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EDF pusher Jet scratch build- contest 2

Old 09-21-2010, 01:02 PM
  #51  
babylon5
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Default My own SPAD EDF jet

Hi Chellie, I have completed building the SPAD EDF tail-less jet.
The plane is ready for maiden this coming weekend if the weather hold.
Am looking forward to hiring the following during the maiden:-

1) a video camera man with a steady eye and capable of tracking a fast"mosquito "in the air.

2) a airplane launcher with a strong bungee like hand.

3) a couple of cheer leaders preferable with pom pom and sexy legs.

4) a trash collector (you get my drift).

Here is a couple of pictures taken before it has the chance to "change shape"

If this plane is proven to a successful fly , I will be planning some pusher and traction configuration in future.


Cheers
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Old 09-21-2010, 08:10 PM
  #52  
CHELLIE
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That Looks Super nice Good luck to you on its maiden flight here is a nice way of tracking a fast plane. set your zoom to 1/4 to 1/3 and follow the plane with the open sights, sight the camera and the open sights on a object about 100 feet away, hope that helps, BTW my legs are way to sexy and might start a RIOT

http://www.wattflyer.com/forums/show...ighlight=rifle
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Old 09-26-2010, 06:29 AM
  #53  
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Default My own SPAD Jet part2

Hi, today weather was great with a gentle breeze blowing from the west of the flying field. A good day to maiden the experimental SPAD EDF jet.
First attempt to use the 1250mah 3S lIpo fail to launch due to tail heavy.
I replace it with a 1750mah 3S lipo and she flew. It was fast when you open up the throttle.

"Thrash Collector was already waiting to collect my plane. Lucky for me his service was not required".

Here are the video of the maiden.
The landing was hard due to the untrimmed elevator.
Second launching fails because the fuselage was already crooked by the previous hard landing and fail launch.
Need to rebuilt a better fuselage. More next time.

Here are the video link

[media]http://www.youtube.com/watch?v=GhcjdyppgZo[/media]

...and some static picturres. The "clip wing Mugi next to the Tail-less SPAD is just for comparison.

Thanks for viewing
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Old 09-26-2010, 11:47 AM
  #54  
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It flies great Babylon5 You just need to work on your Landings Take care and Have fun, Chellie
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Old 12-31-2013, 08:58 AM
  #55  
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Default any plans?

Any plans?
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Old 12-31-2013, 09:29 AM
  #56  
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Originally Posted by CHELLIE View Post
That Looks Super nice Good luck to you on its maiden flight here is a nice way of tracking a fast plane. set your zoom to 1/4 to 1/3 and follow the plane with the open sights, sight the camera and the open sights on a object about 100 feet away, hope that helps, BTW my legs are way to sexy and might start a RIOT

http://www.wattflyer.com/forums/show...ighlight=rifle
My pal Andrejs is a brilliant Video guy and I just give him my old trusty Sony 8mm and away he goes.



Digitals are ok - but I find that usually you cannot see anything in the screen so needs an eyepiece viewfinder.

Andrejs and I both found that once we get the model in the eyepiece - that's best and we follow ... If we try with screen - we lose it repeatedly.

The other good thing about the old 8mm Handycam - is the zoom ... I've yet to see a digital job as good.

[media]http://www.youtube.com/watch?v=9wAUkHV89dI[/media]

Nigel
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Old 01-01-2014, 01:48 AM
  #57  
kiwichristian
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Originally Posted by CHELLIE View Post
Thank You Jim for the Complement It was a fun build, and it flys great, I am very happy with it, Take care, Chellie
Any plans available, please?
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Old 01-01-2014, 06:13 AM
  #58  
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Originally Posted by kiwichristian View Post
Any plans available, please?
Hi I am going to build another one of these soon, I found out that the EDF needs to be mounted more towards the center of the plane, it flies good, but if you stall it, it will go into a flat spin, so i have to move the weight of the EDF more towards the centre, i will get back to you soon, Take care, Chellie
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Old 01-01-2014, 06:40 AM
  #59  
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For many pusher designs you have to chop power to recover from a spin.
Usually a symptom of having lots of torque and no air being blown over the control surfaces, applying high power will just wind up the spin and make it tighter.
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Old 01-01-2014, 08:45 AM
  #60  
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Originally Posted by fhhuber View Post
For many pusher designs you have to chop power to recover from a spin.
Usually a symptom of having lots of torque and no air being blown over the control surfaces, applying high power will just wind up the spin and make it tighter.
There's a very simple example that anyone can do to illustrate this :

Bowl of water. Matchstick or thin stick. Lay it on the water.
Pull it by front end and it follows straight ... emulates the power out of spin of a tractor prop.
Now PUSH the rear end of the stick and the stick will flip round as the front resists movement - emulates the pusher prop and the models flip with power on.

It gets worse as the centre of power output moves away from model's longitudinal centre line and it's CoG.

It's also why as you increase power on pushers - the hand-launches become more of a prayer than a g'teed success !

Nigel
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Old 01-01-2014, 09:20 AM
  #61  
kiwichristian
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Originally Posted by CHELLIE View Post
Hi I am going to build another one of these soon, I found out that the EDF needs to be mounted more towards the center of the plane, it flies good, but if you stall it, it will go into a flat spin, so i have to move the weight of the EDF more towards the centre, i will get back to you soon, Take care, Chellie
Thanks, i will look forward to it.

