Topic: Great Planes 1/3rd Extra 330L build

I was looking at that engine too .  Did some research and they appear to be powerful but have a tendency to seize if overheated. 

Should be okay though, just make sure it gets plenty of cooling air.

I am in a similar quandry for a 33% extra ( the Hangar 9 one at 97" span)  Prototypes were flown with a Zenoah 62 and 80cc twin although the guys in the USA fit DLE111s.

My 35% Extra 300 at 107" and 27 lbs is overpowered with a DLE111 so the little un at 10" smaller span and perhaps a  pound or so lighter would be mental.  I put wanted ads out for a 70-90cc single but people are asking silly money for used ZDZ / 3W lumps.  Just wish the chinese would make an engine in this range.

Lookin good BTW

Thanks Simon

The target weight for this is plane 22lbs so a DLE111 would have been well over the top. The whole ethos behiond the design of the model is low weight and the instructions warn about the danger of over powering it. As I said previously, there were reports of wings folding in the states due to, I suspect, over powering.

I'll keep my ear to the ground for suitable engines for you.

Ian

Ian,

I did some quick number crunching and reckon that subject to the muffler and batteries used in your fit out you will need an empty airframe weight of about 14lbs to acheive your target 22lbs finished.

That is indeed very light for a plane of this size.

Keep up the good work, great to see proper building 

Ian,

I did some quick number crunching and reckon that subject to the muffler and batteries used in your fit out you will need an empty airframe weight of about 14lbs to acheive your target 22lbs finished.

That is indeed  light for a plane of this size.

Keep up the good work, great to see proper building 

....14lbs...I'm up for the challenge.... ......the wings, fin/rudder & tailplane weigh 4lbs so I've got 10 to play with...we shall see.

Speaking of adding weight, this bad boy arrived today....



All I need now is some operating instructions and a silencer. I've e-mailed Stuart Mackay, so I'll see what he comes back with.

Back to the model and I fitted the tailplane and checked for alignment..



All seems nice and square and level so the mounting bolt holes were drilled and tapped as per the wings.



More soon....

As I mentioned in an earlier post, the Moki is longer than I had originally set the firewall up for, so first job tonight was to get out the trusty jigsaw and whip the front end off to the required length...



A new firewall was made up using 1/2inch ply. I had to extent the top to cover the top mounting lug. The offset was adjusted to compensate.



The hole in the centre is to accommodate the choke mechanism which just sticks out beyond the back line of the lugs and to allow for intake air to be ducted from inside the fuselage.  I know Zenoah engines are sensitive to air intake position and benefit from the intake being sealed off from the turbulent air in the cowl. I assume this engine is the same and will come up with something to allow this. Below the firewall is shown with the engine in place.



Has anyone got any thoughts or comments before I glue this in place?       

Wow mister, that's a big one..........

Wow mister, that's a big one..........

You're not the first person to say that to me Brian.....

Bit more progress. The firewall was glued in place and I couldn't resist bolting the motor on...



With the motor back in its box the firewall was further secured using 1/8th x 1 inch dowels..



I made a start glueing the sub formers on that will eventually hold the sheeting that gives the Extra its shape.



More soon.....

More progress over the weekend.......

First shot shows the rest of the formers fitted along with the motor bolted in place so I could get some dimensions off it for a custom exhaust.



Next shows the stringers attached. Not sure whether to fly it or paddle it!!......





Next job is the forward fuselage sheeting.....

Started on with adding the forward sheeting by glueing two 3 inch sheets of 3/32 balsa together and fitting to the lower half of the fuselage. Bit of a wrestling match this due to the compound curves, took me a good couple of hours to do everything, but I got there in the end....



Next the wing tube was slid through from the inside to mark the wood and slowly cut through. No need to be super neat here as it is only done to allow the wing to be positioned, the sheeting will be cut away to accept the wing root.



Next, the other side was skinned and the wing tube hole cut. Finally for tonight, the rear locating dowel was fitted in the same manner as the wing tube....



