Aqua Star by Herr Engineering Co

13 Jun 20 - Added photos of the chines.

No of launches / Time 22 4 hr 1 mins
Wingspan 42.5 " 108 cm    
Wing Area 278 in2 17.9 dm2    
Flying Weight 1 lb. 2.7 oz 531 g with either pack  
Wing Loading 9.7 oz / ft2 29.6 g/dm2    
Wing Cube Loading 7.0 - Trainer  
Motor Typhoon 6 brushless (High-End Technology)
Propeller Ramoser Technik & Design VarioProp 6.2" 3-blade, set at approx 3" pitch
Batteries 3S2P E-Tec 700 mAh LiPo  or a 3S Kokam 15C 910 mAh LiPo
Speed Controller Castle Creations Phoenix 10 - 10A - 5 to 16 cells - BEC & Brake - Programmable cut-off voltage
Receiver / Battery Webra Nano S6 - 6ch - PPM - 35 MHz
Servos Ailerons - 2 x JP Naro
Elevator - Hitec HS-55
Rudder - Hitec HS-55
Static motor parameters  3S2P E-Tec 700 mAh LiPo gave 9.7A @ 9.6V giving 11700 rpm @ 93W, approximately 80W/lb. The full throttle motor run is approximately 10 minutes.
Flight performance Tested from hand-launch. Climb is very steep at over 30� on full power, which is promising for water take-offs. The model will perform most aerobatic manoeuvres with loops from level flight being simple (not too surprising at 80W/lb.). The model will float around with almost no power so extremely long flight will be possible.

Tests on water. Several uneventful take-offs, skips and touch & go's completed using the Kokam pack.  Due to the plentiful power the take-off distance is about 5m (17 ft.) even when not on a smooth surface.

13 Jun 20 - I realised I'd never added photographs of the chines I'd fitted to the forward hull, which were fitted in 2 pieces each side, the forward section being added after the larger rear pieces.  The chines are pieces of ice-cream tub cut to shape and super-glued in to a slot, cut approximately bisecting the change in hull profile, so the outer end is significantly below the point of entry to the hull.  I used some Roket Powder to provide some reinforcement of the joint by adding a fillet either side of the chine.  After fitting the initial piece of chine to each side the nose lifted much quicker and there was less spray entering the propeller disc.  I decided though that handling could be improved further by adding another section in front of the existing piece as the nose curves up towards the front.  The second piece has therefore a steeper angle to the water and more moment arm than the rear section.  There is still some spray but it is further reduced putting less load on the motor and propeller.

20 Nov 17 - The hatch has been reinforced and a 2.4 GHz receiver installed; ready for flight again.

14 May 14 - The Aquastar battery hatch had warped and it is therefore sitting in my work room awaiting repair and conversion to 2.4 GHz.

5 Sep 07 - Finally managed to complete some water take-offs from a river at the edge of the sea in Rhosneigr, Anglesey, Wales.  The surface was fairly smooth with only a 25 mm (1") high ripple to contender with.  As expected the take-off run was only a few metres and was uneventful.  I also completed a number of surface skips, with the hull just touching the water and climbing away, and several water touch and go's with a short period of surface running before powering up and climbing away.

I have also been flying lately with a 3S Kokam 15C 910 mAh pack which only weighs 77g and requires 29g of lead in the nose to maintain the balance, giving the same flying weight as the E-Tec packs.  The advantage is that the Kokam pack provides slightly more voltage and therefore power and the duration is still in excess of 10 minutes.

24 Apr 04 - I add the bow spray rails, which I made from an ice cream tub rather than ply (much less likely to get waterlogged). I managed to use a friends pond the other day to do floating and taxi trails. The Aqua Star sits lower in the water than expected. This is despite being slightly below the stated weight of 19 oz. Only a small part of the rudder is below the water, but it is very effective at manoeuvring even cross wind. The only slight snag being that the 'tip' floats can be forced under the surface quite easily.

At slow speeds there is quite a bit of spray from the bow as the spray rails are under the water. As speed builds (very quickly) the spray reduces. On the final run the model was accelerated on full power and the spray stops as the spray rails emerge from the water. The model then accelerates even more quickly as air is forced between the hull and the water. The model almost got airborne (in about 5m (16 ft.)) and collided with one of the floating islands. The impact broke the leading edge strip between 2 ribs. Fortunately the repair only took a few moment with some 'cyano'.

11 Apr 04 - The model has been modified to have ailerons as I don't particularly like rudder/elevator models. This meant redesigning the float mountings as the original system would not have allowed ailerons. The wing chord has been increased by approximately �" (6 mm) due to the addition of an additional trailing edge strip in front of the ailerons. I have completed the model and test flown it today (see above).

[ Back ] [ Electric Aircraft ]