Modifying the Top Flite Spitfire I accidentaly bought on ebay.

[Jon H]

As some of you will know i accidentally bought a Spitfire on ebay. 

 

The full backstory is on the ebay sellers thread, but the long story short is i saw this thing for sale at a low price, noted the wing joiner brace had been left out during construction, and was then peer pressured by all the guys on the thread into placing a silly bid over my original limit that actually won the day. 

 

After collection I promptly cracked the wing in half and put it all to one side while considering my options. 

 

This consideration is important as i have too many Spitfires. I know, its almost impossible to have too many Spitfires, but i have an unfinished 80 inch (5.4 scale) DB MkI, an unstarted  5th scale 88 inch Fokkerc MkXVI, and 88 inch Yellow aircraft MkXIV as well as this almost 5th scale 86.5 inch MkIX. 

 

One of the 4 has to go, i simply do not have room to store them as they are let alone when they are finished. The FRC and Yellow are both safe as the XVI is the best looking of all Spits in my opinion and the Yellow belonged to a friend i used to fly with and i know how good it is. 

 

This means its between the TF and the DB. Looking into the issue, i discovered some scale issues with the TF. Something didnt look right about it in plan, and some investigation later revealed TF have moved the wing back from the scale position, probably in an effort to aid c/g. The tail is also a fraction oversize at exactly a 5th on a 5.08 scale model. I think i can live with it though. The wing...nope. I measured it several times from my 3 other Spitfires accounting for scale factor and all that. The other 3 are all almost identical, this is different and its not right. 

 

 

I also found the wing dihedral is too low giving a slightly squashed look, and it lacks the scale flat centre section of the full size. 

 

 

This i cant live with either. 

 

The nose and cowl also need to be reworked for a more scale appearance, and the canopy swapped for a taller one as the TF canopy is a bit squat. 

 

I want a MkI Spit powered by one of the new Laser 200 inline engines. I would ideally like it the same scale as the others i have at exactly 5th scale but the TF is close enough. However to make it into what i want i need to build a new wing centre section, graft the original outer panels onto it, move the wings forward about 50mm along with all the wing fairing, and make a new cowl, flaps and other scale details as well as glass and paint. The core airframe is well built so it will be worth it, and its less work than a whole model build, but its a big job. 

 

To be clear, i could sling it together as is and only scale nerds like me would even notice it was wrong. But like a dead pixel on a pc screen, i cant unsee it now. Also the covering is a bit sad in places with scrapes and holes in it so it needs stripping anyway.

 

The big question then. Do i  sell this, keep the DB MkI and live with it being small? turn this TF MkIX into a MkI with all the mods and flog off the DB? or sell both and buy a 5th scale Fokkerc Spitfire IX without a cowl and turn that into a MkI? 

 

Part of me is really interested in the modding challenge, but what do you guys think? Would a kit bash thread be more interesting viewing? 

 

 

[Chris Walby]

IMHO, sell the TF. Its never going to be 100% right to your eye + you will spend a disproportional amount of time getting it close where you could better spend your time on something else.

 

Any thread be it modification or kit bashing is welcomed in my book.

 

I don't have an ic size Spitfire and it would save me ordering the P51 + it can't fly any worse that the SG Hurri can it?

[kevin b]

With all due respect john, I don't think any artf Spitfire would meet your requirements (not that I am calling you fussy).

So sell both of them and build one from plans.

Modifying either would probably take you the same amount of time as the build and you would be refinishing anyway.

I'm sure Kevin would be more than pleased to run the build in the magazine over a few months (just think of the free publicity).

[Paul De Tourtoulon]

Come on Jon, build yourself a Laser Vee twin and dazzle all at the air field, I am sure that they wont notice the 'unscale' bits,

 

you can't have enough Spitfires, throw something else away,,,

[Jon H]

I am not looking for exact scale perfection. Watching Dave's thread on his Yellow Spitfire my efforts will be decidedly lacklustre even if i nail it. I am not looking for competition scale, but better than wonkey wing scale. None of my current warbird fleet are true scale, but they are close enough that you cant tell at a glance. This is all i am after. 

 

You are all right of course. Trying to make a silk purse out of a sows ear is not always a great plan, but then again my ugly mustang turned out all right (assuming it will actually fly) and i really enjoyed the process. My main issue is cost as modifying this would be significantly cheaper than building new as i only need to buy a canopy, spinner...and that's it. I have wood in stock for mods but not for a full build, the time invested would be less than a full build. £55 has me my upgrade parts (offset by the £50 spinner from the kit put into stock for another model) and then it just a matter of doing the work. 

