mayzie12 Posted December 22, 2015 Share Posted December 22, 2015 Thought i would start a nice fresh topic for the car this year as it will be my main focus! (He says) I'm pretty happy with how the car ran this year. The strange mix of Hong Nor Truggy and Buggy parts to make it into a short-course, followed by custom made shock towers to turning it into an on road car seemed to work surprisingly well. Managed 102mph on 6s with a 1717 with a EzRun. Sadly the EzRun couldn't handle the 2200kv i stuck in it for long enough to get a run, also the shell is a little bit battered but should be okay for practice. Im hoping to come down to the practice in April as university finishes around then and there is always a a couple of weeks from then until the exams so hopefully it fits in. The car as it stands at the minute has not been touched since the event in September. Not planning in changing much. Would like to make the suspension a little bit stiffer, especially at the back. Another thing doing will be a a new battery tray, luckily having a 3d printer working now should make this pretty easy! Finally i will be picking up a Hobbywing Max5 to stick in there and will be testing it parallel to the MGM which broke before i even had a chance to run the car. its now been repaired (at the cost of a couple of legs and lungs) and hopefully its back to what its meant to be as it was never the same since it broke the first time. Off uni now until the middle of January so should hopefully make some progress until then! (Apologies for crappy pics, phone is on its last legs!) 1 Quote Link to comment Share on other sites More sharing options...
Oh How Original Posted December 22, 2015 Share Posted December 22, 2015 Hmmm, both cars reached 102mph? Sounds a bit Hollywood fixed to me hehe. Joking aside, nice one on hitting 100+! Shall be following this. Quote Link to comment Share on other sites More sharing options...
mayzie12 Posted December 22, 2015 Author Share Posted December 22, 2015 The hyper reached 102 in 2014, on 8s with the 250a MGM and the 1717. Basically using brute power Doing the same speed in the Hong Nor on only 6s with a 150a esc either showed the car is way better, or the MGM was bad compared to the Hobbywing! Quote Link to comment Share on other sites More sharing options...
Oh How Original Posted December 22, 2015 Share Posted December 22, 2015 Purely judging from peoples topics, MGM seem to be quite hit and miss? I could be completely wrong, but for what you pay, there seems to be a lot of them that won't work from the off or die prematurely. So I'm assuming you're planning on putting the MGM and 1717 into the HN on 8s just to see what happens? I'd imagine the HN is a lot slippier so you should achieve 110+ you'd think. Looking forward to seeing what happens either way! Quote Link to comment Share on other sites More sharing options...
ajlovering Posted December 22, 2015 Share Posted December 22, 2015 9 hours ago, mayzie12 said: The hyper reached 102 in 2014, on 8s with the 250a MGM and the 1717. Basically using brute power Doing the same speed in the Hong Nor on only 6s with a 150a esc either showed the car is way better, or the MGM was bad compared to the Hobbywing! 4S 161mph.......LOL Quote Link to comment Share on other sites More sharing options...
mayzie12 Posted December 22, 2015 Author Share Posted December 22, 2015 I will be trying the MGM and a Max5 in it with both motors on 8s. Ideally i want 200kph but you dont always get what you want! MGMs are a bit weird yes. But they are still fantastic ESCs, even down to how smooth they are compared to a hobbywing. Also there really isnt anyone else out there that is producing these high powered esc's and as said they can be repaired so you are never at a total loss. 2 hours ago, ajlovering said: 4S 161mph.......LOL Was that run done on a hobbywing on 4s??? Quote Link to comment Share on other sites More sharing options...
.AJ. Posted December 22, 2015 Share Posted December 22, 2015 What KV is your TP motor? Quote Link to comment Share on other sites More sharing options...
mayzie12 Posted December 22, 2015 Author Share Posted December 22, 2015 34 minutes ago, .AJ. said: What KV is your TP motor? 2200kv, 106mm long can. Quote Link to comment Share on other sites More sharing options...