How about mounting it in the nose?
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Old 01-01-2014, 10:47 AM
  #62  
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Originally Posted by kiwichristian View Post
Thanks, i will look forward to it.

How about mounting it in the nose?
I am also thinking about mounting a 1800kv - 2000kv outrunner motor in the nose, with a 7x6 prop, i think it will be faster with a prop i am ordering a 55mm edf from HK right now, I have been wanting to get a simple edf pusher jet on the market, or at least on my EBay selling site LOL, Take care, Chellie
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Old 01-01-2014, 02:50 PM
  #63  
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Happy New Year Chellie,

Had I known you needed an edf, I'd give you one of my Jpowers 50mm or a 66mm w/nacelle from an eflight airliner.

All the best in 2014 !
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Old 01-01-2014, 07:07 PM
  #64  
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Originally Posted by dahawk View Post
Happy New Year Chellie,

Had I known you needed an edf, I'd give you one of my Jpowers 50mm or a 66mm w/nacelle from an eflight airliner.

All the best in 2014 !
Happy New Year Hawk
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Old 01-01-2014, 07:25 PM
  #65  
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EDF is really an inefficient way to power a model. You generally need 50% more watts for the same performance vs a propellor and that means you end up heavier and/or have shorter flight duration.

But there is a cool factor to the EDF.
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Old 01-01-2014, 10:53 PM
  #66  
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Chelster,
Let me know and I'll send you one
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Old 01-19-2014, 12:32 AM
  #67  
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Better late than never

http://bigconkers.com/projects/big-c...ctric-jet-bike
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Old 01-19-2014, 01:33 AM
  #68  
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Cool! Now if they swapped those edf's for appropriate props...
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Old 01-19-2014, 09:33 AM
  #69  
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Originally Posted by solentlife View Post
There's a very simple example that anyone can do to illustrate this :

Bowl of water. Matchstick or thin stick. Lay it on the water.
Pull it by front end and it follows straight ... emulates the power out of spin of a tractor prop.
Now PUSH the rear end of the stick and the stick will flip round as the front resists movement - emulates the pusher prop and the models flip with power on.
Doesn't work that way with props Nigel, if it did ships wouldn't have their props at the back would they?

The difference is that on air-planes (and ships) the thrust vector is always aligned with the axis of the plane/ship, because the prop is fixed to the plane/ship, this is a stable configuration. When you push something with your finger there is a 'pivot' where your finger connects to the object, so your 'push' is not always aligned with the axis, therefore it becomes unstable.

Truth is that in normal flight pushers are actually more stable than tractors. The prop acts like a tail and stabilises the plane. This is the reason why you will never see a finless flying wing with a tractor prop, or at least you wont see one that flies! Yet finless pushers can fly ok.
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Old 01-19-2014, 04:23 PM
  #70  
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I have to agree with Nigel on this one, especially at lower airspeed. I do agree with what you say about the prop stabilizing it when at speed though, but until it gets up to that speed, yes that thrust angle better be just right, as well as the launch angle. You don't see any 3d pusher planes, after all. And yes, I understand 3d planes need the prop wash over the control surfaces.
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Old 03-30-2014, 08:40 AM
  #71  
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Default Very interesting model

Could you post the plan?
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Old 03-30-2014, 09:55 AM
  #72  
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Originally Posted by JetPlaneFlyer View Post
Doesn't work that way with props Nigel, if it did ships wouldn't have their props at the back would they?

The difference is that on air-planes (and ships) the thrust vector is always aligned with the axis of the plane/ship, because the prop is fixed to the plane/ship, this is a stable configuration. When you push something with your finger there is a 'pivot' where your finger connects to the object, so your 'push' is not always aligned with the axis, therefore it becomes unstable.

Truth is that in normal flight pushers are actually more stable than tractors. The prop acts like a tail and stabilises the plane. This is the reason why you will never see a finless flying wing with a tractor prop, or at least you wont see one that flies! Yet finless pushers can fly ok.
Actually my description 'holds water' and is correct. the reason a ship doesn't actually flip or screw round is rudder forces and also buoyancy.

But ask any powerboat racer ... particularly the extreme power boys.

What I am illustrating is the inertial or resistance of the forward section to move when pushed.

Tail-less craft owe stability not to tail mounted power but authority of control surfaces.

Nigel
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Old 03-30-2014, 06:55 PM
  #73  
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Hi Chellie,
Where I can find the project of the model you showed at the beginning of this post in the 2008?
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Old 03-30-2014, 07:15 PM
  #74  
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Originally Posted by smartglider View Post
Hi Chellie,
Where I can find the project of the model you showed at the beginning of this post in the 2008?
Hi I am going to modify this jet a little and move the edf forwards more and make it a little longer, it had a tendency to stall and not recover if it slowed down to much, to much mass at the rear, I would say in a few weeks I will redo this project, so it flies and wont flat spin and stall, Take care, Chellie
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Old 03-30-2014, 08:51 PM
  #75  
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Thank you very much again from Italy...
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