Crossfire (X-Fire) - by Howard Metcalfe Models

5 Jan 03 - New motor and tail wheel fitted.

Crossfire - Front Crossfire - Front Quarter - Port Crossfire - Port Crossfire & Synergy slope side

N of launches / Time 44 5 hours 27 mins Figures are total for all variants
Wingspan 54.8 " 1.39 m The weights shown below exclude the optional undercarriage. If fitted the increase is 85g (~3 oz.)
Wing Area 384 in 24.8 dm
Flying Weight 2 lb. 13 oz. 1.28 kg 2 lb. 12 oz. 1.26 kg
Wing Loading 16.9 oz/ft 51.6 g/dm 16.6 oz/ft 50.7 g/dm
Wing Cube Loading 10.3 - Just over Aerobatic (OK by me) 10.2 - Just over Aerobatic (still OK)
Motor Fanfare Gold (BB Graupner Speed 600 Race 8.4V) Model Motors AXI 2820/10 sensorless brushless
Propeller Graupner Slim 8" x 4" (20.5cm x 10cm) Aeronaut Carbon 10.5" x 6" (27cm x 15cm) folder 
Batteries 8 Sanyo RC-2000 or other sub-C cells 10 Panasonic 2000mAh NiMH (4/5 Sub-C)
Speed Controller Jeti JES 500 - 6 to 12 cells - 50A - BEC - Brake Model Motors 4016-3ph - 40A - 7 to 16 cells - BEC & Brake
Receiver Webra Nano S6 - 6 channel - 35 MHz
Servos Flaperons - 2 x Union Micro UM-9G
Elevator - Hitec HS-81MG
Rudder - Hitec HS-81MG
Static motor parameters  8 Sanyo RC-2000 give 13000 RPM @ 7.9V drawing 36A, estimated input 105W/lb, output 67W/lb 10 Panasonic 2000mAh NiMH (4/5 Sub-C) give 8100 rpm @ 27.9A and 10.0V, estimated input 100W/lb. => output 79W/lb. (much more efficient).
Flight performance Without undercarriage: I can describe it in one word - AWESOME. Climb out speed is steady at about 45 and height gain is at an amazing rate. All manoeuvres are really smooth and loops can be huge. With the flaperon mode operating vertical figure 8s can be completed even after 4 minutes running. Landings can almost be at walking pace with the flaperons down, and I even had it hovering in a less than 15 mph windspeed. Even soars on the slope with a decent wind.

With undercarriage: The take-off is uneventful with the model tracking straight. Once in the air the undercarriage does add a noticeable amount of drag when doing vertical manoeuvres. I will only fly with the undercarriage when needed for specific tasks or flying from a hard surface.

Without undercarriage: Never evaluated

With undercarriage: Never evaluated

29 Jun 03 - Whilst flying today I pancaked the model, which caused considerable damage to the fuselage. The fuselage is effectively irreparable, but the wing could be reused. I probably build another fuselage to use this power train, but it will be a different design as building the original was a lot of work.

5 Jan 03 - I decided towards the back end of the season that I would fit a more powerful motor for next season. I bought a Model Motors AXI 2820/10 sensorless brushless motor, which is much more efficient than the Speed 600 Race. I have completed fitting the motor and also added a tiny tail wheel (the skid had snapped off anyway). I decided that the input power should remain about the same, but the increased efficiency of the brushless motor and bigger propeller will give a performance advantage. The other advantage is that I gone up to 10 cells, reducing the input current and increasing the motor run time. It will be interesting to see whether the flight time increases. I have scope to increase the power available by increasing the propeller, but I'll need to move to Sanyo CP1700 cells to move above 30A. As the motor is smaller and lighter and the battery pack about the same weight, the model is actually about 0.7 oz. (20g) lighter than before.

1 Jan 02 - I have repaired the cracked wing screw mounting black and fitted the undercarriage whilst doing it. The reason for fitting undercarriage is to complete the BMFA Power "B" Certificate, which requires take-off and landing using wheels (hand launches are not permitted). With the undercarriage fitted the weight of the model increases by 85g (~ 3 oz.) which I consider acceptable. The undercarriage is the folded Dural plate type with axle posts and slim wheels to minimise drag. I also had to add a skid, a piece to 2 mm carbon rod, to the tail to make the rudder clear of the ground with the undercarriage fitted. The Dural plate is bolted to the model with 3 M4 Nylon screws so can be removed almost instantly. I doubt that I'll fly with the undercarriage on unless I want to practice. Hopefully I'll get chance to take a photograph of it soon.

29 Dec 01 - I need to make a slight repair as one of the wing mounting screw blocks has cracked. Whilst I'm at it, I'll also be introducing a hard point to attach an undercarriage to.

29 Oct 00 - I took my Crossfire to the slope with me today as an experiment and temporarily fitted an Aeronaut 7" x 4.5" (175 x 115mm) folding propeller to minimise drag. The wind speed was high, between 25 and 35 mph (40 to 55 km/h) and almost square to the slope. The additional weight of the motor and 8 cell battery didn't seem to hamper performance and all the normal aerobatic manoeuvres were completed. I completed a 10 minute flight without using the motor. I will test the performance of the model with the Aeronaut folding propeller as it would be preferable to the fixed bladed Slim propeller. I've also added a photograph taken on the slope with my Synergy and one of John Steven's gliders.

22 Oct 00 - I managed to complete the first flights today in superb conditions. The performance is really impressive and is described above.

21 Oct 00 - Construction finally completed after a period of about 3 years. I have covered the model with a mixture of materials. The majority is covered in Easycoat with the fuselage in Gold and the tail surfaces, main wing ailerons, underside & upper surface tips in Silver. The canopy is covered in Dark Blue Solarfilm and most of the main wing upper surface is covered in Red and White check Profilm (Oracover). The check covering is really great as you are applying a normal film, but you get the benefits of conspicuity and orientation. It is more expensive than a plain film, but you more than save the cost in the time saved in applying it. The left (3) photographs above are the first shots I have used from my new digital camera. It is really easy and quick, giving great results.

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