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Member postings for Birgir

Here is a list of all the postings Birgir has made in our forums. Click on a thread name to jump to the thread.

Thread: Field Battery
18/01/2017 17:48:47

Hi Steven and welcome back

I’m an IC user and have been using the same Lipo 2s 4000mAh battery for my electric starter for the past three years. I almost never charge at the field and my starter battery only needs a recharge a few times a year.

If you are going to build your own field box feel free to download my excel sheet of an adjustable field box plan

You can see my starter and starter battery on the table.

B.

 

Edited By Birgir on 18/01/2017 17:50:08

Thread: Have you passed the model flying/building bug onto anyone else?
11/01/2017 10:11:53

No one yet, but I have eight grandchildren and I'm still hoping

Thread: LED-lights DIY
09/01/2017 13:34:52

Good to hear Mannyroad

Here is a sketch of the switch free circuit design wink

ms_light04.jpg

Edited By Birgir on 09/01/2017 16:44:24

09/01/2017 08:51:48

Thanks Denis

I went the DIY route and made three contacts on the fuselage. One is the negative, but the other two are the positive lead. When I put the wing in place, the positive connector for the wing lights bridges the two positive connectors on the fuselage closing the circuit for the tail light.

ms_light02.jpg

So now the mission is completed and hopefully I can start my spring flying a week or two earlier here in the twilight in the North.

ms_light03.jpg

B.

Thread: buddy 6EX & T8J
01/01/2017 10:08:42
Hi
 
In the Dual Receiver setup, you have as the name suggests, two sets of transmitter/receiver and in fact there is no information going from one set to the other. The neat trick is that one set is connected to the Ctrl of the Dual Receiver Controller via its receiver and you can, with one switch on that transmitter, control which set actually is flying the plane.
 
Congratulations on a smart and simple design Phil.
 
There is a video on RCModelReviews that explains this very well.

https://www.youtube.com/watch?v=-t1QmKa1LTI
 
Happy New Year
B.
30/12/2016 13:50:55

Hi Steve

Have you thought of using Dual Receiver Controller:

Wireless buddy box

I have put such a thing in my old Keil Kraft Mini Super using Futaba 6J and a very cheap Hobby King HK6S transmitter and receiver.

Worked fine for my only pupil in a single lesson. wink

B.

Edited By Birgir on 30/12/2016 13:57:00

Thread: LED-lights DIY
30/12/2016 11:43:06

Thanks Denis

I wonder what the price is for a CR2032 in UK.

Here in Iceland, a Duracell costs 3,6 pound a piece in the supermarket but I can get a no name brand in a low-price store for 18 cents a piece.

Enormous price difference but I can't see any difference in performance in my LED circuit. smiley

B.

30/12/2016 09:12:32

Good morning everyone

At last, the goods have arrived from China, a box with different coloured LEDs and a bag full of resistors, (1/4 W 120 – 910 ohm) so now it is back to bench testing.

I’ve decided to use three resistors, one for each LED (white, red and green) and all three LEDs in parallel connection to one battery pool of two button batteries, giving 6 Volts and 225 mAh.

led_circuit.jpg
In this setup the white LED is considerably brighter than the red and green but that is most likely because of the fact that those are different coloured LEDs.

If each LED is about 20 mA, three of them should use 60 mA and a 225 mAh battery pool should keep them lit for up to three hours. The bench testing showed just that. After 4 – 5 hours the white LED started to lose its brightness and this morning it was just a dim glow but the other two green and red seem to last longer.

led_test.jpg

Next phase is to implement the three navigating lights into my model, perhaps using the wing as an on/off switch, so that when the wing is in place the lights are lit but turns off when the wing is removed. For longer periods with LEDs off, I will place a plastic strip between the connectors to the wing as you often see in new toys that comes with batteries installed.

Comments and ideas, good or bad, are welcomed.

B.

Edited By Birgir on 30/12/2016 09:13:06

Edited By Birgir on 30/12/2016 09:21:43

24/11/2016 20:42:23

Hello again everyone

I’m enjoying this discussion very much and hopefully getting better and better understanding of electric circuits.

If I understand Denis’s diagram correctly the important feature in a parallel connection is that the resistor is on the lead before it splits into two or three or even more parallel connected LEDs. This would of course rely on that all the LEDS in the circuit where of a similar kind.

Could I use the metaphor of water running thru water pipes and the resistor being equal to narrowing in the system, only allowing a limited amount of water going thru, at least if the pressure is kept constant?

Then, one narrow part of the pipe would be sufficient to hold back the flow of water for the whole system.

But to keep pressing the laws of electric current I intend to use three different LEDs in my parallel connected circuit J, red, green and white. To be able to do that, I would have to have three different resistors, as Martin suggests, one for each LED that takes into account the different voltage of each coloured LED.

