GUANLI Me109 Review

Summary:

Wingspan: 900mm
AUW (as built): 470g (16.8 oz)
Power Setup: 3s 1250mAh, 200w TP 2409-12T Outrunner, ASSAN 25A ESC.
Avionics: Guanli 36MHz RX, 3 x 9g Guanli Servos

Pros:

• Great looks.
• Fast assembly with neat features and handy included tools.
• Surprisingly good hardware.
• Flys well provided you keep the energy up.
  

Cons:

• Tricky flying envelope (see scale note above).
• Legacy of NiMH design (battery compartment to thin, and gearbox setup).

Introduction:

When Richard Wood (Woodsy) from AussiEFlight announced he was looking for people to review a new range of small foam warbirds he was planning to import I thought I may as well jump in.

I'm a big fan of foam warbirds - a little bit of history come to life. I've had a great deal of success with my GWS Zero, and even though the Ultrafly P51 wasn't half the plane the Zero was, I've still found a niche to fly it in.

The plane that was coming to me was the GUANLI Me109 (aka Bf109). Along with the plane itself was a full avionics pack including servos, RX, ESC and brushless gearbox/motor.

Before we get into the review it's probably worth going over what the review is about. The review's purpose was to let Woodsy get some honest feedback about this new range of models. As such you may be surprised about the candor of this review. Don't take it as a bad sign about AussiEFlight -the entire purpose of this exercise from Woodsy's perspective is to make sure he doesn't send a pup to any of his customers.

Build:

I'm going to spare you the box photo - the plane was well packed and arrived without a mark.

At first look the standard of completion was very high. The fuselage comes fully assembled and all control surfaces are pre-hinged and secured. That was great news for a fast build. The foam is well finished and painted. As scale models go, it quite looked the part.

Construction is foam around a central ply skeleton which is common to many of these foamies. Seems like a smart way to save some weight, and add some strength to the model.

If you look at the photo on the right you can see the two servo holes for the elevator and rudder servo at the right of the photo. From taking a look you may be able to see the small notch, which provides a nice convenient place for the servo lead to run.

This photo of the wing servo hold shows the same slot. It may not seem like a big thing, but it shows a surprising amount of forethought for a budget Chinese model.

Before installing the supplied servos I tested them all on the bench with a flight pack. Always a good idea with new servos - test before installation.

Another surprising feature was this neat little bag of tools, including even a roll of sticky tape (uneeded I might add) and magnetised screw driver.
This might seem like strange little things to stress but I was impressed - and optimistic. These little things showed a lot more thought than I would have expected.

As I started putting the model together I was impressed by the quality of fit. For example - how well the wing fit the wing saddle on the fuselage. And how well the battery cover/cockpit fit the fuselage.

Hardware with the model was surprisingly high quality too. Collars for the wheels, even a nice wide tail wheel.

The plane uses a single servo for the aileron. The last model I built with this kind of setup was the GWS Zero. For that one I had to put the 90 degree bends in the wire so that I could "trim" the ailerons to line up with each other.

No such problem with this plane - it includes threaded rods.

The one thing I did add to the build was some quick link connectors for the rudder and elevator horns. Seemed a shame not to use them when so much effort had gone into making the build very quick and slick otherwise.

Power System
Like lots of little foamies the GUANLI still seem to be obsessed with provide a motor stick setup built around the idea of using a gearbox. In an age where cheap outrunners are the fastest and most reliable way to power park flyers the throwback to NiMH/Brushed motor days is, to be honest, unwelcome.

However, Woodsy provided a little brushless inrunner gearbox rig for the plane. This seemed like the perfect solution, and with the plane itself he was seeking feedback.

Most motors are going to need some extension leads made up so that the motor leads can reach the battery compartment. I used some speaker wire for mine.

The gearbox was a 5.33:1 reduction, and the included props with the model were 10x8 slow flyer props. To be honest - a 10x8 prop on this plane would have been a mission - the undercarriage aren't that long - getting the plane to even rotate without prop striking would be a challenge.

