Vailly FW 190 1/4.5 (Nick Somerville)

[Nick Somerville]

Work on modifying the engine box area is almost complete. First 20mm was cut back from the sides and the mount plate had a trapezium shaped cut out to accommodate the carb. The engine needs to be mounted on standoff’s to allow for the fuel intakes to the cylinders. Quite handy as fine adjustment can be made using washers of varying thicknesses. Large penny washers will prevent the wood compressing.  The distance between the rocker covers and the cowl is still marginal and until further work is done I won’t be sure that I will be in the clear, so to speak. At worst a slight modification to the lower shaped formers could allow a little deformation of the cowl top to bottom to give a few more mm clearance. I doubt if it would be noticeable, especially as there is an exhaust outlet at the bottom rear of the cowl for the lower cylinders. This is where I shall be mounting the Pitts style muffler.

Bottom view

The hole in the side of the box is for a screwdriver to access the idle screw.

 

Top view

 

I have a fan to fit behind the spinner and from what I have gleaned this negates the use of a baffle plate around the cylinders. Indeed if tight baffles are fitted when using a fan it can cause a drop in rpm due to back pressure. With the extra volume of air to disperse I am hoping that the lower exhaust exit, side exhaust exits and the cooling doors should be sufficient. On addition the gap around the carb will allow heated air to pass through the fuselage and out through the tailwheel area.

[Nick Somerville]

Most of the fuselage has been sheeted. Still some work to do at the fin as the plan has a different outline than that of my Bentley drawings, so some careful measuring is required before I commit to finalising the shape. The rear fuselage has taken on a decent profile having reduced the bottom of the formers to give a more accurate and flatter profile. In an attempt to save weight I used 1/16th sheeting instead of the specified 3/32. I shall use the 1/16th for the area around and below the fin too and although this will create a step as it blends to the 3/32 It should encourage  me to sand back the thicker sheeting at the rear.

 

 

These are the headers and the Pitts style muffler that came with my engine. Lovely quality stainless steel pipe. Now I just don’t have room to fit the muffler below the engine so it’s going to have to sit above which gives a clean run from the engine exits to the muffler. The outlet stubbs on the muffler will be cut back and I have in the post a further metre of the same pipe ordered from the Toni Clark website. These will route  back down to the lower scale outlets.  I could simply route the headers straight to the exhaust but I am told the Valach has a bit of a bark without the muffler and I definitely do not want to be the noisy flier at our patch.

 

[Nick Somerville]

The pipe I ordered from Toni Clarke arrived but the OD was 20mm and not 16mm 😫. Too big to bend around and achieve a satisfactory installation.  16mm is what I really need.  Anyone have an opinion on this stuff I found on Ebay.  It comes in varying sizes including 16mm.  Slightly concerned that the operating max temperature is only 300 degrees C.

 

https://www.ebay.co.uk/itm/362751491766?mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338703917&toolid=20006&var=632959133417&_trkparms=ispr%3D1&amdata=enc%3A1bbAuzn6ETpu97NN8dVvUoA37&customid=s%3AGS%3Bgc%3AEAIaIQobChMI06yHx8v4-QIVtIBQBh3cVQ-PEAQYBSABEgJ1-PD_BwE

 

An alternative is this (more expensive but up to 500C)

 

https://www.thehosemaster.co.uk/galvanised-steel-flexible-exhaust-hose?gclid=EAIaIQobChMImOG58s_4-QIVTbTtCh3wowxNEAQYASABEgI-xvD_BwE

 

 

[Nick Somerville]

Some work on the fin access panel. It’s a scale feature but may also benefit at some point should i need to replace airlines or service the retract cylinder. To fabricate the scale piano type hinge I utilised 16 fishing trace ferules and a nice fitting carbon rod I had lying around. Lighter than brass and though fiddly satisfying to make. The door has a G10 backing and this sits in a G10 lining behind the aperture if 5mm width all round. This gave the ferules a good seat to cyano in place. The door has been drilled for the two scale position fixing screws.

 

[Ron Gray]

Very nicely done Nick.

[dave parnham]

Nick if you have a look at the large Model association For Sale/Wanted section of their Forum Dave Tilbury 'The Scale Man' is after a set of plans to look at. You may be able to help him out?

[Nick Somerville]

Sorted thanks Dave. 

[Nick Somerville]

Firstly I am almost satisfied with the rear upper fuselage to fin shaping. Modified to follow a more accurate line than on the plan it’s nearly there. The full size has a surprisingly blunt lower part to the fin and this goes against my natural instinct to sharpen up the area, so I have had to be restrained.

 

My replacement 16mm od flexible exhaust arrived promptly from Hoseworld.com. Around a tenner for a metre it will do the task and looks durable (rated up to 500C. So a mount has been made up for the muffler bracket, the Pitts style outlets cut back and there is just room to route tje exiting pipes between the engine and firewall and back around to the lower exhaust exits.  Sadly my supplied flexible headers won’t quite reach the muffler in pipes but fortunately the  flexible 20mm od exhaust pipe I wrongly ordered will not be in vain,  as a short length will slip over both the muffler and headers. Quite a few jubilee clips to clamp it all up required but I am pretty confident it will work.  Why not fit the muffler below, I hear someone say. Well there just isn’t room due to the starter motor and carb protrusions.

 

[Jon H]

Thought i should reply to your pm here

 

I havent been following lately but the build is looking awesome but do have concerns about the exhaust running past the cylinder and intake plumbing.  its going to get mega hot and Ideally you want to be cooling your fuel air charge before drawing it into the cylinder so heating it up is decidedly sub optimal. I would also have significant concerns about the longevity of an installation like that with those long flexi pipes. 

 

Even if you have to sacrifice a little on the cowl to get the muffler below the engine i think it would be worth it in the long run. 

 

Do you have a photo with the cowl on? just to see how roomy it is in there. 

[Nick Somerville]

Thanks for thoughts Jon and for kind words re the build. The starter motor and carb protrusion's below the engine negate any hope of the muffler going underneath and in any case  the angles of the in and out stubs also prevent it going there, even if I ditch the self start parts . I haven’t got around to the cowl fixing yet as have needed to finalise the exhaust installation first, then I will plan the position of the cowl fixings. I have the engine out again at the moment but in this photo you can see that the exit pipe has plenty of clearance from the fuel in pipes and also conveniently passes by the black plastic sleeves so shouldn’t heat the ingoing fuel at all. Although it appears to be to be touching the cylinder fins I can also ensure a 5mm gap there too.  The pipes are heavy duty exhaust rated to 500c btw. I think my main concern was the overall length of the system, but then I suppose most of our cars have pretty long exhausts.

[Nick Somerville]

Also counting on the fan pushing plenty of cool air through the engine bay. 

[Martin McIntosh]

I remember looking at the Nats F4C winning Hurri a few years ago and the guy was relying on a fan, presumably from a turbine, to cool his engine but he had the front end in bits between flights when I saw it. Seemed to rely on airflow from behind the spinner but have no idea where it exited. I would have thought that an i/c motor would be running too slowly for a fan of that type to be effective.

[Jon H]

I think the radiant heat from that exhaust will be an issue and would look for an alternative arrangement. I know you already have that muffler can on hand but you might be better off giving each cylinder its own smaller can. 

 

Like you martin i have seen crank driven fans or impellers work in isolated cases, usually on models with inline engines. I am doubtful of their usefulness on a radial fighter with its ample cooling. I know the full size 190 has one, but this is geared to run faster than the prop and cooling 40+ litres of BMW 801 is quite a different story to cooling our model engines. 

[Nick Somerville]

Rather than keep worrying about my exhaust issues I have been sorting out a removeable part for the lower rear of the fuselage where the tailwheel retract sits. Some scraps of carbon square hollow stringers, a bit of G10 and some scraps of balsa came together nicely and the part fits with a pair of locating pins at the front and a hidden screw at the rear. This feature will allow servicing if the steering bellcrank, pull pull wires and the retract mounting bolts.

 

 
Wheel up

Wheel down

 

A pair of inexpensive micro HV servos from The Component shop arrived today so the first of these have been mounted to operate the cooling doors. I shall put these on a Y-lead as I expect to be short of channels if not careful.

