Light Electric Rotorcraft

[[email protected]]

Hi,

I was looking at pictures of Yamaha's recently announced Deinonychus
motorbike, and was struck by how functional and light it looked, due to
having been designed around electric wheel-motors:

http://www.gizmag.com/go/4686/

Somehow this same barebones functional look reminded me a bit of the
Mosquito helicopter, also featured on the same site:

http://www.gizmag.com/go/4628/

And so it made me wonder whether some of the same elements used to make
the Deinonychus motorbike couldn't be rearranged to make a light
electric-powered mini-helicopter.

Ugh, here's my ascii-art pic ;P

--------=======-------
|
|
|
|
||
||
_||____
| \
__ /
/ \
| |
\__/

So the top part is the rotor and the = signs are the wheel motor that
turns it.
Then you have the shaft with the seat coming off near the bottom of it.
And the circular shape at the bottom is supposed to be a tire for
landing gear, meant to take the main shock of landing, but the pilot's
legs are supposed to provide lateral stability on landing and takeoff.
Some Segway-style control logic on the bottom wheelmotor could be used
to provide stability on the forward-backward axis during
landing/takeoff. This would include allowing the swivel-arm, on which
the bottom tire is mounted, to move and change its angle.

So the tire underneath is supposed to have fan-blades as the spokes,
and is spun by its wheelmotor to provide the counter-rotative thrust
like a tail-rotor. After takeoff, the swivel arm slowly swivels the
tire back and up to position it at the rear. Likewise, during landing
approach it swivels down and forward to serve as the Segway-style
landing gear.

While landing, the wheelmotors will use regenerative braking to stop
the rotors as quickly as possible.

What do you think? Comments, critiques, suggestions?

[Orval Fairbairn]

In article . com>,
wrote:

> Hi,
>
> I was looking at pictures of Yamaha's recently announced Deinonychus
> motorbike, and was struck by how functional and light it looked, due to
> having been designed around electric wheel-motors:
>
> http://www.gizmag.com/go/4686/
>
> Somehow this same barebones functional look reminded me a bit of the
> Mosquito helicopter, also featured on the same site:
>
> http://www.gizmag.com/go/4628/
>
> And so it made me wonder whether some of the same elements used to make
> the Deinonychus motorbike couldn't be rearranged to make a light
> electric-powered mini-helicopter.
>
> Ugh, here's my ascii-art pic ;P
>
> --------=======-------
> |
> |
> |
> |
> ||
> ||
> _||____
> | \
> __ /
> / \
> | |
> \__/
>
> So the top part is the rotor and the = signs are the wheel motor that
> turns it.
> Then you have the shaft with the seat coming off near the bottom of it.
> And the circular shape at the bottom is supposed to be a tire for
> landing gear, meant to take the main shock of landing, but the pilot's
> legs are supposed to provide lateral stability on landing and takeoff.
> Some Segway-style control logic on the bottom wheelmotor could be used
> to provide stability on the forward-backward axis during
> landing/takeoff. This would include allowing the swivel-arm, on which
> the bottom tire is mounted, to move and change its angle.
>
> So the tire underneath is supposed to have fan-blades as the spokes,
> and is spun by its wheelmotor to provide the counter-rotative thrust
> like a tail-rotor. After takeoff, the swivel arm slowly swivels the
> tire back and up to position it at the rear. Likewise, during landing
> approach it swivels down and forward to serve as the Segway-style
> landing gear.
>
> While landing, the wheelmotors will use regenerative braking to stop
> the rotors as quickly as possible.
>
> What do you think? Comments, critiques, suggestions?


Of course, they can! All you will need is a really LONG extension cord!

[Montblack]

("Morgans" wrote)
> My bet is that the batteries will weigh too much, and be too expensive.
>
> I HATE being a pessimist!


Diesel turning a generator?


Montblack

[Morgans]

> wrote

> Somehow this same barebones functional look reminded me a bit of the
> Mosquito helicopter, also featured on the same site:
>
I didn't see what the engine was on the heli, but if you know what it is, do
some calculations. Figure the wattage for the gas engine heli, then convert
it into amp hours for the length of time that you want to fly, then figure
out how much weight of batteries you will have to carry.

My bet is that the batteries will weigh too much, and be too expensive.

I HATE being a pessimist!
--
Jim in NC

[Morgans]

"Montblack" > wrote

> Diesel turning a generator?

And this is supposed to be saving weight? <g>

Why not just turn the rotor with the diesel? Too obvious?
--
Jim in NC

[[email protected]]

Morgans wrote:
> > wrote
>

<SNIP>

>
> I HATE being a pessimist!
> --
> Jim in NC

Then stop. It's a simple 12 step program... :-)

-Matt

[red]

manofsan,
That's an interesting idea. Now put another lifting rotor on top of the
main shaft, counter-rotating, and you can forget the tail rotor, with all
of its' complexities. Use spider gears idling between the rotors, so both
rotors will turn at equal rates, even if one motor fails.
Pivot the entire rotorhead like a Benson autogyro, and control that with a
joystick. Steer it with a large rudder behind the pilot that can tilt (for
yaw axis control in hovering flight) *and* swing left-and-right (for
directional control in forward flight). You could do that very simply,
with a rudder hinge line angled 45 degrees back from the main rotor shaft,
and rudder cables that pull the lower end of the rudder directly.
The flight control system at the pilot's position could be identical to an
autogyro. You would need rudder pedals, throttle, and joystick only.
There would be no cyclic controls, no collective pitch controls, and no
tail rotor controls (because there is no tail rotor). This is *much* less
machinery than the AirScooter:
http://www.gizmag.com/go/3056/
Feed it with fuel cells (aviation ain't cheap).
Watch out for birds... Don't forget the BRS :-)
http://brsparachutes.com

My ASCII art:
____
| |
|BRS |
\ /
counter-rotating ||
-------------------(motor)--------------------
lift rotors *||* <--spider gears
-------------------(motor)--------------------
______||-----\
_____/h\.....|| \ autogyro
( i\....||\ \<--joystick
( n\...|| \ \
(rudder g\..|| \seat pedals
(__________e\.|| \______ /
/----------------------------/--\
/ main frame w/fuel cells \
/-----------------------------------\
o O
--
(Replies *will* bounce, unless you delete
the letter A from my email address)
Cheers,
Red

wrote:
> I was looking at pictures of Yamaha's recently announced Deinonychus
> motorbike, and was struck by how functional and light it looked, due to
> having been designed around electric wheel-motors:
> http://www.gizmag.com/go/4686/
> Somehow this same barebones functional look reminded me a bit of the
> Mosquito helicopter, also featured on the same site:
> http://www.gizmag.com/go/4628/
> And so it made me wonder whether some of the same elements used to make
> the Deinonychus motorbike couldn't be rearranged to make a light
> electric-powered mini-helicopter.
>
> Ugh, here's my ascii-art pic ;P
>
> --------=======-------
> |
> |
> |
> |
> ||
> ||
> _||____
> | \
> __ /
> / \
> | |
> \__/
>
> So the top part is the rotor and the = signs are the wheel motor that
> turns it.
> Then you have the shaft with the seat coming off near the bottom of it.
> And the circular shape at the bottom is supposed to be a tire for
> landing gear, meant to take the main shock of landing, but the pilot's
> legs are supposed to provide lateral stability on landing and takeoff.
> Some Segway-style control logic on the bottom wheelmotor could be used
> to provide stability on the forward-backward axis during
> landing/takeoff. This would include allowing the swivel-arm, on which
> the bottom tire is mounted, to move and change its angle.
>
> So the tire underneath is supposed to have fan-blades as the spokes,
> and is spun by its wheelmotor to provide the counter-rotative thrust
> like a tail-rotor. After takeoff, the swivel arm slowly swivels the
> tire back and up to position it at the rear. Likewise, during landing
> approach it swivels down and forward to serve as the Segway-style
> landing gear.
>
> While landing, the wheelmotors will use regenerative braking to stop
> the rotors as quickly as possible.
>
> What do you think? Comments, critiques, suggestions?

[Frank van der Hulst]

Morgans wrote:
> "Montblack" > wrote
>
>
>>Diesel turning a generator?
>
>
> And this is supposed to be saving weight? <g>
>
> Why not just turn the rotor with the diesel? Too obvious?

It *might* be possible that diesel-electric system would be lighter than
pure electric or pure diesel.

A small diesel could be optimised to run continuously at its most
economical RPM, producing only a little more electricity than needed to
drive the rotor in level flight. For additional power, electricity from
the battery would also drive the rotor. When descending, the battery
gets charged faster.

