How fast is fast?

flynwest · #1 12-30-2010, 10:17 AM

I have a 8 with the Barrett IO 390 and the 200RV prop. My friends all want to know how fast it is, I always say fast enough. They want to know with all the controls forward how fast? The only time it is full forward is on take off. I usually cruise at 23 square and see 180 knots With all forward it will probably go past vne?

My question to all the hot rod guys is will it be fastest with alll controls forward or should the mixture be 100 ROP and the Prop back some or 2700 RPM's and full rich. And how fast is safe in smooth air. What do you think?

Thanks in advance for the advise. Dan West

pierre smith · #2 12-30-2010, 10:44 AM

...on a 145 mile, 4 leg race course. I had asked Barrett at Sun 'n Fun if I could run the engine WOT for 45 minutes and he said that I could run WOT for the life of the engine and wouldn't hurt it

He then went on to say that there may be a more optimal RPM number for best speed besides 2700, so I experimented on the way over there and found that 2640 increased my speed almost 2 MPH according to the Dynon...just a little more bite in the prop.

FWIW, I went on to set top time of day at 211MPH...exactly what Van says.

Best,

MauiLvrs · #3 12-30-2010, 10:45 AM

Quote:

Originally Posted by flynwest

And how fast is safe in smooth air. What do you think?

That would be the number you get from redline...

Bob Axsom · #4 12-30-2010, 11:07 AM

If you go to www.sportairrace.org and scroll down the page toward the bottom you will find links to every plane in every race for the past four years. If you scan through them you can see all of the speeds for every RV that has raced. The fastest is John Huft he has a modified "360" that he now flys in the RV-Gold class (with the 390s) to give the RV-Blue class (360s) a little relief. Deane Ogden flies a RV-8 with a 390 in the RV-Gold Class. So their numbers may be what you are looking for. How you fly your plane is your responsibility but I doubt these guys are holding anything back. John's top speed was 217.17 kts in the 2008 (tailwind) AirVenture Cup race but his normal top speed is around 201 kts. Deane's speeds are a little slower.

Bob Axsom

DanH · #5 12-30-2010, 02:51 PM

Just flew some ASI calibration runs per the NTPS method. Mine is also an IO-390 powered RV-8, but I'm using a Hartzell BA. "All handles full forward" was 197.8 knots true at 2500 MSL. Nothing was taped, no CG shifting, and I have not yet squeezed down the cooling exit per plan....just a baseline.

There is probably some speed in tweaking mixture and prop, but be cautious. Lycoming has not yet published an IO-390 power chart with a detonation limit line. As I recall, Dick Martin found it the hard way once.

Sig600 · #6 12-30-2010, 04:27 PM

Quote:

Originally Posted by flynwest

I have a 8 with the Barrett IO 390 and the 200RV prop. My friends all want to know how fast it is, I always say fast enough. They want to know with all the controls forward how fast? The only time it is full forward is on take off. I usually cruise at 23 square and see 180 knots With all forward it will probably go past vne?

My question to all the hot rod guys is will it be fastest with alll controls forward or should the mixture be 100 ROP and the Prop back some or 2700 RPM's and full rich. And how fast is safe in smooth air. What do you think?

Thanks in advance for the advise. Dan West

Tell them whatever you want! Do they own airplanes? Add 5 knots to whatever their fastest speed is!

Ron Lee · #7 12-30-2010, 04:31 PM

If they are RV folks go on a breakfast/lunch flight and do a side by side speed run.

flynwest · #8 12-30-2010, 07:53 PM

Thanks for the quick respones. Dan

rvmills · #9 12-30-2010, 11:11 PM

Dan (W),

Good questions, and its good to see Dan (H's) numbers too...I've been wondering, and will continue to watch your experiments with much interest Dan. Hope you'll come out and play in SARL, as you'll be a real competitor in RV Gold (and its fun stuff!).

