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Member postings for dave windymiller

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

Thread: Simple arduino altimeter
24/05/2019 20:38:54

Here it is, not the best written code im sure but it works!


 #include "U8glib.h"
#include "BMP280.h"
#include "Wire.h"
#define P0 1013.25 
BMP280 bmp;

// OLED Type
U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NO_ACK);

char sT[20];
char sP[9];
char sA[9];
char sA_MIN[9];
char sA_MAX[9];
char sA_DIFF[9];
char sA_NOW[9];

double A_MIN = 0;
double A_MAX = -1000;
double A_DIFF = 0;
double A_NOW = 0;
double cal = 5.0;
double count = 0;

void draw2( double A_DIFF, double A_NOW) {

  dtostrf(A_DIFF, 4, 0, sA_DIFF);
  dtostrf(A_NOW, 4, 0, sA_NOW);

  u8g.drawStr( 5, 10, "Alt NOW: " ) ;
  u8g.drawStr( 70, 10, sA_NOW);
  u8g.drawStr( 5, 40, "Max" ) ;
  u8g.drawStr( 5, 60, "Alt Ft:" ) ;
  u8g.drawStr( 70, 60, sA_DIFF) ;

void setup() {
  if (!bmp.begin()) {
    Serial.println("BMP init failed!" ) ;
    while (1);
  else Serial.println("BMP init success!" ) ;



void loop(void) {
  double T, P;
  char result = bmp.startMeasurment() ;

  if (result != 0) {
    result = bmp.getTemperatureAndPressure(T, P);

    P = P + cal;
    if (result != 0) {
      double A = bmp.altitude(P, P0);
      A = A * 3.28084;

      if ( A > A_MAX) {
        A_MAX = A;

      if ( count == 0 ) {
        A_MIN = A;
        count = count + 1 ;
    A_DIFF = A_MAX - A_MIN;
    A_NOW = A - A_MIN;

      do {
        draw2( A_DIFF, A_NOW);
      } while ( u8g.nextPage() ) ;
    else {
      Serial.println("Error. " ) ;
  else {
    Serial.println("Error. " ) ;



Edited By dave windymiller on 24/05/2019 21:01:20

Edited By dave windymiller on 24/05/2019 21:02:12

24/05/2019 20:24:18

With the revision of restrictions around airports changed recently, our club, previously inside the FRZ now thankfully finds its self outside ! In theory we can now fly models greater than 7kg but we need to change the club rule. The limit of 400 ft is the sticking point for the club committee.

I decided to look for a simple altitude recording device and found this simple arduino project  Standalone-Arduino-Altimeter. Only three components & around 10 quid to build.

I decided to build one but decided the software need tweaking to suit. I wanted an altitude above launch. As it stood, it indicated pressure temperature and altitude with altitude min and altitude max. The altitude was dependent on both baro pressure and locality height. It could be possible to calibrate it but this would vary with weather. Also 2 decimal places was too much.

My software simply sets a zero altitude on power up/reset and a maximum in relation to this datum . Ive also set it to feet rather than meters!  The bmp280 chip is apparently good for around +/- 3ft 


My device mounted in a small plastic box 50mm X 35mm and weighs less than 20g. The plastic screw is mounted above the arduino reset button to act as a button to reset the altimeter to zero before flight.

If anyones interested i could post my revised software!


Edited By dave windymiller on 24/05/2019 20:32:01

Thread: Hex Drivers
01/05/2019 19:59:52

I often use a 1/16 hex key instead of a 1.5mm hex in m3 grub screws as they are a few thou bigger and less likely to slip. Where possible i also change short m3 grubs (say 3mm long) for 4 or 5mm which have deep holes and more surface area for the key to grip!

Thread: Where's all the stock?
28/04/2019 20:57:36

I was in my LMS yesterday and was shown the ripmax on line catalog for dealers. Something like 200 types of artf models listed, 4 in stock!

Thread: Unusual full size aircraft that would make something different to build!
22/04/2019 21:32:55

Im progressing towards a Mig 1.44 for two VT80 turbines. There is only one Mig 1.44 and this resides in a museum having flown only a few times after the Russians opted for J10 design instead. Having started with a balsa profile model the next step is a 60 powered model of a Mig 1.42 "LFI" at 1/12th scale. The 1.42 was the single engine version but this never got off the drawing board at full scale. This model was to have a turbine but i decided my vt80 was too big for it so went for a 65AX just to prove it (may convert to a smaller turbine if its a success) . Its at the painting stage so will hopefully fly this summer. The model of the 1/10th scale 1.44 "MFI" (or flatpack as its western codename) just needs a glass fuselage casting. The bottom pic shows the wings attached to the plug used for the mold!




