1
$\begingroup$

enter image description here

I am interested in identifying this prop airfoil due to its uncommon high .92% efficiency (the best metal props are closer to 83-87%). I have done an exhaustive search for it. It is labeled "NACA RML 9 G 06a". I do not know where I originally got this plot and therefore have no way to know what "ref 3" is.

It does not appear to be a airfoil number and a google search doe not return any "NACA RML" however I have a library of about 2000 "NACA RM" which refers to NACA Research Memos; perhaps the additional "L" means "Letter(s)".

I can find NACA reports starting with "RM G-10" but no G-9. I have also searched for derivatives of "06a" in an airfoil number. I would appreciate any assistance in identifying this airfoil.

$\endgroup$
3
$\begingroup$

The label you seek is not an airfoil, it is a research memorandum produced at Langley. (RM Lxxxx) The subject airfoil is NACA 4-(5)(08)-03 and the maximum efficiency from the test as reported in the conclusion was 88% at m0.71, partway down the curve where compressibility effects become adverse. enter image description here enter image description here

$\endgroup$
  • $\begingroup$ Thanks... wonderful! I see now the chart label was wrong and that explains why I could not find it. $\endgroup$ – jwzumwalt Jun 8 '18 at 2:19
  • $\begingroup$ @jwzumwalt What, if anything, did you wind up doing with the airfoil? It has interesting performance. $\endgroup$ – Pilothead Aug 6 '18 at 20:26
  • $\begingroup$ I am installing a VW engine in a home-built aircraft of my own design and was intrigued by the high speed efficiency. A VW engine is rated at 5000rpm but 3800-4000 (other builders typically run them at ~3400rpm) is more realistic and this puts a 55-60" prop near the speed of sound. This airfoil is about 5% better than similar designs at that speed. $\endgroup$ – jwzumwalt Aug 6 '18 at 23:10
  • $\begingroup$ @jwzumwalt How will you get the airfoil coordinates? It is not numbered like any NACA series with which I am familiar. Hope it works out for you. $\endgroup$ – Pilothead Aug 7 '18 at 0:25
  • $\begingroup$ I have pictures of it, and it appears to be similar in design and characteristics to a NACA 10-(5)(08)-03, NACA 4508 or 5508. dtic.mil/dtic/tr/fulltext/u2/a801420.pdf <br> airfoiltools.com/airfoil/… $\endgroup$ – jwzumwalt Aug 7 '18 at 2:18

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.