OAT 95F H6 to 8500'

[David-aviator]

Greetings,

The Gary Newsted radiator box plate installation was completed late yesterday and with the temp at 95F this afternoon, I tested it.

For the first time I made it to 8500' without a level off for cooling in these hot conditions. It must be noted, however, while I did not level during climb to augment cooling as in the past, I did manipulate rpm and airspeed to keep coolant temp below 230. Best rpm was 2300 and best airspeed 100-110 KIAS. At least that is what worked today. The EIS 230 coolant temp warning came on a few times as I tried different rpm's and speeds.

These are the numbers recorded. This is with 2 original H4 radiators and a front mounted oil cooler. Also, the right inlet side was closed off forward of the PRSU but not on the left side.

Climbing through 4000' OAT 88F.
Oil Temp = 191 Coolant temp = 227 Gear Box temp = 194

Climbing through 6000' OAT 87F.
Oil Temp = 199 Coolant temp = 228 Gear Box temp = 204

Level at 8500' OAT 76F.
Oil Temp = 202 Coolant temp = 228 Gear Box temp = 214

After 10 minutes at 8500, full throttle 2100 rpm.

Oil Temp = 187 Coolant temp = 217 Gear Box temp = 205

Not too bad for a totally rotten hot humid day in the mid west. There's no doubt these radiators are most adequate for the H4 as many guys have reported. They are OK for the H6 but the new larger units will be better.

One further note. I flew this mission with 87 mogas with 10% ethanol. It tested at 47 kPa's in the hanger at 95F. This fuel had a little 100LL mixed in, but most of it was mogas. Vapor pressure of fuel has no relationship to octane. I had some 93 mogas earlier this year that tested at 34 kPa's.

If you use mogas, it must be vapor tested before each flight.

Dd
RV-7A
N707DD

 

[rvatornate]

David and I are enjoying the same lovely weather by doing the same
things:
Finished up the Newsted radiator box plate around noon. Decided
that flying to Oshkosh without a test flight was probably not the
most brilliant idea, so I drank yet another bottle of water and
departed with temps on the ground of 100 even. Made a climb
straight up to 7500 where the temp was still 84 degrees. Didn't
take as many readings as David, but here is what I recall:

2.5l NA RV9a GenII gearbox with MT Prop. 4800 rpm for take-off,
4600 rpm for the rest of the climb straight up to 7500msl. 100 kts
or so in the climb. 1000fpm decreasing to 650 at the top. Max
coolant temp 221 max oil 222 max gear box 213. The max temps
occurred around 5500-6000msl and dropped a degree or two on the last
1000 feet or so. After about 10 minutes at 7500 temps were at my
normal 188 for coolant 190 for oil and 195 for the gear box. I
would say the mod helps quite a bit, as I would usually decrease the
rpm on a long hot climb like this, and still be pushing 230
degrees. I still need to do the cowl exit mods, but that may wait
as I can't imagine wanting to fly in temps any hotter that these
anyway, I was sweating like crazy the entire flight.

Hopes this info helps.
Nathan Larson
N217JT RV9E 511 hours
Heading to Oshkosh on Sunday!