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Danny's "poor mans Spitty"


Danny Fenton
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Hi John, the c of g has come out about right with a 4S 4000 pack, so no lead was needed, and to be honest I am probably 5mm more tail heavy than the plan as for control line they are more stable that way.

The weight will be what it will be, but it must balance. it would be interesting to hear from those that have flown the DB Chippy as to how correct they reckon the indicated c of g is?

Remember mine still hasn't flown. I have however been told that Barton have a tarmac circle

Cheers

Danny

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Hi Danny, a larger battery was the perfect solution. A 5s 4300 balance's perfect.

Did my initial set up trials;5s 4300 25c

12 x 8

Weight 6lbs 4oz

1024 watts

54 amps

I reckon that's about 160 watts per pound? Enough to be flying by the seat of my pants. I might put a larger prop in t. Bring the wwattage down to fly more scale like

Nearly there, just need the roundels and lettering and then on to flying

Cheers

John

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No problem at all John, hope they suit your scheme, it was for the silver with yellow banded scheme that mine is done in, though many stencils are the same I am sure.

Any Chipmunk fans coming to Greenacres this weekend? if so it would be nice to get the models together for a piccy or two?

Cheers

Danny

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  • 4 weeks later...

Hi Tony, sorry I missed the notification of your question. No news on the maiden. I am concentrating on getting a Hurricane maidened, but the Chippy is more or less ready to. Trouble is I am struggling to find a 120 foot tarmac circle. I was hoping Barton might work but it seems to be in use pretty much all the time by the speed guys, and I will have to join the club just to queue to use it...... may have to go R/C first as finding a strip is easier.

Cheers

Danny

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While still trying to find a venue to fly the Chippy on wires i thought I would finish off the couple of tasks needed to fly the model R/C. namely bushing the Glass board hinges.

A few had commented on this as being tricky, well i thought i would just show how I did this.

firstly I made sure I had some 2.5mm OD brass tube. The ID was a nice fit for the 10BA screws.

The holes in the glass parts were opened up to 2.5mm and the tubing cut to give 1.8mm bushings. How do you cut small bushings, you may ask? put the tube gently in a vice, drill a 2.6mm hole in the glass board and slide over the tube. Hold the outer edge flush and with a jewellers saw mark the tube the exact width of the board. Remove the board and cut through. Once cut slide the bush over one of the 10BA screws and file the bushing flat. Turn the bushing and file the other side. It sound tricky but it is easier to do than explain. If you haven't a jewellers saw then you might struggle......

Drill a 2.5mm hole in a section of scrap glass board and trial fit a bshing to make sure that the fit is snug, and that the bushing needs tapping home. Once you are happy with drill sizes then open up the hinge parts of the wing. Tap in the bushings, and wick in a drop of thin CA just to make sure.

Re-assemble the flaps and ailerons using the 10BA screws as before.

This should prevent the screw threads eating away at the glass board

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Hope this helps

Cheers

Danny

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I saw discussion of this issue. Does the design have the threads of the screws as the bearing and load bearing surface? That's bad practice even if the connection doesn't move. I suppose there's no possibility of screws with appropriate non-threaded length? I'd worry that the thread will chew into the brass bushing in time.

Or have a single length of brass tube passing through both fibreglass parts and acting as the axle, with the screw and nut tight axially on the tube?

Just random thoughts. Controls failing on a model like this don't bear thinking about.

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20160622_180820.jpg20160622_180842.jpgI'm having real trouble with the ailerons, they won't return to centre. Either the push rods are not thick enough and have too much bend, or the the holes that the push rods connect too have worn away? Cheesed off cos it means surgery to get at the servos. My fault really, I should have made servo hatches! Anyway here's a few pictures of the now, not completed model20160622_180921.jpg

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Oh thats not good John, looks great though
With hindsight i am not sure bellcranks were a good move these days, with the cost and power avalable. But then you have accesibilty issues so its swings and roundabouts.
Mine arent as accurate as individual servos but I think it will be okay. Binding is the real killer with bellcranks.
Keep at it chaps, nearly there
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