Aerospace & Defense Technology - December 2023 - 32

Tech Briefs
tems, which enables a more structurally
efficient aircraft. The majority of the aircraft's
exterior is composite, in addition
to the proprotor blades and many of the
internal structural components. In order
to increase payload, range, airspeed, and
other critical mission capabilities, it is
likely that the U.S. Army and aircraft
manufacturers will begin incorporating
and preparing to maintain a much greater
number of these types of structures on
future aircraft.
This work was performed by Bryan
M. Steiner, Jared R. Peltier, Stephen J.
Janny, and Brian A. Cerovsky for the
U.S. Army Combat Capabilities Development
Command. For more information,
download the Technical Support
Package (free white paper) at
mobilityengineeringtech.com/tsp
under the Materials section.
Assessment of Noncommercial Icing Prediction
Capabilities for Army Applications
Ice prediction capabilities for Unmanned Aerial Systems (UAS) is of growing interest as UAS designs
and applications become more diverse. This report summarizes the current state-of-the-art in modeling
aircraft icing within a computational framework as well as a recent U.S. Army DEVCOM AvMC
effort to evaluate ice prediction models for current use and future integration into the Computational
Research and Engineering Acquisition Tools and Environments (CREATE) Air Vehicle (AV) framework.
U.S. Army Combat Capabilities Development Command, Redstone Arsenal, Alabama
H
istorically, smaller Unmanned Aerial
Systems (UAS), such as Class 2 RQ-1B
Raven and Class 3 RQ-7Bv2 Shadow, have
been restricted to not be approved to fly in
icing conditions under the assumption
that any ice accretion would cause an
unacceptable risk of loss of the aircraft.
However, interest exists in better understanding
potential icing accretion on UAS
to determine if less extreme icing conditions
could result in only partial degradation
and not total loss of the vehicle for the
purpose of expanding approved flight
envelopes. Icing accretion can be tested
during a flight test, which is considered
unacceptable due to lack of controlled conditions
and risk to the UAS or in a controlled
experiment, by using wind tunnel
testing to evaluate a single icing condition.
Cryogenic wind tunnel tests, such as those
conducted at the National Aeronautical
and Space Administration (NASA) Glenn
Icing Research Tunnel (IRT), Cleveland,
OH, as shown in figures 1 and 2, are prohibitively
expensive and time consuming
to evaluate a wide array of icing conditions
on multiple UAS. The ability to simulate
aircraft icing using computational methods
permits evaluation across a number of
vehicles and icing scenarios for a fraction
of the cost and time.
The aerospace scientific community has
recently developed interest in ice prediction
capabilities within a computational
framework. In 2021, the first American
32
Figure 1: The common research model in IRT was
involved in this research project.
Institute for Aeronautics and Astronautics
(AIAA) Ice Prediction Workshop was held
in conjunction with the AIAA Aviation
Forum [2]. Twenty participants from academia,
industry, and government evaluated
ice accretion on Two-Dimensional (2-D)
and Three-Dimensional (3-D) geometries
where experimental ice shapes were publicly
available by using a wide range of solvers
to assess the state-of-the-art in icing
prediction tools. Kestrel and Helios, the
Computational Research and Engineering
Acquisition Tools and Environments (CREATE)
Air Vehicle (AV) simulation tools for
fixed-wing and rotorcraft evaluation, do
not have ice prediction capabilities.
DEVCOM AvMC conducted an assessment
of NASA-developed icing predicmobilityengineeringtech.com
Figure
2: Ice accretion on a powered force model
rotor in IRT.
tion codes for potential application to
Army UAS aerodynamic modeling predictions.
Current capabilities are considered
to be lacking for DEVCOM AvMC
use due to 2-D formulation and a lack of
CFD-based streamlined iterative solution
methods. NASA is planning to
address these issues with the public
release of GlennICE. At this time, Commercial
Off-The-Shelf (COTS) codes are
considered to be the best path forward.
This work was performed by Amanda
G. Kolpitcke, Kevin C. Losser, and Zachary
M. Hall for the U.S. Army Combat
Capabilities Development Command.
For more information, download the
Technical Support Package (free white
paper) at mobilityengineeringtech.
com/tsp under the Materials category.
Aerospace & Defense Technology, December 2023

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Aerospace & Defense Technology - December 2023

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