Landracing Forum
Misc Forums => NON LSR Posting => Topic started by: fredvance on April 09, 2008, 01:08:39 PM
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I am thinking of building an enclosed trailer for my bike. I want to make it as slick as possible. If I V the front will a sharp edge on the nose cut the air better than a rounded one. Fred
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Fred --
Thanks for asking the question. I don't have the answer, but'll be looking carefully at the responses. I'm in the market for a new race trailer and want to have good aero. Every time I ask an owner or a dealer I get a not-very-trustworthy answer. "Hey, the truck pulls it like the trailer isn't even there" isn't what I want to hear. What I'll believe is a report from someone telling me how many gallons of fuel he used to pull to and from Bonneville a couple of trips -- so we get a REAL performance figure.
Just this morning my ability to report like that died on me -- my PDA, which had a running fuel log of the last 120,000 miles on my pickup, went into hibernate mode and, upon rebooting, all data was lost. Dang!
Back to the trailer -- I want to know fuel consumption numbers from the various configurations of trailer, with the "tow-ability" a second question. I know that the front aero piece called a "Noze Cone" (trademarked name) helps with my big trucks -- and I therefore assume it'd make a difference on a trailer. As for the V front end -- I haven't seen any data that's reliable.
Post your comments, boys and girls, and let Fred and me see if there really is a difference. Thanks.
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I am thinking of building an enclosed trailer for my bike. I want to make it as slick as possible. If I V the front will a sharp edge on the nose cut the air better than a rounded one. Fred
If you are planning on staying "sub-sonic" I would make it rounded. A lot is going to depend on what the air is like coming off of the back of the tow vehicle.
Jon, when my dad died at 94 he still had every data log of mileage, date, gallons to fill, and location since the 20's for every car he owned. None of them ever went into hibernation or lost their data. They weren't very high tech........ a little notebook and a pencil and my mom made the entries usually :-).
c ya,
Sum
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Terry Nish has vortex generators on the race car trailer that cleans up the trailering air. I think if you look on the www.nishmotorsports.com they are listed.
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Yes, Sum, I yield the point. My '89 GMC Jimmy has a spiral notebook in the glovebox showing every maintenance, all the fuel, and so on -- since the truck was brand new. The battery has gone dead (even been removed) from the vehicle numerous times and that paper log is still accurate.
I got the PDA when the current truck was new, bought the Fuel Minder program, and thought I had the world by the tail. Then I learned that the fuel program wasn't quite as good as I had hoped, but it served well enough. I'm bummed by the loss of phone numbers and all, and for them the PDA has an advantage over paper in that it';s easy to change data without resorting to an eraser on the end of the pencil.
So -- hey, everyone, if you want me to have your phone number/address/email or whatever -- send it along in a PM or straight email to me: jonwennerberg@nancyandjon.org
Ta-ta for now.
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Jon,----the secret to most aero and especially trucks is MOVE the AIR ONCE!!!!!!!!!!! Some big rigs have BAT WINGS to enclose the joint between the truck and the trailer. Taper the rear of the trailer with a ramp and rroof and two doors that form a V and move the wheels inside. ("Wortex generators" good German term) on the rear at the transition point!!
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Glen, I've seen the vortex generators, I've talked with the folks at Nish, and I've talked to other folks that have run the generators. Nobody has shown me the hard data to prove that the things work, and like a Noze Cone, like the V front on a trailer, like all those things -- until I see some solid proof -- I don't believe it. I'm not saying they don't -- I'm saying I'm not buying a trailer with a $500 - $1,000 added front end in the hopes that it makes a difference.
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the size you need a round front shape is the right solution......a v nose make sense above 600 mph....any idea how much the speeding ticket would be for 600 mph.....
Round is fine - and if the "round" is a opening radius and goes proper tangential into the side panels you will get a clean shape.
To the Vortex.....Vortex are to break the vacuum behind the vehicle when you got too much turbulences on the rear end...in other words....bad rear end aerodynamic.......the old aerodynamic rule says...it's not important how you go into the air....it's important how you got out of the air......but if the airflow, coming from the front to the rear, is clean....it's easier to go properly out of the air.........what means....throw the Vortex into the garbage bin.........
