Hi Karl,
> I have been following your developments with great interest and I think
> that the end result is just plain amazing.
Thanks!
> Now, top speed is very useful for testing drag improvements, but you
> don't cruise at those speeds, do you ? When you are touring, what are
> your preferred settings regarding speed, MP, rpm etc., and exactly what
> is your fuel consumption then.
I found the sweet spot of the aircraft is with 27 inch MAP, where it
usually cruises with a speed somewhere between 120 and 130 KIAS,
depending on C of G and some other obscure factors. Fuel consumption
used to be 16 to 17 liters per hour, but I have observed this year that
the fuel consumption has increased to 18 liters per hour. Maybe the
carbs need an overhaul or so.
RPM is usually between 4800 and 5000 RPM, this feels best for the
engine. I have a two blade prop and at lower RPM's it feels less smooth.
Of course actual settings depend on various circumstances. With a strong
head wind we usually advance the throttle a bit, with a tail wind we
enjoy the lower fuel consumption of a lower power setting. We fly 90% of
our cruising with power between 26 and 28 inch.
With higher power settings the fuel consumption goes up faster than the
gain in speed. Other than in a car, a higher speed doesn't give any
other feeling than a lower speed, it just gives the same sensation. One
hour flying is still one hour flying. On a 3-hour trip I rather enjoy an
additional 10 minutes flying and have a free meal than just cranking up
the fuel consumption, paying more for less fun. AVGAS can be close to 3
Euro's per liter over here, so saving 10 liters on a trip can save
enough money to have a dinner for two! ;-) I love telling friends that
flying there isn't more expensive than getting there by car.
> If the rest of us mortals wanted to implement some of your changes
> without too much expense, what would you recommend ?
There isn't much money involved actually. The radiator costs about 300
Euro's, the heat exchanger a bit less. You can do without the heat
exchanger, I have been flying one summer with the stock oil radiator fed
by a 2" Scat tube via a wedge diffuser. Apart from the long warm up time
it was quite an improvement over the tandem setup. Best thing to do is
to scrap the stock coolant radiator, dog house, duct and associated
hardware and just install a thin radiator in a 45 degree angle in front
of the exhaust and turbo.
The main hurdle here is to shape a new underside of the cowling. You
have to be brave enough to cut the dog house away, and then insert a
block of blue foam and start cutting, rasping, sanding until you have
the shape you desire. Anyone who wants to make a mold out of my cowling
is welcome to do so, provided I'm allowed to use that mold to make a new
light weight carbon cowling for myself. ;-)
BTW I'm not the only one who devised something like this. See the
attached picture. This is another configuration with a thin radiator in
a 45 degree angle, although it lacks a cowl flap and heat exchanger for
the oil. (Oil is cooled by a radiator, fed by a NASA duct on the port
side, you can see it on the picture). Also this owner claims very good
results with his setup on his 914 engine. The key really is to use a
thin radiator and mount it at the belly so the "used" air can take the
heat of the exhaust with it, and enjoy the benefits of a very sleek
cowling, excellent cooling, low pressure losses, and minimal cooling drag.
Anyway, my cooling design is not an exclusive invention of me but the
combination of ideas and experiments of multiple Europa owners who
believed that the cooling of the Europa could be improved other than by
using draggy brute force solutions.
> What is the part number for the
> heat exchanger and exactly where did you install it ?
See picture, taken from under the engine. The heat exchanger is mounted
behind the engine. This was the first setup, with the stock coolant
radiator, hence the configuration of the coolant hoses pointing
downwards. In the current design the hose routing has been changed to
accomodate for the thin belly radiator.
If you really want to go this way, contact me privately for more info.
One caveat though: this heat exchanger has very thin canals and is not
compatible with Evans coolant due to its viscosity. I use it with 50/50
without problems.
> It also had a very
> small (8AH?) battery.
I also have a small 8Ah battery, never needed anything more than that.
But I have a second alternator (mounted on the vaccuum pad) so I don't
need the battery as a backup during flight, I just need it for starting.
Frans
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