More tomorrow.....

As promised more action tonight...

The left wing was attached using the wing tube and rear alignment dowel and butted up to the fuselage skin....could have done with a higher roof!!



A tool was made up as per the instructions to use for cutting the skin. Never done this before but one of the joys of this hobby is that even after 40 years of building models of one sort or another, you never stop learning..



The skin was slowly cut out and eventually the wing was in its correct place...



Because the wing is tapered you end with a gap around the wing of up to 1/8 inch but the full size has a small fillet around the wing which I may replicate...we shall see.



This is what the finished cut out looks like. Note the repairs I had to make due to cack handed cutting.



The other side was done which much less trouble....more soon

What a good idea, that bespoke home made tool I mean, I have just the job for that, thanks.

Bit more tonight....top sheeting added to fuselage sides..



Next, strengthening was added around the wing cut outs using 1/8 square balsa CA'd in place to give a nice tough edge.



The instructions call for the whole model to be covered in film but I think I am going to have to glass the sheeted areas on the fuselage to strengthen them after I managed to put my finger through the sheeting whilst handling it. Easily repaired now but a nightmare once the covering is on.

More soon....

This has inspired me to build a model. Where did you buy the kit from? or did you just buy the plan and source the wood yourself?

Hi Dom

I got the kit of e-bay but it has been discontinued by Great Planes now.

I may be reading your post wrong but would this be the first model you have built from scratch? If so, maybe you need to try something a little simpler to start with until you build up experience and confidence. I'm sorry if this sounds a little condescending but I have seen too many people bite off more than they can chew and end up with an expensive mess.

Ian

Hi Ian,

I would buy a smaller kit. Sold my beloved 50CC Yak54 as it took up so much space. Your model is even bigger!

Just interested to know where to buy decent kits from. By all accounts GP kits look decent quality and I fancy doing some building next year.

I have mostly assembled ARTF kits but as I have most power tools in my shed its time to make some use of them. Would be after a 20-30cc size 3D model to build ideally from a kit with all the parts already lasrer cut etc.

One kit you might consider is the Modellbau Funtana Pro available via Probuild, see this link:

http://www.probuild-uk.co.uk/Exclusiv-Modellbau-Funtana.html

I built one of these a few years back for someone and they are a fabulous model to build and pretty straight forward. The instructions are in German but Probuild will send you a very good English manual. Eye wateringly expensive, but quality.

If you fancy something scale try Glens Models, http://www.glensmodels.com/

They do a good selection of models around your size. Never built one but heard good reports.

Finally, you could do what I tend to do, keep an eye on e-bay for the odd bargain

Ian

Bit more time on the Extra today.......

The next stage according to the instructions is to add the forward upper decking but as this begins to restrict access to the interior, I decided to fit up the engine controls and fuel supply to see if I would need to make any special arrangements especially for actuating the choke. There are two cut outs for servos at the forward end of the servo tray which I assume are meant to be for throttle and choke but it is not mentioned in the instructions or on the plans. I will decide whether to use these or mount the servos in the engine box depending on where the balance point comes out.

I had to cut the firewall away to allow for the fuel line and the throttle control rod was attached using a ball and socket.



On the other side, the choke actuating arm which has to move through 90 degrees was attached using a bowden cable. This gives a nice free movement throughout the required range.



Finally the formers and stringers for the forward decking were added.





The skin for this was made up and left to dry before fitting.

More soon.......
 

On to the top forward sheeting. The pre prepared 3/32nd sheet was wetted and weighed down to shape it to the fuselage as per the instructions. Not sure about this, I prefer planking myself but we shall see.



While that was drying and because the next stage is to install the rear turtle decking which will limit access, I decided to run the servo leads for the twin elevator servos and single rudder. These were simply ty-wrapped through holes drilled in the formers.



....and pulled through to the appropriate positions at the rear



Meanwhile the front sheeting had dried and assumed the required shape and so was glued in place and trimmed.





Back soon.....

