Boat tail mod to my enclosed trailer

[max_frontal_area]

Originally Posted by Braebyrn

So for the gap between the truck and trailer I am thinking of making some kind of a foam filled structure. Simular to what is on loading docks that the semi's back up into. That way when you turn it collapses when pinched and expands back to normal. Maybe fastened with velcro?

The newest boat tail made it 4500+ miles without any incidents. I even met a person that patented an inflatable boat tail. He said he followed me for a good long while and said he was surprised it didn't move at all. Glad to hear it since I can't see it.

I'll see about tuft testing it this week.

I have learned that zip ties are not to be relied on, no matter how many you use or how strong they appear to be, the proper resonant frequency will undo them like a whodini. we seem to trust in hoseclamps a lot too - mistake.
as to velcro, watched a buddy almost get decrapitated by a body come loose on a racer which was conincidentally billed as "uncrashable".
go for some permanent mechanical lock. dig your foam idea just make sure it is closed cell, open cell even if is sealed or coverd moisture will penetrate
and it will get heavy/degrade. also make sure it is UV stabilized ot the sun will
eat it...
hows is the drive, what are the mpgs like with no nosecone?

[BamZipPow]

Something to consider fer the gap...something similar to the Jetway boarding bridges at the airport.

[max_frontal_area]

Originally Posted by BamZipPow

Something to consider fer the gap...something similar to the Jetway boarding bridges at the airport.

iirc they have ripples. of course you could always market them as dynamic vortex generators. they are pretty stiff too.

[JasonG]

Originally Posted by BamZipPow

Something to consider fer the gap...something similar to the Jetway boarding bridges at the airport.

That's similar to what is used on articulated buses.
Seems some company tried this on 18 wheelers but had too many complaints about access for hitching. I guess if you're not paying for the fuel, a few extra min is a big headache
For a 1500 mile trip and you are paying for the fuel, 10-15 min is cheap.

Perhaps it could be screwed to the trailer and have snaps or thumb turns to hold it to the truck ?

[BamZipPow]

Staying with the airline theme...how about something similar to the luggage turnstiles? Multiple plates that slide as you turn...

[Braebyrn]

Good ideas. I have a roll of vinyl and a friend that has industrial sewing machines, so I may go that route. The problem I am facing is that anything that will rub up against the trailer or the truck will eventually scratch it from road debris. I like the idea of removing it, so the snaps would be great. Just like what is on my sons convertible top.

Does someone know the technical term for what I am trying to accomplish? Removing the drag caused by the gap?

[BamZipPow]

You can always put down a stick on liner so it rubs up against that instead of yer truck or trailer.

Technical term...drag elimination/reduction.

[Varn]

I have mentioned before on another thread. Zote foam. It is closed cell foam and is heat moldable and is flexible. Works best with some sort of frame under it. A glue gun works pretty well for gluing sections together. A friend of mine uses a modified tip on a soldering gun to stick them together. I wouldn't use it in frontal areas unless it was well backed up but for tail areas I bet it would work pretty well. Of course there is always coroplast. I knew a guy who enclosed his utility trailer in it and it stood up very well.

[aerohead]

Originally Posted by max_frontal_area

you will find me within a few lines of your photo, however it is that special quality or curse which has allowed me access to some pretty cool discoveries.
had i always done as i was told in school i would have missed out on some truly wonderful experiences, the times being told "you cant do that" having been top inspiration to me.

can you please dig up some similar studies, i would like to read more on the subject.

i was awarded a student edition of Microstation for some work i had done
unfortunately Cosmos CFD was not part of the suite at the time of the award that will be the first step. when i worked at Northrop University (now defunct) their 1/4 scale atomspheric windtunnel was sold to Rice university
across the street, reacquintance with it would be the next step. dunno what ever happend to the supersonic tunnel they had?

in terms of expense, groovy http://ecomodder.com/forum/showthrea...tml#post204002 was $500 which IS a lot of money to me, the embellishments to it in terms of $$ and materials shouldnt be, time however
will be more valuable.

thank you for your warning! i have been playing with and dodging wind since i was a youngster, i know it will soil your britches in one instant or try to kill you the next without even blinking.

according to your posts you've been to b-ville several times, have you missed
seeing the ducted cars while on the salt? how is it that these "non functioning ducts" allow cars which would otherwise be unsafe beyond certain vehicle specific threshholds to go as fast as their engines will propel them?

i have only been to the big lake once during a small meet, but spectated and
even competed at el mirage many times - during which times i have seen several ducted cars. one owner told me when i asked what this thing was sticking through the middle of his car: "it is a vent. nose lifts at 120."
he got spanked for using it, lost his "stock" status and was bumped up into the next higher (speed) class.
then he said "but i don't care cause i get to run my baby. we have been over 150 and at times the only thing that shakes - is her ass"

Black magic? compettitors psychology?
i dont think so.

m,f,a,,I found your other post on the ducting and I'll post some material references for you this Saturday.
With respect to Bonneville,the only 'ducted' car I've seen ( and I've not seen a fraction of what's out there) was one of the Studebakers with the tubes running from behind the backlight to under the car in an attempt to spoil lift.
As far as doing this for drag reduction,at the tail end of Race Car Engineering and Aerodynamics,by Paul von Valkenburg,an ex-GM engineer,he gets into suction/ducting,and I think the reference is from J.J.Cornish III' work in this area.While 'passive' ducting can cause counterflow,with the air actually moving rear-to-front,a 'pump' can be used to suction the boundary layer and expell to the wake for a definite drag reduction.
The hitch so far,is that it requires more energy to run the pump as is recovered in drag reduction,so you end up with a net loss.
Your logic is not ill-founded,it's just that so far,no one's been able to pull it off.And this is big-dogs with deep pockets,big labs,and extreme motivation to make it work.

[aerohead]

Originally Posted by Braebyrn

So for the gap between the truck and trailer I am thinking of making some kind of a foam filled structure. Simular to what is on loading docks that the semi's back up into. That way when you turn it collapses when pinched and expands back to normal. Maybe fastened with velcro?

The newest boat tail made it 4500+ miles without any incidents. I even met a person that patented an inflatable boat tail. He said he followed me for a good long while and said he was surprised it didn't move at all. Glad to hear it since I can't see it.

I'll see about tuft testing it this week.

There's probably hundreds of good solutions to the problem.And the 'foam; approach is as valid as any.
I'm doing rigid,hinged panels,but maybe each member who's willing,could take another path and then we can weigh out the merits of each design.
Since the 'filler' is only needed going straight down the road,it itself could be an inflated structure which deflates for urban warfare.
Perhaps up at Green Bay,Wisconsin they have inflated 'Cheese-head' yard displays you could adapt between truck and trailer.( Kidding!)