I received the scans and wanted to share a few to show the level of detail in Gus' plans. Looks just like a set of model airplane drawings with complete pattern templates.
Sure looks like it would make a fun build and capable flyer.
A couple of years ago there was a thread at RC Groups by several guys interested in the Gus Briegleb-designed BG-12. It's an interesting sailplane with impressive performance for a 1956 home-builders design and kit. Last year on my visit toTehachapi I was fortunate enough to help Raul Blacksten remove his ship from its trailer and assist in assembly. I took a few photos but nowhere near enough time to do a full study for drafting plans for a model.
Then a couple of months ago, Herbert Eberbach who has completed several build logs here expressed interest in the Briegleb and coincidentally, Mark Nankivil emailed me just a week ago offering me a set of blueprints given him by Wabash Valley Soaring Association pilot Jim Croce. The prints arrived a couple of days ago, more than 30 sheets I think and they are impressive. I agree with Mark and Herbert that it will make a great scale sailplane model and my work in developing a kit has just been shortened by weeks.
Here are the specifications and brief history courtesy of the Sailplane Society of America Sailplane Directory:
Span 15.24 m./ 50 ft
Area 13.1 sq. m. / 141 sq.ft.
Aspect ratio 17.7
Airfoil NACA 4419R, 4406R
Empty weight 227 kg. / 500 lb.
Payload 113 kg. / 250 lb.
Gross weight 340 kg. / 750 lb.
Wing loading 25.95 kg. / sq. m. / 5.3 lb. / sq. ft.
L/D max. 34 90 kph/ 49 kt/ 56 mph
Min. sink 0.69 m/s / 56 fps / 76 kt
76 kph/ 41 kt/ 47 mph
Country of origin USA
Designer William G. Briegleb
No. of seats 1
No. kits sold about 350
No. in the U.S. approx. 75
The BG-12 series has established an enviable record as a homebuilt sailplane with around 350 kits or sets of plans having been delivered to customers. The prototype flew in 1956 using a modified BG-6 fuselage. The –12A production version has a 15% thick three-piece wing. A lighter two-piece 18% thick wing was developed in 1963 as the –12B. Both have flaps for glidepath control. One flapless –12C model was built with a two-piece 15-meter span wing with air brakes to meet FAI/OSTIV Standard Class requirements. The –12BD model eliminates three degrees of wing twist, accomplishing the same effet by an aileron linkage applicable only in the low-speed range.
The Briegleb BG-12/16, which first flew in 1968, uses a new lower-drag fuselage topped off with a swept-forward tail. The horizontal tail surfaces are of thestabilator type including two anti-servo tabs to produce good stick feel. L/D max. is 36.
A number of modifications were incorporated by individual kit builders. One example is the Niedrauer NG-1 which has a BG-12/16 fuselage with a –12B tail and cockpit depth reduced by 9 in /23 cm to 34 in /86 cm, and lengthened to accommodate the pilot in a semi-reclining position. Specifications are for the BG-12BD.
Here are several other interesting links to information and photos of the Briegleb: