phil alvirez's blog View Details
Posted by phil alvirez | Jul 29, 2016 @ 06:06 PM | 5,407 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 | 5,243 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 | 5,244 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:
Posted by phil alvirez | Jun 21, 2016 @ 08:38 AM | 5,507 Views
a child asked his grampa: what is better: to be a dreamer, or to be a realistic?
and the grampa answered: well, could be that you can be both:
giants walk with their heads in the clouds, and their feet on the ground.
so, you can be a giant. it is up to you.
Posted by phil alvirez | Jun 18, 2016 @ 12:59 PM | 5,631 Views
Oscar Wilde said that "the only thing worse that not getting what you want, is getting it".
i never thought much about it because i thought it was 1 of his jokes.
that is, until today.
weather good, flew some of my new 2 meters sailplanes for calm for evaluation, and when the wind began to blow, i pulled 1 for windy weather, that has the vario that sends tones or tells the height.
tried to find a thermal but nothing. climbed 3 times to 200 meters (some 640 ft). the sky had just a few thin strips like veils. not the best conditions for thermals i know. the plane didnt sink, but no beeps.
i sure wanted thermals.
and then the vario began to sing. and up she went. up and up. 200 meters, 240, 300... then i began to worry. the plane looked smaller and smaller even if i did nothing. so i moved away, but no matter where, the vario kept telling higher. tried to trim it down. then dive. then the wings began to flutter. so dont put so much down. eventually began to drop. 300, 270, and so on. took over 10 minutes to land. by then i didnt want to fly anymore. i kept telling to myself: so you wanted thermals, didnt you? the flight was over 30 minutes.
so think carefully what you want: the gods of the air may be watching and decide to please you.
Posted by phil alvirez | Jun 13, 2016 @ 10:54 PM | 5,858 Views
recently purchased 2 pods and booms from here:

this is the story:
i contacted them about certain pods, and asked if they could use 28 mm motors and they said yes.
so i ordered them.
but when trying to install a 28 mm motor it didnt turn due to the inside too small. the motors i use are outrunners with the wires coming from the front.
see examples:
i tried to remove plastic but to no avail.
then cut openings at the sides to let the wires: still not enough on 1 of them. so i contacted them but they said that as i did not specify for which motor i needed the pods, they could not replace them.

so if any1 wants to buy anything from them, you need to be specific on what motor are you going to use, and include link to the product so you will not find yourself in my situation.

