Speeds

Leargo · #1 10-01-2009, 12:30 PM

Anyone know what vso,vx and vy rough idea for Rv-9a is?

Don Jones · #2 10-01-2009, 01:18 PM

....with these from a POH I have.
Vy
Best Rate of Climb
86 mph
Vx
Best Angle of Climb
74 mph
Vs
Stall Speed Clean
54 mph
Vso
Stall Speed Landing Configuration
49 mph

RVnoob · #3 10-01-2009, 01:22 PM

a bit noob OT question here...

seems all the navigations are in kt,
why VAN's spec are in mph?

647jc · #4 10-01-2009, 01:33 PM

A couple comments regarding the RV9 speeds posted. Vfe should be 90 mph for full flap deployment and according to Vans, Va should be 118 mph (not sure if that is solo or gross weight).

Looks like the original post with Vfe and Va has been edited and those values deleted.

Ironflight · #5 10-01-2009, 01:38 PM

Quote:

Originally Posted by RVnoob

a bit noob OT question here...

seems all the navigations are in kt,
why VAN's spec are in mph?

Ahhh...the eternal question!

As a trained Aeronautical Engineer, it was beaten in to me that the REAL aviation world always does things in knots, and my papers would be failed if i used any other units...

As a Commercial and Instrument Pilot, I have been trained to do everything in knots, because that is what the ATC world uses.

In the Flight operations world in which I live, we do everything in knots because that is the engineering standard (see first bullet above...)

Many people like to use mph because the numbers are bigger....

(sells more airplanes because they seem faster - same reason that $9.95 is better than $10 if you're selling somethign...)

RVnoob · #6 10-01-2009, 01:45 PM

Quote:

Originally Posted by Ironflight

...Many people like to use mph because the numbers are bigger....

(sells more airplanes because they seem faster - same reason that $9.95 is better than $10 if you're selling somethign...)

ic... thanks
;-)

terrykohler · #7 10-01-2009, 01:57 PM

If you look on this site for POH's, you'll see a listing for an RV9A. Look carefully at the listed speeds, and then disregard. I think it's an example of using cut and paste from an RV7 rather then generating numbers during flight testing.
That being said, the values I found for my 9A at gross weight were as follows:
Vx = 73 kts
Vy = 84 kts
Vs = 51 kts
Vso = 43 kts

In addition, I used the numbers given by Vans for Va (101 kts) and Vfe (78 kts). Also, you can see test numbers presented by www.cafefoundation.org
which all fall within a knot or two of those above. Their numbers are probably more accurate than mine (better equipment and training), but there is some variation from aircraft to aircraft.
Terry, CFI
RV-9A N323TP

Garage Guy · #8 10-01-2009, 02:18 PM

Quote:

Originally Posted by Ironflight

Many people like to use mph because the numbers are bigger....

I've come to think that was the whole joke behind this thread too: http://www.vansairforce.com/communit...ad.php?t=46423

At 2700 RPM, torque in ft lbs is a bigger number than power in hp. So we like hp but we love torque! If Lycomings turned 5252 rpm, we would like them equally.

Back on topic, when we got our RV-6, the POH and placards on the panel had a mix of knots and mph. I've converted them all to knots now, just to reduce the cognitive load a bit. The steam ASI still has mph on the inner scale, in case I ever need to convert back...

--Paul

RV10Man · #9 10-01-2009, 02:23 PM

I like mph. I can look down at the ground and see the mile section lines. Never been able to locate the knot line.

Marshall Alexander
RV10 N781DM

Flyfalcons · #10 10-01-2009, 02:34 PM

Quote:

Originally Posted by RVnoob

a bit noob OT question here...

seems all the navigations are in kt,
why VAN's spec are in mph?

Wang measuring.