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Posted by phil alvirez | Dec 07, 2017 @ 01:05 PM | 1,086 Views
i read a report of a mystery problem found in a great airplane, that shows that even with planes that seemingly perform good, there are things that happen that go unexplained. pay special attention to the end of the article.
https://airfactsjournal.com/2012/11/...uring-mystery/
and things like this also happen with our models
Posted by phil alvirez | Dec 06, 2017 @ 11:45 AM | 1,568 Views
sometimes you loose radio signal, or becomes erratic. even results in a crash. checking the radio afterwards, all seems fine. and when this happens and some1 is around, or you talk to some1, frequently they say or think that is was pilot error. yes, sometimes a crash is due to that. but when the loss happens to you, with no1 around, and you did not make a mistake, you know it was not you.
then, what happens? perhaps something in the atmosphere? give a look at this report: http://cdn.intechopen.com/pdfs/16080...o_humidity.pdf and this: https://www.reddit.com/r/askscience/...r_atmospheric/
https://annals-csis.org/Volume_5/pliks/241.pdf
at the end says: In summary, our study has the following main contributions:
We show that changes in weather conditions affect radio
signal strength. Temperature seems to be the best explanatory
variable for signal strength variation and has a
negative, linear effect on signal strength in general, while
high relative humidity may have some effect, particularly
when temperature is below 0◦C.
We show that correlation between signal strength and the
studied weather variables vary depending on radio channel
and link. Applying frequency diversity will alleviate
these effects.
We show that smaller transmit power results in smaller
unexplained variation in received signal strength (in most
cases) and thus stronger correlation with the studied
weather variables
i used to fly...Continue Reading
Posted by phil alvirez | Dec 02, 2017 @ 08:17 AM | 1,908 Views
i always have been fascinated with soaring. staying up without motor. like the birds!
at the beginning, and for many years, i flew free flight, as there was nothing else available. and learned about thermals. with hand launched gliders, then towline gliders, rubber powered planes. engine powered planes.
many years later, when radio became affordable, i got into thermal at will. that is, when i learned to find them.
now with vario is easier, as it tells me the height or if the plane is climbing or sinking. but always a pleasure to me.
recently began to experience some situations where i could make my plane stay longer without a thermal, and explored the slope and dynamic soaring. i found data at a forum, that was enlightening: https://www.rcgroups.com/forums/show...ynamic-soaring
still, what i found by chance does not match what these guys say. what happened was that once i found my plane flying a little bit faster than the wind and decided to do lazy 8s facing it so it didnt go beyond the area where i wanted it to be, and noticed that it didnt sink for a few seconds (i have a vario that tells me the height every few seconds) and became intrigued. i have reached the conclusion that it is sort of dynamic/slope effect. except that this happens in midair-no hills/cliff.
the way i see it is this: when my plane is flying at a speed slighty higher than the wind, i do lazy 8s facing it. that is: fly across the wind, then turn facing it. when the plane raises...Continue Reading
Posted by phil alvirez | Nov 16, 2017 @ 04:59 AM | 1,974 Views
learned about these cells for umx planes similar to the radian:
https://micro-motor-warehouse.com/co...eid=4db1759bcc
eventually finished performing tests on these batteries. just in time for fall to arrive with winds and rain
i used the hobby king nano cells for comparison https://hobbyking.com/en_us/turnigy-...kzone-etc.html
1st did bench tests using a umxradian and running the motor at half throttle (stick vertical) while holding the plane on my hand, and stopping every 30 seconds and taking readings of the voltage remaining.
umx radian: https://www.rcgroups.com/forums/show...0mm-Version%29
i used the hobby king cell 160 mah as a point of comparison:
https://hobbyking.com/en_us/turnigy-...kzone-etc.html
and the 1st 1 from micro motor is this: https://micro-motor-warehouse.com/co.../mylipo-150mah
the way i did the bench tests was installing the cell in the umx radian and run the motor at half throttle (stick vertical) for 30 seconds, stop and measure volts. then again. until reached the minimum recommended.
time and volts
seconds--------30------60------90-----120------150-------180-------210-----240------270------300-------330------360-----390------420---450---480
1: hk 160-----405----395----389-----384------380-------377-------374-----371------368------365-------359------345
2-150/25c----408----396----391-----385------381-------378-------375------373------369-----365-------353------312
3-150/45c----409----399----393-----388------383-------379-------...Continue Reading
Posted by phil alvirez | Nov 05, 2017 @ 10:38 AM | 1,752 Views
there is a point in life-and in modeling-that, as Kenny Rogers in the song, you need to know when to run.
once you have reached certain goal, or when you are satisfied with what you have or do, why try something else?
or when you no longer can do something, or dont enjoy doing it anymore

