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Old Mar 04, 2012, 06:32 AM
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Amazing !! A model cricri that takes offf,flies and lands that slow

http://www.youtube.com/watch?v=PKfYv...ature=youtu.be
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Old Mar 04, 2012, 08:10 AM
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Amazing!!! How big is that thing? Motors? Very nice job!
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Old Mar 04, 2012, 10:46 AM
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There is another video in the motor threads. Call me a skeptic, but I dont believe what I am seeing. IMO, either it is slowed way down or it's fake. There is no way that little amount of wing loading can fly that slow. With a lot of speed maybe, but I dont think the wing has the lift to fly that big of a model that slow. Here is the other one.

http://www.rcgroups.com/forums/showt...5#post20934230

After further discussion, I agree in the other post that it has to be filled with helium or some other lighter than air, inert, gas. That would explain the big fuse.
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Old Mar 04, 2012, 12:26 PM
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Byrdman;

lets say its slowed something i dont understand that in normal how can it fly in that small place ! If it flies normal speed and everything is normal its not possible ! it should fly slow that kind of big plane in this kind of small place isnt it ?
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Old Mar 04, 2012, 01:01 PM
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2.4 M Christen Eagle indoor (3 min 20 sec)


The Cri Cri probably has a much lighter wing loading since the Eagle is running a 6s pack.

Azarr
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Old Mar 04, 2012, 01:08 PM
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This is pretty slow for an 8ft span B-17, flown indoors.

Slow flight is all about weight, the lack of it.


8-Foot B-17 RC Model Indoors (2 min 48 sec)
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Old Mar 05, 2012, 03:26 PM
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"Helium"

the cri-cri's huge bubble canopy is actually a huge helium filled balloon and the rest of the fuselage my well have other helium balloons enclosed

so a very very lightly built model reduces its weight by half

a mix of differential throttle (its a twin) and there you you have it.. a very nice guided balloon!

simple

David
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Last edited by how much; Mar 05, 2012 at 03:27 PM. Reason: spelling error
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Old Mar 06, 2012, 11:16 AM
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Take a look at the bottom of the fuse. It is a lifting body like the space shuttle. The surface area is massive, possible greater than the wing. You can also see the tail section "wiggle" so it is built extremely light. Even if it was filled with helium, that volume is so small it would have little effect on the weight.
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Old Mar 06, 2012, 11:58 AM
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BTW, that thing looks like it is almost full scale. That plane is TINY in real life. I would say it is probably 80-90% scale.
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Old Mar 06, 2012, 05:21 PM
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[QUOTE=beerbrewer;20954928 Even if it was filled with helium, that volume is so small it would have little effect on the weight.[/QUOTE]


???????????????????

so run that by me again!

lets try a basic maths lesson....

you have a vessel that weighs say 3pounds

you displace the volume of air within it with helium

said helium produces half a pound of lift

what does the vessel now weigh?

go ask mr Zepplin about it... he might just put you right on a few points
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Old Mar 06, 2012, 08:44 PM
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I'm guessing it was built by the same guy who did the helium filled fuselage Airbus 330. the fuselage was some sort of membrane filled with helium. no internal structure, the wings probably depron. it flies just like this - there are videos of it somewhere here on RCG.
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Old Mar 07, 2012, 02:17 AM
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Quote:
Originally Posted by jonquinn View Post
I'm guessing it was built by the same guy who did the helium filled fuselage Airbus 330. the fuselage was some sort of membrane filled with helium. no internal structure, the wings probably depron. it flies just like this - there are videos of it somewhere here on RCG.
I dont think so that it can be depron because its quite heavy it should be something like paper covering !
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Old Mar 07, 2012, 09:14 AM
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Dear HM,

These are the basic math facts

The bouyant mass for 1 cubic meter of helium at sea level and 0 deg C is: .178 Kg * (1-(1.292/0.178))= -1.113 Kg. If the Cricri did have a volume of 1 cubic meter, the helium would reduce the weight by only 1.113 KG.

Why do you think the Zepplins were so big? They had to be so as to displace enough air to lift.
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Old Mar 07, 2012, 02:42 PM
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Quote:
Originally Posted by beerbrewer View Post
Dear HM,

These are the basic math facts

The bouyant mass for 1 cubic meter of helium at sea level and 0 deg C is: .178 Kg * (1-(1.292/0.178))= -1.113 Kg. If the Cricri did have a volume of 1 cubic meter, the helium would reduce the weight by only 1.113 KG.

Why do you think the Zepplins were so big? They had to be so as to displace enough air to lift.
Beerbrewer

well done... now we are getting somewhere!
you calculate 1 cubic metre of helium generates "only" 1.113kg of lift?

well lets look at the cri-cri... that canopy and fairing alone could easily hold 1 cubic metre of helium

now 1kg = 2.2 pounds so 1.113kg is near 2.5 pounds of lift

so if he built the model at 5 pounds weight and displaced the air with helium...

yep! his cri-cri now only weighs 2.5 pounds

and as "jonquinn" said... do you remember the helium filled airbus?

well i do and here it is... all 285grams at 2 metre span

for you guys in imperial measureland... thats.. 78" span and 10 ounces heavy (28.34 gram = 1oz)

Airbus A310 by MM - indoor airshow Leipzig [HD] (5 min 19 sec)



and no the film is not slowed down or photo-shopped or any other new fangled jiggery-pokery.... what you see is how it is... 9 servos, working slats and flaps with lights! that fuselage is an 80" long helium balloon with a nose cone

old Von Zepplin knew a thing or two about lighter than air

d
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Last edited by how much; Mar 08, 2012 at 12:10 AM. Reason: ounce conversion corrected... oops
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Old Mar 07, 2012, 03:35 PM
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and just to throw "a random one" in..

how heavy would a 1/3rd scale "piper" be ??? or could you fly a 1/3 scale Cub indoor?

lets see 120 4 stroke or 38cc petrol might just do it???


nope! watch and learn about lightweights..

modell-hobby-spiel 2011 - Piper PA-18 in Action (1 min 45 sec)



d
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