Foamie aerodynamics.

[GPW]

Steve, I’m thinking shorter is much better too for less drag ... something even with the TV ... my Jayco is ~ 10’tall... sticks up waaay above the old pickup /camper top ... tows like a Parachute ... Serious !!! I can really tell the difference (@ gas pump) , even worse at higher speeds ... My 12’ TD towed so easily , for a while I forgot it was there... Found myself barreling down the Hwy doing 70 , towing the new trailer ... What an Idiot!!! I’ll have to watch myself with the Foamie trailer which weighs relatively nothing in trailer terms (<500lb.) For my test tow down my bumpy (off Road Challenge) dirt road , the only thing I noticed was the rattling of the HF trailer ... the pinned folding bits.. might need to just Bolt those all solid ... Noisy on the washboards ... The truck responded like there was nothing there .... confirming the ability to easily carry the recommended 500# Ballast ...

[linuxmanxxx]

Actually I believe height is the worse culprit as I've built 2 of them now almost identical weight and one 5'6" high and other 6' high and the extra 6" uses more gas to tow as they both have the same width at 6' wide so it has to be the height killing me. I tow behind an 01 supercrew 4dr f150 so I think if one stays within the vehicle width and around their tow vehicle height is the best they can hope for plus keep the weight as low as possible. I'm going to build my next one trying to hit below the 5'6" and see how that works out plus lighter than the previous 2.

[pete42]

if the golf ball dimples work so well maybe on the next foamy a few whacks with a ball-peen hammer would be in order.

prem has some chicken foot looking things on his cargo trailer that break up the air flow and he says gives him better gas mileage.

"As a result, the boundary layer resists the adverse pressure gradient much longer before it separates from the surface"
makes sense to me.

[GPW]

Steve, I believe you may just have established an optimal size ... All makes Good sense really !
Problem is all my trailers sit pretty high to begin with , so inside a 4’ is about as much cabin height as I can go and not be much over the truck (like my toy Foamie ) ... May have to try reversing the springs , with such little weight on them they may not bottom out ... but at a gain of only a few inches .. What’s the minimum height a trailer can be off the ground ??? (safely) See some folks use torsion axles which seem to be a bit lower .... no experience with those ... ?

Pete ... Hammer Longer the flow stays attached , less drag it produces in the turbulent layer which is smaller ... http://en.wikipedia.org/wiki/Wingtip_vortices

[loaderman]

I have seen pretty low car haulers

[SteveW]

My MINI's hitch is going to be pretty low, so I wanted to get the trailer as low as possible and still be safe/functional. And if that improves aerodynamics as well, I guess that's just a bonus. I see the Dexter torsion axle allows different angles. Are these angles adjustable once installed, or are they a set-it-and-leave-it kinda thing?

[wagondude]

My MINI's hitch is going to be pretty low, so I wanted to get the trailer as low as possible and still be safe/functional. And if that improves aerodynamics as well, I guess that's just a bonus. I see the Dexter torsion axle allows different angles. Are these angles adjustable once installed, or are they a set-it-and-leave-it kinda thing?

I believe once the angle is set with a Dexter, that's what you get. The arms on Flexride are slpined on the shaft and can be adjusted.

Bill

[GPW]

I may be wrong , but wasn’t it said the Torsion axles only last a certain amount of time ... ?

[linuxmanxxx]

With as little use as the tears usually get, I don't think age or life on a torsion axle would ever be an issue.

[atahoekid]

I may be wrong , but wasn’t it said the Torsion axles only last a certain amount of time ... ?

The frame I have came from a 1980's built tent trailer and the torsion axle still works well. I've jumped up and down on the platform and the axle worked nicely. I think Steve was right, for as little as they get actually used they last quite a while. I guess you could call it empirical evidence

[angib]

I may be wrong , but wasn’t it said the Torsion axles only last a certain amount of time ... ?

Yep - thirty or forty years is as much as you can expect to get from a rubber torsion axle.....

[GPW]

Well, that certainly sounds “good enough” eh !!

[mikeschn]

I may be wrong , but wasn’t it said the Torsion axles only last a certain amount of time ... ?

Yep - thirty or forty years is as much as you can expect to get from a rubber torsion axle.....

Andrew,

Are you ready to play with Sketchup?

I'm diving in this weekend. Wish me luck!

Mike...

[pete42]

I may be wrong , but wasn’t it said the Torsion axles only last a certain amount of time ... ?

30 or 40 years I don't think so, most will relax not noticeable unless you know where they should be
I have seen them so relaxed on scamps the wheel would hit the top of the wheelwell

they need to be jacked up if not used for long periods of time.
On the two scamps I owned when I stored them in my brothers barn I would jack the wheels off the ground and rest the frame on jackstands
didn't take but a few minuits and kept the rubber part of the axel new.

[GPW]

That’s Good to know eh !!! Torsion axles appear to offer less drag on the under carriage than the traditional springs and axle ... If you have a standard axle 2” thick ... the 2” X 60” = 120sq.in. , almost a square foot of profile drag from the axle alone ... probably the equivalent of removing both the rear view mirrors off your car .. You can see that every little bit of drag you save adds up quickly ... to a point , then basic aerodynamics comes into play and it’s difficult to gain any more drag savings after that ... the plane designers found that out ...