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Mar 07, 2009, 12:13 PM
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My goal is to have fun.


17 mar 2018
thinking is a privilege that God graciously gives us to enjoy.
sadly, only a few make use of it.

22 feb 2017
the learning curve: there are no failures: when something does not work, you learn that. it is not that you failed. it is 1 thing that does not work. thats all. you are learning! now that you learned it doesnt, try again in a different way. until it works. in other words: life is a series of attemps to get something. until you do.

17 jan 2017
Luck is a Lady who smiles only upon those few who know how to make her smile
-Hans Seile-

26 aug 2016
life is not a 100 meters race: it is a marathon!

26 aug 2016
winner is not that who wins a game or a race.
winner is that who never gets discouraged.

23 feb 2016
life is 1 of the things that wear out-even if you don't use it

22 jan 2016
through all my life, i always have been amazed of the tremendous effort humans put trying to make my life miserable.
and how miserably they have failed!

11 jan 2016
tomorrow begins today

2 dec 2015
we will be disapointed if we fail;
but we will be doomed if we don't try.

8 nov 2015
we will never be able to reach the right conclusion if we judge by exceptions

10 sep 2015
giants have their heads in the clouds
and their feet on the ground

10 sep 2015
just a thought:
thanks for the fire inside me‏
thanks God for giving me the fire that makes me see life as worth living and enjoying it.
for giving me that love for everything about the air and beautiful things. the fire that burns inside me for painting.
it is more than passion.

6 jul 2015
regarding falling:
getting upset or discouraged if you fall is not the right attitude. after all, life is just a series of falls. the only thing that matters is that you stand after every fall.
or: it is not that you fall that matters. it is that you stand up after each fall.

31 mar 2015
the paradox of time
the thing with time is that, whenever you are enjoying something, it flies.
but when you are going through a hard time, or have to wait, it stops.

16 feb 2015
“Never argue with a fool, onlookers may not be able to tell the difference.”
― Mark Twain

29 oct 2014
the key to happiness and success is learning to like what is good for you and what you have to do.
this way you also will be enjoying all of that and it will be easier and fun.

26 sep 2013
words of wisdom
through life i have learned that the 3 magic keys to success and happiness are:
open your eyes;
open your mind;
and close your mouth.

19 june 2013
'thrust, but verify'
-Ronald Reagan-

25 march 2013
' Without feelings of respect, what is there to distinguish men from beasts?'


20 feb 2013
“It's easy to pretend expertise when there's no data to contradict you.”
-Seth Godin-

30 jan 2013
the idea is to die young as late as possible
-Ashley Montagu-

26 jun 2012
the mind grows by what it feeds on
-Ashley Montagu-

there are more things in heaven and earth, Horatio,
than are dreamt of in your philosophy.
-Shakespeare, in 'Hamlet'.

an old sage once told me:
it's useless to try to explain what human quality is.
if you have it, there is no need (to explain). you know what it is;
if you don't have it, you will never understand what it is.

14 jan 2012
'smart is he who learns from his mistakes;
wise is he who learns from other's mistakes'

'But I don't want to go among mad people,' said Alice. 'Oh, you can't help that,' said the cat. 'We're all mad here.'
-from 'Alice in Wonderland', by Lewis Carroll-

22 may 2011
we see what we want to see
(see below)

29 april 2011
In God We Trust. All Others Bring Data
-unknown- (but how true)

21 mar 2011
a man who knows his own worth does not boast; is not self seeking; will not domineer or force his own opinion upon others; respects his fellow man because he respects first himself.
-Pearl S. Buck-

20 may '10
it is much more fun to discover knowledge than to posess it
-William S Beck-

13 may 2010
see below: success!
also: tests on steps

11 may 2010
the good and the wise lead quiet lives

1 may 2010
are you enjoying it?
see below

1 may 2010
it is the knowledge that our years are limited, that makes them so precious
-Joshua Liebman-

24 april 2010

16 nov 09
Any intelligent man can make things bigger, more complex, and more violent.
It takes a touch of genius-and a lot of courage-to move in the opposite direction.
-Albert Einstein-

9 nov 09
One who thinks that he already knows, can not be taught anything new
-Zen proverb-

1 aug 09
Dream as if you'll live forever;
Live as if you'll die today.
- James Dean-

25 july 09
life is only as valuable as our determination to enjoy it
-Allan Cohen-

27 june 09
there are two kinds of people: those who are aware how foolish they are,
and the others. (and i add this as my own quote:the ones that aren't aware).
-old zen proverb-

"There are two things that no one can take away from you: your memories and your dreams".

My goal is to have fun. To enjoy what I do. I like to fly model airplanes, just for the fun of watching them fly. I fly small, light, slow electric rc from a grass field in little or no wind. Hand launch. Practice approaches-and catching them, too. That's it. I flew free flight and control line stunt most of my life. Some indoor f/f too.
I also like to understand what is going on, and to know what am doing. To design my own planes.
To learn what others are doing.


How I got started into R/C
Back in the 70's I ran a hobby shop/club, and one of my clients/students asked me to design a simple free flight sports model for the Cox .049 Babe Bee engine. It ended up as a high wing with 40 in. span, undercamber airfoil, and all solid 3/32" sheet fuselage and tail. It happened that at the same time I got one Ace single channel radio (the kind called Galloping Ghost), and I decided to install it into the plane and see what I could do. It was so much fun! Later, I got a Cox Sanwa 2 channels radio and built another plane (same basic, just enlarged the wingspan to 48") and powered it with a Cox .049 Black Widow engine. It was so popular at the field that I had to arrive at 6am in order to be able to fly it myself. After that, I began making kits of it. Then, on the late 80's I made an electric version (and sold many kits-now am retired), that in 2007 I adapted for the new technology. That is the one shown in the picture (taken in 2008), with yours truly, and am still flying it to this day, this time with a Scorpion outrunner motor and esc, a 2.4 Spektrum radio, and a 2x950mah pack. It weighs 400 grams and has 360 sq in wing area, and I practice touch and go's with it in our grass field. It is my largest model. I called it The Elf.

