One Small Step-Motor for a Man #2

Let's look at connecting an RC transmitter to a receiver. And take the gum out of your mouth.

First thing to note that ~ designed by nerds for nerds ~ it's not obvious how to turn it on. It's either of the two chrome switches in the middle. Don't ask why there's two... just be happy that the light comes on.

First thing to note is that the Futaba 'Secret Squirrel®' HOME/EXIT key necessary to return to the system screen is that chrome strip on the left, just below the side-stick.

The side-stick here controls the throttle, and as a safety feature this should be left closed (lower stop) throughout, which is to stop people from inadvertently turning on things so that the motor and propeller elsewhere take out a bystander's finger.

Of most interest here is the TX (transmitter) voltage top right. Run this down and the cat will sail off into the sunset of its own accord.

Ignore the SYSTEM menu, and the MODEL select. The latter allows nerds to use the TX with a range of different types, whereas thankfully we'll be dealing with only one.

Instead press the LINKAGE menu-pick, with a side order of fries. With more options on this next screen than a Chinese takeaway, we need only SYSTEM TYPE.

According to 'Chip' on the FUTABA video, five time aerobatic champion, our receiver is an 18-channel FASSTest type, with built in telemetry like an F1 car. This means it can send data back to you like the afore-mentioned onboard voltage level.

Pressing this, and then the LINK button, should connect the receiver. Doing this while the RX was powered up, the TX was not a happy bunny ~ may just be me, but you may have to power up the RX after initiating the process.

Once this is done ~ you'll agree it's not rocket science ~ the screen below appears.

Note that it provides the Receiver ID, which sadly cannot be personalised. Also shows the voltage (3.8V and not the 5.0V I guessed at tho' the RX will run on a range of some three to six volts).

It also provides the BFS voltage, which is not the big friendly giant but the status of the batteries powering the receiver. Should it drop below par, the throttle will shut the power down and stop the boat.

D/L is download interval for data, you can speed this up at the cost of the control data being sent up-link, but like... who cares?

More exciting is the fact that it says SINGLE up there, which can be switched to DUAL or DIVORCED.

This affects us, as it affects the TELEDRONE as I'd like each pontoon to be a snap-on module that's self-contained with its own battery, RX, ESC, motor and propeller... and this may be a means of sending control signals to an RX on each drivetrain.

It's not knowing that makes life exciting, just like Christmas Eve.

But turn it all off now, and go to bed:

Hobbywing X-8

Referring to the airboat seen in the previous post-but-one and speculation regarding the motor in use, it turns out it was the above. I guessed looking at it that it was on a par with T-motor's U13 that I've used on unmanned drones, though in fact it is nearer half the power... which is good news for the prospects of an uncrewed cat in terms of its potential speed and the required power.

(Note the X-8 integrates the speed controller and indeed supporting arm in a package, much like how personal computers evolved from separate electronic components into the laptop I am using here today. Expect this to be one of the more exciting trends in 2025, but don't whip yourself into a frenzy over it...

One Small Step-Motor for a Man #1

... one giant leap for drone-kind. This is an RC receiver, and whilst they come as small as a finger-nail nowadays they still need a pair of antennae that any cockroach would be proud of.

The receiver operates like all RC currently (geddit?) on 2.4GHz, or UHF radio-waves. I last used these as a cadet in the RAF, because the military use UHF communications whereas airliners use VHF.

(I was shocked to discover that TV remotes operate at over 5 GHz ~ or SHF ~ tho' they use infrared light which to my mind is cheating.)

Note the dedicated battery ~ whose voltage I've forgotten but I do recall electronics runs generally on 5V DC ~ which has to be plugged in to the last port on the receiver, marked 8/SB because there are eight of them and SB because it's a serial bus that requires only a single wire. You remember those printer cables that looked like strips of lasagne? They were parallel buses, which have fallen out of favour.

Can I connect the plug the wrong way around? "Yes we can!" as Bob the Builder would say, and the only way of telling is that the green LED power-up light remains off.

Note there is a socket at the end of the R7008SB (catchy name, could be a BMW) for a voltage meter that transmits voltage back to the operator holding the transmitter. It doesn't say WHOSE voltage it is transmitting, as there may be separate batteries for the receiver and for the motors... you're just supposed to know, or risk ridicule at the annual RC-nerd convention over ginger beers.

Why though is knowing the voltage important? For you can run the motors and all else onboard from the same battery-pack, but then you need a distribution board, known to electrical engineers and pilots as a 'bus'. (And if you pronounce it 'bus' not 'buzz' you'll be paying for the ginger beers all night).

Well the Achilles Heel of the state of the art batteries that the modern world runs on is that if the voltage falls below a certain threshold i.e. flat, then you've to throw them away. Phones, cars and laptops use a BMC (Battery Management Computer tho' it used to mean British Motor Company in the age of empire) to prevent this from happening.

Tho' whilst you're driving the TELEDRONE, that BMC is going to be you.

© Colin Hilton, BMC.

The Joy of Esc

Another in the series of 'If I can do it, anyone Nobel prize-winning physicist can'.

So with a new year upon us, it's time to go large or go home. Our first objective is to connect an RC transmitter, receiver, electronic speed controller (ESC) and motor in a meaningful way.

Accordingly I provide the instructions from Flame (bad name for an electrical device if ever there was one), to see if you can figure it out before I can. It applies to all known Flame ESCs in the universe, but turning to your text-books note that ours is the 80A.

Top tip ~ modern motors use the ESC to draw a DC current and deliver it like an AC so as to drive a motor that no longer requires a split-ring commutator as it did during my physics classes.

Top takeaway ~ the ESC essentially governs the power delivered the motor by virtually throttling it. As you may recall from those same physics lessons, restricting electrical currents invariably produces heat and therefore ESCs have proven MORE reliable when operating at full-chat (much like reciprocating aero-engines are designed to do, unlike their cousins in automobiles), because this is when they're needing to work less hard.

N.B. It's not the most legible, tho' the bare bones also appear here:

https://robu.in/wp-content/uploads/2021/10/Flame-ESC_merged-1.pdf

Hydrofoiled

If you've nothing better to do at five in the morning, then there's nothing like surfing YouTube videos in search of the state of the art. This incidentally is testing US style: sunshine, open water and open minds as per the rain outside, strict prohibitions and curmudgeonly old men with their sad boats in their sad garages in the UK.

And that's just me I'm talking about.

But this guy's ThinkFlight channel features among his many experiments his efforts to build a hydrofoil, in the process of which despite failing to do so he still ends up with an entertaining airboat to play around in.

What is interesting from our point of view is his opting for electrical motors and aero-propellers in lieu of water-screws. The reason why is not far displaced either: there is a plethora of electrical motors designed for airscrews to choose from, against a dearth of options when it comes to same with water-screws. This beside the clear advantage of boats that can (a) ride over tarmac and then (b) hover over to the water.

My biggest fear going forward is that the prototype may not be nearly so fast as we'd hope. Although absent the payload here, and the prospects for it being so look better. The motors to my mind look to be on a par with T-motor's U13, and tho' they produce five times the thrust of the U7, we've nowhere near the gross weight appearing here.

On water as in air, lightness is a virtual circle... lighter gross weights requiring lighter motors that require lighter batteries and a structure that need not be so substantial: all of which means less cash is required to return similar speeds.

Undue weight in air or on water, however, kills off projects and occasionally people.