CARF Yak55 SP 3.3m Build

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Re: CARF Yak55 SP 3.3m Build

Postby Dave Wilshere on Sat Mar 25, 2017 9:11 pm

Stuart.

Yes, they are epoxy and warming will allow some forming. I guess submerging would be the way, start with a slightly cooler temp and increasing. 75-80 degree water to start?

Dave
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Re: CARF Yak55 SP 3.3m Build

Postby Billy Bunter on Sun Mar 26, 2017 5:39 pm

Dave Wilshere wrote:Stuart.

Yes, they are epoxy and warming will allow some forming. I guess submerging would be the way, start with a slightly cooler temp and increasing. 75-80 degree water to start?

Dave


Thanks!

I gave this a try. (Very) hot water did help them soften, but by the time I'd moved a louvre from the hot water to the fuselage and started screwing it down, it had cooled off enough that it was back to its original shape!

So, I just used a lot of screws, which di the job!

B.
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Re: CARF Yak55 SP 3.3m Build

Postby Dave Wilshere on Fri Sep 29, 2017 11:28 am

Stuart has finished the beast, makes the 32" prop look quite small!!
A tinted canopy is planned...

Once the LMA paperwork is back he can test fly and enjoy all the work.
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Re: CARF Yak55 SP 3.3m Build

Postby Billy Bunter on Sun Dec 24, 2017 11:56 am

So I finally got around to running the engine this morning. The MVVS took a few flips to get going where the carb diaphragms were dry, but one it fired up it ran like a Swiss watch. Very, very smooth.

Next step is the maiden. Hopefully in the next couple of weeks.....

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Re: CARF Yak55 SP 3.3m Build

Postby Andrew Bird on Mon Dec 25, 2017 9:39 am

Exciting!
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Re: CARF Yak55 SP 3.3m Build

Postby Billy Bunter on Sat Mar 31, 2018 4:24 pm

Its taken me a while to get around to making this latest post. A mix of working a lot and getting back into cycling as the weather has been improving has been taking up a lot of my time.

In any case, here is a summary of the maiden:

1). The YAK55 took to the air requiring minimal trim changes
2). It flew around looking very majestic in the sky for about 5 minutes
3). A complete loss of control was then experienced, with the YAK going into a graceful dive, ending with it hitting the ground under power
4). After some careful investigation of the wreckage, I found that I had made a beginners mistake. One of the aileron harnesses, which passed under the radio gear tray, was laying against the end of one of the tuned pipes. The heat had melted the insulation on the three sets of servo wires in the harness, causing the wires to fuse together and create a massive short. In turn a couple of components in the Powerbox de-soldered themselves causing the loss of control.

The airframe was totally destroyed, though most of the gear survived.

So, this presented the opportunity to order a replacement in a custom British Flag/Union Jack scheme. The model is on the sea now, sailing its way to Europe. It should arrive in about 4 weeks, after which I will commence a second build thread....

B.
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Re: CARF Yak55 SP 3.3m Build

Postby Ally Young on Sat Mar 31, 2018 5:57 pm

Oh no!

Gutter for you man! ...and you had made such a lovely job of it. It can be a cruel hobby at times. I once managed to burn through vent tubing doing something similar and it melted the breather ...I got away with it though.

I hope all your bits are still useable ....I'd give them all a good check thuogh!

Sorry for your loss of a lovely model.

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Re: CARF Yak55 SP 3.3m Build

Postby Billy Bunter on Thu Apr 05, 2018 9:30 am

Hello Ally,

Thanks for the kind words! Clearly this wasn't the best day for me, but I did my best to take this on the chin, so to speak.

Regarding how the bits in the YAK55 faired the crash, here is a 'casualty list':

1). The tuned pipes had their fronts snapped off and stingers mashed. Both were write-offs
2). The engine came back to me, after I sent it to MVVS for inspection and repairs. There was a longer list of items replaced than I was expecting, including a new ignition,. now cylinder and piston. The bill was about 650 EUROS.
3). The Powerbox took some physical damage in addition to the electric damage from the massive short. Powerbox kindly did a deal on a replacement at half price
4). The Mejzlik prop and spinner were both smashed to pieces
5). About half of the nice Powerbox servo leads (the ones with pre-fitted MPX connecters) were torn in half
6). My carbon tray for the tanks, powerbox and receivers was snapped into several pieces

All told, including the cost of the airframe (at about £4K delivered) and some other minor bits I'll need for the replacement, I think this was about a £6K 'event', which is pretty eye-watering!

Still, I'm trying to just look forwards and remember to never make such a basic, stupid, mistake again. Importantly, the only think the YAK hit when it went in was the mud, which overall is the most important thing.

The new YAK55 should be here about the 11th April. I'll be making a point of getting on withthe build quickly and will contionue this thread as I do that.

B.
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Re: CARF Yak55 SP 3.3m Build

Postby Freestyle dude on Thu Apr 05, 2018 6:24 pm

Really sorry to see that Stuart. Lets hope the replacement brings you better luck.
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Re: CARF Yak55 SP 3.3m Build

Postby Andrew Bird on Fri Apr 06, 2018 7:59 am

It's so difficult to protect wiring in a big open fuselage with the huge heat of tuned pipes running all the way through.

Good to see you bounce back and straight on the horse again :)
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