Caravan (camper trailer) spoiler (deflector on tow vehicle roof)

[kurzer]

what do u think? will it be better?
the flow over the top seems to be better, dosn´t it?

http://imageshack.us/photo/my-images/821/aeroqek.jpg

[MetroMPG]

Yes, deflectors ahead of trailers are known to improve aerodynamics, particularly if the "face" of the trailer is badly designed.




More images: https://www.google.ca/search?q=defle...&aq=f&aqi=&aql

A deflector is going to be sensitive to size & positioning though. (Sorry I can't help there, but I bet other members here may chime in with info.)

[kurzer]

thanks for the infos.

i have tried some diffent shapes in the flow illustrator and already builded a prototype based on a roof rack. this thing will be tested asap, but i´m looking for some opinions to the FI shots.
the big deflector in the pic is overkill for my car and camper, i guess.

[aerohead]

Originally Posted by kurzer

what do u think? will it be better?
the flow over the top seems to be better, dosn´t it?

The Hyundai is to be the tow vehicle? If it has an on-board trip computer with instantaneous display,it would help you 'dial-in' a proper size,shape,and orientation for the fairing.You'd know almost immediately what your results were from each 'design' iteration.
If your computer simulation is for two-dimensional flow of the vehicle centerline it may not accurately predict the three-dimensional flow you'll actually experience.

[kurzer]

of course not. unfortunately the santamo (the towing car) hasn´t any kind of display nor a obd plug to conect a scangauge. i hope to manage a downhill test, to work out the differences.

[euromodder]

Fill in the gap between towing vehicle and trailer with a fence plate down the centerline of the trailer.

This works like the closed tailgate of a pick-up, just on its side.

[kurzer]

the prototype failed in the test and the project is finished.

the downhill sektion is not steep and long enough for good results, but the tendency was obvious.

aabbbaa

1:25,1/1:22,3
1:28,4/1:20,2/1:20,6
1:27,1/1:21,3

so i went over to a highspeed coastdown test, from 80km/h to a fixpoint with a strong front wind.

aabb

41,8/39,6
39,1/39,3

since it doesn´t work, i learned a lot about doing a proper aero testing in my region. at least...

[Iexpedite]

Just for clarification...you did all testing with the trailer attached? I was unable to see your work. For some reason the picture would not load. If testing was done without a trailer the true savings would not be indicated.

[kurzer]

of coures the trailer was attached.

maybe this link will do...

http://desmond.imageshack.us/Himg821...pg&res=landing

[KamperBob]

Hi kurzer,

To the extent I grocked your posts I think you established an envelope of measurement error. That is practical and useful for assessing results.

About your rig, in side profile the leading edge of the roof does not look terrible. I would not expect huge splash effect of bow wave. Thus, not huge benefit from a roof deflector. But I am also made considerable mental leaps based on one pic.


Pix of the actual rig might help us understand your application better. I am particularly interested on top view profile. You have one top but two sides.

If you have not already done so, look up Hucho's compilation of research by others on vehicle aero. The section of caravans is particularly good!

Cheers
Bob