RV-9 stall speed - accurate or likely pitot/static error?

RV-9 stall speed - Vso (solo)? + do mine look about right?

Does anyone know what Van's no flaps solo weight stall speed is? On their website, they provide the numbers solo and gross for what I assume are flaps down speeds (Vso), but can't find equivalent numbers for flaps up stall speed (Vs) at solo weight.

Went out and did a full stall series and am interested by the IAS's I was seeing compared to the book IAS speeds Van's provides. I'm curious whether my lower indicated stall speed for Vso is what other RV-9/9A's see and whether that's just indicative IAS inaccuracies at such low speeds, whether it's a function of my relatively low empty weight (1039# me, 1057# Vans), whether I likely have a significant pitot and/or static error, and/or whether I have to be more careful at what altitude I do them. (I did mine at about 5000-5500 ft density altitude. Anyone know at what altitude Van's does theirs?)

If you fly a 9 or 9A do my indicated speeds seem in the ballpark compared to yours when you're at 5000 ft density?:
Vso: Vans = 44mph/38kts (solo weight); My plane = 40mph/35kts (solo weight = 180# + full fuel)
Vs: Vans = (can't find Van's Vs numbers for solo weight); My plane = 50 mph/43kts (solo weight = 180# + full fuel)

FWIW, though my GPS speeds seem to match up pretty well with my indicated and true airspeeds when the wind is factored in during cruise, I haven't had a chance yet to really check my IAS in general using the 3-way or 4-way tests and their associated formulas.

Thanks.

....Mine is 52mph no flaps.

CAFE test results

The CAFE Foundation tested an RV-9A some years ago. CAFE no longer has the results posted on their website, but Ted Chang has a copy on his site: http://3limafoxtrot.com/CertificationDoc/rv-9a Cafe report.pdf .

Their test results follow:
Stall, clean, 1759 lb, Vs1 58.16 smph/50.5 kt
Stall, full flaps, 1758 lb, Vs0 49.08 smph/42.6 kt

Leland

CAFE reports are still on their site

You've just got to dig a little deeper.
http://cafefoundation.org/v2/pdf_cafe_apr/rv-9a.pdf
Go to "research" on the bottom of their main page.
By the way, the numbers on my 9A are within a half knot of their findings-just another reference point.
Terry, CFI
RV9A N323TP

terrykohler said:

By the way, the numbers on my 9A are within a half knot of their findings-just another reference point.
Terry, CFI
RV9A N323TP

Click to expand...

My 9A numbers match yours within half knot Terry

Mine too . . .

Stall, clean, 50 kt
Stall, full flaps, 43 kt

Near gross

When I did my testing 4 years ago:

44 mph with flaps
49 mph no flaps

Greg

My -9A gross wt stall speed is clean is 53 kts and full flaps 47 kts. Dan

Looks to me numbers are all over the place and the most likely cause is pitot geometry. Because of this, IAS is meaningless from plane to plane, and determining an accurate calibration factor at the lower airspeeds is practically "mission impossible".

It is what it is for YOUR plane, what else matters and what's a few mph between friends?????

rv9av8tr said:

Looks to me numbers are all over the place and the most likely cause is pitot geometry. Because of this, IAS is meaningless from plane to plane, and determining an accurate calibration factor at the lower airspeeds is practically "mission impossible".

It is what it is for YOUR plane, what else matters and what's a few mph between friends?????

Click to expand...

+1, The stall speed for your airplane is extremely important for you in your airplane. Your stall speed in your airplane is not that important for me in my airplane. And vice verse.

Exactly my point