Rienk
Well-Known Member
Well, I haven't given up on this project, but I wanted to get rid of the poll :ermm:
I keep wondering about the whole 103UL thing… it’s hard not to consider the options for making a truly inexpensive RTF aircraft, and realizing that the weight limit will be hard to meet – but going LSA is doable – even if the aircraft is not much heavier than 103. The problem again becomes flight training and expense… the beauty of 103 is limited training, no insurance requirements, etc.
I can’t help but think a fully rotomolded fuselage would be amazingly cheap. If we could get a fairly consistent 1/16” wall thickness (or less), the fuselage shell on something like the Solo would weigh about 60-80 lbs (depending on the plastic, and if it is glass reinforced). This doesn't seem to be a lot more than the weight of fabric and paint – if you take into account the extra structure required to hold an aerodynamic shape.
This would be in addition to the metal sub structure required.
If we picked a wing loading between UL and LSA – I’ll arbitrarily pick 7 – then a plane with a gross weight of 700 lbs would need a wing area of 100 sf. If that were rotomolded, the wing shell would weigh another 60-80 lbs – which is about double what composite would be. Thus, there would probably only be 60-80 lbs extra compared to the UL, which is really nothing in the grand scheme of inexpensive flight.
This is even less of a concern in the two seat version – which makes me wonder if it should be the only model made (no 103UL, but maybe both low wing and high wing LSA variants). If we assumed 1000 lb gross weight, wing loading of 7 (thus wing area of 140 sf), total surface area would probably be less than 600 sf, for a shell weight of 180-240 lbs – likely an extra 100 lbs over other building methods. If that building method can bring the cost of a “basic” LSA trainer below $35k, I think it will be a winner (assuming it looks good and flies well).
If the metal sub-structure were beefed up, the same wing would work at full LSA gross weight (1320 lbs) and give adequate wing loading for LSA stall speed!
Still to be determined:
Those are my latest thoughts. Comments?
I keep wondering about the whole 103UL thing… it’s hard not to consider the options for making a truly inexpensive RTF aircraft, and realizing that the weight limit will be hard to meet – but going LSA is doable – even if the aircraft is not much heavier than 103. The problem again becomes flight training and expense… the beauty of 103 is limited training, no insurance requirements, etc.
I can’t help but think a fully rotomolded fuselage would be amazingly cheap. If we could get a fairly consistent 1/16” wall thickness (or less), the fuselage shell on something like the Solo would weigh about 60-80 lbs (depending on the plastic, and if it is glass reinforced). This doesn't seem to be a lot more than the weight of fabric and paint – if you take into account the extra structure required to hold an aerodynamic shape.
This would be in addition to the metal sub structure required.
If we picked a wing loading between UL and LSA – I’ll arbitrarily pick 7 – then a plane with a gross weight of 700 lbs would need a wing area of 100 sf. If that were rotomolded, the wing shell would weigh another 60-80 lbs – which is about double what composite would be. Thus, there would probably only be 60-80 lbs extra compared to the UL, which is really nothing in the grand scheme of inexpensive flight.
This is even less of a concern in the two seat version – which makes me wonder if it should be the only model made (no 103UL, but maybe both low wing and high wing LSA variants). If we assumed 1000 lb gross weight, wing loading of 7 (thus wing area of 140 sf), total surface area would probably be less than 600 sf, for a shell weight of 180-240 lbs – likely an extra 100 lbs over other building methods. If that building method can bring the cost of a “basic” LSA trainer below $35k, I think it will be a winner (assuming it looks good and flies well).
If the metal sub-structure were beefed up, the same wing would work at full LSA gross weight (1320 lbs) and give adequate wing loading for LSA stall speed!
Still to be determined:
- finish – color and protection.
- Acceptable fuselage shape, and required metal structure.
- Rotomolding tooling costs.
- Ability to have framework pre-installed into rotation mold (so parts are made around structural components)
Those are my latest thoughts. Comments?