Toxic_G

Ok, I am building an RC Stryker type APC from scratch. A six wheeled terrain crawler, the front set of wheels will have suspension along with the rear set. The middle set will be fixed. I want to get the front and rear set of wheels to be powered but idk know how. I know what i want to use for my radio gear and batt but i just need to know what i need for the steering and motors. I need some powerful servos and motors to make my dream truck come true.
My first plan is just doen on microsoft paint, later i will draw it I can build the chassis to what i want it to look like and i can waterproof it too. I just need help with the other equipment and setup. It doesnt need to go fast, just a moderate speed and high torque. I want it to have almost the same capabilities as the Crusher Unmanned Combat Vehicle. The concept of my drawing is the same type that the crusher is based on.
Any ideas?
Thanks

calvino

why not use 3 seperate "motor units" its much easier to do, just drop them in.... just a thought, or, modify an existing car platform with an extra differential and other parts, if you can post some specs maybe i could explain my ideas better with google sketchup (if you have it PM me), sounds like a cool idea [8D]

hands without shadows

For all the Americans, Stryker = LAV-25.

Do you want independant suspension or solid axles? With solid axles its easy to make a "through" axle. By through axle I mean something like the outside axles in this pic:


They have an input shaft and an output shaft. You hook up power to the input and you can simply run a shaft from the output to another axle. This pic doesnt show it but there are steerable hubs on the end of axles when fully assembled. Strykers are independant suspension but solid axles would be easier to setup.

How many wheels do you want? Real strykers have 8 and I think it would look better than 6. Also decide on wheel spacing, a 6x6 would have a space between the front steering axle and the rear two axles. An 8x8 would have a space between the front two steering axles and the rear two axles. Also consider how many axles you want to be steering axles. Real 8x8 Strykers have two front steering axles. A 6x6 would usually have a single front steering axle. With even axle spacing like in your pic you would want the front and rear axle to steer.

Typical 6x6 with single steering axle, notice space between front axle and rear axles:


6x6 with even wheel spacing, front and rear steering axles:


8x8 Stryker, two front steering axles with space between front axles and rear axles:


Are you sure you only want front and rear wheel drive? All wheel drive is the way to go if you actually want to go offroad and drive it a little. Real Strykers are all wheel drive

Check out RC sites that have scale sections like www.rccrawler.com www.scale4x4rc.org and www.rcmt.net These sites have more knowledgeable members when it comes to scale and scratch builds than this forum's members.

Toxic_G

6 wheel AWD with even spacing and independant suspension. OR What if there was solid axles attached to a boogie suspension whatever its called when its all connected but can "tilt" to climb. The front and rear steering axles is exactly what I want, and there needs to be some more spacing in my pic. [link]http://www.greathobbies.com/productinfo/?prod_id=TRX5605[/link] is the best looking to be upgraded for my design . Also I specifically want electric power. And something more cheaper. $300 is the ideal price I'm looking for. The 3 spearate motor mounts are a great idea. The thing is I want some thing that can be upgraded to be amphibious or at least have some water capabilities. It rains here a lot and I live by some creeks. Like I said earlier I also want good speed but lots of torque to climb obstacles. (not specifically a rock crawler though.)
I only have been using the small street cars with the single mini servo for steering, and some simple hop up gears. I have no experience with scratch built or larger models. This is my challenge for this year and the next. My pics wheels need to be bigger but thats the suspention type that I want. (sorry for all the "want"s)
Anyone is welcome to help me with this build, I really do need the help.
Might be too early to ask but spare parts will make this project go much easier. Lol. Just a thought.

Toxic_G

The shocks are behind the wheels Jsut the way teh paint program works sorry.

Mufasa_719

Man this takes me back. I was with the 1st Light armored battilion In the USMC. LAVs were my home for 4 yrs

Toxic_G

Ok those solid axles are perfect as long as I get some suspension to the front. And the best way would be to have the front wheels as the steering axle spaced from the rear two. The chassis will be from sheet alluminum, and the power could be either AWD or just the rear set of wheels I got the eight wheel design going on because it does look cooler. I got a prototype pic aswell. Now where can I get some solid axles? My hobby shop doesnt sell them, my yamaha dealership might because they have all the nessicary parts for rc cars and what-not. I'll try that later. But the problem is the rest of the components. I plan to make a template net for the body in the next two days. My axles and wheels will be handled by yamaha, leaving the motors, gearboxes, power systems and servos.
Thanks

hands without shadows

A popular transmission for scale builds at the time is the Axial AX-10 transmission. It small, strong, and available as a complete assembled transmission for $50-ish. You would only need one. A 540 size motor anywhere from 35 turns to 75 turns would be enough to move you around and do a bit of crawling. I would use a 35t-45t because anything more makes for a pretty slow rig. These motors run around $20-ish.
[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLYV2&P=7]35t[/link] [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLYV3&P=7]45t[/link] [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXKUG5&P=7]55t[/link] [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLYV4&P=7]65t[/link] [link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXNPD9&P=7]75t[/link]

