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I was watching the video of the AN 225 unloading at Perth airport this weekend, and it suddenly occurred to me that there are about a zillion rear wheels on the aircraft, yet only 2 nose wheels?

This might make sense in a normal airliner, but in this one, the whole weight of the 117 Tonne generator is passed over the front wheels, as it is unloading?

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    $\begingroup$ note from the first photo that there are 2 nose struts, with 2 wheels each, and from the last photo you see an external ramp supporting some of the weight. Interesting question nevertheless. $\endgroup$
    – Federico
    May 17, 2016 at 6:22
  • $\begingroup$ Yes I suddenly thought of the support on the ramp. But nevertheless, would still take the weight on landing and taxiing? $\endgroup$
    – Brendan Gooden
    May 17, 2016 at 6:29
  • $\begingroup$ Nose wheels are designed to take only a minor part of the weight on ground. The balance required for flight constrains the CoG to be near the main gear also on ground. $\endgroup$
    – Federico
    May 17, 2016 at 6:30
  • $\begingroup$ OK so I'm guessing the cargo would have been secured directly over the wheels in that case? $\endgroup$
    – Brendan Gooden
    May 17, 2016 at 6:34
  • $\begingroup$ Note that maximum take-off weight is 640 t. The main gear needs to support that. The 117 t cargo is quite light compared to that and the nose gear only needs to support it for short while during loading or unloading. $\endgroup$
    – Jan Hudec
    May 17, 2016 at 9:07

2 Answers 2

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The reason An 225 has only two nose landing gears (for a total of four wheels) is that it was developed from An 124 Ruslan, which had pretty much the same arrangement. This works during normal operations as the MLG take up most of the load.

However, for loading/unloading, the wheels are not loaded- the nose landing gear is folded, while a support strut comes out, which provides the necessary support and load carrying capacity, as shown below (thanks to @Federico for finding the image).

Strut

Image from airliners.net

In this image, you can clearly see that the NLG is folded and the weight is supported by the struts.

AN 225

Image from news.yahoo.com

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  • $\begingroup$ @Federico The last image shows the mechanism in quite some detail. Good find :) $\endgroup$
    – aeroalias
    May 17, 2016 at 11:20
  • $\begingroup$ @Federico Added it. Thanks :) $\endgroup$
    – aeroalias
    May 17, 2016 at 11:33
  • $\begingroup$ I assume that the close up of the NLG/support strut is from the right side of the plane, looking forward? $\endgroup$
    – FreeMan
    May 17, 2016 at 11:58
  • $\begingroup$ @FreeMan I think its the other way around- from the port side looking into the cargo hold; you can compare with the folded landing gear in the second image. $\endgroup$
    – aeroalias
    May 17, 2016 at 12:00
  • $\begingroup$ Ah, yes, thank you @aeroalias, I see it now. The green structure is part of the ramp folded up. I kept picturing that as the gear bay with some very large doors (which I realize now I magically couldn't see anywhere). $\endgroup$
    – FreeMan
    May 17, 2016 at 12:03
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When an aircraft lands, the nose wheel remains elevated, and the main wheels touch down first. This results in a considerable impact on the runway as all of the weight of the aircraft hits the ground. In order to minimise the impact, and prevent damage to the runway, larger aircraft tend to have multiple bogeys on the main wheels to distribute the weight over a larger surface area.

Due to the sheer size, and unique mission of the An-225, it features a number of wheels in order to maximise the weight distribution on the runway surface, allowing it to carry a greater weight, and operate from smaller airports with weaker runways.

The nosewheel does not suffer from this problem, as the landing impact is much softer due to the main wheels taking most of the weight.

Interesting aside: The A320 can be purchased in both a single-pair and dual-pair main wheel configuration. So far, Indian Airlines (now part of Air India) are the only airline to operate the dual-pair main-wheeled A320, as the standard of runways is not as good in India, and therefore they can serve airports they otherwise wouldnt be able to do. enter image description here

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  • $\begingroup$ I've got to say, I haven't been able to find any reference to a single-nose-wheel A320 configuration, and your picture looks like it could be 1 or 2 wheeled. Do you have a better picture to show a single-wheel nose gear A320? We even have an answer here at Aviation.SE showing the A32x family all have 2-wheeled nose gear. $\endgroup$
    – FreeMan
    May 17, 2016 at 16:05
  • $\begingroup$ @FreeMan - I was referring to the main gear. $\endgroup$
    – Gavin Coates
    May 17, 2016 at 18:41
  • $\begingroup$ To clarify - I was referring to single-pair, and dual pair, main gear. I've edited to clarify that. $\endgroup$
    – Gavin Coates
    May 17, 2016 at 18:48
  • $\begingroup$ Even Air India ordered later models of the A320 with single-pair main gears. $\endgroup$
    – Peter Kämpf
    May 17, 2016 at 19:25
  • $\begingroup$ I don't think this really answers the question, but interesting fact about the A320. There is a lot of difference in the design of single and multi boggies, so I am pretty impressed that is an option. $\endgroup$
    – OSUZorba
    May 18, 2016 at 3:46

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