14 july 2011
growing young
in his book 'Growing Young', the anthropologist Ashley Montagu explains why some people stay young (or takes longer to grow old), and provides all kind of evidence, and he lived 94 happy years to prove that.
briefly, he says that what matters is what we tell our brains: as long as we keep learning, as long as we dream, stay enthusiast, positive, motivated by the desire to do something useful or help someone, determined to enjoy life, our brains get the message that our life has some meaning, that we are still of some use, therefore we are young. our neurones keep active and regenerating, just like muscles do when excercising.
i have found model aviation my way to do so, and i think that is the main reason why we all are into this hobby.
remember Hellen Keller quote: 'life is a daring adventure, or nothing'.

22 may 2011
we see what we want to see
i recall a movie 'the 6th sense', where the key sentence is: 'they see what they want to see'. and this made me consider that indeed, we all do. that's why is so important to be open to new (to us) ideas. to listen, just listen. things that we did not think-of before. when we learn about something, we know (or we think we know). through life, we go from 1 discovery to another, and see that sometimes what we 'knew' is no longer true. remember that the earth was flat, and the center of the universe? the best example is that thing about low reynolds, that i detail somewhere in this blog. am still meeting experts, fellows that have learned a lot of aerodynamics, who reject this idea without even reading about the work of schmitz. steps, turbulators, tips trimmed-and who knows what else is to come.
of course,the way we see life is another example: i want to be happy. so i see things under the positive attitude, and appreciate all that i have, and all that i ever had (my memories), and all that i dream of. enough to be happy. so i see happiness.
yes, it would be great to have more, but no matter what, we still have enough to try to be happy.
in such a happy thought...

13 may 2010
do you know what's the difference between being stubborn, and being perseverant?: success!
if you keep trying something that has never been done before, or that has been attempted and didn't work, and keep failing, they call you stubborn.
but if you succeed, they call you perseverant.
and it is in matters of the air that mankind has achieved goals that appear as impossible, because of perseverance of so many around.
it's thanks to all of you guys who pursue the unreachable star, that so many steps have been taken, one at a time, that has brought us to this unbelievable position in which we find ourselves today.
so, thank you folks, for all that you have done, and are doing, regarding this wonderful hobby of ours.

1 may 2010
are you enjoying it?
i met the great Steve Brown, indoor world champion (free flight), through the mail, but not in person. in those days, i was flying indoor and participating at the usic (united states indoor championships) at the futbol dome in johnson city, tennesee. i subscribed to the newsletter and Steve provided great insight of how to build a world class airplane and volunteered to provide advice, that i gladly accepted, and began corresponding with him-and learning a lot-for several years (that was 1994-97), then quit until 2006 (those were the years when i decided to learn to paint-more about this in a separate clip), and went to johnson city again. i was having a handful, 9 years away, loosing practice and the place where to test fly-and 9 years older-so i just concentrated on my getting my feet on the ground again for 5 days of 12 hours testing and competing, when, near the end of the 5th day, there was this announcement on the sound system: 'now let's say good bye to Steve Brown'. i did not know he was there until then! i rushed to the parking lot and reached him when he was getting into his car. i knew that there was just a brief moment to introduce myself and say a few words, and i said who i was, and how thankful i was for all the valuable help he had provided me, and the only thing he asked me was: 'are you enjoying it'? i said 'yes', and he said: 'good', and left.
if you think about it, enjoying what we have, what we are doing, and remembering all that we ever had, is what is all about.
so, paraphrasing Steve Brown: are you enjoying it?

some of my planes
9 june 2010
Aurora Boreal
the goal was to find an undercambered airfoil that could handle wind, with a model that looked like the rubber powered planes of yesterday. it started with a low aspect ratio (4) wing, and later a 6. both work well. the 4 makes smaller turns, and the 6 stays longer. the airfoil for both is 10%, 5%undercamber, max thickness at 40%, sharp leading edge. the results: a fast (to my standards), flat glide, that handles wind way better than all the other undercambered 1s that ever saw, and is very stable, too.
140 gr auw, 24ws x 6 (144sq in) red wing; 30x5 (150 sq in) yellow wing. all geodetic (union jack/warren truss, whatever) wing, tail, and fuselage. the motor is a c 10 (i got it from innov8tive-Lucien), 6/3 gws prop, 300 to 360x2 lipo; feigao 6 amps esc, 4.3 gr arrow servos,AR6000 rx, DX6 tx; 1mm carbon fiber (cf) pushrods, 1.4mm cf tubing-hollow (square) wing spars, 1.7 cf square tubing wing supports; 1-1/2" dubro wheels, landing gear is .055" piano wire. covering is all solarfilm: lw tissue on top of wing, clear solite on bottom, transparent solite on fuse and tail. glued together with ambroid.
it is the 1 with red fuse and wing, and yellow tail.