It might be wise to use two serial connected button cells giving 6 volts and 225 mAh

Now I must find a good guess for the voltage of each colour and find me a calculator to make use of Plummet’s, -eh Ohm’s law V = I x R

(PS. As you might have noticed English is not my first language so bear with me if my vocabulary is limited)

B.

24/11/2016 10:42:03

smiley

23/11/2016 20:33:09

Thank you all for very informative discussion

I have now ordered a handful of different coloured LEDs and another handful of different size ¼ w resistors from China. (Don’t tell Trump)

The specification is not very informative and most likely not the quality either, but it’s cheap and after all I’m not designing a life supporting system.

I’ve also done some bench testing using a 3mm white LED I saved from my granddaughter’s toothbrush, a button cell CR2032 3V from IKEA, using wires from a twisted pair taken out of a CAT5 computer lead but no resistor.

It has now been lit for more than 24 hours and it still hurts my eyes if I look directly into the beam.

led_test.jpg

So, judging by that, the amount of power in a button cell is not a problem.

Now my question is:

Is it right to presume that three LEDs in a serie will be lit longer but dimmer and three LEDs in a parallel connection would be brighter and have a shorter time span?

​B

22/11/2016 12:50:22

Thanks for the info

Am I right to conclude that if a LED uses about 20 mAh and a button cell is about 225 mAh it gives about 10 hours of light for a single LED and approx. 3,5 hours for three LEDs?

B

22/11/2016 11:09:25

Hi

I have been thinking about LED-lights and an easy way to implement navigation lights into some of my models. The reason I’m planning this is not only for decorative purpose but also to make it easier for me to be certain about the direction of the model in the air. It has happened, when the model is far away, that I’m not sure for few seconds and that’s not nice angry

Browsing the net I notice that many are advising to put a resistor with every LED and connecting to the receiver battery through the receiver.

My plan on the other hand, is to use a 3 volt button-battery to power the LED with no connections to the receiver battery. I’m planning to have a battery slot somewhere in an accessible place on the model where I can slip a button battery in, to turn on the lights.

My questions are:

If I’m using a 3 volt battery for a 3 volt (approx.) LED do I need a resistor?

Is it ok to connect a few LEDs parallel to one battery, for example a CR2032 3V?

Comments and ideas are welcomed.

Birgir

Thread: Bleriot XI
26/10/2016 14:04:15

I‘ve been thinking (yes, it does happen) about prop types and sizes. Earlier in this thread there was an informative discussion about prop sizes. After some testing with a very primitive testing method, rubber band and a ruler, I came to the conclusion that a 10*4 was giving the most pull and decided to stick to that prop size at least while solving other problems (CoG, weight and better wheels)

I understand that a higher pitch gives more speed and more diameter gives more thrust. So if I want to keep load on the motor constant, I can get more thrust with more diameter and smaller pitch, but that would, in theory, give lower speed. For my Bleriot and SC30FS it appeared in my rubber band test that 10*4 would work best. That was actually suggested to me much earlier, i.e. aiming for thrust rather than speed. (Thanks Jon)

I have been using nylon props, Robbe Dynamic, for all my testing and flying because they don’t brake easily and can survive a nose over or two. But from aesthetic point of view a wooden prop would look much better on a Bleriot and it has also been suggested that a wooden prop would max performance.

So now to the actual question.

If I go from Robbe Dynamic nylon prop to Turnigy Type A Beech Wood Propeller, can I use the same diameter and pitch?

Jon Harper has pointed out that those A type props run really fast and therefore I might use 11*5.

Based on my limited experience and knowledge I would think that 11*5 would put more load on the motor demanding more thrust and speed than 10*4, especially if it spins faster due to thinner blades.

I would welcome any explanation, comments, suggestions and tips about the difference between using wooden and a nylon propeller.

B.

20/10/2016 22:05:09
 
Following Donald’s suggestion, I switched 100 gr of lead with 3 * 25 gr and took off.
 
Everything went ok but it didn’t seem to make much difference. So, I landed, removed 25 gr more and took off again. Everything still ok, a little change for the better, not as much elevator needed to maintain constant height.
 
Next decision: remove another 25 gr. Now, my courage was increasing and I had a new idea. How about different style of landing. Until now I have always landed on half a throttle, flying the plane in, aiming for a smooth landing. What about having the motor idling and gliding in for landing?
 
Well in just a few second I realized that Bleriot XI is no glider. Under cambered short and wide wings are not at all similar to gliders wing. The model came down more like an elevator than a plane.
 
When landed, I realized that somewhere before, I had seen a picture of similar landing.

scale_landing.jpg

Talking about scale smiley

Luis Bleriot’s first landing in UK was probably very similar to mine.

