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Old Jul 05, 2011, 09:37 AM
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Bogota Colombia
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Some progress in the CAD design.
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Old Jul 05, 2011, 05:09 PM
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Bogota Colombia
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I had to change the airfoil on the root to a symetric one in order to host the landing gear strut. The airfoil at root transition to a clark

Y at the engine pylon. I have to check that the root stalls first than tip in this setup. Washout has been already included.
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Old Jul 05, 2011, 08:45 PM
EDF rules... :)
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Originally Posted by cetorca View Post
This is how it looks. There is the outer area which is the difference between the FSA and the Inner cone oulet area.
Hi CEtorca,

I think you will find that splitting the flows between the annular outlet and the cone will result in large losses in thrust.
If the annular outlet is too large the flow out of it will be following a greatly expanding area with a converging cone in the center causing the airflow to slow more than you expect which will result in poor thrust. The fluid will flow thru the path of least resistance so the annular outlet will need to be restrictive to force the fluid thru the conical outlet. It would be better to use the cone to control airflow for enhanced thrust, having two outlets will double the losses. It might need to be a little larger than scale but the performance will not deteriorate like the annular design and it won't be noticeable in flight.

Eric B.
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Old Jul 05, 2011, 10:32 PM
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could you not just go for a "profile" cone instead? just a flat sheet from the side and the bottom in an vertical "X". this way, it'll look like the real thing from the side and from the bottom as it's flying over you. this way, you'll just have one opening instead of two and it'll be less restrictive.
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Old Jul 08, 2011, 07:58 AM
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Originally Posted by AirX View Post
Hi CEtorca,

I think you will find that splitting the flows between the annular outlet and the cone will result in large losses in thrust.
If the annular outlet is too large the flow out of it will be following a greatly expanding area with a converging cone in the center causing the airflow to slow more than you expect which will result in poor thrust. The fluid will flow thru the path of least resistance so the annular outlet will need to be restrictive to force the fluid thru the conical outlet. It would be better to use the cone to control airflow for enhanced thrust, having two outlets will double the losses. It might need to be a little larger than scale but the performance will not deteriorate like the annular design and it won't be noticeable in flight.

Eric B.
Eric, it's a very wise advise and I've been thinking about it. What I came up yesterday, was to set up a test bench with the annular oulet and the center cone ,where the Red motor fairing shown in the graph is displaced horizontaly so you can control the amount of flow entering the converging cone. Measuring thrust and power you can determine where is the best position where the air is not slow to much due to the effect you explained. Then compare the results with the bench test without any of the cones, just the EDF itself and see if the losses are significant.
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Old Jul 08, 2011, 08:02 AM
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Originally Posted by LuvEvolution7 View Post
could you not just go for a "profile" cone instead? just a flat sheet from the side and the bottom in an vertical "X". this way, it'll look like the real thing from the side and from the bottom as it's flying over you. this way, you'll just have one opening instead of two and it'll be less restrictive.
You mean a cone a with flatenned sides?
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Old Jul 08, 2011, 10:04 AM
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like this

yes, it looks like complete crap, since I don't do CAD at all. and also, it looks like crap on the model too, but it's a compromise you may have to live with, unless you make a scale cone that is removable for flight. that's of course, if you find out that your thrust is too low with the setup as you have it drawn up. if it works, you'll be ok. just pointing out other options that might be used.
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Old Jul 09, 2011, 10:01 PM
EDF rules... :)
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Originally Posted by cetorca View Post
Eric, it's a very wise advise and I've been thinking about it. What I came up yesterday, was to set up a test bench with the annular oulet and the center cone ,where the Red motor fairing shown in the graph is displaced horizontaly so you can control the amount of flow entering the converging cone. Measuring thrust and power you can determine where is the best position where the air is not slow to much due to the effect you explained. Then compare the results with the bench test without any of the cones, just the EDF itself and see if the losses are significant.
Never hurts to put it to the test. Please post your numbers it will be interesting.

Cheers,
Eric B.
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Old Mar 05, 2012, 07:16 AM
ich bauen groß modell flugzeug
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Well what happened here then ??
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Old Aug 06, 2012, 09:12 AM
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Bogota Colombia
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Landing Gear

Hi;

I've been working on the landing gear. They are going to be pneumatic and as much as scale as my spare time will allow. Aluminum 6061, 2024 and 7075 is being used.
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Old Aug 06, 2012, 09:45 AM
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Lnd gear CAD

This is the render of my landing gear CAD. I did a custom retract since the commercial ones protrude out the wing skin if placed for a scale retract position.
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Old Aug 06, 2012, 09:56 AM
ich bauen groß modell flugzeug
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United Kingdom, London
Joined Dec 2010
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Cool Good to see you back at work on this 767 Can't wait to see it done! ... BTW there is an Airliner forum now!

Also would you consider milling me a set of gear as im doing a 767-300 some time soon
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Old Aug 06, 2012, 11:56 AM
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those look awesome. how do we get you to make a set of those for us? LOL.

Rich
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Old Aug 07, 2012, 09:31 AM
Firecracker!
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San Francisco & Santa Cruz
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On the exhaust issue, have you looked into using a smaller fan running at higher power? FSA will be less, so the scale exit may be possible (or at least something much closer).

The Minifan (70mm) FSA is 29.4 sq cm, while the Microfan (50mm) is 13.9 sq cm.

You would have to build light though!
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Old Aug 07, 2012, 02:34 PM
No worries... it can be fixed.
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Wow! Looks like a great project! Can't wait to see how it turns out.
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