, and possibly be capable of a bit more speed when conditions warrent. Ive had the suspicion for a while that 160hp might be a bit shy of fulfulling the 9's full design aspirations.

Quick Dynon question- is it possible to program the aircraft's actual speed "colors" into the display?

 

[FrankK90989]

Frank, what is your propeller spec? FWIW, I believe your numbers are quite typical from other reports Ive seen. Do you believe the prop twist (speed limit) is the problem here (is the engine capable of higher rpm)?

The way I see it, the recommended engine/prop combination should be able to consistently meet cruise speed specs as a minimum target, and possibly be capable of a bit more speed when conditions warrent. Ive had the suspicion for a while that 160hp might be a bit shy of fulfulling the 9's full design aspirations.

Quick Dynon question- is it possible to program the aircraft's actual speed "colors" into the display?

Prop is 70Cm7S9-0 (79) from Van's , and yes I do have more throtle left but cant go there.
Van's spec for 160 hp is-"75%@8000'= 189MPH".
The Dynon is programable "colors" on the tape readout not the numbers.

 

[IowaRV9Dreamer]

Prop is 70Cm7S9-0 (79) from Van's , and yes I do have more throtle left but cant go there.
Van's spec for 160 hp is-"75%@8000'= 189MPH".
The Dynon is programable "colors" on the tape readout not the numbers.

Hi Frank - I'm years from this point on my 9A but I really appreciate your posting. I had spoken to an engineer at Sensenich regarding this prop for a 160HP O-320 and he told me that I wouldn't be able to overspeed (>2600 rpm) the prop in cruise. I wonder if some additional pitch (like going to 80) would help? He also told me the 2600 rpm restriction wasn't going away, it is based on real / measured vibration data.

Thanks again for posting actual data,

dave

 

[vlittle]

Frank:

Have you calibrated the Airspeed? I found my airspeed to indicated about 4% low, even though I did a manometer calibration on the ground. With everything corrected, I'm right on Van's performance numbers.

I have the same issue with the prop. I need to go to 9500' before WOT. After a lot of computation and flight tests, I determined that the Van's intake system plus my Superior sump system is giving me about a 1" MAP boost over what would be expected. This means that I need to go to 9500' for 75% HP. At 8500' It's about 78% (all altitudes PA, with temperature corrections).

I use the Dynon/AOA pitot.

Vern Little

 

[FrankK90989]

if you are getting 188 mph...van's brochure number for 75% ppower at 8K' is 186 mph. I'd say a prop that allows max rpm up to 8-9K' is perfect. It will turn up enough for a decent takeoff and remain in a perfectly acceptable rpm for normal cruise altitudes while running wide open. Can't do much better than that.

I think you'll find that 160 hp is PLENTY for a clean RV-9/9A. After all the prototype would do over 170 mph on 118 hp. Of course you can force it to slightly higher speeds with more hp, but then the old Vne thing we read in the RVAtor might come into play

Yes I am. I'm certainly not complaining these are happy numbers

 

[PaulR]

Speed Question

I'm not to familier with all the things the Dynon will display. Is the 188 shown to the left of the airspeed tape the True A/S?

 

[db1yg]

Paul,

If the Dynon D100 in the pic works like my D10a (which I am sure it does) the ias is 166 and the tas is188.

Cheers,

db

 

[Kevin Horton]

Have you calibrated the Airspeed? I found my airspeed to indicated about 4% low, even though I did a manometer calibration on the ground. With everything corrected, I'm right on Van's performance numbers.

Vern - If I understand you properly, your ground calibration shows that you don't have an ASI instrument error, so you probably have a static system position error (assuming no leaks, and a conventional pitot tube location). Did you use Van's pop-rivet static ports, or something else?

Where are you measuring the OAT you use to convert from TAS to CAS?

 

[az_gila]

Good mechanical airspeed indicator

Frank,
Very nice correlation between the mechanical airspeed and the Dynon IAS.

Do they use the same static port and pitot?

The mechanical altimeter is off by 10 ft. though.....

gil in Tucson

 

[rvbuilder2002]

I think it is perfect!

With the way I fly cross country I would not change a thing.
If you will rarely fly above 8000 ft then I would add a little pitch. If you will, then it is perfect. By having a little throttle left at 8000 ft you can keep pushing it in as you go higher. As you go higher the air density reduces, drag reduces, so the true airspeed increases since you are able to keep the man pressure constant (sort of) by pushing in the throttle as you continue climbing. I would be willing to bet you can easily get above 190 at 10500 with the setup you have now.

The secondary value of leaving the pitch where it is, is takeoff and climb performance. As we all know, a fixed pitch prop. is a compromise in performance at some point. If you were to add more pitch you will reduce your takeoff and climb performance.

A fixed pitch climb prop. VS fixed pitch cruise prop. on an RV is a misnomer.

A climb (lower pitch) prop is a cruise prop. for high altitude. If you have a pitch that allows 2550 - 2600 at full throttle at 11500 you will be producing somewhere around 65 pwr getting great TAS with a very economical fuel flow if properly leaned out.
I flew my 160 HP RV6A this way for years truing at 190 MPH burning between 7.0 & 7.5 GPH.

 

[petehowell]

More Data

I got 4.5 more hours in one flight today towards my 40. (7.5 more to go) I took some data at 4500 feet. I think I crunched it right.

I also found a nice economy cruise at 17.6/2200 4.5 GPH (20 LOP) and still faster than the 172 I used to fly full out! At 17.6/2200 all the cyl go lean at the same time.

Nice numbers, I think.

ECI O-320 Hartzell CS Prop.

 

[Mel]

Gil, I think if you look at the picture closer, you'll see that the Dynon is set at 30.13 while the mech altimeter is set at 30.16. That'll make the 10' diff.
But I wonder why the yellow arc starts at 160 on the Dynon and 180 on the steam gauge.

 

[FrankK90989]

Gil, I think if you look at the picture closer, you'll see that the Dynon is set at 30.13 while the mech altimeter is set at 30.16. That'll make the 10' diff.
But I wonder why the yellow arc starts at 160 on the Dynon and 180 on the steam gauge.

Its because "someone" never remembers to set it. note to self---set Dynon