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For whatever its worth. We'r running a 1997 GMC Suburban, that I call "da boat". We pull a 6x12 Timberwolf lowboy cycle hauler. Without the trailer & with some of my work tools, on the hwy I get 15-16 mpg. The ironic thing is, with the trailer, bike, tools, etc, I still get 15mpg so long as I keep it at 65mph. - - Go to 70mph and it dives to 13 1/2to 14. I did make up a spoiler/(vortex generator?) that we mount on the rear roof of the GMC when pulling the trailer. It seemed to save a strong 1mpg comparred to not using it. I have no "hard data" other then the mpg checks that we do on most every fill-up. OOoops, air conditioning ! I forgot, turn the air on and loose another 1 - 1 1/2. Its confounding to me though, how little difference there is with this mpg thing with trailer or with out, at least as far as "da boat" goes. Iam guessing it has to do with speed. 8-)
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For whatever its worth. We'r running a 1997 GMC Suburban, that I call "da boat". We pull a 6x12 Timberwolf lowboy cycle hauler. Without the trailer & with some of my work tools, on the hwy I get 15-16 mpg. The ironic thing is, with the trailer, bike, tools, etc, I still get 15mpg so long as I keep it at 65mph. - - Go to 70mph and it dives to 13 1/2to 14. I did make up a spoiler/(vortex generator?) that we mount on the rear roof of the GMC when pulling the trailer. It seemed to save a strong 1mpg comparred to not using it. I have no "hard data" other then the mpg checks that we do on most every fill-up. OOoops, air conditioning ! I forgot, turn the air on and loose another 1 - 1 1/2. Its confounding to me though, how little difference there is with this mpg thing with trailer or with out, at least as far as "da boat" goes. Iam guessing it has to do with speed. 8-)
"da boat" is probably pushing all of the air out of the way and it probably doesn't come together again until behind that trailer. Does the mileage go down at 70 the same with or without the trailer.
I get 20 mpg with my truck at 75 without the teardrop trailer and 16-17 with it at 75. If I'm in Calif. and running around 65 with the trailer it will go up to 18-19.
c ya,
Sum
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The diffrece in HP required for a 24' Ryder rental truck to be able to maintain 55 vs 70 will astound you; nearly a 1/3 more, and have any reserve left for passing, climbing a hill, or slight head wind.
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"the "round" is a opening radius and goes proper tangential into the side panels"
That's what I would try first. The nose is an ellipse, with the minor diameter to match the width of the trailer, and the major radius determined by the practical length between the existing trailer front and the back of your tow (at any angle - be careful).
That's the obvious side; the front-to-top can also be improved with any radius (bigger = better), especially if the distance from the tow to the trailer is too large to bridge with a cover from the tow roof.
The bottom is a puzzle, since the cd will improve with any aero contour - but do you want air passing under the trailer?
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Trucks that compete in the truck fuel millage contest have upside down nose cones in front of the trailer tandems and BELLYPANS, and Wipers on the tires to try to slow down or stop the rotational air on the tires.
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A suburban is a brick in the air.....and moving a brick faster cost mpg.....
A spoiler and a vortex are two totally different things.....a spoiler is a kind of a wing and helps a lot to get a better mpg.....a vortex are small - two by three inches - plastic shapes which people add on the end of the side panels to interupt the turbulences.......a spoiler/wing clean the airflow.......
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The diffrece in HP required for a 24' Ryder rental truck to be able to maintain 55 vs 70 will astound you; nearly a 1/3 more, and have any reserve left for passing, climbing a hill, or slight head wind.
Agreed! I drove one from Alabama to San Diego once and experienced the same thing.
Scott
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Sum, the aerodynamic of your pick up is so bad that the teardrop trailer behind improve the aerodynamic.
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The gap between the tow car and trailer is always a problem - the airflow collapse into this gap, try to go out again and produce turbulences and vacuums to the same time.
That's the reason why here in Germany short tows are very popular for truck/trailer combinations.
About the airflow under the trailer - give the air enough space that it can go through.....your never can close it so that you get an aerodynamic improvement. Important is, that the floor under the trailer is so flat as possible to create no interuption from the airflow......normally you got the axle and the "tow" pipe to the towing vehicle in this airflow. If his parts are covered, so that this aera is a smooth surface it will help to get a clean airflow.......
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A suburban is a brick in the air.....and moving a brick faster cost mpg.....
A spoiler and a vortex are two totally different things.....a spoiler is a kind of a wing and helps a lot to get a better mpg.....a vortex are small - two by three inches - plastic shapes which people add on the end of the side panels to interupt the turbulences.......a spoiler/wing clean the airflow.......
Thanks PorkPie - I did go to the Nish Motorsport web site and got educated on the difference between spoiler and vortex generator. (being a bike guy, and some what of a cyber neanderthal, Iam still educating myself with this high tech stuff.) I do think that the spoiler on the rear roof of the GMC helps. And Sumner, getting close to 20 mpg would put me in GMC heaven. To answer does the mpg drop over 70 with or without the trailer, is you betcha it does. If there are any cost effective tips you guyz may have to improve mpg with da boat, I am all ears. Thanks, all you guys and this web site are great. 8-)
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I believe the type of tow vehicle is a main factor in your milage. My 03 chevy HD2500 has an 8.1 in it . When I tow my 13000 lb 5th wheel it gets 8 mpg. When I tow the race car the milage improves to 8 mpg. Driving empty with no trailer the milage increases all the way up to 8 mpg. :-D
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OK so if I am towing with a pickup the air is not going to flow over the trailer, put a round nose v and angle the v down from the trailer body to v?? Next what about something like a mud flap in fornt of the tire to deal with the air around the tire?
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Reducing frontal area and trying to fill gaps work pretty well.
(http://i134.photobucket.com/albums/q91/autodoc/dodgeloadbar1.jpg)
without a car on the top, the mileage is good (14mpg), add a car to the top and it drops to 11. I built the top rack on the trailer close to the cab and at the same height, it really helps.
