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      electraglider


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      Post #74359, posted on 01-30-2020 GMT-5 hours    
      Who makes short body DC-8 kit? I would like to build it as a Conway powered model, no one but me will care about what its jet power was. I know about AA's -50 and that Welsh might have one, but at 79 vacs are now a strain. I am looking for an ejection kit still available in 1/144th scale (not the old Revell kit). Why a DC-8-Conway you ask? I flew my first long distance flight via Air Canada (Toronto to Antigua) back in the 60's on it.

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      mark m


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      Post #74361, posted on 01-30-2020 GMT-5 hours    
      The Minicraft DC-8 Super 60/70 kit is actually a very good model. They put grooves inside the fuselage to show you where to cut it to make the original short fuselage. Add Contrail RR Conway Engines and you get a DC-8-40.


      Bagged DC-8 kit: https://www.airline-hobby-estore.com/product-p/m14521b.htm


      Contrails RR Conway Engines: https://www.airline-hobby-estore.com/product-p/cm44-dc8-40e.htm

      Hope that helps,

      Mark

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      skyking918


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      Post #74362, posted on 01-30-2020 GMT-5 hours    
      Eastern Express has announced one for future release:


      Michael McMurtrey
      IPMS-USA #1746
      IPMS-Canada #1426
      Carrollton, Texas

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      Luiz Claudio


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      Post #74363, posted on 01-30-2020 GMT-5 hours    
      yessssssssssssssssssssssssssssss

      Luiz Claudio

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      aptivaboy


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      Post #74364, posted on 01-30-2020 GMT-5 hours    
      And, if AHS is sold out then I believe Draw Decal offers bagged Minicraft kits, too. Some come with Draw decals.

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      Jeff Jarvis


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      Post #74365, posted on 01-31-2020 GMT-5 hours    
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      skyking918 :
      Eastern Express has announced one for future release:





      Greetings!

      I just hope I'm still alive by the time it gets here.... The difference between the EE projected kit above as a DC-8-32 and a Conway powered -40 series would be only in the chin scoop on the pods and a slight difference in the ejectors, and that assumes that they make the kit with the ejectors extended as shown above.

      If you reference photos of the engines from in front of the intakes you'll notice that the JT4A engine has a wider chin scoop than the RR Conway and the rear of the cowling is squared off on the JT4A so the ejector will fit inside when retracted, but the rear of the cowling is round and so are the reverser doors in the ejector on the Conway. Look at photos and you'll see it clearly. These are little things most people would never notice, and that is why we have Jennings! HE will notice such things....

      Regards,
      Jeff Jarvis

      God's "Curse" to aviation!

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      electraglider


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      Post #74461, posted on 02-11-2020 GMT-5 hours    
      mark m
      I thank you for the information on short DC-8 modeling. I am hoping your knowledge is deeper as now that I do have the kits you mentioned I still have questions. The DC-8-61 kit has the 3 cut locations, but why? As I have researched there's only 2 body lengths 250 foot basic body and the DC-8-61 with a 240 inch fwd ext and a 200 inch rear extension, so why do they give 3 cut line options with no marked data embossed or raised on the part interiors? One, I know is the basic center body cut closeness to the wing joints, but the next is just forward of that. The other is diffidently the frt fuse cut line . Why give a 3rd just forward of the center body cut?
      Concerning the Conway shapes,. I've seen parked -40's DC-8's with their noise suppression rings extended rearwards of the basic engine nacelles Do they stay that way until again airborne then retracted or do they become retracted as soon the engines are restarted? I wish I'd noted that visual anomaly when flying on a -40 back in 1967,

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      Gus


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      Post #74462, posted on 02-11-2020 GMT-5 hours    
      Hi, in fact there are 3 body lengths.
      Standard for -10 thru -50 series
      62 series
      And 61/63 series
      I have drawings that I can scan and send you.
      Cheers
      Gus

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      Ken Miller


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      Post #74464, posted on 02-11-2020 GMT-5 hours    
      As to the cut marks on the Minicraft fuselage someone somewhere must know which marks correspond to which fuselage length. I'd guess the innermost marks are the first cut lines, the next outer are for a -62, and the outermost ones are to make a -50 or earlier. I did a -62 back in the day that turned out well. Definitely measure twice and cut once.

      Ken

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      scotty100368


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      Post #74472, posted on 02-11-2020 GMT-5 hours    
      Ken,

      This should make it clearer:


      Scott Garard
      YSCB/CBR

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      electraglider


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      Post #74489, posted on 02-12-2020 GMT-5 hours    
      Thanks Gus, Ken & scotty 100368

      I made the right choice, but worried until I saw this. The short front body really looks awfully short verses today's aircraft body lengths. The initial production 737-100 and DC-9-15's look like egg plane charractures compared to their later body lengths.

      I'm still at a loss as to the Contrail's Conway details (no hint nor drawing to where the noise suppression ring is to be mounted except it must at rear. I looked at an old (1960)airliner book with some drawings and Canadian Pacific AL web site. Some have small photos that show the rings in extended rearward with most of exhaust pipes and rear cone in view and others show it retracted on the ground. The kit parts themselves look like they were made by two sources. The after rings won't sit back far enough and if in retracted they won't fit smoothly against main engine nacelles. Accepting that noise rings were kept in the deployed position from landing to the next takeoff while on the ground it still looks as weird as seeing today's planes keeping the spoilers raised from landing to next flight while on the ground.

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      skippiebg


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      Post #74492, posted on 02-13-2020 GMT-5 hours    
      The JT3, JT4, and Conway fitted to DC-8-10, 20/30, and 40 had what were called "translating rings" (more rarely termed "translating cowls") at the rear. These contained the thrust reverser doors and also the noise reducing pipes (PW) or daisy petal corrugations (RR).

      The translating rings were extended at low speeds= On the ground, they were most often left extened, though this depended on individual airline operating procedures. (Pan Am and TCA appear to have stowed them on the ground.) Though it appears strange, they supposedly offered a slight thrust increase when extended.

      They definitely never acted as spoilers and any similarity is superficial! As to spoilers, flaps, and thrust reversers, the 1960s and 70s offered numerous examples of airliners left on the ground with such items left deployed. I remember a green corporate DC-9 at Heathrow's south side (today's Terminal 4) which was seemingly never out of reverse mode. Birds apparently often built nests in the open machinery...

      I agree that the Contrails engines are poor. Once you solve the translating ring location puzzle, you are left with ugly and oversized pylons. Subjectively, F-RSIN made a better set about 15 years ago. The best are by Braz. Braz also designed the JT3s for Minicraft's kit. These never got tooled up.

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      Jeff Jarvis


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      Post #74493, posted on 02-13-2020 GMT-5 hours    
      Greetings!

      Peter, the translating ring assembly is fitted on the DC-8-62 and -63. It extends only for thrust reversing, and the engines are JT3D-3B or -7 only, and the fan air is ducted through a long bifurcated duct to the hot stream exhaust at the tail pipe. If reverse is not selected, the translating ring is always stowed fully forward, but it is not what was fitted on the earlier DC-8 as explained below.

      The earlier DC-8 airplanes (-11, -12, -21, -31, -32, -33, -41, -42 and -43) were fitted with JT3C-6, JT4A-3, -9, -11 or -12, or RR Conway engines and had ejector assemblies fitted. The ejector was extended without necessarily planning on using reverse thrust, and was normally extended/retracted by the use of switches above the Captains head, and in the event of a hydraulic anomaly could be extended by a pneumatic bottle, and also with normal hydraulics by selecting reverse with the throttles, in which case when reverse was deselected on the throttles, the ejectors would retract and stow. Some airlines would retract the ejectors after landing and then reextend them before T/O, but most just left them extended on the ground. To do an engine change, the ejector had to be extended, and it stayed on the pylon in its rail track. Ejectors increased thrust output up to about 150 knots and also reduced the noise by several decibels. Above about 150 knots the drag increase negated any thrust gain, so the ejectors were retracted very soon after T/O. If an ejector was inoperative, it would be deactivated in the retracted position because any extended ejectors would increase cruise drag by a significant amount. All of the DC-8 models used inflight thrust reversing for rapid descents or slowing down. Flight spoilers operated only at slow speeds and only with the landing gear extended and were there only to improve the roll rate. They also extended (as ground spoilers) on the ground to destroy lift and help make braking more effective.

      I hope this info is helpful, and I did not intend to step on anyone's toes! My apologies if I did......

      Regards,
      Jeff Jarvis

      God's "Curse" to aviation!

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      electraglider


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      Post #74495, posted on 02-13-2020 GMT-5 hours    
      I had forgotten the that operational usage methods are dictated by the companies who own them and not to the discretion of the command pilot themselves. That would explain why I have a nice clean Air Bahamas DC-8-40 photo wearing old Air Canada red and white color scheme with them extended and all TCA/Air Canada shots with them closed.
      The spoiler comment was meant as an illustration of what an odd look it would be if seen today verses this translating suppressor ring extended under the wing being left that way during shutdowns. I was going to mention thrust reversers being left extended after shut down, but that seemed too unbelievable til you just said that. I think only as being part of a diorama could you get away having doors and cargo hatches open and gear down. Think of the criticism if displaying a 707 with its inner main wheel doors open?