The motor is connected to a speed controller (ESC). These motors are very low amp draw so basically any 540 speed controller will work. The speed controller plugs into a receiver and a battery. The speed controller has a built in voltage regulator that provides a steady 5 volts to the receiver and servos regardless of the batteries voltage. That voltage regulator is called a BEC. BEC's are rated in amps, if you are using basic servos you should have at least .75 amps of BEC for every servo. More powerfull servos draw more amps. Lights and accesories like that powered by the receiver also use power. The more amps your BEC is the better. If you are going to be using a servo on each steering axle, a servo to open doors or move a turret or something, offroad lights, and a sound system it will be better to buy a basic ESC and an external BEC to supply power to the servos, lights, and sound. ESCs range anywhere from $50-$200+.

Most solid axles are used by crawlers so there are plenty of mods to fit a servo directly onto the axle which greatly simplifies setting up your steering. If you want to go the scale route you can mount your servo (s) inside the chassis and connect them to the knuckles with links but you will have to acount for bump steer.

If you are only going to use rear 4 wheel drive you might be able to get away with placing the transmission between those axles and not having a "through" axle, depending on how close the axles are spaced. Otherwise you will have to make "through" axles which is basically taking an axle, removing the rear axle case half, and replacing it with a front axle case half and pinion gear. Its a pretty basic mod that needs minimal modification.

The most common solid axles out right now are probably the Axial AX-10 axles which run for $50-ish an axle on E-bay. Also look for HPI Wheely King axles (which are pretty wide) and Tamiya TLT axles (which are nice and narrow, perfect for scale builds). Any three of these axles will work with 2.2 wheels. I wouldnt run anything but the TLT axle with 1.9 wheels. The sizes are the wheel's (not tire's) diameter in inches just to give you a feel for size. If you want to go bigger there are other axles out there.

Toxic_G

Ok the eightwheeled platform would be a little tricky so back to the six wheeled crawler type.

calvino

just currious why not "join" 2 wheelie kings like i told you in the e-mails, that may work better because they are pre-made, and the job is much easier, just get 2 RTR's, keep the radio from one, and stick them "back to back" and find a way to reverse the other servo, and there we have it, just a thought [8D]

hands without shadows

That would work. You could do the same thing with two AX10's or two TLT's too. There are axle servo mounts available for each of these axles so it would be easy to make whichever axle you want steer.

Access

I might have got some pics of something similar at the AUVSI show. Do you want me to try to dig them up? It was independent on all 6 wheels though, it's like they took an E-maxx and added an extra set of arms of something similar.

Toxic_G

Yeah, sure that sounds cool, will probasbly help too.

Toxic_G

Guess whos getting a new Traxxas Slash? Its a sweet pro truck like the real Pro2's used in the CORR (Championship Off Road Racing) #25 Mark Jenkins or #47 Mike Jenkins. I had no idea until this morning!

Access

Okay, here you go, though I don't think they will help too much, you couldn't really see the insides of the thing.

Toxic_G

Yeah but it will help me with my robotics (thw whole point of my rc trucks) anyway thats close to what i want to build
thanks

Access

The way he described it that vehicle was designed to be one of many (hundreds or more), they would operate in an area semi- or near-autonomously and be used for scouting / security function.

He posted above about joining some wheelie kings, that seems like a good idea. Join two together and you have an 8-wheel vehicle, mod the rear one to make it rear-steering and you have front-and-rear-wheel steering. You'd have a solid-axle suspension on each set of wheels, all-wheel drive and all that other good stuff.

Toxic_G

Yep but I planned to use about $300 for it and with two wheely kings thats like $550. So I might want to save up soem more money before I go eight wheels. But other than that, yeah it is an awesome idea. Just budgeting problems.

Krazy Chicken

why not use clod axles?

Toxic_G

Like these?

hands without shadows

Clod axles are like that, but those are Gmade axles. Here are some Clod axles:

Toxic_G

I think those would work perfectly.

Toxic_G

Is there enough room for servo mounting?

hands without shadows

Yes there is. These are a size up from Wheely King, AX10, and TLT axles and work well with 6"-ish tires. I cant remember the width off the top of my head but its over 13" from outside of wheel to outside of wheel.

Toxic_G

I am laughing very hard at the size that the LAV is going to be.