High speed G-maxx for ISC event, 100mph or bust

[A RC Dude]

Originally Posted by _paralyzed_

It seems to me the biggest problem at high speeds is the body acting like a parachute and the truck lifting, jze always ran no body. You can seal the edges of the body but the wheelwells will always be taking in huge amounts of air.

My thinking is that the body needs to be as "aerodynamically transparent" as possible. Basically a swiss cheese body. So the air doesn't get "caught' under the body. Once testing begins if you could sacrifice a body to try it could make a difference.

I really think they only lift at speed because of the body, they don't seem to lift bodyless.

Just thinking out loud.......

maybe drill a lot of holes in only the rear to let air out and try mto maybe cover up some of the wheel wells up to keep as much air from getting in?

[Rivermaxx]

A swiss cheese body is definatly a big NO! I want to reduce drag not increase it. A body is a must! aerodynamic is key and if I run without a body it will shed about 10 mph off my speed atleast. I know where you going with it though. Your thinking I am going to have the same problem as jzemaxx with the truck taking off because of the body catching air. For one thing my body is definatly more aerodynamic and it sits way lower to the ground the hood is more sloped creating necessary down force . A couple things I am thinking about doing doing to prevent blow over that I know work is: The back of the body will be probably cut out allowing any air that sucked up by the fenders to escape out the back. It also will create a low pressure and help keep the car planted. I plan to run a little rake in the suspension also to create more frontal downforce. Batts are being push as far forward as possible. Thinking about making a front splitter(kinda like a front wing) out of a foam bumper. I also plan on taping the sides of the body to the bottom of the chassis with heavy duty clear packing tape, its amazing they line up perfect.

A little update I just put all new avid bearings in the carriers and new ceramic bearing throughout the transmission. I also put graphite dry lube in the cvds with boots and pillow ball socket also. I set all the pillowballs perfect by measurement and adjusted all of my toe in perfect, check and double checked.

[_paralyzed_]

well, it's a rock and a hardplace. no body= no lift, so you don't need the downforce the body creates. Add the body, you have lift and need the downforce. Of course rules dictate that the body be on.

I really think it would be worth a try once you get to testing to a/b a body with/without holes and see what happens.

I also envision an indy car style front wing that is as wide as the trucks wheels. That'd be awesome.

[JThiessen]

Just figure out how to slow down the air going over the top of the body, without causing additional drag, and you will get rid of the lift effect (bernoulies principle).

Aerodynamics is a tricky thing - there's a reason automotive and racing companies spend a fortune in wind tunnels.

Here's a thought - most leaf blowers can flow about 100mph - use one to try different things. Use a stationary video camera to record the various configurations. Maybe even get a buddy to bring theirs over so you can get more volume. Got any old smoke bombs laying around - glue some of those to the ground in front of the truck to create smoke to help see the air.

[Rivermaxx]

I am wanting to say that when jzemaxx fliped he was possible giving more throttle so it might of wheelied causing the blow over. I could be wrong but running 12s the throttle has to be more touchy than on 6s.
I will definatly run it without a body and see how it does. You are right on with the rules you must have a body so there is really no way around it. Must have a body with frontal down force period. With the price of bodies I am not going to buy one just to cut up. I am allready pushing the expense envelope with this build buying parts and extra parts for spares. Besides think about a topfuel funny car they have no holes in the body at all but the back of the body doesnt cover the rear of the wheels.This is the same idea I am having besides if you read the 91.2 mph revo thread again he did the same thing and it worked perfect. The front wing idea is called a splitter I just have to figure it out somehow.
LOL no homemade wind tunnels if it work it works if not oh well. I put a goal of 100mph because it just a goal and somthing to strive for. If it does 80mph I will be happy remember my first goal is to break the current 72.8 mph official record held by a hpi wheely king on buggy tires.

[JThiessen]

Originally Posted by Rivermaxx

The front wing idea is called a splitter I just have to figure it out somehow.

No, a wing and a splitter are two completely different animals. A wing controls air flow, a splitter essentially stops it and holds it (which is how it makes downforce). So your downforce is completely on the nose of the vehicle, rather than spread over the hood and/or roof line. If you want to use a splitter style, be prepared to raise your wing up and/or increase its angle to catch more air. Hopefully you wont end up with too much downforce - that will kill speed also.

[Rivermaxx]

What I meant to say I was thinking making a front bumper kinda like a combo bumper splitter shaped like a wing to help direct airflow up and over and around the outside of the tires. Kinda like this but shaped better.

Hard to believe this is the record holder. but it is 72.9 mph talk about Isnt that a 10th scale esc and motor? but it is from 2007.

[_paralyzed_]

Funny that the record holder is ineligible under current rules, but good for the sport that the rules are now there.

I just have this nagging feeling that your setup sans splitter and wing(even less weight) with a swiss cheese body would outperform a normal body with the splitter and wing. I think a monster truck needs a wing about as much as a rice rocket with coffee can exhaust


This thread is going well, but just to clarify I'm not arguing or trying to change your mind, just brainstorming in text. I want to see you break 100 and be able to tell my friends I talk with the owner of the worlds fastest monster truck online! Simple joys for me nowadays!

[jzemaxx]

Originally Posted by Rivermaxx

What I meant to say I was thinking making a front bumper kinda like a combo bumper splitter shaped like a wing to help direct airflow up and over and around the outside of the tires. Kinda like this but shaped better.

Hard to believe this is the record holder. but it is 72.9 mph talk about Isnt that a 10th scale esc and motor? but it is from 2007.

He was discredited later for running foams and essentially a touring car body. The next guy behind him was a 3906 emaxx that went 70.1mph. He was on this board for a while. Twin 6XL's I believe on 5S. His name is JohnnyMax

[jzemaxx]

Video of one of his passes

http://www.youtube.com/watch?v=cK7J1w4TYfA

Also the rules I went by are from the WFRCCC

[jzemaxx]

Rules from the last time they held the event.....

So, for the 2008 Challenge, any vehicle looking for a shot at the fastest MT title will have to meet the following citeria:

Tire size: Tires must have a minimum 130mm diameter and 70mm width. Foam tires are NOT allowed. There is no rule regarding sidewall height.

Body type: Any body type that can be identified as a truck (stadium, pickup or SUV) is permitted. The wheels must be OUTSIDE the body, not tucked into fender wells or skirted.


Total car length less than 40 inches, wheel-power only (no rockets or jets), and the car must have some sort of body with a "cockpit" area so it looks like it could have a driver. That's it!

[Rivermaxx]

Why wouldnt he be legal harold ? I dont really see anything wrong with it. Swiss cheese ain't going to cut it harold LOL. I dont mind anybodies ideas, my brain is tacked out trying to figure out what I need to get and what to do next. I have had the flue all this week so I started working on the truck again today. I am going to do some testing with out a wing but I might need the verticle uprights for high speed stability. OverrevO said the modified wing actually helps stabilize the car at speed. So I am sure it would help.

[_paralyzed_]

his wheels were inside the body IIRC and I thought they made some rules about tire size that would make it ineligible. You're making me question myself now, I'm going to have to re-read the rules!

edit: re read the rules and I'm confused. I thought there was a specific monster truck class with MT rules. I thought I also read about a seperate speed challenge elsewhere. I think I'm getting the two confused. My bad!

[Rivermaxx]

You know what the wheels do need to be outside the body but I never did see a pic of that truck with a body on so I dont know. They use to have a separate MT class now its just an open wheel class. Not really fair because I will be competing against buggies and any open wheels car.

[Rivermaxx]

Whats funny is that emaxx had buggy tires on the front, 2 wheel drive and ran a lamborghini body also. So whats really the difference. Neither one is really a monster truck anymore. As we all know foam tires are needed only way too achieve speeds in excess of 80mph. Unless you run taped and wraped phaltlines. The whole thing with the body is there is no real back or tailgate area its wide open, so I really dont think it will be a problem with the parachute effect.covering up the wheel wheel with clear packing tape might help.