m1tch_87 Posted February 8, 2016 Author Share Posted February 8, 2016 35 minutes ago, Tamiyacowboy said: Fluid dynamics : you can do this kind of modeling with Blender, but be warned its for those who can already or do have a grasp on 3d modeling. heres a video of an airfoil fluid dynamics model using blender https://www.youtube.com/watch?v=WXq2fdArijM Thanks for the info, I think I might try out a DIY physical approach to the airflow as I don't have a background in 3D modeling unfortunately - otherwise it would be amazing! Quote Link to comment Share on other sites More sharing options...
Tamiyacowboy Posted February 8, 2016 Share Posted February 8, 2016 There are lots of videos on blender modeling by a user named Tutor4u on youtube from the very basic to modeling fluids. ie water and the likes. air is a fluid , yup its weird to think that but thats what air is a fluid. to start modeling is very easy, blender is a free program and is very very powerful, it allows you to model things youwould never think of and even create games. the first model i did was using tutor4u and the coffee cup, i followed him step by step and ended up with a coffee cup, from there i moved onto a wine glass , and then onto a beach scene. its a great thing to mess with when we have these nasty days or have a few hours you need to waste away. once you have a few basics your already on your way to designing a body, then you can use tutorials to model some fluid dynamics like water , it give syou an idea on how the air flows around as your able to see the effect the model will have on the water particals you add. its nice to because you have an object you can interact with inside the computer so no need to keep refining real life models, you can refine your 3d model as you learn, and it allows for mistakes to bemade and corrected without the hassle you would find in the real world. 1 Quote Link to comment Share on other sites More sharing options...
Wrighty8766 Posted February 8, 2016 Share Posted February 8, 2016 I think you would find the carnage won't hold up to any real power, you might be better looking at a hyper 10tt or Losi ten T Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 8, 2016 Author Share Posted February 8, 2016 6 hours ago, Tamiyacowboy said: There are lots of videos on blender modeling by a user named Tutor4u on youtube from the very basic to modeling fluids. ie water and the likes. air is a fluid , yup its weird to think that but thats what air is a fluid. to start modeling is very easy, blender is a free program and is very very powerful, it allows you to model things youwould never think of and even create games. the first model i did was using tutor4u and the coffee cup, i followed him step by step and ended up with a coffee cup, from there i moved onto a wine glass , and then onto a beach scene. its a great thing to mess with when we have these nasty days or have a few hours you need to waste away. once you have a few basics your already on your way to designing a body, then you can use tutorials to model some fluid dynamics like water , it give syou an idea on how the air flows around as your able to see the effect the model will have on the water particals you add. its nice to because you have an object you can interact with inside the computer so no need to keep refining real life models, you can refine your 3d model as you learn, and it allows for mistakes to bemade and corrected without the hassle you would find in the real world. Thanks for that, I have been meaning to look into 3D drawings, perhaps this is the perfect time to start! 6 hours ago, Wrighty8766 said: I think you would find the carnage won't hold up to any real power, you might be better looking at a hyper 10tt or Losi ten T I will see how it goes, its just a cheap starter car mainly for me to learn on, if it does well then great, if not I know what I need to upgrade or buy next, I will be looking into strengthening the car as best as I can but its got a lot of metal parts as standard so not bad for a cheap model. I know there are ways to strengthen plastic parts by boiling them and I might be looking to cross brace parts anyway - its all a learning curve! I do really appreciate everyones help on this, its such a knowledgeable forum, sorry for all my newbie questions about RC, I do know a bit about 2 strokes and some of the basic principles, just need to get up to speed in what is best practice and what works and what doesn't. Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 10, 2016 Author Share Posted February 10, 2016 I have managed to piece together some specs from the manual and spare parts to work out the gearing specs as well as the top speed etc using a calculator. Here are the specs: Clutch bell - 14t Spur gear - single speed (std) is a 50t, 2 speed has a 45t second gear as an optional extra Diff drive - 13t Diff spur - 38t Diff bevel S - 10t Diff bevel B - 13t Open wheel class requires a minimum of a 90mm wheel - rolling circumference is 282.7mm It seems that I don't need to use the diff bevel gears in the calculation Plugging the figures in and going for a max rpm of 35,000 and the larger 50t spur gear = 110.8mph Plugging the figures in and going for a max rpm of 35,000 with the optional 45t spur gear = 123.1mph It would seem that due to the larger wheels the gearing has been increased simply due to the extra rolling circumference, the stock wheels are a 2.8" or 71.2mm diameter giving a rolling circumference of 223mm (without tyre though). Even using those specs the speeds drop to 87.6mph with the 50t or 97.3mph with the optional 45t 2nd gear - I have a feeling the standard engine won't exactly rev that high though but its an interesting drop in top speed due to the tyre size change. The marketing figure for the GO 18 engine is at 36,000 rpm, but I am guessing that's not going to happen as I am sure that is probably going to be unloaded in perfect conditions - using 30,000rpm the top speed even with the optional 2nd its in the low 80s. I have used the below calculator: http://www.radiocontrolinfo.com/information/rc-calculators/rc-car-calculator/#Speed Hopefully the project car will arrive tomorrow - excited in seeing it properly and checking things over, the engine is broken in and has had a few tanks though it, tempted to take the engine apart and check the wear on all surfaces plus seal the engine with some high temp silicone. The IC small block record is currently at 101.01 mph The open wheel record is currently at 99.61 mph My goal for this project is to get over the 100mph mark - looks like I might be able to up the gearing with the use of the larger wheels required for the open wheel class, will need to think about gearing with the IC small block class though. Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 11, 2016 Author Share Posted February 11, 2016 Just doing a bit more research on the FTX range, it seems that the FTX Colt has a 41t spur gear so I might be able to run: 16T clutch bell from the FTX Holigan - up from 14T 41T spur gear from the FTX Colt - down from 50T or 45T 14T diff drive from FTX Colt - up from 13T I am however going to look into the different clutch bells - as its on a generic engine there could be far more options if the spec is the same - there is also the taller gearing through the use of larger wheels and tyres. Quote Link to comment Share on other sites More sharing options...
ajlovering Posted February 12, 2016 Share Posted February 12, 2016 Get a clutch bell with a threaded end. You can add any gear you want then 1 Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 12, 2016 Author Share Posted February 12, 2016 (edited) 1 hour ago, ajlovering said: Get a clutch bell with a threaded end. You can add any gear you want then I did see some of those around, will look to upgrade to one of those so I can swap out the gears, I believe the gearing is .6 mod so there should be a few options. The project car has arrived now, its in the sort of condition I expected to find a used off road RC lol spent last night removing parts and cleaning them, there are a few parts that I need to sort though: Front dogbone/CVTs are bent - replacement cost £10 Front shock tower looks to have had some glue or something added (guessing from an impact) - replacement cost of £2.50 or £10 for a carbon fibre one Receiver needs a new aerial - perhaps I should upgrade to a better one at this point? Cost - £unknown Bodywork - its shot, the rear half of the bodywork might have been damaged in transit, will be replacing anyway. For the mods I will be swapping out the suspension to shorter on road shocks (rather than modding the OEM ones) to give a lower ride height - can then fit the longer ones if I do want to practice with additional ride height! Wheel and tyre combo were 115mm diameter so well within the open wheel class, will be looking at perhaps buggy wheels with autocross tyres which would give grip on dusty on road conditions. Car width including tyres comes to around 330mm so a 200mm touring car body might not fit! but could be due to the wheels, will upgrade the plastic hex drive nuts as well, they seem fine at the moment though. Some comments on the car so far: Metal parts seem well built and strong Plastic A arms seem to also be made well and are rigid Stock suspension is adjustable using some screw collars - think the caps are metal but the bodies are plastic Engine internally is pretty clean although I have noticed that the internal part of the 1 way bearing seems to be slightly rusty Engine has very good compression, internals look good Exhaust is plastic but has a metal manifold - looked at options to create a rear facing exhaust rather than doubling back at the side for better aero As mentioned the front dogbone/CVT joints need replacing and will replace the front suspension tower Just inputting the details of the car into the speed calculator - the 115mm wheel diameter does give the car a good theoretical top end even with the 50t stock gearing, will will pulling the diff apart tonight I think and I will check the number of teeth on the pinion and spur but I believe they are correct. I might also look to run the car as 2wd only instead - will be doing some speed tests to see what works better - the 4wd system would give additional grip but have additional driveline losses vs the 2wd setup which would have less grip but not rob the engine of power. Might do a speed test by removing the front dogbone/CVT joints as they need replacing anyway, will run RWD and test vs 4WD when I refit the new ones using the exact same setup. Edited February 12, 2016 by m1tch_87 Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 12, 2016 Author Share Posted February 12, 2016 Arg, I have made a fairly large mistake using the calculator, usually it asks for the circumference of the wheel, this calculator asks for the diameter! Will have to rethink! Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 12, 2016 Author Share Posted February 12, 2016 Had another think about the gearing, I could look at changing to the 64p gears which will give a lot of other options for gears, however I have thought of another idea which will basically give an easier swap out of gearing - convert the clutch bell to accept electric pinion gears. I am going to look to machine a collar to go around the clutch bell which then outputs a standard motor sized pinion shaft size which a standard electric pinion gear can attach to. Working out the gearing again using the stock gearing but just changing the teeth on the clutch bell it would see I would need to run something like a 30t pinion to a 45t or 50t spur (retaining the stock hop ups for the 2 speed box you can get for this model). As I found before I think I can run a FTX Colt 41t spur gear but I think it might be a better idea to run a 2 speed gearbox instead as I am not sure how slow the car will be accelerating with such a tall gear. I am using the max rpm of the engine at 30,000 - is this about right for a basic .18 engine? I have also found that if I swap to the smaller 1/10 touring car wheels at 65mm I would need a crazy number of teeth to be able to get any sort of top speed out of it - not sure what gearing is being used on other Nitro cars to get to their top speeds! I guess the electric powered cars have a higher RPM which means that they get a higher speed through additional RPM rather than gearing. I will have a think about it over the weekend, need to get some stock setups first, might also see if I can get different diff drive gears as well although I might be stuck with either 13t or 14t so might have to look to gear up using the clutch/spur gears as well as the larger wheel size. Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 12, 2016 Author Share Posted February 12, 2016 I have had a chat with my father in law who has a decent lathe, plan is to machine the clutch bell to make it threaded where the teeth usually are, then make a basic adaptor which will screw onto the threads on the clutch bell to then convert to the standard electric output shaft size - can then use any pinion gears on the market so could gear 1:1 in 2nd gear eg 45 and 45. It wouldn't be direct drive as the diffs would reduce the gearing but having the adaptor would mean that I have a large number of options, the engine mounts are adjustable as well so can get the correct gear mesh. Quote Link to comment Share on other sites More sharing options...
ajlovering Posted February 12, 2016 Share Posted February 12, 2016 Use MOD 1 gears 1 Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 12, 2016 Author Share Posted February 12, 2016 2 hours ago, ajlovering said: Use MOD 1 gears I will look into how the spur gear is connected to the gearbox on the car, should be able to fit a different non standard spur gear - will look to uprate to the better gears so will look at mod 1 gears as suggested. Will post up some photos later. Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 12, 2016 Author Share Posted February 12, 2016 Here are some photos and the work I have been doing over the past few evenings: As the RC arrived: I dropped the suspension to the lowest setting, its pretty low but still a bit high: I then started to take things apart and clean them, its been offroad quite a bit: Front dogbone CVD joints were bent probably from hitting something too hard: Overall starting weight is 2,301g Front bumper weighs 30 grams - 1.3% weight reduction Stock wheels and tyres weigh 473 grams - tyres seem to be quite heavy Removed the engine....needs a clean Better! Internally the engine is pretty good, but of muck on the outside but that cleaned up well Bit of rust on the 1 way bearing though so will clean that up when I seal the engine soon: Cleaned the parts in an ultrasonic bath Cleaned up ok in the end: Took out the fuel tank and also the battery box, the box with contents comes to 159g: The box on is own was 25g I will look to swap out the battery for a lipo rather than 4 AA batteries - they are probably about as heavy as the engine! Overall not bad, I will take apart the diffs soon and get some new oil as well as some bearing oil but I am quite tempted to give the car an initial run to see what it does, top speed should work out to be around 38mph using the gear calculator so anything over 35 I will be happy with for an initial bone stock run - I have straighted the front dogbones but might look to run with them disconnected to see if RWD vs 4WD is better. Quote Link to comment Share on other sites More sharing options...
ajlovering Posted February 13, 2016 Share Posted February 13, 2016 Take the piston and liner out of the engine. Push the piston up into the liner. The piston should get tight about halfway up and stop about 5mm from the top. If it is loose up to about 3mm from the top and then reaches the top the engine is had it. A piston and liner is the same price as an engine so best to throw it away and get another one Cheers Tony Quote Link to comment Share on other sites More sharing options...
Wrighty8766 Posted February 13, 2016 Share Posted February 13, 2016 (edited) What you could do to open up many gearing options is make a centre spool to replace what is already there, depending on the bearing size on the centre diff you need to buy some shaft off eBay and make one of these You can buy spur gear adapters off eBay that allow you to use from 32t-44t and they are available with 5mm/6mm/8mm bore Edited February 13, 2016 by Wrighty8766 Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 13, 2016 Author Share Posted February 13, 2016 2 hours ago, Wrighty8766 said: What you could do to open up many gearing options is make a centre spool to replace what is already there, depending on the bearing size on the centre diff you need to buy some shaft off eBay and make one of these You can buy spur gear adapters off eBay that allow you to use from 32t-44t and they are available with 5mm/6mm/8mm bore Thanks for that, I did notice that HPI and a few other have an adapter to allow for easy interchange of spur gears, the shaft diameter in the centre diff is 5mm - have just taken that out to inspect and to take measurements. It seems the same size as the 5mm mod 1 pinion gears so I might even get away with using a pinion gear and mesh with another pinion gear when I convert the clutch bell to run electric pinions - is there a name for that centre diff setup? I think i will be just running the single gear rather than a 2 speed due to the added complication of having 2 speeds - will probably convert to RWD to reduce the load on the engine as well, will need to see about grip levels with just RWD vs 4WD but its nice to have the option. 2 hours ago, ajlovering said: Take the piston and liner out of the engine. Push the piston up into the liner. The piston should get tight about halfway up and stop about 5mm from the top. If it is loose up to about 3mm from the top and then reaches the top the engine is had it. A piston and liner is the same price as an engine so best to throw it away and get another one Cheers Tony Thanks Tony, I will pull the engine out again - was just taking it out to check the general condition, will pull the liner out and check everything over including the bearings etc when I get a flywheel removal tool. The engine does seem to have very good compression, will pull everything out again now that I am happy with the general condition. Are there any conversion kits out there to convert to a bump start setup so that I don't have the parasitic loss due to the 1 way bearing at all? Does anyone know what the the lowest gear ratio a 18 engine can pull? I will be looking to increase the engine size soon, but might be interesting to run in the IC small block class as well. Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 13, 2016 Author Share Posted February 13, 2016 Just took the engine out again - those adjustable engine mounts are a faff! Anyway, took the piston and liner out, the piston gets tight from just after half way and is tight at around 5mm from the top - I can tell the engine is used and is on its way out but should still be fine for practice. i can see that there is a slight discoloration in the brass so it could have been run slightly too hot at some point. I will use this engine for practice and then look to get a .18 and a larger engine for the speed runs. Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 14, 2016 Author Share Posted February 14, 2016 Some minor updates, still working through cleaning everything, I have ordered the 41T spur gear from the FTX Colt to see how much difference it makes - won't be in the final setup but will give some extra top end to see what the acceleration difference is when comparing setups. Here is a photo of the liner, the original GO18 engine is kinda a test engine now just to propel the car rather than for any speed runs etc - will also look to port it as well as its on its way out to see how much difference it makes. I have also looked at the suspension setup to see how low I can get the chassis along with the fact that I want to make the frontal area as low as possible - buggies usually have the front struts up high which isn't idea for aero. These are the original shocks which are wound all the way up to give the minimum clearance - they are the standard off road long shocks as well so quite happy that they fit a different re purposed mounting hole. I do need to check that the shocks actually work at that extreme angle, I would almost simply use a tie rod end or something and basically run without suspension - with the suspension being via the tyres. Just having a play around with possible combos, the whole chassis is basically now the same height as the wheels and tyres (115mm). Quote Link to comment Share on other sites More sharing options...
ajlovering Posted February 14, 2016 Share Posted February 14, 2016 What you need is the the suspension not to travel but have a large air gap underneath. Take the shocks off and then the ball ends and put fuel tube over the shock shafts to stop to make them really stiff. Alternatively replace the shocks with tie rods. You will have enough give in the tyres Cheers 1 Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 14, 2016 Author Share Posted February 14, 2016 48 minutes ago, ajlovering said: What you need is the the suspension not to travel but have a large air gap underneath. Take the shocks off and then the ball ends and put fuel tube over the shock shafts to stop to make them really stiff. Alternatively replace the shocks with tie rods. You will have enough give in the tyres Cheers Thanks for the input, I will probably convert to the tierods - will be running the car as low as I can to the ground, was just looking at some of the lower mounting points to ensure that I had the least restriction with regards to airflow. I will be getting a buggy body for it soon and have some new wheels and tyres coming for on road use, once I get those fitted I can see the length of tierod I will need to run it as low as possible, The new wheels and tyres should also reduce overall drag as they are on road tyres, will look to run a .18 engine initially as a testbed, will also look to run a front splitter and rear diffuser, will also look at possible wing options. I also need to ensure that the engine is suitably cooled but will see how it goes with regards to the body fitment, with regards to other aero work I will probably box in the front and rear A arms due to the lattice work adding drag - might look at some of the heat shrink coverings used on the RC aircraft. Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 16, 2016 Author Share Posted February 16, 2016 Minor update, I have upgraded the plastic hex drive nuts to metal rather than plastic and have now got some new front CVD shafts, I did straighten the original ones out so will run with those whilst practicing etc. I am also on the look out for some m3 threaded bar so that I can make up some tierods etc to delete the suspension. Quote Link to comment Share on other sites More sharing options...
.AJ. Posted February 16, 2016 Share Posted February 16, 2016 You can buy m3 stud on eBay http://www.ebay.co.uk/itm/A2-304-stainless-steel-studding-1m-metre-metric-allthread-stud-bar-threaded-rod-/262017437781?var=&hash=item3d0174d055:m:m_AHPWd6uzCnOICPZ9jkKHw Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 16, 2016 Author Share Posted February 16, 2016 1 hour ago, .AJ. said: You can buy m3 stud on eBay http://www.ebay.co.uk/itm/A2-304-stainless-steel-studding-1m-metre-metric-allthread-stud-bar-threaded-rod-/262017437781?var=&hash=item3d0174d055:m:m_AHPWd6uzCnOICPZ9jkKHw Yeah I will look to get some studding from ebay, was just looking around locally before ordering online. I might also look at some different engine spacers as the stand offs used for PCs are M3 - might give me a few more adjustments etc although my engine does have fully adjustable mounts - they are just a bit of a faff when taking the engine off as the flywheel gets in the way when trying to slid it off forward or backwards. Quote Link to comment Share on other sites More sharing options...
m1tch_87 Posted February 28, 2016 Author Share Posted February 28, 2016 Few updates on the project: M3 studding has arrived for the suspension lock out .28 engine has arrived - 3.5bhp @ 28,000 2 speed HPI Savage X transmission has arrived FTX Vantage buggy body on the way 1/8 on road wheels have arrived (100mm diameter) - just awaiting the hex adaptors I have worked out the gearing that I need to run for ROSSA records, the setup will be something along the lines of: .28 engine with 23t clutch bell 14t pinion on HPI input shaft on transmission Diffs will remain standard This gearing looks fairly mental when you look at the clutch bell to engine, however the transmission drops the gearing which is then further dropped by the diff - the 2nd gear is at 1.54:1 with the diffs being at 2.92:1. Plugging all of the figures into an online calculator here are the below speeds in top gear with regards to the pinion (using a 23t clutch bell): 23t = 72.70 mph22t = 75.99 mph21t = 79.61 mph20t = 83.59 mph19t = 87.99 mph18t = 92.88 mph17t = 98.35 mph16t = 104.49 mph15t = 111.46 mph14t = 119.42 mph13t = 128.61 mph12t = 139.32 mph Here are the speeds in 1st: 23t = 50.42 mph22t = 52.72 mph21t = 55.23 mph20t = 57.99 mph19t = 61.04 mph18t = 64.43 mph17t = 68.22 mph16t = 72.48 mph15t = 77.32 mph14t = 82.84 mph13t = 89.21 mph12t = 96.64 mph Looking at the speeds I think I will look to go for the slightly higher gearing as I know that there will be drag to consider so I would rather the engine still accelerating - I will be looking to fit either a 13t or 14t pinion, will probably go with a 14t as that will give me some head way above the ROSSA record and also mean that 1st gear should be attainable. In other news I have finally taken out the stock FTX engine with the GO18 engine, the carb needs cleaning as it didn't prime easily - or there is an air leak somewhere in the system. I did however have an issue where the throttle pinned open which resulted in contact with a fence and a snapped lower front A arm - its fine though as the part is only £5 for a set of 2 so have ordered more. Looking at the transmitter I noticed that one of the batteries weren't correctly inserted which I think meant that the transmitter glitched out slightly. I have a brand new 3 channel transmitter and receiver to be fitted soon - I might need the 3rd channel to run a separate servo for the brakes due to the layout of the 2 speed HPI box. The next steps for this project is to mount the larger .28 engine in the stock chassis and then run it with a standard 14t clutch bell as I will need to break the engine in slowly to get the best performance before increasing the gearing. I have a plate of aluminium coming and will be looking to extend the chassis backwards slightly (as the diffs and suspension bolt down onto the chassis) - will keep the front end stock and simply extend the rear slightly to accommodate the transmission. I will be mounting the HPI box sideways rather than vertically as the engine will be mounted to one side, there are OEM mounts on the side of the transmission which i can re-purpose. One thing to note is that due to the light weight chassis this FTX went off like a rocket when at full throttle, it was faster than the heavier HPI Pulse 4.6 1/8 boggy my father in law had and I know that the FTX is geared to run at around 40mph @ 30k rpm. Quote Link to comment Share on other sites More sharing options...
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