Stubby lipo
 

is any one running in the uk with a stubby lipo if so how do they compare to the stick and saddle layouts

Dan Greenwood has just installed a Vampire one recently and can run it through the middle or across the back if he needs to. I am sure he will post soon, maybe with some pictures too (looks really good)

Yes I run a stubby across the back of mine, it does look very tidy and works well. It means you can run a standard chassis without all the dremelling needed for saddles.

I've kept the same 65/35 weight distribution as used with other layouts, but it centralises the weight and lowers the CoG, so in theory you get more grip, more responsiveness and less grip-roll. And it gives you the option to run the car a lot lighter with the same WD. I haven't actually tried this yet (still at about 1720g overall as I have a lot of ballast), but I think it will be a good idea indoors where there are no bumps.

Had my best result of the winter on Sunday using this layout at Kiddi :thumbsup:.

Why would a stubby LiPo lead to a lower CoG? :)

The stubby is about 100g lighter than saddles/stick. If you put that 100g back on using dense ballast flat on the chassis, the CoG drops.

Also, with a bit of dremelling the stubby sits a few mm lower in the chassis than a normal stick pack (as the chassis curves up at the edges), so there's a gain there too. This can also be done with saddles, but requires a bit more dremelling.

Stubby packs are (often) higher than conventional size packs, and thus result in a higher CoG. The idea of using the shorter packs is not to add extra weight under them, and ending up with an all-round lighter car.

Picture of mine attached.

Briefly, comparing to the T lipo setup I was running before with 5400 saddles, the stubby pack mounted forward (the pack is shorter than the gap so need a piece of foam or similair to mount front or back), the balance is within 0.1% further forward that the T setup and back (not side to side) it's 0.2% further back. It's 80g lighter overall like for like.

First run will be this weekend at Off Road Wars.

Oh forgot to add, to do this I've obviously removed the section of the vertical bracing to allow the stick through however I've also removed the nimh cell seperator bracings just under the middle which allows the cells to be mounted a few mm lower (as referred to above). However I had already done this on the T setup also so my test is like for like in this regard the 5400 cells and the stubby pack are the same height i.e. just under max legal limit for height.

thanks :thumbsup::thumbsup:
i think i will give this a try:):)

I'm not suggesting putting the ballast under the Lipo, that would raise the CoG. If the ballast and Lipo are both flat on the chassis the CoG calculations are:

Stubby Lipo (200g and 25mm high) = 200g x 12.5mm = 2500gmm
Lead ballast (100g, 3mm high) = 100g * 1.5mm = 150gmm
CoG position = ( 2500 + 150 ) / 300g = 8.8mm

If a standard Lipo is 300g and 23mm high, its CoG is 11.5mm (half its height).

So the (stubby with ballast) has a 2.7mm lower CoG than the (big lipo without ballast). The trick is finding somewhere to put the ballast, but because the pack is so small there's plenty of spare space on the chassis.

And you also have the option of not running the ballast and having a nice light car for smooth indoor tracks. Win win :).

Dan, I don't know if that car is fast, but it sure looks great! You do nice work!

Sorry but i forgot to ask can i do this with a saddle chassis:blush:

:thumbsup:

Thanks Chazz.

Leelar, you can but be aware there is already some of the internal bracing removed for the saddle setup. I tired this out on a saddle chassis but the car you see above has been built onto a new standard plastic chassis so it has full height bracings to the sides of the stubby lipo

Forget the lipo. Can we get some detail on your rear camber link set up?! :confused:

They are nothing special, Dan is just using the prototype "tower forward" rear shock tower that bring it further forward, shocks mounted on the rear and camber pick up points are on the tower. They are in the same positions as we normally run though just mounted on the tower instead of the rear bulkhead.

You're got good eyes :D

Darren has it covered, there are hole positions for E speed high, low and one in the middle :)

My primary reason for liking it is moving the rear wing forward which I beleive makes the car jump better though having only used it indoors so far at BWOC I can't say I've thoroughly tested this tower, I did run a home made mod all last year outdoors though but this proto tower is MUCH nicer.

Hassle Paul to bring it into production when the X Factory router has some spare capacity! :D

Looks very nice, moving the wing over the axle sounds like a worthwile improvement. Are any mods needed to the bulkhead to mount the tower in this position? Making the tower itself shouldn't be difficult.

Yes all new bulkhead will be needed, somthing we are working on/playing with right now.......

We have been working on tower forward for about a year, and have run into one problem which, so far, we have not been able to solve: Moving the ball stud is a long, tedious process. Ball studs screwed into CF need to go all the way through with a nut on the back, and there are too many things are in the way blocking access. To move a ball stud you've got to remove the tower, and it does not bolt on from the back with 4 EZ screws as the standard tower does.

It's a difficult problem, and, as Dan implies, we must find time to work on it, time we just don't have ATM. We have an idea as to the answer, but haven't had a chance to spend the time (and money) to see if it will work.

Chas,why not make the adjustment a "slot",with a washer under the ballstud and a washer under the nut on the other side it will clamp up ok,no need to strip anything down then to make adjustments.......slacken off and slide!!!