Kenny Rogers - The Gambler (2 min 54 sec)


https://www.azlyrics.com/lyrics/kenn...hegambler.html

i have reached a point where i cant find anything else to learn about modeling, or have anything to do but fly my planes.
and that is a great thing because, after all, the main goal of this hobby is flying-or whatever specialty you do-and enjoy your model.
so, life is good anyway.
Posted by phil alvirez | Nov 03, 2017 @ 09:01 PM | 1,987 Views
with early winter hitting, i am getting back to my den and paint (my other passion), instead of model airplanes, so will not hear much from me. and when spring is back (who knows when) will fly again, but still not much to talk or explore new things, as i already have everything i need for a long time, and too many planes ready to fly, so dont have an excuse to build another
so long folks
and thanks to all that have been so helpful
Posted by phil alvirez | Nov 01, 2017 @ 02:25 PM | 2,884 Views
we all are so accustomed to transistors, and could not live without them, but, what on earth are they?
there is an article at wiki: https://en.wikipedia.org/wiki/Transistor
but on it they say that: 'The term transistor was coined by John R. Pierce as a contraction of the term transresistance. '
on the other hand, national geographic provides another explanation that, to me, is more believable.
it was explained in the "100 scientific discoveries" issue/page 27: "This technology transfers current across a material that normally has high resistance (in other words, a resistor); hence, it is a transfer resistor, shortened to transistor."
Posted by phil alvirez | Oct 20, 2017 @ 04:21 PM | 3,281 Views
i have talked about this issue several times. i watch fellows that do great while in the air: all kind of stunts and whatever happily. but when landing...is another story. there is a fellow at the club that comes with a big aerobatic plane and does whatever he wants. all kinds of stunts. am flying my gliders up there so i cant follow what he does, so i dont see how he makes the approach and what he does wrong, but every time he approaches mother earth its a disaster. he returns with the plane minus landing gear. with my gliders i try to land smooth and as close as possible, but i have reached a conclusion that it is better to have a good landing far away, than a nearby crash. and again, that flare-off idea of landing sometimes is not the most convenient. approaching with some speed and a little down elevator and sweep the ground instead so there is no floating and stalling works better. just consider it.
and above all, practice. if you fear it, perseverance is the key. you reach a time when it becomes natural. is like anything: you are learning. so, learn.
Posted by phil alvirez | Oct 18, 2017 @ 05:43 PM | 2,879 Views
soaring
am starting a discussion about soaring. please bring your experience on the issue or comments or follow-up.
according with dictionaries, soaring can be considered as climbing or staying up.
see:
soar
sr/Submit
verb
gerund or present participle: soaring
1-fly or rise high in the air.
"the bird spread its wings and soared into the air"
synonyms: fly, wing, ascend, climb, rise;
or:
2-maintain height in the air without flapping wings or using engine power.
"the gulls soared on the summery winds"
synonyms: glide, plane, float, drift, wheel, hover
"the gulls soared on the winds"

https://www.google.ca/search?hl=en&s....0.s3D66D2_p9Y
keep reading the comments below.
Posted by phil alvirez | Oct 06, 2017 @ 08:59 AM | 3,065 Views
have you wondered how bolts/screws/nuts are made?
i found this documentary very enlightening. i hope you will too:
How It's Made Nuts and bolts (4 min 29 sec)

