bertrandsv87

iTrader: (2)

Nice video ! Rccartips, I think 4.7fdr to 4.9fdr should be good with a seriously tuned johnson motor. The Nikko F1 1/10 scale cars I use to run were geared at 4.99fdr with bushings, heavy steel drivetrain, and gear friction like no other, but I could get over 15Minutes with 4200mah nimh packs...

MatsNorway

Nothing beats "DD"

In fullsize cars its common to say that there is a 10% loss in FR cars.
20% for 4WD. (no sources but common estimate)

A lot of it is probably down to the bevel gears in the diff.

Usually its a bit worse on full size cars because they sometimes have the input shaft below senter to save space.

Hypoid gear.


All that said i think the main issue is lack of correct gearing for Mantisworxs

The evolution of brushless has been towards lower Kv and higher efficiency. good example is X11 - X12 to the new X20.

Papi

Main problem of this layout is that you can't simply change pinions. Bevel gears have different angle of teeth for every gear ratio wrong angle means effiiciency loss.

I don't think that bevel gears has much worse efficiency than spur gear (but I agree that hypoid do) as FF with transverse engine have similar efficiency. Loses in fullsize cars are caused by gearbox (5-6 pairs of gears meshed all time, oil resistance) and a helical gears which are quieter but less efficient.

InspGadgt

Aren't those Helical gears?

Papi

Those are hypoid - shaft axles doesn't intersect - it's little similar to worm gear. Helical gears are spur with angled teeths (same for bevels at spiral gears)

rccartips

iTrader: (3)

Guys are you talking about a transmission similar to the Tamiya F201? It is motor to spur + 45 deg angle gear to 45 deg and differential.

I think that is already as efficient as you can get with IRS.

Papi

what about direct drive IRS? I found this

http://www.rctech.net/forum/5912523-post4.html

But I don't know how this non-centered layout will afect handling (ofcourse balanced, not like one on the pictures)

nrtv20

iTrader: (9)

That direct drive IRS is too cool!

nicholasxuu

iTrader: (13)

not enough space for motor(for F1 car) if diff is in the center.
not enough space for suspension if diff is not in the center.

may have enough space for motor with diff in the center, if motor is mounted vertically, similar to shaft drive cars except the center shaft is replaced with a motor.
Then there will be shaft effect(the reason modern touring car use belt drive), and less space for battery, and need special 45degrees angle pinion gear to make it work.

kb525

I was thinking of posting this solution. But as mentioned the motor placement will give it terrible initial accel from the torque motion.

InZane

iTrader: (2)

MantisWorx

iTrader: (28)

Its not the gear ratio man, I have been doing this for a while! and have gone anywhere from 2.4 to 3.2, yes if i go higher it gets out of the turns better but i get my ass handed to me at the end of the straight where the DD cars are running 2.1/2.3 ratios, do the math on how many more RPM's i need to math their speed!!

Here is my DD IRS car, only issue is that i am stuck with a 3.2 FDR which doesnt help me out so the car is just used for MOD now!
http://www.youtube.com/watch?v=HNLt0...9&feature=plcp

Papi

I didn't hear from video , which gearbox are you using? Maybe Tamiya's TB-03 would help (2,44 FDR and Eagle racing make 2 smaller gear ratios) or some CS kits for shaft-drive drift cars.

MantisWorx

iTrader: (28)

ITs a Jammin gearbox but im not worried about converting that car to stock, its great for mod so i am not worried about it.

bertrandsv87

iTrader: (2)

Papi, this IRS direct drive is the best solution so far, but you will probably need to run Shorty lipo packs, and put all electronics on the chassis....