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Dominic,
If you are interested in the real speeds of the O-320, I am attaching the CAFE report. If you are interested in more speed stories, continue reading.
In the 2003 Sun 100 I came in second to Bill Harrelson. I took a wrong turn and was off course by 5 miles. I indicated 205 kts @ 2,700 rpm @ full throttle @ 500 ft for the whole course.
In the 2004 Redmond 100 race, I came in first for the 235/320's. I don't remember my true speeds in either of the races but they were the fastest (corrected for distance).
Yesterday, flying from Norfolk, Va to Detroit, Mi about 470 nm, I flew at 154 kts IAS @ 2,350 rpm @ full Throttle @ 8,500 ft @ 7.0 gph. This is a TAS of about 180 kts. The O-320-D1F engine is most efficient (best BSFC) at 2,450 rpm but it feels better to me at 2,350 rpm. I could richen the mixture up to about 8.5 gph (a 20% increase) to get another 5 kts (a 3% increase) in speed. You be the judge or you pays your money, you takes your choice.
180 kts is about as fast as a LNC2(320) cruises without modification.
At 13,000 ft and above, I can't see any speed difference between 2,350 and 2,600 rpm. It must be the prop efficiency. I am flying an Aero composites prop. I fly about 170 kts @ 16,000 ft.
As far as Paul's engine speeds are concerned, Lycoming recommends that an engine be torn down and inspected whenever there has been an overspeed of 10% for more than 10 seconds. On our engines that would be 2,700 x 1.1 = 2,970 rpm. I hit 3,200 or 3,300 rpm with a prop overspeed a couple of years ago but I wouldn't fly that way and still be trying to get somewhere.
Lorn
From: "Dominic V Crain" <domcrain@tpg.com.au>
Date: May 1, 2008 10:26:05 AM GMT-04:00
Subject: TAS
I was wondering – what TAS do any listers get with their aircraft fitted with an O320 at – say 5500 feet - along with power settings (WOT + RAM air), OAT reading.
Just interested.
From: "Paul Lipps" <elippse@sbcglobal.net>
Date: May 1, 2008 1:35:44 PM GMT-04:00
Oscar Grassle's 235/320, with the ELIPPSE two-blade racing prop, would go 242 mph TAS at 1000' dalt at 3200 rpm, 240 mph TAS at 5500' dalt at 3150 rpm, and 233 mph TAS at 10,000' dalt at 3090 rpm; these were predicted and tested values. With his present modified Great American two-blade prop he gets about 219 mph TAS at 8500' dalt at 2660 rpm.
The ELIPPSE two blade prop just designed for a 235/320 is predicted to give 216 mph TAS at 2700 rpm at 14,500' dalt, 224 mph TAS at 8800' dalt at 2760 rpm, and 230 mph TAS at 2300' dalt, 2850 rpm.
--
Lorn H. 'Feathers' Olsen, MAA, ASMEL, ASES, Comm, Inst
DynaComm, Corp., 248-345-0500, mailto:lorn@dynacomm.us
LNC2, FB90/92, O-320-D1F, 1,400 hrs, N31161, Y47, SE Michigan
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