I did the project as Impulce requested. Since RCU was under maintainace I did it on paper...and you know I''m lazy (I don''t have a scanner too) so here you go! Pm me for any questions.

What on earth is all that hieroglyphics??

Put the lot into a spreadsheet so the user can adjust the inputs and see th results.

Cheers

Honestly it''s the simplest it can be...I explaining everything step by step and in the end there''s the final formula for calculations. I also write what every single variable represents. Give it a try and you''ll understand for sure.

WOW that a lot of math and calculations!!! just trying to undersand!!!

Here''s one of the calcs i did up a while ago. (R/C)= fun/smiles!!

Can you put all this quantum mechanics into simple English please [&:]

Quantum mechanics? Well they were teaching us these things at high schooll and i can show you a 3rd grade book if you don''t believe me (it must be somewhere in a bookshelf...it''s been 6years till I last saw it, LOL)! Honestly there''s nothing hard if you spend some time reading it all. If you trust me rely on the final equations. All the other stuff is simply the mathematical documentation of the final equations on each page.

Let me give you a brief example. My engine revs at 38000rpm max. So (rpm)e = 38000 r/min (hpiracing sais 40000 out of the nitro star 18ss but I don''t believe them.LRP z.18 makes 36000 but mine is modified so I''m almost sure that it revs somewhere around 38000 practical). I use 23T pinion (2nd gear) and 43T spur. So T1=23 and T2=43. Also the final gears are Tf1=13 and Tf2=38. Also the wheel radius of my current wheels (rim+tire) is 3.4cm. So Rw=3.4

Vmax = 0.003768*((T1*Tf1*Rw)/(T2*Tf2))*(rpm)e => Vmax=0.003768*((23*13*3.4)/(43*38))*38000 => Vmax = 89.0825 [Km/h]

To convert that in mph: Vmax[mph] = 0.62*Vmax[km/h] => Vmax[mph] = 0.62*89.0825[km/h] => Vmax[mph] = 55.23mph

Ok, I finally get it [8D]

Another example: Fot the same car (same max rpm, same final gear ratio) What gearing do I need to get to 70mph if I''ve already found bigger foamies (larger radius->more top speed), let''s say with 4cm radius (the ones that miami guys use)??? (searching for the T1/T2 ratio)

Solution:
We have to calculate backwards. With easy modifications I rebuild the equation: Vmax[mph]=0.62*Vmax[km/h] => Vmax[km/h] = 70mph/0.62 = 112.9km/h

(T1/T2) = (Vmax*Tf2)/(0.003768*(rpm)e*Tf1*Rw) => (T1/T2) = (112.9*38)/(0.003768*38000*13*4) => (T1/T2) = 0.57621

So for the current T1 pinion gear (23T) I need T2=39.916T wich means that using the HPI 39T spur gear will boost the car above 70mph!!!

FEAR TRAXXAS!!!

...Or a could just save time and buy a schumacher fusion and completely destroy you [>:]

Till the first corner ...then the fusion yould be somewhere out of the track...and the RS4 still running. And if the fusion managed to corner the RS4 corners 3 times faster!!!

yo thanks man i have been looking for something similar to get a top speed of my OS 18TM, it looks pretty simple actually.!

No problem! I like physics...brain training...

man, is this what ill have to look forward to in AP physics? [:-] thanks for making it though, ill re read it and try to understand.

Physics is easy once you open your mind and realise that you can do magic things with it! It''s really several times easier than it looks!

Gynaikas! Send me your email in a PM as I have a spreadsheet for you. Its to calulate the HP at the back wheel using an inertia roller type dyno. As you love phisics you can check the calcs

Cheers

Gynaikas, Superb work! Are you a descendent from Socrates? [8D] I appreciate all your work and I love physics, being a nuclear physicist and af former NASA scientst.
For all the RC'ers without any Physics knowledge, I suggest you pick up an introductory/elementary physics text fro a local library and learn te basic principles of Nature (physics) and why things work the way they do. It will help you enjoy your great hobby even more with the understanding of the underlying physics. Math is the language we use to understand the mechanisms of the nature. RC cars, radios are no different. THey are designed at the drawing board using simple laws of Physics such as Inertia, momentum, energy transfer, rotational dynamics, laws of thermodynamics, laws of electricity and magnetism. As far as materials are concerned, the strengths and structural integrity of a chassis and all connected parts have calculated load/torque distributions that keep the car balanced at high speeds as well as tight cornering. So, Gyanikas has contributed well to this forum with the basics of physics on how torque is transferred from Engine to the drivetrain. He has done a remarkable job in defining terminology and deriving the equations to explain in detail as to what variables would yield the desired results. FYI, guys, you will definitely need to learn Gynaika''s language Greek to understand Quantum mechanics...

The Socrates thing passed my mind aswell.

Good work GYNAIKAS.

I think once you brain train to the physics way of thinking, its simple. Because thats what physics is about. As simple as you can get. The fundamental laws of nature.

Thank you VERY VERY much for your words. I don''t know what to say! It''s always my pleasure to help RCr''s! It''s really an honor for me that a great scientist spent some time to read my humble papers!

As you may have seen I also work on 3 other projects. A receiver battery led indicator (ready), a tire warmer controller with 4 blanket-type warmers (in progress) and a AVCS control system (D-box gyro, also in progress).

Yesterday I had a great idea of making something that every rc car driver would like to have on his car and it''s not on sale yet (at least I haven''t found anyone producing such a thing). It''s a surprize but I''ll give you a clue... it measures something [8D]

I think this thread should become a sticky... well done gynaikas [sm=thumbs_up.gif].. i am a first year university physics student, and one of the reasons i love this hobby so much is that i see the not only the good fun aspect, but also the application of most of the theoretical knowledge in physics to produce something so cool as RC! This really helps and if we can take some time out to learn the fundamentals it takes out of the guess work some of us do especially when it comes to gearing etc...

I think we should have some more tutorial type threads goin on... spreading knowledge always helps... from what ive gathered there are many engineers and scientists who are hobbyists and can really spread some light. If we all pool our resources we can improve the quality of the rc experince to newcomers.

If i am not mistaken this is not your first academic type post ... i think your posted some diagram for some lighting set up using a 3rd channel on your transmitter??

Actually It's the 3rd. The first one was the simple light circuit controlled from the 3rd channel as you said and the sevond one was an entire analysis on the difference between nitro engines and electric motors (torque - rpm diagrams). Unfortunately the 2nd was a huge post in someone elses's thread...I think the initial topic was something about putting a 0.9 engine on a 1:10 car...or something like that...

I've also done many other calculations and simple formula applications at several threads.
Thank you for your words! I'm glad that the "scientific RC" club is getting bigger!!! [8D]

I agree. This forum needs more facts and less which is faster fusion or 4tec type threads.

I vote for a restricted tech or reference section were you can go to research all areas of rc cars, like an encyclopedia. Information like what GYNAIKAS has provided could be submitted to the moderator, and if approved, added to the tech section.

Gynaikas, you are funny bro, its obvious you are a faithful R/Cist...!

Thanks for the info! I started reading the first sentence and it gave me a headache and besides it takes too much time of my prono time, lol.

So many posts erased??? Anyway here's what I posted:

WOW many posts here. First of all the torque that comes from the formula HP/rpm is not constant...it changes while you move from 0 - max rpm. HP changes too so that's why you see 2 completely different diagrams on the dyno screen. And that torque is the torque in the crankshaft of the engine that it stansfered directly to the pinion wich is connected tigtly to the crankcshaft via the clutch (FOXY: I don't add clutch and tire friction coefficients cause then the thing becomes REALLY complicated and only Matlab can help you to make graphic representation of all the dynamic variables. Practicly when you reach top speed the tires don't slip at all and the clutch is also 100% engaged so we skip these coefficients cause practicly they affect the final result only by 4-5% maximum. Now, all the other frictions from bearings, gears and also the air resistance are compacted in the engine's max practical rpm.So when we say that max theoritical rpm is 40k I calculate using 37k cause engine doesn't roll free and never reaches the theoritical number when car runs.)
So Qe=Qp cause they are as "one part" and they spin with the same angular velocity. So If you divide it with the pinio gear's radius you get different force amount for different radius.

ziggy12345: If I remember well these are the specs that Sirio had officialy anounced (with dyno sheet included) for the Siro .21 lamberto collari edition that I used on my ex EVOLVA. Now it's sold so I no more have the sheet to post . I had posted pics of it 1 year ago (maybe more) but it's somewhere in this forum for sure.

PS1) Foxy is right about the educational standard here in Greece. And I could easily add friction air resistance etc to these "simplified" equations. But it would be worthless cause noone can measure the values needed for the coeficients setting without proper instruments. And Foxy my friend I REALLY appreciate your words! Thanks!

PS2) Today I'm leaving on easter holidays with no internet available (thank God I'll stay away from technology for a while!!! I need spiritual recharge!!! LOL) and I'll be back in 2 weeks froms today! So pm or mail me and If I get a chance I'll check my mails. Have a nice time here and keep up the good work!

CU ALL SOON!!! [8D][8D]