To Wheel Or Not To Wheel ?

[All Darc]

This is not the news I saw a couple years ago, but it's also interestinh :

https://phys.org/news/2015-04-world-...-aircraft.html

5KW por kg... impressive. Industry have less than 1KW per KG in general.

If we compare to bicycle electric motor, heavy and low power.

[kach22i]

Originally Posted by All Darc

This is not the news I saw a couple years ago, but it's also interestinh :

https://phys.org/news/2015-04-world-...-aircraft.html

5KW por kg... impressive. Industry have less than 1KW per KG in general.

If we compare to bicycle electric motor, heavy and low power.

From the link:

Since the new motor delivers its record-setting performance at rotational speeds of just 2,500 revolutions per minute, it can drive propellers directly, without the use of a transmission. "This innovation will make it possible to build series hybrid-electric aircraft with four or more seats," said Frank Anton, Head of eAircraft at Siemens Corporate Technology, the company's central research unit.

Read more at: https://phys.org/news/2015-04-world-...craft.html#jCp

Thanks for posting this.

[All Darc]

Not sure if was the manufacturer I saw once, and the page change design, but the look of the motors are similar:

http://www.phi-power.com/en/phi-power-motor-series/



How add aerodynamic to this single person vehicle ?

https://www.youtube.com/watch?v=037CAW4Yeug

[All Darc]

I talked with a aerodynamic engeneering, and he is working in a new shell desigh, that according hin will be much more stable and quite more efficient than Morelli shape.
He told me it will have more than 50% laminar airflow on surface.

Just to remamber about laminar airflow, that it it's not all the air following the countorns, but a bit more difficult than that :



So, I wonder if it with wheels will got 0,09 or 0,08.

[freebeard]

Wings travel in free air, in gusty, crosswind conditions. Ground vehicles travel in the turbulent flow on the ground. A wind tunnel would need a turntable and moving deflectors to simulate real world conditions.

For the Bio-Hybrid, I'd look to the Tropfenwagen. I'd be tempted to do a appearance like the original with the surfboard fenders.

[All Darc]

I also talked with the designer of Fusion (4 riders 3 wheels Human Power Vehicle using Morelli's shape ).



He told me that back then (1984/1985) they could test it in a wind tunnel, but made controlled coasting tests on a measured incline, and the result estimation was CD: 0,09.
Quite good. Aptera Typ 1 had CD:0,11, and the production version (ugly compared to type-1) had CD:0,15






I'm curious about a video of controlled coasting tests. Can somebody help ?

Originally Posted by freebeard

Wings travel in free air, in gusty, crosswind conditions. Ground vehicles travel in the turbulent flow on the ground. A wind tunnel would need a turntable and moving deflectors to simulate real world conditions.

For the Bio-Hybrid, I'd look to the Tropfenwagen. I'd be tempted to do a appearance like the original with the surfboard fenders.

[freebeard]

My thought would be a highly streamlined tow vehicle and a looong tow rope with a spring scale that can be viewed from one vehicle or the other.

[aerohead]

Originally Posted by All Darc

I talked with a aerodynamic engeneering, and he is working in a new shell desigh, that according hin will be much more stable and quite more efficient than Morelli shape.
He told me it will have more than 50% laminar airflow on surface.

Just to remamber about laminar airflow, that it it's not all the air following the countorns, but a bit more difficult than that :



So, I wonder if it with wheels will got 0,09 or 0,08.

Remind your friend that laminar forms are only for 'flight' conditions,at high altitude,far away from ground effect,in perfectly-calm air.
As a motor vehicle,and full-sized,generally,the vehicle will be submerged in the turbulent boundary layer of Earth's troposphere,which can be kilometers deep!
We know from Ludwig Prandtl's research of 1907,that any crosswind component will contaminate a laminar boundary layer,forcing an immediate transition to a fully turbulent boundary layer.
Faisal Ahmed,in his Master's Thesis research reported that his pickup truck had a maximum of 30mm of laminar boundary layer.A little over 1-inch.
The only way you could have a 'laminar' body in ground proximity,would be on a closed course,with no traffic,on a completely calm day,and keep your velocity below 20-mph.Otherwise,it's scientifically impossible.

[All Darc]

It's possible to built Morelli's from this single technical drawing, since the lower part of the drawing represents the top view (cut in two in the drawing).



The explanation I got from a nice engineer :


"The image was copied from an SAE technical paper written my Morelli. It contains all the information you need to make a duplicate. It is what we used. Each cross section of the Morelli shape is a perfect ellipse. That major diameters of each ellipse are obtained from the top view. The minor diameters are obtained from the side view. All the intermediate points around the perimeter of each cross section can be calculated from the standard equation of an ellipse (see internet references).

If you want to create the best possible copy, I suggest you import the top and side views into a CAD program, like Inventor or Solidworks. You can then construct a very accurate 3D model using the CAD tools. It may take some time, but it can be done by someone who knows CAD. This way, you can also use a 3D printer to make a scale model. "

I overlayed it to Aptera Shape, and let the "cut off tail" adjusted, since Aptera cut off a bit of the Morelli's "tail" that should enf in a fine line. It got close, but it's not exactly Morelli.




http://i64.tinypic.com/2hobk2t.jpg

[freebeard]

IMHO the cross section shouldn't be oval in ground proximity. More flatten on the bottom or a rounded triangular shape like the ME-262. FWIW.