Perhaps the reason it is so far behind the likes of the Smithsoniam is funding. There are plenty of people on this forum who are quick to knock establishments like the RAF Museum yet I bet seldom offer their time up to volunteer to help.

I have over 30 years experience in Drawing/design office management and an integral part of that job was document/drawing control – so when I realised that the RAF Museum had some issues with their drawing records I naturally offered my services – which incidentally fell on deaf ears!

Unfortunately I could not volunteer my services as I dont live local to the museum.

Now why in this day and age aren’t they storing these films digitally? When a drawing is requested charge a nominal fee and tell the requester that part of this fee is towards the digitisation of the original document which will then go into a digital archive. Once the microfiche is properly scanned it can be stored in a digital format and printed from a regular A3 laser printer. No more messing with, an potentially damaging, microfiche which can then be put into deep secure storage as archive media.

I agree entirely and for many museums this is exactly what they want to do. However an exercise like this has to be done properly – note I didn’t say professionally – because not all professionals in the business of scanning to digital know exactly what needs to be done with film archive material and/or are driven by commercial need.

After all what we don’t want is scanned film archives done in B/W colour space and saved as .BMP files – this may sound unlikely; but it is commonly done because it is quicker to scan B/W than say 16-bit Grayscale or 24-bit RGB.

Its where the longeron cranks on the rear fuselage structure. The Low’n’Slow drawing shows the centre of crank in line with the centre of the cross members – however this cant be the case if the cross members are chamfered across the depth of the material section.

There is also an issue with the dimensions of the rear fuselage that dont match with the part drawings ref DH Drawings H27745 & H27746 – but perhaps we should leave that for another time.

As Blue Max points out, although the cross tube you mention may carry a DH part number, the rear fuselage frame is officially regarded as a single, factory-jigged, welded structure. Repairs are possible on this, but if the airframe is being restored to fly, they must be carried out in accordance with approved DHSL repair procedures and, in the UK, be carried out by a CAA-approved welder.

Thank you again for your help.

I should note that I am not interested in building one – I have a background in structural engineering and this is a research project on the structural design and configurations of various aircraft primarily from the 1920s through the war years.

Integral to this is the development of 3d cad models (incidentally 26 years experience in that field) from which I can do geometry analysis, structural analysis and working simulations. To do this correctly I need to be absolutely sure that everything is dimensionally correct.

As I have already discovered a number of dimensional anomalies I cant make any assumptions without some verifiable data. Unfortunately the drawings I have are not that great with some key data illegible or missing.

With regards to the cross member in question – the very shape of the part suggests that it has to be offset from the centre line of the cranked longeron, whereas on some GA drawings; done by others; it is centred – so we have a conflict which requires resolution.

I have also noticed dimensional discrepancies with the rudder spar and the horizontal stabilizer main spar.

This sort of stuff is definitely not easy and consumes many hours just resolving small details and consequently any help in this respect is gratefully received.

[QUOTE=AgCat;1511852]Buy a copy of Stephen Slater’s new Haynes manual on the Tiger Moth, if you are serious about your Tiger Moth project, as described on other threads.
QUOTE]

Thank you for your suggestion – which incidentally I followed through with a purchase of this manual.

I had a look at the details before purchase and noted that the cover states ‘all marks covered’ – unfortunately as it turns out they are not.

The DH82C for example is not covered at all except for a 2 line sentence in the appendix.

The manual is still useful but not as much as I perceived it to be.

Also check out pages 32-33!;)

Yes I saw the ‘chapter’ – just an overview of the differences. It will still prove to be a useful resource, but not what I expected.

Personally I would liked to have seen a more detailed side by side comparison of the variant differences.

My main issue, as mentioned, is the fact that this is supposed to be an ‘owners manual’ for ‘all marks’. So why was ‘all marks’ written on the cover when it barely covers anything else other than the DH82A?

Fuselage Angular Deviation?

Getting back on topic:

I previously discussed the angular deviation of the top longeron structural member, essentially cranking at what is supposed to be 4 degrees to 9 degrees.

To explain this issue further I have set-out the top longeron (as per attachment) according to the dimensional information on the de Havilland drawing.

As you can see the angles at A,B,C do not conform to expectations nor in fact do they comply with the actual angles stated on individual part drawings which include bulkheads, cross members and the actual cutting drawing for the longeron. ‘A’ should be 5 deg, ‘B’ should be 9 deg and ‘C’ should be 4 deg.

Further the actual permissible deviation along the main part of the longeron is +/- 5mm; however the angles shown, according to the dimensions, exceed this permissible deviation.

Without reference to the actual jig drawings it is difficult to determine what is right and what is wrong.