Mach 2 DC-8 - Series 60 conversion

[Admiral Puff 2,178]

I've just taken delivery of a Mach 2 DC-8 kit (Eyes wide open - I have experience of Mach 2 kits. This one's actually not too bad!) which I propose to build as a Series 63 in that gorgeous orange/red CP Air scheme. The fuselage stretch I can handle, but I have some questions about the engines.

 

If I understand my research correctly, CP Air's Series 63s were fitted with RR Conways rather than the kit's P&Ws. Am I right? If so, are there any available in 1:72? I have a set of Conways in 1:144, of unknown provenance and fitted with what appears to be pylons for a BOAC 707. If worst comes to worst I could use these as a basis for scratchbuilding a set, but (being lazy, as always) I'd rather scrounge a set from somewhere. Alternatively, can anyone point me towards a decent set of drawings (preferably including pylon details) that could be used as a basis for the job?

 

As a last resort, how easy would it be to convert the kit engines? (The bodies look easy enough, but the bits down the back may be troublesome!)

[skippiebg 105]

2 hours ago, Admiral Puff said:

If I understand my research correctly, CP Air's Series 63s were fitted with RR Conways rather than the kit's P&Ws. Am I right?

Sorry, you are not right. Every single DC-8-62 and DC-8-63 had JT3D engines with the long straight nacelles and so-called "underwing" pylons (ones that leave the leading edge unbroken and do not wrap up (i.e., do not "hook") over it).

 

Quote

 

As a last resort, how easy would it be to convert the kit engines? (The bodies look easy enough, but the bits down the back may be troublesome!)

Which kit do you have?

 

If you buy a DC-8-50-labelled kit (US Navy, Armee de l'Air, Iberia), then you will only have the DC-8-50's engines in their barrel nacelles. These would not be too easy to convert -- not impossible; just not all that easy.

 

If you buy a DC-8-30-labelled kit, though (Pan Am, SAS, KLM), then you will also have (in addition to the said JT3D in barrel nacelles) a very nice set of JT3Cs.

 

Now, as it happens, these JT3Cs are rather too overscale to represent JT3Cs properly... But this is a problem for those who want to make DC-8-30s. As for you, it is a massive boon! Their shape lends them to an easy conversion into the long straight nacelle JT3Ds as fitted to all DC-8-62s and DC-8-63s. You will need to extend them rearwards a bit and discard the noise suppressors. You will also need to convert the pylons and wing leading edge, which should be easy, given you don't find extending the fuselage problematic.

 

---

 

edit: I do have some Structural Repair Manual JT3D drawings for the DC-8-62 and -63, but they are only good for the basic dimensions and not any detail. Send e a private message with your email address if you would like me to mail them over.

 

Edited Tuesday at 08:16 AM by skippiebg

[bzn20 2,279]

Great answer above from skippiebg .

 

The other thing to think about are the wings . The -61 had the wing of the older DC-8  . The 62 and 63 had the new ,different  wing , the undercarriage has a wider track (Edit -63 only ) ,greater distance between right and left units ,maybe not so important as the new wing shape though .

Edited Tuesday at 06:46 PM by bzn20

[skippiebg 105]

Ah, yes, the wing... There are two differences, both minor(ish):

 

- after about 150 aeroplanes, right at the turn of the 1960s, while still making straight-jet DC-8-20/30s and "leaky turbojet" or "bypass" Conway-powered DC-8-40s (okay, it had also made a handful of turbofan DC-8-50s by then), Douglas switched to "the four percent wing" -- one with 4 percent greater chord. It had a slightly sharper leading edge. To appreciate how much four percent changes the appearance of things, take a look at a BUA, Ghana or RAF VC10 or any Super VC10 -- these had a four percent chord extension covering just the inboard two thirds of the wing, making the difference immediately obvious -- look for a notch or break in the leading edge for a before-and-after picture. (There must have been some magic about the figure of four percent in aerodynamic circles, since both Douglas and Vickers went for it! In both cases, it cut drag by quite a lot.);

 

- all DC-8-62s and DC-8-63s had 3ft/91.5cm longer span -- 18in/46-odd centimetres each side, or about 6.3mm in 1/72 scale. This was added to each wingtip. It did not affect anything else; undercarriage track and engine distances from the centreline all stayed the same. (Here I am ignoring a very much earlier and very minor wingtip extension which was retrofitted to all machines built until then -- a few dozen of them, if I remember right.)

 

If one were feeling manic about showing it, I'd imagine the sharper leading edge of the four percent wing could easily be represented by a strip of plastic card/length of Microstrip glued to the leading edge and faired-in with filler. All the better if you are doing a DC-8-63 since this version had "underwing" pylons so no fiddly mods to make the pylons conform to the new leading edge! The wingip extensions would be fashioned from plastic card.

Edited Tuesday at 02:56 PM by skippiebg

[bzn20 2,279]

3 hours ago, skippiebg said:

undercarriage track

Not that this would be replicated  a model  but ...... The track between  wheels on each Bogey on the DC-63 was wider so wheels No1 and no2 ( Forward outboard and forward inboard) were further a part and like wise Wheels No3 and No4 ( outboard rear and inboard Rear ) were further apart ,with slightly bigger tyres due the load bearing pressure on the tarmac .This means the actual track between left and right Bogey  was wider apart measuring the outboard to outboard tyre centrelines are further apart as a result . The U/C legs were in the same position as the earlier DC-8s . I think I gave the impression that the 62's was also which it isn't, I've inserted an edit on that post to that effect.

The VC10 wing is another subject you could write a book about except to say the VC10's is a different kettle of fish to the four 1st generation US 4 engined jets . 

[Admiral Puff 2,178]

Thanks to you both! I now feel much more confident about embarking on this project.

 

As it happens I have the SAS kit, having intended to build those markings before unearthing about 20 shots of a CP Air Series 63 aircraft that I took at Sydney (Kingsford-Smith) Airport on a wet Saturday afternoon in the late '70s. That discovery prompted the research that lead to this post.

 

Skippiebg, pm on the way.

[bzn20 2,279]

Going to look good all that shiny NMF to control . Would you use something like ( 1960s warning ! ) Metal skin or paint  ?

 

[Admiral Puff 2,178]

I'll probably use foil for the NMF, which should be a fun exercise! If I can't get up the courage to do that, I'll probably use Alclad in its various permutations to get a bit of variety in the finish.

[bzn20 2,279]

Foil , Remember a 1960s Airfix mag had a WIP and  using Foil a brand new thing  ,called it Metalskin and the WIP was on a 1/72nd P-47 .  Bit scary !

 

[Space Ranger 3,279]

You can find the official Douglas display model drawing for the Series 61 through 63 here: https://postimg.cc/N56QD1Gr

 

Unfortunately, Sheet 1 is missing, but this does show plan and profile views.

[skippiebg 105]

11 hours ago, Admiral Puff said:

 pm on the way.

Reply sent

[Admiral Puff 2,178]

21 hours ago, Space Ranger said:

You can find the official Douglas display model drawing for the Series 61 through 63 here: https://postimg.cc/N56QD1Gr

 

Unfortunately, Sheet 1 is missing, but this does show plan and profile views.

Thanks, Michael. What a pity Sheet 1 isn't there - it looks as though that had all the section drawings on it ...

15 hours ago, skippiebg said:

Reply sent

Email inbound.

[Space Ranger 3,279]

1 minute ago, Admiral Puff said:

Thanks, Michael. What a pity Sheet 1 isn't there - it looks as though that had all the section drawings on it ...

I have a large Douglas model drawing of the Series 30 variants which does include the sections. However, it is in very poor condition and would probably not survive a pass through a large format scanner/copier. If I can get it restored to a reasonable and sound condition, I’ll post a scan of it.

[Admiral Puff 2,178]

1 hour ago, Space Ranger said:

I have a large Douglas model drawing of the Series 30 variants which does include the sections. However, it is in very poor condition and would probably not survive a pass through a large format scanner/copier. If I can get it restored to a reasonable and sound condition, I’ll post a scan of it.

That would be much appreciated, Michael!