JP Pretty 1500 review
The JP Pretty 1500 is an electric powered rc glider manufactured by Green RC and distributed in the UK by JP Distribution. It's a 1500mm (59") wingspan ARTF (Almost Ready To Fly) glider of traditional balsa construction for the flying surfaces and a moulded GRP fuselage. Attractively finished in white and translucent blue, the Pretty 1500 is a good looking glider for anyone wanting something less than a 2 meter span model.
My decision to buy a Pretty 1500 was based on wanting something faster and more aerobatic than my ParkZone Radian Pro foam electric glider, but something that wasn't quite a 'hotliner' - the Pretty is more of a luke-warmliner!
Pretty 1500 - what's in the box?
The glider comes well packaged and JP Distribution does an excellent job of protecting against transit damage; past experience tells me how easily a balsa rc glider can be crushed en route by careless couriers but thankfully my Pretty arrived at the door unscathed.
Opening the box reveals the plastic bag wrapped components: GRP fuselage with brushless motor, ESC and folding prop already in place, two wing panels, tailplane and fin, instruction manual, a DVD and a small bag of hardware and other odds and ends. The following photos show the JP Pretty 1500 packaged up and then unboxed:
On first impressions the build quality is good and the finishing just as satisfactory. In true ARTF form there were a few wrinkles in the white covering on the wings and elevator but the translucent blue had remained taught throughout. What I have subsequently found is that the wrinkles aren't too easy to remove; my heat iron gets them out initially but they creep back after a short time.
The translucent blue shows off a neatly built balsa framework tailplane and fin (tail control surfaces are balsa sheet covered in white). The wing panels are traditionally constructed with 3/32" ribs and top and bottom sheeted back from the leading edge to the main spar. Lightening holes are in the trailing edge and wingtip pieces while the ailerons are stock T.E. section.
Inside the fuse there is a ply plate with pre-cut holes for elevator and rudder servos although my choice of servo (Etronix 9g) meant that I had to fabricate a secondary plate to sit on top of the installed one, because the Etronix servos are marginally smaller than the holes provided. I made the plate from 1/8" ply and glued it in place...
Receiver installation proved a bit more problematic, largely due to the fact that my choice of 3S 2150mAH Li-po battery pack meant that the pack had to sit as far back in the canopy area as possible to aid getting the CoG correct (the recommended pack is an 8 or 9 cell NiMH one but a 3S li-po works well).
My choice of Rx was the Spektrum AR600 and about the only place I could locate it was in front of the foremost former. I'm still not happy with this location and in time I will look at other options.
Incidentally, while the JP Pretty 1500 does come with a battery pack 'holder' it doesn't seem to be for this particular glider, or if it is then the designers must have had one too many beers before they thought of it! The holder is a ply plate with a two piece velcro strap attached but there's no logical way of mounting it in the canopy area, and besides which the strap is fitted lengthways and not sideways - the whole thing just isn't right. As a result I made up my own securing device - a velcro strap held in place by a 1/16" ply plate and copious amounts of 5-minute epoxy, plus a small block also epoxied in place to prevent the pack from sliding forward. The receiver does the job at the other end of the pack, with a small piece of foam between the two.
The supplied ESC (18A) can be stuck to the side of the fuselage, I secured mine with strong doubled sided tape.
With the 'difficult' stuff out the way it was time to sort out the control surfaces and tail assembly. Actually the method of tail assembly on the JP Pretty 1500 is simple and effective: two threaded metal rods come down from the bottom of the fin and locate through the tailplane and then through the fuselage, held in place by two small nuts underneath. It really does work well and there are two small strips of card provided to slide under one side of the tailplane if any levelling adjustment is needed; my Pretty needed one piece under the left side of the tail to square everything up when viewed from the front of the glider.
The control surfaces (rudder, elevator and ailerons) are supplied loose, for reasons best known to the manufacturers Green RC, and come with hinge slots already cut - generous in length, it has to be said. The hinges supplied are the CA variety, about my least favourite type, but that's just a personal preference thing. The instructional DVD shows the easy process of mating the control surface to its parent flying surface dry and then applying the CA along the hinge surface, through a fine nozzle on the glue bottle. The CA wicks in to the hinge and all is good.
