Focke Wulf 190 F4C 1/4 Scale

Sam some designers use abit of artistic licence when drawing plans. Trying to keep it "to scale" is very time consuming and is also dependant on them have the scale information at the time, if not they guess it and hope no-one notices. Other times it may be necessary due to limitations imposed on replicating the protoype with materials available to the modeller and the need for strength in the construction.

Not done much for a bit due to work being extremely busey but I did manage to fit the removeable 1.5 litre fuel tank (5 cylinders draws alot of fuel ).



Also played around with the tail wheel retract which is turning into a nightmare with the pull pull set-up. I am awaiting Probuild to send me some ballrace clevis and APC in the USA are sending me Kevlar plastic coated cables. No fear of breaking or radio interferance The wheel in the photo is a dummy, used just for alignment and will be replaced with a scale 3" wheel from Glennis (USA).

it all looks very impressive ,hope you do well in the shows.

Yeah!

Thanks John and Sam.

The problem that I have encountered is that the plans are drawn for a fixed tailwheel, when the full size had a retracting unit. Sierra Giants Scale retracts in the USA developed a true scale retracting tailwheel for the Vailly FW190 which you can see in the photo. They are of excellant quality but a bit pricey and are air operated.

The issue for the full pull cables to turn the steering tiller is:

When in the down position the cables need to be just taught, to stop the wheel from wobbling. However in the retracted position the tiller moves 2 1/2" upwards. This means that the cables need to follow the tiller and stretch by 2 1/2"..... errr no way To overcome this I have had to run the cables so that they at a pivotal point 1 1/4" from full up and full down, which means that they will be just taught in either position. However the pivotal point is right ontop of the retract mounting which will require "snake tubes" to hold the cables in position. It also means that the cables and linkage will be angled at 30 degree in the up and down position. This then creates a problem with being able to pull the cables at this angle using conventional pull pull linkages. After some searching on the web, I managed to find that Probuild in the UK (makes a change from the USA) import some very nice roller bearing pivoting linages which are an import from Japan. They are just what I need and awaiting delivery. Price, over £10 each (I need 2) .

WOW very expensive!!!
Can wait to see her all together in one piece and that 5 cylinder engine fire up and roar like a beast!
WOW

These are from Hobby King, they haven't any in stock at present but worth a look for the future & only $2.99 postage

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=9216&Product_Name=Clevis_With_Arms_M3___M2xL24mm_(5pcs/bag)

Thanks Richie, shall bear them in mind for the future. Mine are actually 2.5mm not 3mm but very similar. I'm not suprised they are out of stock and not suprised by Probuild prices, has a reputation for his prices being a little on the high side

if you order with hoby city they will email you when there in

Actually it as over 1,000 .............. yen (1,115 = £7.63) Probuild charged just over £25 including shipping within the UK. The quality is excellant.

Well since it's too cold for the glue to dry, only been able set up the tailwheel linkages. Progress is slow.

Haaaa pesky cold ness!!!

Is the tailwheel connected to the rudder at all, or have they both got seperate linkages Richard

Seperate servo's. Using a retracting tailwheel causes issues with the rudder being moved with the tailwheel in the retracted position. It could jam the wheel and not come down for landings. The TX retract switch will turn the tailwheel servo off, in the retracted position but a mix will operate both servos in the down position on the rudder stick.

The tailwheel installed with the pull-pull set up showing the view of the snakes as guides for the cables. The ends of the snakes have been melted over the gas cooker (don’t let the wife catch you doing this, as it makes a smell) and pressed against a bar to expand and round the edges so that they don’t cause abrasion. The advantage of using PVC coated cables is that daylight (UV) deteriorates kevlar and it becomes brittle overtime. PVC is an effective barrier, makes the cables run smoothly without cutting into the snakes and no “radio interference” concerns commonly associated with wire cables.



This photo shows the tailwheel in the retracted position and you can see the angle of the linkages and the advantage of using the roller bearing clevis.



The photo is showing the tailwheel in the down position.