[[email protected]]

Hi red, thanks for the great ideas. :)

Hmm, I read about how a coax design can use differential rotation speed
between the 2 rotors for the purpose of turning the aircraft. That'd be
pretty easy to do with a wheelmotor for each rotor.

Here's a link to a new kind of wheelmotor which is attracting
attention:

http://www.wavecrestlabs.com

The company is headed by General Wesley Clark, former NATO commander.
Regarding portable fuel cell for propulsion, here's another link:

http://www.intelligent-energy.com/index_article.asp?secID=15&secondlevel=796&artID=3709

And hydrogen is a lightweight fuel too, for lower fuel load.
But suppose you want some extra juice sometimes, for more
maneuvering/lifting power. Then use the new Toshiba battery:

http://www.dpreview.com/news/0503/05032903tosh1minbatt.asp

It can apparently discharge and absorb energy at a very high rate. This
might be useful for using regenerative braking to recover energy from
your rotor when you're reducing airspeed/altitude, since a wheelmotor
can convert torque/rpm back into electricity. Once you've landed,
regenerative braking would allow you to quickly bring the rotors to a
stop while recovering energy from them.

I'd also imagine the electric motors would be quieter too, so your
eardrums don't take a beating.

[Frank van der Hulst]

wrote:
> And hydrogen is a lightweight fuel too, for lower fuel load.
> But suppose you want some extra juice sometimes, for more
> maneuvering/lifting power.

Hydrogen is only a lightweight fuel in its uncompressed, gaseous form.
In fact, in terms of energy per Kg, hydrogen is not a good fuel. Storing
hydrogen in sufficient density to be useful requires strong (read heavy)
tanks.

[[email protected]]

Well, some research group is claiming to have come up with a new way to
store hydrogen, which may make it more feasible as a vehicular fuel:

http://www.sciencedaily.com/releases/2005/09/050907102549.htm

http://denmark.dk/portal/page?_pageid=374,862918&_dad=portal&_schema=PORTAL

http://www.amminex.com/

http://www.thewatt.com/modules.php?name=News&file=article&sid=763

http://www.investindk.com/visNyhed.asp?artikelID=13670

But admittedly, it's very new and as yet untried in the marketplace.

[Frank van der Hulst]

Richard Riley wrote:
> On Mon, 03 Oct 2005 10:52:49 +1300, Frank van der Hulst
> > wrote:
>
> wrote:
> :> And hydrogen is a lightweight fuel too, for lower fuel load.
> :> But suppose you want some extra juice sometimes, for more
> :> maneuvering/lifting power.
> :
> :Hydrogen is only a lightweight fuel in its uncompressed, gaseous form.
> :In fact, in terms of energy per Kg, hydrogen is not a good fuel. Storing
> :hydrogen in sufficient density to be useful requires strong (read heavy)
> :tanks.
>
> Liquid hydrogen has the most energy per pound of any chemical fuel.
> It has 39,000 Wh/kg, gasoline only has 12,200 Wh/kg.
>
> Unfortunately it is also not very dense - even in it's liquid form.
> Liquid hydrogen has a density of 0.07 grams per cubic centimeter,
> whereas water has a density of 1.0 g/cc and gasoline about 0.75 g/cc.

Oops, yes, you're right. It was in terms of energy/volume that hydrogen
is poor, NOT energy/mass.

Therefore the container to hold your liquid hydrogen needs to be large.
It also needs to be strong, and therefore heavy.

Therefore, as Richard said, hydrogen won't be a practical aircraft fuel
unless the storage issue can be solved.

[Morgans]

"Frank van der Hulst" > wrote

> It *might* be possible that diesel-electric system would be lighter than
> pure electric or pure diesel.

I'm from Oklahoma. Show me!

> A small diesel could be optimised to run continuously at its most
> economical RPM,

It would already have to have a gearbox for a heli, so it can run whatever
RPM you want. An electric motor would also have a gearbox. Yes I know,
there are low speed electric motors, but they are huge and heavy.

> producing only a little more electricity than needed to
> drive the rotor in level flight.

There will always be losses, driving a generator, then a motor. You will
have to have at least 10% more power output by the diesel motor, just to
break even, and more than that to charge batteries.

