Potential mpg loss % with custom aero trailer.

[redneck]

.

Just do this...

Post - 1

>

.

[redneck]

.

Post - 2

>

.

[redneck]

.

Post - 3

Etc.. Etc...





>

.

[Gschuld]

I could do that…. and I might soon enough.

I am pondering a bunch of factors that are pulling my designs in opposite directions.

Once at the track, I’d be spending 3-4 nights there. Most either bring RVs pulling a small/mid sized enclosed cargo trailer for the bikes, equipment or drive trucks/SUVs pulling a 7x14 or so cargo trailer that they sleep in when the bikes and stuff are outside under 10x10 EZ UP tents. Some use large transit vans for an all in one setup. Almost everyone has air conditioning. More than half the events are in the south. And it’s a summer sport for the most part with a few races spring and early fall.

There are a number of tracks with electric hookups available, but demand far outstrips supply and those few spots are not easy to get. So you end up with a sea of small to mid sized inverter generators running all day, and often at night if it is over 75 degrees at night.

Cargo trailers are rarely used during the day even with the AC running because there are few windows and you feel like you are in a large dark closet. At night that’s fine(ideal even)

I’d like a space that I can ideally once at the track have standing headroom(I’m 6’3”) and be set up so that it’s a pleasant place to be during the day. Some windows are key here.

My wife’s version of going to the track is to be able to spend a decent amount of the time inside, with the AC on, sitting somewhere relatively comfortable and reading a book/listening to music/using the internet, etc. A high quality HEPA/activated carbon filters combo plugged into the intake side of the AC would help greatly with the inevitable fumes in the air from the generators and race bikes running race fuel.

To accomplish this, I’d need an expandable (in height) trailer design if I am to keep the frontal area of the trailer close to the frontal area of the Jeep for highway drag reduction. Several ways to go about this, and all have their drawbacks.

From a custom HI LO design, to a front hinged roof lid that created a standing headroom at the back, and several novel designs in between.

With any of these a reasonable amount of sound and or thermal insulation is challenging at best. Some more complex than others.

Another factor is the other potential uses of the trailer when not going to the races. Perhaps some traveling, moving things locally, etc. 24/7 standing height would definitely be more ideal there.

Another factor is security. Having the ability to secure the trailer helps. Several racers have had their trailers stolen or broken into when they have stayed in motels/hotels on two day drives to and from the track. I’m hoping to avoid that situation entirely if possible.

So there are two ways:

A full standing height trailer with a design to limit the full height to the centerline portion to minimize frontal area with a tapering tail and all the other tricks to make the best aero I can muster.

1- easier to build
2- lighter weight
3- far more sound/thermal efficiency (more comfortable and makes heating/cooling simpler)
4- more useful without needing to mess with a variable shape
5- easier to secure
6- lower aero efficiency potential

And an alterable design that is low on the highway, and converts to tall at the track.

Pretty much the opposite of the above.

So if I could wave a magic wand, I’d be able to lay out several designs and be able to get Jeep/trailer CD and highway MPG numbers for each. And if the difference is small enough I’d likely go with an optimized full height design.

George

[freebeard]

Have you considered the Airstream Basecamp?

https://www.airstream.com/travel-trailers/basecamp/

Basecamp's design provides plenty of room to load and unload large gear through the 26" x 46" rear hatch. Inside, you have 126" of available cargo depth from the hatch to the galley cabinets without any obstructions in your way.

It's got taper in plan

[Gschuld]

Yes actually, I been researching and studying them a great deal. Both the 16 and 20ft versions. Not for consideration to purchase though if that what you meant.

They appear smartly designed, but as they are they would not serve my logistical needs well. They were never intended to carry two 425lb motorcycles, and I couldn’t fit them in without significant modifications. But they serve as useful examples regardless.

George

[freebeard]

https://www.flyingboxcar.com/index.php?page=2

The loading works easily with this kind of access, a truck or forklift drives right up to the edge of the cargo bay and everything fits right in. In case it's something with wheels or on tracks, we just get out the ramps and drive it in. If the cargo`s motor is dead, we just use a winch.The airplane can also be flown with the doors removed, for airdrops or the like! If a load is too long to allow the doors to be closed, sometimes it is possible to let it stick out and fly without the doors, too.

[Gschuld]

That’s a neat design. I was thinking of something like that but ever saw a actual example. It goes to show that most ideas have already been thought of and done. Thank you for the reference.

I have a limitation in my designs. To stay with a 6’ wide trailer and the wheels within that 6’, I’d need to have the front wheels of the pair of motorcycles in line with the trailer wheels, this puts a 825lb center of weight a little more than 2ft behind the trailer wheels. So my starting point is rear heavy before loading the rest. I can easily load the rest of the tools and gear fwd in the trailer down low to achieve proper 10-15% tongue weight and end up with a low center of gravity and good weight bias fwd. So only the lightest of items could go in the split tail design. And this split tail design would be most useful with a full standing height trailer of course.

George

[Piotrsko]

Back the bikes in since the rear wheel is usually heavier loaded than the front. Would move the CG forward about the 2 ft.

[Gschuld]

Actually the bikes are slightly front biased weight wise and they need to go in front first for two other reasons. One being the front wheel/forks are narrower than the rear wheel/swingarm/shocks/exhaust and I need all the spread I can get to get by the bikes between them as the front wheels/forks are up against the wheel wells of the trailer, and the handle bars are by far the widest part so with them fwd, I have a chance to taper the sides of the trailer narrower towards the rear end.

George