I hope you had the p-port installed. If not I hope your are using a turbo
charger.
A Wheeler Express is going to need 250 HP.
Paul Lamar
It is a P-port, and I am going to use the turbo. It may work out that I
fly my 40 hours off, dont like the 13b p-port and go with a 20b turbo. It
looks like the biggest issue then would be W/B. I have that figured out
too- a pair of battery wires are run to the rear baggage compartment from
the attachments in the inside of the FW. Right now they are just laying
there, but if I decide to change out for the 20B the math indicates that I
will need to move my battery aft. Shouldn't take more than an hour or so
more than replacing a battery.
I have talked to several people with wheelers both by phone and internet,
and it seems that an IO 360 (210hp) gives a cruise within 5 knots of an
IO540, but with a longer takeoff roll and slightly less climb. However, the
360 burns 15% less fuel. The 540s seem to burn around 13 to 14 GPH at 160
knots, and the 360s are reported at closer to 10 to 11 at 155. Much of my
flying is to the Bahamas, where there are many airports, and few places to
get fuel. Fuel burn is a big issue. Also, their mogas is brought in by
tanker in much smaller quantities than here, and contamination is also an
issue. My plane holds 80 gallons, and I need to make the best use of it.
There is a video online of a Wheeler in testing for vortex generators. This
plane reportedly has the IO 320 rated at 200 hp. He reports flights at 150
knots cruise on 10 gph in the video.
Attached is a page from the POH and builders manual giving the limitations
on the engine as designed. My plan was for 300 hp at T/O and maintain 250
in cruise. I plan to fly it just like the Viking- 7500 RPM and 300 HP for 5
mins takeoff, 6000 RPM cruise. My viking had an IO520D 300 HP N/A. The 300
on T/O was nice, and she cruised at 23 squared at 160 knots. Her empty
weight should be 300 lbs more than the Wheeler (2300 was the Viking EW).
Every Wheeler builder that I have talked to so far came in under 2000 lbs
with a nice plane. That is my goal.
One of my bigger issues at the moment is the thrust line- as designed the
thrust line puts the engine about 1 inch below the cowl which precludes the
installation of intake runners over the top like most of you do. I have a
little bit of a reservation with lowering the thrust line 3 inches to make
it work with the runners on top. I am thinking that I will need to run the
intake runners around the firewall side, or do it like Tracy and place a
plenum on the intake side and not use the runners at all. It looks like
option 2 is the most likely at this point. I know that the runners are
important N/A, but I think the positive pressure from the turbo would
offset most of the tuning issues with the intake runners.
Kevin Alderman
It all depended on BSFC, altitude and air speed. The lower the airspeed
the lower
the HP and maybe the fuel burn depending on the BSFC at that engine RPM
and throttle
opening. Down to a point. That point is maximum rate of climb speed Vy.
I think it is about 104 Kts for the Wheeler.
BSFC is pounds of fuel burned per HP generated.
Take this chart for example. This BSFC turbo 2 rotor has a best BSFC at
4000 RPM and
105 HP. Assume the turbo 3 rotor is 150 HP under the same conditions.
These BSFC
numbers are hard to come by so it is best to have a torque meter in your
gearbox.
Point 46 is excellent for a rotary.
Now how can you slow the airplane and set the power to get minimum HP
requirements?
Your target is best BSFC at 4000 RPM so you need a variable pitch prop.
Increase the
pitch unill the RPM comes down where you want it while the throttle is WOT.
It may be a different number for a turbo p-port.
It is going to take a lot of experiments on your part with a GPS to
discover the best
MPG.
This a long and complicated subject. I highly recommend getting Donald
Crawford's
book on the subject. A PRACTICAL GUIDE to AIRPLANE PERFORMANCE and DESIGN.
310 375 9227. Ask for his help. Tell him I sent you.
Paul Lamar
normal asperated 0-360 at 75 % power burns 10 gal/hour. the 0-540 at 65 %
power burns about 12.5 gal per hour. it burns 14 gal/hour at 75 % power. i
still have the rotary eng and new gear box for sale in middle Georgia. eng
was rebuilt by Bruce turintine. i may not have spelled his name correct.
my phone # 478-922-1428 cell is 478-335-6835.
tom kimsey a&p ,atp, cfi...
Lets look at the Lyc O-360 first.
Given 75% of 180 HP that is 135 HP. Given 10 gallons an hour at 6.25 pounds per
gallon that is 62.5 pounds of fuel per hour. That translates to a BSFC of
62.5/ 135 or .46 BSFC. A p-port rotary is .47 NA or .46 turbo.
The Lyc O-540 is 260 HP so 75% power is 195 HP.
14 gallons an hour is 87.5 pounds per hour. That is a BSFC of 87.5/195 or .45 BSFC.
Slightly less than a 3 rotor at .47 NA.
My Cont. O-470 in my C182 BSFC is .52.
Here are charts for a p-port 4 rotor NA and a Cont. O-470 NA.
To get a more exact measurement of BSFC the temperature of the gasoline must be
known. Colder gasoline is heavier per gallon at altitude. That is why BSFC is used
instead of gallons per hour when rating engines on fuel burn.
Tom, What is the gear ratio in that gear box you have?
Paul Lamar
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