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Bates 1/5.5 Sea Fury Build


Nick Somerville
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I certainly would not affix weight to a glass cowl, you would be asking for trouble. If your batteries are lightweight LiFe you may not gain much advantage in moving them forward a little. Lipos could be another matter. I have strapped two 1600 Life packs to my Chippy motor box with suitable padding though, and so far they are OK. Not much different vibration wise as at the rear of the firewall. Perhaps a couple of brackets facing forwards with the batteries strapped on would work.

That AUW sounds good to me.

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Nick see attached rough sketch.

eyelets are the crimp/solder type and piano wire brace length is adjusted once you have found weight position and soldered in situ to the eyelet. top firewall one is already pre done so only weight end subjected to soldering heat.

Penny washers spread load but could use anchor nuts in fire wall if prefered.

Nothing attached to the cowl.

 

weight.jpeg

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Spent some time today working on an idea I have had in mind for a while. Priming an engine in an enclosed cowl needs some form of access to get the finger over the intake. I cut a hinged hatch into my P47 cowl through which I can both adjust the needle valve and finger the intake. However, with twin carbs on my Fury’s V twin Laser, even with a hatch on each side an extra hand would be needed.

 

My everyday hack model is a Wot 4 XL engined with an OS Surpass Mk 2 pumped 120. The carb on this engine has a neat priming facility that is actuated by pulling down on a length of bowden cable that closes of the intake. Once the engine has been turned over several times the cable is released and a spring disengages the air intake shut off.

 

So for the twin I silver soldered two discs of copper clad pc board to the ends of a length of piano wire and bent each ends at 90 degrees so that the discs lined up with carb intakes. Two hinge points of drilled G10 were sandwiched between ply blocks and epoxied to the front of the engine box An actuating horn also soldered to the piano wire axle. The two discs have foam rubber pads adhered to them to ensure a snug seal and a return spring added to ensure they are kept well clear when not in use. The geometry was more awkward than I expected, as the intakes are slightly angled from each other and at different distances from the front of the engine box. Hopefully the pictures will be better than the explanation. I have yet to add the actuating cable which will exit through the bottom of the cowl. Laser engines like a good wet prime, so hopefully this will do the job.

 

image.thumb.jpeg.a9cb5a3ed716667bdb563dc6f7965ee0.jpeg


 

image.thumb.jpeg.784274ee196ef6dc28911defc3dc37aa.jpeg

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On 29/10/2021 at 17:06, Nick Somerville said:

David, the Robotshop couplers came with several adaptors for a variety of common servos but unfortunately for me not one to suit my servos. O took one if the oversized ones and filled it with a epoxy mix and then places it over the splines (having first applied some vaseline). Seems to have worked fine but until I finally glue in the aileron hinges I can’t properly test everything. As mentioned they are a bit pricey and in my case even less value since I didn’t have matching servos.

 

Sorry to hijack thread again, but I found by searching for "aluminium flange couple connector" there were many solutions very similar to what @Danny Fenton designed. I went ahead and ordered these from ebay: https://www.ebay.co.uk/itm/363462983497 (I chose the gold 3mm). Five quid a pair, delivered from China. They have arrived and I'm pretty confident they will do the job although will need a relief cutting into the underside to account for the servo screw. 

 

Pictures in the google album here: https://photos.app.goo.gl/HnLMmPcCaoWhAe6m6

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Whilst choking the carb of a Laser does aid starting I’ve found that a few bursts with the starter with a WOT does the trick just as well. I’ve also tried closing off the vent on the tank for the last couple of turns when filling which forces fuel through the carb which also works (on a 3 line tank). Another method would be to fit a pressure nipple to a silencer then block off the exhaust to choke. The choking is also only necessary for the first flight of the day!

 

Edited by Ron Gray
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28 minutes ago, Nick Somerville said:

Yes the setup is a bit overkill, but kept me amused for a few hours. The carbon spinner I have came with a note suggesting not to use a starter in case the torque against a flooded engine damages the fixings ?

 

 

I would only use the choke in cases of extreme reluctance to fire. If the engine is dry and you hit it will a starter the engine will come up to the starter rpm wile fuel is drawn up. Once it starts to fire the shock through the spinner cone is very low as the engine already has a fair bit of momentum in the desired direction and the engine is firing at the right time. If you prime it heavily though and hit it with the starter the engine will fire early, with very little momentum, and this will risk damaging the spinner as it will kick back. If you do end up needing to prime it i would try hand starting with the backwards flick. 

 

On my own carbon spinner equipped fury i just go for it on the first start of the day and then on the next start i trim the throttle a little lower to minimise the kick it gets when the engine fires. 

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  • 2 weeks later...

Here is how I have mounted the lead. I bolted an alloy engine mount half to the bottom of the firewall and bent up some  3mm threaded rod to make diagonal supports back up each side to the centre fixings of the radial mount. The roofing lead was weighed (1.75lbs) and cut into manageable sizes and fixed with two 5mm bolts either side of the mount, which clamped it all tightly in place. It will be easy enough to add or remove lead as required later.

 

 image.thumb.jpeg.74f6a94d259917e813533fa478c8bcb6.jpeg
 

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Other jobs done over the festive period has been to install the fuel tank and prepare the wiring for the remote glow.  The tank is a 24oz Dubro one that is quite shallow. Hopefully this will mean the slightly low position of the tank relative to the carbs won’t be a problem. I drilled an extra hole in the bung and have separate clunk feeds to each carb, a clunk for fill and drain and a vent which exits at the bottom behind the cowl; facing forward for a little pressurisation.

 

Next up on the front end is to finalise the exhaust extension set up, but I am awaiting a couple of parts for this. In the meantime I shall work on signing off each of the control surfaces and their operations. 
 

Thanks to everyone who has been following along my build this year, I really appreciate  all the advice and kind comments. Have a great New Year and happy flying in 2022.

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Spent an hour or so today fiddling with the tailwheel retract. I have a macgregor MG 5912 HV servo, from a previous model operating it and although the holding pressure on the linkage/mechanism in the retracted position is moderately light the servo constantly grumbles as digital servos can. Does this do any harm to the servo or cause any adverse current drain? All the servo is holding is the weight of the retract and wheel in the raised position so it can’t be more than 20-30grms.

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Depends on whether you are using a separate battery or not. The system shown on my plan would rely on the servo to hold the gear in each position since there is no real locking mechanism. May be worth putting an ammeter in circuit to see just how much drain there is. I am currently installing my retracts and the tail wheel is next to connect to the matchbox to check the operation but of course it is of the locking type.

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I tend to put retracts on a separate supply if they are mechanical but an air valve should be no problem. Why use one on flaps, depending on your servo set up? If possible I try to have flap servo arms arranged so that in the deployed position they are in line with the horns so that there is zero load on the servos. I even use some TGY 180D (very small MG 180 deg.) to achieve this.

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1 hour ago, Martin McIntosh said:

Why use one on flaps,

4 servos on one channel for flaps with individual reversing and end point adjustment. As there was a battery port on the matchbox seemed ideal to use a separate battery and avoid an extra lead to the fuselage. I am using a 9 channel powersafe dual battery receiver I had bought at a very reasonable price with 3 sats. Without the Matchbox I would need 11 channels and these days a 12 channel powersafe receiver is over £200!!!

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Nick, I believe that you have done yours in a gloss finish. Looking at the museum pics of WJ 232 which mine is based on, they too look very glossy so at the moment the parts so far are in this finish. Speaking to a friend today he says that he has never seen a glossy one at an airshow. Plenty of time to tame it down to satin if needed.

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