Only minor damage and already fixed, further adjusting of CG must wait another day.

B

17/10/2016 09:05:40

Thanks Donald

But I‘m a little confused. When you say “too far aft” do you mean “too far forward”?

I will take 25 gr. out at a time.

smiley

B

16/10/2016 18:26:52

Today we had yet another calm day in Iceland, - what is the world coming to.

I did some more practice on my Bleriot and now I have two tasks at hand.

The first one is fine tuning of my SC30FS. When I run it full throttle for some time it tends to take a brake and stops delivering full power for five to ten seconds. If I relax on the throttle it picks up again. I’ve tried to lean the mixture, quarter of a turn clockwise, but that increases the problem. If I make the mixture richer, turning counter clockwise I’m not getting as much power. Does anyone have experience of this? Could this be something that disappears with a little more running in?

The second task is trimming. As I´m getting better at controlling the model in the air I now have started to trim for levelled flight. It looks like the model only has one speed, full throttle, and needs 5 degr. of up-elevator to keep constant height. Considering that the elevator area of the split stabilizer is quite big, (68 sq.in.) this is considerable amount of up-trim.

There are probably two main factors to take into account. The first one is the down thrust of the motor. I haven’t been able to test this properly but it feels like the model slows its speed and loses height very rapidly when the throttle is pulled back, not pulling up as I would expect if the down thrust would be too much. It is as per D. Boddingtons plan.

The second factor is the Centre of Gravity. At present I have got 600 gr of lead up front and the CoG is about 12 cm from the LE. On D. Boddingtons plan the mark is about 10 cm from the LE. Would it be right to presume from the flight experience that the ballast is still a bit too much and would be ok to move the CoG one cm further back or so?

My intentions now are to remove 50 or 100 gr of lead and have a try.

Does that sound sensible?

Any thoughts, comments and ideas are welcomed!

B.

 

 

 

Edited By Birgir on 16/10/2016 18:45:35

14/10/2016 15:04:52
Hi everyone
 
Today there is a fairly calm weather in Iceland, about 5 m/s, so I decided to practice a little more with my Bleriot
 
Better tuned engine and also more running time has increased the power a bit but it still is very scale like. I have also put neoprene tires on the wheels – thanks for the tip David.
 
The wind was a bit swift and the model was swept side to side. The take-off went very well, I have taken PatMcs advice to mix the left stick 30% to the right rudder stick and it works well.
 
When in air the rudder and the split elevator do have a very good control over the model. Even when a sudden side gust almost rolled the model 45 deg. full rudder could level it off and for a short time it looked like the model was flying sideways, at least compared to the ground.
 
I hope there will be more opportunities to practice later this autumn – this is very much fun even though the wind is about the limit the model and I can handle.
 
B.
 
21/08/2016 11:34:00

Hi

I ‘m still doing some exercise and learning to control the Bleriot. I’ve realized that in the first tries one of my mistakes was to use the elevator to keep the fuselage wheel on the ground. My thought was that keeping the fuselage wheel on the ground would help the control on ground and at the same time ensure that the model would not nose over. I was also worried about the tail being set too high so the take-off incidence of the wing would not be enough.

I have now learned that it is better to relax on the elevator, keeping it neutral on the runway. The model soon lifts the tail getting into the correct fuselage datum line (I think). There is no danger of nose-over and it is much easier to get up speed. When suitable speed is acquired a small pull on the elevator stick gets it airborne. When in the air it is very important to keep the model straight into the wind using the rudder against the direction the model tends to go to. If not, it will drop a wing and go back to the repairing table. This is where I am at the moment. No major damage, just small fixing here and there.

Any comments and advice are very welcomed

B.

10/08/2016 09:11:39

Well, it still felt at least a bit stressful 

Actually I flew two flights. The first flight I left Luis on the ground (56 gr.) but added 100 gr of lead up front, having total of 700 gr. ballast. The power was very marginal and it felt more of a problem to keep the nose up rather than being tail heavy.

So the next flight I skipped the extra 100 gr and put Luis in again (about 2630 gr total, I think). I also noticed that the elevators seemed to have moved on their axes. I corrected that, tightened the screws holding the middle and took off again. That is the flight in the video.

After not so graceful landing I realized that the elevators had moved again and where not in line with each other. The aluminium pipe is not glued well enough in the elevators and can be moved. There were just a minor damage to two of the balsa pieces in the side of the fuselage.

The lesson learned is.
a. CoG about 12 cm from the LE looks ok at present
b. The power is marginal but ok with 10x4 prop
c. The split elevator does its job well, but needs fixing
d. This was great fun!

Birgir

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