As usual my experience differed slightly in that I didn't have a suitable thin nozzle for my bottle of CA, so all I could do was to put a small amount of adhesive on each hinge and slide everything in to place, frantically trying to line it all up before the CA set! It just about worked but one aileron didn't quite go to plan and I was left with a 3mm gap between aileron and wing. Very unsightly and possibly detrimental to the aileron's effectiveness in the air, so I sealed the gap on both ailerons with blue tape. Nobody will notice when my JP Pretty 1500 is a few hundred feet up....
Above: all control surfaces are prepared for CA hinging and need gluing in place.
With all control surfaces of the Pretty 1500 done the only thing left was the servo linkage to each surface.
For the size of glider the linkages supplied are rather on the heavy duty side, in my opinion, but I used them anyway. The metal clevises are a pain to get apart to locate on to the control horns, if you have any circlip pliers then they will do the job easily. As the photo further up the page shows, the clevises are secured by a small locking nut and a tapered spring adds to the security.
One word of warning here - the metal rods supplied for the servo linkages are heavier gauge than they need to be and your micro servo horn might not be wide enough to take the diameter hole required. Fortunately mine were (just) and drilling out the hole on the horn still left enough plastic on each side to be safe. A narrower servo horn will almost certainly mean a thinner gauge linkage will be required, or use a disc on the servo.
One thing I haven't yet mentioned is the wing locating pins; a short carbon rod protrudes from the leading edge of each wing panel to locate in to holes in the fuselage. The holes are already there but mine took a fair amount of opening up in order for the wing to locate properly. A small file did the job, the photo to the right shows just how bad the alignment was out the factory - compare the pre-drilled holes to the actual location of the rods (the black marker pen).
The JP Pretty 1500 flight test
Fortunately some decent spring weather was holding - blue sky and very warm with little wind, so down to the local school field I went.
As I put the Pretty together I realised that I'd forgotten to put the Watt meter on it beforehand but my earlier internet research indicated that my 2150mAh 3S Li-po pack would be within the ESC and motor limits, so long as I didn't run it flat out for too long. That was fine, I only needed some short WOT bursts to see how the climb rate was and assess its aerobatic qualities!
A hand launch saw the Pretty 1500 pull effortlessly skywards and I held a 60 degree (or so) climb until it was at a safe altitude before throttling back and flying some circuits to trim the glider. It was immediately evident that the CoG was too far forward and a dive test confirmed this. Subsequently I've added some lead to the tail end of the fuse (conveniently held in place by one of the tail securing nuts) and this has sorted the CoG nicely.
The speed of the JP Pretty 1500 isn't blisteringly fast but it's enough for me. Basic aerobatics are easily achieved although the axial roll rate is sluggish, in true powered glider fashion!
The other main test of course is the soaring abilities of the glider and here there is a definite issue. Even with the power fully off, the folding prop refuses to fold and instead windmills, which is very annoying indeed because the drag created by the windmilling blades doesn't do anything for the glide rate. I've unsuccessfully tried the rubber band trick and also glued two pieces of clear plastic to the spinner to push against the blades but to no effect - this is one stubborn folding prop! I think my solution is to get a better ESC with a brake function, I'll post the results when it happens. Update - yep, a new ESC with brake worked a treat!
While talking about the ESC, it was quite hot after a flight with more WOT time than usual. At the time of writing this page I still need to get the Watt meter on it, but I'm certain that when I get a brake-equipped ESC I'll up the amps at the same time, maybe a 25A one will be better.
I never managed to do a flight video, but here's one I found on YouTube...
JP Pretty 1500 final thoughts...
Well hopefully this page has given you an idea of how the JP Pretty 1500 electric glider is, and whether it's suitable for your needs.
Overall I'm pleased with the plane; the few assembly/installation issues I had were easily sorted with a bit of thought and a better ESC will almost certainly improve the flying experience, notably the soaring side of it anyway.
The two piece wing makes transportation easy and the construction seems robust enough, and the quality is certainly more than acceptable for an ARTF rc glider. All in all a very nice electric glider for anyone looking for something that will provide some relaxed flying with the odd burst of aerobatics.