Ed wrote:
Its a real airplane now {:>)!!. You know you are
going to have to take some time at some point to give us all a rundown on your
first 40 hours. I suspect that due to the lack of messages from you to the
contrary that it must have been mostly smooth going.
Some of the usual delays getting going.
Some surprises on weight and balance; delays waiting for workable
insurance quote; delays waiting for test pilot since the insurance company
wouldn’t cover me in my plane, etc. Other than that, I guess three
main issues:
The most time consuming, and on-going,
issue has been with the EC2. I realize that the unit works well on Tracy’s and similar
installations, but it did not accommodate my combination of composite airplane,
3-rotor engine, and my electrical system design. After lots of checking and changes, some of which helped, but
didn’t solve the problem; we finally added additional filtering on the
circuit board; and that problem went away.
In the process we identified some
additional issues arising from the way in which the 2-rotor version was adapted
to the 3-rotor. This has been resolved by adding Schottky diodes in the
circuits to the injectors to prevent partial pulses going to the set of injectors
turned off by staging, or by the disable switches.
There are two remaining issues.
Controller “A” works fine on the ground, but the mixture gets
progressively leaner as altitude is increased. By 6000 ft it runs out of manual
adjustment, and it has to be switched to controller “B”, which
works just fine. Both controllers read the MAP from the same line via a
‘T’. Very mysterious. We are replacing the pressure sensor on
A on the outside chance that will solve the problem, even though the measured
output from the A and B sensors are the same when the unit is powered up (out
of the plane) at different altitudes (measured at 1400’ and 5300’).
The other is that there is something
strange about the timing. At low power things appear fine; switching off leading
ignition has more effect than switching off trailing, as expected. At
operating power levels, however; switching off leading has almost no noticeable
effect; whereas switching off trailing drops the rpm by 400+ rpm – which
suggests that the timing is very late. Yet advancing the timing via mode
8 does not make any improvement. What is wrong with this picture?
It is possible that the added filters caused a delay in the timing, although
analysis suggests the effect would be small. Why doesn’t advancing
the timing improve the power? Is there a timing change to one set of coils
associated with disabling the other? We are removing the filtering
capacitors from the ignition circuits as a test to see what the effect is.
Tracy has been cooperative and as helpful as can be expected throughout
this process, but we are at opposite ends of the country (FL and CA).
Fortunately my son is expert in this field, and has been great help;
although he is in CO, still far away.
Other than that the things that come to
mind are that I needed to make some small adjustments on the incidence angles
of the wings and the canard; and the marginally high oil temps that I have
mentioned here recently. As soon as the EC2 is back in, I expect to due
some measurements and tests to remedy that issue.
Have a happy 4th!!
Al
P.S. I’ve attached a photo of my
plane taken at a recent local air show. It’s amazing how much
attention an unusual airplane with an unusual engine attracts; at even a small
air show.