Focke Wolf Ta 154 Laser

[Chris Walby]

Thanks for the info Cymaz and I used the same approach on the Mossie as I can't get to the throttle linkage so its easier to do it via the TX. The only issue (for me) is that I don't fly the Mossie that often and its all too easy to adjust the wrong end point in the TX. The result is I have to go back through the whole two engine set up as I have cocked up the decent one and still not set the other one up. What compounds is that its not that easy to get to the main needle as its facing down.

The whole performance becomes a bit of a chore when you just want to fly So where I can I'll make life easier. What I did find really useful was having the Mossie retract servos on separate channels and adjustable end points, great for setting them up. The Focke has all servoless retracts so no trouble there and I have dispensed with gear doors on this version. If it turns out to be a keeper then there is a growing list of mods/enhancements that can be done.

The Dual Ace dead easy, start both and when warmed up thumb in the starboard cab inlet and WOT the port/adjust. Thumb in port carb and start starboard and WOT/adjust, start starboard and just tach (tick over 1/2 and WOT for piece of mind) then go fly. All done without any adjustments on the TX (simples).

Thanks again for the info, if not used on this model I am sure it will come in useful at another time,

[Chris Walby]

A question for the collective and wealth of knowledge on the forum regarding covering, not that I am very much closer than last week regarding balsa sheeting.

The total surface area is about 3 square meters and is fully sheeted with substantial balsa. I am trying to work out the additional weight of the various options for finishing + pro's and cons of each

Bearing in mind its intended to be a scale warbird with a matt camouflage so function over glossy mirror finish + it does not need any additional strength from the covering or surface finish.

Options

• Balsa, base coat and acrylic paint with matt varnish
• Balsa , glass cloth and resin acrylic paint with matt varnish
• Something I have not thought of?

Any idea what the additional weight of the glass cloth/resin (25g/m cloth) would be? + I like the idea of the improved ding résistance of the glassing, but not if its going to add a lot of weight.

[Dad_flyer]

My experience with smaller models is that balsa varnished with no covering is very easy to dent. Tissue and dope makes a huge improvement. I have not calculated the extra weight.

[chris larkins]

The amount of resin should equal the weight of the cloth, so if the cloth is 25g/m there should also be 25gm of resin.

Or in other words 25 g/m cloth should weigh 50 g/m inc resin, so 3 square metres in theory will weigh 150 grams.

The other alternative to resin would be the water based 1-part systems, such as Deluxe materials Eze kote. This probably won't dry as hard as resin but dries in about 20 mins which makes it a really quick process, brushes can be washed out in water too.

LINK

[Martin Harris - Moderator]

Word of warning...if using water based varnish, it's important to seal the balsa with sanding sealer or you will probably find that the skin will warp, spoiling all the work you've put in to achieving a smooth finish.

[Chris Walby]

Thanks guys for the info, I think I'll go with the cloth/resin covering as most oddly with this model the C of G is too forward and any additional covering weight is likely to push the C of G back. This is despite putting the elevator and rudder servos in the tail and the engines being further back than the mossie (that has everything shoved as far forward + lead to get C of G). I can only think the retractable nose wheel is quite heavy (its very well built) and it is a bit shorter between LE and nose.

A bit of progress with sheeting in the rear nacelles and the underside side of the centre section of the wing, not trimmed or sanded, but progress.

PS worth a mention the outer wing flap which came out quite nicely in the end despite lots of head scratching.

 

Edited By Chris Walby on 03/08/2020 07:15:46

[Chris Walby]

Work continues although distracted by a short holiday and flying, well with weather like this a bit of everything (electric, 2 stroke and 4 stroke) is a great balanced diet!

Anyway back to the Focke, loads more fiddly bits and a chance to check C of G and weigh in.

Bad news is that it seems to be putting weight on (no surprise as its not finished) which is not helping the wing loading calc although at least it sits on its wheels with 272g nose weight and C of G in the right place. This is way better than the initial main U/C position that resulted with it sitting on its tail

Next minor challenge is the main U/C springs don't have sufficient stiffness due in part the mechanical ratio of the trailing arm and the fact that the springs are off a RC buggy. If anyone knows of a good spring supplier that will entertain selling less than a dozen springs then please let me know or I'll just go internet searching.

