Homebuilt Helo #41

As a part of that 'base camp' review I decide to ditch the fascias round the uppermost part of the booth. We lose the logo, but this can be transferred to a dome up top that will cover the avionics like a hood.

At the same time there was always the choice as to whether to build the drone apart from the accommodation, but at this stage and possibly into the future the latter may form the basis of the co-rotating octocopter from which the passenger is suspended.

I've taken a side of the original four-pronged drone to use as a means of capping the space-frame, and at the same time transferred the expanded foam sheet to pack out the roof-space.

Principally this aims at damping vibrations from being passed to the flight controller and being interpreted as instant trajectories of the airframe instead of the transient fluctuations they are.

As the NTSB found after Boeing's own personal air vehicle prototype fell from the sky:

The June 4 crash of Boeing's urban air mobility prototype occurred after resonant aircraft vibrations incorrectly activated the vehicle's ground mode, commanding the motors to shut down.

After the incident the manufacturer abandoned development as I recall, and we don't want to give up that easily do we?

Homebuilt Helo #40

It's worth at every stage of prototyping stepping back to review progress and consider if at all it would be worth proceeding... a consideration from within base camp. James Dyson is the UK's most successful contemporary industrialist and in the time he took developing his vacuum cleaner, his son developed from toddler to seventeen year old.

It pays also to identify a marketing niche, and I think this has to be along a DIY route. The kit-built helicopter market has a spotted history, which is unsurprising given the fact that the conventional helicopter is relatively complex, and has to be got right. It is also probably true that like most kit aeroplanes, kit helicopters are rarely completed if only because they are pre-deceased by their owners.

On the other hand the world's most successful helicopter is probably the R22, which was sold ex-factory from the get-go and an examination of its pricing (according to its wiki page) is worthwhile. Pitched at around $18,000 by Frank Robinson at the outset it would eventually retail for nearly double in 1979, and still does so today at $375,000. In other words it sold for around double what he thought it would and continues to do so even nowadays, albeit it at a cost around twenty times beyond expectation.

It does suggest that eVTOLs designed admittedly for a single operator in place of two may in the long term present a viable business opportunity, but most likely in ARTF or 'almost ready to fly' format. This is a halfway house that broadly satisfies regulators as well as insurers and owners, in that it represents a proven product that unlike the run of kits is likely to see daylight.

It will likely to become easier with the passage of time to build airframes like the one in the picture: in the way that personal computing devices started out as a kit of parts that had to be assembled by its owner unlike shiny smartphones that appear from out of a box. And in the long run people will simply build and fly them for fun if the price point is right, in the way that both cars and aircraft developed from their beginnings.

Most electrical scooters in the world (like cars) are operated illegally, in the way most people watch soccer matches on TV illegally. The focus of product development is not so much to outlaw what people would like to do in their own back yard so much as to make sure they don't kill themselves doing it.

We've still retrospective adjustments to make to our people-carrying drone in coming days, so hang on in there.

Homebuilt Helo #39

Frankly I'm going to take a break now until the world provides the 3 x 30mm bolts that I feel it owes me...

Homebuilt Helo #38

And now I know why these were 3D-printed by the poor bastard who had to fit these motors to the last prototype, for they raise the spindle clear of the airframe.

Another of the joys of working with the U7 motor is that it uses shitty little 3mm bolts to fix it in place, for which ideally I need bolts of 30mm length that UK DIY depots do not generally stock.

There will therefore be an interlude whilst I reduce sixteen 40mm bolts from the local hardware store to a 30mm shank using an angle-grinder.

An exercise that will convince you ~ if nothing else does ~ of the futility of life.

Homebuilt Helo #37

Here's the base of the U7 motor, from where we can see that the spindle to which the rotor is attached (the cylinder or 'out-runner' at left which does the turning) extends beyond the fixed base... guaranteeing that as you tighten the motor in place, it acts as a brake preventing the motor from operating.

Larger motors from the same company do not include this feature, and I guess at the quarterly sales meets that there's a bonus for shifting the stock on the unsuspecting.

A suitable rename of the U7 as a part of this effort might perhaps be the FU7.

Why am I doing this?

Homebuilt Helo #36

I devote the next three posts to T-motor's U7 V2 that I'm using here, and which can best be described as 'useless'.

Blow the pic up and you'll see how the bolt-holes perfectly align with that black wire which powers the motor, to the extent that you short-circuit it should those bolts go just a little too far. Had they pitched holes at 35mm instead of 30mm you'd be home clear, but where's the fun in that?

This incidentally is the improved 'V2' version of the motor... those with the V1 version are advised to slit their wrists at this stage.

Homebuilt Helo #35

Here's a bird's eye view, or at least to the extent any bird would want to be garaged.

The ends of each undercarriage leg include a length of threaded rod glued in place so as to support a threaded door-knob.

This means that should there be any movement during touchdown, the undercarriage has less chance of snagging the surface.