Engineering Explained:Why Tesla's Are Bad at Towing

[redpoint5]

I don't see the engine redundancy in that design, and in a fixed pitch fan, you've got to have redundancy. At least in a helicopter, you can autorotate if the engine goes out.

I also don't see why these aircraft are dependent on batteries getting better. We've already got jetfuel, so why not make these with conventional jet engines?

[aerohead]

I just posted the beginning of observations on the Model X tow testing,at bottom of #1 (permalink)

[freebeard]

Originally Posted by redpoint5

I don't see the engine redundancy in that design, and in a fixed pitch fan, you've got to have redundancy. At least in a helicopter, you can autorotate if the engine goes out.

I also don't see why these aircraft are dependent on batteries getting better. We've already got jetfuel, so why not make these with conventional jet engines?

THe current stat-of-the-art (Rolls Royce and Aston Martin) is an hybrid octocopter. Elon Musk is commited to pure electric, and like Fuller he's ahead of the curve. Just not as far.

At https://youtu.be/dnxKo18lETk?t=2101 the illustration shows the rear disk tilted but calls it out as a gyroscopic stabilizer. So possibly all three are gimballed. The illustration is no doubt speculative any way.

[redpoint5]

If a "wing" fan went out, there is nothing on that side of the center of gravity to make up for the loss of lift. Gimballing the other fans can't make up for no lift on that side of the craft. Likewise, those fans require counter-rotation with respect to each other to prevent the craft from yawing. Who knows how to counter the yaw from that tail fan?

I'd expect a design closer to the Osprey, since they've already worked out VTOL using rotors.

One advantage of electric motors over conventional engines is their performance is the same regardless of air density. They aren't starved for air at 100k ft like a conventional turbofan engine would be.

For short trips, I still see EV helicopters being more likely. Quieter, more efficient, and relatively safe in case of engine failure.



One last thought I had regarding electric planes is that in conventional ones, spoilers are deployed to waste excess speed while descending. With an electrically powered plane, you could use the props to regen back to the battery to recover energy from excess speed.

[freebeard]

I'd expect a design closer to the Osprey, since they've already worked out VTOL using rotors.

The Osprey uses cross shafts

How does the V-22 Osprey share engine power between its rotors
http://aviation.stackexchange.com/qu...5067/ddg#35074

It is possible to drive the two rotors of the V-22 Osprey from a single engine using a segmented driveshaft connecting both engine shafts via gearboxes:

Also, whole-aircraft parachute.

[redpoint5]

Just looked up the Osprey top speed. 350 MPH is not fast enough. Might as well fly a heli at that point.

Copy the F-35? It does mach 1.6

[freebeard]

Too much empennage. I think the gyroscopic steering needs a stinger tail like the Naboo N-1 starfighter

[Hersbird]

Originally Posted by freebeard

THe current stat-of-the-art (Rolls Royce and Aston Martin) is an hybrid octocopter. Elon Musk is commited to pure electric, and like Fuller he's ahead of the curve. Just not as far.

I think his SpaceX program will have trouble on pure electric.

[Hersbird]

Originally Posted by aerohead

I just posted the beginning of observations on the Model X tow testing,at bottom of #1 (permalink)

I hope the reality of towing the current crop of trailers with an EV does lead to some better trailers. There is a lot of things that could be done in manufacturing that really wouldn't add much to the cost or detract much from the function to improve a modern camper.

Just cleaning off the roof would be a start.

[teoman]

That is a very good way of looking at it.