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Member postings for Mike Blandford

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

Thread: A question of physics.....
16/10/2016 22:58:49

Ted: I thought from your earlier posts you didn't think the 747 would take off, hence my question.


16/10/2016 22:40:52

Ted: What do you understand by "the speed of the wheels"? (You might look up the term "cycloid" before you answer).


16/10/2016 22:10:28
Posted by ted hughes on 16/10/2016 20:08:55:

No matter how fast the man on the treadmill runs he will always stand still (because the treadmill always matches his speed).

But if he will "always stand still" then his speed is zero, so the treadmill is also stationary if it matches his speed!


16/10/2016 21:40:42

Back to the physics!

What is the "speed of the wheels"? It seems to me there is a misconception by many to this question.

The only meaningful answer to this is "the speed of the axle" (equals the average speed of all parts of the wheel and tyre). Many seem to be assuming the conveyor belt is moving at the speed of the tyre where they contact each other.

It is a fact that, for a wheel rolling along a stationary surface without slipping, the point of contact of the wheel to that surface is also stationary. So, for those that are assuming the "speed of the wheels" is "the speed of the tyre where it contacts the belt", then the conveyor belt will be stationary whatever the speed of the 747!


13/10/2016 17:01:24

The 747 can take off.

If there is no friction (wheels/conveyor belt), then there is no force to oppose the thrust from the engines, so the the 747 MUST accelerate (Newtons first law).

If there is friction, then the top surface of the conveyor belt will drag the air above it along (opposite of wind sheer!). The resulting airflow over the 747 will then provide drag on the 747 to provide the force to oppose the engine thrust keeping the 747 in the same place (Newtons third law). This airflow will then also provide the lift to get the 747 airborne.


Thread: OpenTx - what is the fuss really about?
12/10/2016 16:06:35

BEB: The SBUS decoder using an Arduino I referenced outputs servo pulses at 18mS intervals, so is fine for analog servos.

Tom: If you have a wing with many servos, then, as Bob says, it is much easier if you only have a single connection to make.

Martin: You might try doing a 4 servo wing setup yourself, you will learn quite quickly doing that. Probably the main thing to 'get your head round' is to look at each channel, choose what you need to control it, then add a mix or mixes on the channel to provide that control.


11/10/2016 18:46:44
Posted by trebor on 11/10/2016 16:25:05:

If you purchased one of these transmitters and didn't get on with open tx could you re - install the original fry sky program ?

You also have the option of installing ersky9x on the Taranis. Ersky9x is another open source firmware that runs on a variety transmitters, and also has a PC program that makes programming the radio easier.


11/10/2016 12:29:40
Posted by Biggles' Elder Brother - Moderator on 10/10/2016 23:21:52:

The decoders cost £10.79 each, and the channel changer costs £13.49. So the all up cost of all the kit used in this post was just £35.07 and bear in mind only the decoders will go in the model, the channel changer is a one-off cost as it can be reused again on subsequent models. This FrSky kit is not expensive for the power it gives us I am sure you will agree.

If you are in to SBUS, and don't mind a bit of DIY, you might be interested in using an Arduino Pro Mini as a SBUS to PPM decoder. I've done one and the firmware is here: **LINK**.

This provides all 16 channels in one go, but you will need to aqdd the wires and connectors.


Thread: A couple of newbie queries about Taranis
05/10/2016 09:58:47

But he still needs to get the hang of short and long menu key presses in case something needs changing at the field.

Perhaps openTx needs one of the features I have on ersky9x. On ersky9x, if you hold the MENU key down while editing a value, the value changes in larger steps (typically 20) than 1.


04/10/2016 22:55:51

The default channel order is used when you create a new model, if you changed the default setting AFTER you created your first model, then that model will be using whatever the default was set to when it was created.

On the radio, to get to the MIXER menu, press MENU for a short time, then PAGE about 5 times.


Thread: FrSky Taranis - user chat
29/09/2016 14:14:38
Posted by Pitts Special on 29/09/2016 13:08:10:

It does say dsm2 though.

So not sure if it does dsmx?

Yes, it does DSMX as well as DSM2. It is a 4-in-1 module as it actually has the 4 common RF chips used for radio control on it, so it does a great many of the protocols in use including FrSky (V, D and X) DSM (2 and X) and Flysky. It enables you to use your 'proper' transmitter for many of the 'toys' that come with their own tiny Tx, as well.


29/09/2016 13:01:10

You might consider one of these: **LINK** , available ready made, see: **LINK**.


29/09/2016 00:04:33

If you are in the UK, then you may be better off going to T9HobbySport as they are a main UK FrSky dealer so you will get good dealer backup if there are any problems.


Thread: Dual Rates with 2 Aileron Channels
08/09/2016 17:18:00

Because the X8R supports 16 channels (directly on SBUS) I would advise using a channel above 16 as the 'virtual' channel, you might as well start at channel 32 for this.


08/09/2016 14:19:33

I'm not sure what you mean by "the usual way". Dual rates are best set on the inputs, not the mixes (channels).

So, you apply the dual rate to the aileron input (stick), then it is automatically used in any mix that uses that input.

Make sure you do use the input (and not the raw stick) in the mixes.


Thread: Scrap Box Wellington Bomber
04/09/2016 00:35:28

1200mAh ! You were lucky then.

I remember using an Astro25 on 16 1.0Ah GE cells, pre 1980!


Thread: Airco DH2
07/07/2016 16:22:26

I suggest having a good look over the parts and see if it may be repaired. I had a 46 inch aerobatic model suffer a mid-air. The wing was sliced in two and the fuselage badly damaged back to the leading edge of the wing, and split aft of that. It's now back flying again!


Thread: Which Battery.
22/06/2016 18:39:54

I would go for slightly lower capacity, but using cells capable of high current. I madeup a 4-cell pack of 25 Amp rated AA cells (from Component Shop) I use for the radio/servo supply in my Black Horse Mosquito. This handles 2 aileron servos, 2 flap servos, elevator and rudder servos and 2 retract servos.

They are not low discharge, so do need to be charged properly before going flying, but easily handle large currents.

The specific cells I have are not listed anymore, but there are some others with the same rating: **LINK**


Thread: Which taranis?
22/06/2016 18:30:29

It may well be not the actual power but how often the receiver sends a signal. One way, as I understand it, of meeting the EU regs is not to transmit too frequently. I believe the receivers don't transmit as often as the transmitters.


18/06/2016 09:13:15

The Taranis Plus does have the haptic as standard, it was the 'ordinary' Taranis that only had it as an upgrade.

The main displays are the same on the 'Plus and the X9E, the X9E has an extra (fixed) display.

The X9E has two extra sliders and spaces to add more pots/switches with the internal connections for them.


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