Once again - this throwback to the NiMH stuff is a bit unwelcome.

Okay - so static testing the motor pulled about 15A with the included prop on a 3s - for about 15 seconds, and then began the tail of woe. When the prop spun the prop shaft shifted forwards just a little, which meant that the engine cog was only making contact with about a quarter of the prop cog. The result was that the metal engine cog stripped the plastic prop cog very quickly.

I've seen this exact problem on a mate's brushless gearbox motor (that came as part of an RTF plane). The problem is these cheap brushed speed 400 gearboxes are just not up to handling the power put out by a brushless motor. My mate's plane lost power in flight, and spun in (of course it sounds like it is working, and the prop is spinning, but you aren't actually getting any power).

So, I adjusted the motor cog, and spun up again this time making sure that the remaining 3/4 of the prop cog's teeth was in good contact. It took a little longer - maybe 45 seconds this time, but once again the prop cog was stripped.

Now - a static load test is the most demanding environment for the gearbox. There is no potential to unload, but nevertheless, the gearbox really should have stood up to more punishment than that. I would predict any plane running this setup on 3s can probably expect less than 10 flights before losing power in flight..., which won't be fun.

So, I decided to take a different tack and install simple, reliable brushless outrunner. Of course, the biggest problem here is that the motor mount is really built for a gearbox. I ordered a Towerpro 2409-12T (200W, 1600kv) for the plane. When it arrived I mounted it "high style" on the gearbox mount and then cut away the excess so that the gearbox could fit inside the nose.

Of course, because the plane is designed for the gearbox, even though the high mount of the outrunner puts the prop shaft in the right alignment, there is still an issue with the motor sticking out to far.

A little bit of dremmel surgery got the engine stick cut down, and enough foam cleared up to allow the motor to be mounted to emerge approximately flush from the end of the nose.

With the motor mounted successfully it was time to turn to power options. Once again, the lack of design work since the NiMH days left limited choices. The battery compartment is not very high. While there are plenty of 3s battery packs that will fit the space, none of them are the $25 type. For example, a 3s 1200Flightpower will fit the space quite happily - but it will cost more than the rest of the plane combined.

I have a 3s 1250mAh Multiplex battery that is quite thin that I use with the GWS Zero. When I checked her with the Multiplex battery installed she was perfectly balanced.

Flying

With the plane and power system sorted it was time for the test flight.

I lined her up with my other warbirds for a bit of a group photo. I'd bought my other warbirds to the field so I could fly them all back to back, so as to get an immediate comparision between them.

It was quite a windy day but I was confident the sleek lines of the me109 would handle it okay, and after giving both the zero and the mustang a go, I opened the throttle on the Me109.

Apart from need about 3 clicks of up trim she flew almost dead straight from take off, which is always a nice sign for a straight aircraft.

Having flown all 3 of my warbirds back to back I did get a sense of her very quickly.

Comparing her to my floaty/aerobatic GWS Zero (smaller wing span, almost exactly the same weight), and my porky fly on the wing Mustang the Me109 was, surprisingly, much more like the Mustang than the Zero.

She is certainly a capable flyer, but she demands your attention, and has quite a nasty tip stall. It is also possible, unless you are careful or running at WOT, to put her into a spin in a high banked corner quite easily if you aren't careful with the elevator.

This probably isn't a particularly good starter warbird - her small wing span means she lacks effeiciency and she is twitchy, and her typical warbird cut means she needs to be flown with some care, but I'm confident she will be a lot of fun.

Well - here's the youtube of the maiden video:



Avionics:

I haven't had any problems with the provided servos. They seem to be doing their job well. The Guanli RX hasn't been super solid. A few twitches in flights since the initial maiden have caused a little concern.

Conclusion:

This is a neat little plane, cheap, and fast to build. It flys like a warbird - it flys nicely on the wing, but it is unforgiving and has a real tip stall. Keep the energy up and learn how to fly her and you will have a lot of fun.

The lack of modernisation of the design (which is still built for NiMH) is a bit of a shame, although it can all be modded around without too much difficulty.