diff --git a/libraries/AP_Common/AP_ExpandingArray.cpp b/libraries/AP_Common/AP_ExpandingArray.cpp
new file mode 100644
index 0000000000..661ca56390
--- /dev/null
+++ b/libraries/AP_Common/AP_ExpandingArray.cpp
@@ -0,0 +1,66 @@
+/*
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "AP_ExpandingArray.h"
+
+AP_ExpandingArrayGeneric::~AP_ExpandingArrayGeneric(void)
+{
+    // free chunks
+    for (uint16_t i=0; i<chunk_count; i++) {
+        free(chunk_ptrs[i]);
+    }
+    // free chunks_ptrs array
+    free(chunk_ptrs);
+}
+
+// expand the array by specified number of chunks, returns true on success
+bool AP_ExpandingArrayGeneric::expand(uint16_t num_chunks)
+{
+    // expand chunk_ptrs array if necessary
+    if (chunk_count + num_chunks >= chunk_count_max) {
+        uint16_t chunk_ptr_size = chunk_count + num_chunks + chunk_ptr_increment;
+        chunk_ptr_t *chunk_ptrs_new = (chunk_ptr_t*)realloc(chunk_ptrs, chunk_ptr_size * sizeof(chunk_ptr_t));
+        if (chunk_ptrs_new == nullptr) {
+            return false;
+        }
+
+        // use new pointers array
+        chunk_ptrs = chunk_ptrs_new;
+        chunk_count_max = chunk_ptr_size;
+    }
+
+    // allocate new chunks
+    for (uint16_t i = 0; i < num_chunks; i++) {
+        uint8_t *new_chunk = (uint8_t *)calloc(chunk_size, elem_size);
+        if (new_chunk == nullptr) {
+            // failed to allocate new chunk
+            return false;
+        }
+        chunk_ptrs[chunk_count] = new_chunk;
+        chunk_count++;
+    }
+    return true;
+}
+
+// expand to hold at least num_items
+bool AP_ExpandingArrayGeneric::expand_to_hold(uint16_t num_items)
+{
+    // check if already big enough
+    if (num_items <= max_items()) {
+        return true;
+    }
+    uint16_t chunks_required = ((num_items - max_items()) / chunk_size) + 1;
+    return expand(chunks_required);
+}
diff --git a/libraries/AP_Common/AP_ExpandingArray.h b/libraries/AP_Common/AP_ExpandingArray.h
index b7296ba7ec..f7c343fd3d 100644
--- a/libraries/AP_Common/AP_ExpandingArray.h
+++ b/libraries/AP_Common/AP_ExpandingArray.h
@@ -16,6 +16,9 @@
 /*
  * ExpandingArray class description
  *
+ * ExpandingArrayGeneric implements most of the required functionality and is type agnostic allowing smaller overall code size
+ * ExpandingArray<T> is the template and implements the small number of type specific methods
+ *
  * Elements are organised into "chunks" with each chunk holding "chunk_size" elements
  * The "chunk_ptrs" array holds pointers to all allocated chunks
  *
@@ -38,96 +41,69 @@
 
 #include <AP_Common/AP_Common.h>
 
-template <typename T>
-class AP_ExpandingArray
+class AP_ExpandingArrayGeneric
 {
 public:
 
-    AP_ExpandingArray<T>(uint16_t elements_per_chunk) :
+    AP_ExpandingArrayGeneric(uint16_t element_size, uint16_t elements_per_chunk) :
+        elem_size(element_size),
         chunk_size(elements_per_chunk)
     {}
 
-    ~AP_ExpandingArray(void)
-    {
-        // free chunks
-        for (uint16_t i=0; i<chunk_count; i++) {
-            free(chunk_ptrs[i]);
-        }
-        // free chunks_ptrs array
-        free(chunk_ptrs);
-    }
+    ~AP_ExpandingArrayGeneric(void);
 
     /* Do not allow copies */
-    AP_ExpandingArray<T>(const AP_ExpandingArray<T> &other) = delete;
-    AP_ExpandingArray<T> &operator=(const AP_ExpandingArray<T>&) = delete;
+    AP_ExpandingArrayGeneric(const AP_ExpandingArrayGeneric &other) = delete;
+    AP_ExpandingArrayGeneric &operator=(const AP_ExpandingArrayGeneric&) = delete;
 
