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The Cost Of Building: Recording The Financial Cost of Building a DB Sport & Scale Skyrider. A Surprise for Miss Blue Eyes.


David Davis
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In another thread a contributor commented that the price of a Black Horse ARTF Speed Air was now £263 and that it would cost him £150-£200 to build something similar. My initial reaction was to say to myself, "I reckon I could knock up something similar for £50!" but then I surprised myself when I looked into matters a little more closely.

 

On 12th January 2019 two pairs of blue eyes met over a crowded library floor and two lives have never been the same since; we even built a Super 60 together. She wanted to finish it in purple and pink but I persuaded her to go for a more "boring" blue and white scheme. Last year I bought a DB Sport & Scale "Skyrider" short kit as a follow-on model for her. I plan to build it over the next couple of months and present her with it finished as requested in purple and pink!  It'll be easy for me to keep it a secret because for the time being at least, I live in France and she lives in Somerset. The short-kit cost me £53.40 including postage and VAT and the purple and pink film cost me £37 from Steve Webb Models delivered to a UK address. The Skyrider is about the same size as the Speed Air but it has a shoulder wing rather than a low wing.

 

I was once told by an old boy that all modellers were hoarders and it's true that I have sufficient material to both build and cover the model, it's just that I do not have any pink or purple film! I will monitor the cost of replacing any materials I use and report back.

 

So far the project has cost me £90.40 so the other contributor's estimate of £150 doesn't look too far away.

I'll bet that you look good on the dancefloor.JPG

Edited by David Davis
Grammar
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Good photo ‘DD’ and that’s great you have started this thread up after the other comments on the Laser thread. Shall follow with interest to see how the costs stack up.  It’s always a surprise how much gets spent on those small sundry items and as you say most long time modellers usually has a good supply of these, but they had to be bought at some time, or at least recycled.

 

I hope the maiden of the pink and purple subject takes place in cider country and if it does I will drop in for it, as it is where I live too.

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I am flying a travel air after graduating my 'A' with a trusty boomerang. The new cost was just obsurd for me when there is a strong likelihood of it coming to harm as the boomerang had a bit of a hard life shall we say. Perhaps in a few years I would look to buy a new new model as I will hopfully have confidence in my abilities but whilst still learning the new cost on same basic planes is crazy for me just starting out. I got my travel air for £30 off ebay delivered, few covering patches and a second hand engine irvine I had laying around and she flies quite nice.

 

It will be interesting to see the outcome of this, what could be handy is if you log your build hours as well?

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13 minutes ago, Graeme White said:

...It will be interesting to see the outcome of this, what could be handy is if you log your build hours as well?

Good idea Graham.

 

I will convert the Skyrider to electric power. I don't think that she's into dirty i/c engines. That said she was brave enough to be my mechanic in the 2019 Coupe Des Barons.

 

 

Trish and me at the starting boxes..jpg

Trish me and Bertie.jpg

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I'm a bit OCD about recording airframe details on projects, so just to break that number down DD, my current build (bit bigger, 60 size, twin) has set me back:

 

£20 in assorted P&P costs

£60 for wood for the wings

£55 for wood for two fuselages and tail end (it's a twin boom effort)

£40 for misc hardware - U/C and control rods and so forth.

£30 for covering film and canopies and a bottle of plastikote varnish for fuelproofing

£30 for the radio - I recycled the big ticket items from retired airframes, but, new switche, battery, fancy extension leads and some fresh horns were needed.

£250 for 2 x old OS40FS from ebay, inc new bearings, tanks, filters, mounts and spinners, and I was pretty pleased at the price I got this lot for

 

I'm sure I've missed a few small bits. Some cyano, a packet of screws, etc. Another £10 or £20, easy. I already had some solartrim.

 

If I'd gone electric, 4max prices for a couple of 40A speed controllers and 3541 motors would be around £150.

 

The wood, hardware, covering totaled £205. That is with current wood prices. Two years ago it might have cost about £50 less. To get a 40 size figure, I just fudged it by 75%.

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PS Same twin has 140 hours on the build so far, which has split three ways almost equally between wing, fuselages and covering/finishing/assembly. I have only a bit of final assembly and finishing jobs left, maybe five or six hours of fettlng.

 

One way to look at it, the £500 (ish) total isn't bad for 150 hours of hobby time.

 

Hope that provides some useful numbers for anyone to compare and contrast with.

Edited by Nigel R
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  • 1 month later...

I started work on the Skyrider today.

 

What you get for your £53.40 in a little cardboard box is a set of laser cut wing ribs, a dural u/c, a set of profiles for the formers and a plan which is not shown in the picture. The profiles are printed onto paper which has adhesive on the other side, so you cut them all out, stick them to the balsa and cut round them.

 

The fuselage is thirty-six inches long and nearly five inches wide. I didn't have any sheet wider than four inches so I was forced to cut a little more from a third sheet and to glue it edge to edge. I'll leave it to dry overnight.

 

Cost of balsa so far: £10.44.

DSC02001.JPG

DSC02002.JPG

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I used to build/assemble my own pedal cycles - singles, tandems and trikes.  I usually built my own wheels too. What I never did was count the cost because it was something I wanted to do.  Now, similarly to model aircraft, the range of 'ready to ride' pedal cycles is vast - there's something to suit everyone but back in the 1970s if you wanted a decent bike you had a frame built and either paid the supplier to assemble it or did it yourself.  My 'racing bike' was an old Mercian frame, stripped down with a pair of sprint wheels I built.  I wasn't very fast but I sometimes wonder how much quicker I'd have been with a modern time trial bike costing many, many times what my old s/h Mercian did.  ?