So lets see, we have to have a gearbox both ways, no change in weight
between the two. We will have to have a bigger diesel to take care of
losses, so penalty goes to electric. We would have to have batteries for
electric, so more penalty for electric. Since our electric has gotten
heavier, we will have to have a bigger engine, and more fuel, so BIG penalty
for electric.

> For additional power, electricity from the battery would also drive the
rotor. When >descending, the battery gets charged faster.

What you are talking about is like an autorotation. The blades in an
autorotation have to go to negative pitch, just to make the blades maintain
RPM, and to get more power to generate electricity than a plain
autorotation, they would have to be at even more negative pitch. You would
have to descend so fast to get the rotor to produce electricity, your
passengers would freak!
--
Jim in NC

[Frank van der Hulst]

Morgans wrote:
> "Frank van der Hulst" > wrote
>>A small diesel could be optimised to run continuously at its most
>>economical RPM,
>
>
> It would already have to have a gearbox for a heli, so it can run whatever
> RPM you want. An electric motor would also have a gearbox. Yes I know,
> there are low speed electric motors, but they are huge and heavy.

The whole point of these wheelmotors is that they are smaller than
equivalent DC motors, and turn at low speeds. The numbers I've seen are
110-150rpm. See http://www.smartmotor.no/products/quiet_traction/ --
this talks about wheelmotors in relation to wheelchairs, and claims
twice the efficiency over traditional DC+gearbox systems.

You could think of the generator/motor combination as an electrical
rather than mechanical gearbox.

Another interesting site is http://www.killacycle.com/ -- an
electrically powered drag bike that gets 9.450 seconds @152.07 mph over
the 1/4 mile. Still a long way from the 5.895 @ 238.22 nitro powered
world record though.

>>producing only a little more electricity than needed to
>>drive the rotor in level flight.
>
>
> There will always be losses, driving a generator, then a motor. You will
> have to have at least 10% more power output by the diesel motor, just to
> break even, and more than that to charge batteries.
>
> So lets see, we have to have a gearbox both ways, no change in weight
> between the two. We will have to have a bigger diesel to take care of
> losses, so penalty goes to electric. We would have to have batteries for
> electric, so more penalty for electric. Since our electric has gotten
> heavier, we will have to have a bigger engine, and more fuel, so BIG penalty
> for electric.

But the diesel only ever runs at one speed... it's most economical. I'm
assuming that there will be significant weight savings in that. I may be
wrong in that assumption.

I do know that having a car petrol engine which can potentially deliver
a lot more horsepower means that it uses more fuel at lower horsepower
output. Maybe this relationship doesn't apply to diesels.

>>For additional power, electricity from the battery would also drive the
>
> rotor. When >descending, the battery gets charged faster.
>
> What you are talking about is like an autorotation.

No. I'm saying that when descending, less power from the
engine/generator goes to the rotor, leaving more to go to the battery.

[red]

manofsan,
Differential rotor speeds -will- rotate the aircraft, but will that turn
the aircraft, in level flight, or just rotate the aircraft in yaw? The
hard part about differential rotor speeds is not in yawing the aircraft.
The hard part is NOT yawing the aircraft, constantly. Gyros might do the
job of balancing rotor speeds for you (with *more* expense and complexity),
but you would still lose the safety advantages of simplicity, and
maintaining control if one motor fails. The spider gears and one motor
might not maintain altitude, but you could still move forward and steer as
you descend slowly, to select a good place for the BRS deployment. In a
deployment situation, one motor could still be used for a last-minute burst
of power, to soften the parachute landing.
Recovering energy by auto-rotation would mean a lot of weight and
complexity for very small gains. Aircraft are like boats, always fighting
drag, and if aircraft could get anything back on descent, they would have
to expend a lot more energy to do the climb, first. You can never win
against drag, so at best, we just try to cut our losses, up front.
I hear Boeing is working on a single-engine plane using a fuel cell and an
electric motor to provide propellor thrust, so that technology seems
realistic. New hydrogen storage systems can derive their hydrogen "fuel"
from other liquids, rather than highly pressurized hydrogen gas, which
would need strong and heavy tanks.
The WaveCrest motor idea looks good, too.
--
(Replies *will* bounce, unless you delete
the letter A from my email address)
Cheers,
Red

wrote:
>
> Hi red, thanks for the great ideas. :)
>
> Hmm, I read about how a coax design can use differential rotation speed
> between the 2 rotors for the purpose of turning the aircraft. That'd be
> pretty easy to do with a wheelmotor for each rotor.
>
> Here's a link to a new kind of wheelmotor which is attracting
> attention:
>
> http://www.wavecrestlabs.com
>
> The company is headed by General Wesley Clark, former NATO commander.
> Regarding portable fuel cell for propulsion, here's another link:
>
> http://www.intelligent-energy.com/index_article.asp?secID=15&secondlevel=796&artID=3709
>
> And hydrogen is a lightweight fuel too, for lower fuel load.
> But suppose you want some extra juice sometimes, for more
> maneuvering/lifting power. Then use the new Toshiba battery:
>
> http://www.dpreview.com/news/0503/05032903tosh1minbatt.asp
>
> It can apparently discharge and absorb energy at a very high rate. This
> might be useful for using regenerative braking to recover energy from
> your rotor when you're reducing airspeed/altitude, since a wheelmotor
> can convert torque/rpm back into electricity. Once you've landed,
> regenerative braking would allow you to quickly bring the rotors to a
> stop while recovering energy from them.
>
> I'd also imagine the electric motors would be quieter too, so your
> eardrums don't take a beating.

[Flyingmonk]

Richard Riley wrote:
>So you build your aircraft engine so it's best fuel economy is at full
>throttle. If it's not getting it's best economy during decent and
>landing, that's fine, it's at idle anyway.

You must be thinking of fixed-wings Richard. A helo's engine only goes
to idle during and auto not during decent nor landing. Actually during
landing a helo uses a whole lot of power, more than while flying (due
to loss of translational lift).

Bryan "The Monk" Chaisone

[[email protected]]

Richard Riley wrote:

>
> Believe me, I've been doing the trade studies for the last 3 years.
> You can't buy a COTS fuel cell, and the volume required to store H2
> (not to mention the handling difficulties) mean it won't be used as a
> fuel for anything but very high end, special purpose machines for a
> very long time to come.

How does liquified methane (at high pressure, ambient temperature) look
to power a conventional internal combustion engine, or perhaps even a
methane fuel cell?

I think that methane requires somewhere around 3700 psi to compress it
into a liquid at normal temperature, surely there's got to be some
carbon-fibre reinforced, aluminum polyester-lined composite tank
technology available nowadays that can handle the pressures necessary
to handle non-cryo liquified methane, without being prohibitively heavy
for an aircraft. Methane has a motor octane rating of around 130 in a
piston engine too, and you certainly won't be needing a fuel pump, just
a good strong pressure regulator / phase change heat
exchanger/gassifier at the tank's output valve to feed a direct fuel
injection metering system for the engine. You could probably employ the
phase change heat exchanger as a clever way to air-condition the cabin
too! (just make damn sure of no leaks)

[Flyingmonk]

Richard Riley wrote:
>What percentage of a helicopter's flying lifecycle is spent at or near
>it's rated power output, and what percentage is spent at a small
>fraction of that rated power output?

About 100% of the time Richard, more power to fly higher, less to fly
lower. It only goes into idle while NOT flying.

Bryan "The Monk" Chaisone

[[email protected]]

Here is yet another interesting design from that same website:

http://www.gizmag.com/go/3107/

I wonder if this could be converted into a gyroplane? Here's how I
imagine it.

sorry, my ascii art isn't good enough to reproduce the chassis, so I
just drew the tires (which of course have the electric wheelmotors in
them):


==========
|
|

( o----------------+ ========

|
|
===========

Note that the "o-------------+" is supposed to be the rotor mast folded
back along the longitudinal axis of the craft. Okay, I guess that would
require the craft to have some kind of upper fuselage canopy for the
mast to attach to. The "o" is the base of the mast which attaches to
the upper fuselage canopy, while the "+" is where the rotor head would
be.
But the rotor mast wouldn't have to be very long, since it doesn't need
much height for its rotors to clear the rest of the craft. The rotors
themselves would be bent forward in V-shape from the rotorhead, with
their tips clipped to the sides of the fuselage/chassis.