Next was the stab positioning and is a similar procedure to setting the wing. The plans call for the tailplane to have “one of degree positive incidence”.



The process was:

1. Set the fuselage datum to a zero incidence in two horizontal axes, using a calibrated spirit level. You can see the cross axis spirit level above the cockpit area in the photo. This same axis was also double-checked at the tailplane and engine firewall (no twist in the fuselage). The longitude axis was checked along the length of fuselage crutch.
2. The stabiliser was then placed in position. Due to its airfoil, a spirit level couldn’t be used to set the horizontal axis. Instead measurements where taken at each wing tip to the workbench below. Both measurements were found first time to be the same, so no need to shave the stabiliser seat for adjustment.
3. The incident meter was then used to check the incident and was spot on at “one degree positive” also without the need for any adjustment.
4. The last measurement required was the plan view. By running a measuring tape from centre of the fuselage longitudinal datum to each wing tip, the stabiliser was twisted so that both measurements were the same.
5. All measurements were then double-checked again. Once happy, the stabiliser was marked in several reference points to the fuselage seat and then glued into position using 30 minute epoxy which provided time to re-check the incidence and measurements before the glue dried.

Engine cool vents

The FW190 has three cooling vents on each side of the rear engine area, behind the exhausts that could be set by the pilot. On models that I have seen they are commonly shown as three closed panels drawn with a felt pen. Satisfactory for stand-off scale but not for F4C competitions .







I need as much air as possible to escape the cowl to protect the "Moki" and the extra airflow exit would be very welcome. There was no option given on the plans so after a bit of head scratching I came up with the following idea which seems to have worked out very well, even to the extent that I could make them functional to open or close with a servo. I shall fix them in the open position.

I had the opportunity to visit an FW190 restoration in the USA where I took more than a few photo’s, one of which was fortunate to be new vents panels being fabricated on the work bench.



Using the KIS principle I only need three parts to make the aerodynamic panels. A hinge made from 4mm dowel and two pieces of Pro-Skin for the surfaces.



At the actual location for the vents the fuselage has a curve and when scaled down from the full size prototype is a bit more pronounced on the model. My first attempt with a straight vent panel was frankly a disaster and found it’s way into the bin, never to return . The second attempt was to try and set the vent panel with a curve that would not be lost and provide a scale fit, which the straight panel attempt was anything but. The fuselage former, that just happens to be at the scale position, provided an ideal template and the dowel was soaked for ten minutes in boiling water (ammonia is best, but I haven’t any) and then clamped into position and allowed to dry.



Without removing the dowel the top Pro-Skin panel was cyno into position on top of the dowel and effectively locked the convex curve into the dowel. It was then removed and the bottom Pro-Skin panel was then cyno into position with a concave curve. The vent panel was now complete … KIS

All that was left to do was to mark and drill the positions for the dowel through the side fuselage stringers, which also happen to be in the right place at the right time. The dowel was then positioned as a hinge and the result was an operating vent panel that was flush when closed and retained its shape when open. Note the fuselage has been painted black behind the vents. Won’t be able to do this later





Now I only have to do it another 5 times and make the fuselage panel to go around them. I shall post some photo’s when finished.

Happy New Year everyone.

And finally ....

Nicely done!

At the opposite end of the tailwheel is this bell crank that I fabricated so that the pull-pull cables are parallel at all times. This provides a perfect set-up with no slack at anytime in the cables. I recently posted an article on the forum about Pull-Pull Cable Systems in “How To” section which some may find interesting reading.



The photo is obviously a mock up of all the parts before they are fitted in the model.



