stunthanger.com
General control line discussion => Open Forum => Topic started by: Tim Wescott on March 21, 2014, 01:48:20 PM
-
Or, how long is a string?
This should maybe go into the electric forum, but -- how much time should one budget from the moment that a model is released until the moment one has completed one's two laps after the clover?
Clearly this varies with lap time, so the opposite side of the coin (I guess) is -- what's the longest lap time that works for exactly six minutes between release and motor cutoff?
-
5.30
-
I'm at 5:40 to give me a little wiggle room.
-
I've seen it vary as much as a minute even with similar level lap times. Manuever speed and how much the airplane slows in a manuever can vary a bunch depending on weight and power. Watching quite a few flights on video slow motion is very interesting!! The answer would be prefaced on the equipment mostly.
Dave
-
Tim,
It depends a little on the lap time and line length that you use. For normal flight speed (~53mph) if you release as soon as the motor starts and you hit every maneuver with only 2 lap between you need 5 min, 10 sec. If you like to have the motor spin up all the way then release and want room for an extra lap between maneuvers now and then go with 5 - 30 sec. You will need to watch the battery capacity to make sure you have head room left. One thing that has worked for me is to do a ground amp check. Check the battery section up top to calculate the capacity needed capacity for a given amp draw. For a 4S pack I find that if I take the pack capacity and divide by 100 it gets me in the ball park for the max ground amps. For example if I have a 3300 mah pack my starting ground amp draw would be 33 amps. Adjust the prop diameter to reduce or increase load. My advise is to always start with a smaller prop, take a couple flight to get a base reading on the amount you draw out, get the base amp draw and adjust to keep 20 -25% remaining capacity at the end of the full flight.
Best, DennisT
-
Are you including the delay time after start button is pushed (if you are using a delay) and the spool-up time until motor reaches full power? As far as air time I use 6:15 on my E-Legacy on 63' lines from start of spool up to motor shutoff. I was told by a top level expert to always allow a little extra in case a dust devil comes through the circle and you have fly level for a few laps then resume (our contest site near Sacramento), or if a flock of Canadian geese rise up off the pond adjacent to our home field (Alameda) and fly through the circle, or if a migration of lace snipes moves through the flying area, distracting the pilot (your neighborhood apparently).
-
On my ship the timer sets for only the motor run the delay is set separate 20 seconds, so 5:50 total.
Best, Dennis
-
Are you including the delay time after start button is pushed (if you are using a delay) and the spool-up time until motor reaches full power? As far as air time I use 6:15 on my E-Legacy on 63' lines from start of spool up to motor shutoff. I was told by a top level expert to always allow a little extra in case a dust devil comes through the circle and you have fly level for a few laps then resume (our contest site near Sacramento), or if a flock of Canadian geese rise up off the pond adjacent to our home field (Alameda) and fly through the circle, or if a migration of lace snipes moves through the flying area, distracting the pilot (your neighborhood apparently).
No. As stated in my original question: from the time I can convince my helper to let go of the plane until the time that the motor can cut out for a landing without me losing any pattern points.
-
I adjust my fuel load to get 7 laps after the clover. I record the fuel load, rpm and laps after on every flight. That way I'm in the ball park on contest day.
-
No. As stated in my original question: from the time I can convince my helper to let go of the plane until the time that the motor can cut out for a landing without me losing any pattern points.
I have timed my planes from the time I pull the stooge chord until the wheels stop rolling and it averages out to 5 1/2 minutes. This is IC powered planes. And I know you guys can program your time with the electric doo-dads. n~
-
Since we're talking electric and programming a computer, the "E-Answer" is 5:30. That's if no problems and you don't add a little at the end to unwind your lines before landing with a few outside loops. I don't think there is any risk of an overrun with E power if your timer works properly, which even in FAI is seven minutes. Why give yourself the potential of an under-run if there is some reason why you may need a few extra laps during the sequence?
The timer doesn't know how long your helper will hold the model at full power until release, so that is another variable. You can't program in "helper indecision" so you should probably account for it in choosing a run time.
-
pattern usually completes in 5:10 with a modern piped ship flying 5.2 second laps.
Fuel measured to get 2 laps after the clover, two outside loops and 2-5 laps before shutoff. I'm typically done flying under in 6 minutes.
-
At my practice field I use 5:00. On contest day I use 5:10.
At 5.4 laps on 70' lines I get 3 laps after exiting the clover.
Why take more out of the battery than necessary when practicing?
-
There is a rough rule of thumb approach to determine the time to complete a pattern. This is based on some experience with IC engines. Whatever the time needed to start the engine and signal the release to start the takeoff roll, the number of minutes needed to complete the pattern after the signal to release for takeoff sort of works out to be to be the same as the number of seconds to complete one level lap. Or in other words, if the lap time is about 5.2 seconds, the pattern time (from takeoff release to end of the four leaf clover) will be about 5 1/4 minutes. Check it out some time.
Keith
-
Sometimes I wonder why we get all huffed up over 8 vs 7 minutes rime limits at the NATS. Neither is anywhere close to reality. H^^
-
Sometimes I wonder why we get all huffed up over 8 vs 7 minutes rime limits at the NATS. Neither is anywhere close to reality. H^^
The time we are measuring here is from release of plane to power off. To that time you have to add motor starting time (for gas motor), time to walk to handle and release, and for gas motor time to run tank out, and time to glide to landing and stop. The key item for a gas plane is the time after the pattern before shut down to stop before 7:00 minutes.
-
Sometimes I wonder why we get all huffed up over 8 vs 7 minutes rime limits at the NATS. Neither is anywhere close to reality. H^^
Balky engine + too much fuel = blown time limit.
Balky engine + too lean a needle setting = blown time limit.
Part my Intermediate year was learning engine management, and I wouldn't bet you money that I don't have an overrun at least once a year that I'm using engines.
-
Sometimes I wonder why we get all huffed up over 8 vs 7 minutes rime limits at the NATS. Neither is anywhere close to reality. H^^
Well, one way to think about this 7 vs 8 minute Time limit is to show courtesy to the judges to have the flight completed in less than 7 minutes, particularly when the wingover is normally completed at around the 6 minute mark or less, plus or minus a few laps and depending on the time required to start as well as the lap time. Not only does it show a courtesy to the judges, it speeds up the contest for all of the other officials as well as contestants AND it shows that the pilot knows and understands how to operate his equipment as in professionalism.
Keith
-
Is this some kind of preemptive strike to change the rules for some other unknown strange reason? Is this a look into the future of a new rule proposal to shorten the time limit? If so its not needed. The only thing that's changed sense the original rules were written are the people. I guess they had a better understanding back then.
-
5:30 from spool up to shut off plus 30 seconds "delay" at the beginning plus another 20-25 seconds till plane comes to a stop. I described it well over in the rules section http://stunthanger.com/smf/index.php?topic=30877.0 Look at reply number 22.