Earthstar Forums

Yesterday, I flew for the third time with the new cowl, motor mount
fairings, prop and spinner. Flew for 50 minutes, 24% charge remaining.
Sample size is still too small to establish solid averages, but here are
some first impressions (compared to last season):
1. stall speed went from 47 mph to 42 (no flaps)
2. minimum required power to keep altitude went from 10.5 to 8.5 kW (but
speed dropped from 55 to 52 mph)
3. in 50 minutes at various power settings, starting in OAT≈47F, motor temp
settled in at 140F. After a 2-minute cruise climb at 20 kW, motor temp
reached 165F. Battery temp went from 55F to 86F. Controller never got past
63F.
4. slightly less tendency to yaw (less rudder work)
5. cabin noise level dropped. More whine than rattle now.

I also flew in CUSTOM Mode, which I had set up for max speed, max
acceleration, and max regen. At one point while descending I saw -0.5 kW
power - regen is working, but likely not as well as with a motorcycle.

I don't know how hot I can run the motor. Not specified in the Zero
Motorcycles manual, and no info on the Zero forum. I know my motor can run
hotter than the 2013 version, and I know the controller will limit power to
keep temps under control. But no signs of intervention up to 165F - I may
need to fly at high power on a warm day to find the point at which the
controller steps in, and to be sure there is still enough cooling. If not,
I may have to open the outlet a bit, or, more likely, provide better inlets
(not much gap around the controller).

Attached are 20 photos, for a total of approx 6 MB. Let me know if your
email browser complains.

Some comments on the photos:

#10...13: I built my fairings and cowl in my shop, without the wing (which
I leave at the airport). I had previously built a wing root “mockup”, which
I thought was a reasonably close copy of the real thing. But after taking
the fuselage out to the airport and installing the wing, my fairings and
cow did not fit well at all – see photo 14. The trailing edge of the wing
fillers was almost .75” higher than expected. I was eventually able to
install the fairings high enough to push against the wing, via some weather
stripping. The fairings are pretty stiff after they are installed, and I
don’t think I will need fasteners. That will allow me to simply lift the
wing off the fairings.

The cowl needed major alterations to fit, but I got it to work pretty well
now. Gap between spinner disk and cowl is about ¼” – this is close to the
amount the prop and motor may move forward when applying full power. The
rubber mounts could probably be a little stiffer, since we don’t get much
vibration from the motor, only the prop.

I wanted the cowl removable in the field, without having to remove the
prop. I equipped the lower end plate with 10 nut plates (8-32), flush
riveted (see photo 20). Where this plate meets the upper portion, I made
the sheet metal overlap a bit – seems to work fine. Along the sides I used
piano hinges, which can be pulled out the back. The wing-side hinges are
mounted on filler ribs until these ribs merge with the sides of the wing
filler. For the front, I fabricated a lip under which the cowl slips. See
photo 22. This still leaves the rear wing bolts accessible once the cowl is
removed. On the left side, the piano hinge had to continue on top to make
room for the motor cables (photo 23). I have marked the hinge pins so that
I can see if they start to work themselves out (no sign of that after over
an hour of flying). But I do plan to come up with a simple retention
feature. The lips of the cowl push against the top of the filler ribs,
leaving a fairly clean shape with a minimum of exposed rivet heads. There
are no sheet metal screws that can strip after a few installs, come out and
go through the prop.

I bought a couple LED “strobes” from Aircraft Spruce. One is installed on
the belly, the other on top of the cowl. There is a coax connector under
the cowl. These “strobes” are pathetic – sometimes I don’t even notice them
from just a few feet away. This was my 3rd attempt to use LED strobes. I
may have to bite the bullet and get some real Xenon strobes. Different
subject…

Photo 30: Mark’s tuft testing on Richard’s Bravo showed that the front
fairing above the windshield – the brow fairing - gets lifted by the low
pressure on top of the wing and causes turbulence all the way back to the
cowl. For two seasons now, I have had a nutplate and screw at the very top,
and 2 additional bolts for which I tapped holes through the wing hold-down
brackets. My brow fairing is covered with the same Oratex silver I have on
the wing, and on the inside I have copper foil (aluminum would have worked,
too), to provide a better ground plane for the radio antenna. The weather
stripping between wing and fairing increases turbulence, but is required to
keep rain out; maybe it could be a little thinner. If I had an English
wheel...

The cowl and fairings look good and streamlined, especially with the red
prop and spinner. I want to fill a few fillets where the fairings meet the
shell, and I may eventually opt to paint at least the fairings red. But
those are really just cosmetic enhancements, and they can wait till winter.

Time to go fly!
Martin

Good timing. The cowling the next thing I will be working on.


Temperature limits can be found using the diagnostic plug. If you go to https://zeromanual.com/wiki/MBB_Console#Settings https://zeromanual.com/wiki/MBB_Console#Settings , search for expand then click on it. This has numbers for someone’s 2016 bike. It shows the motor stage 1 (warning) temperature is 100 C and stage 2 (power cutback) happens at 145 C ( 293 F). Lots of room. The corresponding controller temperatures are 70 and 75 C.


I too have had disappointing experiences with strobe lights. I was unimoressed with Aveo Powerburst units. No one ever saw me. For my eGull, I bought a pair of Aviolights Red Eyes. These use twice as much power and I believe red is easier to see in the daylight. I should be flying in a about a month and will report on their effectiveness.

Hi Martin
Looks good!
It looks like your exit vent under the motor is a little bit smaller than on Richard Steeves cowling.
Have you climbed out in sport mode at full throttle? In Richards I could run it for a minute at 40 kw, before the high motor temp cut back engages.
I think it is just under 100 C or 212 F.

At 20 kw, output it should not get hot enough to triggered the motor temp limit.
Can you tuft test it?

Happy Flying,
Mark

Sent from our iPhone

Thank you Ray!


Happy Flying,
Mark

Sent from our iPhone

My documents from Zero rate my motor at 22.1 kW continuous.

Are there plans for an eGull or does everyone do it their own way?

Yes, that 22.1 kw sounds right.
I was just being conservative.

Happy Flying,
Mark

Sent from our iPhone

Yes, thank you, Ray! Interesting link.
I flew yesterday at higher power levels and shortly had the motor temp at
175F (80C). This means I had a 37F/20C margin before the first warning. But
it was relatively cold. Will have to keep an eye on that when we hit summer
temperatures. No worries for now.
22.1 kW continuous sounds great - certainly enough for cruise climb, and
even enough for a go-around. And I suspect we have better cooling than the
motorcycles, with that big fan pulling cold air through the cowl.

I thought Mark would chime in here.
Joel, all Gulls come in kit form, almost everything included except paint
and instruments. Even the control cables come in the right length with all
thimbles etc swaged. The propulsion system is extra, of course, and every
builder will have his/her preferences - a la carte, brand new motorcycle,
or (most economical) a recent wreck. The Aerolux prop that Mark suggests
works well, looks good, and is reasonably priced.
Even though steel tube cage, wing spar / D-cell, fiberglass shell all come
as major components, there is still plenty of work required to put it all
together, and there will be variations that are left to the builder to
finalize. By the time the fuselage and wing come together, variations can
be large enough to require "customization". That is why the cowl kit comes
in pieces and requires fitting.

Thanks Martin for the detail.