Model construction: April 2011
Features of the model:
Wingspan: 1.32 m
Mass: 3.2 Kg
Wing loading: 96 gr / dm2
Engine: Dualsky 4120C V2
Battery: 6S / 4000mAh
Propeller: 14 × 7
A friend of the club who decided to stop model building gave me the planes that remained to be built. Thanks to him; o) Jamara’s Yak 54 is one of them.
This kit is an ARF. The fuselage is in fiber and resin, the rest in structure. Not much to do then, fix the landing gear, the tail wheel, the fixed plane and other odds and ends. Then install the controls and the radio.
The engine is entrusted at first to my faithful Twister 29 and the A123 5S2P Piper Pack. However, this engine is starting to age, a magnet is peeled off during engine tests. Repairing is easy with Araldite. We’ll see if it lasts over time.
The only difficulty in the construction of this model therefore lies in the fixing of the engine. I chose to apply the same method as for the Piper because it gave me all satisfaction: Front flange to hold the engine connected to the couple by 4 threaded rods of 3mm inside 5mm aluminum tube. It fits well and allows the adjustment of the down angle and the anti-torque.
The 1500mAh battery is attached near the engine as far forward as possible. It still took me about 150 gr of lead to get the most forward centering given by the manufacturer.
In principle I should be able to remove it after a flight centering test. It would be nice because the plane in flight weighs 3.2 kg which gives a wing load of 96 gr / dm2. It’s a lot…
The propeller is a 14×7 which does not overload the engine (pitch speed of 72 km / h, traction of 1.8kG and 500W).
The maiden flight took place on May 15 on Amcy field.
Takeoff:
The course is easy and the rudder very effective, it will be necessary to put some expo. The power of the Twister is not demonic and, given the wing loading, I let it roll over the entire length of the runway. the plane takes off with a moderate slope and gently climbs.
In flight:
The Yak is picking up speed and I feel the inertia in the resources, the trimmers are quickly adjusted but I am not very comfortable because the wing loading makes me fear the worst, but the plane seems healthy. As the weather was not ideal and the pilot was not very reassured, I would only loop and roll over. It works well but the engine is a bit tight for making beautiful and big curls. I land after 5 minutes of flight because a strange noise is heard.
Landing:
Finally this Yak seems nice, it is heavy but slows down slowly and does not flinch at low speed. the landing is going well.
The noise comes from the ballast which is not well fixed. Not serious but not careful. I will need one or two more flights to get a good feel for the plane, but in any case it is operational for the Crespierre meeting. It was the goal.
For the future it will be necessary to think of mounting a more powerful engine to get the most out of this Yak. In the meantime I’m going to test other, larger propellers.
Finally, the engine was happily replaced by a Dualsky 4120C V2 with 2 Accus 3S / 4000mAh pack in series and a 14 × 7 propeller.
The weight gain and better distribution of the equipment made it possible to center the aircraft without ballast. The power is now quite correct for this aircraft which is still tricky to fly with this very (too) large wing load.