Mig 144



Mig 144

Edited By dave windymiller on 22/04/2019 21:58:29

Thread: Batt, problem mobile drill
12/02/2019 21:18:34
Posted by Gary Manuel on 01/02/2019 11:06:18:

You could always do something like THIS.

I'm very happy with the results.

+1 Wish i had thrown away the nicads years ago. It gives new life for a tired 4s battery no longer any good for flying! I go for weeks between charges now and its always ready to go, never flat.

Thread: Ideas for articles in RCM&E
27/01/2019 19:20:33

I for one enjoyed the article on Arduinos and the servo exerciser. For many years ive played with PIC chips and as such i ignored alternatives until this article.

I knocked up an arduino to play with servos, flashing LEDs and the like and was amazed how simple the user programming is with all the hard work tucked away in the background. Far simpler than PIC chips and hence less time programming and more balsa bashing.

Why the interest?

I have built a 60 powered mig 142 (1/12 scale) as a test bed for a bigger mig 144 (1/10 scale) but the problem with these canard jets is the rear u/c is so much further back from the models cg which makes take off difficult. As the U/C retracts forwards i plan to try and partially retract the rear electric retracts and then stop them so they are moved forward a couple of inches. This sounds like a job for an arduino circuit to cut and later restore the power to these retacts in flight? Then theres U/C door sequencing, something else to try?

If this works, the same will be tried on the 144 (twin VT80 turbines planned). I know of one in Germany that was destroyed on its maiden due to c/g and u/c positioning causing a violent ground loop on takeoff. I want to try and avoid this!

I look forward to the rest of the series on arduinos.

Dave Windy Miller


Mig 144


Edited By dave windymiller on 27/01/2019 19:35:23

Thread: Mosquito Cof G
31/12/2018 16:36:50

Thanks all

Ive reduced throws and managed to shed a few grams from the rear and will decrease the reflex on the ailerons and try again tomorrow.



25/12/2018 20:02:25

My Mosie had a habit of tip stalling. I now have reflex ie up aileron on both wings and reduced down throw on ailerons. It is far less prone to dropping a wing now.

The last few times of flying its behaved like it had a rearward c of g with a lot of pitch sensitivity. Ive added some 200g of lead to the nose and have minimum throws on elevator and 40% expo but still its a roller coaster ride.

Can upward reflex in the ailerons cause or increase this effect of pitch instability?


Edited By dave windymiller on 25/12/2018 20:03:39

Thread: cutting foam
21/12/2018 21:46:25
Posted by alex nicol on 18/12/2018 23:02:26:

Ive just been messing about with a home made foam cutter powered with a PC PSU controlled with a dimmer switch. I've tried various types of cutting wire from 0.27 - 0.6 nichrome wire ti lay straight control line wire. ideally I'm looking to cut a 30" span section.

Has anybody else tried this and if so what wire/PSU did you use

A PC power supply is switch mode type and powering it via a light dimmer which carves up the AC, sounds like a recipe for a distressed power supply! A dimmer would work much better on a simple transformer.

Ive had good results using guitar strings which is handy when you have a guitar too!



Thread: BT internet email
02/12/2018 12:53:28

We got superfast from BT but the nearest the fibre cable comes to our house is 1/2 mile away. Its copper wires the last bit and it works fine.

Thread: Ionic wind power
25/11/2018 22:27:31

That reminds me of shuffling feet and zapping the metal bookshelves in the school library over and over until they were fully charged.

We then sat back to wait for a victim to choose a book and BANG with a 1" bright spark of lightning. How we laughed. They eventually earthed the shelves to stop this!

Thread: BMFA?
01/09/2018 20:59:28

A mate of mine lost his cox 010 powered free flight model last Saturday night at the nats. After contacted the bmfa he discovered that it had been handed in to them by some kind person. The BMFA built a box around the model and posted it to him, arriving Thu (i think), totally unharmed.