As you can see in the photo she is sitting a little compressed, but the fuz attitude is ok once the dampers are fully extended.

Just thinking of where to put the tank vent, initially I thought on the outside the of the plastic cowl...then thought how about in the dummy engine bulkhead (between the spinner and the plastic cowl facing the prop). Yes its pointing forward, but it would be a lot of disturbed air. Does not make that much difference from a install point of view.

Time to head to the workshop again, just hope someone finds this interesting...

[Ace]

Chris, "Interesting" - absolutely, just sitting in the wings as I have nothing other than praise to add, please keep it up

[Chris Walby]

Thanks Ace, update time.. uprated springs on order so will just have to see how easy they are to fit or a bit of fettling to get them to.

I still haven't concluded the mystery of why the Mossie has the RX battery, brass spinner nuts and some lead to get the C of G forwards to the right place and the Focke needs so much rearward weight to get C of G in the right place.

I suppose looking at the two side by side the Focke has the front retract very far forwards + long nose and is short in the tail compared with the Mossie. My Focke looks a lot longer in the nacelle so I wonder if the designer had a bit of artistic licence moment.

The nacelles do bolt to the wings so the Mk1b could have shorter ones or I ditch the very nice nose retract but I'll decide that when its all covered....or find a very long runway.

[Jon H]

What sort of weight are you looking at? as long as its around 15lbs im sure it will be fine.

I dont sorry so much about weight these days, i do what i can to make it as light as possible and then its in the lap of the modelling gods. I wanted my little Hurricane to be around 8.5 lbs and was disappointed when it ended up at 10. A few test flight later and it was whittled back about about 9.5 but as it still performs nicely i dont really care.

I also bought a big mustang recently and was faffing about with it in the garden. Bare airframe with retracts and oleos was 16lbs, so my initial idea of 20lbs flying was out the window. Its going to be 25 at best but as the flaps have an area best measured in square miles and the wing has a really nice section i am not worried. Videos also show it being well behaved even at near 30lbs so its not a huge problem.

As for the springs, while faffing about with the Mustang the other day i was looking at spring tension and i have started to lean towards looking for 50% compression of my oleos with just the weight of the model. It was my stampe that put me on to this idea as it sits at about 75% compression with just the weight of the model and yet it does the smoothest takeoff/landing of any model i own. Yes the model is well behaved and can be planted smoothly, but even if i catch one wheel on a bump it will just shove that wheel out of the way and not unsettle the model. Anyway, i trimmed back the oleo springs and thought i went a bit mad as they felt well soft, but a check on the scale at work revealed they needed near 19lbs per leg to fully compress. As each main leg will probably only see 40% of the model weight static i can probably make them softer still. Time will tell, the model is a long way off being built even though i look at it longingly every day!

[Chris Walby]

Thanks for the information and as a new boy to this hobby all information is helpful on the quest for progress. There are some on the web who concur that high wing loading figures are only part of the story and then discuss cubic wing loading and at that point I just head to the shed.

I'll double check the Vulcan wing loading (12lb and 69 inch wing span) as its well under powered (twin electric pusher and the builder made it very heavy), Dave says it flies very well and it looks very scale in flight so there is hope.

Its just that nagging details like the mossie has more wing area and a thicker wing (40 oz/sq ft)....and is lighter, but thinking about it the Focke will not be that much heavier. Its a double whammy with less wing and greater weight that pushes the wing loading up. I should stop worrying about it and get on with the building...

Thanks again.

[Chris Walby]

Back to the main UC, so a bit of internet searching came up with "SpringMaster" nice website and a British family owned company (not many of them left!) and so a couple of different sizes ordered to cover the postage. Order was quick, frequently updated and delivered in 3 days from order.

Top in the picture is the old damper with the spring preload space that was just not man enough with the weight of the model (yes Ken I know you did warn me when you made the arms/legs). I need to make some new caps up that hold the springs on the rods as they can move about a bit.

Proof in the pudding. Well spot on and the model now just sits and lightly compresses the springs which helps the AOA of the main wing and looks nice. Some of the full size photos show it sitting very nose up, but I don't know if there was a lot of nose UC travel, a lot of aft fuel load or designed some very fat pilots! Also worth bearing in mind the first few prototypes were tail draggers and they only changed due to pilots complaints about their very poor view when landing at night!