 

[Nick Somerville]

I always enjoy installing radio gear, even if a bit fiddly at times. With such a short nose getting the main servos forward was a given, but I hadn’t fully appreciated just how the weight builds up. The throttle, elevator, tail retract steering and rudder servos on a removable tray tipped out at 250g, so glad it’s as far forward as possible. Having it removable allows access to fitting locknuts to the engine mounting bolts, the micro cooling door servos as well and the ignition unit. The pneumatic valve and operating servo has also been fitted.

 

I would have put the tail steering wires on with the rudder servo, but once retracted The wheel has no room to twist. Having a separate servo means it can be set to disable on retraction. 

The little block between the throttle and elevator servo is a clamp for a Bowden cable that will run to under the gun hood and will be a manual control for the choke. Enough servos and channels already!

[Nick Somerville]

With more changeable weather afoot I thought it wise to get the wing sealed. A careful final sand all over and then 48grm glass cloth wetted out with Easy Composites EL2 resin with the slow cure hardener. Gives plenty of time to work the resin in with a bit of scrap sponge and any excess softly scraped away with a potter’s rubber kidney. The kidney is the perfect  tool for this as it is fairly soft and has no sharp corners. 65ml of mixed resin needed to wet out the underside and another 30-40ml will be applied on top for the flow coat. The 48grm cloth has a nice tight weave and uses no more resin than when using 28grm cloth. I purchase this off Ebay from a company called Sewglass Products at a very reasonable price. 
 

There is a lot of detail to add to the underside of the wing, particularly in the central area, but this can be applied on top of the cloth.

 

 

[Nick Somerville]

I have had an enforced break from the workshop for some weeks but have been back on the build for a couple of days. Half the time has been spent re-hingeing the flaps. My painstakingly made hinges that I had epoxied into the flaps all had the hinge pivot points set too low; resulting in the lower leading edge snagging the t/e.  The only option was to take a razor saw and cut them off and make a jig so I could drill through the studs and fit Robart type hinges. Annoying but if I had left them in it would have necessitated a wider non scale gap.

Having cleared up that mess I used some thin aluminium sheet to simulate the hinges as seen from below.   

 

The gun hood has been hinged with a pair of Robard hinges and these, where the pivots extend above the deck, will be disguised within the front canopy frame at the scale position. Magnets have been used at the lower rear corner of the hood to keep it snug against the fuselage. A locking mechanism will be made utilising the protruding machine guns.

 

The  area at the front of the canopy needed some adjustment, so some balsa infill was added inside and then a  some coarse sandpaper taped to a large can was used to achieve the correct form. This will be skinned with lithoplate extending further into the cockpit once I am ready to finalise the instrument placing. I am awaiting delivery of both a pilot and some cockpit parts that will allow progress in this area. 

 

 

I have also ‘flow coated’ the wing after a good rub back and when this is cured and thoroughly levelled I can start to add some detail to the wing. There is quite a bit to simulate so it should keep me busy for a while.

 

[Nick Somerville]

Rummaging in the scrap drawer I found some sundry parts to fabricate a retractable pilot’s step. A simple cassette with magnets for the open and close position and a non scale tiny screw as grip to pull it out.

 

[Nick Somerville]

Made a start on the cockpit interior. Here are the made up side panels. 
 

[Ron Gray]

Those are superb Nick!

[Nick Somerville]

Thanks Ron but I only had to assemble and paint the parts as supplied in kit form by Aerocockpit. Bit of a tweezer job better suited to 1/48th plastic modellers. Who btw have my greatest admiration for their ability to work with such small parts. I just don’t know how they do it.

[Nick Somerville]

And here’s the instrument panel. Sprayed it silver first to help weather back through the grey. 
 

[Ron Gray]

I’ve just been trying some of this Rub n Buff silver leaf and am impressed with how well it can be used to apply weathering / wearing to already painted parts.

[Ron Gray]

I watched this guy using it

 

 

[Nick Somerville]

On her legs for the first time whilst finalising the wing dowels and fixing bolts. A crucial stage for any build and in this instance required several hours of measuring, fine fettling and more measurements before I was satisfied. Also used the opportunity to fit the wing saddle ply fillet bases.