Some aeromedical groups are quite aware of the O2-alcohol matters, oddly they aren't universally stupid, but mistakes can happen. O2 bottles are invariably added to any Air Ambulance aircraft, and functionally that is a act of life. For this aircraft, they were about where the damage would suggest.
The departure is about 1:50 after dark, birds are not highly likely but do occur.
VR for this aircraft on the day... (heavy, warm not hot) is a F0 takeoff, and 152 KIAS. TODR is around 8800'.
STAB trim. the CG would be around 24%, and anyone who has flown WWs and similar is familiar with the rotate characteristics, which are, interesting, even with the correct trim setting. (any WW with a load of people will have a fwd CG, fuel changes that slightly but not enough to bother about). That is about -2.8 to -3 on the stab. That is about what the accident aircraft appears to show. The trim is about the right spot, so long as the aircraft is within the trim envelope of the plane. If it is outside at the forward end of the envelope (24% is about the exact fwd limit) then the rotate will be a laborious and long time happening.
O2 probably didn't start the problem but is a perennial favorite once things go into the rough. This plane would have had between 6500L and 10000L of medical O2 onboard. O2 is great in small doses. O2 is a necessity for any ambulance task unless the patient is already in the binary state of being dead.
Doors on the WW in this case would not have been compromised. The design is a great bit of ingenuity to get a plug door working in a small airframe. Had it been possible to move the lever, it would have shown on the outside of the aircraft. the door was never attempted to be opened, that is how fast it went bad after fire erupted.
Look for feathers around 5000'-6500' down the runway, but that seems like a long shot. given the time. Minimise the amount of C, D, & E bottles that are carried. fixed systems sound safer and are tidier, but O2 is O2, its an oxidiser, that's where the term comes from. It was necessary on the space shuttle, and until there is an alternative to breathing, it is a necessity for ambulance operations as well.
Nomex looks great, and will make zero difference in a conflagration like this.
The airframe itself was fully survivable, the WW is built like a tank, the rupture of the aft fuselage opens up the main and stby fuel boost collector tank outlets to the engines, and that starts a bad day. The fuselage failure forward of the CWT/aft bulkhead is similar to the waterwings effort off YSNF. The passenger compartment was completely survivable other than the fire. They would had more than 6500lbs and up to about 8500l a little shy of full fuel on the day.
Before every takeoff, be it an Airbus, Boeing Learjet GEX, or WW, there are specific decision points to consider. "above ... Kts, we will reject for. ...... ,......, ..... and .... " Those items are not random, they are limited for very good reasons, as often RTO's don't end well.
For the WW, if you enter any takeoff with flaps zero, and give a failure of spoilers/lift dump and anti-skid, you cannot get a performance solution, at any weight. APG does not permit just the spoilers inop for the analysis, but the hint is, that in an RTO, brakes/LIFT DUMP/TR's are absolutely necessary for a successful conclusion. What happened here will be known in full soon enough, but it is a timely reminder to listen to our own briefs and heed the cautions that are in that. In airlines, RTO's get practiced at some level of continuity, still not enough to guarantee crews will achieve the correct actions, and worse, often the everyday procedure of landing compromises the procedures for an RTO... use idle reverse... use this, use that, things that differ from the bad day scenario.
Condolences to all, and for those in Aero Medical, take care out there, inherent risks come with the task.
fly safe.