The gyro will be interesting to see if you can get the stabilisation to work at high speeds and not end up in a positive feedback loop - that would get very messy very quickly.

Gyro will make you look like a real R/C driver. I used to race oval and one day I tried a gyro and it made my car handle like it was on rails. It works too good and that's why it's banned from R/C racing. If you can hide it real good than you will be seeing the podium often :lol:, but for High Speed runs I think it's a must.

Interesting - I've never heard of it until now but looking around lots of articles - G190 seems to run for $44 so might pick one up to play with...

I won't bring it to the monster bash... promise!

Yep, gyros are fantastic for use in speed run cars...though only a few people used them last year for some reason.:neutral: If everyone used one, I bet the number of crashes would have been a whole lot less. I'm looking at getting a Futaba GY401 unit. I need a gyro for my heli anyway, so I'll be killing two birds with one stone. It's a very decent unit, so should keep LiteSpeed in check. :) They're dynamite for racing with though, like you say! Just hide it well, lol:whistle:

Othello...I see what you mean, and thanks for finding those graphs. At the end of the day, I can never be sure exactly how much power will be needed to get this car up to 150, but it's gonna be quite a lot...so I guess it's better to have the betteries able to supply more power than is needed in the end. I've heard several different opinions on how much power is needed to get past 150 (some say 6hp, some 4, etc) but it all depends on vehicle weight and other stuff. I reckon the MMM will be alright, though. It's rated at 200A constant, so some bursts above that hopefully won't be a problem. :)

Brushlessboy, I'm probably going to use my Nomadio React as long as it has the range.:yes:

Anyhoo, since I'm still waiting on a quote and can't afford the other bits yet, I just bought some pipe unblocker to de-anodise the ali bits:diablo:. I'll put up some pics when that and hacking-up the battery stay bits are done.:smile:

You could try and make a pack(s) using A123 2300mAh cells and if that's not enough voltage, go with as many 1100mAh cells as you can. The cells in Bosch's 36 volts power tool packs seems to have a 60A fuse and I'm wondering if it can actually handle 60A discharge. I might have to try it out and see how well they do. Here you can see the other pictures: http://www.rc-monster.com/forum/show...8&postcount=30

Nice little pack :lol:. I have attached the graph of some little bursts. This also shows the best regen braking action as well :surprised: at around 12 seconds I hit the brakes.

Thanks for the suggestion Lutach, but I think I'll stick with good ol' fashioned LiPo with this car.This chassis really lends itself to a 6S LiPo setup (the packs should fit beautifully), and I don't think the A123 cells would fit well. Their performance isn't really good enough for this sort of application either, but I appreciate the input! :)

Got it. Keep the pictures coming.

H'okay, got a very minor bit of progress done while I wait for funds to amass. Nothing exciting, but I thought I'd post anyway lol. I went down Tesco's and bought a bottle of Domestos Pipe Unblocker, and de-ano'd all the aluminium 3racing bits. I then took a hacksaw, file and wet & dry paper to the two main aluminium top deck support parts, in order to get rid of the stock-style battery clip mounts. These added unnecessary weight, and unnecessary weight gets the chop in this car! B) Even if it's the slightest thing. I also discovered that the rear body mount plate does perfectly well with only the two inner aluminium standoffs, losing no real rigidity. I might cut some excess material off of the plate itself at some point, but I'll leave that for now.

http://img.photobucket.com/albums/v6...r/DSCF0102.jpg
http://img.photobucket.com/albums/v6...r/DSCF0103.jpg

Sorry about the naff images btw...I just rushed them lol. Thanks for the interest in this by the way...I really appreciate it!

I have a few suggestions for you.

#1 If you use a gyro, you will need a super fast gyro and steering servo (GY611 is best) or you will get steering wag at high speed (ask me how I know)!

#2 Two wheel drive is VERY difficult for a top speed car because of traction issues. I run 4wd with a 1515 and I get tire smoke at 50% throttle (3800 watt power system). It accellerates 0 to 80 in 2 seconds. I have tried 2wd and could not get it to hook no matter what I did. It was like driving on ice.

#3 A 1515 is good for a maximum of 4000 watts before the efficiency goes in the toilet. However, it is very difficult to harness more than about 3000 watts anyway.

#4 Light weight is almost a moot point when you need to add alot of battery power (and weight) to it anyway. I mean, do not make it heavy if you do not have to. But, puting time and money into the best drive system and lipos you can get is far better for a top speed car.

