Prop stopped.

[Garfly]

16 minutes ago, IBob said:

And that's really cleaned up and fast for a Jodel. Very small air intakes......

 

Yes, and if you read his blog around 2018/19 you can see that the clean lines are no accident (a random sample):

 

 

"January 1st. 2019
Cover, oil cooling air outlet.

First of all, happy new year to all and full of success in what you are about to undertake.

For my part, I hope to beat a new speed record this year and fly at more than 130 kt.

 

 

 

 

I don't like to redo what I've already done, but yet it was necessary to redo the oil cooling outlet air duct for the new hood.
However, I made a few minor changes. First a curvature a little more studied than the original basic bend (first photo) with a slightly larger bend radius and a slight converging in the bend to locally accelerate the flow and avoid separations in the bend. Finally, the outlet on the cowl side will be flatter for better integration of the outlet flow into the general external flow.  The part was therefore laminated with epoxy on a polystyrene male mold covered with tape, as usual.
The exit is also more oriented upwards by an additional 5°, ie well parallel to the external air streams which at this point rise to bypass the leading edge of the wing towards the upper surface (observation by film of oil).
Finally, the output section is slightly decreased (-15%), which will decrease the flow a little, but will increase the output speed. Indeed, the cooling of the radiator has never been insufficient, even in hot weather, so I think I have a little margin to try to optimize this cooling trail."

 

Full blog:

 

https://speedjojo-blogspot-com.translate.goog/search?updated-max=2019-02-01T18:21:00%2B01:00&max-results=2&start=27&by-date=false&_x_tr_sl=fr&_x_tr_tl=en&_x_tr_hl=en&_x_tr_sch=http

[Mike Gearon]

14 hours ago, IBob said:

 

Regarding my Plane Crash YouTube links above, the pilot has not thought it through. The reason his fuel has gassed in the pipes is the elevated temperature in the engine compartment. Ideally, his fuel system should have a return that moves that gas, and the heat it contains, out of the engine compartment (as per Rotax recommendations), replacing it with cooler fuel. But what he has put in is a short loop that simply recirculates gas and heat under the hood, because somebody has told him this will fix the problem. That's what's called magical thinking.

 

Finally, since I wrote 'detail': note the fine fuel filter before pump and return etc in the Rotax recommended fuel system. This prevents not only carburettor jet blockage, it also prevents blockage of the orifice in the fuel return, and ensures the pressure relief bypass in the electric pump seats properly.

Yes, I’ve paid attention here. The tiny orifice of the return line necessary to maintain pressure and obviously to limit fuel return flow. Say 30 minutes and 10 litres to a wing tank as acceptable and 20 litres as way too much. Balancing act between keeping the fuel cool/ vapour exit and not returning an unmanageable amount of fuel.

 

Bottom line the small orifice can’t be avoided and unlikely still but still possible to block hence fuel strainer should be before the orifice. I’ll be checking and changing if needed on mine.

 

Magical thinking. 🙂 That was sure a dumb idea with that line. Not a shred of critical thought. Even if it went forward to cool airflow and through a little fuel radiator you’d still be left without an exit for vapour/ bubbles. Just has to go all the way back to tank with breather.

Edited June 16, 2022 by Mike Gearon

[RFguy]

any sort of fluid flow regulator in fluid world that doesnt involve a small orifice ?

 

[Thruster88]

Tesla valve? 

[RFguy]

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

 

https://www.machinedesign.com/mechanical-motion-systems/article/21164409/the-tesla-valve-bringing-back-a-forgotten-invention?gclid=CjwKCAjwqauVBhBGEiwAXOepkZbukSSZX8V3NxOmS2O7OQMISEit3U7EtPogZPL3nafKZlELvH2I1BoCJKcQAvD_B

 

I am sure there will be plenty of people here with backgrounds that can suggest something to return at 1 litre per minute over a wide range of pressure.

Edited June 16, 2022 by RFguy

[facthunter]

Not so easy. Everything added makes something else to go wrong.  Nev

[Garfly]