Tiger Cub Story part 22

Humps, pipes and rods

Rough hump - glued n clamped

The SE5 style hump for the back has now been rough shaped and glued together out of 4 pieces of blue foam and ply profiles made for each end.

A friend has promised to try to locate a suitable hot wire cutter for the final shaping, a new skill to learn but it does promise to be easier than hours of careful sanding, so I hope for the best. When the glue is dry I’ll weigh it , it does feel very, very light so here’s hoping the scales agree with the feel

I also wanted to trial fit the Romain vertical stabiliser, as this is already covered by the previous owner I wanted a look inside so I dug out my little cheap borescope and to my delight it gave me an excellent view of the state of the inside.

As it happened it was in good shape matching the other work done by the same chap, all the same it was nice to have looked. I’m in hope that the hump in conjunction with it will look terrific as well, hopefully, helping also to tame the swing a bit.

Other little jobs sorted are a ply inspection panel to give access to the front fin securing bolt and to enable me to fit the rudder cables up though the upper pulleys. Eventually this panel will have a balsa wood fairing fitted to get a clean joint between the rear of the hump and the front of the fin, it will also make it easier to lift out, if needed and avoid trying to pry the panel out and maybe damaging the surrounding foam. With the glue made up I have also repaired the split to the centre section, with that done I can strip off the old covering and that will probably be my trial piece to learn to use Oratex covering, easy I’m told, but we’ll see. Heck, I’ve even pumped up the tyres and sorted out the springs for the rudder pedals, things are starting to move again.

-/-

While I considered the best way to tackle the foam, I placed the cockpit floor made from thin ply roughly in place which enabled me to have a good think about the cockpit systems and layout. One of the main things was the fuel system; the previous one had no provision for a fuel drain something that I was very uncomfortable about. As it happened I had a drain cock that I’d acquired with as part of a job lot, but it was designed to fit straight into the tank bottom something that was not possible in this case. I’d have to fit it on the end of a tube, something that worked well on the trusty AX3, all I needed were the right connections and then when the floor was fully fitted I’d only have to fit it though that and I’d be able to check the fuel. This seemed particularly important as the tank had no sump, a flat bottom with port and starboard draw off points, perfect for delivering debris and water straight to my fuel filter, I’d really rather intercept it before that. Checking what was available for connections to the drain valve defeated me so I consulted the guru and rang LAS, oh yes said the chap on the phone what you need is one of these and one of these, all straight off the top of his head. I was impressed.

So my fuel system, as roughly sketched out on a scrap of paper was pipes from the draw off points coming together in a tee piece another short length of pipe to another tee piece the starboard one leading to the cockpit side (when fitted) and the fuel tap followed by a primer bulb fitted with a bypass to the filter that would be far enough forward to be readily visible as I wasn’t expecting an excess of space in the cockpit. The port line from the second tee piece would go to the tank drain, even so I reckon that I’ll need a fair sized fuel sampler to get a good idea of the tank state. So I put some of this in place as far as the tap fitting anti chafing protection where it was needed. I was using the blue urethane tubing that has given such good service in other aircraft so it would need plenty of support as the only fault that I’ve ever found with the stuff is that being fairly soft it can kink and crush unless thought is given to its use.

Then two good things happened together, the first was packages from LAS and good old Skydrive with the bits that would enable me to build my fuel system, make my rudder cables (after study of the EAA excellent on line video) and put right my mistake with the incorrect washers on the aileron control rods. The next good thing was a phone from out of the blue with an offer from the North Weald Model Fliers club to lend me their equipment and expertise to cut my blue foam, what a result and a very generous offer.

-/-

Back in the workshop I was able to put right my error with the control rods. Have you ever noticed though the habit of split pins how in a slightly awkward place they sneak back and turn just when you think it’s almost sorted? Well three of them went wonderfully, but the one where I was in a bit of a cramped space did its best to make up for that.

The static port in the Romain Cub is mounted on the fuselage starboard side, that will make life a bit easier as I’ll only have to get a single tube out to the starboard interplane strut although it will involve cutting out a short length of foam, known as a “keyhole” slot in the build manual. This is tucked away behind the fuel tank and so needs to be considered at this time as well. Things are slowly starting to come to shape, although I’m sure there are few things yet that will that’ll make me scratch my head it is satisfying… heck I’m looking forward to flying this bird.

-/-

Fitting the cockpit floor was to be the next job to allow me to complete the fuel system as far as the tap and get the pipework clear of the seat, it turned out to be a fiddly job getting everything aligned and I was a lot more flexible after having finished crawling around underneath.

Then the final component to the fuel system landed on the doormat a primer bulb complete with bypass loop made by Mark at Galaxy Microlights. It’s the same type as we fitted to the AX3 a while back and have been very pleased with it.

I already have a high capacity fuel filter from Aircraft Spruce so at last I’m in a position to fit the system as far as the front bulkhead. Fortunately for me Jim Romain, no doubt horrified at the thought of blue foam below the fuel tank even with a tray fitted, had made that section of the lower fuselage of alloy. So I was able to make up a couple of alloy spacers with a soft washer made from layers for tape so that I could tighten my drain fittings through the fuselage bottom. That done it was an easy job to fit the primer assembly and filter all ready for the fire resistant fuel hose that will be used the other side of the bulkhead.

(Written – February 2015)

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