Jump to content

sovereignhobbies

Members
  • Content Count

    623
  • Joined

  • Last visited

Community Reputation

843 Excellent

1 Follower

About sovereignhobbies

  • Rank
    Advanced Member
  • Birthday 09/03/1981

Personal Information

Recent Profile Visitors

2,789 profile views
  1. I think I've just about brought this thing to heel and haven't yet had to do anything I didn't want to do. In addition, I haven't yet installed any of the mass in the engine nacelles. There is space ahead of the CofG for almost as much lead shot again in the crew tunnel as is already in there. The tailplanes, elevators, fin and rudder have had a whole heap for plastic shaved out from inside - and they're still very substantial and feel as rigid as they ever did (there's just less risk of punching a hole in a concrete floor if I drop it tail-first now!). I've also managed to get a lot more lead right up front by using tiny balls of lead. I found a small 2.5kg bottle of the stuff in my boxes of r/c stuff that has been neglected since I moved house 5 years ago. This weighing is far from accurate because with all that lead in the nose it no longer sits happily on the fulcrum at the intended CofG. Now it tries to slide off and as it's nudged forwards or back it swings from going nose up to nose down. In otherwords, it's more or less there and some mass at the engines should see it right: It won't lie still now: Tailplanes - much thinner, still thicker than most kit parts I filled the upper forward turret tub thing with lead: No ballast has been placed in the bomb bay yet (only inside the tunnel) There was a lot of space to fill with lead still - it's just that cuboid shaped iron weights were inefficient at using curved spaces - the cockpit floor piece now weighs 164g alone:
  2. Hi Steve, I haven't but it looks very useful - I'll get some ordered, and thank you! Some Alclad aluminium has been sprayed in the nose wheel bay ...which will next receive some subtle oil washes just to pick out the details and add some variation.
  3. I've been an idiot. I tried the nose weights in place and re-weighed the tail, then used the new residual weight on the tail for the moment and took credit for the nose-weights already in there again. I've had to re-do that. I might be able to get a bit more in at Position A2 above using lead shot instead of wheel balance weights. That will require me finding my bottle of the stuff in the big shed outside.
  4. I'm maybe not a million miles away unless I have my sums wrong... Hopefully this is now fairly self-explanatory
  5. This will be an absolute last resort, but for reasons I can't articulate it will feel like it undermines all my efforts on detailing the cockpit.
  6. It would need motorised propellers and a crew for that Dear Col, plus a tripod of a stand liberated from someone's funcy DSLR camera setup
  7. Some more thoughts on weights... Unlike most I have straddled many camps within a wide world of model making and there are things that the well-seasoned modeller of one camp takes for granted as common sense that seldom occur to well-seasoned modellers in other camps. One of the things I've done before is design, build and fly radio controlled aeroplanes. Like real ones, they have to balance or they don't fly. Every pilot/builder of flying models knows that the correct way to balance a model is to lighten the tail, not fill the front end with lead. Doing the latter results in the total weight going through the roof, the power to weight ratio dropping and the wing loading increasing. The somewhat dimmer aeromodeller tried to offset bad building by fitting bigger engines, but that does nothing to help the high wing loading and high stall (and therefore takeoff and landing) speeds. To arm myself with some data (me coming back to my Engineering roots here) I have inspected the rear fuselage and tail parts from the kit. These are very substantial mouldings and must be close to 2mm thick everywhere. Ignoring the wings for now, I taped the fuselage halves and tailplanes & elevators together and balanced the fuselage on the point where the main wheels coincide. The tailplanes have relatively massive locating tongues which overlap inside the fuselage. Even like this with interior parts missing and no wings, the tail is weighing over 90 grams on the scales: So why am I making such a fuss about the thickness of plastic back there? Because Engineering, that's why... Here are the moments about the Centre of Gravity (which needs to be at or ahead of the main wheels for this thing not to sit on its tail striker) The scale of the drawing is irrelevant because the moment arms only need to be in proportion with each other, not true to life - the results are the same regardless of the scale. The moment about the CoG at the tail (which I have labelled T and which is where most of the excess beef in the tail planes, elevators, fin and rudder are - there is more redundant weight ahead and behind) is the the mass on the scales times the distance from the CoG. The mass needed either immediately behind the cockpit (which I really don't want to do) to balance this out with only half the leverage (48mm ahead of the wheels) is as near-as-damn-it double, or 179g which needs to be considered an underestimate because paint, guns, some PE in the aft