24 april 09
I fly small, light and slow electric rc planes, just for the fun of watching them flying, and try to land as close as possible to me. I fly at a nice grass field near Windsor, Ontario, Canada, (just across the river from Detroit, USA.).
Talisman is the first one that I designed on the 24" wingspan class, for the then new Park 180 outrunner motor (16mm dia, 10 grams). The total weight is 140 grams (near 5 oz), and has 144 sq in of area (about 1 gram per sq in, or some 5oz/sq ft). It cruises at 15kph (9mph), measured with the ‘How Fast' from Winged Shadow. It climbs at 60% throttle and cruises at 50%, for about 15 minutes on a charge, with some 6 to 8 flights. I enjoy practicing landings, with flights of about two minutes. I have been flying it for over a year, from below freezing (20F-or minus 6C) at dawn in Winter, to hot weather in Summer, whenever there is no wind. The radio is a Spektrum DX6 (AR6000, 8 grams receiver); the servos are Blue Arrow (4 or 4.3 grams each); the pack is a Hi Model 2x200 (16 grams) The prop is a GWS 6/3, although it can handle the 7/3-1/2 too. The pushrods are 1mm carbon fibre rods, and the covering is Litespan on wing and tail, and Microlite on fuselage and fin.The landing gear is 3/64"with 1-1/2" Dubro wheels. I use escs from Feigao (6A) or Tunderbird 9, and keep them well ventilated. The pack is installed inside, and is connected with a "jumper", so I don't have to open a hatch for turning it on or off. i use this jumper in all my planes with built-up fuselage. The wing airfoil is similar to a NACA 6409, 10% and 3% undercamber. It is the one on the picture, with yellow wings and blue fuselage.
Just watching it climbing slowly, silent, in the early morning, just an outline, is a great experience.
with this plane i tested turbulators, using 2 identical wings, 1 with, and another without turbulators, so i could exchange them and quickly compare the flight caracteristics and measure speed with a meter.
9 june 2010: i tried a new orange wing (5x30, AR6) with a sharper leading edge (and turbulators!), but the speed increased so much that it was not the slow plane that i wanted from the beginning, so i added a 3/4" fixed flap, that increased the area to about 170 sq in, and the flight slowed down to my expectations. flight times increased, but have not tried it on thermals, as i fly at dawn. the slowest plane i have had. for calm weather.

What works for me:

1 nov 09
Improving efficiency on small, slow airplanes.
From another dimension.
Once at a Fun Fly event, several fellows were watching my airplanes, and one of them said: 'Gee, they don't fly like the other small planes; they fly just like all the other, bigger ones'! And then he said: 'They look as if they are from another dimension'! That made me realize that there is, indeed, another dimension for small model airplanes, just like supersonic flight can be called same way: All the laws of aerodynamics have to be thrown overboard and start from scratch.
Small, slow airplanes behave different from 'standard' size (most of the planes that we see around), and have been considered inferior in performance.
But I have been testing several ideas that work, and i want to share with you.
They are controversial, so i want to ask you to wait until you read all before reaching conclusions. I will show all the data, sources, theory, but first let me tell you the results.
Let's see the easiest one first:
Regarding wing airfoil, usually there is not much thought about that: flat bottom for trainers, semi-symmetrical for basic aerobatics, or symmetrical for advanced aerobatics. All the thousands that have been tested and plotted are of no relevance. They are the same. Or, are they?
I have been using undercambered airfoils on most of my planes for getting longer, slower flights, as that is the way i like to see them flying, and we may get into details later, but the point that i want to mention here first is:
1.-The leading edge.
It is considered that all the planes have to have rounded leading edge, right? But i have been making it sharper and sharper, and getting better results in endurance and even in stability.
9 nov 09
When i started building model airplanes in free flight competition (duration), all the planes, small and large, were fashioned after the same clean, streamlined structure, with planked leading edge and spars inside of the structure, but years later, some fellows who built small models began winning with structures that had the spars on the surface and no planking on the leading edge. I followed the trend, because the planes were more efficient and stable and the structures were lighter. Without knowing, we were using built-in turbs.
I used add-on turbs for the first time from the idea of Max Hacklinger, a world champ. He used one line of monofilament nylon, 10% ahead of the leading edge, and at 10 degrees below the leading edge. I flew the plane first without and then with it. The flight time improved, and the stability too. When i returned to modeling in 2007 and updated my r/c electric planes from the 80's, i decided to play with that idea again. The first plane that i fitted with turbs was the Talisman. For it i had 2 identical wings, one with several turbs. They were made of regular sewing thread, and glued in place, one at the leading edge, and other 4 at 12, 36, 54 and 88% of the wing chord. Switching wings at the field showed right there the difference in behaviour, like speed, stability, angle of glide, sinking rate and duration (for duration i flew the plane one long flight with one charge of the pack, and then another flight with another charge with the other wing). With the turbs, the plane flew faster, the glide angle was more flat, remained longer in the air, and was more stable. The thing that impressed me most was that the speed was higher. And i measured it with the How Fast pitot tube, which provides very precise figures. ( you can get How Fast, from )
16 nov 09
By results.
It's way easier to sell an idea (especially if it is opposite to the common way) by results, than by explaining a theory that could work-or maybe not. That's why i started this by telling you that turbulators (for small, relatively slow planes) work.
The best thickness and position on the wing (% of the chord), are subject to experimentation, just like the shape and thickness of the airfoil, but in general, thin airfoils work better (have you noticed how well foamy planes fly?).
The leading edge: For my planes, a sharp leading edge has worked better, although for some other types a rounded one still does better (more about this later). Also, attaching a thread to the leading edge, to create turbulence, works better.
The position of turbs: After trying several positions, i have learned from some guys who have been here some time before me: the birds! The best results for me are: 0% (leading edge); 10, 30, 60 and 90.
Aspect ratio (lenght of wing): There are 2 types of birds: the ones that stay around into thermals, like condors (short, wide), and the ones that go places, like albatross (long, narrow), so it depends of what type of flight you like, to decide for long or short wing.
There is another kind of turb that works great, especially with foam: the step. On the upper or lower surface, or both (more about this below).