 

Still, i am not in a desperate rush as nothing will happen in the short term as i have other projects on the go and, unfortunately, my mum is ill again with the big c. Musing about Spitfires is a nice distraction. 

 

Chris - Nothing could be worse than the SG Hurricane. I am still so annoyed about that. My DB example is on rails and so easy to land. SG made such a mess of that model. If i ever see one cheap i will snag it and see if i can fix it. Most likely it will need new wings as its pretty hard to mess up a fuselage. Its just a stick to keep the engine, wings and tail apart. As long as its straight you cant go wrong! 

[Nick Somerville]

Personally I would find the task of reworking a ‘duff’ model disheartening. Building from plans gives you  complete ownership of the build with the ability to add as much or little scale detail as you wish. That said, the cost of putting together a 50cc ish sized warbird from scratch is eye watering and far greater than going down the artf route.  If you rate the DB Hurricane so much then why not crack on with the DB Spitfire?
Sorry to hear about your Mum, Jon. 

[Jon H]

1 hour ago, Nick Somerville said:

 If you rate the DB Hurricane so much then why not crack on with the DB Spitfire?

 

I kinda want a bigger one. The 5th scale 88 inch span is really nice and as i said before, i sort of have this foolish fantasy of having a 5th scale example of an early merlin, late merlin, and griffon spit. I need far more storage space before i can put this daft plan into motion. I am also working on the basis that i have had the DB Spit sat there for nearly 15 years and not touched it. If i was that excited by it, i would probably have moved it to the front of the line. It is a great model and they fly very well, i would just like something a little bigger.

 

1 hour ago, Nick Somerville said:

Personally I would find the task of reworking a ‘duff’ model disheartening

 

I find restoring some old shed of a thing to working condition to be very rewarding. That utterly trashed OS 40fs i rebuilt, the ugly mustang, an upcoming flair pup... I enjoy taking 'junk' and making it functional. The TF Spit is far from junk too. The core of the model is really nice and its well built so i would be left with a decent model in the end. Moving the wing should not be that difficult, canopy and spinner are easy, and the wing centre section is what, 5 ribs? I would also need to modify any model i buy to suit the 200 inline anyway. 

 

One thing i do plan to do is mock up the model with the wing/engine in the place they would end up and check c/g and final flying weight. They would be ballpark figures, but would be a guide to work out if it will end up too heavy as i cannot really do much to make the tail lighter. 

 

 

 

On the cost, i think these were about £900 quid new! For that money, i would absolutely build one from FRC or wherever. I am only considering the kitbash plan as its a cheaper way to get what i want. 

Edited December 7, 2022 by Jon - Laser Engines

[Paul De Tourtoulon]

I also have the SG Hurricane it is fun to fly but it only looks good far away in the air with it's distinctive OS .80 four stroke 'sound system',

the colours OMG,, so throw that one away.

[Jon H]

37 minutes ago, Paul De Tourtoulon said:

I also have the SG Hurricane it is fun to fly but it only looks good far away in the air with it's distinctive OS .80 four stroke 'sound system',

the colours OMG,, so throw that one away.

 

It was the 80 inch SG Hurricane that gave trouble. Not tried the small one 🙂 

[Paul De Tourtoulon]

There is a 80" 33cc one in our club, repaired a couple of times and still hasn't had a proper flight,,,

 

 good luck with yours,,,

[Gary Clark 1]

Hi Jon,

 

I have to agree with the other guys and say the TF one isn't really going to cut the mustard. I have been repairing mistakes in my own Spit build (all my own mistakes I'll add) and that almost got me to the stage of starting again. To get it to a good scale standard then you'd probably have to build a completely new wing, cannibalise the fuselage to move the formers to fix that and you'd almost have built a new model by that stage.
 

I like to buy an ARTF "scale" every now and again to practice flying techniques and bash the circuit all to save my proper scale builds. This is the perfect use for them but the incorrect scale details is painful sometimes.  I have a Seagull P-47 for exactly this reason so I'm ready for my Brian Taylor P-47 when I finish it

 

If it is not for bashing around the sky, I would move it on. There will be plenty of people interested I'm sure. I'm one of them! haha

 

Gary

[Jon H]

I have been tinkering away and have done my c/g test. 

 

With the airframe assembled and supplied steel plates removed it weighs about 9lbs. Not bad. Strapping a laser 200i in its approximate final position velcro and holding the model up on its revised c/g (ie with the wing moved) i need around 6lbs of weight in the cowl  if installed half way along the engine. With the weight of the engine i end up at around 20lbs rtf. 

