This sounds like an interesting challenge!!

Since my exams finish next week that should leave plenty of time to get Whirlwind up and running so I can have a go at getting Seraphim OOTA

Anyway here are the stats for Whirlwind

Weight ~13.6kg
Length ~40cm
Width ~50cm
Height ~ 20cm
Weapon- FP Flipper with a 60mm bore, 80mm Stroke ram fired by a burket with a 9oz painball bottle for the buffer tank.
Drive: 2x 50:1 MFA motors running at 24v with 80mm diameter wheels
Speedo: Scorpion XL
Batteries: 3700mAh 24v Ni-Mh
Radio- DX6i with AR500 rx
Armour- 3mm Aluminium frame with 10mm Nylon/HDPE base with 5mm Welded HDPE armour
Notes: Should be ready for RIAT

Also here is my brothers replacement for Shockwave

Name: Heatwave
Weight ~13.6kg
Weapon- FP flipper with a 45mm bore, 50mm stroke ram, fired by a burket with a buffer.
Drive: 2x 18v Drills running at 24v with 75mm wheels
Speedo: Scorpion XL
Batteries: 3700mAh 24v Ni-Mh
Radio: DX5e with BR6000 rx
Armour 5mm HDPE on 3mm Aluminium frame
Notes: Should be ready for Guildford