Dave
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Thundersalt: You oughta have a diesel in that HD2500 of yours. 25 mpg on the way to and from Maxton last weekend. 14 mpg towing cross-country to Bville -- trailer weight about 7,000. 19 mpg towing our old 6x12 trailer to Bonneville.
Fred: Would you mind explaining a little bit about your last post? The "round nose V" and "angle the V down" isn't as clear as it could be -- at least to me. Whaddaya mean?
Air around the tire -- might be improved by a front flap, but don't hang it down too far or it'll rip off when you try pulling over a curb. But if you don't go down far enough it won't do much for aero. You're stuck either way, I guess. But -- I like Pork Pie's advice about the underside -- I'll make sure to cover the botton surface with either weatherproofed plywood or maybe some sheet metal.
I don't know if any of youse guys pay attention to semi trailers go down the road, but at least one major national carrier is now running trailers with side skirts that stretch from just behind the drive wheels of the road tractor all the way to right in front of the trailer tires. The skirts get down to less than a foot off the ground, I believe, and probably help a bunch to keep the air smoother under there. I don't remember if that company runs it's tractors with an air dam in front, though. . .
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Hey Fred,
Back in the early 90's there was a gentleman who ran at Bonneville by the name of Ron Pruett and he ran Thunderbird. I believe him and Mike cook were in the same class??? Mike Cook also ran a Blue Thunderbird.
Any how Ron's trailer had a rounded nose on the front. I wouldnt know how to contact him, maybe Mike Coook would know?
TIA
Clay
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I just googled this and found the following. There is more as well on google. This one has diagrams and CD by type.
or try www.nosecone.com
Click on aerodynamics then open table 1
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Sorry Jon I was afraid that description was as clear as mud. I'll try again, looking at the front of the trailer it is 5' tall then it v's forward but the v is 4' tall then from front to back the v tapers to 5' in another v. Is that any better?
Fred
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Hey Slim, is that a Duramax? I just bought a new TPD race trailer yesterday so Celia won't let me get a new truck for a few more years. :-( I have a lot of customers here at the rv shop that comment on their diesel's and I get milage responses from 10 mpg to 20 mpg. So when it's time to buy I'm not sure which way to go.
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Sum, the aerodynamic of your pick up is so bad that the teardrop trailer behind improve the aerodynamic.
Hey not so loud, my truck heard that and it has feelings also 8-). It is somewhat better than when it was stock and 18 inches (1/2 meter) higher :lol: .
Sum
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........... If there are any cost effective tips you guyz may have to improve mpg with da boat, I am all ears. Thanks, all you guys and this web site are great. 8-)
Let a woman drive it. My wife always got better gas mileage than I did :lol:,
Sum
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The DIY ethic is to be admired, but a recommendation I received from a friend of mine who hauls band gear is the Excalibur Trailer. They were built here in Milwaukee at the old Excalibur plant (the Brook Stevens designed Studebaker, and later Chevy powered neo-classic roadsters) until about five years ago when they went belly-up. While he gave no statistics, he claimed it was better than his old, square trailer. Unfortunately, they are no longer being made, but there is an outfit in Iowa that took the design and ran with it. Here's the link -
http://www.oldinc.com/magseries.htm
You can even order it with flames. It sure looks slick.
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Thundersalt:
Yes, it's a Duramax, but it's an '04 LLY option. The LLY was a second-half-of-the-year model, with more HP than the early version, but quite a bit less power than the new (current) models. I was talking with a guy at Maxton this weekend -- he's got an '06 and an '08 Duramax and says he's never ever gotten anything over 20 mpg. But -- we never drive at speeds over the speed limit. This weekend we spent most of 2,400 miles on freeways posted at 65-75 mph -- and went about 63 or less the whole time. When we've gone faster -- as little as 5 mph faster -- the economy drops drastically, like a couple of mpg. And we use the cruise control as much as possible, which probably also helps get good mileage.
Keep your tires properly inflated, and also -- I run Rotella 5W40 synthetic oil, which gave me a one mpg boost instantly when I started using it a couple of years ago.
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Sumner has the answer. I built a teardrop trail for my trailering my 39 Indian Sport Scout to shows (glad I got over that period of my life) It's 9-1/2' long and 4' wide and a little over 4' tall. The roof splits in the center right where the first 4 x 8 luan panel stopped. Just seemed like a good spot. The rear deck/trunk lifts up for a complete opening. I used thinwall tubing to hold it up but I'm sure air lifts could be used. It has independant style rubber axle stubs and I use widend fiberglass Indian front fenders; 6.70 -15 tires. About a 1000# with the bike inside. I never knew ir was there when towing with my 96 Ford F-150. Ran within 1 mpg with or without it. The only thing I would have done different would be to roll under the lower front, about a 6" radii. for more aero.
Someday I'll covert it to a camping trailer to tow behind my Honda Civic HX. ...............Good Luck
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When towing my v-nose trailer I get about 3 mpg less than when using my flatbed trailer with the same load, how ever the flatbed is about 1000 lbs lighter.
I changed three of our vehicles over to synthetic oil [mobile 1] and found no difference in mpg, [we drive 75K annually] so back to Delo 400.
Just my 2ยข, Don