Hi Dom

I got the kit of e-bay but it has been discontinued by Great Planes now.

I may be reading your post wrong but would this be the first model you have built from scratch? If so, maybe you need to try something a little simpler to start with until you build up experience and confidence. I'm sorry if this sounds a little condescending but I have seen too many people bite off more than they can chew and end up with an expensive mess.

Ian

Fantastic build, I'm really enjoying reading.

Although people often say start building with something simple, but one also has to consider motivation, you have to want to build it in the first place.  Thats what is keeping me going with "full tilt boogie".  If I were for example plan building a wot-4 I probably would have given up a long time ago.

Keep up the good work

CM

Fantastic build, I'm really enjoying reading.

Although people often say start building with something simple, but one also has to consider motivation, you have to want to build it in the first place.  Thats what is keeping me going with "full tilt boogie".  If I were for example plan building a wot-4 I probably would have given up a long time ago.

Keep up the good work

CM

Thanks for the comments Doc. I know what you mean but I get excited about any build. Your choice of model to illustrate your point is spooky because I have an announcement..........dear readers, I am putting the Extra build on the back burner for a few weeks while I build this........



....a Wot 4 Classic. I have decided to return to flying after a long absence and have decided that this is my mount of choice. If anyone is interested, I will start a separate topic to document the build but I will probably do bits on the Extra as fill in jobs which will appear on this topic.

Ian

....a Wot 4 Classic. I have decided to return to flying after a long absence and have decided that this is my mount of choice. If anyone is interested, I will start a separate topic to document the build but I will probably do bits on the Extra as fill in jobs which will appear on this topic.

After your extra build. Don't be silly.
Oh just got it, you were joking.

After your extra build. Don't be silly.
Oh just got it, you were joking.

ok.........you've lost me there...........

What I was getting at was who would want to view a build thread about a WOT 4 after viewing such a really good build thread that you have done so far?

Possibly......but there are some people out there as sad as me.....so I've started one anyway....

Great excitement today in the Brookes household (well me anyway!!) when this piece of sculpture arrived.......



I had been quoted £125 for a standard in cowl silencer for the Moki and so I contacted the good people at Just Engines for a quote for a custom job and this is the result. I just had to try it on the engine in the airframe.....







and the price of this work of art........£99 delivered.....

Couldn't be better Brookes, purpose made to fit. Does it have baffles in the "can" bit, or is it simply an expansion box?

Couldn't be better Brookes, purpose made to fit. Does it have baffles in the "can" bit, or is it simply an expansion box?

Apparently the pipe that goes from the engine to the can extends right through and has exit holes cut in it which acts as a baffle. Not sure if the can itself has extra baffles. Hopefully it will be reasonably quiet.

It certainly looks the part Brookes, and appears to be nicely made. 

Will building start again soon on this monster? Hope so. 

Will building start again soon on this monster? Hope so. 

Yes, I should have the Wot wrapped up today or tomorrow, so then it will be back on the Extra......

Back on the Extra at last with a couple of hours tonight.

Started by building the framework for the turtle deck....



Next the cladding was added to the firewall and the cowl blocks positioned...



Its starting to look more like an Extra now....



More soon.....

Steady progress over the weekend starting with the sheeting of the turtle deck....





Next the fin was glued into position and checked for alignment....



Next I made a start on the sheeting around the fin. I deviated from the plan here which suggested covering the turtle deck and fin area using a single sheet of balsa. I just couldn't see how this would give a neat result so I went my own way......



More soon......

Nice neat job there Brookes. Should offer a little more support at the fin root than would simply wrapping a bit of turtle deck around it. Certainly a consideration with a big petrol banger up front........

The weight penalty won't be worth bothering about. 

Nice neat job there Brookes. Should offer a little more support at the fin root than would simply wrapping a bit of turtle deck around it. Certainly a consideration with a big petrol banger up front........

The weight penalty won't be worth bothering about. 