9 dec 09
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’).
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 Century, there was great interest in flying, and in Germany there was a scientist who believed that aeromodeling should be taught in grade schools. For that, he began making studies that led him to believe that small model airplanes behaved differently from full size airplanes, and even from large models. He even performed wind tunnel tests (at Gottingen) and reached some interesting conclusions.
His major discovery was that at certain (low) Re, things changed suddenly, and below that, all the known laws of aerodynamics were no longer effective. It seems as if everything reverses. Things like thick airfoils, rounded leading edges, smooth surfaces (especially the upper), that are good at high Re, become bad stuff, and the opposite becomes true (Could it be that’s why the turbulators and the steps work so well?).
The name of this fellow is Frederick W. Schmitz, and his work can be found in the archives of the Redstone Scientific Information Center in the Redstone Arsenal, Alabama.
It is entitled ‘Aerodynamics of the Model Airplane’, accession number N70-39001, (201 pages); NASA CR or TMX or AD number TMX 60976.
(By the way, in Germany he was awarded the Ludwig Prandtl Prize for 1941 for this work)
There is also another NASA Technical Memorandum from him, entitled:
‘The Aerodynamics of Small Reynolds Numbers’ NASA TM-75816 (45pages)
(This is not a condensed issue of the other one above)
With this scientific evidence at hand, the advocates of steps and turbulators may have what is needed to substantiate their claims, and also explains why these devices do not work on full size airplanes or large models, just on small models.
There have been some articles in magazines that briefly discussed the issue (and that do not give Schmitz any credit), another that got into great detail ( and that even if mentions him in the references at the end, he is lost among others, without explaining what his participation was). On the other hand, there is another (Model Builder, Feb ’75), by Ted Off, that gets into great detail and gives Schmitz all the credit, and even provides the sources to get the documents that substantiate this claim.
But the fact is that suddenly below Re 100,000, things deteriorate and don’t stabilize until reaching 40,000, when everything seems to be upside down. Lift has dropped, and drag has increased dramatically. So if you find your plane flying below Re 100,000, better consider the advice provided by Schmitz (it is when all these turbulators and steps work).
I grew up learning all that modelers had to know about aerodynamics, in order to be able to make a model airplane fly (those were the days when there was free flight only), even if I was well aware that between small and large models there were big differences that could not be explained by those rules, and it was not until I had Schmitz evidence, that I could understand why.
If you want, you can get all the details shown on those 2 studies, or just consider Schmitz conclusions.
On page 31 of his 200 pages study he wrote:
Comparative Conclusions for Model Airplane Wings
1.-Round nosed, thick wings are sensitive to Reynolds number and turbulence;
Thin, sharp nosed airfoils are insensitive to Reynolds number and turbulence;
2.-The lower the Reynolds number, that is, the smaller the model airplane or its speed, the thinner the profile must be, to achieve the supercritical flight state.
3.-To achieve the supercritical flight state it is sufficient if the upper surface flow is turbulent.
4.-The critical Reynolds number of an airfoil sensitive to Reynolds number and turbulence can be reduced by artificial creation of turbulence in the upper surface boundary layer, through:
a.-pointing the wing nose (knife edge);
b.-by a rough surfaced wing nose;
c.-most effectively, by stretching a turbulence wire or thread parallel to the wing’s leading edge.
He also advices the use of a constant chord (page 142) to reduce or avoid wing tip stall.

28 aug 2012
more on turbulators:
in his book 'aerodynamics', martin simons discusses low reynolds, and when gets into turbulent flow (pages 79-86), analizes turbulators and shows that with 1 turbulator ahead or at the leading edge the flow becomes turbulent, and this makes the airfoil more efficient,but then a separation bubble forms afterwards. where he fails is that he does not realize that this could be avoided by placing another turbulator, and then another, and another, at intervals. where they have to be placed is hinted by the birds, especially those that are good at soaring. if we look at the lines where feathers are located, they are around 20, 40, 60 and 80% of the chord. i have tested planes with 2 identical wings, 1 with, and another without several turbulators and measured the speed with the 'how fast' from winged shadow, and to my surprise the plane with the turbulators flies faster (40%), the glide is more flat, the flight lasts longer, and is more stable, so the turbulators keep the airflow turbulent and the efficiency improves-at low reynolds. another device that (at low reynolds) improves the stability (although creating lots of drag) by creating a turbulent flow, is the step, that has been tried extensively. this, perhaps due to that it is very thick, keeps the flow turbulent for a large % of the chord so does not need more than 1.

24 april 2010

i have been using turbulators for a long time, and more recently, for the past 3 years, performing systematic evaluations. i also got the scientific evidence by Schmitz that validates their effectivity, so i was just prepared for the next revelation:
Dick Kline did not invent the step. it was the unknown guy who first made paper planes with a fold along the span. Dick began playing with paper planes-just as many of us-but the difference is that he realized that the steps improved the flight, and brought this to our attention. they are known as 'Kline-Fogleman airfoils', although they are not airfoils; really they are devices that, like flaps, slots, slats, turbulators, are used on any airfoil, with the purpose of improving its performance.
at the time, he thought that they worked for all sizes of airplanes, although later it was learned that they don't work for full size airplanes, neither for the most common model airplanes (from .40 size engine planes and up), so they were largely ignored by modelers. still, there were some adventurous fellows that gave them a try on small size models, and learned that the planes flew way better with them!
the community rejected their claims, based on the tests done with larger models, and the fact that all the aerodynamics they knew, proved that they were exactly the opposite of what they wanted.
but steps work great on small models, and are ideal for foam planes, as they not only improve the stability and increase the lift, but are easy to install, and add strenght to the structure.
and with Schmitz studies, now we can understand why they work so well for small models.
recently, i began trying them. the 1st was a flying wing, called divinity (by apache pilot): swept back, tapered, with no dihedral, no reflex, and tips raised-sort of fins-but on mine i decided not to use the tips, so there is no side area (rudder, fin, end plates), with 1 step on top and 1 on bottom, at about 50% of the chord. from all that we knew, it should not fly, but it does. it required some steering now and then, so i added small end plates, about 1 inch at the trailing edge, tapered towards the leading edge. with them, it is very stable. then i built a plane with the looks of a bird, named 'dirty birdy'-short tail moment-(by boxhead), and used the steps, 1 on top, and another on bottom, and the plane flies fantastic.
for all that i know, for (small) planes flying below Rn 100,000, the steps make them much more stable and increase their lift. i still have to make many flights with all kinds of planes, measuring speeds, before reaching consistent figures, just as i did on the past 3 years with turbulators, but all the evidence shows that for foamies, they are the best thing to use. also we have to determine what is the highest Reynolds number at which we can use them and get the good effect. of course, it could be of great convenience if anyone can provide their data to add to the puzzle.
i am convinced that, even if he did not invent them, neither they work for large models or full size planes, by bringing them to our attention, Dick Kline made 1 of the greatest contributions to the world of small model airplanes.

