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Taltos by Ray Jennings

 

A reinterpretation of a classic

vintage 2.5cc contest power design

 

Article by Ray Jenings

with captions by Andrew Gibbs

Taltos electric vintage model airplane

Having converted an enlarged Korda Wakefield to electric power I decided to try the same exercise with an FAI F1C free flight power design. The Korda, which was shown in the February 2008 issue of AMI flies well but is very lightly built and best suited to calm weather flying, whereas a power design would be a little more versatile and rugged.

There are many vintage designs to choose from and a quick look through my collection of old Aeromodellers led me to the cover of the January 1964 issue. This showed the famous Hungarian modeller Erno Frigyes holding his 1963 World Champs winner, the Taltos (Pegasus). Inside the magazine I found a short article and a dimensioned three-view drawing – perfect. I scaled the outline to the actual size (60”span) but simplified and strengthened the structure somewhat.


Taltos vintage model aircraft

2 Erno Frigyes is seen here the cover of the January 1964 issue of Aeromodeller, holding his winning Taltos model.


Taltos vintage model aircraft plan free flight

3 I love looking at plans, old or new. Ray kindly provided a scan of the Taltos design from which he drew up his own plan.

Construction was straightforward although I built the tail plane almost entirely from 1/32 balsa to keep it as light as possible. The only cheat was to widen the fuselage slightly to squeeze in all the gear. The covering is World Models Toughlon, red on the fuselage and transparent yellow on wing and tail plane, using a simplified version of the original’s scheme. The finished weight of my model, with its battery is 34ozs. Erno’s Taltos weighed 27ozs.


electric vintage RC model

4 An impression of the model’s 66 inch span can be gained here.


Power system of an electric vintage RC model aeroplane

5 The nose area of the Taltos, seen from underneath. The motor is an AXI 2808/24, turning a Graupner 9 x 5 Slim Prop. ESC is a Jeti Advance 30 Plus

Radio used is a 2.4GHz Futaba T6EX with an R606FS receiver and two Hitec HS82MG servos. Motor is an AXI 2808/24 turning a Graupner 9 x 5 Slim Prop and the speed controller is a Jeti Advance 30 Plus.


rc system electric vintage rc model aircraft

6 The rear of the equipment area showing the servo installation. The magnet’s location can also just be seen, directly under the structure of the pylon.


Tail surfaces electric model airplane

7 Ray has preserved the model’s character by making the hinged control surfaces blend with the tail surfaces. The original design has a two position horizontal tail plane to cater for powered and gliding conditions. Of course the elevator on Ray’s RC version means this was one detail that he didn't need to reproduce.

To help with the balance I used heavier Saphion cells rather than Lipos, in this case a four cell 12.8v 15C pack of 1,200mAh capacity. This combination, according to my old Astro Flight Wattmeter, produces an input power of 160 Watts. RPM on the 9 x 5 is 9,400. As regards balance, the original used a 68% wing chord CG. This worried me a little so I balanced mine at 60%.


Taltos electric RC model aircraft

8 The equipment access hatch is located underneath the nose of the model. This position is necessary because of the location of the wing pylon. The pylon structure can be seen in this view. The hatch is held by a tongue at the front, plus a magnet in the middle, directly under the pylon. The 4-cell Saphion pack can be seen along with the ESC.


cooling hole for electric rc model plane

9 The hole in the access hatch is for a finger to remove it. The hole also acts as an exit hole for cooling air. Ray says that his club rules call for a 15 second motor run only, so cooling is not a problem. Ray always flies to these rules, even for fun – he says the model looks stupid doing anything else, especially aerobatics.

 

This type of model is for climbing high and gliding long. It looks ridiculous doing overshoots, hedgehopping and aerobatics. The climb is fast and steep but it’s no hotliner. The motor was selected as theoretically having the equivalent power of a 2.5cc two stroke as used in FAI F1C models. Since I have never actually seen these fly, I don’t know if the climb is realistic or not, but it’s fast enough for me. Just for fun I entered it in a local contest and came second. I think this was mainly due to blundering into good air although the performance seemed to be on a par with a typical two meter electric glider.

In truth the Taltos was my second choice design. I really wanted to build one of Bill Giesking’s futuristic looking flapped designs but fortunately common sense prevailed. But who knows, perhaps next time……….

 

Taltos electric power system data
1 x 4S 1,200mAh 15C Saphion battery
  Prop RPM
(9x5)
Voltage
(on load)
Current
(Amps)
Power
(Watts)
Pitch speed
Full throttle 9,400 12 13 160 n/a

 

Taltos technical data
Span 1,524mm 60 inches
Length TBA TBA
Flying weight
964g 2lb 2oz
(34oz)
Wing Area 0.29 sq m 449 sq in
Wing Loading 00 g/dm 28 oz/sq ft
Battery 1 x 4S 1,200mAh Saphion, rated at 15C
Nominal battery voltage 12.8V
Motor AXI 2808/24
Motor Kv (design RPM/V) 1,190
Prop Graupner 9 x 5 Slim Prop
RPM at full power 9,400
Propeller pitch speed 47mph approx
Current at full power 13A approx
Max Power 160W
Power Loading 158W/kg 72W/lb
Control functions Rudder, elevator and throttle.




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