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Steve,
I personally would not like to see things exceed 200F Max for WOT cruise
for any extended time. Your temps do seem a bit high to me for 55% power.
I think you can do better. My ideal is 180F for both oil and coolant - that
is just my personal preference, not to say there is anything magical about
it or that problems will happen if you exceed that. But, I just would not
feel comfortable (that all important comfort zone {:>)) with temps exceeding
200F for long periods of time. I think 200F is a reasonable boundary - but,
that is just my opinion. others will have a different and equally valid
viewpoint.
Ed
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message ----- From: "Steve Brooks" <steve@tsisp.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, July 14, 2004 3:19 PM
Subject: [FlyRotary] Re: New Scoop
Ed and John,
I understand that if I have adequate cooling at cruise, it will not enable
me to do an extended climb while keeping temperatures down. At his point,
I
seem to have enough cooling to allow me to do a reduced power (55% or so)
cruise. And that is with temperatures toward the upper end of the scale.
If I can get a 75% power cruise with oil temperature of 200-210 and
coolant
of 190-200, I'll be happy. I need to improve my cooling temperatures by a
good 10-15 degrees to accomplish that.
Is that a reasonable objective, or am I trying to hit a target that is too
low ? It seems to me that 217 oil and 200 coolant is a little on the high
side. And that is at about 55% power.
If my objectives aren't right, it would be really easy to just raise the
target. In fact, it would make my day.
Steve
-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Ed Anderson
Sent: Wednesday, July 14, 2004 2:43 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: New Scoop
> Sorry to harp on this Steve. I just have a feeling that you're working
hard
> to get the temps lower than they really need to be. If you want minimum
drag
> at cruise, then the temps SHOULD be marginal on a hot day take off and
> climb. So... get the gear up and back off the throttle till you get in
> cooler air at cruise speeds. If necessary give it a rest half way up, or
use
> the technique of doing a long approach to cool off before climbing that
> someone described. If it'll cool ok at full power at cruise height, then
> you're in good shape. My 2c.
>
> John
>
Steve, I have to agree with John on his main point. Any cooling system is
going to be a compromise. If you design and tailored your cooling system
for cooling in a steep climb on a hot day, you will have excessive cooling
capacity at cruise (read - more cooling drag) than is necessary. On the
other hand if you do optimize for cooling at cruise (min cooling drag)
which
is the way a lot of Canard types do as that is one of the reasons for
their
choice of aircraft type - high cruise speed, then you will be somewhat
short
of cooling capacity needed for take-off/climb. Things like cowl flaps can
help in some cases, but like everything else with an aircraft has benefits
and draw backs - its all a flying compromise.
So as suggested you can moderate power and/or airspeed during the climb
portion to get through that heat gauntlet and then be set up for lowest
cooling drag at cruise.
Also, keep in mind, you are probably flying in the hottest time of the
year,
so if it will cool adequately now, it will be fine the rest of the time.
However, if that does not fit with your comfort zone, then you will simple
need to keep plugging away until you get the conditions you are
comfortable
with.
Ed Anderson
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