13 may, '10
testing steps
here is so far, what i have learned about steps:
1.-stability: divinity (by Apache Pilot) is a foamie (6mm depron) flying wing 42" span, swept back, tapered, no dihedral, step on top and bottom at about 50%, no reflex, with tips raised. i tested in with no tips or end plates-no side area-nothing. it has to be steered frequently, but is controlable. then i added end plates of about 1" on top, and is so stable that i can catch it.
2.-performance depending on position of the steps: i tried 2 identical 'dirty birdy's (by Boxhead), short coupled foamies (6mm depron) 36" span-that look like real birds-1 with 1 step on top and another on bottom, the other 1 with 2 steps on top: both very stable; the 1 with 2 steps on top is a floater; slow; climbs fast on 50% motor, sensitive to wind; it's for calm weather; the 2nd, with 1 step on top and 1 on bottom is faster, wind does not bother it so much, takes more throttle to climb. it seems as if the step on top/bottom makes the airfoil behave like a symmetrical, whilst the 1 with 2 steps on top like a flat bottom airfoil (which they roughly resemble). there are more subtle details to test, like varying the % of the chord where the step is; the height of the step; if it is straight or serrated; the roughness of the surface; if combined with turbulators; the Reynolds number at which the plane flies (wing chord and speed)-or size of the plane.
perhaps the best results may be obtained by comparing 2 identical planes, 1 with 1 modification, and the other with another-and just 1 modification at a time. and of course, if you perform a test based on these ideas, bring it here or tell us where to see it.

25 july 2010
comparing turbulators and steps
what both have in common is that they produce suction and, for low Reynolds, that keeps the boundary layer attached to the surface, delaying its separation. also, if used properly, both improve the stability.
the difference is that turbulators work in subtle ways, meaning small changes go a long way. for instance, their location (% of the chord) and the number of them. i noticed the best results were similar to the 1 used by the birds: 0-10-30-60-90%. also, their thickness: i began experimenting with single thread (the kind used for sewing), and noticed improvement, but when changed to double, or thicker thread, it deteriorated, meaning it was too much.
and threads can be positioned with relative ease on almost any plane with a built-up structure.
turbulators work on the top surface, where the separation happens.
turbulators, if used properly, improve the efficiency, producing LESS drag. the proof is that the speed increases and the glide is more flat, and the planes stay longer in the air.

on the other hand, steps work using more drastic thicknesses, and the increase in stability is way more than with the turbulators. using them you can dare to build aircraft that wouldn't fly otherwise. an example is the divinity wing, that i have flown without fins/rudders/dihedral/reflex-but with steps!
but this comes with a penalty: the drag increases a lot.
steps are easier to implement on foamies, by just gluing an extra layer (and this increases the strenght, too), therefore are natural for them.
i may add to this as it comes to mind...

4 august 2010
that is, 'flying wings'. with steps.
i have built 3 wings so far, all with steps, and it has been a great experience.
i will get into details, 1 by 1.
all so far are based on the so called 'divinity' by Apache Pilot: same basic proportions, wingspan, area. all made of depron.
from what i have learned, it was Tony 65 x55 who started evaluating the step in model airplanes, and specially on a wing that he acknowledges is based on the Zagnut by Mike Glass (code name CenTexFlyer) that did not have steps. the wing by Apache was released some time after this, and is very similar to Tony's, and has steps, too. Tony provides in his very well documented tests all kinds of data and details, his reasoning for all. why and how. you will find it in: foamies-(scratchbuilt)- sticky Tony 65x55-the Kline-Fogleman modified wing -especially post 1, but all the others are worth reading. it was released on august 19, 2006.

my 1st wing was the basic 'divinity': 42:ws, 420 sq in, styrofoam (board depron), steps on top and bottom; end plates; glue was pu (polyurethane), rear mounted motor hk 1811, 18mm dia., 170 gr thrust; 15 gr with mount, prop adaptor and gws 6/3 prop. auw (all up weight) is 230 grams. needs full throttle at launch, which means that the motor is at the limit of its power. as it was too sensitive for my like, i trimmed down the elevons, from 1-1/2 to 1". it climbs and glides without change in trim. cg at 7-1/2". 2 cells 300 or 360 lipo, 4 grams servos, 10a esc, several receivers from around 4 to 7 grams. (it is 1 of my test beds for receivers). flies fine; stable even with some wind. see photo at the top of blog.

2nd wing: same basic planform, material, glue. it has a 1/8" sq spruce spar and is more rigid, in part due to the pu glue. 2 steps on top only. end plates. cg at 7-1/2". the motor, that is mounted amidships, is a 2211 from hk, 275 gr thrust with an apc 8/3.8, and weighs 45 gr with prop, prop adaptor and mount. auw is 225 gr with 2x300mah lipo, same servos/rx as the #1, and needs just half throttle at launch. lots of power. can do loops easily. very stable, too, and handles wind well. also photo at top of blog. as the motor is not at the rear, it allowed me to do some fancy tail, ala Horten, just for the kicks. on this wing i used carbon fiber (cf) to reinforce the center section: some strips, and some veil (paper thin, that looks like silkspan) with epoxy, and it worked great.

3rd wing: light weight version of #2; same basic planform and material, but for glue i was able to try uhu por, which is sort of silicon-based, and is flexible; very much like welders, but does not melt the board. the cf veil was in smaller amounts. the motor used is the mighty and light (14 grams) T1804 from tiger motors, that delivers 290 grams of thrust with a gws 8/4 prop, that allows it to climb at half throttle and do loops easily. compact, the 14 grams include mount and built-in prop saver, so the whole unit with prop weighs only 20 grams. the auw is 175 grams with a 2x300/360 lipo, 50 grams less than the #2. i still have to finish evaluation, but what i noticed is that it is more sensitive to wind, which is not a surprise. the idea is to learn how well it can do into thermals. very stable too.
these wings are hard to catch because they not only are fast, but with the sweep of the leading edge are easy to slip from my hand, so i have to make the approach higher and reach high for the catch.
for this #3 i have no photos yet, but i will get some and post them, too.
with all these wings i have used 6" Sig bubble canopies (p/n SIGCS006) not only for the looks, but to help making the hatch easier. the pack, rx, and esc are covered by the hatch. on #2 and 3 even the servos are flush with the surface and held in place by tight fit and tape. and on the #3 the canopy even covers the motor.

