Fly Electric!

Mumbo Minor

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What do you call a small 3D model which can sting like bee, run like a scalded cat and goes berserk when you feed in 75 degrees of elevator movement? 'Mumbo Jumbo' is what came to my mind. Since I like the model so much I expect there to be a larger version so this one is 'Mumbo Minor'. I would like to acknowledge Christophe Paysante le Roux's magnificent Majestic which inspired this design.

I have started with a 171sqin / 29in span version. Most of the text applies to this version. However, I think the plane is too 'lively' so the plans are for the size I will build next, namely 197sqin / 31.3in...

The plane is designed for small CD-Rom brushless motors. My (171sqin) model weighs 5.8oz (AUW) and the motor produces over 12oz of thrust, more with fresh 3x340 Lipol cells. 'It does not lack power' would be the understatement of the year! It will accelerate vertically forever! I use a small GWS Rx, three 6g servos (HS50 or similar), Tsunami 10 or Jeti Advance 08-3P ESC, 3x340's and GWS 8x4.3 or APC SloFly 8x3.8 props.

The plane will knife-edge with ease including knife-edge loops! The rudder is very powerful and will turn the model through 180' in a flash. It will prop hang and do super head-over-heels tumbles if you can handle ridiculous elevator movements. It will torque roll with ease if you know how. Roll rate can be as brisk as you can handle. 60-70% exponential on most surfaces is the norm! So, it is VERY lively but with only a 3mm thick wing it the tips flutter with any speed.

Although it draws about 6A from fresh LiPoly's, most flights are over 8 minutes with constant 3D manoevours so average much lower. Stunning! The model is intended for indoor 3D flying in fairly small halls but handles a fresh breeze outdoors with ease (where mine spends most of its time; knife-edge hovers are great!). The builtup Depron fuz is nice and stiff for motor/flying loads but crumples a bit when you 'dump' it (how else can you learn?). Other than the odd bit of 1/64" ply, bamboo skewers and copious amounts of foam-friendly cyno, it is fairly resilient.

I used 2mm Depron for the fuz and 3mm for the rest but 3mm all round will be fine. The wing has a hollow 3mm carbon spar for strength, and the tailplane is an all-moving affair pivoting on 2mm carbon through an ali tube. The carbon is usually a bit a of a loose fit so drip thin cyno on the carbon, allow to cure, sand smooth with fine sandpaper until you get a snug fit in a tube. The plans have some more details but I don't specify every component or how to make everything. Take a look at my larger Ultimate if you want more details on how to build models like this.

As usual you may build the model but may not profit from the design. Please send me photos of colourful designs and suggestions for improvements. Plans for the 197sqin version in various formats follow. Check the reference line and use a photocopier to adjust the size or drop me an email...

PDF plans for 'A4' paper (49kb)
PDF plans for 'Letter' paper (49kb)
Zipped DXF plans (30kb)

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