but still i think that when i asked if these pods were good for 28 mm motors and they said yes, they should add: "but not for motors with the wires coming from the front". then i would not buy them.
the pods are very good quality still.
end of the story
Posted by phil alvirez | Jun 12, 2016 @ 09:03 AM | 5,124 Views
since i remember, i have been fascinated with art and technology. went into tech by need but still liked art. now i can practice both, with my model airplanes, and with painting. when i got into painting i realized that as there was so much to learn in order to achieve what i wanted, i had to concentrate on it, so i quit planes for several years. but now i understand that painting is pasive; more like meditation, and feel like as if i were in the painting am doing, and i spend way more time just watching the paint than painting. this is great for me for relaxing, but does not help to keep my brains active. on the other hand, planes do. designing, building, requires an effort to understand all kind of problems and find the best solution. and flying means action. instant reactions constantly. facing the problem of keeping track of how the plane is flying; searching for a thermal; making sure that the plane does not drift away too far... and landing, with the turbulence increasing near the ground, needs all my concentration and fast reactions. it is fun, but dinamic fun! so i have reached the point where that, even if both are extreme opposites, practicing both gives me a balance that helps me feel young and alive.
Posted by phil alvirez | May 27, 2016 @ 08:41 AM | 5,306 Views
am in the process of evaluating lifting stab on 2 meters sailplanes. my goal is to use them for thermaling. not competition; to be able to stay up longer with less effort.
but above all, if it is easier to detect thermals and if a plane can be trimmed so if it senses a thermal stays there, like the free flight planes do.
also, i am trying to stablish a comparison: how a lifting stab influences the flight? stability? under power? does it help make the airplane more thermal efficient? easier to detect thermals? does it increase drag too much?
all of this will be tested in a future.
if you are interested, keep looking into this post. will be updating it at the end.
r/c models of all kinds use flat or symmetrical stabs that do not generate lift at zero degrees of angle of attack.
in ancient times, guys that flew free flight duration began using flat stabs. until some1 'discovered' lifting stabs, and from then on, all the planes use it. even to this day the indoor free flight power (rubber) use them. all of them.
there was a guy who collected plans from all over the world, together with comments of their designers, and published them. even wrote a detailed study and showed it on his books of 1951/52 (pages 5 to 20), and 1953 (pages 3 to 18). his name is Frank Zaic, and all of this was widely discussed and used by everybody-including all the experts and those who won all the competition for many years.
these books still can be reached by google.
...Continue Reading
Posted by phil alvirez | May 11, 2016 @ 09:41 AM | 5,318 Views
yesterday when i looked from my window at the trees nearby checking the wind, i noticed some movement on the grass. it was covered with yellow flowers, but some seemed to be in motion. so watching more closely i saw 2 canaries: 1 with the head and wings of dark color, the rest bright canary yellow. the other with just a few dark feathers so it was mostly yellow. nice sight. they were picking something (seeds?). then the darker found a puddle where took a bath. funny the way they do that. suddenly both took off. i never saw canaries flying free, only in cages. and with winter so cold here this was the last place i could imagine seeing them. perhaps came from the south as the temperature is now above freezing and are becoming sort of migratory birds too. perhaps escaped from their cages and learned how survive in the wilderness. grown in cages, most birds if get free often die as dont know how to find food and water. so it was a pleasant surprise i would say. it is 1 of the wonders of this spectacular land of the north, always full of surprises. (although some are not very welcome, like tornados and storms).
Posted by phil alvirez | Mar 06, 2016 @ 06:21 AM | 6,957 Views
once there was a boy sitting with his grampa at the porch when a dog happened to pass by. the other dogs at their homes barked at it when he passed by, but he didn't bark back, neither stopped to fight with them. just kept going...
them his grampa told him: that is a wise dog.
and the boy asked why?
he said: if he had stopped to bark back and fight, he wouldn't ever reach as far as he was intended for, or even reach anywhere.
never waste time barking at the other dogs. you will not be able to reach your goals. there will always be dogs barking at you, trying to stop you for an unproductive fight.
Posted by phil alvirez | Mar 01, 2016 @ 02:45 AM | 7,076 Views
recently when i went to my son, he showed me a new game to play with his daughter. it is called apples to apples. they post a card with a subject and give you 5 cards that have different subjects, and you have to make as many as possible to match as close or as different as you can with the 1 on the table. no matter how silly the excuse you have.
i couldn't play it. i found it as stupid as it could be.
i have spent my whole life doing what it takes to make sense to all that i do and think, to be logical, and with matters of science, to use data to reach conclusions. but i also realize that people play apples to apples everywhere. and sometimes even here at the forums, i find some that play that too, and am unable to communicate for that reason.
luckily there are few.
Posted by phil alvirez | Feb 13, 2016 @ 02:59 PM | 7,456 Views
my experience
i have been into sailplanes for many years (i enjoy catching thermals).
at the beginning, they were free flight (there was no radio control at the time). from 18" hand launch, to about 60" (1.5m) towline.
then, when radio control became practical and affordable, i got into that.
planes from 1.5 m to 2.5mt. then electric motor to assist climb.
the 1.5 seemed easier to handle and store, so worked with them for some time.
then went into 2 mt. 1st with 2 pieces wing. then 1 piece.
eventually i settled to 2 mt. and 1 piece wing-no ailerons, flaps, spoilers-nothing. just clean simple 3 channels. learned that don't need ailerons for thermaling.
learned that larger required 2 pieces wing, and made things more complicated than i needed-and couldn't see any improvement in flight, and also thermaling required larger size thermals.
am beginning to understand why the 2 mt is the most popular.
but that of course depends on each 1.
Posted by phil alvirez | Jan 27, 2016 @ 03:10 AM | 7,834 Views
i want to talk about another source for lift, that i have learned recently. it is a narrow band across the wind.
more specifically:
corridor: a stationary invisible narrow band across the wind, that generates lift.
this happens to me at a flat field with no elevations in sight (the only obstacle is a row of trees), located at 5km from a large lake. there is no wind blowing at the band mentioned; it is clear air all around; the invisible band does not drift (stationary for a long time). i know is there because the vario sends beeps that let me pinpoint its location; the wind does not penetrate it, and the band generates lift; i know this because i can keep my plane at that level forever. i have to keep the plane doing s turns within it to stay on the lift. if i turn the plane across it (facing the wind that is found below and above) the plane flies away of the band and sinks. the area is a narrow band across the wind (but wide enough to let my 2 meters sailplanes do full turns) that blows down here, and is present only at certain level (some 200 meters). ahead, behind, and below it, there is wind and the plane sinks no matter which way i turn, but drifts with the wind. and above, there is wind and sometimes i catch a thermal and drift with the wind.
i have been using 'wave' as it runs across the wind, to diferentiate it from 'streets', that run along the wind, but maybe this makes things confusing, as waves are generated near elevations.
at the end of the day, maybe '...Continue Reading
Posted by phil alvirez | Jan 20, 2016 @ 04:45 PM | 13,262 Views
when i studied aeronautical engineering in the 60's, i took meteorology. 1 of the things we had to learn was how to make a report of the direction of wind at several levels, with the purpose to tell pilots what direction of wind at different heights they could encounter. it is critical, as when climbing you may meet wind from the north and suddenly it changes to the south. it may be particularly critical for light planes. wind may flow at different direction depending of the level, and runs in layers, like blankets. if you have light models you may experience these sudden changes in direction. anyway, in those days we had to go to a small isolated room at the airport and inflate a large red balloon with hydrogen, as helium was not available. we connected it to the tank with a valve and let it blow to the point when the amount of gas made the balloon become buoyant while supporting the weight of the valve. this gave it the buoyancy to climb at certain rate. then we prepared a transit theodolite, pressed a switch that started a timer and released the balloon and aimed at it and pressed a button every minute. this punched a hole in a paper disc and as the timer activated a spring, each hole was punctured further from the center. it ended up as sort of a spiral, if the wind changed a lot. this way the experts could decypher it and make the chart of superior winds. the thing was that we had to do this in an isolated room because hydrogen is explosive, and we had to be extremely careful doing this as it could explode in any moment. some times the balloon just blew, and was a shocking experience because at that moment you felt that you were going to die in flames. to make things worse, there were moskitos around, and the silly beasts took the red balloon as something that they would like to pierce and then it blew.
a horrifying experience i would say. thankfully now with satellites and computers all over this routine belongs to the past.but it was something that you will never forget.
Posted by phil alvirez | Jan 18, 2016 @ 04:23 PM | 7,932 Views
once my plane disappeared in sudden dense fog and lost it. i never expected something like that. i never saw anything like that, or heard about it. there is a post somewhere down in this blog (page 4, Aug 03, 2013 ) where i mentioned it in detail.
it was not until now i found an article that mentions the situation. it says:
Coastal fog and low cloud can come in very suddenly. Cliff soaring can be full of hazards! I was amazed recently when on the east coast to watch a bank of sea fog reduce the visibility from 10 kilometres to around 100 metres in less than a minute (although this was not in fact a sea breeze effect)

this is taken from here:

as i was flying inland, also found this in the same article:

A strong sea breeze front could move up to 50 kilometres inland
so now i understand what happened to me, although it is a rare event.
Posted by phil alvirez | Jan 14, 2016 @ 08:54 AM | 6,715 Views
1 of the most valuable things i have learned, now that am dealing with electronics and having to program everything, from the answering machine to the range, and of course our radios, is that, if when programming something it does not work, is trying again.
don't know why, but it works many times.
don't get scared, just try again.
maybe won't everytime, but it's worth trying it.
Posted by phil alvirez | Jan 11, 2016 @ 12:41 PM | 6,002 Views
conclusions (revised)
based on the opinions from very knowledgeable people, am compiling the data about charging lipo cells in parallel.
this is what i have learned from all the comments from experts:
regarding the installation:
use cells spot-welded (or with tabs and then soldered)
if soldered in parallel you can't check the condition of each cell;
if is series you can, but you have to add 1 extra wire coming from each cell (this is the common way we find in lipos).
with this extra wire each cell is also charged and balanced.
with cells installed in a battery box and connected with springs, there is the risk of having false contacts, but you can charge them individually and keep the pack balanced.
you use parallel connections when you need to keep single cell voltage for the pack, and series if you need to increase voltage to the sum of all.
when using nicads or nimh you can live without checking their condition, as they are tolerant to disbalance.
in the case of cells in parallel, as you can't check volts of each cell, i heard from dickw that you can get an idea of the pack condition by measuring the charge they take and keeping records, so you can see if the pack is going down and needs to be dismantled and you can check each cell and replace the one(s) gone bad.
for this you need to have a charger that measures the charge.
but could be that i did not get it right in something, so i would like to hear your comments about this
the reason for this quest was that i learned that the radio am using has the option to use lipos in the transmitter, and this works for some guys. see their comments;
Posted by phil alvirez | Dec 21, 2015 @ 02:24 PM | 7,112 Views
today i was sent this and tried it. how about you?
it could be good to improve your reactions when flying your plane.

Posted by phil alvirez | Dec 20, 2015 @ 01:05 PM | 7,268 Views
those were the days!
i was getting memories of my early days (about 5 years old) when we lived downtown in a 1 level apartments building that had gates so only the residents children could play around. there was a paved street, with sidewalks, and i rode around on my tricycle. there was a fountain with white and blue tiles and 4 frogs that were spitting water, and some gold fish too. the house had a patio layed with bricks and a trellis with a pink bougainvillea and at night there were trains of assorted colors (worms that glow at dark like fireflies) and sometimes fireflies too. there was another patio at the back where my mother washed the cloths and used the same tin tub, that she filled with water so the sun warmed it up for me to bath in the afternoon. i just got in and played with my rubber ducklin and she sung sons to me when she bathed me. 1 of them was about swallows, that came in spring and left in fall, and everytime i cried and the tears ran all over my face and body to the water. whenever i asked her to sing it she said that i cried and i said that i liked it anyway. memories that have enhanced my life...
Posted by phil alvirez | Dec 20, 2015 @ 12:26 PM | 7,186 Views
i started a thread on the modeling science forum about a new adhesive that could revolutionize assemblying and repairing models.
see it there and bring ideas and links if you can.