Thursday, September 2, 2010

Multiplex EasyStar Review: Part 2, Assembly and Maiden Flights

She has loads of character, graceful lines and means business!

In this Part 2 of my Multiplex EasyStar review, I'll trot through the assembly procedure and first flights.

Assembling the Multiplex EasyStar

It's been commented on by others that it's odd for a beginner's model to start off with soldering. I agree, but the motor needs leads.

Heatshrink tubing makes a neat job, even if I do say so myself. Note the black and red ink dots, which I marked once I'd hooked up the ESC and battery and figured out the correct polarity for electric connection and prop rotation. This is a brushed motor of course.

The motor and ESC being laid out. This is RC equipment from my old GWS SlowStick model, so I don't want to mess around with new cables and such. As I've said on this blog before, I'm not a real fan of CA glue. It has its uses, but is nasty stuff in my view. The instruction manual calls for CA glue and kicker. Yuck! I gave the motor mounting area a spray of kicker and put the glue on the motor parts before assembly. The smell of kicker makes me feel a little sick, so I decided not to use it again on this build. I'd rather wait for the CA to cure "au naturelle". I also used UHU Por in some places - which is really superb, foam-safe contact adhesive.

Since I'm going to leave awhile to let the glue set, I taped and banded up the fuselage sides. Here's the top view.

And here's the rear part of the fuselage banded and taped for setting. Masking tape is great - I love the stuff.

The receiver is fixed to the fuselage floor with velcro. If I had more wire slack, I'd move it forward, but it'll do for now.

The battery pushed forward completely to get the right CoG. I also needed to add 30g of ballast, because the battery is a lightweight NiMH job - 7xAAA cells, 800 mAh, ~110g. I'll upgrade it later.

Sorry for the blurred image. However, you should be able to see the canopy latching system above.

The servos are positioned in cutouts on each side of the fuselage. My servos are a bit smaller than the mountings, so I bodged some balsa support structure balsa. This will be covered up with stickers from the decal sheet later, so my aim was to be functional rather than pretty.

I've read in many places that the rudder authority is not great. Now, that rudder does look piddly to me. So, I decided to slot the edge and insert a small acetate tab, just to increase the size of the thing. "Acetate" is a flashy way of saying "packaging from my daughter's toy". Call me crazy, but I do save big bits of clear plastic from toy blister packs for model material. The stuff comes in handy all over the place.

Rudder horn fitted. The plastic tubing was CA'd in position in ready-made grooves on the fuselage sides. I set rudder throw to 10mm each way, as indicated in the manual.

A better view of the acetate rudder tab. I found it worthwhile to flex the rudder and elevator back and forth to loosen up the foam hinge. What an interesting way to create a hinge. It seems quite robust too.

The elevator horn is underneath the plane. The wire pushrods are gripped by the grub screw, which has a neat allen key head. You can adjust centering conveniently from here.

The prop had to be turned into pusher mode. Epoxy was used here as per instructions (minor thing, but it would have been preferable to have some sort of collet or removable clamp arrangement instead of gluing it to the prop shaft). In the background, you can see a wing root with a hole in it for taking the main spar, also a plastic - or possibly fibreglass? - tube.

This is the other wing, with the spar in it. I decided to glue the spar into one wing, simply because it means less faffing around when assembling in the field.

A photo of both wings and the spar. They fit together like jigsaw puzzle pieces. The foam has enough "give" in it to allow a "wiggle and push" fit.

Here are the wings being fitted together in the field. I have to say that it's a very clever and convenient wing joining mechanism.

All in all, assembling the EasyStar and kitting her with RC equipment was simple, helped by the manual being very clear with lots of pictures. She weighed in at 525g AUW with CoG as indicated in the manual, or possibly one or two mm behind it. Because of the small 7xAAA battery, she was over 100g lighter than the AUW indicated in the manual (680g with 6xAA pack).

Maiden Flight

This is a tale of "third time lucky".

I chose a great day for the maiden flight. Very light wind (6-8mph) and sunny. After checks, I turned up the throttle and threw her. The prop slipped forward off the spinner and freewheeled. I pushed forward to achieve a nose down attitude and then eased up to avoid a bad crash. I re-pressed the prop back in and tried again, but it slipped forward again. So, I came up with an inelegant field fix using a rubber band:

This was enough to hold the prop in place for the evening, so that I could fly.

