Lighter than air...

I have a radio controlled blimp that a friend gave me while I was
recovering from surgery. It's been a blast to play with.

Filled it back up with He a couple of weeks ago and parked it on
the ceiling at home. (without the drive unit)

It has deflated slowly. At first it was slammed hard against the
ceiling, but as time passes, it settled tail down a bit, then more
until it hung vertically.

Last night it started wandering around the house all by itself.

This morning it was floating along the living room about 3 feet off
of the floor. As it came into the "computer room" where the temp is
several degrees cooler, it settled down to about 1 foot and nosed
around checking everything out.

Then it turned around and floated back into the living room - and
rose back up to near 3 feet again!

While I understand the principles involved (temperature/pressure), I've
never seen such a clear demonstration of them.

Fascinating....

Richard

"Morgans" wrote in message
...

"Richard Lamb" wrote

Then it turned around and floated back into the living room - and
rose back up to near 3 feet again!

While I understand the principles involved (temperature/pressure), I've
never seen such a clear demonstration of them.

Fascinating....

As kids, my brother and I would get a helium balloon, and make a gondola
out
of a cut down paper cup. We would then add and subtract ballast, in the
form of tiny torn-up scraps of paper, to fine tune the hover. We could
get
it to hover at about 5 feet, and it would follow the air currents around
the
house. Tons (and hours) of fun!
--
Jim in NC

I was manning a booth at a trade show when a competitor launched a few
hundred He balloons with his company logo on them. He had weighed them off
to neutral bouancy before release so they would wander the hall at constant
altitude - hopefully eye level .

Unfortunately, most of them wound up blocking air return grates overheating
the event center's AC system. I understand that was an expensive show for
the vendor.

Bill Daniels

Bill Daniels wrote:


I was manning a booth at a trade show when a competitor launched a few
hundred He balloons with his company logo on them. He had weighed them off
to neutral bouancy before release so they would wander the hall at constant
altitude - hopefully eye level .

Unfortunately, most of them wound up blocking air return grates overheating
the event center's AC system. I understand that was an expensive show for
the vendor.

Bill Daniels

Looks like maybe he should have gone with the RC models and had as an
attraction at his booth that you got to take the controls. Add to that
a battery powered RF video camera on the RC blimps, with the monitors
at the booth, and you'd be sure to draw a crowd.

Don W.

"Richard Lamb" wrote

Then it turned around and floated back into the living room - and
rose back up to near 3 feet again!

While I understand the principles involved (temperature/pressure), I've
never seen such a clear demonstration of them.

Fascinating....

As kids, my brother and I would get a helium balloon, and make a gondola out
of a cut down paper cup. We would then add and subtract ballast, in the
form of tiny torn-up scraps of paper, to fine tune the hover. We could get
it to hover at about 5 feet, and it would follow the air currents around the
house. Tons (and hours) of fun!
--
Jim in NC

This was one of those beautiful spring like days.
About 72 F high. I turned the heat on about sundown as it was starting
to chill a bit.

Ok, I thought, here is a chance to observe and maybe learn how the lift
fairies work (feathers, we don' need no stinkin' feathers!)

My little floating friend got real excited. Actually went right up and
kissed one of the air vents in the ceiling! (Hey, I didn't know he was
THAT kind of blimp!)

Within a couple of minutes he settled down on the floor over in one
corner, and - went to sleep, I think. Hasn't moved an inch since then.

That first reaction was so strange though.
Temperature? Or was it pressure?
Or was it air flow past one side?

Air is sure strange stuff...

Richard

Richard Lamb wrote:

Air is sure strange stuff...

One of my favorite physics lesson is what happens when you have a
helium baloon floating in the back of your car.

Hit the gas, it flies forward.

Stomp the brakes, it flies to the back.

Or more accurately, the air in the car does the opposite.

Mark "light is relative" Hickey

Mark Hickey wrote:

Richard Lamb wrote:


Air is sure strange stuff...


One of my favorite physics lesson is what happens when you have a
helium baloon floating in the back of your car.

Hit the gas, it flies forward.

Stomp the brakes, it flies to the back.

Or more accurately, the air in the car does the opposite.

Mark "light is relative" Hickey

Neat!

I've been thinking about that pervious odd behavior of the blimp.

Try this on for size?

The air coming out of the vent hits the floor and spreads out.

Being warmer than the air around it, it starts to rise.

The stream blowing from the vent causes a lower pressure area
around it, causing the air rising from the floor to move back
in toward the stream.

That's a basic convection circulation system.
So the dumb blimp wanders over toward the down flow coming from above.

The lower pressure around the stream is what caused the blimp to stick
to the down flow. (it never did go completely into the stream.
Just stuck to the side of it.)

Now the air in the flow is warmer than the air in the room, and the
blimp's helium temperature is still at the lower room temp.

But the He warms quickly, expanding the bag a bit, and causing the
blimp to defy not only gravity - but the direction of the stream,
and rise up to the very attractive vent.

THEN, as the temperature in the room increased, and matched the temperature
of the blimp, the silly sated think sank back to the floor.


Anybody buy into that?
Or is this as demented as that TRUTH guy???

Richard

Naw, ya'll got it all wrong.

Feathers aren't magical - just pretty.
Well, MOST of them are.
Ostrich feathers aren't so cute though.

Which explains why they can't fly.
The Lift Fairies don't care much for ugly.
(read the NASA report more carefully!)

MY experiments show that Lift Fairies just love helium!
It's light and fluffy, and tickles their noses.

HeHeHe!

Richard

"Richard Lamb" wrote in message
news
MY experiments show that Lift Fairies just love helium!
It's light and fluffy, and tickles their noses.

HeHeHe!

Richard

Don't understand how feathers enter into the question of lift. I've seen
references to both
lift demons and lift fairies and neither have feathers. Demons wings are
leather sails like
those of pterasaurs or bats and fairy wings are like those of dragonflies.
That should lay to rest the obviously false theory of feathery antigravity
forces. Now helium dependent lift fairys, hmmmm, or even hydrogen generating
lift demons, well, that raises some intersting possubilities. No, no, I
don't think so, it totally confuses the lighter than air craft and the
heavier than air craft hierarchies. its just too confusing.(snG)

Harold
KD5SAK

In article . net,
Richard Lamb wrote:

I have a radio controlled blimp that a friend gave me while I was
recovering from surgery. It's been a blast to play with.


This was posted on the soaring newsgroup a while back. It is relevant to
the lighter than air (house blimps thread).




*****

Last week while travelling I stopped at a Zany Brainy
store and saw that they had a blimp for sale. It's called
Airship Earth, and it's a great big balloon with a map of
the Earth on it, and two propellors hanging from the
bottom. You blow up the balloon with helium put batteries
in it, and you have a radio controll indoor blimp.

I'd seen these things for sale in Sharper Image catalogs
for $60-$75. At Zany Brainy it was on clearance for $15.
What a deal!

Last night my wife was playing tennis and it was just my
daughter and I at home. I bought a small helium tank from
a party store, and last night we put the blimp together.
Let me tell you, it's quite a blimp. It's huge. The
balloon has like a 3 ft diameter. We blew it up with the
tank attacched the gondola with the propellors, and put in
batteries. Then we balanced the blimp for neutral bouyancy
with this putty that came with it, so it hangs in the air
by itself neither rising nor falling. It was easy and fun,
and then I blew up another balloon and made Mickey Mouse
helium voices for my daughter.

My three year old girl loved it. We flew the blimp all
over the house, terrorized the dog, attacked the fish
tank, and the controls were so easy my daughter could fly.
Let's face it, blimps are fun.

Alas, the fun had to end and my daughter had to go to
sleep. I left the blimp floating in my office downstairs,
my wife came home, and we went to bed, and slept the sleep
of the righteous.

At this point it is important to know that my house has
central heating. I have it configured to blow hot air out
on the ground floor and take it in at the second floor to
take advantage of the fact that heat rises.

The blimp which was up until this moment a fun toy here
embarked on a career of evil. Using the artificial
convection of my central heating, the blimp stealthily
departed my office. It moved silently through the living
and drifted to the staircase. Gliding wraithlike over the
staircase it then entered the bedroom where my wife and I
lay sleeping peacefully.

Running silently, and gliding six feet or so above the
ground on invisible and tiny air currects it approached
the bed. In spite of it's noiseless passage, or perhaps
because of it, I awoke. That doesn't really say it
properly. Let me try again.

I awoke, the way you awake at 2:00 AM when your sleeping
senses suddenly tell you without reason that the forces of
evil on converging on you. That still doesn't do it. Let
me try one more time.

I awoke the way you awake when you suddenly know that
there is a large levitating sinister presence hovering
towards you with menacing intent through the maligant
darkness.

Now sometimes I do wake up in the middle of the night
thinking that there are large sinister and menacing things
floating out of the darkness to do me and mine evil.
Usually I open my eyes, look and listen carefully, decide
it was a false alarm, and go back to sleep.

So, the fact that I awoke in such a manner was not all
that unusual.

On this occasion I awoke to the sense that there was a
large menacing presence approaching me silently out of the
gloom, so I opened my eyes, and there it was! A LARGE
SILENT MENACING PRESENCE WAS APPROACHING ME OUT OF THE
GLOOM, AND IT COULD FLY!!!

Somewhere in the control room of my mind a fat little
dwarf in a security outfit was paging through a Penthouse
while smoking a cigar with his feet up on the table,
watching the security monitors of my brain with his
peripheral vision. Suddenly he saw the LARGE SILENT
SINSITER MENACING FLOATING PRESENCE coming at me, and he
pulled every panic switch and hit every alarm that my body
has. A full decade's allotment of adrenaline was dumped
into my bloodstream all at once. My metabolism went from
"restful sleep mode" to HOLY ****! FIGHT FOR YOUR LIFE OR
DIE!!!! mode" in a nanosecond. My heart went from twenty
something beats per minute to about 240 even faster.

I always knew this was going to happen. I always knew that
skepticism and science were mere psychological decorations
and vanities. Deep in our alligator brains we all know
that the world is just chock full of evil and monsters and
sinister forces aligned against us, and it is only a
matter of time until they show up. Evolution know this,
too. It knows what to do when the silent terror comes at
you from out of the dark.

When 50 million years worth of evolutionary survival
instinct hits you all at once flat in the gut at 200 mph
it is not a pleasant sensation.

Without volition I screamed my battle cry (which is
indistinguishable to the sound a little girl makes when
you drop a spider down her dress (not that I'd know what
that sounds like,) and lept out of bed in my underwear.

I struck the approaching menace with all my strength and
almost fell over at the total lack of resistance that a
helium balloon offers when you punch the living **** out
of it with all the stength that sudden middle of the night
terror produces.

It's trajectory took it straight into the ceiling fan
which whipped it about the room at terrifying velocity.

Seeking a weapon, I ripped the alarm clock out of its plug
and hurled it at the now High Velocity Menacing presence
(breaking the clock and putting a nice hole in the wall.)

Somehow at this moment I suddenly realized that I was
fighting the blimp, and not a monster. It might have been
funny if I didn't truly and actually feel like I was
having a legitimate heart-attack.

On quivering legs I went to the bathroom and literally
gagged into the toilet while shaking uncontrollably with
the shock of the reaction I'd had.

Unbeleivably, both my wife and daughter had completely
slept through the incident. When I decided that I wasn't
having a heart attack after all I went back into the
bedroom and found the blimp which had somehow survived the
incident.

I took it to the walk in closet and released it inside
where it floated around with the air currents released
from the vents in there. I closed the door, this sealing
it in, and went back to bed. About 500 years later I fell
asleep.

***

At about 7 am my wife awoke. She had been playing tennis
and wasn't aware that we have assembled the blimp the
previous evening, and that is was now floating around the
the walk-in closet that she approached.

The dyndamic between the existing air currents of the
closet and the suction caused by opening the door was just
enough to give the blimp the appearance of an Evil
Sinister Menace flying straight towards her.

This time the blimp did not survive the encounter, nor
almost, did I, as I had to explain to my very angry spouse
what motivated me to hide an evil lurking presence in the
closet for her to find at 7 am.

I can order replacement balloons on the internet but I
don't think I will.

Some blimps are better off dead.