SEN 2627
- Sierra Cup Flyoff Notice
- Sierra Cup Results BCP
- On Accurately Verifying Electric Motor Runs
Sierra Cup Flyoff Notice
For the 2 F1B and 2 F1C sportsmen in the 10 minute early AM flyoff, you should be at the CD’s trailer on the field at 6:45 AM and the CD will direct you to the flight line
Sierra Cup Results BCP
The Sierra Cup F1B, F1C and F1P started on the Western Flight line. This was used for the first round as the westerly morning wind would have put people flying from the Northern flight line on Hollway Rd, into the pits or oil field. At 9 am the wind started switching to the North so competition was moved to the Northern flight line. The caused a delay of about one hour and the contest was reduced from 7 rounds to 6. After the regular rounds the flyoffs started with 43 out of 78 in B and 19 out of 32 in C.
Summary after two flyoffs in in F1B and F1C 2 sportsmen remain in each class. There was virtually no wind for most of the flyoff and challenging thermal conditions with spectacular climbs and drops.
During the last F1C flyoff the wind rose abruptly switching to a ‘difficult’ direction making a further evening flyoff not practical in the daylight remaining.
F1B – remaining
George Batiuk
Gilad Mark
F1C – remaining
Shannon Tolmie
Serhiy Katyba
F1P was won by Randy Secor
Here are the results
On Accurately Verifying Electric Motor Runs
By Aram Schlosberg
Free flight electric motors can’t be timed accurately by a human timer. Period.
When F1Q motor runs are timed statically, they under estimates the true motor run since the prop does not unload. (In flight, as the model speeds up, the prop’s pitch falls and the motor drains less current.) Static energy testers (SET) have the same problem.
With a weak battery that supplies less current, an EL’s signal will be delayed. And if the delay is long enough the motor will be shut down by the eTimer’s internal clock acting as a safety.
And when there is an early function – executed before the motor’s shuts down. (For example, kicking in the rudder 2 seconds before the motor run’s end.) In this case the EL could be programmed to say 90% of the model’s energy budge. The eTimer executes the early function when receiving the EL’s signal and shuts down the motor 2 seconds later. (I actually do this with my Q-B model.)
But it executing an early function based on the elapsed time since launch is done by the eTimer and it shuts down the motor when it receives the signal from the EL, then the time interval between the early function and when the motor is actually shut down is battery-specific – that is, has a random variable. A-kind-of “no two runs are identical” phenomena.
So what’s the solution?
It’s suggested that a new generation of ELs will continue to send a signal to the eTimer when their programmed amount of energy is depleted; BUT instead of recording when that happened, record when the current falls below 4-5 Amp base. (This base-current-level is required the run the eTimer and servo AFTER the motor has shut down.) The duration while the current exceeds the model’s base-current-level is the TRUE motor run and should be displayable after the flight for verification. Such a change is feasible for future ELs according to Dick Ivers.
In short, that a Q’s motor runs be the duration a model’s current is above a base-current-level once the start button was released.
Finally, a quick look at electric events without ELs (AMA A and B-electric, E36 and F1S.) Verifying their motor runs can only be done statically. ///