compartment etc is going to tip this a little further aft. Point B above the front lower turret is worse still needing 210g placed there to offset the tail's moment. The moral of the story is that for every 1 gram of redundant mass I can Dremel out of the back end of this thing, I save the need for an absolute minimum of 2 grams of counter balance up front which means the finished model is 3 grams lighter than it would have been had I left the tail as-is. If I am to have any chance of getting this thing to sit on its nose wheel without spoiling the interior I have to do this, and the main undercarriage will thank me later when I do. With the nose weight already stuck to the cockpit floor inserted into the fuselage, the same experiment on the scales still shows a residual weight of 60 grams on the tail.
  8. Building up the other side reveals that the Eduard details clash with the Eduard details - note that the folded box when correctly positioned on its marked space on the main etching clashes with the nose-gear bay roof structure, and as a result daylight is visible along the joint where it shouldn't be. I will try relocating these, and if that doesn't work one of the boxes will be omitted. I find this a lot with Eduard PE so it's not really a surprise.
  9. One of the nose wheel bay side walls is done (and so is the sanding board that you are all no doubt wondering about)
  10. Done. Right - I want that big sanding board now...
  11. I got distracted and started making bottles to go on those mounts... there is supposed to be a similar set on the other side. The parts are included on the PE set but they aren't mentioned on the instructions. I found some scrap sprue (sorry injection moulding professionals) that was slightly too big to fit inside the PE retaining band clamps and attacked it with Infini Model's excellent sanding stuff - firstly reducing the diameter and correcting out-of-roundness by spinning it in an electric drill chuck using the 220 grit soft stick, then putting a domed end on it once it was a snug fit inside band clamps. It was then finished up with the 800 grit sanding sponge. Whilst these make rapid work of sanding tasks, it's difficult to accidently sand a flat on to something using the sponges which is ideal for this sort of thing. I added the nozzle for the tubing from brass tube after drilling the end of it once it was to final shape. Now to simply do exactly the same again - not my strong suit!
  12. I may try lightening the tail end a bit. That could be a more natural solution particularly given the long model the tail has and the short moment the nose weight would have. The result would be lighter and less likely to squash the main undercarriage. The Dremel could come in handy! This morning though I have made up another piece of photo etched detailing. I'm going to take a break from this and make up that sanding board I mentioned. Too much PE can result in burn-out.
  13. Squadron has always been the default choice for vacformed canopies and indeed they have the B-29 covered, if I do go that route I've spent some time today procuring GU10 LEDs to replace the halogens in the house (paranoid about those things now and the heat they generate). I also picked up some A4 sheets of 240 grit wet and dry to make a big long sanding board, as I am thinking of building a vacuum formed kit very soon and it might be the 1/48 Avro Shackleton I've had sat unloved for donkey's years. I also spent a few hours on the old Jag X-Type today and have now got my replacement transfer box in (from an older model so it has a viscous coupling centre differential), the torque reaction mounts and propshaft bolted back up and the offside driveshaft back in. I've done a bit of B-29 though. This doesn't look like much but there's quite a few pieces involved and most of them are folded, some at 90deg to make a flange and others doubled over back on themselves to make thicker parts. I've spent a bit of time checking the fit of the surrounding major pieces. The sides have needed a little fettling in general but mostly because of the additional thickness of brass laminated on. I wanted to make sure it was all going to slot together before adding the PE stiffeners on which will make adjustment of the overall fit very difficult without obliterating the brass assembly. The bulkhead at the aft end is not represented in plastic, but is included in the Eduard set. Eduard shows it as being simply glued in place but this seemed a high-risk strategy for closing the fuselage halves later on, so I have backed it with plasticard. The avoid displacing the bulkhead 1mm forward due to the plastic thickness though (which I'm guessing would haunt me later), the plastic only comes down as far as the step in the plastic kit part.  Clearly I have started checking the fit in the fuselage halves too and began sticking car wheel balance weights inside.
  14. Morning folks. It turned out that it was good enough to just go straight for the Mr Surfacer last thing last night. I gave that a rub down this morning. I think I can proceed now.
  15. I agree this is a model and a half, and Col at this point I think I'd rather have had a PE floor I could use than quilted insulation panels I can't. You have to wonder how much trial assembly these sets actually get.
×
×
  • Create New...