Random Aerodynamic Oddity of the Day Thread

[kach22i]

Originally Posted by Piotrsko

I fail to see how they have the same thrust as a long aspect rato prop that uses the same input power.

I also don't understand what the patent is about. ROHR was doing similar things 25 years ago

I view it as more of an adaption of the Turbo-Fan as it is basically an electric jet motor, something I've been interested in for the last 15-20 years or so for my hovercraft designs that I do for fun.

Here is what I mean, in lieu of the fan part of the turbo-fan they have only an annular inlet (w/folding plates).

In lieu of the turbine element of the turbo-fan they have a fan or propeller.

https://en.wikipedia.org/wiki/Turbofan


I'm sure at some time in the past some testing facility modeled or tested a turbo-fan with the fan removed using only the center turbine part.

This would be a jet engine with shrouded air cavity where air could be squeezed or expanded depending on velocity and pressure desired when it merges with the jet gasses at the end. Sort of a Ram Jet but not quite.

As I understand it, in a turbo-fan the fan produces 90% of the thrust, the turbine and hot jet exhaust only the remaining 10% but I could be wrong (flying off of memory here).

[kach22i]

Originally Posted by Piotrsko

I fail to see how they have the same thrust as a long aspect rato prop that uses the same input power.

I also don't understand what the patent is about. ROHR was doing similar things 25 years ago

ROHR was just a ducted fan/propeller from what I can tell, a very cool one though.

Using the search term "Hoversurf" in Google Patents I could not find anything.

I'd like to see their patent, please post it if you find it - that goes out to anyone reading this. I have to get back to work.

[euromodder]

Originally Posted by kach22i

I'm sure at some time in the past some testing facility modeled or tested a turbo-fan with the fan removed using only the center turbine part.

This would be a jet engine with shrouded air cavity where air could be squeezed or expanded depending on velocity and pressure desired when it merges with the jet gasses at the end. Sort of a Ram Jet but not quite.

You're essentially describing the J58 engine in the A12 / YF-12 / SR-71 Blackbird ...

[kach22i]

Originally Posted by euromodder

You're essentially describing the J58 engine in the A12 / YF-12 / SR-71 Blackbird ...

Kind of, minus the introduction of fuel at the end called an afterburner of course.

Pratt & Whitney J58
https://en.wikipedia.org/wiki/Pratt_%26_Whitney_J58

The J58 was a single-spool turbojet with an afterburner.[1] It had a unique bleed from the compressor to the afterburner which gave increased thrust at high speeds.[2] This feature caused it to be referred to as a turboramjet in some writings.

Doing a search on the turboramjet topic I found a combination that I have never seen before.

Commercial Near-Earth Launcher: Propulsion Choices
https://link.springer.com/chapter/10...-662-54744-1_4


The point of this discussion I believe is to explore the introduction or reintroduction of airflow and or pressure differentials at the nozzle exhaust of a ducted fan/propeller/jet thrust system.

These gadgets or approaches are every bit as important as business at the front end, typically the increases in efficiency of a bell-mouth curve inlet.

EDIT:
I found a video showing the electric fan (cold jet - my own term) Venturi engine by Hoversurf.


Flying car scale model first test flight using Venturi EDF

https://www.youtube.com/watch?v=DaoOQoekfow

Hoversurf is well known for our Hoverbike. We know that propellers scare people and for the last few years we have been working very hard on our patented Venturi EDF technology. We are excited to present our 1:10 scale model of our future flying car that utilizes our Venturi EDF. This technology is safer, more compact, eco friendly and will replace propellers on all our future products. Thank you to all our subscribers and for your comments, we look forward to changing the future together.

[freebeard]

http://justacarguy.blogspot.com/2018...with-this.html

Boxed cavity on a Porsche 356.

[kach22i]

Originally Posted by freebeard

Boxed cavity on a Porsche 356.

I saw pictures of that before but did not really consider it a box cavity until you pointed it out.

Thanks for the link, I never saw the front before.

[kach22i]

This looks like too much fun, he has the quick fabrication skills for doing experiments that I admire.

He's moving air, so it is aerodynamically related.

Blower impeller design experiments

https://www.youtube.com/watch?v=YuEaP9kyiFc

Comparing forward curved blades, backward curved blades and straight blades for a blower impeller.

I see now why hovercraft use the straight and backward curved for high pressure lift fans.

[freebeard]

Bubble-top coupe before the Mustang.


Just A Car Guy: 1956 Chevy clay model, with a mix of ideas, gullwing doors from a Mercedes, fins from a Cadillac, and the split rear window

[Frank Lee]

You mean 'Vette?

[freebeard]

Oh, yeah; these's even one in the background.

When I think bubbletop coupe, I think Volvo P1800, Mercedes 300SL, Mustang fastback, etc. The Stingray is more a fastback like the Riviera.

It's all in the tulip panel.