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Jan 29, 2009, 07:08 PM
KE your cub.
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The sound of Silence..

RIght, now I did promise that I'd give you all a heads up on my muffler bastardisation. Well, here it is.

First of I had to find a mousse can of the right dimensions, (approx 40mm) so with my vernier calipers in hand I set off to the local supermarket. Let me tell you, measuring various mousse and deoderant cans with a vernier gets you some strange looks, but for a meagre sum of $3.10AUS, I came away with a can that looked perfect.

On getting it home I emptied the contents (BORING) and drilled ah hole through the top to let any remaining gas out. THen with a dremel cutoff wheel I cut the top off it, which gave me a good 50mm to play with before i'd get to the business end, just in case I made a boo boo.

I then ground down the weld on the end of the muffler till it was a snug fit between the can and the muffer. One that was done I drilled a big hole in the back of the muffler and cleaned up the edges.

Now for the important bit, the looks! The can was sanded to remove the paint (I don't want EVERYONE to know what it was) and trimmed to fit the space I had, (which worked out to be about half of the existing muffler length). I applied a generous amount of high temp sealer to the mating surfaces and smooshed them together. A few small button head screws around the edge hold it together, and a good bake in the oven for 20 minutes to set the sealer.

Once it had cooled I set about Polishing it to a respectable shine. Aftermarket looks for $3.10! Now for the "AH" test. With the extra can on there is VERY noticable difference in muffling if I grab the muffler and try and yell through it, screaming "AAAHHHHHHH" at the top of my lungs, so I think I might have won.

While this isn't a typical "flow through" style muffler, it is based, very loosely on the reactive style mufflers becoming prevalent in automotive circles which send a reflected sound wave back up the pipe which effectively cancels out the next sound wave coming down the pipe. Also, in any muffler "there's no replacement for displacement" so the extra volume should do me more favours too.

I'll let you know the results once I get it tested again!
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Jan 29, 2009, 07:17 PM
KE your cub.
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A few little extra bits...

While I was working on the muffler and the engine, I did a few bits of housekeeping, which might be worth a mention.

Firstly, as I said the engine mount standoffs broke, mid flight, so I wasn't about to have that happen again, so after much research I found that most guys are using hardwood standoffs bolted and glued to the firewall, so that's what I did.It's a hard mount and will probably make the fuselage resonate more than I 'd like. I might in the future build a better resilient mount, but for now I'm still flying, which is the main thing right? right?

Also, another thing which had been bugging me was the fact that on long downlines (say a square loop or a stall turn) a jet of fuel could be seen exiting the vent line of the fuel tank, spraying everything with raw fuel! I added an extra chunk of fuel line to make a loop almost to the back of the tank to stop this happening.

Finally, I noticed that my throttle servo was very wobbly, the servo screws were slowly stripping out, so I faced all the servo mounts with some scrap 1/8" ply. I'd done this to all the control surface mounts in the fuselage, but didn't think the throttle would need it, but it seems with the spring close on walbro carbs, it puts a lot of stress on the mounts. More than I thought.

Till next time.
Jan 29, 2009, 07:20 PM
KE your cub.
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Rudolf the red nose CAP 10....

..had a very shiny nose!
Jan 30, 2009, 11:59 AM
Grumpa Tom
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Muffler looks good! Do you happen to have a decibel meter? If not Radio Shack has a nice one and not very expensive. Do you have Rat Shack in Oz?
Jan 31, 2009, 01:42 AM
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We actually have two at the club where I fly.

Unfortunately the wind was a little too strong to test today, but flying was great, she's really kicking it now!

Next time, "nice legs!" hehehe
Feb 09, 2009, 07:25 PM
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Well guys I have been side tracked for a bit.

No news on the landing gear yet but I've made some inroads into soft mounting the engine effectively.

Working in the marine industry gives me a good source of most of my aluminium needs for free, which helps when I have a crackpot idea.

In this instance I'd figured out what the problem was with my initial mounting setup. There was too much flex in the standoffs, leading (inevitably) to a failure of the threaded rod.

Thinking about it, I needed a way to mount the engine securely to something, and then in turn mount the entire assembly to the firewall using soft nuts. My thinking is that the engine should see no assymetric forces as it's a good way to bust mounting ears. A few mornings scoping around the shipyards came up with a chunk of scrap 80 x 40 x 3 Rectangular hollow section.

I then set about drilling the mount holes and relieving the area around the carb to allow the carb to sit inside the hollow section (perhaps later I might wrap the whole thing in filter foam to deaden the noise a little more).

This still left some 30mm to be made up. I found the old standoffs and measured them, they're 35mm. so with much patience and work in the drill press (I don't have a lathe) I turned the standoffs down to 30mm height.

The box section was mounted to the firewall, and then the engine in turn was mounted to the box. Initial tests tell me that I've got it working a lot better than the hard standoffs as aircraft noise has reduced considerably.

Once I can get a sound meter out there again, I'll let you know the findings.

so what's been slowing me down? Making more models! I found an old Enya .09 in my stuff, and had a giggle at the prospect of flying 1/2a control line stunt...

.... so a few sheets of 1/4" balsa later. We're nearly done!
Feb 09, 2009, 07:29 PM
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In my spare moments before work, I started to knock up a cockpit tub mould to allow me to vaccuum form a light tub.

The results aren't wonderful, but it's effective enough to hold some seats and a pilot when I find a suitable female 1/4 scale figure.

At this stage I'm thinking a Bratz doll is about as good as I'll find.

We'll see.
Feb 11, 2009, 05:01 AM
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I got scared, and I missed it

Well, I'd promised you tales of scratch built shock absorbing landing gear, making touchdowns and the ubiquitous nose overs a thing of the past.

I was going to give you everything, from start to finish, but alas, it wasn't to be.

I choked, as much as it pains me to say, I BOUGHT a pair.

As it goes against the grain of me as a modeller in every respect, I finally conceeded that the time it would take me to get the job done, with questionable results, just didn't meet my expectations.

I purchased a pair of Haiyo Ye shock struts. They're not great, and they're as lardy as John Candy, but like mr Candy, They'll save the day. Hopefully. It was a simple enough task, just chop the gear at the right spot and fit the new shock towers. After goofing around on the floor going "boing boing boing boing" I realised the shock action isn't as smooth as I'd like (once again, can you hear the cries of OCD!!) so I took them apart. the bearing/piston that pushes the spring and acts as the bearing into the receptacle is machined aluminium. Heavy but effective. However the machining marks could still be seen in the sides! For something going up and down, these round and round marks are just tooo much! after a bit of linishing and milling (read me with sandpaper and steel wool) I got a much better surface finish, and now with a bit of grease in the assembly they're just right for the job.

I hope.

Incidentally, while we're on the subject of landing gear, a few things need mentioning.

1. bend the gear forward, as much as it's "NOT SCALE" the plane needs it. after a month of saturday mornings cutting divets in our airfield, I'm not happy, and if I'm not happy, you're not going to be happy either. Unless you're on pavement (you lucky, lucky bastards!) bend it forward.

2. Bend it in. If you look though some of my older photos you can see the gear splays out, I had been telling all and sundry that "thats how real cap 10's are!!" but on closer inspection today, I've been telling porky pies. So while you've got that chunk of miscreant wire wedged in the vice, bend it in too.

I'll get back to you over the weekend with news of whether my dodgy shock towers work, and a few "other" assorted goodies.

Feb 13, 2009, 11:34 PM
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Well, the control liner is finished.

A bit heavy, and probably won't fly but they do look cool on the wall

Today is windy and storms are passsing through so no flying today, tomorrow will be the day!
Feb 14, 2009, 11:02 AM
Grumpa Tom
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Very nice paint scheme on the ukie!
Feb 15, 2009, 10:26 PM
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Well, it was an eventful weekend, but not much flying was done.

The Ukie didn't make a quarter of a lap, as I partially trained my GF to throw the thing, but not enough training was done as she threw it into the circle, not around it. A bit of zap here and there and she's right as rain though.

Onto the shockies.

We'll they work, how well though couldn't really be determined as I had one flight and then realised my needle settings were walking badly each flight, getting progressively leaner as I went). This smacks of a blocked fuel filter screen in the carb, and while I tried to do a field clean out the screw that holds the diaphragm onto the carb was locked so tight I coudln't do it with my biggest screwdriver.

It's now at home await a service, which is good timing. I also have an MVVS 160 that needs a clean out too, and an os 25fp that requires a service to go into my GF's trainer.

It's an enginey kind of week for curare it seems...
Feb 16, 2009, 05:52 PM
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No crap in the carb, a neatly sawn-through crankcase pressure line though!

Looks like it had been rubbing on a patch of the alumnium box section (out of sight) and perforated itself quite well!

Oh and the carb did have crud in it, but not enough to stop it.

Shame I didnt find THAT on sunday!
Feb 23, 2009, 07:00 PM
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Okay after the weekend a few things have popped up that are probably worth mentioning.

1, the shock aborbing struts work, and work well, BUT they do need to be mounted differently thatn the existing torsion bar landing gear. I messed around with a few ideas and the easiest one happened to be fitting a peice of tinplate to the existing tosion bar area of the landing gear to make the legs fixed to the wing solidly, that stops the back and forth motion of the legs allowing the stuts to operate correctly. THe difference in landing is marked, so the struts will get new fairings and the wheelpants will be modified to mount to the bottom (moving) end of the strut, and the bottoms to be filled in as they're wide open now and look a little silly.

The cool news is that I got bored and attached a set of streamers to each wingtip, one red, one blue, about 2m long and went for a good hack around the sky. They look good, and make knife edge spins look spectacular! They could be a little longer, but they're already making the plane pretty draggy, but it does look pretty cool. All I did was glue a U of music wire into each wingtip and threaded the streamer (ribbon material in this case) through a fishing clip swivel to allow them to be removed for transport etc.

Works well enough for me, and makes rolling circles look pretty darn cool.

Okay guys, that's it for me for a while All of these changes will happen slowly, and there won't be any more flying until april, as I need to prepare for an F3A competition at the end of march.

Still, she's good, and getting better all the time.
Apr 22, 2009, 08:39 PM
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The rumours of my death have been a gross exaduration

Bet you guys all thought I'd fallen off the face of the earth, or just not cared at all!

Well, I'm back, and it's been a trying time.

Firstly, the F3A competition training that postponed my building for a while ended up costing me my plane and I never set foot out on the field to compete. It seems I might have sheared a wing bolt or something like that, as it dropped into a hard and fast roll that I couldn't recover from. To cut a long story short, she corkscrewed into trees, and never lived to tell the tale.

Anyway, on with the CAP!..

Now as you all remember I made a nice tub for the cockpit, but it was looking a bit sparse...

I set about making a set of seats out of one of my favorite materials ever, DEPRON!!!

It was a simple case of gluing, sanding, sculpting, sanding sealering, sanding, sanding sealering again, and painting.

Too easy eh? The end result isn't as good as I was hoping for but it does the job.

While in the cockpit, I added some control sticks made from antenna tube heat treated to the right angle, and added some colour to the tub.

What seat is right without Seatbelts? I couldn't NOT do it, and for an hour's work with some 1/4" black elastic and a can of red bull for the aluminium buckles, the result is pleasing enough for me.

Next time, more on the wheels, or lack thereof!
Last edited by Curare; Apr 22, 2009 at 08:47 PM.
Apr 22, 2009, 09:11 PM
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The wheels fell off!

Okay, so as you might remember I said I went out and bought a set of scale-ish oleos, and they work, but after 2 weekends of trials and tribulations, I've run away from the idea, almost altogether, however let me regaile you with tales of woe, and you might learn something along the way, entertaining and educational!

Okay, so the oleos were fitted by cutting the existing legs off at the appropriate height and using the grub screws, I assembled the plane, with it's bare legs showing, oh lala! They proved to be a worthwhile additiion, if a bit heavy..

So obviously the next step in the process is make some fairings for the legs, (as the old ones were cracked, and in hindsight a little bit useless) No problems here, just some balsa ribs, with a cover of thin acetate and a spray of white paint, voila!

All was looking well at this stage, so I thought I'd rebuild the pants to suit. Now ever since I saw the pants, I had issues with the fact they're really only half pants, and they don't follow the scale shape. So once again out with the vac former and I knocked out two quick moulds to finish off the bottoms of the pants, upon joining them, and filling the gaps with a mixture of epoxy and microballons, I found that I must have stuffed up the ratios as it didn't go off, I just had rubbery goo for a filler. *Cue Curare Screaming in the workshop, and returning to the house to drown his sorrows*. After MUCH kerffuffling and re application of the filler, I got to a point where the pants were looking good. I mounted them to the lower (sprung) half of the legs using a screw into the boss for the axle and an ordinary wheel pant bracket.

Okay, so we have a nice set of sprung gear, that mimics the real CAP pants. WOOHOO.

It's saturday morning, and it's been 2 weeks since the test of the gear, and much hard sloggage on the pants. I assemble the beasty, and proceed to roll her out to the starting stocks, only to be stopped after a 3 foot roll. I look under the wing and see BOTH wheel pants at right angles, looking like Charlie Chaplin's shoes. Great, all the on-again-off-again, screwing of the grub screws has chewed them out to the point that they grip about as well as if they were attached to cheese. After much cursing and swearing I found some bolts that were the right thread and fitted those instead, tightening them until my eyes bled. A quick roll proved them to be satisfactory, although the fairings were looking less that pretty now. I quick takeoff roll ended abruptly when one of the pants tucked under a little and the wheel virtually rolled over it, pretty much like tripping on ones pant leg. This in turn snapped the stinger off the muffler, and only added to the embarassment.

It wasn't all bad though, I still managed to get 3 flights in with no stinger and by now very grubby messed up fairings. On the fourth flight I was showing one of my students how to enter and exit a spin, when all of a sudden I see something launch itself from the plane. Oh great, bits are falling off! A quick low pass showed one wheel pant, and one lone fairing.

I quit the engine and glided in one wing high, trying to stop the leg from touching for as long as I could, and manged to land almost without incident. A close inspection showed that the alignment bolt (loctited in) had sheared off, allowing the spring to push the wheel and pant right off the plane, mid air.

Upon getting home I decided promptly that the scale oleos were CRAP, and not worth the bother or the extra weight.

But what to do now? Tune in next time to see what I'm doing...
Last edited by Curare; Apr 22, 2009 at 09:17 PM.

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