earlyapex

Finally, some intelligence on the board! LOL!

Gary R.

Ok, now what difference will it make to the aerodynamics of towing a V-nose if I have:

A. Open pickup truck bed
B. Flat cap or tonneau cover over the bed
C. Full raised cap level with cab roof over the bed

Hmmm?

JPhillips-998

Yeah I thought the spare tire in the box was a good idea too!

Cory M

Choice C, the full raised cap level with the cab, would be best. I don't have any equations or pretty pictures for this one but a big percentage of drag is caused by the flow separating. So if you have a cap that is even with the cab the flow will be attached all the way to the end of the truck before it separates, rather than separating just after the cab.

Actually, if you look at the first figure in the Coefficient of Drag chart I posted you can see that the drag coefficient of the prism with the base equal to the height is only 1.05, while the thin prism with the base infinitely larger than the height has a coefficient of 2.05. The flow on the thin prism separates first so it has more drag. This is probably why a lot of past Porsche racers like the 917 and the Moby Dick 935 ran a long tails at high speed tracks like Lemans.

Gary R.

Thank you Cory, my choice was "C", followd by "B", and "A" being undesireable even for maximum MPG in daily use. Thank you for the confirmation. Now I just need to find a good source for truck caps!

earlyapex

I went for a TPD trailer, which has a wedge shaped nose section. It tows very well and doesn't move when a large truck passes me. Thanks for everyone's input.

mitch236

You haven't been passed by a big enough truck! Sometimes I feel like I am getting pushed right off the road!

Bill L Seifert

I'm glad this thread came back up. I called Wally at Trailer World about getting a new trailer. Toward the end of our conversation, I brought up wedge nose trailers. He is not an aero guy, but he knows trailers very well, and is a SCCA racer.

He said there is not gas millege gain with a Wedge nose, and that large trucks blow them all over. Don't everyone jump on me, but Wally is a trailer expert, and the above is his opinion. I'm going back to an open trailer, because I am tired of dragging a barn door through the air, and getting 8 mpg.

Bill Seifert
1987 944S Race Car

kary993

I get 11 MPG using a Denali 6 litre engine pulling a v-Nose ATC 20' trailer. Pulls fine evenwith big trucks going find and handles well in the wind. It also has more storage per square foot of trailer foot print versus a non-V-nose if you use the v-nose up front. Would not ever get a non-V-nose trailer myself if I am buying an enclosed trailer!

Tom W

I picked up my 24' TPD trailer today and brought it home (150 miles). It has a 'wedge' nose (not a v-nose). On the trip out, I got 15 mpg with the truck alone and on the trip home I got 12 mpg pulling the trailer ('06 2500HD Duramax). I passed a few semi trucks and the trailer didn't even quiver. What a smooth, easy tow! And the Allison transmission is wonderful for descending long steep hills - I never even had to hit the brakes. I'll have a couple short tows next week when I pick up the car and then drive up to Sears Point next weekend and will see how it tows loaded as opposed to empty (about 7500 vs. 4000 lbs). I can't imagine a loaded trailer getting blown more than an empty one though.

earlyapex

Tom,
I'm glad you like the trailer. The TPD sure tows very easily. I'll see you at Infineon.

roadblock

My last trailer was a flat face and it is great except for the sharp turns (in a RV or a car)
thats the main reason to get a v nose / the 20ft old trailer vs 24 ft V nose to make up for the lost
room in the V - I could not use the hidden hitch torsion bar with the new V trailer so make me an offer if you get a flat front hauler -