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Focke Wolf Ta 154 Laser

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Chris Walby21/04/2020 06:37:21
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1275 forum posts
315 photos

With the upper wing sheeted I could not resist a spot of dry fitting just to see how things will look.

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And the pilot and radar operator checking their rather empty office.

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Edited By Chris Walby on 21/04/2020 06:40:41

Chris Walby02/06/2020 10:27:38
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1275 forum posts
315 photos

Still not a lot of progress over the last few weeks as its been as busy as ever, no break from normal work + all the COVID stuff to deal with and now some flying available.

Looking at the wings I managed to pin the ailerons okay and so my attention turned to the outboard (of nacelle) flaps.

The original design shows an in wing push rod at the top of the wing and is hinged by the covering on the underside. I fancied something a bit more aerodynamic in the flaps down position and have come up with this.

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The flap deflects 42 degrees which although is not barn door (high drag) was thinking should be enough. To put this in context its quite high wing loading and what I have seen have a feisty tip stall. Of course its easy at this time to relieve the wood and allow the flap to extend more thus more drag, but will it really benefit me having say 60+ degrees of flap?

Edited By Chris Walby on 02/06/2020 10:31:47

Chris Walby12/07/2020 17:35:06
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1275 forum posts
315 photos

Since the last update progress has been made...built a Woohoo, converted and tested out the new Laser lower oil fuel (very nice) and lots of flying...

And what appears to be little visual progress is not reflected by a lot of time spent in the workshop scratching my head. The problems has been initially good ideas coming back to bite me in the backside later!

The original plans were a one piece 70 inch wing and mine is 80 inch so went for a 3 piece arrangement. This generated a challenge regarding the outer flap as they are split across the join. It turned out quite elegant (for me!) with the outer wings having the out flap fully attached and so I don't need to join flaps together with the challenge to eliminate play.

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The tail and horizontal stabiliser was a departure from design as the original had a Heath Robinson incidence adjusting mechanism that appeared to be a throw back to when TX’s didn’t have trims! I thought I could lose some weight and complexity with a redesign. This was achieved but at a cost of it all feeling a bit floppy until I added some balsa blocks and sheeted it. Just a load of filling, sanding and finishing to do.

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Now back to the underside of the wing and nacelles with the decision to fit access panels to the former and fully sheet the latter. On closer inspection of the cowls I have decided to fully sheet so the engine is baffled and airflow is directed through the inlet and out through the top of the cowl when I get that far.

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Once the "other" side is complete it needs turning over and the inners sheeted and then a couple more hatches will then nearly have the sheeting completed...on the wings!

 

 

Edited By Chris Walby on 12/07/2020 17:36:44

Chris Walby26/07/2020 07:26:34
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1275 forum posts
315 photos

Again sounding like a broken record as not much visual progress, but worth a couple of photos and an update.

  • Hatches cut and fitted in the main wing where the outers plug in
  • Balsa sheeting on the underside of the main wing and flap servo holes cut
  • Balsa sheeting on the inner nacelle up to the main engine bulkhead + odd fillets
  • Engine inner cowl and baffle plus the throttle servo access cover.

On the subject throttle servo and engine access hopefully I am learning with each model build.

The Dual Ace has the throttle servo and linkage (clevis) exposed and engines mounted horizontally so its easy to mechanically adjust where as the Mossie the engines are inverted and hidden in cowls that are a right pain to get on and off. No problem as they can be adjusted in the TX...assuming I remember which channel is which engine. How I laughed after screwing up the port engine settings once adjusting the starboard end limits. frown.

So hopefully the Focke will be easier adjusting the throttle servo/main needle and getting the cowl on/off with out major effort (currently two nuts).

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….off to the shed for more head scratching.laugh

cymaz26/07/2020 11:17:20
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9272 forum posts
1200 photos

Chris

My Dual Ace has the throttle servos on separate channels. If you're not a Futaba tx user then its probably no use but I have a mixing sheet showing all the mixes to get my throttles working in unison. it also has the advantage of adjusting end points individually. As I said might not be any good but here it is

twin throttle set up

Chris Walby26/07/2020 14:49:23
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1275 forum posts
315 photos

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 laugh 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, smiley

Chris Walby01/08/2020 07:19:01
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1275 forum posts
315 photos

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_flyer01/08/2020 14:33:28
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311 forum posts
315 photos

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 larkins02/08/2020 22:25:36
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220 forum posts
154 photos

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 Harris02/08/2020 23:28:25
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9395 forum posts
253 photos

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 Walby03/08/2020 07:11:02
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1275 forum posts
315 photos

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.

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

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

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