Dan (H) also gives good advice on the mixture. Since you're in Sacto, you can test down fairly low. As Dan said, don't lean much at full power at low altitude. I've been trying to figure out how much I can lean at sea level races, and have only come back a turn or two, watching the EGT and CHT. I keep them in the mid 1300's and 390's respectively...but don't take that as gospel...in fact I do seek feedback on those numbers, and its variable...mostly good, with the caveat that temps are a bit subjective due to probe placement and differences...usually seen as a relative number. Not sure I have seen any real speed gains from minor leaning, and rich = cooling at high power, so I shoot for that side of things. All FWIW!

Good news is that you probably won't run into Vne issues down low and flying level. Do be careful if you go up high to test...watch the TAS, and be cautions of full power decents....TAS can creep up fast.

Pick a calm day (better for data and Vne comfort level) and run the NTPS GPS test runs, low and level (I just run 4 cardinal headings for ease of flying...its just one method). Run it full BTTW for cooling and see what ya get. Its a fun test hop. Calibrates your ASI and gives you an idea of what you'll run flat out! LAter runs can be experiments with RPM, and it would be interesting to see if lower RPM increases speed...haven't tried that test yet.

And then...c'mon out to Wenatchee and run the Great Northwest Air Race (laid back race) and "calibrate" it some more! We didn't have an RV Gold racer in that race last year!

Lemme know if you want a chase plane on your side of the hill...won't take much arm twisting!!

Cheers,
Bob

Bob Axsom · #10 12-31-2010, 01:20 AM

I extracted the RV-8 speeds from the SARL records and printed them below. The information includes the speed rank, the race, the date, the class, the airplane, the pilot, and the speed in knots respectively. The first number in each row is the rank of the speed relative to all speeds in all SARL races and the last number is the speed in knots.

