Mode Zero

The easiest way to manage lipos in old setups is to use one of those cheap lipo voltage alarms.
Just a few dollars from Hobbyking or Banggood & they emit a loud beep once you hit 3.4v per cell. Plugs into the balance lead.
You hear it & throttle down to land & the voltage will come back up around 3.6v per cell.

Works a charm, cheap, easy & effective.

Al

I'll second Al's suggestion. Back in the early days of drones that's exactly what we used to stop them falling out of the sky.!
Make sure you get the loud ones with 2 piezo Sounders on though and use your countdown timer on the tx as back up.

Shaun.

The units shown also protect against overcharge.

Further investigation has revealed the motor is an Astro 25 which Astro info google found for me says 14 cells which is 16.8v so looks like I will try a 4s Lipo, I had already tried taxing in the garden with a 3s and she struggled with the grass but on the tarmac lane at the end of the drive she raced away, hampered with the castoring tail wheel not helping the steering! My test pilot is away so I may take the risk of a test flight myself I have bought some of the voltage warning buzzers as Al's suggestion and shall use one and be careful, while I have a fair few 3s, I only have a couple of 4s! If successful I will have a look at one of the BMS thingies! I am attaching the Astro manual, which might be of interest to others
Gary, your money is safe, Porterfield Collegiate she is, not sure if plan or kit.

Test flew her today at the airport (local farmers air strip), flew a treat. plenty of power and used approx. 15% of the 4400 4s battery for 2mins, flight was curtailed as a hatch decided to go freefall but luckily her indoors was with me and found it easily by the time I landed, fortunately the maize by the side of the strip less then a foot high!