 

Thats not too bad and i can save some weight in the tail. Moving the wing forward would also bring weight with it and i am missing the spinner, radio and batteries up front. All in all, weight distribution is not a show stopper for the project and i think i can whittle ballast down to 2lbs with an AUW of 20-21lbs. 

 

As for the rest..

 

The work is no bother, really i am not at all worried about that. Building a new model would be more work so that aspect is not a real concern i suppose. As i mentioned before, cost is my primary concern as this currently owes me about £230 i guess if i include the fuel to go get it. It is a lot of model for that money and i could not buy another model (like FRC) for the same money and have it at the same level of completeness. I mean the FRC is going to be about £250 and that is just the laser cut parts and a canopy. I could sell this for more than i paid, but if i sell it to one of you chaps for example it wouldnt be right to mug you off for £400 or something to cover the cost of the new FRC Spit. Even if i ebay it again and someone bids £400, it still seems a bit of a con to me and i am not a fan of that. 

 

In any case, if i go ahead with the mods i am not trying to make it perfect. Just a little better than it is. I still need to investigate the structure and how i would do the mods with a minimum of work. I dont want to start hacking and then hit a snag as i cant sell a half chopped wreck. i need to be sure it is all going to work before i change anything. Its all to play for at this point

 

 

Edited December 7, 2022 by Jon - Laser Engines

[john stones 1 - Moderator]

Can't see a problem myself, your project and you addressed the + n - involved, get your workbenched cleared. 😉

[Andy Gates]

12 hours ago, Jon - Laser Engines said:

With the airframe assembled and supplied steel plates removed it weighs about 9lbs. Not bad. Strapping a laser 200i in its approximate final position velcro and holding the model up on its revised c/g (ie with the wing moved) i need around 6lbs of weight in the cowl  if installed half way along the engine. With the weight of the engine i end up at around 20lbs rtf. 

 

I really hope you don't take this the wrong way Jon and I don't think you will, but you are talking of adding weight to a machine to acquire the correct CoG which is obviously the correct thing to do. The sort of weight you are adding are the weights my (electric) machines fly at which seems alien to me! Even my 80+" flying boat does not quite get to 6lb rtf.

 

Best of luck with the mods but it does sound like an awful lot of work.

[Chris Walby]

So if the wing is left in its current position how much lead do you need to get the C of G?

 

Plus is it worth not loading the engine mounts and making a frame so that the lead can be mounted just behind the spinner? Less lead and AUW + somewhere to put the batteries etc?

 

PS I am surprised with the engine and lead you need that much....perhaps tail lighting is required, but that's more work.  

[Jon H]

19 minutes ago, Andy Gates said:

The sort of weight you are adding are the weights my (electric) machines fly at which seems alien to me!

 

Yea it can come as a shock if you arent used to warbirds. I fly a number of WWII fighters and adding a few lbs of lead is neither uncommon or a big issue. They are all 80-90 inch and 20-24lbs. I tend to work on 10%. If the model is 20lbs, 2 or less should be ballast. Over 10% it starts to get a little more uncomfortable but at the end of the day the blasted thing has to fly so just add what needs to be added. If its not too heavy for its span/powerplant it really is not important.  

 

I do not have exact numbers for the relevant marks, but the dry weight of a Spit V was 5065lbs and the weight of the engine was around 15-1600lbs. So almost 1/3 the dry weight of the aircraft was the engine. If we assume a 20lb model Spitfire, it would need an engine of around 6-6.6lbs to get the c/g right assuming the structure of the model was as light as the full size once you scale it. My engine is just over 4lbs, and pretty heavy as model engines go but i am still too light so i need some other ballast both to get to my scale engine weight and cover off the heavier than scale airframe. 

 

I did make an error in my calculations yesterday and mounted the engine about 15mm to far back so this will clearly help with balance down the line. It may just offset the weight of things not yet added to the tail but generally i am increasing in confidence that the job can be done should i decide to give it a shot. 

[Jon H]

4 minutes ago, Chris Walby said:

So if the wing is left in its current position how much lead do you need to get the C of G?

 

Plus is it worth not loading the engine mounts and making a frame so that the lead can be mounted just behind the spinner? Less lead and AUW + somewhere to put the batteries etc?

 

PS I am surprised with the engine and lead you need that much....perhaps tail lighting is required, but that's more work.  

