Graupner

Junior Sport Plus

Introduction

I wanted an electric glider so I could cheat when the slope lift had gone and when I did not want to have to carry all the equipment that goes with power flying.  I made some telephone calls to people that I thought would know what type of glider I would need and the name that kept popping up was Graupner Junior Sport Plus.  Some of my fellow club flyers had either bought the Junior Sport or had flown one belonging to someone else and did not have a bad word for it.  On returning from a day at the National, I had in my possession a Graupner Junior Sport Plus, electric motor with gearbox, folding propeller and battery.   Somewhere at home I had a speed controller and flied charger so I had all that I needed to get started.

 

The ModelJunior Sport Plus1.JPG (38849 bytes)

ARTF model for electric power with 6 or 7 NC cells for 4-channel RC the Junior Sport Plus is an updated version of the Junior Sport, the Plus version comes with ailerons. Graupner description of this model is, “the Junior Sport Plus offers excellent performance and outstanding spot-landing capabilities, and is thus ideal for the popular “Everyman” style of competition, as well as for long, relaxed flights at the weekend or on holiday’’.  I have to agree with them on the performance, as it surprised me.  What do you get for your money? Clear assembly instructions in German, English, French, Dutch and Italian.  A ready-made PERFEKT fuselage, lightweight wings that are fully sheeted in balsa and film-covered tail panels. Wings feature ailerons and pre-fitted aileron servo extension leads.  Vacuum-moulded canopy in carbon-look ABS, with retainer bar factory-fitted, die-cut and printed plywood panels, decal sheet, small parts and control linkage hardware.

 

Building

This should be assembling the model, as there is every little building to be done.  I am not going to go through the building instructions one at a time, e.g., stick part A to part B.  I am just going to tell you about the areas that gave me some concern.  Graupner recommend Stabilit express, UHU hard and UHU blitz.  Well I had not heard of any of these glues before and as it turns out UHU hard is basically baisa cement and UHU blitz is cyano.  Stadilit express is used a lot by the boat-building boys, as it is very good at bonding to plastic and can be purchased from most good model shops. 

Fuselage

There are only six parts to be glued into the fuselage; the wing bolt, nuts retaining plate, Battery/servo support, two outer bowden sleeve, tailplane bolt retainer and the fin/rudder.  The tailplane bolt, nut retainer can be a little bit tricky then you try to fit it dry but when the glue this applied and if you use the bolt to align it, it is much easier.  The plywood battery support also holds the servos for the elevator and rudder, which is glued into the fuselage. I positioned it so I had room to get at the back servo screws but when I came to balance the model, I had to add weight to the back end.  In hindsight, I would have installed it back further and I do not think it would have been a problem if I had not put the biggest electric power system they recommended for this model (speed gear 600) in.

Fitting the threaded coupler to inner bowden cable was a bit tricky and I had to use smaller cleaves.  I was a little disappointed to find only one outer bowden sleeve in the box when two were indicated on the parts list. There is no mention of the motor installation in the instructions but it does show it on the plan.  With the Graupner motor it is not difficult to fit, if the countersunk screw were actually in the box!

Wings

I was impressed with the wing panel in general but the only thing that I did not like was that there were marks on them from the cardboard packing inserts.  The covering is very good with no wrinkles or bubbles.  I have heard of some ARTF models where you have to put the iron over them when you take them out of the box.  The wings are flat when you take them out of the box and they look as if the wing has been creased but when you read the instructions you discover they have a dihedral break.  You have to cut through the covering on the top surface along the dihedral break, then you have to remove the jig strip inside the joint and iron down the film on the inside of the facings.  Glue the panels together with the correct amount of dihedral.  Fit the servos and covers and that is more or less it and then you have two wing panels.  I used a couple of Hitec HS101 servos in the wings and I had to open out the servo bay a little bit, but when the covers where put in place you cannot see any difference. When I fitted my two wing planes together using the wing joiner rod they were out of line by about 2mm.  In a short time I had a very good-looking model glider.  All that was left to do was to see how well it would fly.  If it flew as well as it looked I was going to be pleased.

Installing the RC system

With the servos in place I followed the measurements on the plane to set up the control surfaces movement.  The aileron/spoilers are the only control surface with a specified deflection measurement.  There is room in the fuselage to use a standard receiver and servos with no problems.  My RC 30amp speed control was installed, the Graupner speed gear 600 with a 12 x 10 folding propeller and Sanyo 7n 2000 flight battery.

Balancing

With the model fully rigged I could not get the balance point right, even with every thing pushed back as far as the servos would allow.  I was force to add weight to the back end, 40grams in total.  It goes against my principles so I will move the battery/servo support back one-day.

Test flight

Due to the typical English weather it sat in its box for two weeks, yes in its box, as the tailplane is removable the complete model can be transported and stored in its original packaging the packing inserts have to be removed to facilitate this.

The big day had arrived, I was sat having a cup of tea when the telephone rang, it was one of my club mates, informing me that the sun was out, there was very little wind at the flying field and that I had no more excuses.  So off to the field I went.  With the model assembled a range check was completed with and without the motor running, all was ok.  With the help of a club mate the model was checked once more for control, balance and launch into the wind.  By the time my club mate had let go of the model it was almost at flying speed, boy can he run!  The model climbed away a little bit too steep for my liking, and so two clicks of down trim were added.  In no time at all the model was at height to stop the motor, and the glide was slightly too fast, so the trim was put back to neutral.  Some flat turns were tried using rudder and aileron, the result was near perfect and the grin on my face was growing all the time.  The still was explored, no problem there as it just nodded.  Next it was put into a slight dive and with the elevator released to neutral it pulled out straight away.  I prefer my model to stay in the dive a little longer so I will move the centre of gravity back a little at a time until I am happy with it.  Time for other climb and try the spoilers.  With full spoilers out it needed just a little bit of down elevator to stop it nosing up.  With the battery only having had a couple of motor runs it was time to do some low passes for the camera.  It is not wise to start doing low passes with low battery power especially when using BEC speed controller.  It was time to gain some height and relax.  Before the second flight I did some programming, with full throttle I mix a very small amount of down elevator and with full spoilers.  I also enabled the Ailerons/Rudder coupling switch.  I think that when the centre of gravity is move back there will be no need to mix down elevator in.  My first flight lasted 25 minutes with the second lasting 33 minutes.  All the credit has to go to the model, as I could not find a thermal, even if it was to come up and tap me on the shoulder.

Conclusion

The Graupner Junior Sport Plus is a very easy model to build and fly.  It is responsive enough not to be boring, but on the other hand it will almost fly itself.  The wings appear to be a little on the flimsy side for my liking and they do not look as if they would take a lot of abuse, but only time will tell.  The quality of the kit is good, but I am still not convinced it is worth £136.  It is my first ARTF model so I might be a bit out of touch with the price of these types of models.

   

Specifications

Information

Model Information

R/C Function

Specification

Dislikes

Likes

Update

I have now flown this model a number of times and on average I am getting 35 to 40 minutes on 2000 flight battery, with no thermals insight.  The wings have taken the abuse very well and my first fears may have been unfounded.  I have since found that this model can also be purchased in Germany for around £85 just my luck!

 

Graupner Junior Sport Plus Review by Michael Terry