 

I take the same attitude when building models.  If I can afford it I buy the necessary wood/electronics/ power source etc as and when I need them but I never work out the totals and never will.  However, I'm glad someone else is taking the trouble and I'll watch with interest.

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In my first post of May 20th, I expressed surprise at the alleged cost of building a simple sports model being £150-£200. Indeed I said, "I reckon I could knock up something similar for £50!" I don't think that I will have spend much on the Skyrider simply because I already have stocks of most of the materials. I've had to pay £37 for the purple and pink covering material because that's the colour scheme she wanted but I could have saved that if I'd used film from existing stocks.

 

I am keeping an account of expenditure to see whether £263 is a fair price for a Speed Air. So far this model has cost me over £100 and that includes the cost of replacing the wood.

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One of the ways of keeping cost down is of course to use the balsa in the most economic way.   When the fuselage sides need more width than the 3 or 4 inch sheet then cutting off the offcut from the tail end first usually provides the extra bit to glue on the front.   Utilising the machine cut edges makes the joint easy and you can be sure it is exactly the same thickness ( not always the case - sheets vary.)  Might save using another full sheet.

 

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of course it all depend on what you get with the Speedair. Some ARTFs intended for glow power are just a bare airframe and you need all the radio gear (inc servos etc) as well as an engine and possibly a fuel tank and tubing.  Whereas electric foamies like (say) a Riot include everything except the radio receiver - mine was about £120 IIRC.  The last ARTF I bought is a wooden Wot4 which came with nothing but the airframe and cost £110 plus p&p.  I had to fit a motor (which I already had) and servos.  I guess the cost 'in the air' was getting on for £250 if I'd had to buy the motor and esc.

 

The Das Liddle Stik I built from a free plan back in 2020 probably didn't cost all that much but again I used a lot of stuff from stock so it's difficult to judge.  It's only about 1 metre ws and I used covering I had in stock (that would be expensive now that HK film seems not to be easily available).

 

 

 

                                                                               1533334501_complete7.thumb.JPG.ba133ef94c5af31a6b902d168ba55948.JPG

 

 

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The fuselage sides are complete. I reckon it's taken me about two hours to get to this stage.

 

According to the build notes which came with the short-kit, the prototype weighed 5lbs but weights of up to 6lbs are acceptable. If it were my model I would fit a two stroke glow but as it's intended for Trish I will fit an electric motor. Electric flight is not my thing but I have two electric motors sculling about: a Pro-Tronik DM 2830 and an Axi 2820/10. Specs here: https://www.absolu-modelisme.com/moteur-dm2830-kv660.html and here: https://www.modelmotors.cz/product/detail/221/ I will probably go for the Pro-Tronik.

 

I have a number of LiPos which would fit in the aircraft ranging from 2200 3S LiPos to 4400 3S Lipos. The 2200s will fit without modification but will they provide sufficient flight time if I were to prop the motor to provide 100 Watts per lb? If I need to fit a bigger battery I will mount it diagonally in a tray as per Chris Foss's modification for the WOT 4. This will involve cutting a hole in the F2 former to accomodate the tray. What is the view of the electric bretheren?

 

Another modification I intend to make is to make the F2 former out of 6mm ply and to extend the height of the former by 5mm to allow me to fit a dowel to the wing's leading edge and to use plastic bolts in captive nuts at the trailing edge rather than use elastic bands.

 

 

Fuselage sides complete.JPG

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HI DD,

 

I have a full subscription to e-calc, so did a few 'what-ifs' for you.

 

Using the Protroniks motor, you'll need a pretty big prop. A 14x8 will give you a thrust to weight ratio of around 0.9, which will fly it nicely, and a flight time of around 5 minutes on the 2200 packs. A 16x8 will give you a thrust/ weight ratio of 1.1, or 'plenty'! That will reduce your flight times to 4 minutes. That equates to 468W of electrical power.

 

Bigger packs will help, and will also help the CofG too.

 

Let me know what you plan using and what props you have and I'll run the simulations for you.

 

Graham

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Thank you for the information Graham, very interesting.

 

I think I'll go for the smaller prop and the largest battery. If I could get five minutes out of a 2200 mAh LiPo, I should be able to get ten minutes from a 4400 mAh LiPo. So that decides it, a plywood F2 former with a hole in the bottom to allow for the LiPo!

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On 25/06/2022 at 08:12, David Davis said:

Axi 2820/10

 

£75 right there... Don't forget suitable prop, speed controller, spinner, mounting bolts/T-nuts/studding.

 

Also, a pack of nylon bolts, some dowel for wing location...

 

It's always the small stuff that gets the total cost up.

 

If you had it already, that only makes cost building it less for you - versus the cost of building it full stop, as it were. Not sure which one you're trying to record in this log?

Edited by Nigel R
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2 hours ago, Nigel R said:

 

...If you had it already, that only makes cost building it less for you - versus the cost of building it full stop, as it were. Not sure which one you're trying to record in this log?

I suppose that I could keep an account of both options.

 

When I thought, " I could build this for £50!" I was naturally thinking that I have considerable stocks of wood, glue, and covering material. The radio, motor and wheels were also in stock.

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I have to agree that you need to put a reasonable price on everything, so wood, covering, hardware etc, otherwise its a bit disingenuous, many people don't have any stocks of wood or hardware. My estimate for a similarly sized model would be:

Wood = £120

Covering = £30

Undercarriage = £10

Linkages, hinges etc = £30

Glue = £10

 

So maybe £200 for the airframe alone, plus probably the same in motor, radio gear etc. 

 

 

 

 

 

 

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