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RV-10 airfoil data

digidocs

digidocs

Well Known Member
Here is a set of reverse engineered airfoil co-ordinates for the RV-10. They are a bit rough because of the low image resolution, but probably could be massaged into something a bit smoother.

10-foil.png


These were derived this picture of the airfoil on Van's site:

10_airfoil_flap.gif


It would be fun to get some more accurate coordinates for computer performance models, etc.
If I sent you a giant piece of graph paper, would anyone be willing to trace their wing section and send it back?

-David Carr
 
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I believe it's an NACA 23013.5.... used by all Vans Aircraft designs with the exception of the RV-9.

You can play with it in XFOIL for free. You don't have to find the coordinates as XFOIL can plot NACA series airfoils for you.
 
David,

I think that the RV-10 uses a custom airfoil, perhaps from the same family as the -9.

Here are my reverse engineered -10 co-ordinates (pink) overlaid on a NACA23015 airfoil (blue).
NACAvsRV10.png


The two shapes look different enough that I think they are from different families.

I've had several volunteers for the great tracing experiment, and I'm working on a 5x2' sheet of graph paper now!

-DC
 
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Funny

Weird. I always thought it was a 23012.

If it's something else, it would be fascinating to learn the thought process behind why it was changed, and how a different choice was decided upon.

M
 
RV-10 airfoil selection from the man himself: (http://www.vansaircraft.com/public/rv-10int1.htm)

For the RV-10 airfoil we have struck a compromise between the thickness needed for spar strength and a reasonable drag coefficient. The dust settled at 16% thick. With a custom-designed airfoil section, we hope to achieve a somewhat wider range of laminar flow than with the NACA 230 airfoils we have been using. We hope this will keep the drag down even with the thicker section. We know that the lift of a 16% thick airfoil is less than that of a thinner section.

Through the use of carefully designed flaps, we should be able to neutralize this loss, too. As of now, the design calls for a flap span of 51% of the total span, after fuselage width, aileron and tip spans are subtracted. So, since the benefit of the flap affects only half of the wing, we still lose a little, overall, because of the thicker wing.
 
It looks to me like they are still the same family, but it's common for designers to do a little "tweaking". From your plot, it looks like the RV-10 airfoil has a sharper LE radius and the location of maximum thickness is further aft. These changes are often noted by adding a hyphen and two digits to the airfoil name. The first digit indicates a change in the LE radius and the second indicates the location of maximum thickness in % chord. For example: NACA 23016-34 has a sharper LE radius (6 is original radius) and maximum thickness at 40% chord.

It would certainly be interesting to plug both versions into XFOIL and compare CL/CD plots.
 
The RV-10 airfoil is not from the 23000 family. I'll send a link to this thread to the guy who did design the airfoil, and we'll see if he 'fesses up. Or not.

Thanks, Bob K.
 
I talked to the guy who designed the RV-10 airfoil, and he doesn't want to step into the hail storm, positive or negative, that would ensue if his identity were widely known.

However, he has authorized me to say that he is a long-time acquaintance of Van, originally from the soaring community, and is a 30-year practicing aeronautical engineer. The airfoil was a custom, from-scratch design to meet Van's very specific design goals and requirements. It was designed using a program similar to XFOIL, combined with design judgment accumulated over the years.

The characterization of the design goals described in the link to Van's website is accurate, with the addition that there were also constraints on section pitching moment and manufacturability.

Thanks, Bob K.
 
Paper on its way

The mother of all graph paper is born:

graph2.jpg


Its about 60x24". I think that the -10 chord is about 57", so hopefully it will fit.

Here's a close up (the big squares are 1x1"):

graph1.jpg


The package is winging its way towards TN courtesy of the USPS, so hopefully we'll have airfoil data soon!

-DC
 
digidocs said:
The mother of all graph paper is born:...
Click to expand...

That is probably the best solution for reverse-engineering an airfoil where you have access to the unadulterated profile at a root or tip.

For other cases, for instance where the root is buried in a side-of-body fillet or where the tip prevents access to the actual section, you can also use the triple-trace method I describe in Steal This Airfoil.

Thanks, Bob K.
 
New foil data

Thanks to the efforts of a few gracious individuals, I have new and improved airfoil data!

RV-10 airfoil coordinates

Here is a preliminary cruise performance comparison against a NACA23014 (RV3-8)...
Conditions:
2700lbs / 8000 ft /200 mph
Cl .22 / Re 6.9e6

RV10-.22.png


23014-.22.png


Couple of interesting things to note:
The RV10 airfoil is 16% thick compared to the NACA foil at 14%, yet still shows a better cruise L/D.
Also note the much flatter pressure distribution on the -10 foil.

IMHO, it looks like Van's picked a winner with this one.

-David Carr
 
What effect would a faired slot for the flaps have on L/D at slow speeds? Will XFoil compute that scenario?
 
What Bill said!!

We're visiting Georgetown, S.C. and yesterday's flight was an hour total, for 178 miles! 7500', 201 TAS, 23", 2350 RPM,


Yep, they're hard to beat,

Best,
 
I think the best part is the low speed handling. It's great to get somewhere quickly but it's even nice to be able to get in/out of just about any airport out there.
 
rocketbob said:
What effect would a faired slot for the flaps have on L/D at slow speeds? Will XFoil compute that scenario?
Click to expand...

Bob,

I'm not sure if this addresses your question or not, but I believe the RV-10 flaps could correctly be called slotted.

As the flap is deployed, it moves aft and down to open a slot between the wing and flap. To the best of my knowledge, the airflow through this slot re-energizes the boundary layer on top of the flap and delays flow separation. This delayed separation increases the maximum obtainable lift coefficient and thus lowers the stall speed.

-DC
 
Learned that back in '67...

digidocs said:
Bob,

. This delayed separation increases the maximum obtainable lift coefficient and thus lowers the stall speed.

-DC
Click to expand...

...about the Cessna 150's slotted Fowler flaps on the first flying lesson's pre-flight:D

Best,
 
digidocs said:
Couple of interesting things to note:
The RV10 airfoil is 16% thick compared to the NACA foil at 14%, yet still shows a better cruise L/D.
Also note the much flatter pressure distribution on the -10 foil.

IMHO, it looks like Van's picked a winner with this one.

-David Carr
Click to expand...

Really interesting analysis, thanks. I've got one question about the effect of wing loading. It appears you've based everything on producing the same coefficient of lift? According to Van's specs the max wing loading of the RV-10 is actually a little higher than that applied to the older airfoil (18.6 vs. 15.5 for the RV-8). Does this mean that in practice you'd have to operate the RV-10 at higher CL (and alpha)?
 
higher CL or higher speed

To Alan's question: yes, the higher wing loading means that if you fly the same speed, you will be at a somewhat higher CL. However, you can just add a bit of speed (aero forces increase in proportion to V^2) to fly at the same CL.

The slotted flap produces a higher maximum CL, so you can get to comparable landing speeds with a higher wing loading.
 
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