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.

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.

http://i52.photobucket.com/albums/g4...d/DSC00084.jpg

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.

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.

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.

http://scriptasylum.com/forumpics/ultra_gtp_7.jpg

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

http://scriptasylum.com/forumpics/ultra_gtp_8.jpg

Looks very good.

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...

Feck me....

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

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...

@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?)

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

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.

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

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

These
 

I would guess you need something like the Thunderpower 10S/5K/V2 packs with 25C continuous, and 50C burst output, for $549 a piece. WOW that is some power, but at a huge price. The chassis is looking good BG. It does look kind of freaky being so wide, but with the right aerodynamics and some down force wings installed that thing should move pretty quickly and hopefully stay on the ground. It will probably do very well if you can get some ground skirting to keep the air out from under the vehicle. Good work BG and good luck.

Do 12S Brian... . go go go.... 12S1P 6000mAH 25C would be just Wicked...

Kong Power and Air Thunder are somewhat cheap compared to TP and FT. You can even use the small capacity packs and I can assure you they will deliver 120A spikes when needed. I have proof :lol:.

lol, 12s is a bit much. I test-fitted two of my 14-cell NiMH packs for weight/size, and it's a bit unbalanced. And I would need to dial in tons of shock preload. 28 NiMH cells is roughly the same weight as a 12s/5Ah pack weight-wise. Besides, that would be spinning my 1515 Neu to over 73k rpm! :oh:

As far as lipo price, I would need 10s @ ~5Ah, which would be ~$600. But I have ideas to keep it well under $600.

How about moving the brake servo to the other side?

Yes, that would work, but still have the issue about the weight and over-revving of the motor. Besides, I don't wanna make yet another servo tray. :smile:

Brian, I totally forgot about the motor you're using. My fault. If you are really going to try and make it to 100mph and if you ever do get 12S lipos, I'll be more than happy to lend you my 1521/1.5Y, but you must return it as soon as you are done :yes:.

I'll keep that in mind... IF I ever get this done and IF the car survives the first few runs. :smile:

But, you really must more clearly define "you must return it as soon as you are done", because "when I'm done" could be a very, very, very long time. :wink:

I guess that I will fab up some top mounts that will place the shock in the correct location. I want a bit of downtravel, I will setup the car to ride with the driveshafts parallel with the ground. At least this way I can retain the stock shock tower and just add a mount... hope it is that easy!

I meant to say when you are done with the speed runs :lol:. You will survive the first few runs for sure. Those 1/8 scale cars are tough.

Looks awesome. What rpm are you shooting for to turn the motor?? What KV is that 1515?

Thanks!

Kv=1700. Running 10s, rpms are ~62k, but the amp draw will lower the kv and the drag won't let the motor spin that fast, so I am thinking it will actually only be going ~57k.

That will be plenty of RPM's then.

Does anyone use a Spektrum DX3/3.0 and HV-110 in your setup?

I'm curious how to set up the controller and radio so they work together; things like EPA, trim, etc. I got CH3 mixing for the rbake working on my setup, but the ESC does not want to arm. I have the ESC set to auto-range on startup, but no-go. I can also get into programming via the radio (just to test the radio), but cannot change settings. So, I assume the ESC is not seeing the low throttle point. I'm trying to think of how an air radio would work and emulate that, but that's obviously not working.

I currently have the forward EPA set to 125%, and the reverse EPA set to 0. Trim is at the default 0. TBH, I didn't spend too much time trying this, but wanted to get a test run with 28 Ni cells just to see.

I have the 2.0 which is the same.....I had to use the pix stix convertor. Works like a champ after that.

Hmm, I know there are those who did not need the Pistix. I might just call Castle and see what they say if I don't see any responses here in the next hour or so...

I know it made it a snap to program.

Yeah, I WAS going to get one, but remember hearing others not needing it with the same radio/ESC. Maybe I should try the "fixed endpoint" setting instead of the auto-calibrate mode. Truthfully, I don't see myself programming via the stick - I was just trying it out to aid in radio troubleshooting.

I didn't have a pistix. For running the controller I had a hard time finding the right setting which was more like a aircraft radio setting (TH trim all the way to brake and adjusted the EPA accordingly). For programming I used an different model in the controller with default setting.

Brian, you're exactly right. I didn't need any tools to setup my HV-110. You need to take off the auto-calibrate in the castle program for the HV-110. Its the same problem I had in that it would never remember my endpoints. Once you set it to fixed endpoint, it will be easy to do. Your setup is close to mine. I have a Futaba 3PM 2.4ghz 500mW amplified with a HV-110, 8s Thunder Power, Neu 2215.

Hmm. I just got off the phone with Castle Tech support and they said there was no way to set the radio or ESC up to do this without the pistix. I didn't feel like arguing that it HAS been done so I just thanked him and moved on. I will definitely try the fixed point setting now (did not see the post before I called).

BTW: In case anyone is wondering, pistix is apparently pronounced "pie-sticks". I was saying "piss-sticks", lol. Foiled again by inconsistent English grammar! :dramatically shakes fists at sky:

You can definitely do without the pistix. It might help using it, but once I changed the HV settings to fixed endpoint, all I had to do was adjust the throttle EPA and trim until i got the HV-110 to arm. The only problem is that I have to hold brake to keep the motor from running. If i have the trigger in neutral position, the motor will run slowly. Its just an annoyance and I should fix it, but it works just fine.

That's what I did as well and to program the radio, I used to switch to another model memory with everything at defualt and I could get into program mode fine.

Eh, having to hold full brake is not really acceptable. I guess I'd better go order the pistix...

You do not need the pixstix. I have a DX3 with an HV110 and it arms just fine.

You cannot use auto calibration mode.

Actually, mine was very easy to setup. I can power mine up and view my settings through my USB and get back to you with them if you want.

Matt