Renovation and aerodynamic improvement of a BPW closed trailer

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Macro
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Re: Renovation and aerodynamic improvement of a BPW closed trailer




View Macro » 24/10/22, 17:57

That said... In your opinion... Which of these two vehicles is more difficult to drive in crosswind or gusty conditions...
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Remundo
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Re: Renovation and aerodynamic improvement of a BPW closed trailer




View Remundo » 25/10/22, 14:21

great job Christophe

both in prototype and modeling in fluid mechanics.

:)
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Christophe
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Re: Renovation and aerodynamic improvement of a BPW closed trailer




View Christophe » 25/10/22, 22:11

Macro wrote:That said... In your opinion... Which of these two vehicles is more difficult to drive in crosswind or gusty conditions...


If the side wind is too strong, speed up!! (jc van dam) : Mrgreen:
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Obamot
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Re: Renovation and aerodynamic improvement of a BPW closed trailer




View Obamot » 26/10/22, 04:21

Macro wrote:That said... In your opinion... Which of these two vehicles is more difficult to drive in crosswind or gusty conditions...
the kul-brick, Stan ugly : Mrgreen:

(Nothing personal, I've never seen you)
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Macro
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Re: Renovation and aerodynamic improvement of a BPW closed trailer




View Macro » 26/10/22, 06:49

Well...the brick ass is much more stable than the ball...and yet it no longer has a stab bar or a panhard bar
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Re: Renovation and aerodynamic improvement of a BPW closed trailer




View Christophe » 26/10/22, 13:44

What difference in Macro mass…what rolling and crosswind speed?

Listen a little JCVD : Mrgreen:
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Re: Renovation and aerodynamic improvement of a BPW closed trailer




View Christophe » 27/10/22, 12:36

Tadaaaammmm, yesterday was the weighing...

I can't take readable photos with the LCD of the scale, it flashes too much..

173 kg on each wheel
50 kg on the drawbar
= 396 kg


I had 69 kg of safety load at the front when weighing, so the weight of the empty trailer: 327 kg knowing that it was originally 290 kg.

So I weighed down the trailer by 37 kg, knowing that there is about 25 kg of PVC siding...(which was not structurally useful).

In other words: my aerodynamic additions only brought a 12 kg overweight for efficiency and storage volume... (I changed the axle too...but didn't do any differential weighing)

I have a payload of 423 kg...let's say 350 kg with the safety margin. It's much more than I need but it goes quickly!

Regarding safety and according to the comparative analyzes of Solidworks, the rear part creates a lift of about 60 kg...located about 2.7 m from the axle of the wheels...

At 130 km/h, I therefore have a tilting moment on the drawbar of 600 * 2.7 = 1620 Nm is not nothing at all as a moment of safety... but it is at 130...

I'm going to redo a simulation at 90 and 60 km/h...just out of curiosity...

ps: the rear floor is still missing...
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Re: Renovation and aerodynamic improvement of a BPW closed trailer




View Christophe » 27/10/22, 13:01

While waiting for the moment simulations at 60 and 90 km/h, here are the results of the flows around a "perfect" trailer*:

Pressure in the plane and RRF velocity on the points:

Summary_perfect_trailer.png
Résumé_remorque_parfaite.png (144.2 KiB) Viewed 838 times


* almost perfect, because it creates 40 kg of lift at the front, which creates a tilting moment which can be dangerous (depending on its point of application and where the wheels are, which must therefore be strongly forward on a trailer of this type ...or double axle...)...
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Christophe
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Re: Renovation and aerodynamic improvement of a BPW closed trailer




View Christophe » 27/10/22, 15:15

Simulations at 60 and 90 km/h

60 km/h

Rear lift: 10.5 kgF
Power: 3,5 hp (you can pull it with a slightly doped moped!! : Mrgreen: )

90 km/h

Rear lift: 29,7 kgF
Power: 13,1 hp

So even at only 60 km/hy there is an interesting safety torque of 105 * 2.7 = 280 Nm towards the drawbar... 8) 8) 8)
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Re: Renovation and aerodynamic improvement of a BPW closed trailer




View gildas » 27/10/22, 15:27

Aerodynamics imposes significant shapes on vehicles which must then resist side winds, ideal for housing a large battery to stabilize everything!

*In principle Marco's i miev must be more stable than the 4X4...
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