Aerodynamics with flatbed

[1971ford]

I was thinking... would a flatbed improve a bumpsides aerodynamics or no?
I know mythbusters showed that driving with the tailgate down hurts your gas mileage, because of a wind tornado deal in the bed but what about no bed, just a flat bed.

It's hard to guess without putting a flatbed truck in a wind tunnel. I dont think the wind tornado would form..

[basketcase0302]

Ryan,
You're absolutely right as far as I'm concerned. This was one of my goals when building BC #16 and I'm happy with the results, (I do get 14 MPG at highway speeds @ 55MPH in BC #16 with my "little 302 and baby C-6" with 4.10 gearing).

I can also say this about my two previous dents with rear sliding glass windows:
At highway speeds / rear slider open / BC #16 has about half the draft coming through the rear sliding glass window! I have more "negative air pressure" rather than "positive air pressure" via my rear slider now.
My previous dents with a rear slider would blow a hat off of your head when the rear slider was open. Just the opposite can be said of BC #16 now.

I think you're onto something here!
Now if we can just get a few bumps into a wind tunnel!

[Caseys71]

, In theory it does seem like a flat-bed would help improve aerodynamics of a bump. Jeff's testimony seems to be pointing in that direction, it definitely would be neat to have some bumps in a wind-tunnel and compare the aerodynamics of one with a regular bed vs. that of a flat-bed. However something else you may want to consider would be that if you build one out of steel it will probably be pretty heavy, not sure that it would totally cancel out the effects of the improved aerodynamics of the flat-bed but it wouldn't help your gas mileage to have a steel flat-bed. However an aluminum flat-bed like Jeff's got on BC seems like you'd have the best of both worlds (light weight and aerodynamic).

[1971ford]

Sounds like it's decided that a wind tunnel is needed... where do i find one of those

Casey, a typical steel flatbed weighs less of a 8 foot original bed with tailgate.

I will be using ideas from 3 flatbeds pictured below. The first picture is Dustin's '71 he sold and that's the flatbed that weighed less than a typical box but I'll be slightly heavier with the addition of a few tubes.

[averagef250]

In addition to what we spoke about regarding your flatbed, I liked the wood sides that pulled off in seconds leaving a flat deck. I had intentions of adding underbed boxes in front of the rear wheels, but it I had always intended to sell that truck so putting the work in the boxes wasn't justified.

I don't know what that white truck is with the tubular bed, but to me it's pretty stupid. Everything that's mounted to the top of that bed could easily go underneath it except maybe the two spares. I would have mounted the two spares sideways against the cab to make the most use of the bed area.

The fuel tank on the gray chevy flatbed is also strange to me. There's plenty of room under the flatbed forward of the rear axle on any pickup. You can easily put 100 gallons under the flatbed up there if you build your own tank and then you can keep your 8' bed. I've seen dual purpose flatbeds built that looked like any other flatbed, but were actually 700+ gallon baffled tanks for hauling things on the road they possibly didn't want the law to know about.

[1971ford]

I do want to hold as much fuel as i can, as i will be towing the race truck 420 miles one-way to nevada and most likely it will be towed to san diego, 550 miles away. I want to stop at gas stations as little as possible because who enjoys gassing up with a big flatbed behind you.
I plan on running the 22gallon mustang tank behind the rear axle, and a tank on each side in front of the rear wheels. I dont know how much the stock saddle tanks held but it should be about the same as those, so i should hopefully have about 70 gallons on board with all 3 tanks. Id like to have a toolbox in front of one of the rear wheels but gas is priority.
The first picture (you're old truck) I'll probably be taking the idea of basic headache rack design.
Second picture i was looking at the back piece of the flatbed although i'm not sure on that.
Do you have a picture of the back of the '71 before you sold it, Dustin?
3rd picture I was looking i included before i thought as to what specifically i'd take ideas from and now that i look at it, i dont think i'll be using similar ideas. I do like the extra tire room for up travel during flex but that shouldn't be much of an issue if I have a decent ride height, and I won't be flexing too much as the truck is going ton be a tow vehicle and rear springs will remain stiff.

[averagef250]

I don't have any pictures from the rear. This picture shows some of the rear of the bed from the front. The rear panel was just 1/8" diamond plate, not reinforced. The rear lights were two 2X6 lights at an angle That flatbed was on a 90's Cummins dodge I bought for parts and traded hands between friends and I, going on 3 other trucks before I put it on the '71. It looked sharp, but wasn't the toughest thing out there. I bet the frame was only .080" wall 2x3 tubing. It really didn't need to be much thicker, it handled weight fine. Countless 1500 pound diesel engines and 9 yards of quickcrete one yard at a time when I expanded my shop.

[1971ford]

Thanks for the info. I never haul anything extremely heavy so a i wouldn't mind trading heavy weight hauling capacity for a lighter bed. Heaviest I have ever hauled is 800 pounds.
Are those 33's?

[averagef250]

35X12.50 16.5 BFG's on 10" 589/058's

[fordman]

the aerodynamics arent going to help with fuel savings i dont think. a flatbed is made more to haul larger itmes that wont fit as well in a regular bed. and is better for loading and unloading of your shipment. hay bales etc. a flat bed would be good for mounting a larger fuel tank onto the back of for fueling up other vehicles or it could be used for dual purposes. running the truck and for fueling other vehicles. once you hook up to the race truck though with a trailer or whatever you are going to use gas liek crazy. the best ways to tow your truck is to get a enclosed trailer it can fit in. to help with the wind resistance against your towed vehicle. which now leads to the next level. getting a larger truck to pull the larger trailer to put the race truck in. look around at what every one else with race trucks is doing. they may have large enclosed trailers with larger trucks i dont know. there is alot more i coul dgo into. such as what fuel are yo urunning in the race truck when it coems to racing? are you running pump fuel or race fuel? if race fuel then you are also hauling even more weight now. plus tools plus spares and spare parts. professional racers haul all of this stuff with them. they are prepared fo rthese races and do everything they cna to be prepared so they have a better chance at winning the races.

[1971ford]

35X12.50 16.5 BFG's on 10" 589/058's

They look great. I couldn't tell if they were 33's or 35's, for some reason i thought they didn't look big enough to be 35's.
I can't decided which i want to run, I would like to run 35's but I think 33's would be better for towing.

the aerodynamics arent going to help with fuel savings i dont think. a flatbed is made more to haul larger itmes that wont fit as well in a regular bed. and is better for loading and unloading of your shipment. hay bales etc. a flat bed would be good for mounting a larger fuel tank onto the back of for fueling up other vehicles or it could be used for dual purposes. running the truck and for fueling other vehicles. once you hook up to the race truck though with a trailer or whatever you are going to use gas liek crazy. the best ways to tow your truck is to get a enclosed trailer it can fit in. to help with the wind resistance against your towed vehicle. which now leads to the next level. getting a larger truck to pull the larger trailer to put the race truck in. look around at what every one else with race trucks is doing. they may have large enclosed trailers with larger trucks i dont know. there is alot more i coul dgo into. such as what fuel are yo urunning in the race truck when it coems to racing? are you running pump fuel or race fuel? if race fuel then you are also hauling even more weight now. plus tools plus spares and spare parts. professional racers haul all of this stuff with them. they are prepared fo rthese races and do everything they cna to be prepared so they have a better chance at winning the races.

After reading numerous threads and gathering information in a couple threads i have posted in the past, my 69 f250 4x4 with 390/np435/4.10's will be more than enough to tow the 8,000 pound trailer to the races, just won't be making any passes on the grades. Also, not looking to buy a enclosed car trailer. Not only would i never have the money for one (or want to put the money towards it even if i did) but i would have no where to store it, and it would pay itself off fuel savings-wise after i'm guessing more years than i'll even be alive for. I know my milage will be something like 5 while towing, but it is only going to tow 3 times a year and will be 99% town driven. Just thinking of how a flatbed may raise the mpg by 1 or lower it by 1.
Race truck runs on pump gas. The only things the highboy will be towing is a 270 pound dirtbike, 1,700lb trailer, and 5,500lb race truck.
Other vehicles will be hauling crates of spare parts and everything else. Tools are covered by the race teams we go with.
So not counting the truck itself it will be towing an estimated 7,500. Figure I'll throw random stuff in and it will come out to 8,000.