Now back to the balsa...unless we get a Laser Hurricane moment on Sunday

[Chris Walby]

Well its been a few weeks with lots of activity, but not with this Focke In short I am one model less that was proving quite frustrating for all parties involved. Gained a little tiddler (80 size!) and had a couple of engine issues by far made worse by me. Actually there was nothing wrong with one engine as it was a fuel contamination issue.

Back to the job in hand and trying to get my head around the back end of the model and horizontal stab and still not happy with it. Need to something with the cockpit which I think I'll rough out and go with that for the time being.

I have finally made a couple of decisions, firstly to glass the model and secondly paint with a basic high viz colour scheme. If it flies okay then it will get the full paint job later. The rational is that the glassing will have to be done anyway and I made a TN Ta 154 with the "leopard" pattern and in the winter sky it was hard to see at best. If it went below the tree line it would just disappear (funny that camouflage working so well).

Another model to finish and then on with the glassing...after a lot more rubbing and filling that is..

[Chris Walby]

The baby Focke is all finished and had its maiden (VQ with a Laser 80) although the 3 1/2 hours searching the maze field to find it was a bit of a trauma before the rain set in. I have a weird engine issue that needs sorting and note to self....it glides very well!

Two things to report on as I make steady (slow) progress

Cockpit detail. I do have a full set of detailed images of the instruments and controls and did think about going the hole hog and then thought "stand back" scale would do me for this version. A few bits of balsa and some SLEC gauges seems to have the right effect for me. Depends on how clear the canopy will be anyway (could just leave the backing film on for that opaque effect). It was intended to be easily removable for RX battery, however that's not needed as the C of G is so far forward it can be screwed down.

Bit the bullet and started glassing using the credit card technique.

Lessons learnt

• Don't use the better half's kitchen scissors
• Buy a couple of pairs of scissors (glass cutting and trimming wet glass, they don't mix)
• Once the resin starts going off bin it and don't rush...I did glass a couple twice on one side...aarr
• Mix the smallest amount possible and be prepared to waste half of that! (mixed 15ml!)
• Using balsa block seems to stop the resin soaking into the balsa like mad
• Another 30 years practice and I might be passable at this

That lot has gained 91g so well happy with that.

[Chris Walby]

Wow the best part of a month and no update, how tardy and what excuse do I have, well it can’t be flying getting in the way as I haven’t flown in two weeks either.

I have been beavering away with glassing, first the underside and then working around to the top surface.

Parts on the to do list

1. Elevators
2. Ailerons
3. Outer wings
4. Outer flap
5. Inner flaps
6. Rudder
7. Centre wing with nacelles
8. Fuselage
9. Rear access panel
10. Front access panel
11. Upper wing panel

Progress to date includes items 1 to 6 and 9 to 11 glassed on both sides with one coat of primer on the outer wings.

More lessons learnt with glassing

• Flat surfaces are easy, curves are harder, compound curves tricky and convex are best singled out for special (separate session) attention
• Ensure excess resin is left on the edge or at least make sure its fully wetted at the edge, makes life so much easier when trimming
• Get all the bubbles out…or lots of re-work
• Don’t cut fibre hinge slots before glassing….they fill with resin

Just lots of rubbing down, filling and more rubbing down to do. Then sorting out the hinges again and masking up for the primer coat. It would appear I appear to have plenty of time to do it as the flying field is closed, but there lots of other things to do + work

Edited By Chris Walby on 08/11/2020 06:43:52

[maurice northcott]

Nice work Chris. Very interesting thread....

[Braddock, VC]

[Chris Walby]

Update time as with no flying due to Covid you would assume plenty of time for building however work is very busy with end of year activities and yet more new ways of working to deal with.

From the glassing activity and a coat of primer its become very evident that there are a lot of lessons learnt around finishing. Minor blemishes at glassing stage become very apparent once the primer has been applied.

This brings me on to bigger and more concerning things which is the AUW and C of G. On the latter and as mentioned earlier I was really court out by a forward C of G without ballast. With the Dual Ace it was just nose heavy and the Mossie’s it all about getting enough weight forwards. Its weird as the Ta 154 is shorter in the nacelle than the mossie hence I thought the weight of the 70’s would have less effect, but completely underestimated the effect of the super beefy nose retract and longer fuselage in front of the LE. The other thing is its shorter from TE to tail which has conspired to increase to the problem.

Pre glassing it needed close to 400g in the tail and with the primer on things are better in one respect. The C of G is where it needs to be, just the tail ballast has been swapped for glass (minor) and paint (major) weight gain. Now this is all pre rub down, fill, paint, rub down and final top camo paint, but I think I am close enough.

[Chris Walby]

On to the topical subject of the maiden (still a log way off with lots of bits to do) I have decided on a high-vis approach due to the nightmare flying of my TN Ta154 in leopard style pattern. With a winter sky and get it close to the tree line/horizon and it would disappear (funny that camouflage stuff doing that). Hence like it or loath it this is its maiden scheme and if it flies then the rest of the winter can be spent completing the camo pattern and putting the markings (care of Callie Graphics).

If it gets last its maiden and flies like a manhole cover if have an option up my sleeve that does not require extensive modifications to decrease its wing loading.

[Tim Flyer]

Very impressed. Great work!

[Chris Walby]

Last weekend was rather foggy for flying, well very poor visibility and the near freezing fog played havoc the foamy things being flown. The backing on Velcro would not stick and the paper covered foam absorbed lots of water. The lipos were struggling with near zero temperatures although the day was marked by achieving the same number of flights this year compared with last year. Just goes to show if you pick the nice days to fly what can be achieved, failing that just fly anyway.

Back to the build and the focus on control surface linkages and gluing the hinges which just seems to take an age to do (not helped by a cold workshop).

To do

• Elevator – two servos to link the control surface with pin hinges
• Ailerons – two servos to link the control surface with pin hinges
• Outer flaps – two servos to link the control surface with fibre hinges
• Inner flaps – two servos to link the control surface with fibre hinges

So senior moment when I realised I was two flap servos short so got some dispatched from Inwoods and then once the outer wings were sorted…found a pair tucked in the inner section, doh.

I am working on the principle of maximum lift with the flaps (fully extended in the photo) as it should be quite draggy with the props and gear down.

Now I wonder where I left the servo reversers….

Does anyone have advice on Robart pin type hinges as I was intending to use 5 minute epoxy but want to prevent gluing the hinge pin by mistake?

Edited By Chris Walby on 12/12/2020 16:55:06

[alan p]

Dab of vaseline on the hinge knuckle with a cocktail stick usually stops any stray epoxy. Depending on number of hinges per control surface you may prefer 15minute gives time to align hinges and clean any stray elsewhere with meths.

[Chris Walby]

Festive greetings to all and as expected visits have diminished to the garage in part due to the weather and festivities.

Thanks to the advice from Alan P the pin hinges are now epoxied in, move freely and are solid, cheers.

Earlier in the year I added a VQ FW 190 to the hanger with a Laser 80 mostly as a distraction to the current build. The original spinner lasted about 3 starts before disintegrating with a bang which was a bit concerning. I get the impression that manufactures are making spinners that are electric rated then the more arduous life of a ic spinner. It seems there is a real shortage of 70mm FW style uncut spinners (my FW 190 is 3 bladed and the Ta 154 currently 2 blades). After a flurry of messages to one of our youngest club members with a “that’s easy” (well it is for him!) and a few CAD images later and trial print was activated.

[Chris Walby]

cont

Building is still progressing with cowl cutting and fitting – done, but I don’t like the solution so there will be a mark 2 version. The cowl needs to be easily removed along with the baffle so that I can access the slow running needle. I have no intension of twiddling with it, but if its accessible than I won’t need to and the main needles are easily accessible anyway.

Jobs to do:

Tail and wiring loom over the next couple of days and then a through inspection and check over.

Might even get around to some engine testing next week.

Merry Christmas and Best Wishes for 2021 + thanks to the +4000 views (whoever you are!)

[Eric Robson]

Hi Chris, I have a VQ Hurricane, the 60 size one . I used electric power and on a low pass the spinner disintegrated , I landed safely. One of the 4000+ Best wishes to you too.

Eric r. not much faith in VQ spinners. 

Edited By Eric Robson on 27/12/2020 11:01:25