Making a Shape out of Fiberglass?

[Ron Earp]

or has the whole of the USA lost touch with DIY & adopted check book building...:sad:

Nope, they haven't. I've already talked to my dad about using his wood shop. Cut risers and forms just like he did for aircraft and skin it. He's actually pretty excited about doing it.

I just didn't want to go spend 15 hours making something that could be found for $75 by thinking outside the box. I didn't think of the EAA and there is one about four miles away and I know a couple of guys in there. I think they buy their canopies though, but will check it out. Cool idea, but I bet I could ruin a lot of Lexan before, if, I figured it out!!!:thumbsup:

 

[Jac Mac]

I looked on U-tube & there are several videos of guys forming canopies- just remember if you go with lexan/polycarbonate its hydroscopic & has to be dried properly before you even think about trying to form it.
I would have considered a 'Vee' nose extension in alloy over the drawbar & create a bit of extra storage space for light objects like empty fuel containers etc.. Still have a flat surface for the Solar panel that way.

 

[Ron Earp]

I would have considered a 'Vee' nose extension in alloy over the drawbar & create a bit of extra storage space for light objects like empty fuel containers etc.. Still have a flat surface for the Solar panel that way.

Hmmmmm, really easy to make. I wonder how much it'd give up on aero compared to a compound shape?

Could make a vee with three vertexes, front view:

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To more approximate the curve. Both are easily done. Slight downward slope on the top part, slight upward slope on the bottom part. Install hinged door on one of the flats, would hold the chair and umbrella nicely.

-Dang, drawing didn't work in text.

 

[Chris Huck]

I would make a form out of wood formers, shutter it with sheet ply then wack on some filler and sand to a decent finnish then take a moulding as discussed in an earlier thread, you never know you may be able to sell some to others.
As an aside, enclose a picture of 20 sheets of plywood and 50 tubs of filler and a bit of elbow grease, to be used as a buck.

 

[Jac Mac]

Something like this?

 

[Jayson]

Chris

Did you make that body?

 

[Randy V]

I would make a form out of wood formers, shutter it with sheet ply then wack on some filler and sand to a decent finnish then take a moulding as discussed in an earlier thread, you never know you may be able to sell some to others.
As an aside, enclose a picture of 20 sheets of plywood and 50 tubs of filler and a bit of elbow grease, to be used as a buck.

Welcome to GT40s!

I would like to know more about your project in this picture....

Please start up a thread in the Build Logs forum and tell us about it..
:thumbsup:

 

[Jayson]

So would I!

 

[Ron Earp]

Alright. Cut some metal into the shape I wanted, bent it, and then had a local outfit weld it for a few buck. I was going to rivet it together but the welding was a deal.

I'm going to install it this afternoon and tow to the track tomorrow. Current fuel mileage is a well-known 7.6 mpg. We'll see if this can help it at all. If not Looks like I have some ally fabrication materials in stock.

 

[Jack]

Looks nicely made Ron. Let us all know about the outstanding increase in fuel mileage!

 

[Ron Earp]

Looks nicely made Ron. Let us all know about the outstanding increase in fuel mileage!

I have a feeling there won't be any, but, it is worth a try!! If it increased a solid one mpg that would be useful to me with respect to having enough range to make it to one additional track without a refuel (180 mile range now, would increase to 204 miles). If two mpg like all of these jokers claim then it'd be fantastic!

But I'm pessimistic we'll see anything at all.

R

 

[Jack]

Me too!

 

[Ron Earp]

Well, I have about 400 miles of towing with the "cap" in place. I have accurately tracked my fuel mileage and the results are in. As near as I can tell the cap has a 0.3-0.4 mpg increase which is just about in the noise of the measurement.

Now I'm well-versed in statistics and measurement science and I realize I'll need more testing to conclusively prove effectiveness. And, as with any project V1.0 was not the best design. This cap only has a one foot rise at the peak. I think to really make one of these work it'd need around a 2-3 foot rise at the peak like Jac Mac originally drew.

But, for now it is off for some vacation - horse riding, archery, skeet/trap, mountain biking, and some hiking.

 

[Jeff Young]

Bob needs a diesel.

 

[Ron Earp]

Just to follow up with this story, there was no statistically significant increase in fuel economy as many might expect. Towing mileage is still in the 7-7.6 MPG range.

But, I did get to do a weight experiment. I recently towed the trailer without the car on it and got the same mileage, therefore, I think the issue is aero and not trailer weight.

So, I am going to redouble my efforts to make a cap for the trailer. I'll check back in with my design but I'm thinking of aluminum ribs coming off the front of the trailer at various heights and then skinning it to make a hemisphere, or more accurately, 1/2 of a cylinder when viewed from the top down.

 

[Will Campbell]

Hi Ron,

I know your trailer is open, and this comment applies more to closed trailers, so take it with a large grain of salt.

Making the nose more "roundy" may help, but the real gains will be realized when you develop the nose to help manage airflow along the sides of the trailer. When airflow separates along the sides, there is tremendous drag. This is why the traditional "wedge" nose on so many trailers is much less effective than most people imagine- it doesn't decrease frontal area (of course) but worse, it doesn't do much about managing airflow along the sides of the trailer, so the real coefficient of drag is not changed very much.

The same thing applies to the rear of the trailer- making it more of a Kamm-design would help tremendously, I think.

I only know one car trailer design that was seriously influenced by aero principles, and that is the BRE Aerovault. You can see a picture and some analysis by Pete Brock at http://www.bre2.net/mm5/merchant.mvc?Screen=PROD&Store_Code=B&Product_Code=bre2_aerovault_trailer&Category_Code=car_trailers

For your trailer and tow vehicle, I would imagine that the best results would come from managing airflow as a unit- meaning work on the bed area of the truck, coordinated with modes to the nose, as well as possibly some side "skirts" on the leading edge of the trailer. Attaching (in an aero sense) the tow vehicle to the trailer will probably yield good results, as evidenced by some OTR trucks that make an effort to do exactly that with flexible skirts connecting the rear of the tractor to the trailer.

-Will

 

[Rick Muck- Mark IV]

Ron,

Look at these Aerodynamic Fuel Economy Savers for Road Vehicles

I know several truckers who use them and some fleets have tested them and are using them. The gain would probably be small but the idea is to manage the side aero of the trailer. The open trailer is harder to "aero out" but there are some tricks that will help.

 

[Ron Earp]

I think we discussed the Aero tabs here or on another website where I posted this. What I do remember is they are expensive as hell and might be of limited use on my trailer, which looks like this:

Probably doing something with those ramps at the rear would help. But they are just so convenient to unpin and let drop on the ground. No muss no fuss.

 

[Ron Scarboro]

Making an open trailer aerodynamic is not easy. A couple of suggestions...

1. Is the white box full? Though not cheap, replacing that will something accessible from the top (over sized tool chest type of thing) that is only the height of the rear of the tailgate would help a lot.

2. Yep, the rear ramps have to go.

Cheaper and more functional than attaching a foil to the front of the trailer may be to add a camper top to the pickup. That would help keep the airflow elevated so that it doesn't brake the front of the trailer so much.

 

[Ron Scarboro]

Additionally, it isn't that uncommon to add a foil to the top of the truck. An example is below:

RV Towing Products - Wind Deflectors - IconDirect

It could be placed either on the roof of the truck or on the camper shell.