Hi all. I've been doodling a while, my first doodles many years ago were overly complicated, different for the sake of being different and wholy impractical, but i think my latest doodle has some merit to be explored. I'd like to build it, but time will tell. life has a habit of getting in the way of these things.
Here's my doodle:
This thread is intended to be a discussion on the details. How things might work, and be constructed. Ironing out details, suggesting alterations etc. Please don't be that guy who says 'just build X, Y or Z' - they're pretty much the same.
Here are the intended categories:
FAR 103 - (Empty weight - 254lbs/115kg Stall - 24kts Max cruise - 55kts)
SSDR (UK) - (MTOW - 661lbs/300kg Stall - 35kts)
Sub 70kg (UK) - (Empty weight - 154lbs/70kg Stall - 20kts)
The wing is sized for the Sub 70kg category which allows it to meet all the above regulations with a MTOW of 170kg, however MTOW will be set at 300kg for the purposes of structures. (Even though you'd need to be a rather large pilot) because i can see this being on floats in the SSDR and possibly 103 category ;-)
Features i want:
Keep it in my garage or an enclosed trailer (Limits length to 16' wings folded)
wings fold for the purposes of above. Simple as possible rigging.
off airport fun - STOL - low and slow (big tyres, forgiving suspension, stable at low speeds)
Construction:
I'm going to concentrate on the smaller parts before the bigger parts. Weights of big things can be easily estimated or googled (Wings, fuselage, powerplant, fuel tank, tyres etc). It's the little bits that will add up which is why nothing is getting built until every component is modelled. The fuselage will be vacuum infused carbon sandwich. My weight estimation is based on 2x200gsm/6mm pvc foam/2x200gsm as the layup which comes to 12.06kg for the basic 'tub' excluding local reinforcements.
The wing i had intended to make rutan style with solid xps foam core due to the short chord/low volume/high AR. using the same layup schedule of 2x200gsm at +-45 on 32kg/m2 XPS core.
Wing (Left): Main wing: (Foam 9.35kg - skins 2.86kg - total 12.21kg) Slat: (Foam 0.72kg - skins 0.74kg - total 1.46kg) Flap: (Foam 0.42kg - skins 0.63kg - total 1.05kg) TOTAL 14.72Kg
Wing (Right): As Above (14.72kg)
Fuselage Tub: Internal skins 4.75kg - external skins 4.75kg - PVC core 2.56kg TOTAL 12.06kg
so with the big bits out the way we have a total of 41.5kg
Powerplant: I've been looking at the Bailey v5 Paramotor engine:
Engine weight 15.2kg (complete with all ancillaries)
Capacity 210cc
Power 20.5hp
Static Thrust (1.3m propeller) 60kg
Fuel consumption 2-3l/hr cruse
4 stroke, 2 valve, overhead camshaft.
Unique Bailey 'easy start' System.
Oil Capacity 500cc
Forced Air Cooling
CDI ignition
Add 10L of fuel (3hrs endurance) that's 7.7kg plus a tank, call it 8kg
That's us up to 64.7kg!
Still left we have landing gear, control system, struts, folding mechanisms, rudder and horizontal stab, cushion, windscreen, minimal avionics. Fair to say it's not going to meet 70kg empty weight at that, so can anything be changed? I could increase the flaperon chord and reduce the main wing chord to eat volume out the foam, as an example. reduce internal fuselage skin thickness, use less pvc foam (calculated for a solid layer but it would be smaller pieces on flat areas). But if its not going to be sub 70kg, then it would be interesting to see how close it could get.
I was dabbling around with landing gear geometry and construction ideas lastnight. I watched a video about 'forged' carbon fiber. basically compression moulded chopped fibers in 3d printed moulds. would need to do some testing first but i'll post a screenshot of my idea. uses carbon tubes (stock sizes) with the joints being this solid forged carbon. any hinge points are basically a brass tube wrapped in FG, squeezed into the bigger hole in the carbon part, then nylon washers either side so everything is electrically insulated and low friction. I might just go back to bungee cord but this one was to have 270mm shock springs to add dampening. 300mm travel and 4.2deg camber change over the full range. Maybe a sub 70kg version would need a solid gear with little wheels but that kind of defeats the goal.
So, let's throw some ideas around
Here's my doodle:
This thread is intended to be a discussion on the details. How things might work, and be constructed. Ironing out details, suggesting alterations etc. Please don't be that guy who says 'just build X, Y or Z' - they're pretty much the same.
Here are the intended categories:
FAR 103 - (Empty weight - 254lbs/115kg Stall - 24kts Max cruise - 55kts)
SSDR (UK) - (MTOW - 661lbs/300kg Stall - 35kts)
Sub 70kg (UK) - (Empty weight - 154lbs/70kg Stall - 20kts)
The wing is sized for the Sub 70kg category which allows it to meet all the above regulations with a MTOW of 170kg, however MTOW will be set at 300kg for the purposes of structures. (Even though you'd need to be a rather large pilot) because i can see this being on floats in the SSDR and possibly 103 category ;-)
Features i want:
Keep it in my garage or an enclosed trailer (Limits length to 16' wings folded)
wings fold for the purposes of above. Simple as possible rigging.
off airport fun - STOL - low and slow (big tyres, forgiving suspension, stable at low speeds)
Construction:
I'm going to concentrate on the smaller parts before the bigger parts. Weights of big things can be easily estimated or googled (Wings, fuselage, powerplant, fuel tank, tyres etc). It's the little bits that will add up which is why nothing is getting built until every component is modelled. The fuselage will be vacuum infused carbon sandwich. My weight estimation is based on 2x200gsm/6mm pvc foam/2x200gsm as the layup which comes to 12.06kg for the basic 'tub' excluding local reinforcements.
The wing i had intended to make rutan style with solid xps foam core due to the short chord/low volume/high AR. using the same layup schedule of 2x200gsm at +-45 on 32kg/m2 XPS core.
Wing (Left): Main wing: (Foam 9.35kg - skins 2.86kg - total 12.21kg) Slat: (Foam 0.72kg - skins 0.74kg - total 1.46kg) Flap: (Foam 0.42kg - skins 0.63kg - total 1.05kg) TOTAL 14.72Kg
Wing (Right): As Above (14.72kg)
Fuselage Tub: Internal skins 4.75kg - external skins 4.75kg - PVC core 2.56kg TOTAL 12.06kg
so with the big bits out the way we have a total of 41.5kg
Powerplant: I've been looking at the Bailey v5 Paramotor engine:
Engine weight 15.2kg (complete with all ancillaries)
Capacity 210cc
Power 20.5hp
Static Thrust (1.3m propeller) 60kg
Fuel consumption 2-3l/hr cruse
4 stroke, 2 valve, overhead camshaft.
Unique Bailey 'easy start' System.
Oil Capacity 500cc
Forced Air Cooling
CDI ignition
Add 10L of fuel (3hrs endurance) that's 7.7kg plus a tank, call it 8kg
That's us up to 64.7kg!
Still left we have landing gear, control system, struts, folding mechanisms, rudder and horizontal stab, cushion, windscreen, minimal avionics. Fair to say it's not going to meet 70kg empty weight at that, so can anything be changed? I could increase the flaperon chord and reduce the main wing chord to eat volume out the foam, as an example. reduce internal fuselage skin thickness, use less pvc foam (calculated for a solid layer but it would be smaller pieces on flat areas). But if its not going to be sub 70kg, then it would be interesting to see how close it could get.
I was dabbling around with landing gear geometry and construction ideas lastnight. I watched a video about 'forged' carbon fiber. basically compression moulded chopped fibers in 3d printed moulds. would need to do some testing first but i'll post a screenshot of my idea. uses carbon tubes (stock sizes) with the joints being this solid forged carbon. any hinge points are basically a brass tube wrapped in FG, squeezed into the bigger hole in the carbon part, then nylon washers either side so everything is electrically insulated and low friction. I might just go back to bungee cord but this one was to have 270mm shock springs to add dampening. 300mm travel and 4.2deg camber change over the full range. Maybe a sub 70kg version would need a solid gear with little wheels but that kind of defeats the goal.
So, let's throw some ideas around
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