Clive Hall
-
Posts
137 -
Joined
-
Last visited
Never
Content Type
Profiles
Forums
Blogs
Gallery
Calendar
Downloads
Everything posted by Clive Hall
-
-
-
The rear fuselage was redrawn to be skinned with 1/16 balsa sheet, but then decided to be striingered, more in keeping with Peter’s design. This led to a problem, because the formers were cut to fit the sheet and the rear top was already built. It meant that the formers had to be notched for half the depth of the 1/8 square spruce stringers. Fortunately this was easy to fix on the CAD drawing. The formers were then notched. Card templates made from the drawing were held against each former and used to guide a 1/8 inch wide cutter made from two pieces of old hacksaw blade glued together with a thin spacer and with a depth limit on one side. After that the rest was easy. A better solution would have been to have got the drawing right in the first place and to have had the formers laser cut.
-
-
-
-
-
There is a technique for making a clean fine join where the front of the top hatch meets the top of the front of the fuselage. This assumes that the front top bit of the fuselage already has its skin fitted. The first step is to make sure that when the hatch top skin is attached it is slightly too long, so that it overhangs the front of the hatch. It can then be sanded back to a precise match to the face of the front former leaving a sharp outer edge. Next coat the face of the front former with two coats of non-shrinking dope to seal the wood, then cover it with brown parcel tape. It helps here if the fit to the fuselage top leaves a little gap, to allow for the next step. Lightly smear the parcel tape with Vaseline, then mix some P38 filler paste. Make a bead with this round the top edge of the mating surface on the fuselage front then gently but firmly press the top hatch into place. Excess filler should squeeze out from the gap; allow this to happen and leave it to set. Then lightly sand off the excess filler until the top surfaces of the hatch and the fuselage match. Now remove the hatch, peel off the parcel tape, and the front of the hatch should be a perfect fit. The amount of filler left after sanding is small, so its weight is negligible. (There is still a bit of tidying to be done along the bottom edges of the hatch.) The same technique will be used to make a similar fit for the rear of the hatch.
-
-
-
The balsa moulding operation produced well curved sheet, so now it can be attached to the top of the hatch. The balsa used was medium hard, and it was surprising how determined it was to stay in its newly formed curved shape. There was a tighter curve than was needed over the central part of the hatch top, but a small amount of water brushed on the inside of the sheet made this relax to enable easy fitting of the skin. On the outer edges of the hatch the opposite happened, so I brushed a little ammonia on the outside of the sheet here to help the extra bend required.
-
-
The holiday weekend is not good for building time — too many family interruptions. Meanwhile I have to make decisions about the upper fuselage skins. One question is whether to plank the top hatch or to use curved sheet. Peter has kindly avoided double curvatures, so I have chosen pre-formed balsa sheet. First I cut two oversized pieces of 1/8 sheet, one for each side, and then found two A4 sized plastic envelopes that sometimes turn up in the post. These I cut and opened into A3 sized sheets. Then each piece of balsa was laid on its sheet and painted with 10% ammonia solution on both sides. Then the pieces were tightly wrapped in the sheets and left overnight. Next day the previously stiff balsa was soft and pliable and still ponging of ammonia. The plastic sheet idea avoids all need for baths of liquid to soak the sheet balsa. I found an old small towel and wrapped the balsa round a convenient plastic tube, finishing it with many rubber bands to hold everything tight. It now rests on a radiator to dry and should produce two curved sheets, close to being a good fit. The second decision concerns the rear upper decking; whether to use sheet again or stringers. The appeal of sheet is that it should be quick and easy and will allow the same finish to be used over the entire fuselage. I plan to use glass/epoxy. Stringers would require fabric, same as the wings, for which I will use Koverall. (The jury is still out.)
-
-
Peter, if you still have that stabiliser I would be happy to flash it for you. The improvement would open up new features such as proportional control of the gain from the transmitter, and an added 'hold' mode. PM me if the idea appeals.
-
I use FrSky radio exclusively now, having tried it for some time and found its performance excellent. Then I went the whole hog and converted to a Taranis transmitter, which has made all my older gear redundant with its amazing flexibility. Once accustomed to it the programming is not difficult. I have also taken to the Orange stabiliser. When it is flashed with upgraded firmware it opens up many of our otherwise frustrating windy days as safe flyable ones. It has made it practical for my WOT4e to fly in up to 20 mph winds, gusting to 30 mph, without being the least bit scary.
-
-
Ash, I could use a 4 oz tank and the running time would be enough, but Bob C has it right. I plan to use the 8 oz tank simply because it is longer and gives me a reasonable chance that the longer tygon clunk tube will be able to follow most of the fuel round the tank. Keeping fuel in the tank helps to keep the clunk soft, but even with that a short 4 oz tank would be pushing it a bit. Now tonight’s post:— The control runs are steel Bowden cable in black nylon outer. This comes off a roll curved and needs to be made straight. I do this by passing a length of 16G piano wire through it and then heating with a hot air gun. When cooled down the wire comes out leaving the tube straight. I fit it in the fuselage with the wire again inserted, tack the outers to each of the formers with a hot glue gun, and then remove the wire. It makes sure that the cable has a smooth run. The twin aerials for the receiver are routed similarly. They sit in precise positions inside the same nylon tube material, pre-shaped to fit. I sketch the required curve then outline it with pairs of pins, trap a piece of tube between the pins, and apply hot air. When it cools the tube retains the shape.
-
-
-
-
If you can get hold of a copy of “Aerobatics” by Neil Williams he has some interesting things to say, on page 92, about flick rolls and how to use ailerons in some situations to help manage them.
-
The card mock-up also confirmed an easy fit for the ignition module and high tension cable, with room for a large LiFe battery, and that the chosen engine mounting angle will allow the silencer to clear the fuselage. The fuselage build began with ¼ square balsa longerons attached to the top and bottom of each side, then the first four formers and the separating plates were attached to one side. These are self-jigging, which makes sure that they are at the correct angles. Then the second side was attached to the assembly and it went into the building jig for the fitting of the rest of the formers. This stage is done with the fuselage upper longerons resting on the jig base. As the engine firewall is made in one piece the front end has to overhang the jig base. The rest of the formers have the tops added later. The top hatch is built with the rest of the top of the fuselage, with temporary adhesive tape in any positions where the hatch might stick to the fuselage. A thin wipe of Vaseline on the tape ensures that nothing sticks where it should not. It is fixed with two small dowels at the front, and at the rear with magnets. Edited By Clive Hall on 21/03/2016 21:05:59
-
-
