RE: Europa-List: Re: Contact detail & Help

[Bud Yerly <budyerly@msn.com>]

Lovely design...
However=2C my comments are based on an installation that is stock.  Takes 4
0 hours from openning the box to engine fully installed and ready for start
 and is reapeatable with only the parts in the box.

Esthetics aside=2C the dog box works but can be improved.
Many do not care to have any auto systems such as heat exchangers which may
 malfunction.
I do 146 at 5500/34 with a stock cowl.  
By all means=2C an extra hundred hours and cost will get you those extra 9 
knots.    It just costs money and time.

The airplane is 20=2C000 compromises flying in close formation....Choose yo
ur changes wisely.  

You have obviously enjoyed and profited from your changes.  Congrats.

Bud Yerly Custom Flight Creations=2C Inc. www.customflightcreations.com (81
3) 653-4989


> Date: Wed=2C 20 Jun 2012 14:04:55 +0200
> From: frans@privatepilots.nl
> To: europa-list@matronics.com
> Subject: Re: Europa-List: Re: Contact detail & Help
> 
> On 06/10/2012 06:21 AM=2C Bud Yerly wrote:
> 
> > If I do say so myself=2C I never have cooling issues in Florida at 95
> > degree summer days using 50/50 Anitifreeze. Judging by the calls and
> > email success stories=2C these simple techniques work pretty much world
 wide.
> 
> Although your solution might indeed work world wide it is less suitable
> for Europeans.
> 
> There are a few reasons for this:
> 1) Your solution is focussed on more cooling air flow. Unfortunately
> more cooling air also means more cooling drag. More cooling drag means
> that higher power settings are required to achieve a desired cruise
> speed. Although that might not be significant for those living in a part
> of the world where fuel prices are only a fraction from what it is here
=2C
> for many of us here the fuel price is by far the largest cost involved
> with flying our Europa's.
> 
> In another posting you wrote:
> "135 with the old pants at 5500/34 inches at 1000 MSL=2C"
> "His trigear only goes 130 at max cruise."
> 
> I do 130 with 27"=2C about 155 with 34". This is a heavy hi-top tri-gear.
> Although I selected a very efficient prop and have Fred Kleins wing root
> fairings=2C I believe that a large portion of the reduction in drag is
> achieved by my modified cooling system.
> 
> 2) Climate. I believe that in your area the weather is somewhat more
> constant than it is here. This month I have been flying in cruise mode
> in freezing temperature conditions (high altitude in Norway) and in
> prolonged full power climbs with 35C OAT (Croatia). Unless you use
> thermostats you can't achieve constant temperatures in all conditions.
> 
> After numerous experiments this is what I have learned:
> 0) Cooling drag is the main drag of modern efficient airplanes. Imagine
> the air swirling around in the cowling=2C colliding in all kind of
> obstacles=2C and flowing over tubular objects (worst airodynamic shape
> possible) and finally leaving the airplane in the wrong direction and
> with the wrong speed...
> 1) The Rotax engine is for 95% liquid (oil=2C coolant) cooled. Forget
> about airflow over the engine=2C apart from the cylinder walls no cooling
> air is needed at all. Sure you can compensate for a poor liquid cooling
> with air flow=2C but it is extremely inefficient. Once you have the liqui
d
> cooling working correctly=2C you can close off all holes. That's right=2C
> ALL holes. This includes the two "eye's". the gills=2C the naca inlets=2C
> the nose wheel opening=2C everything. There is only one small opening
> needed to connect the Rotax shroud for cylinder wall cooling.
> 2) The main problem in the stock setup is the radiator. The stock
> radiator is too thick (not even to mention the tandem design). The
> pressure difference required to maintain enough air flow is too large=2C
> and you need very large openings to keep enough air flowing. I have
> tried many carefully designed diffusers but I never got the stock
> radiator working sufficient enough for prolonged full power climbs in
> hot weather.
> 3) Use an oil to water heat exchanger. This means that you have to focus
> on the air flow of only one radiator=2C and also don't need an oil
> thermostat and still have superfast warm-up times.
> 4) Get away with the entire "dog house". It is ugly and it serves no
> purpose.
> 5) Use an adjustable cowl flap to control engine temperatures.
> 6) Reroute the exhaust so the cowl opening points to the rear. I tried
> to build an exhaust augmentor but I'm not sure if it really works. In
> any case=2C the cowling air escaping around the exhaust opening flows in
> the correct direction and doesn't upset the air stream.
> 
> So. what I'm using now is a thin radiator=2C mounted flush with the
