grill "shield" rather than block?

[winkosmosis]

Mi24 Hind helicopters have a shield like that on the engine.

http://www.asiatradingonline.com/Mi24-Hind.jpg

[Piwoslaw]

Originally Posted by winkosmosis

Mi24 Hind helicopters have a shield like that on the engine.

http://www.asiatradingonline.com/Mi24-Hind.jpg

Isn't that to keep birds out? Hmm, maybe that is what Lunar is up to

[lunarhighway]

Isn't that to keep birds out?

most likely they're more interested in keeping bullets and chrapnell out, but provided they make it trough the rotor in one piece birds could down the thing too.... belgian SAR seakings have a truck style deflector in front of the engines to keep seabirds out, though it's probably not designed for what i want the hind shields actually describe the setup i had in mind best....

since these engines suck in their air they probably don't rely much on ram effect... sort of the same as the radiator with the fan on!

[lunarhighway]

that falcon grill looks deceptively simple... some 80's cars had surprising good aero despite their boxy looks, perhaps i might also esperiment with adding some vertical slats in front of the grill...

i've also considdered a double grill, where there's two rows of vertical slats where the second row visually blocks the first but there's a space between them so the theoretical volume of air that could enter is the same.

[Piwoslaw]

Lunar, I just remembered that a few days ago cfg83 started this thread showing how he made a spring loaded grill block. At small speeds it is in the open position, but when going faster the wind closes it. When slowing down it opens again. This is pretty much what you are looking for, only your thread was about the block being stationary.
I've been thinking about both types for my car, since they are much less complicated than an electromechanical opening mechanism, but my diesel is almost always running cold. Today is the first day here with temps around 15*C, so maybe shortly I'll hear my fan (haven't heard it yet) and start unblocking the grill and thinking about something permanent. I really wonder how this static grill "shield" will perform. When are you going to try it?

[Piwoslaw]

Originally Posted by lunarhighway

i've also considdered a double grill, where there's two rows of vertical slats where the second row visually blocks the first but there's a space between them so the theoretical volume of air that could enter is the same.

Something like this?
2slit.jpg

[Xringer]

What you are talking about sounds like a screen mesh.
Depending on the size of the openings in the mesh, air flow slows way down at higher speeds.
During a hurricane, a screen mesh satellite dish has almost the same wind loading as a solid metal dish.

So, one could use a small aperture mesh that looks almost solid at 55 MPH
and higher, but allows air to be pulled in by the fan while in slow city traffic.


It's likely that the radiator air flow is limited by the apertures of the honeycomb.
Very high speed air rammed in the nose might just flow around it.

[winkosmosis]

Originally Posted by Xringer

What you are talking about sounds like a screen mesh.
Depending on the size of the openings in the mesh, air flow slows way down at higher speeds.
During a hurricane, a screen mesh satellite dish has almost the same wind loading as a solid metal dish.

So, one could use a small aperture mesh that looks almost solid at 55 MPH
and higher, but allows air to be pulled in by the fan while in slow city traffic.


It's likely that the radiator air flow is limited by the apertures of the honeycomb.
Very high speed air rammed in the nose might just flow around it.

I was about to post about meshes. An angled mesh can work like a plain angled surface for air to flow around, but the radiator fan can still suck through it.

[2000mc]

lunarhighway - so the problem is that you seem to get enough air while driving, but not at idle? how hot does it actually get in traffic? does the fan cycle on and off, or run constant as the temp continues to rise? are you certain the cars temps dont do the exact same thing w/o any grill block?

if the fan can run and cool ya off easy enough when stopped, i would think that everything is normal.

now i know lots of gm cars live by the airdam. for me, my 99 saturn sc1 sports a full grill block, and only gets what air bounces up off the airdam. temps didnt change at all when i blocked it, only difference was better mileage

[lunarhighway]

@Piwoslaw yup that's exactly the effect i had in mind
@Xringer i considdered mesh a while back...i think i made a post about it, i'll look it up, but what i could find on the web didn't say much about a speed related block effect, the most important thing i learend is that the air tends to travle as laminar flow (if that's the right term)... some distance beyond the mesh... but that's a different story.
@2000mc

it def isn't a bottom breather... the airflow was originally in no way forced up into the radiator... there are some holes in a support beam below and in front of the rad, but after some speculation i concluded they where structural. my undertray completely covers these and this has not changed cooling in any visible way... on the other hand these could serve as an additional intake when the fan comes on... than again at speed with the holes direcly behind the little airdam, some low pressure might actually such out air before it goes trough the rad...

i've only once had a near panic moment when a short distance from my home trafic came to a stop... the weather had been quite good that day but my full winter grillblock for the topgrill was still there and the temp would just go into the redline... fontunately shortly after that traffic resolved and i made it home, and pulled out the block....

so for now i'd like an all season block i can forget about
even if it's slightly worse in winter, being able to leave it in place in summer should mean a net improvement, or at worst the same effect without all the worries