Please forgive my negativity. I do not mean to rag on your car. The design looks very good indeed. However, I have gone round and round with these very issues with ALOT of money wasted and I would hate to see you go through the same thing.

It is a beautiful design and I wish you well with it. But, I have seen this time and time again and have been down this road myself.

Matt

No prob man, I'm all for input...especially form experienced people like yourself (I've seen your car on RCZ...what a piece of kit!). I answer to your points though:

1. I'll most likely be using a GY401 gyro, with as fast a steering servo as I can get hold of. I'd love to use a 611, but that's just simply out of my budget. I know what you mean by steering wag though...strangely, you actually get a similar thing happen on helicopters if you have the gain set too high; the tail wags. Obviously the 401 isn't quite as quick as the 611, so if I do get any issues, then hopefully turning the gain down will help.

2. 2WD...yep, it could cause real problems lol. I'm planning on using similar BSR tyres to what you've used before, but in terms of acceleration....well. I'm just gonna have to set up a nice, very smooth throttle curve up on the React and accelerate as gently as I possibly can. The React has a lot of useful mixing capabilities too, so I might be able to set up the steering to reduce its travel as throttle input increases which could help with control. By the way, I hope you don't mind my asking...but which of the BSR tyres would you recommend?

3. That's a good point. At the end of the day, the 4500W figure is really the absolute maximum that the system could deliver. As you know, the motor will only suck as much current (and so output the watts) that are needed to get it to a particular speed. Making the car ligher should reduce this figure, so that shouldn't be a problem. :)

4. I totally understand what you mean here too. The LiPos, motor etc are of course going to add weight and I am putting in what I think is the best power system for this chassis, but I may as well make the chassis as light as possible. The lighter the car, the less work the power system has to do. I'm not going overboard on it being lightweight in terms of price (the carbon chassis kit was barely any more expensive than the stock items lol), but if there's weight to be saved without much cost, I'll do it.

Thanks for your input man...it's given me a lot to think about (especially traction wise!) :).

Cool. Sounds good.

It looks like you have thought it all through. The one big thing that I have to advise is, if a 611 or another gyro just as fast, is out of your budget, I would say do not even use one. I have run a 401 in cars. They max out in performance at about 60 mph. Above that, they actually cause more problems than they cure. Of course, maybe you could mix it out with your React above a certain throttle?

I run BSR radials. Yours will be different than mine because I run them on touring car wheels.

They are awesome. But, I have shredded one in the past with too much wheel spin.

With two wheel drive, you will need alot of downforce for traction. But, that downforce will ultimately slow the car down. So, look for a good ballance.

Nic Case has alot of experience with 2wd and 4wd cars. Maybe he will chime in here. I may email him a link or call him and let him know about this thread to see if he has any suggestions.

Have fun with the car. That is what it is all about anyway!

Matt

Hmmm, ok. Well, I've been doing a lot of research into gyros and since I need a new gyro for my heli anyway (which I can use after it's done in LiteSpeed), I'm thinking I may as well get one anyway. If it works out, then great, if not...no real loss. As opposed to the 401 though, I've been looking at the Logictech 2100T. Everyone all over the net seems to agree that it's actually slightly better than the 401 and at a lower price, so I may go for that unit. I'll be sure to experiment with trying to mix out the gain on the React. :)

As for the tyres, thanks for letting me know which you're using. I'll also be using them on touring wheels, and *hopefully* the bodyshell with diffuser/undertray will provide the right amount of downforce with too much. You wouldn't believe the amount of time I spent researching that aspect lol.

Again, thanks for your help on this and that's be really great if you did send Nick this link. Thanks man. :)

Any updates? :)

Not as of yet unfortunately. I'm having a nightmare sourcing a Dodge Charger HS bodyshell for this car, which is a problem; the only place that I can find that sell it are Stormer, and their shopping cart doesn't appear to work with my card. This'd all be so much easier if oval racing shells weren't assymetrical.:no: So, I'm just trying to find another suitable shell that I actually *can* get hold of lol.

I have been ordering various bits for the chassis though, a lot of which are 3racing. It almost seems wrong to be ordering this many cheap "hopup" parts, but the truth is that the car needs to be as rigid and light as possible. Strangely, some of the 3racing parts are actually a bit cheaper than the components they replace, though better quality. I'm also still waiting on quotes for the motor pod parts, and been mulling over some other aspects.

Hopefully there'll be some updates soon. Thanks for the interest!:smile: