Topic: Spitfire Mk9 build

http://plans.am.free.fr/plans/spitmk9.zip

Just downloaded and printed out this great set of drawings and am starting the build. I have photocopied the plans at 100% and pasted all the formers onto ply/balsa ready for cutting out.

I don't think the wings will present too much of a problem but I'm not sure where to start with the fuselage. There is not a lot of detail on the drawings and certainly no build instructions.

Any help would be most appreciated.

Thanks

Hav'nt seen you around these these parts Mr Caveman since your ASK 18 wing build, that was a few years ago

Hi Gary - yes I didn't realise it had been so long, in fact commented to my wife when I saw my last activity. After the ASK I found that flying was causing a lot of RSI in my right wrist/arm so decided to give it up and go to something a bit less active and built a Marblehead 1.4m yacht from scratch. It is now on the market as I find I enjoy the building more than the "playing with" so here goes a 1/9th Spitfire project, hence the advice about the fuselage build.

Err any help out there please guys?
Where do I start to build the fuselage? I have all the formers cut out and sanded etc but can't see where to begin. Should I make some kind of jig to ensure no twist creeps in?? Never built from a basic plan before so all a bit confusing!

It would appear to me that the fuselage is built in two halves, the bottom half first which is built on the plan and planked to keep it's shape then the top half is then built onto the bottom half. The centre line of the two halves being the thrust line.
It does'nt make it at all clear how it should be built thou so this is just my interpretation of it.

The lack of replies may be because the file is a DXF file and not everybody has programs to open them, could you not save it as a PDF and post that.

http://www.rcgroups.com/forums/showthread.php?t=234854

I posted this in my thread but it will be more help to you here.

Hope this helps.

Shane

Absolutely fantastic Manaconda69 (Gadmac?). Just what I was looking for. I must say the fuselage build is nothing as I expected and possibly a bit easier now that I've seen it.

Many thanks. I'll be having the laptop alongside me all the way and yes, it has taken me two nights so far just to rough out all the ply parts and sand the outsides to drawing. Now to drill and scroll saw all the inside bits out. Lot-a-fun and makes it a truly home build!

I'll start posting progress here when there's progress to report...........

Looking slightly to the future, which retracts are best suited to this. I've looked at air, servo and electric and all seem to have pros and cons. Air seem very expensive with servo the cheapest.

Also Manaconda69, did your spit build have the under wing flaps? Couldn't see on your build pictures and nothing mentioned on the plans.

I'm glad that is there to help you along. It looks to be a cool bird and I'm looking forward to seeing the build come along. I am not the author of that bird, just someone who like to help where I can. Tony's 46" spit doesn't have flaps but if you check out some of the other build blogs on this forum I'm sure you will have no trouble finding the way. most people love to help. You might want to check out a set of E Flight electric retracts as they have been getting great results and it's all built in so no fiddly bits. I think on the larger scale models they come to around £160 or so and around £69 for the smallest sets.

Someone said if you do one thing every day eventually it will be done.

Good luck

Many thanks again. Yes, quite a daunting task when looked at with nothing done. I think the longest "task" is the cutting-out/sanding all the formers etc in preparation for the build as you can't see anything taking shape. I have an old, 1970's vibra saw which does a great job but whatever saw one uses the inside cutouts are the time consuming ones, having to drill a pilot hole then thread the piece onto the blade!

I'll try and get pix on here but I find sizing them a bit awkward as my camera files end up at around 5Mb and I'm using iPhoto on my Mac Air to process them and there's no "resize" function. Maybe process them on our main computer first then transfer them - whatever, watch this space 

Although I'm going to start with the fuselage I need to look a bit ahead to the wings and decide which retracts are best suited (also cheapest?) so that I can accommodate cutouts in the ribs before assembly. These seem to be about the most expensive piece of kit I'll need to buy, and not having much spare from my pension, which would be my best option please? All air and electric seem very expensive

The hardest thing with the retracts on something like a spit is hetting the pintel angles right so that the wheels move to the right places at the right angles. If you just bolt a retract unit to bearers parallel to the wing surface the wheels either won't sit flush when retracted or won't point in the right direction when extended. If you PM me an email address I can email you another spit plan which has these accurately detailed for reference.

Depending on your personal "effort/cash trade-off" you can reduce the tedium of cutting out the parts by using one of the laser-cutting services like Lightwork (JohnB and Maz here on RCMF) who can scan the plan and cut as many of the parts as you wish from it.

I've looked at this particular plan many times over the last few years and have considered many approaches to building the fuselage. My prefered option is to add a horizontal crutch made from (say) 1/8*1/4 or 1/4sq that goes along the marked centres of the formers. This is built over the plan with a cross-piece at every former position. I would then raise this up on stand-offs so that the formers can be glued into their positions. Part of me is tempted to add some stringers/longerons at this point, but I think that might just add weight so I'm in two minds about it. Anyway, this allows the upper half of the fuselage to be planked down do as far as the stand-offs. Once the glue is fully set I would remove the fuselage from the plan and rest it inverted in some blue-foam blocks while the lower half was planked. For me this would be a better approach than splitting the formers, but different people have different views on this!

PDR

Many thanks PDR, again all most helpful. The plan I have does have some quite heavily off set locations shown for the retracts but obviously these have to be sized to the retracts one uses and the wing ribs also cut accordingly. I did think of getting a set of ribs/formers laser cut but fancied doing the whole thing myself. Also again, cost savings!

Another question gentlemen (and ladies). This drawing by Dave Philpotts I'm building to was obviously drawn some years ago and calls for a 500/600 geared electric motor 2000. I presume this is a brushed motor of a certain size and the plan is drawn to accommodate it.

What would be a modern equivalent for this guys? I'll probably have to modify the front end slightly. Also it looks like a large NiCd battery but I'd go for a LiPo probably?

Working with Steve Webb models I'm using 4 X Hitec HS82MG servos for ailerons/rudder/elevator and a pair of E Flite 15-25 90* retracts http://www.servoshop.co.uk/index.php?pid=EFLG200&area=RET

Do these look OK for the size? No real idea what it will weigh when completed but I'd like to think it will be no more than 7lbs

Servos look fine. For motors I'd go for a modern brushless motor looking for something rated at about 40A with a Kv of between 1000 and 1200rpm/v (like the Axi 2820/10, but there are far cheaper alternatives). On a 3-cell lipo this would turn a prop in the 10-7 to 11-7 range delivering 400-450watts (a 3s3300 lipo should give typical flight times of up t0o 10 mins with normal throttle usage). This setup will be both substantially lighter than the original brushed motor with nicads and significantly more powerful.

The original design is intended to use what we would now call an "inrunner" can motor. Most of the modern motors are "outrunners" with different mounting systems, and you'll need to look at the front end structure to adapt it to take one of the more modern setups unless you go for a brushless inrunner (which can be done, but is generally more expensive than the outrunner option because they are more difficult to make). But it's nothing that takes any vast effort or brain-scratching.

PDR

Also a general rule of thumb is... 100 watts per pound. So if you have a rough idea of what your model will be in weight then you can cross reference that with the number of watts a particular motor will put out. Try to get a motor that will put out more than what you are looking for. Also keep in mind that you will need an ESC speed controller that can handle twice the amps that the motor can put out. This is one of those safety measures incase of a spike in amps the ESC can handle it.

Hope this helps.

On ESCs - this depends what type of ESC you get. If you use a "Quality" one (Jeti, Hacker, Kontronic etc) then you can use the stated ratings. My 40A Jeti ESCs are routinely run at 40-45A without problems, but they are very much more expensive.

The cheaper ones have rather more "optimistic" ratings and need to be given "headroom". So if you're looking at a Turnigy/Hobbywing (the better of the budget ones) then I'd de-rate by 30%ish, so for a motor drawing 40A at full throttle on a fresh battery I'd be comfortable with a 60A Turnigy Plush or similar. The 60A Turnigy is still half the price of a Jeti 40A controller, so it's a difficult choice! Personally I'd feel that an 80A controller for a 40A motor was overkill, but different people have different approaches here!

PDR

Gentlemen, many thanks. If there's one place I can rely on for sound advice, it's here. I now know what I'm looking for so looking good.

Been to Steve Webb and he suggests the following:
Motor: http://www.logicrc.com/default.aspx?ItemId=M-FS3535/05&s=
ESC: http://www.servoshop.co.uk/index.php?pid=TPWH40AESC&area=ESC

Both very reasonably priced (in my affordable range).

Thanks again

CC

Hmmm...

Well in my view that motor will be too small and too "hot". I'd be looking more at something like the KD A36-12L on 3 cells and a 11-7 or 12-6 prop, or  perhaps the XYH 35-42/1250 on 3 cells and a 10-7 or 11-6 prop.

Both of these would be too big for that speed controller, so I'd be looking at a Turnigy Plush 60A controller (from hobbyking).

PDR

Yikes, Hobbyking -  what a horribly annoying website! Someone rabbitting on about something I'm not interested in which I can't turn of and all the prices in $ which won't reset to £ even when asked !

OK, checking at GC I find: http://www.giantcod.co.uk/speed-controller-opto-p-402445.html
and motor  http://www.giantcod.co.uk/xyh3542-1250kv-brushless-outrunner-p-403280.html

both of which are cheap but I hope not nasty!!

If you have an OPTO speed controller then you'll need a seperate power supply for the receiver and servos. I'd look at the Turnigy Plush range at hobbyking...

PDR

Thanks PDR but I can't make their website talk sense. Are they in the UK or USA? Looks like the latter as it's all in dollars.

They are in Hong Kong. What I'd suggest is one of THESE plus the corresponding PROGRAMMING CARD

You can get the same stuff in the UK under the "Hobbywing Pentium" brand, but it's rather expensive over here.

PDR

http://www.giantcod.co.uk/black-mantis-60amp-speedcontroller-p-402907.html

This is a great speed controller. I have two of them and programming useing your TX is a sinch.  No worries about separate power supply for the RX. I know it's a bit more but it is a good ESC.

I still don't know what weight your model is so can't say what motor I would go for.

It's a 48" built-up Spit - roughly the same size as the Balsacraft/Ripmax one and probably a similar weight (various past build threads show that they come out between 3.5 and 5lbs depending on which batteries, finishing techniques and whether retracts are used). So 400-500watts should be more than ample.

Chedder - it's worth reading the whole thread on RCG before you start - there are some errors on the plan and the original designer (Dave Philpotts) joins in about twenty pages in. One of the errors is that the marked CG is too far back, which is definitely worth knowing...

PDR

Yes that's a very useful thread and I'll keep it available during build. I have finally ended up with the following:

Controller:  http://hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=2166&Product_Name=TURNIGY_Plush_60amp_Speed_Controller

Motor:  http://www.giantcod.co.uk/xyh3542-1250kv-brushless-outrunner-p-403280.html

All servos are HITEC HS82MG

Retracts :  http://www.servoshop.co.uk/index.php?pid=EFLG200&area=RET

Almost finished cutting out all the "bits" so almost ready to start "The build"!

Crikey, that was quick! Servos, retracts and motor here already! Rugby not going so well though

Thinking about the build to come, is "super glue" the best building glue or should one use epoxy in places and even balsa cement?

Planking of sheeting? I feel it is very difficult to do compound shapes with sheets so would lean towards chamford planking in those areas. Suggestions would be appreciated.
Cheers. CC

When I'm building with Balsa I use aliphatic glue or wood glue. Sometimes I will use epoxy but not normally on the actual build. More for the smaller components. Aliphatic and wood glue soak into the wood and make for a stronger bond. On smaller models like guillows ones I'll use CA.

Hope this helps.

If you do plank parts of the fuselage this can call for careful choice of glues to ensure that the glue joints sand nicely. Slightly thinned aliphatic or good old-fashioned balsa cement are my usual preferences for planking.

PDR

MF-TB-04 Titebond 'Original' Aliphatic Wood Glue - that's the one I've gone for so should be OK.

Right, fuselage build. In the above thread one person just seems to start in the middle and work towards the front and rear from there whereas another makes a jig with pegs at the former locations. The latter looks to be the best option but I couldn't find an exact plan on such a jig. Anybody tell me where I can find one please, with dims etc?

Nearly finished the paste/cut/sand of all the ply and balsa parts so picture coming shortly. Not easy to post from my Apple Mac Air as iPhoto doesn't have a re sizing option in it's edit. I can only resize when I export the picture and one has no idea what size they are!

Phew!. Just about all the cutting, sanding done, although I still have to modify the wing formers to take the servos and retracts, and a fuselage jig made to suit (with a few of the formers clipped on to see how they look). Hope it works!
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Well it's a week since your last post here... Is there any progress? It's all looking good so far.

Arrrrrrr! I'll try again - files too big so you have to go back and you've lost all the post!! Very frustrating!!

 :afHi there, I am building a BT Hurricane and have had some feed back regarding just about everything. A forum member (lithoplate) has built what you are attempting, perhaps you should try to contact him as theres nothing like having the T shirt.Cheers Rob.

At about the time you were typing that Manaconda I was uploading pix to the laptop for update here! All formers and ribs cut out, just a bit of trimming here and there, and the front end just about built. All formers in place so probably looking at starting a bit of planking shortly. Servos, motor, ESC and landing gear received but still to be tested. I've moved the fuselage servo mounting position as far forward as I can to help CofG later on. Ummm still not quite sorted this picture adding thing!
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Wow very clean. looks like a nice build so far. I like your jig too. There is another fellow somewhere building a TN 62" Spit and he's using lego as a jig. I thought that was pretty smart. How long did it take to throw that up? Keep up the good work. Before you know it you'll be done Then it open sky's and rattled nerves. 

No really keep em coming.

Going back to the jig, for future builders, on the plan, the lowest part of the fuselage is where F6 meets the wing location. From here to the marked centre line is exactly 9cm. I therefore used F6 as my datum and measured the location of the other formers relevant to this former. Draw straight line down the centre of the building board and mark the 10 former locations, and the fin trailing edge, down this line. Cut 9cm long pegs and glue them down the C/L in the marked positions making sure you know whether it is the front or back of the former. I located the back of F1, the front of F2, F3, F4, and F5 and then the back of the rest, F7, F8 and F9 and the front of the fin vertical pillar.

Just had a thought that I have moved the servos too far forward and I wont get the arm travel needed? Must check later!

Just tested all the electronics for the motor and all is well (Good delivery from Giant Cod and Hobby King from Hong Kong!)

With the set up I've got, the XYH35-42 1250kv 45A Brushless Outrunner etc, how do I calculate the right propeller for the job? There's nothing on the plans to suggest a starting point so a bit of help would be appreciated. The shaft is 4mm dia but obviously there is a hub assembly to go on there.

Are wooden props a good idea (look nicer!) or should one stick to composite? Two or three blades (the Mk9 had a 3 bladed prop in real life I believe!)

A bit of progress today. I've constructed the rear section, from F9 to the fin vertical strut, comprising the tailplane mount and fin. Plenty of sanding to do there as all parts are just lumps of balsa! I've also tested the retracts and they both work fine. First pic shows the build up at the front of the fin, all to be sanded to make nice tapered leading edge from fuselage to fin leading edge. Oh the purple thing is a set-square keeping the fin vertical! Ah-ha! Got the pictures right this time!