Nijhuis Hurricane in foam

[Toni Reynaud]

Undercarriage.

In the Bits Box I found a pair of wheels the right size - 80mm, about 30mm thick. However, playing with the retract system, even with the recommended 6kg servo there appeared to be a bit of strain. Lighter wheels were in order, so with an article from an old magazine in mind, I cut out some 5mm balsa centres and 80mm tyre sections from an old camping sleeping mat. I used a piece of aerial tube for a axle bush and when assembled I had a reasonable facsimile of a wheel. I will have to shape the tyres and paint them ( blue and pink striped tyres are definitely not scale!), but the original wheels are 60 gm and the homemade ones are 6 gm! No contest!

 

All the bits - original wheel, centre, tyre, single thickness assembly ( the final wheel is three thicknesses) and axle bush..

[Toni Reynaud]

The motor and ESC turned up, and I made a plywood box 60mm cube to mount it the motor on. I fitted it to the firewall in the position indicated by the plan, hollowed out the inside of the cowling to get clearance, and found I'd fitted it 2mm to one side and 8mm low!  I created a new set of mounting holes, refitted the box, and was 2 mm high! At this point I lost patience. I cut off the 75mm nose ring and replaced it with a 75 mm nose disc, and mounted the motor straight onto that. Much easier - it's in the right place immediately! I then glued the cowling onto the front of the fus with 5 minute epoxy, and all was well with the world.

Next I had to cut an access slot in the bottom of the cowling, then fiddle the ESC mounting and connection and a battery mounting system. The ESC will have to be kept cool, which inside the thick foam cowl with no radiator opening is not easy. I decided on cutting through the wing on top of the radiator to get air into the fus, then I intend to use a PC processor cooling fan to push air from the fus interior past the battery area into the cowl, and out through holes inside dummy exhaust outlets. That's work in progress - photos as and when it gets done.

[Toni Reynaud]

Just for smiles, and in between the snow showers, I put it all together with the technicolour wheels and took it out into the garden.

 

 

 I also went to B&Q to get some sample paint pots. I hope to finish it in the colours and number of the Hurri in the Malta Air Museum that I saw on holiday in November.

 

http://www.maltaaviationmuseum.com/hurricaneIIA.asp

 

[Terry Whiting]

Hi Toni,

 

How did you get on with your paint job. After the disaster of your first canopy I must say

the second is first class

What was the weight penalty in using brown paper?

 

TW  

[Phil Claridge]

nice one toni, looking forward to seeing it fly at porthole

[Stephen Grigg]

Really interesting thread Tony ,its fascinating how different people build there models with different materials,and shows the hobby is full of skillfull craftsman like yourself

[Toni Reynaud]

Back off holiday and skiing muscles well rested.

Terry, the weight penalty of using brown paper is minimal. I was interested in quantifying the intuitive side of this, so I made a few measurments as I went along.

                                        Bare                  paper glued on

 Wing                              365 gm                  443 gm              +21%

Fus                                 352gm                  392 gm               +11%

T/P, ele, fin, rudder       40gm                     67 gm                  +67% (but a very small part of the whole plane)

 

The paints are samples of matt emulsion from B&Q, but reading up about night fighter Hurricanes, I found that matt paint slowed the full size  planes down noticeably, so gloss was used. Therefore I will cover the whole with clear varnish when the (minimal) detailing is finished.

 Bought a RadioActive WWII pilot yesterday, and fitted a cockpit floor to sit him on after he gets painted. Painted the technicolour tyres matt black. It will soon be time for more photos.

Porthole? With delicate retracts in a foam wing? Not sure about that one, Phil.

 

Edited By Toni Reynaud on 07/03/2010 09:51:38

[Toni Reynaud]

I've been busy with the B&Q paints. The colour on the bottom is probably a bit more green than it should be, but the overall effect is quite nice. I still have lettering to do, which will keep me quiet for another week or so. On the other hand, it's almost fit to fly, so I might try that before spending too much time on detail!

 

 

 

Note the hangar rash on the nose already!
 

 

[Toni Reynaud]

With everything in place as in the pictures, including the two 2600 3s lipos, I weighed the Hurricane - 2.1 kg, 4lb 1 1/2 oz. This should fly nicely, I thought. Then I tried balancing it at the 90mm point - tail heavy! If I'd thought about it, I would have lightened the back end of the spine and the rear formers as I built it to get a better balance point. As it is, it needs 225gm, 8 oz of lead to make it balance where it should, a 12.5% increase in flying weight. Somewhat of an annoyance, but something else to keep me puzzling and busy for a while. Noticing the 6mm gap between nose ring and back of the spinner, I think I'll try to get the lead in that gap in the form of big lead circles. I can always pull the spinner forward a mm or two to get clearance if necessary.  Also, at some later date when it's no longer my pride and joy, I can slice the bottom of the rear fus off and chop bits of the formers and spine out then.

[Toni Reynaud]

The canopy isn't glued in place yet, but the pilot looks happy!

 

[Toni Reynaud]

Following the thoughts above, I cut out three circles of lead about 70 mm diameter, tack-soldered them together, drilled a clearance hole for the back of the prop driver, and screwed the assembly to the firewall. It weighs almost precisely 225 gm, and is an inch or so further forward than the trial weight, so all should be well.

 

Lead circles and spinner

 

Inside the spinner with prop driver showing clearances.

 

Screwed in place.
 

 

Clearance behind the spinner.

 

[Toni Reynaud]

As mentioned before, I had a few doubts about the cooling of the electronics. As planned, I have now fitted a processor cooling fan from the bits box onto the bulkhead between the wing bay and the motor bay. The wires are soldered to the pointy bits of pins which are then stuck through the insulation of the ESC battery wires and covered with heatshrink. Any time a battery is connected, the fan runs. It consumes 24 - 40 mA, insignificant in the grand scheme of current consumption. I could probably have got away with just forced air cooling in flight, but after landing the fan will still run to help stop heat buildup in the motor bay ( kills motors and ESCs! ). The air exit is four 10mm holes on each side of the plane under the exhaust stubs .

Fan in place. The black box is the Corona 2.4GHz Rx. The little box with pins on is the undercarriage slow-down gadget.

 

Fan wires connected to the battery leads.
 

 

[Toni Reynaud]

Today I got to check the power system. The motor is 1000Kv 400W, the batteries I'm using are a pair of Mystery 2800 3S LiPo, the ESC os 60A rated. The prop is 12 X 8. With the plane tethered, everything connected and the controls answering to the radio it was time to open up. It all worked smoothly, nad sounsed like it was going fast. A quick look at the Medusa Power Analyser at full throttle showed 613W at  56A - way more than I had anticipated. Half throttle gave about 250W, which would be a good cruising setting. However, bearing in mind that it's not good to overstress the moter or ESC, I changed the prop for an 11 x 7. This gave 464W at 42.5A, battery voltage about 10.5V on load. This is a lot better for the system, so that's what it will fly with to start. a 12 x 8 or 7, or perhaps 11x8 will be tried later on.

This shows the first full power run. The photo of the second is a bit fuzzy. This all shows the value of using a gadget of this type.

[Stephen Jones]

Hi  Toni,

Its been interesting watching this one take shape .By the way  i cannot see much reinforcing to keep the main wing in place , just above that fan ! . will you be flying it this weekend ?  

[Toni Reynaud]

Hi Stephen,

No, it's not been flown this weekend - I've been away in the camper. Flying models has to take second place sometimes.

The wing is attached more or less as per the plan - 6mm ply subformer at the bottom of F2 with holes in for dowels inserted in the front of the wing leading edge ( the matching holes in the foam are visible in the picture above), and a ply plate in front of F4 supported by the 6mm foam doublers and smaller 5mm balsa doublers, holding captive nuts for the M3 aluminium bolts. See the pics from 06/01/2010 14:38:30. I think it will hold OK, as the fus sits on top of the wing, whereas in the Herc, using a similar fixing method the fus hangs under the wing, and that has survived a heavy landing due to catching a wingtip in long grass and flying full pelt into the top of a hawthorn tree (10ft low pass, 11ft high tree!). The last incident did break a few bits, but the Herc is now back flying again.

[Toni Reynaud]

The weather and other commitments finally came togethet today, so I went over to Thorney Island. Wind F2 -3, n-ne. Perfect flying weather, with the sun (if there had been any!) at my back. Got it all screwed together, checked controls and motor, took a deep breath and opened up[. Tracking veered it a bit right, caught on the rudder with no problem. Tail came up very fast, almost nosed over, but caught that too, Gave it a bit more up, and off it went. Gained height in a wide circuit, put the U/C up while it was overhead, and gained more height. It cruised nicely on half throttle. From level flight at full chat I can pull a big loop. Rolls need a little down when inverted. Stall is gentle but positive - the left wing falls away and the plane noses over. With a bit more throttle it just mushes on full up. Low passes both fast and slow look good. After five minutes I lowered the U/C and did one more low circuit, then landed. It's a pussycat, lovely to fly, smooth and stable. Elevator is quite sensitive. The batteries and ESC got barely warm to the touch, so the cooling seems to work. All in all it's really nice and I'm well pleased with it. Long Live Foam!

PS 2400 mAhr went back in the batteries after thr first flight, about half capacity, so 10-minute flights are well within reach.

Four flights altogether, one very short as I had to land straight after the first circuit to get my sunglasses on!

Edited By Toni Reynaud on 09/05/2010 15:23:17

[Terry Whiting 1]

Hi Toni.

 

Congrats, makes it all worth the effort. Hope you get many more flights.

I have never been a foam lover, but just recently I made use of some blue

foam and was amazed just how good a material it is,

 

TW  

 

[Trex700e]

wow thats a nice looking plane! well done!!!

 

all you need now is a spitfire to go with it!

[Mike K 3]

I need to spend more time on this site!  What a nice looking model and happy to hear of the successful maiden.  I really like your construction method.

 

Mike

[Scubajon]

Hi, I am doing the canopies for my lancaster and cannot find a glue that dries perfectly clear. The "frames" are made from cardbord strips cut to width on a guillotine, painted and the stuck on the inside of the canopy. but when ti dries there are white marks all over the place. I have, I think, tried every glue known to mankind and cannot find one that dries clear. This requires me to paint the canopy on the outside to cover these marks. I am in my 70th year and my hands are not steady enough to paint the outside and make it look the part. I have my youngest daighter, who is very good at this painting it for me, but this should not have to done at all really. Any ideas would be most welcome. cheers j

[Erfolg]

5 star canopy glue dried clear for me.

[fly boy3]

Hi Terry, Tom Wright has a great article on working with blue foam, you can learn a lot from it. Another very interesting thread is his build of the Twin Boom from blue foam. Great flier, and cheap to build. cheers. Have a look on tube "Tom Wright's 10 ft blue foam monster" Amazing. Cheers

[Erfolg]

The techniques as used by the "Free Flight Scale" modellers, who use Blue Foam, take some beating.

[Scubajon]

Erfolg Hi, I have tried that too, in fact it was the 1st one I used. The problem is, it shows through the canopy and looks awful. I don't know why it didn't work for me. Perhaps my bottle was too old! Although I didn't think it went off within a couple of years. Will try a new one and see what happens. cheers j