2010/02/16

Army motorcycles

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I have a love for Enduro motorcycles (the "sport" versions, not so much the "travel" or "cruise"-oriented versions) and a motorcycle driving license (though sadly no actual Enduro at the moment).

It was fun to think a bit about the optimum army motorcycle and I'd like to share my thoughts (that does obviously happen at times ;-) .


Enduros have a small thirst for fuel, great off-road agility and they can drive past traffic jams.
Their disadvantages are as obvious; non-stellar durability, easily fatigued driver, no weather or other protection, low payload (both in volume and weight).


The classic roles are for military police (traffic control) and couriers and both roles are pretty much consensus applications. The trust in radio communication and the high cost of personnel has lead to a diminished role of motorcycle couriers during the last years - that was probably no good move.

I did recently read an article about military motorcycle trials in 1938. Very light motorcycles excelled on the short and demanding track, handled by expert motorcyclists.
The same category of lightweight motorcycles with small engine volume was a near-total disaster only three years later when many if not most became almost useless after a few weeks or months of continuous campaigning on the poor roads of Eastern Europe. The much more robust heavier motorcycles that had no chance to excel on a small proving ground showed their true value.

We should remember these experiences and take into account the huge demands of actual wartime use on motorcycles (and all other equipment). The relatively short peacetime exercises will never tell us everything that military history has to offer.

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About the technology for a dream army motorcycle:

(1) Fuel

Motorcycles very rarely use diesel fuel, the standard fuel of modern armies. Diesel engines are hard to come by for motorcycles, but I consider them to be a very desirable component for logistical reasons (fuel commonality with all other army vehicles in the field). It has already been done.






A road range of 1,000 km would be desirable from a logistical point of view, but the extra weight would likely be too troublesome during off-road driving. A simple flexible tube would instead allow a motorcycle driver to get some diesel fuel from a truck, and the truck driver would hardly notice the loss.

(2) Engine in general

Small volume engines are light and allow for light Enduros with good agility. Higher volume engines can have more power, allow for more payload and tend to be better on very soft ground. An additional problem is the demand for longevity. This means that military motorcycles at times need to be de-rated. A durable 600 ccm military motorcycle may have as little power as a civilian high-end 300 ccm motorcycle.
The best compromise for military motorcycling would probably be about 450 ccm with a normal engine, but a derated diesel engine (or a custom-developed diesel engine) would likely have less hp/kg and likely shift the best compromise even more, maybe to 600 ccm (the M1030M1 has 584 ccm).

Electric starter with kick start backup; good idea.

(3) Power transmission aft

Most motorcycles use a chain for power transmission. That requires much maintenance and is generally not a good idea for a motorcycle that's going off-road very often and for extended periods. A shaft drive design (with gearbox) would be much better in regard to maintenance and impervious to dirt. The design of a long-life gearbox is a challenge, though.

(3) Power transmission front

A two wheel drive (2x2, 2WD) is a rarity for motorcycles, but it should be considered for an army motorcycle. The additional cost and weight is probably worth it because it makes driving and especially negotiating obstacles much easier and even safer. The hydraulic power transmission seems to be the front-runner concept at the time. I would therefore want to see contenders with a non-permanent hydraulic powered front wheel in a competition for a military motorcycle.





(4) Motorcycle stand

This needs to be reliable even on soft ground; a large contact area for a low ground pressure is a necessity.

(5) Battery and fuel system

Both need to be designed for reliable function after lying on the side. Many normal motorcycles have trouble starting again after having been on their sides for a while.

(6) All weather design

Modern motorcycles are as much toys for leisure as tools for travel and commuting. The relevance of poor weather motorcycling has dropped during the past decades and the motorcycle designs have become accordingly less able to cope with poor road conditions (at least compared to the advancing technology limits).
Likewise, modern motorcycle designs are rarely designed for use during winter.
This problem extends to items such as the helmet, as some helmets have permanently open ventilation openings that are no good idea for poor weather.
A military motorcycle would need to be prepared for poor and cold weather.

(7) Longevity

A new military motorcycle would be in service for 20-30 ears, much longer than a typical civilian one. This causes different requirements for the longevity of components such as seals, as well as protection against rust (or the use of non-rusting materials, such as aluminium).

(8) Extras

An army Enduro should have storage boxes for personal equipment and a rack for the driver's carbine (acessible even if the motorcycle is lying on its side).

It should also have equipment that helps with self-recovery if it's really stuck (exhausted drivers may be unable pull their Enduro out on their own) such as a simple rope that could use the front axle as a winch.

Another interesting extra would be some kind of folding aluminium rack for the crossing of obstacles such as drainage ditches (which can be too steep for a motorcycle).

A box for a camouflage net is a simple necessity in my opinion.

The quite common protective hand guards should be installed for protection against branches and to reduce the problem of cold hands (less airflow) in winter.

A roll chart holder or navigation computer is a necessity because quick and reliable navigation is one of the keys to success in courier missions.

(9) Wheel design

There are basically two options; Enduro wheels (with precautions against a rapid loss of pressure) or much wider, smaller diameter wheels. The latter offer some advantages, but seem to be ill-suited for high speeds. I would prefer the former because most army motorcycling would still happen on roads and there's no compelling case for the unorthodox wheels for couriers or MPs.
Designs for tires that accept perforation quite well are available and should be used.

(10) 'Silent' exhaust system

An army motorcycle cannot be too silent. The exhaust and engine itself can be designed to allow for an unusually low noise level.

(11) Overall low maintenance design

Low and simple maintenance, 'nuff said.

(12) Accessories

A combined ballistic & crash protection helmet is an obvious choice, and several such models are available. The German Schuberth helmet with combined crash and ballistic protection has been phased out of service because it didn't meet a new norm (red tape).
Some form of radio receiver/headphones would make sense; the driver should be able to hear radio traffic permanently.

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In the end, such a not-off-the-shelf design would probably cost twice as much as a conventional motorcycle even if bought in a large batch. It may be possible to justify that with performance and longevity.
It's obvious that air forces and navies would not need such a dedicated army motorcycle if they have a real need for motorcycles at all.

 
S O

edit 2014: The old Swedish Husqvarna army motorcycle with its deep snow capability (side skis) and automatic transmission (for soldiers without experience with motorcycles) is quite an inspiration as well. It's a light motorcycle (250 cc), and thus relatively easy to handle as well.
I'd also add the easy attachment of a motorcycle to a truck as a criterion if I would write this blog post today.

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