Bell P-39 Airacobra: New Project
I recently received a set of the P-39 scanned blueprints for the Bell P-39 Airacobra. An underrated aircraft not popular with the Americans or Brits but was very successful with the Russian air force on the Eastern Front, particularly the 9 GIAP, known as the ‘Regiment of Aces’. There are plenty online resources documenting the amazing history of this aircraft, suffice that I would find it difficult to add anything significantly new here.
The set of drawings; approx 11,000; are actually very good quality scans of which I have spent some time looking through and randomly modeled a few items…like this part for the Landing gear nose wheel travel indicator.
Most aspects of the main structure are also well covered with the ordinates included on the detail drawings and not as a separate sheet. This could be an interesting project and although not entirely a rare aircraft; as we still have a few flying examples and static displays; I do think it will be a worthwhile aircraft to develop. Most of the examples unfortunately are based in the US but there is one on display in Finland, for which a visit is on my to-do-list later this year.
I’ve played about with modelling some bits and reviewed the drawing organisation. I now need to get down to some serious work starting with reverse engineering the ordinate data on the drawings to establish an ordinate record and create the mold lines.
Sample: Ordinate data copied from manufacturer drawings maintaining original format.
This Dataset is then restructured in a separate worksheet to derive the X,Y,Z coordinates for input into CAD.
The ordinates are important for modelling so we can loft the surfaces to check the angle of the frame flanges for correct alignment and also enables us to model parts in the 3d space sufficient that their location in the final assembly is already determined.
This is definitely a long-term project for which I will post updates on progress, though not quite as regular as I have done in the past for previous projects.
Other project Ordinates:
P-51 Mustang available here: Mustang P-51 B/C Ordinates
Ta-152 available here: FW 190 & Ta152: Ordinates
Aviation CAD TechNotes 