Posted by phil alvirez | Oct 05, 2017 @ 12:16 PM | 3,105 Views
i have to tell you this: today at 8:00 in the morning, with clear sky, no wind down near the ground or up, launched my 2 meters electric power glider to 200 meters, stopped the motor and began to turn around searching for thermals. suddenly noticed a large number of small birds swarming above my plane. they were very high too, as far as i could see. flying fast in all directions, but always above my plane. if i flew it into another direction, there they went. it was not until my plane went below 60 meters that they dissappeared as fast as they appeared. every flight. i can not imagine how they came so fast on a sky that didnt show any few moments before.
perhaps they thought that i was into a thermal and decided to take a free ride? i can not think of anything else
i hope some have been in an experience like this, or has witnessed it, and could bring an explanation
here is a link on other's experiences but none like me: https://www.rcgroups.com/forums/show...ds-Birds-Birds
as far as i have been told, they are swifts. here is more data from wiki: https://www.google.ca/search?hl=en&e....0.vqSfsVZFfCA
Posted by phil alvirez | Oct 03, 2017 @ 11:02 AM | 4,200 Views
i am into thermaling. 2 meters electric powered. and i wonder why some birds-that are very good at thermaling-have short wide wings, and others, that are not thermal birds, have long narrow. examples of short are buzzards, eagles, haws, and long are albatross. perhaps because the short fly on the ground, and albatross over sea?
a link to short: https://www.google.ca/search?q=shape...w=1266&bih=558
and here albatross: https://www.google.ca/search?q=shape...w=1266&bih=556

seems that, after all, it is the way each flies. 1 using dynamic soaring, the other thermals.
read the comments; especially the latest.
Posted by phil alvirez | Oct 01, 2017 @ 11:47 PM | 3,185 Views
am starting this subject here at my blog.
i was running it on the open but got too many negative or non related posts so this way i can keep this clean.
it was here: https://www.rcgroups.com/forums/show...ing-efficiency
so, welcome all who want to follow up that thread
i said this at the beginning:
am starting a forum with the purpose of discussing the design to reduce the planes sinking speed.
the idea is that with the minimum sinking speed the plane may stay longer-and perhaps catch thermals easier.
please, only bring your experience or ideas related to the subject.
sinking speed
am bringing this from another thread, where we were discussing another subject:
"at the present time am performing tests to find out which is the optimum wing loading to stay up as long as possible for thermaling.
and building too light could make an airplane to sink faster after all. i have several 2 meters e-gliders, and the lightest flies noticeably slower, but that, even if very impressive, not necessarily means lower sinking speed. could be that it just does not penetrate enough.
the only thing that occurs to me is, besides timing them from same height in still air, is checking sinking speed and forward speed too. "
>>>after testing, i learned that the lighter, slower, sink faster, so after all, there is a limit that, if you go beyond certain weight, the plane just does not penetrate. period. but this can only be learned if you check the time from...Continue Reading
Posted by phil alvirez | Sep 30, 2017 @ 11:46 AM | 3,190 Views
past sunday was my 83rd and the happiest! at my son's, with his wife and 10 years old daughter, who baked a cake and muffins, and decorated all with all kinds of stuff. pictures, everything. couldnt be better. and she also gave me a balloon, a card hand made and decorated, and an album with pics of all of us. i was in heaven. and forgot to tell that early went flying and all went fine. even the weather.
Posted by phil alvirez | Sep 21, 2017 @ 04:41 PM | 3,063 Views
it all started when i began to loose signal or facing erratic response. at the time i was flying early in the morning at a field near radio towers. tried changing everything, and was adviced to try another field. there the problems were gone. but they didnt allow to fly until 10 am.
then i realized that i was having false contacts at the individual cells of the radio, so replaced with welded packs. so i decided to try at the 1st field, and for some time all went well. and suddenly the problems began again. now i was facing fog for several days, so that made me think that it could be the reason. checked at the net and some confirmed that radios are sensitive to high humidity. and as at the other field i was not allowed to fly until 10, by then there was way less humidity. so it was why there i couldnt face the humidity-and the problems. i must add that, as i use a vario that runs independently from the radio, i have noticed that sometimes it stops sending signals, which means it is not reaching the receiver at my neck. a confirmation that humidity blocks the signals.
so now i know that:
1-radios that use single cells connected by pressure are prone to false contacts.
2-high humidity blocks signals.

i hope this experience will make your life easier. just remember if this happens to you. or try to avoid this.
regards
Posted by phil alvirez | Sep 11, 2017 @ 07:32 PM | 3,519 Views
today i found myself in a new situation. and never heard of it. i was flying an electric glider early (around 7) on a clear sky, and there was a moderate breeze from the east at ground level. i climbed to about 150 meters, stopped the motor and turned into the wind. it was moving slowly forward and began to sink. then reached another layer and began to move backwards until reached a lower layer, where began to move forward again. the wind was blowing from the same direction. for all that i have learned and witnessed, wind increases as is further from the ground in what is called a gradient, but here the wind was blowing faster between 2 layers. i have been into layers where the wind blows from several directions, but always the higher the faster.
and when i thought that i had seen all!
Posted by phil alvirez | Sep 03, 2017 @ 03:38 PM | 3,562 Views
just as a storm has a place where winds change to still-and then go back on full strenght, i have noticed that winds sometimes slow down for a while and then return. sometimes this happens when winds change direction. as i fly early in the morning, i am always looking for this to happen, even in windy season. it may be for only 1 hour, or even 2, but that is enough for me to test or just enjoy a quick flight or 2.
i watch at the channels of the weather, and take a chance. most of the time it works. even if not, it always helps me by getting ready and checking everything and enjoying the trip to and back.
Posted by phil alvirez | Sep 01, 2017 @ 04:53 PM | 3,920 Views
now, when we thought we still had 1 more month before winds and storms were going to arrive, it feels like fall came 1 month earlier. just look at the forecast: at least 1 week with unbearable winds-and then who knows when-or if-we will have the chance to do more flying.

at least we had some good weather-even if spring arrived over 1 month late


after all, if this is the worst thing we have to face, just think of the guys at the gulf
Posted by phil alvirez | Aug 15, 2017 @ 02:01 PM | 4,937 Views
when i took meteorology i did reports of wind direction at several heights. i learned that wind moves horizontally in layers, that sometimes move in different directions, and therefore you may find your plane changing direction due to this. it is particularly more noticeable when flying gliders, that are trimmed for detecting subtle changes in the wind, be horizontal, or vertical. i have witnessed this frequently, and yesterday it was even more clear.
the wind at ground level was easterly, but when climbed to 100 meters (320 ft) the plane changed direction by wind blowing from the south. and i could see the clouds above moving from the west. my plane was no that high, but when came down to the 100 meters level, it fell into the ground level layer from the east and changed direction again.
it is what those who fly balloons use to change direction by climbing or descending depending of the direction of the wind in those layers.
fascinating matters of the air....
Posted by phil alvirez | Aug 14, 2017 @ 10:31 AM | 5,012 Views
i have read about measuring sinking speed, but have not seen figures that can be measured sistematically so we can have some certainty.
perhaps some1 has a method and can bring data or links.
in the meantime, as i design and fly gliders and have a vario installed that tells me the height at glide every 20 feet, it occured to me to time when reaches the next figure. i tried this with 1 of my planes.
now was a matter of dividing feet by time. took several times and got an average of about 14 seconds, so this tells me that the average sinking speed of that particular plane is 1.43 ft/seconds. will keep doing this with all my planes. with this i will learn which 1 is more efficient by staying longer in the air. this way i can reach conclusions on whatever i change on my planes.
>>>sept 15: update: i finished taking readings, and also noticed that in some of my planes, even if fly slower, the sinking speed is higher, so i began to measure flying speed too with another instrument (named "how fast"-no longer available). and if climbed to certain height (100 meters, for instance) and then started timing the flight, i got all that i needed to learn which plane takes more to land. it is 1 of those things that even if easy, are tedious work, but eventually i got all. i started a forum trying to learn if some1 has done something like this, or an even better way, but so far nothing has shown.
so from now on, when i change something in my planes, i have the way to see if it was an improvement-or not. real data.