New hi-speed project

[BrianG]

Don't know. Depends on cash flow to get the lipos really. I'm looking at around $500-600 just for batteries.

The only thing I've done recently is re-make the servo mount. Now the brake servo isn't offset for the extra height and I added a little spot to route the ESC throttle/BEC wires so they won't ever hit rotating parts.

I am in the process of fabbing up new dirt-guards. The stock ones do not entend far enough to the sides to contain the lipos. Also, I want to make the entire undercar as covered as possible for aerodynamic reasons. So, I attempted to make new ones out of fiberglass for weight/rigidity reasons, but am not having much luck. If I make them using glass fiber cloth or matting, I need at least 6 layers before it is thick enough (~3mm) to be not flimsy. And then the weight is just as much as 1.5mm thick aluminum. Using fleece as the fiber is too heavy with just one layer. So, I'll probably just go with aluminum since it is more rigid for the weight and it doesn't need to be as thick.

The battery tray will definitely be fiberglass though because of the shape and the fact it's not conductive.

[What's_nitro?]

Have you thought about polycarbonate for the extended dirt guards? I just cut a piece and riveted it to the chassis. The wall is 20 AWG aluminum, also riveted. It is very rigid and you could always use more rivets if the batteries were really heavy.

[BrianG]

Actually, yes I did think about poly/lexan as an option. Whatever I use I plan on bending the edges for a little "kick-up", which should help stiffness. However, this tray will not be supporting any weight (I have other ideas for that), but I want stiffness to prevent flexing with the undercar air currents. It's just hard to beat aluminum for cost to weight to stiffness ratios.

[What's_nitro?]

That's true about the aluminum being "financimechanically" efficient! I had some 3mm 7075 T6 when I made that tray but I have other plans for it.

[BrianG]

Another small update since I can't afford ~6 bills for lipos right now...

Made new dirtguards. Primary goal was to cover as much of the bottom as possible to help prevent air turbulence, and to allow room to mount the gargantuan lipo pack whenever I decide to get it.

Image showing the old vs new for a comparison.



And one with them mounted on the chassis. They're not painted yet because I may be doing more work to them.

[lutach]

Looks very good.

[BrianG]

Thanks!

They're surprisingly strong for the thickness (1.6mm). I was thinking about using some additional supports for the lipo pack since they will overhang the chassis by quite a bit, but I don't know now. I'm thinking the new dirtguards coupled with the rigidity of the battery tray may be sufficient...

I'm glad I didn't use fiberglass because it would have been at least twice as heavy. The prototype guarg I made with fglass was quite a bit heavier than the Al ones and it wasn't even as big...

[suicideneil]

Feck me....

Normally Brian, the control surfaces of wings go on the trailing edge....

[lincpimp]

Looks spiffy Brian! Nice work.

I have not had much wheel time on the mbx/gtp conversion I did due to shock issues. Could you tell me how long the from and rear shcks are when extended? I was going to use revo shocks on mine, as I had a spare set of 4, and maybe fab a set of shock towers...

[BrianG]

@neil; yeah, I guess I put them on backwards eh? lol. Seriously, I was shooting to keep the air under the car (not in the car) and as streamlined as possible.

@linc: Thanks! Without measuring, the fronts look like they could be replaced with Revo shocks with not much issue, but the rears are about 50% longer and would definitely need a new shocktower. Instead of fabbing a new tower, how about just getting another front tower and putting that in back? Of course, you'd have to figure out a new body post mounting scheme...

[lincpimp]

Originally Posted by BrianG

@neil; yeah, I guess I put them on backwards eh? lol. Seriously, I was shooting to keep the air under the car (not in the car) and as streamlined as possible.

@linc: Thanks! Without measuring, the fronts look like they could be replaced with Revo shocks with not much issue, but the rears are about 50% longer and would definitely need a new shocktower. Instead of fabbing a new tower, how about just getting another front tower and putting that in back? Of course, you'd have to figure out a new body post mounting scheme...

I thought about that, but I may just make a new shock mount that bolts to the exisring shock tower. I do not see any reason that the revo shocks will not work, they have plenty of travel for an onroad car. I am wondering what springs to use. What are the softest springs for the revo? (color of the band?)

[BrianG]

Here are your options. Looks like yellow (2.6 rate).

[BrianG]

I just quickly checked a Revo shock. A fully compressed Revo shock is the same length as a front GTP shock at about half travel. When the GTP shock is fully compressed, the Revo one would bottom out and then some. You'd need to fab a new front tower to use the Revo shocks.

The back is about 40-50% longer than a Revo shock, so that won't work either without mods.

[aqwut]

Holy Cow..!! I can imagine how many Lipos you're going to have in there..... AWESOME!!

[BrianG]

The plan is for 10s ~5Ah. Something with a high discharge to drive the 1515 2.5d (kv=1650).