Re: Lockdown :(

derry
 

The douglas fir ply called up in the plans is a very common construction ply in the States and very affordable.  Gus used this in his BG designs not for the strength but to get a good contour that doesn't get the 'starved horse' look with age.
The three of us in NZ that started building BGs imported DF ply from the states but when we received and inspected it decided it was not fit for aircraft use as it had quite big gaps in the inner ply and inlays where knots had ben cut out... Knowing what I know now, this was quite normal for that ply and unless you hand-picked each sheet you bought, this was the nature of the animal.
Maybe Gus had a better source of ply for his kits?  Anyway, our CAA approved the substution of readily available Island Kauri marine ply for skinning.  We knew there was a weight penalty but the quality of the ply was excellent. 
The BG12-16 design all up weight limit is 850 lb so cockpit load for mine is still good at 96kg, plus another 12kg if I remove the fixed ballast weights, givjng 108kg. 

On Sun, 19 Apr 2020, 23:27 Scott Johnson, <s_johnson@...> wrote:

The original parts used the American kit supplied ply I think (Douglas Fir ??). Construction was started somewhere in the early 60’s.

I used 3 mm and 1.5 mm Australian marine grade Hoop pine.

The original supplied 1/8 “ ply was only 3 layers. The 3 mm marine Hoop has 5 layers.

 

I don’t know what Laurie’s (GHJ) is constructed of.

 

Scott

 

From: BGsailplanes@groups.io [mailto:BGsailplanes@groups.io] On Behalf Of derry
Sent: Sunday, 19 April 2020 21:01
To: BGsailplanes@groups.io
Subject: Re: [BGsailplanes] Lockdown :(

 

Hi Scott.  I'm interested in what 1/8" skinning ply was used in the BG12s built in Australia?

 

cheers

Derry

 

On Sun, 19 Apr 2020 at 22:42, Scott Johnson <s_johnson@...> wrote:

Hello all,

Like Chris, I too was guided by Mike Burns on my build of the 12A.

Mike emphasised to stick to the plans and don’t add extra ‘cause it doesn’t look good enough. I did and the pilot weights are 78 kg to 124 kg.

I painted my BG in marine epoxy primer/sealer. 3 coats, and only added 1 kg to the fuselage. Water based house paint to give UV protection to the water protection. A bonus is that the epoxy will soften the house paint and bond through it – good news for repairs.

The negative with the house paint is that it softens enough on hot days (30 +) so that the tyre on the wing tip will stain the paint.

Again, Mike said that 1 gram extra at the tail is worth about 4 extra grams in the cockpit – I knew less than nothing about weight and balance at that time.

 

Hope some of my experience is helpful.

 

Scott

 

From: BGsailplanes@groups.io [mailto:BGsailplanes@groups.io] On Behalf Of derry
Sent: Sunday, 19 April 2020 07:30
To: BGsailplanes@groups.io
Subject: Re: [BGsailplanes] Lockdown :(

 

My ship is quite heavy due to the denser 1/8" ply I used and I am sure Steve also used the marine grade Island kauri as well.  Add to that mine also has epoxy/2oz glass sheathing all over.

At my flying weight of 800 lb the 12-16 has the wing area to climb as well as a PW-5 in scratchy thermals so you can rest easy.  The extra mass of the BG means it happily gets along on ridges or cloud streets above 70 kts. I often find myself hitting 90kts without any conscious effort.

Flying in choppy wave down south one time, the experienced K8b pilot flying with me complained that it was too rough for him whereas you barely noticed it in the 12-16... possibly lying back so much helps in this regard.

 

On Sun, 19 Apr 2020, 09:02 Derry Belcher, <dbelcher07@...> wrote:

Looking good Nick.  I'll weigh one of my stabilators today to compare, or maybe need to weigh both to average as one has the extra joiner tube.  I wouldn't lose sleep over the weight as the lead counter-balance weight for the stabilator is quite a lump. 🥴

 

 

On Sat, 18 Apr 2020, 19:04 , <soloflight@...> wrote:

I weighed one of my stabilators it is 2.8kg including the anti servo tab but without paint 

Join BGsailplanes@groups.io to automatically receive all group messages.