He went faster because.....?
I know Darwin was pretty convinced that his Whirlwind was fast so here is another data point that some other props MAY be faster than the mighty Hartzell:
http://www.attawayair.com/ Pretty impressive speed
He went faster on a cross country race?
Could it be he flew better or the winds where more favorable? (Say another plane w/ the same Hartzell prop flew the same race two years in a row and also gained 11 mph, with the same prop. What does that mean? Too many variables to draw a conclusion. Van says the WW200RV is 2 mph slower than the Hartzell BA. But when you talk 1 or 2 mph you are talking within the margin of error, at least for this data.)
Van's Aircraft found (2,500rpm/8,000ft DA/WOT) the WW200RV (206.9 mph) was a tad faster as the old Hartzell HCC2YK/F7666-4 (205.4 mph), but the WW200RV was 3 mph slower than the new Hartzell BA (72") (208.9 mph). See thumbnail data below.
Prop data is hard to get, record and compare, no doubt. So its ripe for claims. I wish Cafe Foundation ORG would do real flight test on props, fixed and constants speed (but the EAA does not support them any more). Unfortunately some manufactures might not be happy or willing to support it with a donated prop for many reasons, so it would require a lot of volunteers to donate their prop for short term for testing.
Attn: all RV'ers, IF YOU DO PROP/PLANE PERF TEST, Please lets agree on standard condition to test:
-8,000 ft DA (not indicated Alt., fly @ corrected pressure & temp density alt.)
-2,500 RPM (the most common, useful, typical RPM, if other RPM used note)
-WOT (trying for about 75% power, some planes may vary, so note MAP)
-Lean* for best / max power about 130F ROP. 100F-150F range)
Notes: Record TAS by observed IAS, corrected for inst error, temp and pressure. Record GPS runs, preferred method three legs on constant "TRACK". National Test Pilot School, NTPS, has the info and spread sheet to calculate TAS here
LINK. The two-way or box 4-sided-90deg method's with simple averages have more error, especially w/ unfavorable winds. Here's a 3-leg constant heading method but requires 90deg cardinal Hdg's (if you like that better)
LINK. The NTPS method is more general and versatile. For fun do both and the simple 4-leg N, S, E, W average method if you want to burn the fuel. PS LOOK for traffic. Also don't forget to note gross weight, engine or any special info with data, like flt conditions, smooth/turbulent. Part of good flight test is documentation of methodology, what ever or how ever you do it.
(* Caution: Its not recommended to lean above 75% power. Its possible some RV's may be a little over 75% power (2-4%) at 8,000ft DA & 2,500RPM & WOT. With EGT 150F ROP w/ 100LL avgas, you're still safe even if a little over 75% a few points. I'm not cavalier or promoting exceeding limits or Lycs recommendations, but flight test does some times require envelope pushing for knowledge, but do it at your own risk. You have the option to retard the throttle or climb higher to get 75% power at 2500rpm, just note the conditions you recorded the data at. However its better to stay WOT and just record your higher power (RPM/MAP/Temp/DA). Please understand your tach-gauge, airspeed-indicator and even GPS are not 100% accurate. Even if you're perfect, recording bad instruments is like measuring with a microscope and cutting with an Ax. There's always some error, but check & calibrate your instruments. The better the instruments you use, the better the data. That's what I was explaining to Jim, errors are part of flt testing, but it's a matter of knowing where the errors are & mitigating. Doing side by side testing is often a good way to weed out gross error, say indicated airspeed. Two planes flying side-by should indicate the same airspeed, right? Quick and dirty.)
BY USING A STANDARD TEST CONDITIONS WE CAN COMPARE DATA MUCH EAISER
(Kevin Hortons's RV site is fantastic (
LINK) with flight test info and links. With all that info you would think he did flight testing for a living?
)
The WW200RV and BA Hartzell are close, 3 mph, nod going to the BA, which basically makes them top two. The WW 200RV is only $1,500 more than the BA & 17 lbs lighter. The only thing which worries me about smaller sized Prop companies is getting service & parts (worry/concern not fact). WW makes good products and seems to have good customer service. The WW is a very close second choice for me, but overall more than speed, the Hartzell is a better value with better support in my opinion. Also I have a small concern of repair cost and difficulty of repairs on composite props (which is a fact). A small nick/dent on a metal Hartzell may just mean a short file session with the prop still mounted on plane. A composite repair may mean removal, dis-assembly, shipping and higher cost. Small damage easily repaired on a solid metal prop may require replacement with a composite prop. This is not a trivial thing.
(click me & watch me grow)
PS Hartzell where is my free prop? ha-ha