the testing | Paraglider Testing |
are reviews from a pilot's perspective. They are not certification tests
since I don't do any significant SIV-type maneuvers with them. I try hard to
be unbiased and accept no sponsorships or other remuneration from the
product makers nor are advertisements accepted from those being reviewed.
If you are a wing importer/seller with a wing you would like to have
reviewed, I would be happy to. Since its a lot of work and I make no money
at it, I ask the following:
- I'm more interested in smaller wings so only want to review those with
a wing loading over about 7 lbs/m². At my weight that means 25 m² or less
- Although I love soaring, my circumstance dictates more motoring and
I'm a lot more familiar with what works best for that. Consequently, I
have no interest in reviewing wings that are intended primarily for
soaring unless their sellers feel they also make good motoring wings and
other pilots have found that to be the case.
- A few wings exhibit oscillation under power. This usually has to do
with how the motor interacts with the wing and is not a big deal. So
although I may report it, you should try the wing with your motor. I've
flown 3 wings with this behavior on my Blackhawk motor and my one of my
wings did it when I flew it on a DK beat (old direct drive motor).
- If you would like me to review your wing, I ask that you pay for
shipping to and from my flight location. Please contact FootFlyer.com
You can see from the flight test sheet
that it takes some time for a full review and I can't always complete it.
Sometimes a wing is around when I don't have a tape measure, hand scales, camera or GPS
but I'll still report what I can.
Speed is measured by flying a constant altitude and using the following
method. It's best if the motor has weight shift steering although tip
steering works too (using stabilos). It must have enough oomph to fly me
level at fast trim and full speedbar.
- Set the trimmers to their slowest setting. Without using speedbar or
fly directly into the wind where it's easy to see left/right drift.
That establishes the wind direction. Let the speed stabilize and take a
GPS average for 5 seconds.
- Turn to exactly downwind and take another GPS average.
- Turn back to upwind, record the speed again (for verification). The
rest of the test is done on this heading.
- Let the trimmers out (if equipped), let it stabilize and record the
- Apply full speedbar, let it stabilize and record the speed.
You'll now have 6 speeds: upwind, downwind, and upwind all trimmed slow.
Then upwind at fast trim and upwind at fast trim with full speedbar.
Subtract the upwind speed from the downwind speed and divide it by
two--that's your windspeed and will be subtracted from your next three
speeds to get an airspeed.
This is mostly subjective but a big deal is how much brake pull it
takes, both pressure and distance, to achieve a 45° turn. For most wings
that's approximately where the tip appears to touch the horizon. Higher performance
wings tend to be longer and skinnier so their tips will be a bit lower
while still in a 45° turn.
Some wings curl the tips to pull the wing
over for a steeper turn. That also will cause a dive if not countered with
opposing brake. Higher performance wings, namely high aspect ratio models,
will generally spin easier too. I'll never get to test that on a lot of
wings because I'm not willing to get them that close to stall without
being on a dune.
When time permits (it rarely will) I'll try to quantify handling
with a pull force scale on one brake toggle on the natural turn side
(right turns for belt drive machines)..
A couple things that can tell a lot about how well a wing comes up
involves simply laying it out for a forward launch the trying to inflate
it without using the A's. Also important are whether or not the tips tend
to come up into the center and whether brakes tend to fold back a tip.
Unless the manual says otherwise (I've never seen one that does) I'll
use the center A's on split A-riser wings.
There is a lot to test and some things to measure whenever possible. A
lot of effort goes into testing machines and, although I love the flying,
it's a lot of work. Sometimes I'll only get a couple flights on a machine
that I'm trying out because of availability.
Here's a tough one. I fly a machine that averages about 130 pounds of
thrust, one that averages 95, and another that struggles to get 75 pounds of thrust. So I'm
gonna stick with using climb rate and comparison since I can't carry a
thrust tester around. Thrust tests, done at fly-ins where machines are
tested WITH THEIR HARNESSES are the only valuable data. Unfortunately that
is hard to find.
I try to do comparisons on the same wing but that's not always
possible. If different wings are being flown in side-by-side climb tests
then I'll subtract the climb rate of the less efficient (or more heavily
loaded) wing. For example, one side-by-side test involved me under a Spice
22 with a Fresh Breeze Simonini and another pilot on a U-turn Acro 17
flying a FlatTop Simonini. I out climbed him by about 100 - 150 fpm. But
he was way more heavily loaded on that wing. My power-off sink rate is
about 350 fpm and his was probably about 450 fpm so I subtract that out
which means that model FB has more thrust than that model FlatTop by
probably 5 pounds. That's essentially irrelevant. Differences in thrust
will vary within model, even on the same day and same place, by
probably 10%. So, in my opinion, differences less than 10% are
Empty weight is what we care about--weight of the motor, harness, prop,
and any accessories that come from the factory as standard. In other
words, how much it weighs ready to fly sans fuel. Of course we also have to lift
the fuel so consider that an efficient motor will let you carry less fuel.
On a 4-stroke, empty weight includes engine oil. An electric motor's fuel
is in the battery which will obviously weigh the same on landing as it
does on takeoff.
The plan is to put an accurate scale on a hard surface, weigh myself,
put the motor on my back and weigh again. I obviously need a more accurate
scale because when I tried the test several times, I got different results
(by up to 4 pounds). Given that a few pounds can mean a lot, I'm not going
to include my weight measurements until I find a better scale or method.
Two aspects will be commented on: the pilot's in-flight sound and sound
from the ground. A DB meter is almost worthless if the noise it's
detecting is not what's annoying to humans. A loud dog whistle is hardly a
bother. Go to a fly-in and listen to the loud motors. Listen to the quiet
ones. It turns out the DB meter doesn't get it in that regard. So until I
find a DB meter that matches the politician's ear, I'll stick with my
method: note which ones are quiet.