E-flite Diamante

The Diamante 25e was designed by Peter Goldsmith as a sport aerobatic model with a slight lean towards F3A pattern flying. With a broad section at its root, the wing is a one-piece affair spanning some 48” with a taper on both leading and trailing edges. Meanwhile, the 50” long fuselage, embellished with Chris Foss style fin and rudder, swept undercarriage and blistered cowl makes for a very attractive bird.

Since the model is designed around one of E-flite’s Power motors (the 25 or 32) I was confident that the package would be good, especially when married to an E-flite 60 amp switching ESC and a 3300 – 3700mAh 3s Li-Po. On the radio side the manual suggests the use of four JR Sport servos which, to be honest, neither I or MacGregor Industries (JR UK distributor) had come across. Clearly a US specification was being quoted here, so instead, I fitted Hitec HS82MGs, these being identical in performance to the recommended JR units, if a little lighter and smaller.

Assembly of this model is a real non-event, assisted no end by a superb instruction manual that features a foolproof step-by-step approach to the whole thing. Truth is, there’s little to report here save my initial concern over the strength of the fuselage where the two-piece undercarriage legs attach, concerns that were realised during flight testing. In hindsight, then, I’d strongly advise builders to reinforce the undercarriage in this area by fitting an extra ply plate over the top of the existing item.

Since the model’s designed around the Power 25 motor it seemed rude to fit anything else, the unit slipping straight in and aligning perfectly with the pre-installed captive nut holes in the motor mount. A 13 x 6.5” APC-E was my chosen propeller, this coupled to an Irvine aluminium backed spinner in light of the supplied item being grossly out of balance.

Early flights were made using the recommended 3700mAh 3s pack, followed by further testing with a lighter 3300mAh job. Likewise, I experimented with propellers ranging from 12 x 8” through to 14 x 7”, but eventually settled on a 12 x 8, which appears to suit the model’s pattern aerobatic remit and through which the motor generates a healthy 318 watts, drawing 31amps.

Take off on the maiden flight proved delightful, with good accurate ground handling (no torque swing) and plenty of power in reserve. Once airborne I had to add several clicks of down elevator to stem the climb, something that was later adjusted as a by-product of moving the battery forward to cure the twitchy elevator at the suggested C of G setting.

Having landed to make the adjustments I also added a touch more elevator expo’ and leaned out the expo’ on aileron.

Tweaks made the second take-off was much better, to the point that I was able to remove most of the previous elevator trim.

To aerobatics, then, where personally I found the roll rate on the standard setting a little slow. Mind you, I like plenty of aileron throw, so you may find otherwise. The elevator is fine on standard settings, yet 3D style manoeuvres will need full rates (and some!). Mind you, even then the Diamante struggles and often refuses to co-operate which, given the type of model, is hardly surprising. Not to worry, knife-edge flight is a doddle thanks to the large rudder, knife-edge loops being eminently possible, along with all other power demanding vertical manoeuvres.

I wouldn’t call the Diamante tricky to fly, yet the thin, low drag wing means she can be tetchy at slow speed and will drop a wing if provoked. At the other end of the flight envelope, the power from the 25 motor is superb, providing a satisfying turn of speed when required.

All in all, the Diamante is a very stable flyer and, as you’ll have surmised, smooth pattern aerobatics are what this one does best, undoubtedly assisted by a slight excess of weight compared to other models of this size. Not always such a bad thing when flying in a wind! Homecomings are straightforward although the Diamante isn’t a cut and glide machine, so a reasonable landing speed must be maintained to ensure the model doesn’t drop a wing and / or damage that rather weak undercarriage mount.

Overall, a cracking little aeroplane. At first glance the Diamante may seem rather bland but don’t be deceived. There’s performance in this package, and in flying an aeroplane that cuts like an arrow and goes where you put it, oodles of pleasure to be had.

TWO MONTHS ON….

Actually, it’s about 6-months on as I’d flown the Diamante extensively by the time the review was published (RCM&E Aug ’09). 

Although I fly a wide variety of models, now I come to think, it’s the Diamante that I’ve clocked up most airtime with this summer –  a combination of the model’s ability to cope with breezy conditions (a slippery shape and higher all-up weight than you’d expect for an electric aerobat of this size) and very fine flying qualities. Undercarriage aside, it has proven to be strong enough to cope with the rigours of a grassy patch and all the high-G manouevers I can think of. In this respect it seems particularly adept at rolling circles.

That’s all I can add really, she’s a fine aeroplane.  

DATAFILE

Name:   E-flite Diamante 25e
Model type: Low wing F3A style aerobat
Manufactured by:  E-flite
UK distributor:   Horizon Hobby UK, Tel. 01279 641097, www.horizonhobby.co.uk
RRP:   £112.59
Wingspan:  48” (1200mm)
Fuselage length:   50” (1250mm)
Wing area:   485sq. in. (31.3 sq. dm)
All-up weight:   3.6 – 4.2 lb (1.6 – 1.9kg)
Functions (servos):   Rudder (1); elevator (1); throttle (0); ailerons (2)
Rec’d powertrain:   E-flite Power 25 outrunner; E-flite 60 amp Pro ESC; 12 x 8” APC-E prop; 3300 – 3700mAh 3s Li-Po battery