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A Spitfire reborn

#1
Hi there, I've not been too active on the forum but do tend to keep my eye on the builds for inspiration. My hangar currently consists of a few FT planes, a couple of Chris Foss Phase 6 gliders, a Westwings Orion glider and a UMX Timber. I've recently been tidying the loft and found a Spitfire my Dad made about 30 years ago. Dad has always been into slope soaring and gliders in general. These are my first memories of the hobby and ultimately why i'm here now. Dad made loads of gliders from Vampires to Folland Gnats; and this Spitfire. The Spitfire was made from a picture of a Spit that he scaled up and made from scratch himself. Sadly it didn't really like gliding (Dad prefers gliders). Guessing the wing area isn't enough to keep it aloft. So as i kid this was hung on my ceiling until it ended up in the loft. Its looking a little sorry for itself. Dad is retiring shortly and expressed a keen interest in getting back into the hobby. And so here we are, I have decided to resurrect the Spitfire and make it fly for him. I'm planning on using modern magic such as brushless motor and a lipo power to overcome its downfalls and hopefully pull it around the skies.

This is where i am hoping to gain some help. I wouldn't know where to begin to decide on motor, battery or prop size or CoG. The wingspan is 120cm and it weighs 1.2kg without electrics. The faux spinner on the front will obviously be coming off so the weight will drop slightly before the electrics go in (2 servos, 1 for elevator and the other for ailerons). I pretty sure i can fix the broken bits and get that all working and pretty. The paint is battered but is staying that way to show its past.

Here's where its at currently:

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Many thanks in advance and happy flying :cool:
 

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BATTLEAXE

Well-known member
#2
Welcome to posting on the forums my friend. Your dad's little Spit looks like it has seen better days. It may fly but there will be some things you obviously need to address.

Most importantly, beyond its clipped wing tips and the pieces falling off would be to find the CG. Being that its a glider if you could get it to float level on a glide that would decide your CG, which would mean all the control surfaces would have to be fixed up and fixed static to even test it. The FT Spitfire has its CG just ahead of the main spar, at the highest point of the top wing chord. Yours should balance out in roughly the same area. Then all your electronics are placed in the airframe according to that balance point keeping the plane level on a balance stand, just adding more weight.

Which comes to the next point, 1.2kg's without electronics sounds a little heavy even for a 1.2m wing span. Once the electronics are in and it's balanced, it will fly, but it may need a lot of speed to overcome gravity, drag, and create sufficient lift. It looks like the airframe is made generally of wood and particle board, which can be generally heavier then the usual foam board we tend to play with. Lightening this airframe may be more of a task then you are willing to tackle.

I do understand that there is potentially a lot of sentimental value in this airframe but even for him just getting back into the hobby this might not be the best option to play with... yet. If he is partial to the Spit, FT does do a Spitfire out of foam board that would be an excellent plane to play with for now, while you work on this airframe, just to get the stick juices flowing again. In building an FT Spit it may help inspire ideas to fix this plane up as well.

Of coarse this is just one suggestion, others may have better ideas to help you with this plane, others who have way more experience with wood planes then I do. It will be a project to take on though, maybe if your dad has the skills he used 30 years ago to build it, it may be like riding a bike to fix it.

As far as the motor and battery goes it will take a significant brushless motor to have the power to get it flying at it's current weight, possibly a .15-.20 power equivalent with a 45-50 amp ESC and a 2200-3000mah 3s 45c battery. Others may have charts that take the specs of the plane, (size and weight) to help determine the size and power of the motor, prop, and ESC that are needed with more accuracy. Best to be overpowered then under powered I always say.

Anyway that's all I got for now, I am sure as more people see this thread they will chime in with their respective analysis and opinions as well. Keep up the motivation and it will potentially fly again. Good Luck
 

Jackson T

Well-known member
#4
I love Spitfires! Depending on how much power you're after, this motor could be a good fit: https://hobbyking.com/en_us/turnigy-d3542-6-1000kv-brushless-outrunner-motor.html. I haven't bought that one specifically, but I bought one of the smaller ones in that range and it performs nicely. I must agree with @BATTLEAXE, 1.2kg sounds pretty heavy. But, if your flying weight with battery and everything ends up under, say 1.8kg, and as long as the wing has a similar aspect ratio (wingspan to average chord ratio) to the real one, your wing loading should be within an acceptable range for a balsa warbird (~70 grams/dm2). It will definitely not fly like a trainer, though, so it might be worth getting the thumbs going again on an FT Spitfire like BATTLEAXE suggested. Looking forward to your progress!
 

rockyboy

Skill Collector
Mentor
#5
Love the project! As mentioned there are some challenges ahead, but I think they can be overcome.

As a template for a lot of the parts and specs, there is an E-Flite Spitfire 1.2m ARF

https://www.horizonhobby.com/spitfire-mk-xiv-12m-bnf-basic--efl8650

Flying weight on that bird is 1.515 kg - that's including servos, motor, esc, battery and receiver.

So choosing light weight components at every option will be important to get the best flying characteristics possible - for example, using a 3s1800 battery instead of the 3s2200 recommended for the ARF when you're getting ready for the first flights. Or maybe 4s batteries - depends on the motor / prop!

Staying with ailerons / throttle / elevator control (skipping the rudder) will keep the # of servos down and keep you within the capabilities of a 4 channel receiver (staying light!).

You might also be able to save some weight going with a multi-rotor ESC (those have gotten really tiny) and a stand alone voltage regulator like this one https://www.readymaderc.com/products/details/pololu-5v-2-5a-step-down-voltage-regulator-d24v25f5 Yes it's two parts and some wire rather than one part, but compared to some traditional 40amp or 60 amp ESC's I have almost cut the weight in half on some projects!

For motors the Turnigy suggestion above would work fine, but at 660 watts it could be more motor than you need - it can handle up to a 3kg plane with a 100 watts per pound ratio, which is way heavier than you should get with a 1.2m wing span. You could spend more on lighter motors that put out a little less power, mostly trading weight savings for money. The Cobra 2814 with the 3s power with an 8x6e prop puts out 345 watts - which is good power for a warbird up to the 3.5 pound or 1.6kg range. If she comes in heavier, a 4s battery with 7x6e prop puts out 460 watts and will be solid for up to a 2.1kg - but that is going to be a good bit heavier for the wing size - very much the opposite of a glider!

https://innov8tivedesigns.com/parts/brushless-motors/cobra-c-2814-12-brushless-motor-kv-1390
https://innov8tivedesigns.com/images/specs/Cobra_2814-12_Specs.htm

Does that help you get going on the planning? Fire away if you have other questions - I'm sure you can pull this off, but she will fly like a warbird - not a glider. The suggestions of getting some stick time on a FT Spitire is a good one :D
 
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