.AJ. Posted December 22, 2015 Share Posted December 22, 2015 Cool, I've got the 1400kv 92mm version in mine, fingers crossed being lower KV it should be a bit more friendly to my esc on 8s Quote Link to comment Share on other sites More sharing options...
mayzie12 Posted December 22, 2015 Author Share Posted December 22, 2015 Aye should be. The 2200kv was the motor that blew my EzRun. Although to be fair i did get about 5 almost full speed passes out of it first, just not with the traps set as someone was retrieving there car! Quote Link to comment Share on other sites More sharing options...
ajlovering Posted December 23, 2015 Share Posted December 23, 2015 17 hours ago, mayzie12 said: I will be trying the MGM and a Max5 in it with both motors on 8s. Ideally i want 200kph but you dont always get what you want! MGMs are a bit weird yes. But they are still fantastic ESCs, even down to how smooth they are compared to a hobbywing. Also there really isnt anyone else out there that is producing these high powered esc's and as said they can be repaired so you are never at a total loss. Was that run done on a hobbywing on 4s??? Not sure. This is the video https://www.youtube.com/watch?v=PUXy8M5Bpqw Quote Link to comment Share on other sites More sharing options...
mayzie12 Posted December 23, 2015 Author Share Posted December 23, 2015 13 hours ago, ajlovering said: Not sure. This is the video https://www.youtube.com/watch?v=PUXy8M5Bpqw We never see under their cars anyway.... Quote Link to comment Share on other sites More sharing options...
mayzie12 Posted December 26, 2015 Author Share Posted December 26, 2015 ESC mount is done. Need to get some small rubber donuts to give the esc a bit of shock protection but it all seems to fit nicely. Have included hexes in it too for captive nuts. Next is the battery tray which will be a 8-10hour print whatever way i do it.... Quote Link to comment Share on other sites More sharing options...
mayzie12 Posted December 27, 2015 Author Share Posted December 27, 2015 Managed to get the lipo tray designed today too. Stuck it into Cura and it says it will be around a 14hr print! No idea if i have enough filament left on my roll either. Will just need to set it going one day and hope for the best. Added in loops on the side for the velcro straps then two cut outs which some side bars will screw into. Will be designing them up soon too so i can secure the sides of the body a bit better. Rendered the lipo tray while was in solidworks. Quote Link to comment Share on other sites More sharing options...
mayzie12 Posted December 30, 2015 Author Share Posted December 30, 2015 Attempted to print the lipo tray with the filament i had left, and it ran out, around 20mm before the top..... Good news is it all fits in the car, velcro slots are just the right size too. Now printing another in blue with the new filament. Quote Link to comment Share on other sites More sharing options...
mayzie12 Posted January 6, 2016 Author Share Posted January 6, 2016 Right, quite a lot of stuff done to the car. Front bumper made. total of 3 parts and it supports the front of the body well so it cant tuck under. Also made a couple of nerf bars for each side. Probably going to try and get a strip of magnets each side on them and the body so it holds the body in. Even if i dont do the thery still provide good support to stop the body flapping around as much. Finally lipo tray was done. Did take forever in the end but the lipos fit nice and snug and i even had Velcro straps to fit! Been also looking in to making my own body out of fibre glass. Not quite sure how to make the plug. Thinking MDF for a very basic shape then body filler to get the curves. Also thinking about the design and looking into center of pressure and center of gravity relationships. Seem to be finding you want them as close as possible? also seem to be seeing the rear wheels in the middle of the body a lot in a few streamliners so im thinking this must be relevant too. Im sure Tony will be along and putting me right! Quote Link to comment Share on other sites More sharing options...
Carpmart Posted January 6, 2016 Share Posted January 6, 2016 Coming along nicely there now... Good work Sir! 1 Quote Link to comment Share on other sites More sharing options...
ajlovering Posted January 6, 2016 Share Posted January 6, 2016 ...as if by magic.... Firstly the shape. You want the centre of pressure behind the centre of gravity. Think of a dart. Weight at the front and all the drag at the back. Try throwing it backwards and thats what happens to your car if you get them the wrong way around. To get the drag further back most people add a wing. This adds drag to the back and stabilises the car. The car can be unstable in both the horizontal and vertical planes so if the pressure is forward the car will flip or spin. Both are symptoms of drag pressure too far forward. A simple cure is just tape a paper streamer to the car at the back and it will stop flipping. A cut off body at he back also add huge drag So if you think about the drag for a second it acts on the centre of gravity. If its close to the CofG then you need a large drag to get the same moment of drag. Further away you can have less drag and get the same moment. Adding a wing at he back will work but better is to extend the body far behind the rear wheels and add a small wing. This does 2 things it smooths the airflow over the rear so when the air that is separated from the front moving forward rejoins at the back less turbulence is created and less drag. Secondly a small wing far from the CofG will stabilise the car better than a large wing close to the CofG with less drag so the car can go faster. You also want to have a pointed front to ensure the air is separated without causing a pressure wave. A large angle will cause a wave or pressure build up a the front and de stabilise the car and cause more drag. So to sum up. Make the body twice as long as the car with the rear wheels around the middle of the body. This isnt rocket science as it was what made the Bluebird very fast in 1929 So next is how to make it. I have used all sorts of material for the plug but best is polyurethane foam. Get the high density stuff if you can afford it. You can buy the liquid also and pour it into an existing body to make a copy then reshape the body. Once the shape is near enough you need to cover it all with filler and sand it down then cover with smoothing material such as Pattern Coat http://www.easycomposites.co.uk/#!/patterns-moulds-and-tooling/pattern-making/composite-pattern-coat-primer.html. The primer is good enough, you dont need the high gloss. Look at all the videos online on how to make a 2 piece mold if its required. I usually design the bodies to come out in one piece If you need any furthur assistance drop me a PM or a mail or give me a call Best of luck 1 Quote Link to comment Share on other sites More sharing options...
Carpmart Posted January 6, 2016 Share Posted January 6, 2016 Great post Tony and fantastic data/information for all us 'wannabe' speedsters! Quote Link to comment Share on other sites More sharing options...
mayzie12 Posted January 6, 2016 Author Share Posted January 6, 2016 Excellent Tony. Thanks a lot, few more things to look into before having a crack at a design! Already found that site you linked and looked at some of the stuff. With the foam, are you able to re-use the plug? or is it a case of using the liquid stuff in the 1st shell made to make a reuseable one? Quote Link to comment Share on other sites More sharing options...
Tamiyacowboy Posted January 6, 2016 Share Posted January 6, 2016 (edited) What about two stage shock pistions ? inside the shock is a single piston with a couple holes jammed through it, oil passes through. a two stage system has two piston plates inside when the shock is compressed both piston plates samwich together , out of the eight holes in the piston plates only four will allow oil trough when compressed. when the shock rebounds back up under spring force all eight holes open up, the two plates open and a large void is created,the void and the eight holes allow the shock to rebound back quicker. its used in off roaders to butter the rebound on hard bounces. where you want the shock already extended for the next bump it encounters. you see this in off roaders when the do the kangaroo hops when traveling whoops, having a 3d printer and ABS you could print out a couple prototype piston tops (shove .5mm holes in them and bur them to 1mm if needed) instead of trying to find and by the rpm two stage shock kits (google is helpful, throws up images of how the work inside shock, and great for modeling a prototype high speed set), i only found them for 1/10th scale to. so some 3d printing could bring 8th scale and 5th scale two stage kits to the markets. I also thought about cantilever shock setup , taking the shocks inboard and replacing that bulk of the shock bodys and likes into the centerline of chassis (like a twin hammer), that could also help on drag giving a smoother airflow through the a-arm and front end inside of the wheel and body. and on the rear would it help reduce drag maybe , more smoother an airflow the less drag vortices are seen ? Edited January 6, 2016 by Tamiyacowboy Quote Link to comment Share on other sites More sharing options...
ajlovering Posted January 8, 2016 Share Posted January 8, 2016 Or take the shock off....... Quote Link to comment Share on other sites More sharing options...
mayzie12 Posted January 27, 2016 Author Share Posted January 27, 2016 Well the MGM went back to the company again as i went to turn it on and well, they forgot to solder the switch on..... A bit amateur but hey, things happen. Since this i have printed a ESC mount for an xerun150a just to get the car moving, when a dry day comes. Only problem is we haven't had a dry day since around November! Also made a small receiver box just to keep things neat. Next big decision is whether to get a Hobbywing Max5 of a Castle XLX. Decisions decision! Still thinking about making a body, just would rather get the car moving first properly so will purchase the chosen ESC before all the materials to make the body as it seems around £100 to do so. A pic of the car as it stands. Also i finally got another phone so the pictures should be better now. 1 Quote Link to comment Share on other sites More sharing options...
Brandon Posted March 19, 2016 Share Posted March 19, 2016 Any progress on this build? Quote Link to comment Share on other sites More sharing options...
Carpmart Posted March 20, 2016 Share Posted March 20, 2016 As above... What ya done to it dude? Quote Link to comment Share on other sites More sharing options...
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