Buggy-Truggy hybrid with 8s1p A123

[othello]

After having fun with a BL-buggy and then with a BL-truggy, i wanted to have the agility of a buggy with the offroad capabilities of a truggy. So, I took both axles and the center diff of my Robitronic Mantis truggy and bolted them on the Robitronic Protos buggy chassis. I quickly reconfigured my 5s1p A123 battery packs to 4s1p so that i could run my Neu 1512/2Y (1400kv) with 8s1p in the 31000rpm region for which my gearing was optimised (I did run a 1515/2Y 1100kv with 10s1p A123 in my truggy). I made some basic battery trays and mounting plates for the eagletree logger and the Jazz 55-10-32 ESC. Balance between right/Left and front/rear is very equilibrated with this config. It wheighs 9.7lbs (4.4Kg) ready to run. Overall gearing is 1:14 with 13 tooth pinion or 1:13 with a 14 tooth pinion. No easy task for a "small" Neu 1512.

Some pics with body




Some pics without body (sorry, not as clean as most of the conversion i saw here. But it works ;-)




After 19 runs on asphalt and a small forest track i'm very happy with its performance and it does seem that it can combine the advantages of a buggy and a truggy. Due to its buggy wheelbase it is more agile and handles tighter turns better then with its truggy chassis. Due to its truggy axles and tires it stays more stable on bumpier tracks. The Neu 1512 has more then enough power (max peak at 1850 Watt so far) to wheelie the car, but there is still too much unloading to the front tires with 30000cps diff oil in the center diff. I think i'll have to use 50000cps. Here is an eagletree graph of one of my last runs with a 13 tooth pinion.


. runtime hovers around 7 minutes
. the motor reaches around 31000rpm (calculated top speed around 40mph/65kmh)
. 18A or 390 Watts on average
. Mostly between 45-65A peaks while accelerating (loose surface with low grip)
. Up to 1500 Watt peak on this run (1850 Watt with a 14 tooth pinion and better grip)
. Motor temperature reaches between 125-143°F (55-62°C) with outside temperatures between 65-80°F (18-26°C). Both fans do run a bit too slow on 8s A123. After regearing the car to 1:16,8 i will be able to run it on 10s1p A123, reducing amps and improving the fans airflow: so it should run cooler.

Video: http://194.158.136.73/ds/rc/protis_run05_850k.wmv

This is a very short clip of it running (with a 14 tooth pinion). Sadly i hit the root of a tree after a minute. The camera man did not really have some time to familiarise himself to the cam and the moving vehicle. More videos to come within a few days.

What do you guys think?