Agreed Brian....in addition, the next bit to go on as per the instructions, is some triangular bracing around the base of the fin at the front. I guess this will help to further support the fin. The structure is pretty rigid anyway with that stern post, which is hard balsa, being epoxied to the rear fuselage former, although it will be getting shaved to the required triangular shape shortly which will reduce its strength..   

More done tonight.....fin fairing added, shaped and roughly sanded. I couldn't resist hanging the rudder on for the full effect...







Next job involves what is perhaps my least favourite part of any build......the canopy. Basically I have to build a frame and cut the canopy to size and glue it.

Several problems here...

1.      I've never found a totally satisfactory way of cutting canopies...I end wrestling somewhere between scissors and scalpels and I have ended up taking chunks out where I didn't want to. If I do that here, I'm in a whole world of hurt as they don't make them any more.....

2.     I have struggled in the past with what glue to use...I have some Pacer Formula 560.....the worlds best canopy glue according to the writing on the bottle...never used it before. I normally use medium CA as recommended in the instructions but have had mixed results.

3.     I can't decide whether to add some detail to the cockpit or just spray it opaque from the inside. I have found a nice 33% pilot figure on fleabay for a decent price so I might add a bit of detail.

Any thoughts on the above?......

Hi Brookes

I've used Pacer Canopy glue several times and I've found it quite satisfactory. The canopy? I'd simply spray it from inside. This aint ever going to be a World Champs winning scale job, and neither was it ever intended to be. It's a big aerobatic thriller, and as such I'd say it doesn't matter one jot about pilot figures or cockpit detail.......

I sprayed the inside of my Pete Tindal Excitation canopy silver when I built it a few years back. It actually looked quite eyecatching.

Hi Brookes

I've used Pacer Canopy glue several times and I've found it quite satisfactory. The canopy? I'd simply spray it from inside. This aint ever going to be a World Champs winning scale job, and neither was it ever intended to be. It's a big aerobatic thriller, and as such I'd say it doesn't matter one jot about pilot figures or cockpit detail.......

I sprayed the inside of my Pete Tindal Excitation canopy silver when I built it a few years back. It actually looked quite eyecatching.

Brian

You've pretty much read my mind on this.....if it was a super accurate scale model then I would have gone to town on the cockpit detail but I think I'm going to go with spraying. As to the glue, I'm going to try a test piece on a canopy off cut and see what I think but if its a good as you say, I'll probably go with it.

Not much to report on the model tonight and my camera has a flat battery but I spent the evening sanding and applying filler.

More soon...

Hi again Brookes.

Just remember to roughen the edges of the canopy a bit with fine sandpaper or wet & dry. It'll help the Canopy Glue to stick better. Also, if there's the possibilty to do it, I'd fasten the canopy on with several small screws in addition to the glue. As you said earlier, you can't easily get a replacement if it goes awol in flight!

Tonight's first job was to sand down all the filler down....we're getting there.....



Next job was the canopy. I first trimmed the front and rear ends roughly and offered the canopy up to the fuselage. Next, with it taped at the front,  I drew the cut lines free hand (hence the wobbly bottom line... )



Then I cut it to shape using a dremel type cutter which I generally use on fibreglass components, but it worked quite well.



Finally it was offered up to check for fit and I'm pretty pleased with the result. Once I have built the canopy frame , I can fine trim it as required.




Next is the canopy frame....back soon.....

Just out of interest, what filler have you used ... microballoons?   I've been using J Perkins' MD Products filler (7 quid for 250 ml). It's an acrylic/vinyl ester-based product. It's ok for very small cracks or as a grain filler but not much good for more ambitious filling work.

Just out of interest, what filler have you used ... microballoons?   I've been using J Perkins' MD Products filler (7 quid for 250 ml). It's an acrylic/vinyl ester-based product. It's ok for very small cracks or as a grain filler but not much good for more ambitious filling work.

I use this stuff.......



£20 for 4 litres from B&Q. Very light, easy to sand and you can use it round the house as well so the missus can't complain about the cost.....