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Archive for July, 2016
Posted by phil alvirez | Jul 29, 2016 @ 06:06 PM | 7,413 Views
or should be the ecstacy and the agony? let me explain and you will decide:
today was another of those wonderful days when the weather cooperated at its full extent. no wind, puffy clouds, no moskitos, so i could fly my 2 meters sailplanes. so i began to fly my planes. the light 1 (650 gr) got light thermals at low level and thanks to the vario catched them effortlessly and remained there until i decided it was enough and turned the vario off. but then the plane didnt descend. kept sailing back and forth for a long time. ecstacy!
then the standard (860 gr) went up. this time climbed higher. all seemed o k. thermaling great. ecstacy again!
then i got enough again so again, turned the vario off thermaling. but as i changed the vario to height (tells the height) i noticed that it was climbing at an alarming rate. soon was above 400 meters, and couldnt bring it down! spin, dive, whatever, but no. i have to be careful because if i bring it down too fast it may fold the wings, so the only thing i could do at that height was to listen to the voice how fast it was descending. it took a long and agonizing time to be at a safe height. then i just landed it and went home. no more fun for the day.
so, was the agony and the ecstacy or the other way around?

Posted by phil alvirez | Jul 24, 2016 @ 06:25 AM | 7,195 Views
just got this answer from a fellow to whom i asked something:
" I'm a bit of a practical guy when it comes to modeling. If it works then that's good enough for me and if it works well then that's a even better:-) It's a shame people feel like they cant contribute in an open forum. For me I like to hear as many options as possible. That way you can consider all of them and go with what is best for you"
it sounds so good that i just cant resist to show it. i couldnt agree more.
Posted by phil alvirez | Jul 19, 2016 @ 02:25 PM | 7,211 Views
weather vane effect on sailplanes

if a plane has too much side area behind the cg it may have the tendency to point at the wind and resist going any other way.
just like a weather vane. resisting to change direction.
Frank Zaic mentioned a method to keep this in balance by a very simple method without calculations. he called it center of lateral area.
from cardboard he cut a profile of the model showing all the components viewed from the side, including the side of the wing with the dihedral. then pinned it at the desired cg and saw if it balanced. i tried it with all my models and it worked.

if any1 has some experience with this, please bring it.
please only comments polite, positive and to the point.

i started a thread on the issue here: