phil alvirez's blog View Details

modulation-what on earth is it?

Posted by phil alvirez | Yesterday @ 08:42 AM | 9,169 Views
i think you have heard this word before.
in simple words?
Modulation is the act or process of giving a wave or signal the amplitude or frequency of another wave or signal. In telecommunications, modulation is the process of conveying a message signal, for example a digital bit stream or an analog audio signal, inside another signal that can be physically transmitted.
and, how it works?

or in wiki terms: https://en.wikipedia.org/wiki/Modula...%20transmitted.

i hope you will see things more clearly... or less muddy.

tracks on a micro brick-part 3

Posted by phil alvirez | Jan 12, 2022 @ 08:22 AM | 30,463 Views
see part 2 here: https://www.rcgroups.com/forums/show...-micros-part-2
trying to understand what the 2 strips in the linear servos tracks do, i got these answers from John:
" As the servo carriage moves up and down the amount of red resistor in the circuit between A and B varies linearly from zero to 5K. ".
if i were pushing a pot, the mechanical action changes the amount of current, but here is the opposite:
i send the signal, and then it somehow makes the carriage move in the direction needed.
i know that the motor turns 1 way or the other and this pushes the carriage, but how the motor gets the signal for that and decides the amount? answer:
the servo circuit has a part that creates a square wave pulse. It is essentially a square wave signal generator. The width of the pulse is set by the resistance of the red bit which is an input to the generator. At the same time the incoming transmitter signal creates a square wave pulse. Both of these pulses can vary from 1000us to 2000uS.
A comparator circuit in the servo chip compares the two pulse widths. If they are the same nothing happens. If they are different the difference or “error” signal drives the motor in the correct direction to make them the same. When they are the same the motor stops.

DX6G3-understanding the manual

Posted by phil alvirez | Jan 10, 2022 @ 04:46 PM | 25,761 Views
https://www.horizonhobby.com/on/dema...-Manual_EN.pdf
am starting this with the purpose of being able to use this radio for my goals, and thinking that are others in the same situation.
there are some things that are not clear to me so am making comments about it.
am getting directly into the System Setup, page 14:
the 1st thing we need to know is how to turn it ON:
1-to enter, press /hold the roller
2-turn the switch ON
3-release the roller.
now you are in. you see the screen illuminated.
it shows the 1st of 2 pages. if you want to search for more functions just keep pressing and the rest will appear.
for this, in system setup, you dont need the receiver to be connected.
next is:
Model Select
1-roll to the desired model memory in the list
2-press roller. you are back to the system setup list.
here the manual talks about adding a model , but this to me is the same as "create a new model" in page 17.
next is Model Type
just choose which is this model and press roller
Model Name
this is as shown. no changes.
next shows the 3 types.
but if you have a sailplane with motor you cant choose sailplane.
you have to choose airplane, so all the alternatives at the table for sailplane cant be used.
(i will skip page 16 and trim setup for now)

tracks on a micro brick-innards of micros-part 2

Posted by phil alvirez | Jan 09, 2022 @ 01:52 PM | 30,141 Views
when i opened a brick to check the tracks for condition i found 2 tracks per servo.
not knowing how the 2 tracks work, asked an expert and he told me:
The brass coloured track in your picture (blue in the diagram) is a conductive strip with essentially zero resistance. The black one (red in the diagram) is a carbon resistor often 5k Ohm total resistance from one end to the other.
The little metal slider connects the two tracks. I have called it a wire slider as some servos have that but in the case of the Spektrum bricks it is a set of multiple springy fingers.
As the servo carriage moves up and down the amount of red resistor in the circuit between A and B varies linearly from zero to 5K.
The 5k figure might not be correct as I have not measured the track resistance. It may be 10k or some other value but 5k and 10k are common values in RC servo pots.
John (JJ604)
you can see the drawing here:
and the pic of the module at the part 1 below in my blog.
https://www.rcgroups.com/forums/show...of-micro-brick
this has been confirmed at part 1 by other experts too.

Posted by phil alvirez | Jan 08, 2022 @ 09:42 AM | 25,724 Views
part 1
so far there are 3 versions:
1-the original
(i will call it V1);
2-the AS3X: (Artificial Stabilization 3-Axis System).
(i will call it V2)
the official description:
Programmed through a Spektrum receiver you will find an 'Artificial' Stabilization 3-axis system or AS3X. This is specifically programmed for the airframe it is installed in and will help keep the aircraft level in flight in even the windiest of conditions;
3- the same as 2 and with telemetry. meaning that we get the charge of the battery in volts. this reduces the risk of running out of power.
but you need a radio compatible with telemetry too.
(i will call it V3)
this new has the part number EFLU2950. when ordering, make sure you specify this and when the parcel arrives, check the box shows it.
also, if purchasing at a store verify it. otherwise you may get the older version without telemetry.
but it does not include the battery and charger. the previous 2 did.
also, posted this recently on how the brick looks, in case you need to open it for repairs or clean-up: https://www.rcgroups.com/forums/show...of-micro-brick
when i learned of the 1st 1 i got it and began to fly it at a park nearby, as often as the weather allowed. lots. until began to fly erratic.
when the 2nd was released i got it too, and as it allowed me to fly even often due to the stabilizer, i got another 1 as a spare-that havent flown very much. the stab really let me fly under conditions that otherwise wouldnt....Continue Reading

innards of micro brick-part 1

Posted by phil alvirez | Dec 20, 2021 @ 10:56 AM | 13,332 Views
part 1
any1 interested in seeing how a brick of a micro model looks from inside? (i havent seen this anywhere)
if you own 1, or just curious, here it is.
i opened it because the radian, where it was installed, began to behave erratic. this is the 2nd version with the flight stabilizer which, by the way, performed great. the micro plane could be flown in turbulent air that otherwise is too much for this size.
but nothing comes from nothing. the price that has to be paid is that the contacts that touch the tracks are vibrating non stop and therefore wear out the tracks at the same speed. and, as if flew this 1 a lot, eventually this is what happened.
what puzzles me is that there are 2 tracks for each servo, 1 of which looks worn out, but the other seems intact.
if some1 has an answer, or an idea, is welcome.
and, as i said, even if there is no way, now you know what is inside, folks.
in the meantime will keep trying to find a way, so keep posted....
update: as i have several bricks (and planes with them), i opened them to compare and learned that on some, the yellow track is way cleaner due perhaps to less use, so decided to clean the 1 in the picture even more with the eraser (thanks to RickC for the advice). soon will be able to test it and see if this fixed the problem of erratic response.
bench tested both and, after the cleaning, seem to respond well. but the definitive answer will be only when am able to fly them. and that will take at least 3 months,...Continue Reading

attacked by hawks?

Posted by phil alvirez | Oct 19, 2021 @ 12:40 PM | 15,060 Views
who can provide data on being chased by a hawk or whatever?
i ask because i got chased by a hawk.
i was flying my 2 meters electric glider midmorning. when climbing i noticed a bird following my plane but quit when i was near 200 meters.
then i got into a thermal for a while but when lost it and reached 100 meters here the bird came back, this time to remain following my plane and attacking it, sometimes getting very close. i changed direction but here it came until landed. the bird landed at a place so next flight i avoided that area and it did not chase my plane again.
could be that it was nesting?
any1 with experience with something similar is welcome.
here are some videos showing attacks: https://www.google.ca/search?q=model...client=gws-wiz
speaking of hawks, once i made 2 planes that look like birds. 1 left it white (looks like a gull), and the other painted like a hawk. i quit flying it because as soon as i launched it, all birds disappeared. https://static.rcgroups.net/forums/a...2-IMG_3785.jpg

induction motors: the future of our models?

Posted by phil alvirez | Oct 18, 2021 @ 06:57 AM | 19,903 Views
found this article on the differences interesting. i hope you find it too:
http://www.omagdigital.com/publicati...wser&ver=html5
well, from this thread i got some comments at the end that seems as it is not so good after all. look
https://www.rcgroups.com/forums/show...model-aircraft

thermals or what?

Posted by phil alvirez | Oct 10, 2021 @ 07:46 AM | 31,579 Views
october 9, midmorning, about 20c (70f), 8 kph (5 mi) south wind, flat farmers land all over; 2 meters sailplane. climb to 200 meters (640 ft). vario tells climbing. so i turn and drift with wind until getting too far so turn back south. but then, flying on, straight facing the wind, plane remains at same level, or slight climb.
once back overhead, turn again, follow a cloud and catch another thermal, drifting with the wind and remain on it turning. over and over. later, noticed that flying straight facing the wind or drifting with it, the plane climbs slightly. tried other areas but cant find these conditions. is like a tunnel that runs along the wind where air is going up. this last over 40 minutes. then drifted over other areas. there was some buoyancy and the plane just didnt loose altitude.
when making the approach for landing, took some 10 minutes to land. sky most clear, few low level puffy clouds.
this is the 2nd ultrawhatever experience with non normal thermal conditions where the plane climbs even when not turning.
i hope some1 could bring experience with weird climbing air conditions.
here is the other experience:
Posted by phil alvirez | Jan 27, 2016
soaring: waves and stranger things: corridors
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 happened to me at a flat field...Continue Reading

why flying electrics?

Posted by phil alvirez | Oct 01, 2021 @ 03:34 PM | 12,534 Views
it is a fact: they are here to stay.
what i would like to mention first is that you can run out of power and then the craft drops like a rock. if you are flying power (not gliders) you may notice a loss of power, but that may not give you time to return and land. and with gliders, that dont use the motor except for climbing, there is no way to know it.
if you fly with radios that dont have telemetry, you are at loss. and if your radio has it, then you have to learn how to program them. and that sometimes is burdensome.
then you have to know how to deal with the batteries, chargers, adaptors, connectors...
i have seen fellows that bring a car battery to recharge their batteries at the field!
and then, what size for your plane (capacity, dimensions and weight). what options. where to find them and at what prices (and shipping). at what rate to charge those.
and, as electrics start by just flipping a switch, they are dangerous. you HAVE to add another switch, or learn how to use 1 already in the transmitter, that you dont need or can substitute or live without that function. this way you have to activate it just before launching/taking off.
there is much more to add.
but these are the basic things to consider.
of course, internal combustion (engines) provide more power per weight, but with the increase in limitations due to noise pollution, sometimes there is no other way but electrics.
also, some like the easiness to fly them, as there are no possible problems: just flip the switch and the motor starts.
and for gliders, where you can start the motor any time, as when you drift too far and otherwise you will not be able to return to the field, or when you may fall short when landing, this is something you wouldnt even dream of.
for scale models, there are no engines protruding.

lithium batteries: whats up ?

Posted by phil alvirez | Sep 18, 2021 @ 02:58 PM | 12,085 Views
perhaps some data on our source wouldnt hurt.
how were invented and developed is a fascinating story. enjoy.
https://en.wikipedia.org/wiki/Lithium-ion_battery

flying r/c models...

Posted by phil alvirez | Jul 11, 2021 @ 10:02 AM | 5,607 Views
getting started presents several situations that are worth commenting in detail:
1-what to do;
2-how much movement;
3-how fast;
4-orientation;
5-getting drowsy;
6-getting tired;
7-not getting the feeling;
8-practice.

1-what to do. how do you know what to do to make the plane do whatever you need:
a transmitter has 2 joysticks. the most common way is: left stick: throttle and rudder. push forward means motor runs faster; push left: model turns left.
right stick: forward means dive; left means left wing sinks. now you know what to expect. great!
2-but then you dont know how much movement-that is, until you are flying the model. and most of the time you overthrow. but there is an alternative: simulators!
getting 1 allows you to familiarize with both things: with practice you dont have to think what stick move which way, and also the amount of throw tells you something. and when practicing, if you do something wrong you dont crash the model. this lets you learn way faster and saves you the frustration.
3-also you get some idea of how fast react to any situation. moving slower than needed in some cases the plane does not recover in time; moving too fast in others the plane becomes too flimsy. takes time to learn this too.
4-flying a plane when it is flying away from you is easy: if you want to turn left you just move the stick to the left and the plane follow your command. but when it is moving towards you, you have to move the stick the opposite way. this...Continue Reading

Reynolds numbers for models

Posted by phil alvirez | Jun 23, 2021 @ 10:22 PM | 20,641 Views
this is dedicated to those who are interested in improving their knowledge on aerodynamics. it is a science that has been applied also to model airplanes.
but is has been discovered that there are some laws that dont apply so well. and took some time and research to learn that indeed, there are laws that are specific for models.
and this is easier to understand by following the next:

Reynolds Number (Re)-A simplified approach.

There is a difference in performance of a wing, depending mainly of its size (chord) and speed, and Osborne Reynolds managed to put that together in an equation that lets us predict its behavior.
In charts that show the lift and drag, the curve changes depending of the Re. The stall, the max lift and drag happen at different angles of attack, and the efficiency changes, too.
There are several ways to determine the Reynolds number. A simplified way is if we multiply the wing chord (in feet) by the speed of the plane (in ft/sec), and then divide it by 0.000157
If we know the speed at which certain airplane is flying (and its chord), we can calculate its Re with this equation (and that speed can be measured with a device called ‘How Fast’). seems that still is available here (and the see how too): http://nemhobby.com/how-fast-p32614.html
Now we are ready for this:

Making sense of it all.

I am presenting this to be analyzed by everybody, and then each one to decide if it makes sense to him.
From the beginning of the 20th...Continue Reading

swifts

Posted by phil alvirez | Jun 08, 2021 @ 06:33 PM | 20,989 Views
i fly 2 meters sailplanes. climb with an electric motor to 200 meters in 30 seconds, stop the motor, the propeller folds and i search for thermals to soar.
i spend as much time as the weather conditions allow. 1 day with clear sky (no birds in sight) i went flying and , after the motor stopped i began to search for updrafts. but suddenly, about 50 meters above my plane, i noticed a huge swarm of tiny birds flying fast in all directions. looked as if they were going nuts! as i drifted searching for thermals, i noticed that they moved above my plane. then i turned back to where i was, and they followed my plane. tried every maneuver i could think of, but i realized that they were following me. it was not a coincidence ! as i couldnt find thermals, my plane began to loose height, but they followed me on the descent, until when i was about 60 meters high, they suddenly disappeared. i couldnt believe my eyes again ! how could they show up and vanish so fast? where were they before and after? i did 3 more flights and same story. as i recalled, they looked like swallows, but that was all that i could learn. took me some time searching to learn that they were swifts. what could they see in my plane to remain above it? and not so close, just above...
and this never happened again.
wonders of the sky, that even when you think you knew all, it has something to amaze you!

the key to happiness?

Posted by phil alvirez | May 19, 2021 @ 01:50 PM | 39,806 Views
once i lived in a house that had a large trellis that covered the whole sides including windows. to trim it to clear the windows i had to chase a fellow gardener that had a tall ladder, but couldnt find him before 11:00 am. when i asked him why i couldnt find him before that time he said that he didnt need to work before to get all the money he needed. at the time i found this silly, but after many years chasing more money, i failed to realize that what matters is to understand what you really need to be happy.
now that am retired and live a quiet comfortable life i see the wisdom of that modest fellow that was aware of what he needed to be happy and didnt push beyond that. to me, learning this is the key to happiness.

in perspective...

Posted by phil alvirez | Mar 30, 2021 @ 10:22 AM | 12,811 Views
there is a time when suddenly you see the light. and the way is to see things from afar.
and to me is now. i have been into model airplanes since i was 5, and even with interruptions for building or even just flying, they have been in my heart all the time. my fascination was to catch a thermal (those days there was only free flight), and still is now. i fly sailplanes with remote control (r/c).
even if things have changed beyond the wildest dream. now we have this electronics technology everywhere. and this adds another factor that i wouldnt even think about before: that now i can detect thermals and chase them! so, whenever the weather allows, am at the field, having the time of my life!
but i got carried away with this fascinating technology. so many radios, batteries, motors, electronic speed controllers, batteries, whatever, so much to learn, to try, it has become and endless race to catch up, and that has brought us into a whirlwind that does not allow us to see what really is going on.
recently i have been struggling with some parts that are not behaving as expected, when i realized that, well, perhaps i really dont need them. that simple!
so am going back to basics. what i really need to hunt thermals?
and this also applies to whatever specialty you guys are into: what are you guys aiming at? are you enjoying it? that is what really matters!
are you going too far? thats up to you to decide. but this is just a wakeup call, thats all.
think about it... and enjoy this wonderful hobby the best possible way. cheers!
 Bird’s Secret To Soaring Super High (3 min 9 sec)

self-charging batteries ?

Posted by phil alvirez | Feb 03, 2021 @ 10:16 AM | 18,070 Views

batteries update

Posted by phil alvirez | Nov 01, 2020 @ 03:14 PM | 19,519 Views
just in case you havent heard of the latest, here are some of the possibilities for better batteries:

enjoy

origins of r/c

Posted by phil alvirez | Oct 16, 2020 @ 09:32 AM | 15,987 Views
 Good Brothers Pioneers in Radio Controlled Model Aviation (25 min 50 sec)

then was then...remote control (part 4)

Posted by phil alvirez | May 28, 2020 @ 11:46 AM | 18,993 Views
see parts 1-3 at my blog
from time to time, model airplane magazines published articles on sort of science fiction by mad scientists that were performing experiments with remote controlled airplanes.
these were as rudimentary as they could be. free flight planes controlling just the rudder, and that happened erratically. it was sort of lottery to be able to change the direction of the plane now and then.
but, as i said, it was just trying the boundaries of the then fantasy of controlling something at a distance.
this took years and the contribution of countless (and nameless) folks to reach the point of being able to control also elevator, then throttle.
the gear consisted on a car battery placed on the ground that provided the power, connected to a control box that the modeler held in his hands.
those who were present were in awe, and talked about this for a long time to whoever were around.
then came reeds, that improved efficiency. there was 1 channel for left turn, and another for right turn.
when elevator was added, same thing: 1 channel for up, another for down.
then servos. nicads. years later, some1 released the 1st commercial radio control (kraft, i think). and expensive. heavy.
and they were flying on frequencies (72, 27), so you would not have interference.
i recall at los angeles, there was at a place called mile square, that was an emergency airstrip (dont know of still exists), that had large areas designated for each frequency where the ones that were willing to fly formed and awaited for their turn to fly.
it was until, on 2006 that horizon released the 2.4 with which apparently any number of planes could fly without interference.
now we also have cellulars, laptops, gps and whatnot.
boy, the world has come a long way...