 

The 6lbs figure includes all the radio, batteries etc so i can easily see 2 of that dis appearing in that stuff. The spinner and prop right at the front will also knock this figure back as well. 

 

Still, the rear fuselage is very strongly built and quite heavy. Also our old mate Brunel was responsible for the design of the tailwheel bracket

 

 

Weight can be saved down the back end just by changing this. 

[Andy Gates]

It is not that I am not used to Warbirds Jon just that I am used to operating at the opposite end of the weigh scale to yourself.

 

In my fleet I have had 60"? Spitfire (now deceased), but still fly 78" Mosquito, 78" Beaufighter and all are sub 6lb in flying order.

 

I shall watch with baited breath.....

[RottenRow]

15 hours ago, Jon - Laser Engines said:

Moving the wing forward would also bring weight with it

 

Jon, please could you explain this a little more?

Perhaps I am misinterpreting your meaning, but as the C of G is at a certain proportion of the wing chord, won’t moving the wing forward effectively shorten the nose, lengthen the rear fuselage and necessitate even more weight adding to the nose?

Or am I missing something here?

Brian.

[Paul De Tourtoulon]

1 hour ago, RottenRow said:

 

Jon, please could you explain this a little more?

Perhaps I am misinterpreting your meaning, but as the C of G is at a certain proportion of the wing chord, won’t moving the wing forward effectively shorten the nose, lengthen the rear fuselage and necessitate even more weight adding to the nose?

Or am I missing something here?

Brian.

No I think the C of G is on the fuselage not on the wing,,,😅

[Jon H]

What i meant was the wing is currently in the place the kit intends and the kit calls for the c/g to be at 147mm (150 to me and about 27% chord) from the leading edge. I plan to move the wing forward 50mm, so i marked 100mm on the wing and am balancing it there to simulate the same position on the chord once i move the wing. As a result i have the weight of 50mm of wing chord structure behind the c/g that will actually be in front of it when the wing moves to meet the c/g i am using. 

 

All of this is to determine a ballpark figure for weight needed in the nose for c/g. This works out to approx 10lbs and is measured at a point that averages the position of all the gubbins i need to install (engine, radio etc) by using a spring balance to pull the model level. The recorded figure is the weight needed to achieve the same job. From that figure of 10lbs i can then subtract 4.5 for an engine, 2 for radio and batteries, 1 for a spinner and prop and that leaves me 2.5lbs of lead ballast. With an airframe weight of 9lbs, i add my 10 to get 19, then add another 2 for stuff i have forgotten and i get 21. 21lbs for a 86'' WWII fighter is fine, and i can save a little with a lighter tail wheel, moving the wing forward saves a bit as described, and i short changed myself and mounted the engine too far back when measuring so i can gain a bit there too. 

 

This method is not 100% accurate but it works well for determining if the plan is at least halfway possible and i would say looking at the numbers its actually not bad at all.  

 

I did scale the c/g positions of DB, FRC, Yellow and a BT Spitfires and they all gave quite close results about 12-18mm further forward than the TF recommendation. However, my DB Hurricane was balanced at the plan position and was mega nose heavy, i also found reports of Yellow Spits balancing further back to prevent nose overs. As i tend to fly with very low rates i think its going to be ok even if i am towards the rear of the c/g range. 

[Jon H]

Just now, Paul De Tourtoulon said:

No I think the C of G is on the fuselage not on the wing,,,😅

 

The c/g is all about the mass distribution but it only matters when you relate it to the centre of lift on the wing. By moving the wing forward the centre of lift will move forward and take the balance point with it. The moment to the tail will increase though making the model more tail heavy than it would have been without moving the wing. hence the need for more ballast and all my c/g experiments. 

 

Incidentally the longer tail moment should make the tail more effective and the model less sensitive to a tail heavy condition. 

[RottenRow]

Thanks for the explanations Jon, perfectly clear now.

 

Brian.

[Flying Squirrel]

No technical opinion here but I do love seeing people making a model their own, following the ugly mustang thread was an eye opener for me in such as previously I'd be scared stiff to attempt any mods, now I'm quite happy chopping and carving to make things fit!

[kc]

Well done to Jon for getting this model back to decent order and keeping an unsafe ( wing spar missing ) model away from the public.   I think Jon deserves any profit he gets - it is skilled work and he took the risk of buying a possibly incomplete ARTF.   Sell it to a competant pilot though!.   The idea of just any wealthy but untrained member of the public getting hold of an ARTF 28lb model with large engine up front is worrying.