161 AirVenture Cup 2008 7/28/08 RV Blue RV-8 Huft, John 217.17
207 Rocket 100, 2010 11/20/10 RV Gold RV-8 Huft, John 207.43
213 AirVenture Cup 2007 7/23/07 RV Blue RV-8 Huft, John 204.56
223 AirVenture Cup 2008 7/28/08 RV Blue RV-8 Ross, Jon 202.59
224 AirVenture Cup 2010 7/26/10 RV Gold RV-8 Huft, John 201.97
225 Grace Flight 2009 10/4/09 RV Blue RV-8 Huft, John 201.71
227 Taylor 100 2009 3/16/09 RV Blue RV-8 Huft, John 201.29
228 AirVenture Cup 2008 7/28/08 Sport FX RV-8 Martin, Dick 202.28
230 Pagosa Springs 2010 9/26/10 RV Gold RV-8 Huft, John 200.93
238 Colorado 150, 2008 6/29/08 RV Blue RV-8 Huft, John 199.27
239 Pagosa Springs 100 2009 9/27/09 RV Blue RV-8 Huft, John 199.38
241 Rocket 100, 2010 11/20/10 RV Gold RV-8 Ogden, Deene 198.85
250 Rocket 100 2008 11/23/08 RV Blue RV-8 Huft, John 197.43
252 Rocket 100, 2010 11/20/10 RV Blue RV-8 Rovey, Jason 197.38
254 Texoma 100 4/25/10 RV Gold RV-8 Ogden, Deene 197.15
259 Rocket 100, 2010 11/20/10 RV Gold RV-8 Hajek, Jerry 196.36
263 Rocket 100, 2007 11/18/07 RV Blue RV-8 Huft, John 194.78
265 Sulphur Springs 130 7/18/10 RV Gold RV-8 Ogden, Deene 194.59
268 AirVenture Cup 2007 7/23/07 Sport FX RV-8 Martin, Dick 194.36
270 AirVenture Cup 2008 7/28/08 RV Blue RV-8 Carroll, Alan 193.76
272 Tennessee Valley Air Race 2010 10/30/10 RV Blue RV-8 Rovey, Jason 193.5
275 Texoma 100, 2008 4/20/08 RV Blue RV-8 Christman, Dave 192.88
283 Tennessee Valley Air Race 2010 10/30/10 RV Blue RV-8 Carroll, Alan 192.07
285 AirVenture Cup 2007 7/23/07 RV Blue RV-8 Ross, Jon 192.04
288 AirVenture Cup 2007 7/23/07 RV Blue RV-8 Carroll, Alan 191.77
296 Rocket 100, 2010 11/20/10 RV Blue RV-8 Grover, David 189.26
297 AirVenture Cup 2009 7/27/09 RV Blue RV-8 Huft, John 189.13
300 AirVenture Cup 2010 7/26/10 RV Blue RV-8 Ross, Jon 189.01
301 Taylor 100 2009 3/16/09 RV Blue RV-8 Carroll, Alan 188.96
302 Great Canadian Air Rally 2010 8/22/10 RV Blue RV-8 Carroll, Alan 188.83
303 Taylor 150 4/11/10 RV Gold RV-8 Ogden, Deene 188.69
307 Taylor 100 2009 3/16/09 RV Blue RV-8 Christman, Dave 188.33
310 Sulphur Springs 130 7/18/10 RV Blue RV-8 Rovey, Jason 188.12
311 West Texas 100 6/6/10 RV Gold RV-8 Huft, John 187.99
317 AirVenture Cup 2008 7/28/08 RV Blue RV-8 Schryver, Fred 187.49
323 Pagosa Springs 2010 9/26/10 RV Blue RV-8 Rovey, Jason 186.47
327 Grace Flight 2010 10/2/10 RV Blue RV-8 Carroll, Alan 185.7
329 Texoma 100 4/25/10 FAC1RG RV-8 Slocum, Scott 185.49
331 Grace Flight 2010 10/2/10 RV Blue RV-8 Rovey, Jason 185.32
339 Grace Flight 2010 10/2/10 RV Blue RV-8 Chrisman, Dave 184.94
341 Grace Flight 2010 10/2/10 RV Gold RV-8 Ogden, Deene 184.86
342 AirVenture Cup 2007 7/23/07 RV Blue RV-8 Jordan, Scott 184.85
343 AirVenture Cup 2007 7/23/07 RV Blue RV-8 Schryver, Fred 184.85
363 Pagosa Springs 2010 9/26/10 RV Blue RV-8 Taylor, Craig 183.31
368 AirVenture Cup 2010 7/26/10 RV Blue RV-8 Carroll, Alan 182.98
381 Rocket 100, 2010 11/20/10 ? RV-8 No Name 181.53
384 Colorado 150, 2008 6/29/08 RV Blue RV-8 Carroll, Alan 181.34
391 Texoma 100 2009 5/31/09 RV Blue RV-8 Tuckey, Pat* 180.59
393 AirVenture Cup 2009 7/27/09 Sport FX RV-8 Martin, Dick 180.44
392 AirVenture Cup 2009 7/27/09 RV Blue RV-8 Ross, Jon 180.44
408 West Texas 100 6/6/10 RV Blue RV-8 Rovey, Jason 179.91
413 Pagosa Springs 100 2009 9/27/09 RV Blue RV-8 McCann, Jim 179.42
419 Rocket 100, 2010 11/20/10 RV Red RV-8 Jones, Bryan 179.03
457 Pagosa Springs 2010 9/26/10 RV Blue RV-8 Crosley, Eber 177.21
462 AirVenture Cup 2009 7/27/09 RV Blue RV-8 Carroll, Alan 176.87
469 Top of the Chesapeake 7/11/10 RV Blue RV-8 Robertson, Gordon 176.38
508 Pagosa Springs 2010 9/26/10 RV Blue RV-8 Greenberg, Redge 173.42
516 Texoma 100 4/25/10 RV Blue RV-8 Stanton, Danny 173.1
561 Taylor 100 2007 5/20/07 RV Red RV-8 Jones, Bryan 169.45

Bob Axsom