I
J
K
Fig. I: At low airspeed (during stall or on ground),
the solenoid valve lets energy drain from Potential.
Fig. J: Warning light indicates low airspeed.
Fig. K: To simulate increased drag from high angles
Try climbing as high as you can to determine the
simulator’s “service ceiling.” Be patient. It can be a
slow process. Then find your simulator’s maximum
airspeed by pushing the stick forward with the
throttle wide open. Unlike the real thing, your simulator won’t break apart when you pass the “redline.”
Periodically check the fuel gauge to be sure you
have enough to complete your flight. But note that
you can continue flying in glide mode, as long as
you have some altitude to convert to airspeed.
Photograph (Fig. K) by David Simpson
To land, back off on the throttle and push the stick
forward to keep airspeed safely above stall speed.
The altitude reading will drop. As you get closer to
the ground, ease back on the stick to slow the plane
down even further, but don’t get too close to the stall
speed or there may not be enough altitude to recover.
The goal is to stall the airplane when you’re completely out of potential energy in the form of altitude
— in other words, when you’re right over the ground.
Future Work
My current HFS has a few obvious flaws, but what
model is perfect? Here are 3 things I’d like to improve:
1. As the water level in the fuel tank drops, the
pressure into the Kinetic reservoir drops as well,
L
of attack, pushbutton valve at base of stick drains
Kinetic when the control is pulled back. Fig. L: To land
your plane, zero your airspeed at the same moment
you zero your altitude — you’re back on solid ground.
whereas in the real world, an engine can run just
as powerfully on the first gallon in the tank as on
the last. I’d like to keep the pressure consistent.
One way would be to continuously pump water
from the catch bucket back up to the fuel tank, while
monitoring the volume pumped until the sim fuel
capacity has been exhausted.
2. The size and configuration of the drag and loss-of-lift holes were not modeled for any particular
aircraft — but they could be.
3. Real-world planes weigh less, and therefore
perform better, as the flight progresses. That
could be modeled as well.
If you have thoughts or ideas, please feel free to
write me!
For videos of the Hydraulic Flight Simulator in
action, implementation details, materials and tools
lists, and information about the U.S. Civil Air Patrol,
visit hydroflightsim.net.
David Simpson ( dsimpson@hydroflightsim.net) is a private
pilot, and began building and flying model airplanes at age 11.
147 Make:
