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-   -   Big Concorde (http://www.Wattflyer.com/forums/showthread.php?t=73330)

CHELLIE 03-12-2014 12:11 AM

Big Concorde
 
Here is one for Nigel :D Make one this Size :eek: ;-)


tobydogs 03-12-2014 01:00 AM

thats one large bird!!! at first i thought it was a joke when he powered up and nothing around him was blowing ,he even seemed to stand directly behind it, set it for launch and nothing blowing.not the weeds behind him or his pants:confused:...but the actual flight and landing looked and sounded very cool.

solentlife 03-12-2014 01:10 AM

Unfortunately until I depart China ... I cannot watch or link to any Youtube vids !

Nigel

solentlife 03-12-2014 01:14 AM

One question I have ....

At what size would a Concorde have to be so we could actually build a reasonably powered model scale with EDF's ...

Small EDF's are terribly inefficient and also large for their performance, making nacelles over-size etc.

Quorneng is trying with 4 x 40mm's ..... I built with 2 x 50mm's and ended up compromising more than originally intended.

It's one of those models that needs turbine's to stay scale.

Nigel

thepiper92 03-12-2014 03:58 AM

Is it tail heavy or are Concordes supposed to fly in such a way?

solentlife 03-12-2014 05:05 AM

Quote:

Originally Posted by thepiper92 (Post 942280)
Is it tail heavy or are Concordes supposed to fly in such a way?

Tail heavy does not decide angle of flight, but the pitch sensitivity.

A tail Down attitude is an incidence with speed / lift related problem and can be altered by changing main wing / tail surfaces rigging angles.

Concorde has a near zero AoA in rig as the speeds are such that any small angle is amplified in effect compared to normal subsonic aircraft. It also is one of the main reasons she moves weight around in flight depending on speed.
The design is such that at model speeds she will exhibit a nose up of tail down tendency.

Nigel
Wattflyer Concorde flyer! ;)

kyleservicetech 03-12-2014 05:37 AM

[QUOTE=CHELLIE;942255]Here is one for Nigel :D Make one this Size :eek: ;-)

Wow
Don't even want to know what it cost to build that thing!

Agreed, it sure looked a bit tail heavy.

thepiper92 03-12-2014 05:42 AM

Maybe a little over my head lol. A Concorde has a high angle of attack at low speeds to create lift that would be lacking from the small wing span correct? I have never really read into how they work until now. Even so, the Concorde in the vid does seem to be very sensitive and constantly flying at a high angle attack, not just at low speeds. It looks like it will fall out of the sky at any point to me.

kyleservicetech 03-12-2014 05:44 AM

Quote:

Originally Posted by thepiper92 (Post 942288)
Maybe a little over my head lol.

LOL
Yeah, way over my head also, and a mile over my budget! :eek:

thepiper92 03-12-2014 05:55 AM

Seems hard to find the cg of a plane that is always shifting its balance in relation to speed. Perhaps throw weight in any place and if it stays up there, it's good to go.

CHELLIE 03-12-2014 06:41 AM

Quote:

Originally Posted by solentlife (Post 942269)
Unfortunately until I depart China ... I cannot watch or link to any Youtube vids !

Nigel

Bummer on the Videos, I Would Say this rc plane is about 15 ft long with a W/S of about 8 ft. Judging by the size of the Pilot, the concord did look to be tail heavy and sensitive on the controls.

I would think that a 12 ft wood stick frame concorde covered with 2mm depron would work well with 2- 90mm edf at 6.0kg of total thrust or 6.6 lbs of thrust each or 13.2 lbs of thrust total if the weight of the concorde is keep to around 15 -18 lbs AUW, Just my 2 cents worth :ws:

http://www.hobbyking.com/hobbyking/s..._1750watt.html

CHELLIE 03-12-2014 07:49 AM

I Thought this was neet :)

http://www.dream-rc-airplanes.com/concorde.html

http://www.dream-rc-airplanes.com/concorde2.html



http://www.dream-rc-airplanes.com/im.../small_041.jpg


http://www.dream-rc-airplanes.com/im...e/IMG_0369.JPG

http://www.dream-rc-airplanes.com/im...e/IMG_0371.JPG

CHELLIE 03-12-2014 07:59 AM

Interesting Fact.

WARNING SCIENTIFIC CONTENT : In a twin engine jet plane, it is key to point each engine away from the center line a few degrees. The offset of the two engines cancelled the effect while they are both running. If one motor should stop the thrust in the remaining engine will help fly it in a straight line. Not everyone knows that about twin jets

CHELLIE 03-12-2014 08:11 AM


CHELLIE 03-12-2014 08:16 AM


CHELLIE 03-12-2014 08:24 AM

Its not E Powered but still neet :)
 

JetPlaneFlyer 03-12-2014 08:46 AM

Quote:

Originally Posted by thepiper92 (Post 942291)
Seems hard to find the cg of a plane that is always shifting its balance in relation to speed.

The only time Concord 'shifted it's balance' was during transition between sub-sonic and supersonic flight. This is due to the shift in aeodynamic centre from 25% chord to 50% chord when you go supersonic.

This isnt an issue at model scale unless you actually plane of breaking the sound barrier.

The only other planes that 'shift balance' that I can think of are hang-gliders that are controlled by body movement.

JetPlaneFlyer 03-12-2014 08:58 AM

Quote:

Originally Posted by thepiper92 (Post 942288)
Maybe a little over my head lol. A Concorde has a high angle of attack at low speeds to create lift that would be lacking from the small wing span correct?

No, actually Concorde had quite a lot of wing area compared to a conventional airliner.

The reason it has to fly at such high angle when going slow is twofold:
  1. Tailless deltas can't use conventional flaps, so rather than using flaps to increase lift angle of attack has to be increased.
  2. The slope of the lift curve is related to aspect ratio of the wing. High aspect ratio (long and slender) wings have a steep lift slope, so relatively small changes in angle of attack make relatively large changes in lift. Very low aspect ratio wings (like Concorde) have a very 'flat' lift slope, so you need large changes in angle of attack to increase lift. Also stall angle is much higher on low aspect ratio wings which means they can achieve these high angles without stalling, as a conventional plane would if you tried to do the same thing.
here's a graph that illustrates the aspect ratio 'thing':
http://www.pilotfriend.com/training/...o/images/7.gif

Taken from this web site: http://www.pilotfriend.com/training/.../aero/lift.htm

and FWI.... Flying 'tail down' IS NOT a sign that the plane is tail heavy. A tail down attitude would usually mean that the plane was flying slowly and/or it was heavy.

solentlife 03-12-2014 10:40 AM

Quote:

Originally Posted by JetPlaneFlyer (Post 942311)
No, actually Concorde had quite a lot of wing area compared to a conventional airliner.

The reason it has to fly at such high angle when going slow is twofold:
  1. Tailless deltas can't use conventional flaps, so rather than using flaps to increase lift angle of attack has to be increased.
  2. The slope of the lift curve is related to aspect ratio of the wing. High aspect ratio (long and slender) wings have a steep lift slope, so relatively small changes in angle of attack make relatively large changes in lift. Very low aspect ratio wings (like Concorde) have a very 'flat' lift slope, so you need large changes in angle of attack to increase lift. Also stall angle is much higher on low aspect ratio wings which means they can achieve these high angles without stalling, as a conventional plane would if you tried to do the same thing.
here's a graph that illustrates the aspect ratio 'thing':
http://www.pilotfriend.com/training/...o/images/7.gif

Taken from this web site: http://www.pilotfriend.com/training/.../aero/lift.htm

Plus the wing is thin and does not generate large lift by virtue of thick form., It literally mimics a flat plate as we use !

Quote:

and FWI.... Flying 'tail down' IS NOT a sign that the plane is tail heavy. A tail down attitude would usually mean that the plane was flying slowly and/or it was heavy.
Or as I mentioned ... a low angle of incidence main wing .... also that Concorde is a Composite Form Delta ... delta's will pitch up and fly much higher than a conventional craft.

Watch my 4S video of twin EDF ... on the landing ... angle is at least 25 - 30 deg's.

If you want to scare the 'pants' of yourself - try a Mirage 2000 or 4000 model with good power ... I had a 61 Glow powered nose mounted prop job ....... the angles of attack she could hold in STEADY flight were frightening ...

Nigel

DEG 03-12-2014 06:04 PM

Nigel,

You start thinking about that one, you gonna have to help my fund a BIGGGG monitor....:)

fhhuber 03-12-2014 06:56 PM

I expect that if you keep weight down and use 4 of the Dynam/Detrum (low cost http://www.nitroplanes.com/60p-70mm-edf-combo.html) 70 mm fans you could do a fairly large Concord with near-scale engine nacelles.

This is based on the stock out of box twin 70mm EDF Dynam Me-262's performance being nothing short of outstanding.
Low cost and light weight EDF units that put out very good thrust and have been very reliable. (over 500 flights in 1 year and still going)


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