06 Oct 2022
 | 06 Oct 2022
Status: a revised version of this preprint is currently under review for the journal GI.

Design and Performance of the Hotrod Melt-Tip Ice-Drilling System

William Colgan, Christopher Shields, Paval Talalay, Xiaopeng Fan, Austin P. Lines, Joshua Elliott, Harihar Rajaram, Kenneth Mankoff, Morten Jensen, Mira Backes, Yunchen Liu, Xianzhe Wei, Nanna B. Karlsson, Henrik Spanggård, and Allan Ø. Pedersen

Abstract. We introduce the design and performance of a melt-tip ice-drilling system designed to insert a temperature sensor cable into ice. The melt tip is relatively simple and low cost, designed for a one-way trip to the ice-bed interface. The drilling system consists of a melt tip, umbilical cable, winch, interface, power supply, and support items. The melt tip and the winch are the most novel elements of the drilling system, and we make the hardware and electrical designs of these components available open access. Tests conducted in a laboratory ice well indicate that the melt tip has an electrical energy to forward melting heat transfer efficiency of ~35 % with a theoretical maximum penetration rate of ~12 m/hr at maximum 6.0 kW power. In contrast, ice-sheet testing suggests the melt tip has an analogous heat transfer efficiency of ~15 % with a theoretical maximum penetration rate of ~6 m/hr. We expect the efficiency gap between laboratory and field performance to decrease with increasing operator experience. Umbilical freeze-in due to borehole refreezing is the primary depth-limiting factor of the drilling system. Enthalpy-based borehole refreezing assessments predict refreezing below critical umbilical diameter in ~4 hours at -20 ˚C ice temperatures and ~20 hours at -2 ˚C. This corresponds to a theoretical depth limit of up to ~200 m, depending on firn thickness, ice temperature and operator experience.

William Colgan et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gi-2022-18', Anonymous Referee #1, 04 Nov 2022
    • AC1: 'Brief Reply on RC1', William Colgan, 10 Nov 2022
    • AC2: 'Authors' reply to RC1', William Colgan, 28 Feb 2023
  • RC2: 'Comment on gi-2022-18', Kris Zacny, 19 Dec 2022
    • AC3: 'Authors' reply to RC2', William Colgan, 28 Feb 2023
  • RC3: 'Comment on gi-2022-18', Anonymous Referee #3, 05 Feb 2023
    • AC4: 'Authors' reply to RC3', William Colgan, 28 Feb 2023
  • EC1: 'Comment on gi-2022-18', Andrew Wickert, 08 Feb 2023
    • AC5: 'Authors' reply to EC1', William Colgan, 28 Feb 2023

William Colgan et al.

Data sets

Hotrod melt-tip ice-drilling system Colgan, W., C. Shields, A. Lines, J. Elliot and H. Rajaram

William Colgan et al.


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Short summary
We describe a new drill for glaciers and ice sheets. Instead of drilling down into the ice via mechanical action, our drill melts its way down into the ice. Our goal is simply to pull a cable of temperature sensors on a one-way trip down to the ice-bed interface. Under laboratory conditions, our melt-tip drill has an efficiency of ~35% against a theoretical maximum penetration rate of ~12 m/hr. Under field condition, our efficiency is just ~15 %. Clearly room for improvement!