So the wheelmotors roll the craft along the ground until it picks up
lots of speed. Then the rotor mast pops upright, the rotors are freed
and start spinning overhead. The craft then takes off like a gyroplane,
and once airborn the front tires swivel to face frontwards to act as
fan-props:

||
||____
|| |
|| |


( + =======


|| |
||___|__
||
||


Heh, very James Bond-ish, huh? ;P

[Terry Spragg]

Frank van der Hulst wrote:

> wrote:
>
>> And hydrogen is a lightweight fuel too, for lower fuel load.
>> But suppose you want some extra juice sometimes, for more
>> maneuvering/lifting power.
>
>
> Hydrogen is only a lightweight fuel in its uncompressed, gaseous form.
> In fact, in terms of energy per Kg, hydrogen is not a good fuel. Storing
> hydrogen in sufficient density to be useful requires strong (read heavy)
> tanks.

Unless you are driving an anti-static engineered lifting body shaped
dirigible, in which case, compressing or decompressing a little of
the surplus fuel / bouyancy medium using a "bouyancy bladder" device
allows ascent and descent without actual fuel expenditure, except
that required to compress the gas when descending. Quite the
inverse of a normal flying vehicle, where energy is expended to ascend.

Has anybody analyzed that in terms of fuel efficincy?

Terry K

[Terry Spragg]

Richard Riley wrote:

> On 3 Oct 2005 10:06:32 -0700, wrote:
> :
> :How does liquified methane (at high pressure, ambient temperature) look
> :to power a conventional internal combustion engine, or perhaps even a
> :methane fuel cell?
>
> Basically, it looks about the same as gasoline. It does have lower
> emissions, so it does well where regulations force low emissions
> standards. In my area they use it for city busses. But for aircraft,
> I don't see much advantage. For a fuel cell it has to be reformed to
> H2 and C02, that means more equipment and more weight - but you'd have
> to do that with any hydrocarbon.
> :
> :I think that methane requires somewhere around 3700 psi to compress it
> :into a liquid at normal temperature, surely there's got to be some
> :carbon-fibre reinforced, aluminum polyester-lined composite tank
> :technology available nowadays that can handle the pressures necessary
> :to handle non-cryo liquified methane, without being prohibitively heavy
> :for an aircraft. Methane has a motor octane rating of around 130 in a
> :piston engine too, and you certainly won't be needing a fuel pump, just
> :a good strong pressure regulator / phase change heat
> :exchanger/gassifier at the tank's output valve to feed a direct fuel
> :injection metering system for the engine. You could probably employ the
> :phase change heat exchanger as a clever way to air-condition the cabin
> :too! (just make damn sure of no leaks)
>
> I'm just not seeing that you get much in exchange for the weight and
> cost of the high pressure tanks. Gasoline is pretty good stuff.

Yes, not bad, but not perfect. Reciprocating ic engines typically
are 25% efficient overall, thanks to mechanical losses and un used
heat thrown out with the exhaust.

If an electric motor is 75% efficient with hi frequency small coils
and can regenerate braking and if we could recombine O2 and H2 to
make water and electricity directly, along with maybe steam rocket
exhaust, you might see an improvement, especially with elecro motor
wheels rotors that are tailored for speed so they need not
transmissions. Their only weight is in the magnets, coils, and
switching controllers.

Magnetoheterodynamic generators are quite efficient, I hear. If we
could use one to drive 2electric contra rotors using motor
torque to set pitch, we might get somewhere.

I personally think a huge low pressure H2 fuel tank might provide
zero cost lift, so H2 might yet be more efficient than even our
wildest imaginings, so long as we use anti static plastic film tanks
and squeezable bouyancy bladders, like fish do.

Much is to come in the future.

[John Halpenny]

Terry Spragg wrote:

> Richard Riley wrote:
>

<snip>

> I personally think a huge low pressure H2 fuel tank might provide
> zero cost lift, so H2 might yet be more efficient than even our
> wildest imaginings, so long as we use anti static plastic film tanks
> and squeezable bouyancy bladders, like fish do.

I believe there was an attempt to use hydrogen fuel in a Zeppelin. The fuel
was free, since you have to vent hydrogen as you burn fuel anyway to keep from
going up. They found that hydrogen was a very poor fuel, and their 400 hp
diesel engines only produced 50 hp on hydrogen.

>
>
> Much is to come in the future.




--

John Halpenny

If you are what you eat...
I'd rather be a pig than a vegatable.