     // current maximum number of items (using expand may increase this)
     uint16_t max_items() const { return chunk_size * chunk_count; }
 
-    // allow use as an array for assigning to elements. no bounds checking is performed
-    T &operator[](uint16_t i)
-    {
-        const uint16_t chunk_num = i / chunk_size;
-        const uint16_t chunk_index = i % chunk_size;
-        return chunk_ptrs[chunk_num][chunk_index];
-    }
-
-    // allow use as an array for accessing elements. no bounds checking is performed
-    const T &operator[](uint16_t i) const
-    {
-        const uint16_t chunk_num = i / chunk_size;
-        const uint16_t chunk_index = i % chunk_size;
-        return chunk_ptrs[chunk_num][chunk_index];
-    }
-
     // expand the array by specified number of chunks, returns true on success
-    bool expand(uint16_t num_chunks = 1)
-    {
-        // expand chunk_ptrs array if necessary
-        if (chunk_count + num_chunks >= chunk_count_max) {
-            uint16_t chunk_ptr_size = chunk_count + num_chunks + chunk_ptr_increment;
-            chunk_ptr_t *chunk_ptrs_new = (chunk_ptr_t*)realloc(chunk_ptrs, chunk_ptr_size * sizeof(T*));
-            if (chunk_ptrs_new == nullptr) {
-                return false;
-            }
-
-            // use new pointers array
-            chunk_ptrs = chunk_ptrs_new;
-            chunk_count_max = chunk_ptr_size;
-        }
-
-        // allocate new chunks
-        for (uint16_t i = 0; i < num_chunks; i++) {
-            T *new_chunk = (T *)calloc(chunk_size, sizeof(T));
-            if (new_chunk == nullptr) {
-                // failed to allocate new chunk
-                return false;
-            }
-            chunk_ptrs[chunk_count] = new_chunk;
-            chunk_count++;
-        }
-        return true;
-    }
+    bool expand(uint16_t num_chunks = 1);
 
     // expand to hold at least num_items
-    bool expand_to_hold(uint16_t num_items)
-    {
-        // check if already big enough
-        if (num_items <= max_items()) {
-            return true;
-        }
-        uint16_t chunks_required = ((num_items - max_items()) / chunk_size) + 1;
-        return expand(chunks_required);
-    }
+    bool expand_to_hold(uint16_t num_items);
 
-private:
+protected:
 
+    const uint16_t elem_size;   // number of bytes for each element
     const uint16_t chunk_size;  // the number of T elements in each chunk
     const uint16_t chunk_ptr_increment = 32;    // chunk_ptrs array is grown by this many elements each time it fills
 
-    typedef T* chunk_ptr_t;     // pointer to a chunk
+    typedef uint8_t* chunk_ptr_t;   // pointer to a chunk
 
     chunk_ptr_t *chunk_ptrs;    // array of pointers to allocated chunks
     uint16_t chunk_count_max;   // number of elements in chunk_ptrs array
     uint16_t chunk_count;       // number of allocated chunks
 };
+
+template <typename T>
+class AP_ExpandingArray : public AP_ExpandingArrayGeneric
+{
+public:
+
+    AP_ExpandingArray<T>(uint16_t elements_per_chunk) :
+        AP_ExpandingArrayGeneric(sizeof(T), elements_per_chunk)
+    {}
+
+    /* Do not allow copies */
+    AP_ExpandingArray<T>(const AP_ExpandingArray<T> &other) = delete;
+    AP_ExpandingArray<T> &operator=(const AP_ExpandingArray<T>&) = delete;
+
+    // allow use as an array for assigning to elements. no bounds checking is performed
+    T &operator[](uint16_t i)
+    {
+        const uint16_t chunk_num = i / chunk_size;
+        const uint16_t chunk_index = (i % chunk_size) * elem_size;
+        return (T &)(chunk_ptrs[chunk_num][chunk_index]);
+    }
+
+    // allow use as an array for accessing elements. no bounds checking is performed
+    const T &operator[](uint16_t i) const
+    {
+        const uint16_t chunk_num = i / chunk_size;
+        const uint16_t chunk_index = (i % chunk_size) * elem_size;
+        return (const T &)(chunk_ptrs[chunk_num][chunk_index]);
+    }
+};