How Heavy are Lancaster Bombdoor's

Peter, you always have stunning photos. Thank you. Mike

Thanks guys, you’ve been most helpful as always.

Bomb door detail you can see one of the many ribs and the central spar. I would go with them being around 100 lb’s or so each…

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“Possibly not taken any notice of as not being relevant to the question asked”

So if Lancaster bomb doors were 33 feet long x 2 ft wide = 10m x 0.6m = 6 m2

The He177 bomb door was 2.3m x 0.8m = 1.84m but weighed 30kg

The Lancaster would be 3.2 times the area and hence (approx 3.2 x weight of 30 kg)

Therefore the Lancaster doors (of an equivalent construction) would be 98kg each.

I wait to see what is eventually confirmed.

I would look at the ailerons for the Lanc, I would expect construction to be similar; I don’t know what size they are, but they are normally very light, (although often weighted along the leading edge with quite a lot of lead) I would guess at something like 100kg ea.

AVRO Lancaster Hayes owner’s workshop manual.
Bomb doors. The two bomb doors run from just aft of the joint at Former E to former 22. They are made up of a central spar with nose and main ribs and are covered with a thin alloy skin (24 gauge). Each door has a hydraulic jack attachment at each end.

Most sources state Bomb bay is 33ft long, I am guessing they are 2ft wide, and 24 gauge thick. (0.0201inchs)
396 x 24 x 0.0201ins = 191.03 cu ins x 4 sides = 764.12 cu ins x 0.09 lbs = 68.77 lbs 31.19 kgs
So add in the main spar, ribs and rivets I would say the total weight of doors is somewhere below my original estimate of 856 lbs 388kgs.

Since none listened first time round – not sure why – but here is the listing and data for the He177 double skinned large door:

A Bomb bay door was sold on ebay Germany last week – 2.3m long , 80 cm high and 30 kg –

http://www.ebay.co.uk/itm/Klappe-Bom…vip=true&rt=nc

An extrapolation based upon surface area should give a reasonable first approximation!

Possibly not taken any notice of as not being relevant to the question asked. Aeronut actually came up with the sort of information I was looking for. Nice to see the thread generated some interest though, I didn’t think anyone would be interested.

Surely someone’s got the AP which will give the dimensions and weight of each major component.

If I recall the bomb bay door from the He177 that was on offer earlier this year was 30 kg.

Since none listened first time round – not sure why – but here is the listing and data for the He177 double skinned large door:

A Bomb bay door was sold on ebay Germany last week – 2.3m long , 80 cm high and 30 kg –

http://www.ebay.co.uk/itm/Klappe-Bom…vip=true&rt=nc

An extrapolation based upon surface area should give a reasonable first approximation!

I will possibly shot down here, but a guess of the weight of the bomb bay doors would be 856 lbs. 388kgs this does not include hydraulics operating the doors.

To get an accurate weight of the doors, we would need to know the size, amount of the component’s and what material they are made from.
Or take a door off and weigh it.:)

However let’s say each door is 33ft x 2ft x 2ins and made from solid alloy.
396 x 24 x 2 = 19008 Cubic inches alloy weighs approx. 0.09 lbs. per cubic inch.
19008 x 0.09 = 1710.72 lbs. 2240 lbs. = 1 ton.
We know the door is not solid, so how much space is taken up by air?
Let’s say three quarters air and one quarter metal.
1711 lbs. / 4 = 428lbs x 2 = 856 lbs. 388kgs.

Ah that would make sense. The last thing you want is to open them and have them deformed by the slipstream so that they won’t close again. I imagine they would be quite weighty items then.

[QUOTE=mike currill;2157901]

Mike – there certainly were ribs and stringers.

QUOTE] So am I correct in thinking there was an inner and outer skin then? Excuse my ignorance but I only ask because I don’t know.

Yes, there were inner and outer skins, along with internal ribs. They are quite sturdy affairs to deal with being opened and closed at speed.

[QUOTE=Eddie;2157665]Mike – there certainly were ribs and stringers.

QUOTE] So am I correct in thinking there was an inner and outer skin then? Excuse my ignorance but I only ask because I don’t know.

If I recall the bomb bay door from the He177 that was on offer earlier this year was 30 kg.

Mike – there certainly were ribs and stringers.

I think the reason the bomb bay was cut away to clear the tail was to move the centre of gravity of the bomb closer to the centre of gravity of the aircraft. After all – all of the weight of the bomb is at the front – the tail is just light sheet construction.

Not as far as I know. I think it was pretty standardised throughout its service, I think 69’9″. Looking at pictures of the doors there appears to have been no ribs or stringers which surprises me as I would have thought that would have left them so flexible that every time they were opened in flight the airflow would have wrecked them.

Maybe the aircraft was lengthened to accommodate extra fuel required to enable the aircraft to get to the targets ok?

Mathies, thanks for that comment. Yes I was aware that they wouldn’t have closed with a Grand Slam in situ nor with a Tallboy which is why the ones used for the Tallboy had bulged doors. I see no reason to have lengthen the bomb bay as it was already 35 feet long and the Grand Slam was, to the best of my knowledge about 27. Having seen the dummy of one at Conningsby they would have fitted comfortably without modification other than removing the doors.
Thank you to whoever decided to make this a separate thread, I did consider starting a separate thread with this question but decided to tag it in to the other one as the people comme3nting on there seemed to be very well informed on the subject.

Mike, it wasn’t just a question of weight saving – the bomb doors wouldn’t have closed around the great girth of Grand Slam and the bomb bay was extended backwards on the ‘specials’ as well. HTH.
Matthies