Sig LT 25
July 2003
| Dads Day, 2005 |
Contents
General Specifications
Build Date - July 2003
| Airframe Type - | Top Wing | Flying Type - | Sport/Float | |
| Wingspan = | 63 inches | Length = | 51 inches | |
| Wing Area = | 724 sq. inches | Plane Weight = | 78 ounces | |
| Motor - | Turnigy SK4250-650 | Wing Load = | 14 oz/sq. ft. | |
| Propellor - | 13 x 8 APCe | Power = | 1100+ watts | |
| Thrust = | 128 ounces | Thrust/Weight = | 1.64 | |
| Battery Type - | Lipoly 5s1p | Capacity = | 3300 - 5000 mah | |
| Speed Control - | Turnigy Plush 60 amp | BEC - | External 4.8v |
Commentary
Back when I built planes as a teenager I always wanted a good sized high wing plane and I scratch built a Taylorcraft from model plans. That plane had an OS Max 15 and an Orbit 27mhz 4 channel set-up which by todays standards was huge in every way. It did fly and it flew very well but it didn't last long as I augered it into a cliff face while flying in some pretty decent wind at the ocean in SoCal. I learned a lot from that experience however and the desire for a high wing never left.
Fast forward a few decades and it wasn't long after picking the hobby back up that I started dreaming about the Taylorcraft again. I was well into the smaller planes and past the destruction of the Wattage Extra. I found the same model plans for the Taylorcraft and when I really looked at the amount of work involved I changed direction and started looking for a good, solid kit. I found the Sig LT25 and decided I could make it a fine electric convert.
In the build I did very little to change the kit. I made the wing bolt-on, added a second wing servo, created a battery tray and left everything else as is (somewhat heavy, but tough). For power I spent hours researching and settled on a Mega 30 brushless with a 2:1 SuperBox gear, a 12 x 8 prop and a 10 cell C size powertube. The plane weighed in at around 90 ounces which was within the kit spec although heavy. It flew beautifully. Very smooth easy take-offs and landings, no surprises. It was a dream come true.
That all started in 2002/2003. I subsequently changed it over to LiPoly using a 4S2P pack which dropped the all-up weight to around 82 ounces. I then tried my first Chinese motor, a BP3520 from BP Hobbies and a 13 x 8 prop and what a difference this made in power and aero batics. Not to mention flight times in the high teens. Amazing.
Now (middle of 2009) I still have the same motor but I have changed to a PolyRC 4S1P 3300 pack which drops the weight to around 72 ounces which is very light for this plane and it shows for now, vertical is no problem and it is quite an exciting plane to fly. It has enough power to literaly jump off the water when on floats and the flight times are still in the 12 to 15 minute range. In retrospect I'm glad I didn't change the kit much. It didn't need it, it is very well designed (obviously because it still lives!) and it is still a beatiful flier.
UPDATES
While this plane has gone through constant mild changes over the years, I am now (early 2011) doing a bit more significant upgrade. Changes include a power upgrade (shown above) which nearly double the amount of available power, Tail feather rebuild, Complete Wing re-do and all new servos. I also removed the side camera mount and changed the color scheme a little.
Power Upgrade Power upgrade comparison
| Previous | New | |
| Motor: | Balsa Products BP3520-7 | Turnigy SK42-50-650 |
| Battery: | 4S1P 20C 3300mah | 5S1P 30C 3300mah |
| Power: | 780 watts | 1200 watts |
| Prop: | 13 x 8 APCe | 13 x 8 APCe |
| Thrust: | 98 ounces | 128 ounces |
| Prop Speed: | 61 mph | 71 mph |
Tail Feathers
Wing Reconfigure