4 oct 2012
conclusions on turbulators and steps:
1.-stability increases;
2.-speed increases;
3.-drag is reduced;
4.-glide is more flat;
5.-duration increases;
6.-the most effective location is at leading edge;
7.-if using only 1, place it at the leading edge;
8.-when using more (besides the 1 at leading edgre), placed at certain % similar to birds, all of the above increases even more than when using only 1;
9.-thickness has to be small (like thread).

1.-stability increases a lot (more than with turbulators);
2.-drag increases a lot;
3.-speed is reduced;
4.-glide is not as flat;
5.-duration is reduced;
6.-location (% of chord), thickness, and adding more steps does not change performance noticeably;
8.-thickness has to be large. i mean, about 1/4" and up.

1.-turbulators: increase stability and efficiency; drag is reduced; speed increases; reynolds increases;
2.-steps: increase stability enormously and efficiency is reduced. drag is very large; reynolds is reduced

june 17, 2013:
i have been using turbulators for a long time. most of them with spars at the surface, as part of the structure, an also threads glued along several positions of the wing, running parallel to the span, over the covering. in recent times i built 2 identical wings, 1 with turbulators, and another without them (on the surface) and compared the plane's performance, even measuring its speed. now am working with sailplanes around the 2 meters (80") wingspan.
what i do with all my planes is to fly them without turbulators, long enough to become familiar with their behavior, and then add turbulators, starting with the 1 at the leading edge, then adding more along the chord, and watch the plane's behavior carefully with the addition of each 1
(there are more details somewhere here in this blog). but it is important to comment on the advantages of using them.
an example is what i did the past few days with my Thermalis (a 2 mt sailplane). i began testing it in calm weather, then little wind, and it behaved very well. then, 1 day, as the wind began to increase, i decided to keep flying and see how much wind could it manage. there was a moment when, at the time of stopping the motor, it took me some time to stabilize it to get into a glide. also, it lost penetration: just stood still in midair. so i began playing with trim and decalage, but things didn't get any better. then i added 1 thread turbulator at the leading edge, and the plane now has a smooth transition into glide, and has more penetration. it is now an all weather plane. that confirms my previous experience, that turbulators add stability, penetration and speed.

Stay tuned, there is more to follow…

16 may 09
I have learned that it is of upmost importance to know what to use, and where to get it.
I will start with construction materials.
The adhesive that I use for most of my building is Ambroid. It is the strongest I have ever used, and it's waterproof. Besides, if you need to remove or reposition a piece, you just dilute it with acetone and a small brush. It has been around for a long time, and has been available in tubes or can. I use it with a glue gun made of aluminum by Austin ( I got it long time ago). I hope they are still available from them or somebody else, for it is much easier to reach almost any corner with it. Besides, it is possible to thin down the cement to suit my needs.
It has been available at local hobby shops, but if you can't get it, you may try directly from the manufacturer. I have learned that it is tricky, so I will provide all the leads, that I learned through several phone calls. Here are the phone numbers: 603 352 2794, 802 885 9244, 800 367 5507.
They have several addresses: Springfield, Vermont 05156; Swanzey NH 03446, and you have to send a money order to: Ambroid Co, 272 Beaten Path Rd, Mooresville NC 28117.
If you get it in a can, don't forget to order solvent, too. It is very special and works much better than anything else.

Here are some of the terms that I use regularly:
esc=ESC=Electronic Speed Controller
o r=OR=Outrunner motor
lipo=LiPo=Lithium Polymer battery
ic=IC=Internal Combustion (engine)
lhs=LHS=local hobby shop
imho=IMHO=in my humble opinion

19 may 09
Balsa wood
After trying with several suppliers, I ended up getting my balsa from Jack Zimmer:
Specialized Balsa Wood, [email protected], 405 8th St SE, Unit 2, Loveland CO 80537
Phone 970 461 9663, Fax 970 461 9662
The price for one sheet of 1/16x3x36 is about $1, and if I want it to a certain weight (density, like 6#), he adds 100%, (about another buck), and if I want it to a certain grain (like 'c') he adds 100% of the original price (about another buck), so I end up paying some $3 per sheet, which is close to what you pay at hobby shops, and you get exactly what you want.
An example: I tell him I need balsa of 1/16x3x36 :$1; plus "C" grain : +$1; plus 6# : +$1= $3. The idea is to order about 10 of each size. The charges of s&h are about $13.
Besides, this way you don't have to spend time and gas searching for balsa at hobby shops.

21 may 09
I have been using lipos since the Spring of 2007 and am happy with them.
Lighter, smaller, I get longer flights, and you can get them at competitive prices with nicads.
Besides, lipos stay charged way longer, so can fly at any time, without the need to charge.
The key is the charger. I use the Cellpro 4 from FMA Direct ( . It charges and balances simultaneously up to 4 cells, and I can get readings of each cell whenever I want, to check their voltage, percent of charge, the amps they are taking.
I also use lipos on my transmitter pack (I own a Spektrum DX6), and I charge them the same way as the ones for the receiver.
If you want to use lipos for your transmitter, you must consider soldering 1 or 2 silicon diodes in series between the lipo pack and the transmitter, (see ‘flieslikeabeagle' sound advice at ‘my experience with lipos' post), in order to drop the voltage to 11.2V, as required by some manufacturers.
You don't have to do that, if you use a lipo pack with built-in balancer for transmitters, as you don't use the cellpro for charging it, just use the same charger that comes with the transmitter. Those packs don't come with individual wiring for charging each cell separately.
I prefer to use packs wired so I can monitor the charge of each cell, and charge them with my cellpro.

23 may 09
One more thing: If you are getting a cellpro, you may use it clamping it directly to your car battery, but if you intend to use it at home, you need a 5 amps minimum constant power supply.

26 may 09
This tinning flux is the best I have ever tried:
Petroleum-based, lead-free tinning flux, part number PTF800, made in the US by BernzOmatic, Medina, NY 14103, phone 1 800 654 9011, or

26 may 09
My planes
One of the planes that am flying is 30" span and 8 oz auw, 240sq in, undercambered airfoil, with Graupner folding prop. It cruises at 12mph, and I play launch-and-catch. It is perfectly safe, as I am using throttle lock, so there is no chance that if I move the throttle lever unintentionally I start the motor. And being so slow, it is so much fun catching it! Once it climbs to height (about one minute), I cut he throttle, flip the lock switch, and start the approach. As I use rudder and elevator on the right hand stick, this sets my left hand free to catch it, so I let it come a little bit to my left and just reach for it. I grab it by the landing gear left side leg. It looks easy and relaxed, but I have to make a perfect guess of its height and distance to do it.
Am enclosing picture of it. It is the one with folding prop, orange-red wings and blue fuselage. I call it Tramontano, an Italian word that Romans use for the gentle breeze that blows at Rome at sunset. And it is a breeze!


7 jun 09
jumper connections
As I fly small electric planes (the largest uses a 1000mah pack), I use a jumper made from a Deans 3 pins connector (p/n 1009) that connects to a base plate (included with the set) that I mount on the side of the fuselage.
Inside of the fuselage it is plugged on one side to the black (-) negative pole of the pack and on the other to the black (-) negative pole of the esc, with 2mm Horizon's e flite golden bullet connectors, (p/n EFLA 248), which I have standardized for all my connections between esc-pack-motor in all my planes.
This way, when I disconnect the jumper, the circuit is open (that is, there is no flow of current from anywhere to anywhere). No leak of power. Never.
I leave the pack fully charged in the plane for as long as I want (and the deans unplugged) , and I take it to fly in any moment, and it is fully charged, and just plug the deans.
No need to open the hatch or plug the pack.
I solder a small piece of wire to connect each pin of the deans plug at the other end, and then I attach to it a piece of thread that I tie to the plate, so when I disconnect it, it just hangs and does not get lost. It is there all the time.
I have been getting these deans connectors from, and they have given me great service.

26 jul 09
from servo to tail
in my small planes i use 1mm dia carbon fiber pushrods: they are lighter and more rigid than steel, and buying them from BP Hobbies, they don't cost me an arm and a leg. I link them to the servos with an adaptor made from a piece of .032" brass wire (20 gauge) that I got from the local arts and crafts store. I wrap the wire around a piece of wire or a twist drill of same dia of the pushrod, about 3 turns, then up and a z bend to fit the servo.
At the other end, i fit a piece of 3/32" x 1" alum tubing that i cut a slot along with the mototool. As it is too loose for the cf rod, i squeeze it a little with pliers, to fit the rod, and then enlarge the slot again. This is with the purpose of letting the epoxy run inside when gluing all the pieces together. Then comes a 3/64" brass rod, z bent to exit the fuselage, next is a threaded coupler (dubro # 111), to which i cut a slot along, and then a mini kwik link (dubro # 228). I make the control horns from clear plastic from bakery trays, not to save money, but because they are exactly the size and shape i need, are lighter, easy to get, cut, drill and bend. They don't bend along, but they do across, in case of a crash, and work great for me, but you may use the regular commercial nylon horns. I use tiny 0-80 screws (that i get from Micro Fasteners-they carry all kind of micro hardware, and are great in service and delivery) and drill, tap and cut back plates from .012" aluminum sheet from the local hardware store..
When all fits right, i epoxy the alum tubing, let set, then the brass z rod, then the threaded coupler, one at a time, to see that everything is going right. Once the rudder and elevator end is complete, horns and everything, and the servos mounted in place, i turn on the radio to make sure the servos are in neutral, and epoxy the adaptor to the pushrod.. I drill a hole for the pushrod into the formers between the servo and the exit at the tail, to get a more rigid signal. Sometimes, when the distance between the formers seems too large, i add a guide made from a piece of 1/16" balsa, drilled to fit the pushrod, and glue it in place at mid distance bet formers.
Last edited by phil alvirez; Mar 17, 2018 at 02:45 PM. Reason: update
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May 09, 2010, 05:54 PM
What could possibly go wrong?
nickchud's Avatar
Here's my motto:

Only the one who knows the taste of failure can truly appreciate the joy of success!
May 11, 2010, 04:24 PM
Registered User
Thread OP

it's beyond that...

Originally Posted by nickchud
Here's my motto:

Only the one who knows the taste of failure can truly appreciate the joy of success!
Edison did over 6,000 attempts before he found the right way to make the light bulb. he was not failing, just learning what does not work.
May 11, 2010, 10:21 PM
What could possibly go wrong?
nickchud's Avatar
Fair enough. Was it Goodyear who ruined his health and nearly poisoned his family finding a way to vulcanise rubber on his kitchen stove?
May 13, 2010, 10:54 AM
Registered User
Thread OP
Originally Posted by nickchud
Fair enough. Was it Goodyear who ruined his health and nearly poisoned his family finding a way to vulcanise rubber on his kitchen stove?
pioneers get all the arrows
May 13, 2010, 06:41 PM
What could possibly go wrong?
nickchud's Avatar
Yes, it's the second mouse who gets the cheese!
May 14, 2010, 06:20 PM
Onward through the fog.
Cybernaught's Avatar
Yesterday and tomorrow only exist in concept not in reality. All you have is "now". Don't waste it on BS. Build another model...

We think alike. The meaning/purpose of life is to enjoy it and that is all.

May 20, 2010, 07:50 AM
Registered User
Thread OP

it's an adventure...

Originally Posted by nickchud
Yes, it's the second mouse who gets the cheese!
but then again, William S. Beck said that
'it is much more fun to discover knowledge than to posess it'
Last edited by phil alvirez; May 20, 2010 at 07:57 AM.
Aug 07, 2010, 01:24 PM
springer's Avatar
Phil: just read through your blog, what a great life story! Also very interesting info on the turbulators and steps, Thanks for posting it!

Mike Spring

Hey, since you're just across the river from me, perhaps we can get together sometime to fly. (once I get my passport renewed, let it lapse when we only needed drivers license and birth cert to cross) If you haven't yet, perhaps check out the SEMFF thread in scratchbuilt foamies forum for what some of your "northern" neighbors are doing. (I know, bad joke, but Shelby township is north of Windsor!)
Aug 14, 2010, 03:59 PM
Registered User
Thread OP

flying together

Originally Posted by springer
Phil: just read through your blog, what a great life story! Also very interesting info on the turbulators and steps, Thanks for posting it!

Mike Spring

Hey, since you're just across the river from me, perhaps we can get together sometime to fly. (once I get my passport renewed, let it lapse when we only needed drivers license and birth cert to cross) If you haven't yet, perhaps check out the SEMFF thread in scratchbuilt foamies forum for what some of your "northern" neighbors are doing. (I know, bad joke, but Shelby township is north of Windsor!)
by all means: send me a pm and we'll talk the details. recently i had the visit of a great guy from france-the 1st 1 that dares to awake as early as me, and we had a great time flying and talking about so many things.
Aug 15, 2010, 06:27 PM
Onward through the fog.
Cybernaught's Avatar
Hey Phil,

We seem to have similar backgrounds. I flew control-line in the late 60's and early 70's. Stunt, like you, and limited combat. My favorite plane was the FlightStreak with a Fox 36X-BB or a trusty Enya 35 up front. I have had 3 sessions with flying model airplanes. The 80's had me into 2m gliders and limited electrics. This "go-round" is definitely the best of those times. Retirement gives me the time, cheaper electronics and materials gives me the way. Edna's affection and patience with my craziness, and my Flying Buddies on the internet give me the motivation and encouragement.

As we get older and our time shorter, we realize it's not a fair world. If it were, the bird wouldn't eat the worm, would it? If there is a God and a Heaven, as many are inclined to believe. They must have an infinite supply of foam and hot-glue and the most beautiful flying fields imaginable populated by all the folks who went before us and made this hobby so great. It's a comforting thought. I'm delusional, but it's still a comforting thought.

Keep on having fun. That is the true purpose and meaning in life. Let the "serious" folk continue to screw up society and fight their stupid wars because you can't stop them. They are insane and these "inmates" are running the institution! You an' me know better, so we just carve out a little niche for ourselves, away from it all, and play with our toys.


Nov 01, 2010, 12:07 PM
Primavera Pic Nic!
Ricardo Palacio's Avatar

Saludos Desde Mexico

Felipe ( Phil) what a great Story, and I am proud to be part of it........ My friend, so many memories "fly" around my head after reading your log, If I may let me add my personal Story as it is likked to a samall portion of Yours.

Guys, <I am From Guadlajara, the second largest city in Mexico, great flying weather by the way ; when I was around 14 years old ( I am 45 now) a good friend of mine Jorge mentioned that there was a groups of people Flying RC airplanes not far away from where I lived; and me being a fan of airplanes since very young, assembling mostrly Revell Static Models, was thrilled and went to see them the following Sunday, 8:00 am we were there, and we saw them, many of which were Elves, a nice High wing Trainer plane, Phil Received us with Joy and made us feel welcome, and he graciously answered all the ususl questions that a kid new to flying models would have; he also invited us to his store located in "Plaza Vallarta" ; so By Monday we were there , DISNEYLAND!!!!!, tes Cox 0.049 and 0.09 engines on display, Cox Sanwa radios ( 2 Chanels) and airplanes!!! YEs Airplanes for Display!!!!! Phil Showed them to us, and again answered all the quations, fuel, batteries, radio, EVERYTHING! man we were thrilled, I came back home and told my Dad about this experience, he was thrilled about it as well; I do not know if becuse of the airplanes or my excitement, maybe a mix of both.

Long Story Short ( if you can say that) I wanted one, Me and my dad discussed it but it wass too muchmoney; so we agreed that I would work on Summer Vacations for it, and if I needed more money that would be my B-day present; so I started workingpacking groceries at a Supermarket near home; an made quite some money,enough to buy one Kit of a High Wilg Elf, no engine nor radio though......... Well My birthday came and My Mom Da2 and 2 Sisters woke me up, singing happy Birthday my dad handed me a platic Bag containing My KIT! yes the ELF Kit that I wanted so badly! I was thrilled my heart was pounding , It was the happiest day in my life; Mon told me then that she had made Pankakes for breakfast ( My favorite) ; so I stood from bed and walked towards the Kitchen, I then Froze on my feet..... hanging from the Dinning Room's lamp it was; a Blue Fuselage Ready to fly Elf; Radio Included, cox Black Widow 0.049 engine as well; just waiting for me......... I literally started jumping,and so did my dad , he was the happiest man ever, and so I was, he made me very very happy!, I eneded up happily and rightfullly giving him all the money that I earned that summer to pay for part of it; and starting from there Felipe taught us how to fly and build airplanes, the experience has been with mee along my life as an example of joy discipline and respect; I will open a blog of my own, again, following my teacher Phil's example to talk about it, but I wanted to share this here so that I could express a little bit of the great Influence that he has hd in my life.

I am attaching a picture of me and my late Dad with the Zephyr, another model designed by Phil that I am intending to build myself very soon,

Phil, ( Felipe) thanks a lot and you know that you have my love and respect.

P.S. I Keep the Fuselage of that first Elf , I will restore it and Fly it again very soon......

Best Regards my friend!.

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