Some points that may be of interest are:
(1) The cable ball links are the same distance apart to the tailwheel tiller. (2) The use of PVC coated Kevlar cables will not deteriorate from UV light, have no stretch and are quoted as lighter and stronger than steel cables. No concerns over radio interference associated with steel cables. (3) I find “threaded eyes” are far better than conventional R/C cable connectors which are a pain to adjust (4) Lock nuts are used to make sure the “eyes” don’t rotate, loosening the cable. (5) As this is for a tailwheel, the cables are spring loaded to take the shock off the servo, over rough ground. Finding the correct spring rate was an adventure. They mustn’t be weak so that they stretch when steering or too strong they don’t give any shock absorbing effect. (6) The use of a remote servo also helps item 5 and allows the servo to be mounted in a more convenient position off centre, where the rudder servo/pull-pull has also to be fitted (slightly higher and further back position that will not to interfere with each other). (7) The servo rod works as a turnbuckle, with left and right hand threaded ball links. This allows minuscule adjustments by turning the rod one way to lengthen or reduce. ( You can buy lead crimps from fishing shops (anglers use them for tackle set-ups) or use short lengths of brass or alloy tube, my personal choice is the latter (they haven’t been crimped for the purpose of the photo). (9) In the background you can see that I have used heat shrink to lock the plugs join of the cable extension to the servo lead. Far better than tying with floss or R/C plastic clips. (10) The bell crank mounting is removable for servicing and I have used socket head servo mounting screws. Far superior than conventional posidrive servo mounting screws, that always seem to refuse to budge when removing, rounding off the head! You can get them from www.modelfixings.co.uk.

Next job was to set the wing chord saddle and fairing, another headache. The saddle itself isn’t difficult but the fairing around the leading edge is impossible to do, if following the plans. You can’t get the ply saddle to mould itself around the leading edge so that it will look like this……..



It has to stop above the leading edge, which leaves an unsightly and non-scale lip. I’ve come up with a solution that will have to wait till further into the build but basically the idea is normally to have the whole fairing on the fuselage. I intend to have 2/3 on the fuselage, running forward from the trailing edge. The front 1/3 will be moulded onto the wing, eliminating the leading edge problem. My only fear is hanger rash when transporting. To get the perfect saddle fit, the sides of the fuselage were left unsheeted so that I could get at the inside of the saddle and apply pressure down onto the wing and Zap CA, not forgetting to put some cling film over the wing so that it doesn’t get all glued together.



The tail fin and tailwheel air cylinder mount was next job. The rudder is left for later as the fin and its trailing edge shroud will dictate the final size and shape of the rudder leading edge. It is very difficult, if not impossible to make the fin fit the rudder. These are the components.



Here the air cylinder can be seen mounted inside the fin. A scale hatch will be made for access after it has been sheeted and fibreglass covered.





You will probably note the old faithful cling film protecting the fabric covered elevators.

The fin is sheeted with 1/16th balsa and the fuselage with 3/32”, then the top deck is sanded to shape blending with the fin leading edge. A radio mast point has still to be placed onto top of the fin, but this will be done just before painting commences.

While sheeting the fuselage I noticed that once done I would have made it impossible to fit the scale cockpit due to the size of some components and the restricted access. An example of a big square panel doesn’t fit in a small roundish hole. So I have had to jump ahead and fit the instrument panel now or it will never go in.

I’m using Warbird Colours which are ”scale” from America and Humbrol for markings. RLM66 was the factory interior colour on the late war FW190 (it looks like black in the photograph but it is actually a dark blue). The instrument panel is a three stage assembly. First the panel is painted



Second a clear acetate sheet is fixed behind the instrument holes using a hot glue gun. Third the instruments dials are then glued in place.



To help give support the instrument panel is reinforced behind with balsa and then glued into the model with Zap-A-Dap-A-Goo II. Perfect glue for the job as it stick to just about anything and wont melt the plastic like CA does and is flexible to take some of the vibration preventing the glue joints from cracking as most plastic parts will over time.



Now I can finish sheeting the decking above the cockpit and get ready to fibreglass cloth the fuselage (and try not spill some on the dash )

WOW
THAT IS COMING ALONG BEAUTIFULLY!!!
I really cant wait to see this bird fly!!!

That is quality work, shame we may not see it at the Rhyl Field

Why wont we see it a rhyl?

Richard is no longer a member of our club or hasn't yet decided whether to join

Oh I really hope he does, and if he doesnt and go's to another club, im going there to see it maiden!!!!

I'm about, fear not. Just taking a rest.