      I had forgotten what the quality of Contrail kit parts were its been so long that I've seen any except my Sturgeon and I bought Air Waves props for that. The best that can be said about the Conways is that the basic nacelle looks somewhat good, but the pylons profile shapes vary on both the 2 inner or the 2 outer to each other and aft rings need a total remake. I am now wondering if just buy a set of JT4A from Bra.Z after market source and substitute them It would be alot easier and less noticeable? I could steal the P&W pylons from the -63 and remodel the shape. I once gave a class presentation back in the 60's on bypass engine vs turbojet merits. Most didn't care about either then and most are now dead, so who's going give me flak now. I know I have data somewhere from the past, but as you get older it becomes unretrievable & unhealthy for you to do so searching for it now.

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      Post #74496, posted on 02-13-2020 GMT-5 hours    
      Wow, some amazing info on the DC-8. Sounds like the DC-8 was one helluva airplane, and I thought reversers deploying in flight was a death sentence.

      Regards,

      ahmed

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      Jeff Jarvis


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      Post #74497, posted on 02-13-2020 GMT-5 hours    
      Greetings!

      I guess I should add that inflight reversing was only supposed to be used on the two inboard engines, only down to 190 KIAS and only in the clean configuration, i.e., flaps retracted. I had to use it on numerous occasions because of ATC holding me higher than I wanted to be in my descent planning due to traffic below. When pulling the engines into reverse in the air you could do it up to Vmo or Mmo, but that was very hard on the airframe, so I preferred to slow to 250KIAS or less, then let the jet speed up while in reverse. There was a restriction on trimming to less than 0 degrees ANU because when cancelling reverse with the trim below 0 the airplane could go into a negative G dive and be hard to control and then recover. Does a negative trim crash in Ethiopia and one into the sea come to mind? When pulling up on the reverse levers the reversers will usually not go in at the exact same time and the sideways jerk will leave no doubt in your mind which one went in first! Inflight reversing is quite noisy and causes a lot of shaking, but it does work well. Sharing this inflight reverse feature with the DC-8 are two other jets, the C-5 and the HS-121 Trident. Yes, believe it or not, The Gripper used inflight reversing!

      You're right Ahmed, the DC-8 is a helluva airplane, and probably the most structurally sound airplane I've ever flown. It was exempt from the aging aircraft regulations by the FAA, but no Boeing model ever was.

      Happy Valentines Day to all of you and your significant others!

      Regards,
      Jeff Jarvis

      God's "Curse" to aviation!

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      electraglider


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      Post #74500, posted on 02-14-2020 GMT-5 hours    
      Jeff
      The Conrail parts have a partial half moon depression on the sides of the main engine nacelles at the ring joint. The ring part has what I expected to see a simple cutoff in one plane. It seems to me any translating rings I've ever seen are those that form a flush fit (line to line single plane contact when closed) to the main engine nacelle skin when retracted not not have any lateral projection half moons extensions on their sides. These rings don't just slide rear wards and have clam shells integral with the rings do they? There is a elliptical line on the ring and have a streamlined half tear drop fairing at their bottom of outer engines on the extended ring on the ex Air Canada -40 in use by Air Jamaica in (Airliners.net). A Pan Am DC-8-33 in a rear quarter view taxing with rings still extended , but no clam shell speed reducers deployed or at least any longer. The rings themselves look too thin to being able to do both motions. If they do do both those motions in 1/144th scale the whole things gotta be made out of thin metal.

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      dave6376


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      Post #74501, posted on 02-14-2020 GMT-5 hours    
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      aro757 :
      Wow, some amazing info on the DC-8. Sounds like the DC-8 was one helluva airplane, and I thought reversers deploying in flight was a death sentence.



      I know it's off topic but all variants of the Trident could use reverse thrust in flight.

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      Ken Miller


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      Post #74503, posted on 02-14-2020 GMT-5 hours    
      Yes I'm know I'm straying off track.
      I believe that when reverse thrusters deploy in flight asymmetrically things go REALLY BAD.

      Ken

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      Post #74505, posted on 02-14-2020 GMT-5 hours    
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      Ken Miller :
      I believe that when reverse thrusters deploy in flight asymmetrically things go REALLY BAD.



      There are very few things in this world I'm 100% certain of, but that's one of them.

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      Post #74506, posted on 02-14-2020 GMT-5 hours    
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      dave6376 :
      I know it's off topic but all variants of the Trident could use reverse thrust in flight.



      The Gripper didn't like to fly in the first place! I can't imagine why you'd want to use t/r in flight!