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: Bleriot XI|
The weather here in Iceland has not been very suitable for my Bleriot project lately. Never the less I’ve been able to do some flights. As some of the readers of this thread may remember there are two main tasks at hand at present. The first one is adjusting the CoG losing some of the lead up front and the other one is to select the best prop to be able to get the most out of the rather small SC30FS.
On D. Boddingtons plan the CoG is marked about 10 cm from the LE. To get the CoG to 11 cm I had to put about 600 gr of lead on the landing gear and therefore it was very difficult to get the model up to speed on the runway with the rather small engine. When in the air I had to use a considerable amount of up elevator to keep it level. I took Donald’s Fry advice and took off 25 gr of lead after each flight. Now I’m down to 425 gr so I must have had more than eight flights until now. The model still needs an up elevator, but considerably less than before.
During this time, I’ve only had two crashes, not counting some hard landings and minor injuries. Both was of course my own fault. The first one was fixed by re-gluing the landing gear but the latter one was more drastic. The reason for that crash was that once again I didn’t follow the rule of heading directly into the wind until suitable height is reached. If you allow the model to turn to early it will drop a wing and tip stall into the ground. (I needed three instances to get this; understand, practice and remember.)
The model is already fixed and ready for take-off once again.
I’ve been using 10*4 prop but as the engine runs in, it gets more power and I have now switched to 10*5 and by that I’ve got a little more speed for take-off.
It might be wise to try 9*6 or 10*6 as I could still do with a little more speed for take-off.
Now I´m off for Texas for a fortnight so further test must wait a bit.
Note to moderator:
Edited By Birgir on 03/07/2017 10:34:29
|Thread: Vintage Wheels|
I also went the DYI route to make wheels for my Bleriot.
There are some pictures on my web: **LINK**
If you choose English and click on the photos there is a little explanation.
Later I used neoprane cord instead of foam.
Edited By Birgir on 11/05/2017 22:04:18
|Thread: Spring is Here....|
The spring will also soon arrive here in Iceland so I went to the field this morning with my old trainer, the Keil Kraft Mini Super and practiced a few landing approaches just to loosen up my fingers for the summer.
Edited By Birgir on 30/04/2017 22:31:06
Edited By Birgir on 30/04/2017 22:38:55
|Thread: Have you passed the model flying/building bug onto anyone else?|
I guess you have to start early if you want to succeed, this is what we call "early intervention" in my line of work.
|Thread: Forum members' new models: Let's see them.|
When the weather is impossible and all your models are in a mint condition the only thing you can do is to design a new colour scheme for the field box and paint it.
Edited By Birgir on 02/03/2017 20:58:57
|Thread: Field Battery|
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.
Edited By Birgir on 18/01/2017 17:50:08
|Thread: Have you passed the model flying/building bug onto anyone else?|
No one yet, but I have eight grandchildren and I'm still hoping
|Thread: LED-lights DIY|
Good to hear Mannyroad
Here is a sketch of the switch free circuit design
Edited By Birgir on 09/01/2017 16:44:24
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.
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.
|Thread: buddy 6EX & T8J|
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.
Happy New Year
Have you thought of using Dual Receiver Controller:
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.
Edited By Birgir on 30/12/2016 13:57:00
|Thread: LED-lights DIY|
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.
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.
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.
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.
Edited By Birgir on 30/12/2016 09:13:06
Edited By Birgir on 30/12/2016 09:21:43
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)
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.
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?
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?
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
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.
|Thread: Bleriot XI|
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.
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.
Talking about scale
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.
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