> underside of the cowling. (Custom made=2C 300 Euro's). It is slanted so i
t
> follows the shape of the cowling. Because of the angle the horizontal
> frontal area is very small=2C you can say it forms a natural diffuser.
> Flow is controlled by an exit cowl flap. If the air flow is restricted
> by the cowl flap=2C the air in front of the radiator even doesn't "see"
> the radiator=2C the air flows over the surface and follows the shape of
> the cowling as if the radiator doesn't exist at all.
> The air leaving the radiator is recycled because it flows under the
> engine=2C taking the heat of exhaust and turbo with it on its way out. No
> separate openings for these items are necessary.
> The coolant is also used to cool (or heat!) the oil via a heat
> exchanger. Apart from the heat-up time=2C the oil temperature is always 5
C
> higher than the coolant temperature=2C which I consider to be perfect. I
> keep the water at 105C and the oil at 110C in all conditions. This is
> the best for the engine and the efficiency.
> For cylinder cooling you can use the standard Rotax shroud with the
> opening under the propeller. I made my own shroud because of the vaccuum
> pad alternator which prevents the use of the standard shroud=2C but the
> idea is similar.
> 
> After one year of using this=2C I can state the following results:
> 1) Adequate cooling in ALL conditions. I have excecuted a full power
> climb from 0ft to FL095 at 80 knots in an inversion layer with a OAT of
> 35C for most of the trajectory=2C with the water temp not exceeding 110C
> and the oil not exceeding 120C. This was with the cowl flap not yet
> fully open. Although not yet tested=2C I'm convinced that the cooling
> would work ok in OAT's of 45C as well.
> 2) In cruise the cowl flap is typically only half an inch open=3B i.e. it
> protrudes only a half inch below the belly of the airplane. Compare that
> with the huge tunnelexit of the stock XS design!
> 3) Unlimited ground operations=2C even in very hot weather.
> 4) Superfast heat-up times. 5 minutes is even in the winter sufficient
> to get the oil temp far enough up into the yellow arc to perform a take o
ff.
> 5) Low cowling temperatures=2C despite the lack of ventilation.
> Temperatures don't exceed 60C=2C except briefly after engine shut off. In
> hot weather I open the oil tank access door after landing for a few
> minutes to let the hot air out.
> 6) Weight savings. I have not weighed the difference=2C but I'm sure the
> flat radiator and heat exchanger is lighter than the two stock radiators
> and tunnel hard ware.
> 
> About the picture:
> This was the unfinished design. The final version is even smoother.
> The only exit opening here is the proptrusion of the "tunnel" against
> the belly of the fuselage. The nose wheel opening is sealed off and
> flush with the belly. The cowl flap can be extended further but this is
> the typical cruise setting. Quite a difference compared to the stock
> tunnel=2C eh?
> 
> In addition of the rectangular radiator opening I have two round inlets.
> The one on the starboard side serves the intercooler for the turbo (via
> a wedge diffuser and butterfly valve). You don't need this inlet if you
> don't have an intercooler. The opening on the port side connects to the
> cylinder wall shrouds. You could use the standard Rotax shroud with the
> opening below the prop instead=2C but I made a round inlet on the port
> side to maintain the symmetry. In most setups you can ommit these round
> inlets. That would be an even cleaner nose!
> The starboard inlet also facilitates the engine air intake. The port
> inlet also connects to a very small auxilliary oil radiator. Without
> this radiator the water-oil delta T was 10C=2C and with the extra radiato
r
> I got my desired delta T of 5C. It is not really needed if you are
> satisfied with the standard delta T.
> On the top of the firewall you see a small servo=2C a similar model as th
e
> vertical trim servo. This servo connects via a rod to the cowl flap. The
> cowl flap hinges close to the radiator so even when it is fully open the
> angle is very low. A simple but very efficent mechanism!
> 
> The front exhaust elbows are wrapped to save the cowling which is very
> close.
> 
> If there is enough interest in this subject=2C I'm willing to write an
> article about it. There is a lot of testing=2C reading=2C thinking=2C and
> learning from failures behind this design.
> Although I have been flying a year with it now=2C I have only recently
> been able to test it in very hot and demanding conditions during our
> just finished round trip in Corsica=2C Italy and Croatia and overflying
> the Alps twice.
> 
> More about that trip later.
> 
> Frans
>