Aero RV Belly Pan(s)

[orbywan]

Originally Posted by slowmover

Get this Hitch Step from SUPERBUMPER! Help Eliminate Rear End Collision Damage with Patented Compressor System that's Proven & Tested

Looks interesting but I've spent enough time and money on this hitch for a while.

[slowmover]

Thought you should see the idea. Nothing more. Some nice looking engineering on that hitch. Have been thinking of this thread now the weather is better. We actually had temps below 60F this morning.

[orbywan]

Originally Posted by slowmover

Thought you should see the idea. Nothing more. Some nice looking engineering on that hitch. Have been thinking of this thread now the weather is better. We actually had temps below 60F this morning.

Thanks. Yes it's starting to get nice here too. I'm dying to get this thing done and do some more testing and go enjoy this weather. Time for some more off road adventures!

[ausias]

I'm waiting for the mpg test.
Ii you tow a trailer you may compare the torque added because of the additional length. Easily 1000 N of weight in 0.4 m length (from fixation to pivot point) of the normal towing make 400Nm of torque on chasis/towing fixation.
But be aware that 1000N of weight exerted 1.2 m length will make 1200 Nm, you will need to absorve 3 times more torque in chasis/towing fixation. Some additional welding of vertical bars will be needed or you will discover, that weldings are strong enough to transmit forces and torques capable of destructing next object.
o=======x

adding a vertical force in x will tend to rotate with center in o, so flexing the tow bar.

\ .
\ .
\ .
o======x

adding a Force to x will rotate with center o only if welded reinforcements elongate sufficient to allow flexing the towing bar.


In spain a modification like yours needs an engeenering project and lots of burocracy to legallize and homologate in ITV and Miniesterio de Industria, it could be done but I suspect in USA there are differents regulations. Rear suspension will suffer also if towing a trailer means adding vertical weight to the joint. Also, lateral forces in joint will make lose sooner the stability of the rear end (that is the whole).

[orbywan]

Originally Posted by ausias

I'm waiting for the mpg test.
Ii you tow a trailer you may compare the torque added because of the additional length. Easily 1000 N of weight in 0.4 m length (from fixation to pivot point) of the normal towing make 400Nm of torque on chasis/towing fixation.
But be aware that 1000N of weight exerted 1.2 m length will make 1200 Nm, you will need to absorve 3 times more torque in chasis/towing fixation. Some additional welding of vertical bars will be needed or you will discover, that weldings are strong enough to transmit forces and torques capable of destructing next object.
o=======x

adding a vertical force in x will tend to rotate with center in o, so flexing the tow bar.

\ .
\ .
\ .
o======x

adding a Force to x will rotate with center o only if welded reinforcements elongate sufficient to allow flexing the towing bar.


In spain a modification like yours needs an engeenering project and lots of burocracy to legallize and homologate in ITV and Miniesterio de Industria, it could be done but I suspect in USA there are differents regulations. Rear suspension will suffer also if towing a trailer means adding vertical weight to the joint. Also, lateral forces in joint will make lose sooner the stability of the rear end (that is the whole).

Yes, in other words it’s a tough application, I get it. Here’s the deal. I’m in the process of figuring out to what extent you can increase the FE of RV’s using aerodynamic improvements. As we all know, in the available box of tricks, the biggest gain to be had in one shot, especially on an RV, is by adding a boat tail.

That’s exactly what I did, I added a boat tail. If early tests are accurate, the boat tail yielded easily a 25% improvement in mileage. If that turns out to be even close to the improvement the average RV owner can expect by making that modification, I suspect a lot of guys are going to be building boat tails. I don’t know what the actual percentage is, but I can tell you the majority of those thinking about embarking on those improvements are most likely going to want to still be able to tow something with their RV, all the time or once in a while.

I fall into that category which is why I built the extended hitch and why I will find out what works and what doesn’t. If I break or bend something along the way that’s called R&D. The thing is, the hitch issue has to be sorted out one way or the other so I’m in the process of sorting.

[skyking]

Looking good there. Great to use that space for storage.
I won't go that route if/when I boat tail the 5th wheel, because the combined length is already a problem so I have to be able to fold up my boat tail. Certainly not a problem on your RV, and no limit to the light stuff you can pack in there with no ill effect.

[orbywan]

Originally Posted by skyking

Looking good there. Great to use that space for storage.
I won't go that route if/when I boat tail the 5th wheel, because the combined length is already a problem so I have to be able to fold up my boat tail. Certainly not a problem on your RV, and no limit to the light stuff you can pack in there with no ill effect.

There's roughly 145 cu.ft. of space back there, and not all of it is usable, but it still adds a lot of storage space. We've taken one trip to the mountains in this configuration. I didn't have the hitch on it, which forms the base of a very sturdy floor in it now, but I loaded it with big light stuff which freed up a lot of interior space.

Once I get the hitch dialed in and arrive at a final configuration for the tail, I'll remove the original back wall of the RV and extend the interior bedroom space back another 3 or 4 feet. The bed is built on a platform about the same height as the average diesel pusher bed so when the wall is moved back we'll gain the extra length in the bedroom at that height, and gain the same length below the height of the bed in the form of storage under the bed and above the hitch superstructure.

Because the suspension is so stiff, and the vehicle fairly heavy, I think this is going to work out really well. I probably won't have a chance to test it with the boat on it until March of next year, but there will be several trips over the winter with the quad and trailer in tow. The quad and trailer probably weigh 1200 to 1500 pounds with a tonque weight of 70 or 80 pounds. If there is any serious flaws in the hitch design hopefully they will show up towing the lighter load.

Anyway, I'm looking forward to seeing some efforts by others towards fold up boat tails. That configuration will probably fit the needs of the most number of larger vehicles, i.e., trucks, RV's etc.

[ausias]

I found the translation to "coroplast" in spanish and I did find some place to buy all over Spain.
MAgic word are:
Coroplast -> "Policarbonato de doble capa" or "Policarbonato de doble hoja"

I can buy how much I want in do-it.yourself hypermarkets like "Leroy&Merlin" or other stores or construction materials dealers. It's used for roofs, greenhouse and other.

I will need a lot of square meters for making my large van underbody

Maybe the golf ball vortex generators present on Toyota Prius and Volkswagen AG cars could be done by pressing some hot rolling massage machine or anything. Or maybe i will find "dimpled panels" (other magic word)
See the video:
HowStuffWorks Videos "MythBusters: Dimpled Car MiniMyth"

[skyking]

wow, extending the interior volume. You ARE going for it!
I was thinking a nice floor, and vertical bike racks and things like that. A bigger bedroom would be a huge plus.

[skyking]

Orbywan, could I bend your ear about cameras and monitors?