Jon (OP), Mark and Mike,
Here's some side-by-side fun (our photos side by side...and maybe a little play on words for bringing my Super Six into the mix with you Rocket Boyz...
Here's the photos (in this case, 3 of a kind at 214 EFIS TAS):
Mark's
Mike's
Mine:
As Mark said, his EVO Wing performs really well at 17.5K, while Mike and I, with our Sport Wings, do better down lower. Mark's photo above is what sent me out to test similar cruise power performance (but at 13.5K in this case), and I was really pleased to get close to his results. The differences in our manifold pressure and fuel flow is very consistent with our difference in altitude. I know my speed would have dropped off up at 17.5K, as I've tested it, and I watched Mark pull away at 15.5K during AVC 2010 (I caught him in the descent tho!
)
An earlier poster suggested use of the NTPS spreadsheet, and I agree. A 4-way test takes out the one-off performances, and ensures all legs are flown consistently (though the application of its standard deviation calculation). Below is a 4-way test I did in September 2013, just before the Reno Air Races.
The result was 224.0 KTAS, and it turned out to be a good run, with a 0.0 StdDev. Those are rare, but anything below 2.0 is considered good, valid data. 224.0 knots is 257.7 mph, and a week later, I qualified at Reno at 254.7, then in 2014 qualified at 257.3. I was happy with that correlation.
And Mike, that is as close as I could find in my data to the conditions you were running in your photo, from what I can tell. You have a fast machine amigo, and should be up at Reno. By the way, what was your RPM and FF in that run (just can't see it).
Another thing I know Dan H and other sharp-eyed readers will see is that I also recorded my EFIS TAS, which averaged 4.2 knots faster than the calculated result. I know that I have Ram Rise and my TAS readout is a tad high at higher speeds (yep, believe it or not, and I've tested for it too, by adjusting IAS from 70 to 170 in level flight, and watching the 5 degree F change in OAT).
So I reckon now, since I live less than 10 miles from Mark, we need to do some more side by side tests, and see what kind of TAS we can get for Jon (and for Mike to chase!
).
Last note, Todd's 276 mph run at Reno in 2019 was 0.9 mph faster than Bill Beaton's 281 mph qual in his Harmon Rocket a couple year's prior, when the course changes were adjusted out. The speeds at Reno are a completely derived speed, based on time over the set course distance. I'm not saying that to take anything away from Todd or Bill, not at all. As was said earlier, you have to be a bit faster than the final speed on some parts of the course (the Valley of Speed), as the pylon elevation for all pylons is not the same. How one flies the course, manages altitude, g and radius of turn is critical. Todd and Bill set the bar, and I think have a legit claim to being the fastest RV and Rocket in the world. From an RV purist perspective, I guess you could say Bill cheated with a supercharged six, with some nitrous, and Todd cheated with a 100 HP shot of nitrous (plus additional fuel). But its racing, and if you aint cheatin'...well, you know...
It also puts a target on their backs...just sayin!
Cheers,
Bob
Checking the pic I uploaded. I swear I have seen 1KTAS faster, but danged if I can find that one. Headed home from Reno this trip...
Well, I just today took a shot at it and was able to match your speed of 214 KTAS, but down low it was more than DOUBLE your fuel flow. It's still a very dirty airplane though - there is quite a bit more speed in it.