Initially, she didn't fly straight, went into a turn and I was unable to straighten out from it! I was puzzled. Despite the acetate tab, perhaps the rudder authority was still insufficient? Lack of response to rudder input was especially apparent when flying downwind and trying to turn back upwind. The end result was a number of tip first landings. Thank goodness she's a tough plane! I adjusted rudder trim, she flew straighter, but turns were still a problem, unable to roll out of a turn once established. Pathetically, I managed to encourage her to climb using S turns upwind. That worked to allow a flight of 2-3 mins, with about a few seconds spent gliding and a reasonable landing. But by then, the puny battery was weak. So, I resorted to chucking her by hand. To my surprise, she had a fairly decent glide and good response with power off, especially to elevator inputs. Clearly, I had to try more rudder deflection.

First mods

So, overnight, I moved the control horn link position as close to the fin as it would go, in order to tease out max throw of the rudder (12mm instead of 10mm). Also, to fix the prop, I wound and CA'd a thread on to the prop spinner shaft to prevent it slipping forward:

Both changes had an immediate impact. The next day with a re-charged battery, she flew much better. There was a bit more power too - it could be that this battery needed a couple of discharges to liven it up, since it has being lying around for a while and/or the rubber band field fix had been added noticeable friction the previous day. Whatever the reason, I managed a flight of 7-8min, but still felt a lack of rudder control. Encouragingly, I enjoyed a few attempts at thermal soaring with the motor off and did a loop with no problem at all.

Next Mod: a Bigger and Better Rudder

That night, I decided to cut the fin at the rudder line and make a full length balsa rudder.

First, ruler and pen to mark off the cut line.

Using a scalpel, I cut along the line, leaving a tad of excess foam to allow me to bevel both sides of the fin into a V, again using a scalpel and finishing with a sanding block.

From medium 3/32" balsa, I cut a new full length rudder. The photo above shows the slot for taking the rudder horn. I decided to reinforce this by sticking a 1/32" cheek on the other side from the horn, cross grain, using waterproof wood glue. This would create a stiff, strong rudder.

I fashioned two hinges from roughened mylar. This kind of width was what I reckoned to be enough to create a smooth, easy to move hinge. I cut slits in the rudder to accommodate the hinges.

Before gluing in the hinges, I gave it two coats of sanding sealer and coloured two black stripes with permanent marker pen. The hinges were glued in with CA, and the horn with 5 min epoxy.

This is a view from the other side, showing the 1/32" balsa cross-grain reinforcing cheek.

Then, I cut slots in the fin (right on the apex of the V bevel) and CA'd in the hinges. Rigged up the wire pushrods.
It seemed to be better to put the grub screw underneath the horn, because this would reduce the bend on the pushrods and plastic housings. I made a tiny hole in the elevator hinge, to enable the allen key to reach the grub screw.
I adjusted the horn linkage position to give good throw, 12mm each way - using a steel ruler to measure it.

So, here we have it, the new full length, larger area rudder. It is light, stiff and moves smoothly, centreing well.

The following day, I flew her again, in a slightly stronger wind (9-10mph, with a few gusts). I used the same 800mAh battery, recharged overnight. The first flight was 10mins long with about 20% being thermal soaring. The second flight was about 3 mins, again borrowing climb from thermals. I packed up after that and at that stage, the battery still had a bit more oomph left in it. With more rudder, she was transformed. Quite enjoyable - I can now turn properly and roll easily back out of established turns! She flew a few loops and chandelles and we tried a half loop to inverted, which was a bit heart-thumping. It was fun to turn the motor off and soar. In the limited time I had that day, I thought she soared well, indicating lift clearly. She made one lovely climb in a thermal ending high up slightly downwind. I used the moter to get back upwind.

After initial teething troubles, she has ended up providing fresh excitement. I think she is just what I was after. I'm a little perplexed as to why Multiplex cannot give her a larger rudder, because it seems crystal clear to me that she needs one. They could also elimate the soldering step, but I suppose that allows users to choose their preferred motor connectors.

Also, she looks great from virtually all angles. I just love those upturned wing tips, curvy tail feathers and pusher prop.

And isn't that a gorgeous profile to look at in the sky? Love that torpedo shaped fuselage.

In summary, the Multiplex EasyStar is a convenient, stylish, neat and entertaining model. I'm hoping for many memorable flights in the future.


David said...

Great Post. Thanks for the info

Anonymous said...

Nice review! I might mount a bigger rudder as well on mine... thanks for your tips and photos!
John (NL)