Discus maiden

[harry curzon]

On Tuesday I travelled to White Sheet hill and did the maiden flight of my "new" 4 metre Discus, which is primarily intended for bringing to the scale aerotow meetings, rather than sloping. It's from the Graupner kit of mid 1980s era and weighs 4.4kg. It flew absolutely perfectly, from launch it just went straight forward and was hands-free until I needed to turn. It's very rare that I bring a model back from a maiden without wanting to change the CG, trims, control rates etc so I was very chuffed with the Discus. I don't like its blue canopy, I think that was a fad in the 80s? I took it to Sarik to see if they had something from another model that would fit but there was nothing close enough that it could be fettled. I have so many building projects that are always behind schedule so I don't know if I can allocate time to carving a plug to make a clear canopy.

I bought the Discus second hand, built and had been flown once by its builder but I stripped it down to install HV servos and removed 10 feet of heavy mains electric cable from the wings!! That was replaced with Powerbox premium cable. I had to use chemical stripper to remove the vinyl emulsion paint, filled most of the problems, and then repainted with Klass-Kote epoxy paint. The original owner had modified the wings to have 4 servos for ailerons and airbrakes instead of the original 80s design with servos in the fuselage. I use HV servos as I am moving over to using two lithium ion batteries through a Jeti V cable (battery backer). I make my own 2S Li-Ion batteries for about £5 each by getting Dell/HP laptop packs from ebay for under £15, break open the plastic case and inside are 6 standard Li-Ion cells. They have spot welded tags so it is easy to solder on the power cables and a balancing lead.

Also with me on Tuesday at White Sheet was my 3 meter Pilatus B4 from the Royal Models artf. I bought the red and blue vinyl to make the sunburst pattern which for me is an essential part of the B4!

[FrankS]

Very nice.

Was up on Garway Tuesday, you'll maybe have to join us there one day.

[harry curzon]

Will do Frank, but does it have a nice big flat area for landing big scale gliders? I don't like risking them on small rocky slopes!!
What winds does it suit and where is the slope and the parking?

[barrieburton34]

Harry,how do you charge the batteries?I did the same as you,used laptop cells,but I am having trouble charging them,I do not have a Lion setting on my charger.

Barrie B

[harry curzon]

Harry,how do you charge the batteries?I did the same as you,used laptop cells,but I am having trouble charging them,I do not have a Lion setting on my charger.

Barrie B

Barrie, I charge them on the Lipo setting!
Before you think I am bonkers, I first started using Jeti Power-Ions. They are Li-Ions but the specs say max voltage 4.2V per cell, which is lipo not Li-Ion voltage. I emailed Jeti about it and I had it in writing from them to use the Lipo setting on the charger. The Li-Ion setting would stop at a lower voltage which is "safe" but would be below fully charged so you get well below the claimed capacity. I have always charged Jeti Power-Ions as lipos so when I started making my own I took the view that they are very probably the same cells so I have always charged them on the lipo setting and they have been fine with that. I always use the balancer while charging.

Since I normally use two batteries in parallel with a backer, and I have telemetry with voltage warning, I think it mitigates any risk that the ebay batteries may have a dud cell in them.

[FrankS]

Will do Frank, but does it have a nice big flat area for landing big scale gliders? I don't like risking them on small rocky slopes!!
What winds does it suit and where is the slope and the parking?

Harry

Yes, big flat area on top covered in braken/ferns for a soft landing, best wind is NW round to SW, but also gets great thermals in the valley to the South.

https://getoutside.ordnancesurvey.co.uk ... efordshire you have to drive up a farm track to the parking and then walk the rest of the way up, not as much a climb as the Malverns, but it's not a drive to the top like Selsey. Here's some video shot from a scale glider

[harry curzon]

Thanks Frank, lovely video, enjoyed watching that.

Is this the car park? https://www.google.co.uk/maps/place/Gar ... -2.8094959

[FrankS]

Yep, park, walk through the gate an follow the main track to the top.