SE5a CONSTRUCTION BEGINNING TO . . .

[Guest]

Hi Grahame,

Nice Pics and she looks nicely weathered too, love the rusted exhaust on the engine. The Pilot looks happy and to be honest I would be too sitting in that plane.

Like Terry above says, Looking forwards to the flying shots once the engine is sorted.

Regards.......Mark.

[Guest]

Obviously I'm delighted to see the silver soldering greyhead is doing looks like mine! Most encouraging. Ho ho.

Am I right in remembering that you've used silicone tube as the seal between the Laser exhaust and your copper housing, as well as for the extension running to the bottom of the aeroplane? Isn't there a chance this silicone is going to go the same way as you Elf and melt/deteriorate in time?

[Greyhead]

Giles

Glad you feel a bit better about your silver soldering! I have to admit that the example shown above isn’t one of my best, it had previously been soft soldered which does cause some problems but it still worked and looked OK once it was cleaned up.

I have indeed also used silicone tube as a seal, after all Laser use rubber O-rings to seal the exhaust stub to cylinder head joint. Only time will tell if it’s up to the job, it's only early days as yet, but so far so good!

I do have my doubts about using silicone tube after my experience with the Elf but it that case the tube was between the engine and the silencer. Gasses cool as they expand so after the silencer, which is really just an expansion box with a restricted outlet, the exhaust gasses will be cooler and there will also be less pressure. That’s my theory anyway; but the whole system will get a thorough testing attached to the AcroWot before I decide whether or not to fit it to the SE5a.

Grahame

[Greyhead]

Positioning the RC switch is often not the simplest of tasks on a scale model because it needs to be easily accessible but at the same time we don’t want it to be visible; there are really only 2 alternatives, either hide it or disguise it.


The most practical way to hide the switch but still be able to easily operate it is to use a scale hatch and the SE5a does have one but it is behind the cockpit so not ideal, disguising the switch seems to be the way to go but how to do it?


Luckily earlier in the thread, when talking about the interrupt gear for the Vickers, Steve posted this photo. It shows the interrupt pump driven by the prop shaft, of course this isn’t included on any of today’s restored aircraft because the Vickers is inoperative. But it does explain why the front has such a large cut out below the prop shaft!





The switches, I’m using a twin power pack, 2 batteries with an electronic switch over for added security, are operated by pulling / pushing the pump gear wheel, from a defunct servo, which is connected via a “snake”.








Not only does it make the perfect “invisible” switch, it adds a bit more interest to the front end,

[Guest]

Brilliant idea Grahame, I keep going over all your pics almost daily coz me loves em.

I shall be building her sooner than I thought, :music_too I was going over my copies of Flying Scale Models July 2007 as it has a feature and free plan of the old war bird.

While reading the article for the ? time, it dawned on me that there was a web page link to buy the laser cut parts, thought this would be easier than cutting them myself as it has been about 30 years since I've done any form of modeling never mind balsa n tissue, should arrive very soon.

Also bought a Revell 1/48 just to check detailed bits. So to start the ball rolling I've just got hold of a KeilKraft Hurricane (ebay) scanned the wood then printed so as I don't use the kit, it'll give me practice with my cutting n getting parts right for my bigger projects. That Sea Otter will get built:yeahbaby:

Enough rant shall close n wish you all the best.

[Greyhead]

Because the basics were worked out well in advance the radio gear has all fitted in with no unexpected problems. The throttle servo, bomb release servo and onboard / remote glow driver are located in the engine compartment, their leads have to pass through the firewall so the resultant hole needs to be sealed to prevent the ingress of fuel / oil into the main fuselage.


A standard grommet won’t work very well because the leads have their plugs permanently fitted, so I made a 2 part seal from a rubber wine bottle “cork”; another of those useful Christmas necessities!





An appropriately sized hole is drilled through the firewall, one half of the seal fitted in place, the leads / plugs threaded through, then the second half fitted, the rubber compresses around the leads forming a good seal.





The onboard / remote glow is located in the engine compartment in order to keep the glow plug power leads as short as possible, the control unit and battery are wrapped in foam and held in place by a cable tie. I’ve complicated the wiring somewhat by including a stereo, switched socket, which enables me to use a remote connection for starting and also, using a different jack plug, to charge the battery.





Previously I've used a homemade onboard glow driver, which simply switched on the glow at a preset throttle setting. But this one is an “intelligent” glow driver; it continuously monitors the glow temperature (actually the resistance of the element) and connects the battery only when required, whatever the throttle setting happens to be. In theory it should be a lot better, but I’ll let you know how it actually works in practice at a later date!

[Greyhead]

I ran the Laser up yesterday to test the plumbing and adjust the onboard glow. As I mentioned earlier I now have an “intelligent” glow driver, that is, it only switches on if the plug goes cold and needs energising not at a set throttle opening. The driver has an LED, which shows when current is being supplied to the glow plug; this is very useful as you can see exactly what is happening.

Having adjusted the driver following the instructions, one thing became quite obvious; with a Laser you really don’t need an onboard glow driver. I’ll still use it if only as extra security just in case a plug goes faulty when I’m sure it would help.

[Greyhead]

I’ve altered the exhaust slightly by incorporating a 10mm copper 90º bend, I found that as the silicone pipe heated up with the engine running, it tended to collapse slightly at the apex of the bend so restricting the gas flow. I have to admit that I didn’t notice any change in the engines performance but decided that it’s better to be safe than sorry.


Connecting the remote glow lead to the plug can be a problem with Lasers, along with most other four strokes, because the plug is recessed quite a way into the head; there are many methods used to make this connection, this time I’ve used the threaded section from a 3mm “quick link”. A very short bolt holds the solder tag and the rest of the 3mm tapped section pushes tightly over the plug post, being made of “springy” metal the threaded section can be adjusted slightly if necessary to ensure a tight fit by squeezing with a pair of pliers.





The power lead is sheathed in silicone fuel tubing for heat proofing.

[Greyhead]

I was chatting in the model shop recently and as is often the case when I’m involved the subject turned to biplanes. The consensus was that they’re more trouble than they’re worth, just too fiddly to set up and awkward to takeoff and land in anything but ideal conditions. I pointed out that my Elf, with its folding wings, is easier to rig than most sports models; but I had to admit that it is the exception rather than the rule! I also had to admit that the flying characteristics of biplanes can be “challenging” but in my opinion the inconvenience of rigging is far outweighed by the appearance of the assembled model and that it doesn’t have to be all that time consuming with a bit of forethought.


My decision to use the scale closed loop control system for the ailerons on the SE5a has made the assembly somewhat more difficult and as I explained the procedure it did sound horrendous, which in reality it isn’t. It’s one of those things that sound complicated in words but when you see what is involved it isn’t, so I’ll take some photos as I assemble the model, which won’t be today as my workroom is too small and it’s raining quite heavily; don’t want to get all those rigging wires rusty!


I’ll start with a photo of the “tools” that I’ve made to make the rigging easier and a brief explanation; it will be much clearer what they do when I post the assembly photos.





From left to right:


One of a set of 4, which keep the cables tight during storage and whilst connecting the first quicklink.


The third version of a tool to hold the quicklinks open


A spring-loaded quicklink


Tensioning tool for the rear flying wires.


I'll assemble the model and take photos ASAP, but just checked our 5 day forecast and it's not looking promising for next week!

[Guest]

OK. Now you've got our curiosity up and tell us we have to wait for it to stop raining in the springtime? ARRRRRRG!!

Steve

[Greyhead]

This is England we're talking about! No such thing as predicable seasons.

[Guest]

Seasons??? Do we still have them?

[Guest]

nice and sunny at the moment.....get those photos!!! lol

Richard

[Greyhead]

You don't live in the North East!!!!!

20 minutes later and the sun’s out!!

But we’re still surrounded by ominous black clouds; I don’t think I’ll risk it

[Guest]

North Scotland, seasons are defined by the warmth of the rain!!