TN 46" Spitfire

[Paul H]

After far too many years (at least 6) I have managed to complete and successfully fly the 46" Tony Nijhuis Spitfire with a 3s system generating 380 watts (36amps) turning an 11x7. The cowling is fibre glass from a mould over a a plug taken directly from the front of the fuselage. This gives space for the motor and the lead I needed to add to achieve the correct CG.

To be able to self launch I made a simple wheeled dolly which works fine but might need a bit of refinement.

The model is based on the Mk IX Spitfire EN398 flown by Flying Officer Ian Keltie of 402 Squadron RCAF. At that time it was registered as AE-B which was then repainted as EN398 JE-J as flown by Johnnie Johnson.

Thanks Tony for a great design that flies really well.

[torbjornp]

Hi there Paul,

Nice looking Spitfire! What did you use for covering, glassed or heatshrink film? I have one too, winterproject! Do you have a sketch of your wheeled dolly? Looks real smart😀

Torbjørn, Norway

[Paul H]

Hi Torbjorn

The finish is lightweight Esaki Jap tissue on the ailerons, rudder, elevator, tailplane and fin, medium weight tissue on the wing and lightweight glass cloth on the fuselage. The bare wood was first sealed with sanding sealer before the covering was applied with Poly C, a water based varnish. If the grain wasn't first sealed I thought the Poly C would raise the grain and make finishing more difficult. I wanted to keep the tail end as light as possible but still needed about 200gms of lead in the nose.

The dolly is a simple 10swg (3mm) wire frame with 55mm wheels on the front and 50mm wheels on the back. It is 47cm long, 27cm wide 15cm wide at the rear axle. The height at the front including the wheels is 10cm. The uprights that sit at the leading edge of the wing are 8cm in front of the wheels which are raked forward. The uprights are 9cm high. Hopefully the pictures help.

[Spitfire fan]

Hi Paul. Just found your log. I am building this model,also without undercarriage, so very interested in your dolly. Please could you advise:

What is the all up flying weight;

What motor have you use;

What capacity 3S battery have you used and roughly how long a flight time do you get ?

Many thanks,

Regards, Peter.

[Paul H]

Hi Peter

Apologies for the slow reply to your questions.

The motor is a BL2815/09 supplied by BRC Models turning an 11x7 prop. I use a 2200 lipo which gives around 5 minutes flight time with between 40% and 50% capacity left. There is plenty of power and I fly on half throttle for much of the flight. The esc is 40amp maxing at 36amps and 380 watts. Flying weight is 3lb 12ozs with about 8ozs of lead in the nose.

The cowling is fibre glass. I made a plug cut from the nose when sanding the fuselage to shape. A mould was taken from the plug and then a grp lamination laid up. The result is thin and light but plenty of room to get the lead in.

The finished model flys extremely well but the take off is a little skittish so I will make some adjustments to the dolly so the rudder has more authority. Probably by a couple of uprights to locate the fuselage near the tail.

Hope this helps

Paul

[mightypeesh]

Top job, beautiful model!

Cheers, Simon

[Spitfire fan]

Hi Paul. My turn to be sorry, I had not realised you had replied. Many thanks for the info.

I'm covering the model using Deluxe Eze-Kote in combination with light glass cloth or light tissue paper.

I am aiming for a flying weight between 3 and 3.25lbs without any lead in the nose. I have roughly balanced the model with some items taped in place and I think I can get the correct CofG position by adjusting the final position of the battery without any additional lead.

What did you cover your model with ?

I am using 3S 3200 lipo and OS3815-1000 motor and 10x7E prop giving 428Watts and I have a 60 A esc. Your numbers encourage me that I should have enough power.

I am still to pass my A test so I will be getting someone else to maiden it for me and I will be praying that it does not tip stall on release, either from hand or from a dolly, copying your design. I hope I have managed to build in the small amount of washout that TN suggested on his plan so I hope everything will go OK.

Thanks again for the reply.

Regards,

Peter.

[Paul H]

Hi Peter

The details of how I finished the Spitfire are earlier in the thread. I also sprayed grey primer which was sanded back and then the finish is Warbirds Colour supplied by Fighter Aces. The finish was airbrushed using card templates which were fixed in place with small pieces of double sided adhesive foam pad to give the slightly feathered edge between the green and grey. I would imagine Poly C and EzeKote are similar as they are both water based but I haven,t used EzeKote so can't be sure.

Your power train sounds more than adequate, I have had no suggestion of a tip stall on take off or landing. It is worth being very careful to build in the washout. I found the other build threads for the 46" span version of the Spitfire very helpful and reassuring. Particularly in relation to the weight and cg. Hope you get on well and would be good to see some pictures

Paul

[Spitfire fan]

Hi Paul. I have not had much chance to progress the build since Nov., however as will be detailed in a different post my choice of motor did not work out, so I'm now looking for a different motor, possibly the same BL2815/09 you used. Did you do a wattmeter test to confirm the output as I noticed that 380Watts is the specified output for that motor /prop combo. If you actually achieved 380W then it seems model flies well at 100W/lb which is really good to hear. I assume this means you can do all the manoeuvres you would expect of a warbird, and thats what I want and nothing more. It is always possible to get a more powerful motor and i have read before that 130W/lb is required for a warbird, but adding watts just means shorter flight times for the same battery, not a good idea.

Have you flown it many times ? Have you experienced any issues with damaged props, bend motor shafts or nose overs because of the prop digging into the ground during a belly landing ? Many thanks in advance for any comments.

Regards,Peter.

[Paul H]

Hi Peter

Both the current and watts draw I quoted are from on meter readings so seem to be pretty accurate based on flight performance. Performance whilst brisk reflects what should be expected of a warbird, barrel roles, large loops and reversals are all in scope. The aileron authority is good but not particularly powerful, I.e. no fast rolls. Elevator again is good but not skittish. I have wondered about moving the cg back a little but it is in line with what the plan and others quote.

Landing is no problem, I have fitted the 2 underwing filters the mk lX has which keep the prop clear when landing, I don,t set the break so the prop is turning when it lands. Equally no sign of nosing ever, well not yet! I haven't flown it over the winter but plan to do so more this year.

Good luck with yours and I hope this helps

Paul

[Spitfire fan]

Hi Paul. That really is very good news about the watts produced, the current drawn, and how the plane flies. I have seen the underwing filters on other build logs but I thought that because of their rearward position that they might actually create a pivot point so more likely to produce a nose over or at least bring the nose and prop closer to the ground increasing the chance of damage. Adding the air intake as well would help but of course this is just adding more weight. Did you include the air intake ?

I will buy that motor if i can find it or something to give me a similar output, so i can complete the nose build and see how the AUW estimate is looking then. After that i can decide about the under wing additions.

Thanks for your help. I will think about posting some pics sometime but i don't feel ready to yet.

Regards,

Peter.