Well done those involved. I for one didnt expect he would see that again.

Thread: Covering advice please
23/08/2018 21:48:53

Once i tried oracover (or profilm) i never looked at solarfilm again!

Thread: Super rare Rojair kit - Pre production ME109 with slight fire damage
19/08/2018 11:03:42

Thankyou all

18/08/2018 21:36:56


Making some progress.

I decided to add a better pilot than just the usual head and shoulders so i got one from real model pilots. Had to shrink him in height as i couldnt use the full depth



Not totally to scale and once the canopy is in plenty good enough. The canopy didnt have any form of frame cast in so i had the bright idea of casting a fibfreglass shell around the outside of the canopy then cutting it out to produce a more realistic frame. Note the whole of the rear of the canopy opens on a 109G




Finished spinner



The thing i love about foam wings is the speed of progress once the wing skin is in place. 2 days work for a nealy finished wing.


The flaps on a 109 are quite complex with 3 parts. The flap thats about mid span will be lowered by a servo in the wing. I can also make this flap act as an aileron if necessary as the now scalish aileron is quite small. The inner flap has an upper and lower section which is part of the radiator duct and these seperate as the flap lowers. The top will be driven bt a torque arm and the two halves joined by a linkage that increases seperation as it lowers (hopefully!)


stay tuned

Dave windy Miller

Edited By dave windymiller on 18/08/2018 21:39:09

Thread: Rudder and tail wheel control horn
15/08/2018 13:20:25

Unfortunately I cant show any photos as its hidden inside the fus until its next crash!

Im not sure of the plan its built from but I think its an adapted version of the BH plan. Its 69" span and the fus is in two sections, the rear half is stepped behind the wing and behind the cockpit. Its got 2 X la40s swinging 10x5 3-blade props from master airscrew (about 3 quid each from hobbyking via hongkong!) .

When it all goes well its beautiful in the air. I have the ailerons up a few degrees to prevent tip stalling plus both engines point outwards a few degree to hopefully minimise yaw on a dead engine. Its got no flaps! It did have a clear nose section but since its first crash, its now the fighter solid nose version(never got round to adding cannons). The eagle eyed would spot the wrong canopy for the NF version!

It became a labour of love after 3 rebuilds!  I felt I owed it to Tony Bowler (RIP) who built it.

Edited By dave windymiller on 15/08/2018 13:25:41

13/08/2018 22:27:53

Be warned.

If a tail wheel can cause the rudder arm to slip, 100% it will on the first bump. The mosquito flight will be very short! ask me how i know.

I bought this nice model off the estate of a fellow club member but this one fault has been its downfall (3 times). Each of my improvements proving inadequate.

The grub screw was swapped for a cap head screw but even this didnt give enough grip. Loctte also failed. Mine has now a cap head screw locating onto a flat on the shaft, holding a solid brass arm and has been silver soldered too.

Best solution is independant tail wheel servo which i will try if theres another iteration of this problem!

The mossie now sports an easy to repair night fighter black with home made spinners!





Edited By dave windymiller on 13/08/2018 22:32:59

Thread: Rudder trim backwards on SG14 (only on one model)
21/06/2018 19:30:17

Thanks for the advice thus far.

Just found the issue. Pressing Sys on the jog dial displayed the transmission protocol ie fasst-mult and not the SYS menu. It was acting the same as pressing the rtn button.

After playing more with the rotary jog switch, the sys button started working properly (dirty or dodgy sensor??)

Now i could get in to this long forgotten menu. i could see rudder was set to reverse in the "H/W set". putting this to normal and reversing it inthe linkage menu sorted it. Obviously i must have done this when i first got the radio as it was "model 1" that had the problem!.

Sys isnt something i normally need to go into and i hadnt missed it at all!

Despite having a degree in computing electronics this tranny still has the power to purplex me.

20/06/2018 21:25:24

Im probably being dumb and missing something simple but my rudder trim operates opposite to the stick on one model (all others are fine). I could cure it by copying another similar model but i would like to know why. Its a model thats not flown for many years so this may be an old problem i never spotted before.

Rudder servo is not reversed, on rx output 4 (FRSKY 8 ch), no mixes and nothing else trying to drive output 4. All rates and endpoints are normal (no negatives) Rudder is J4, trim is T4. Cant see anything that may do this!

Any thoughts?



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