Some of you may be aware that I have been flying a 40 size Kyosho Spitfire in all the scale competitions this year. You might also know that I have converted the Spit to electric, as can be seen in an article in the 2006 news on this site. This is the first electric to fly in the competitions to anyone's recollection and I am proud to say that the Spit managed 2nd and third in them all and if not for a broken landing gear, it would have been first in one. I normally fly my Goldberg OS91 powered Super Chipmunk, but I wanted to show how far electrics have come.
Well, what you don't know is that I have taken it to the next level and bought an ESM 79 inch Stuka G.
The Stuka will also be electric and hopefully will have a sound system installed which will simulate the roar of the REAL engine and guns (and not cost me so many points for engine sound!). More on this later. It will also be converted to electric, using two twelve cell packs of A123 lithium ion cells in parallel to give 40 volts and 4.3 amps. I am hoping for an 8 to 10 minute flight from this which should get me comfortably through the scale schedule. I bought the Stuka from the very friendly and helpful guys at YT-International in the UK. They are the same company that sold me the parts for the Spitfire, Cub and Weston Cougar. The kit is a Chinese import from a company called ESM, which has been making ARTF's for some years. I was amazed to see the size of the box that it came in. It was huge! When I started to open the box, I found out why. There was an outer skin of cardboard wrapping an inner box made of almost 1 inch thick honeycomb cardboard. Inside this were all the bits of the plane neatly packed in foam and then bagged in plastic and then hot glued to cardboard dividers and box sections. Nothing was going to move in that box and it accounted for way over half the weight of the package. Needless to say, there was not a scratch on any part.


As you can see from the pictures, there are quite a lot of parts. Lots of screws, hinges and little fiddly bits that are always fun to mess with. The quality of the moulded parts is superb. All of the markings and panel lines have been done in the mould, so there is nothing for you to paint or add. Well if you are as big a kid as I am (and lets face it, most of you are :-) The first thing you do after unpacking and un-bagging all the bits, is to temporarily put the cowl and canopy on the fuse to see what it looks like.

The next thing is to put the wings together to see what they look like. Then it is those big 37 mm flack guns that the G model used to wipe out tanks. They called it the Panzerknacker (Tank Smasher) and Panzerjaeger (Tank Hunter)!


Now that the important part is done, it is time to have a look at the instructions. These consist of a clearly illustrated fifteen page A4 sized booklet and one A4 page for the guns. They seem fairly straight forward and I don't see any problems.....yet!
That ends part one of the review. Part two will take a while as I am still waiting for some gear to arrive in the post.

Well, I decided to start on the wing while I was waiting for the other bits. This is where I hit my first snag. Half the holes drilled in the ailerons and flaps to accept the Robart pin hinges were drilled rather crooked or in the wrong place! It seems like it must have been a Friday at the factory or something. To fix this, I filled the holes that were in the wrong place and then re-drilled them. The crooked holes got the file treatment to straighten them. I hope that filling up the filed out space with 30 minute epoxy will be good enough to hold the hinges in.

The wing comes in three pieces and is glued together where the wings bend up at each side. There is a plywood joiner for each side. The joiner is very strong and I am sure it will not break, but I decided to add a dowel near the trailing edge to give it a bit of extra strength, (To be sure. To be sure)

Everything went well here so I decided to cut the holes for the speakers. These went in the centre section of the wing facing down. There was about six inches between each rib, so there was enough room for a four inch speaker. I have to say, cutting four inch holes in a brand new 78 inch wing was a bit worrisome. Two deep breaths and away I went with the dremel. It turned out well and the speakers fit perfectly. These speakers are made with neodym magnets and are very light. They are supplied by www.aerosoundrc.com. On the bottom left you can see the sound system, well, you can see the two channel 40 watt amp, but the tiny sound module is under it and out of site

The next thing, I had a look at was the tail section. Well there were another couple of surprises waiting there for me. First, I put the two halves of the horizontal stab together and on to the empennage. These bits, as you know, should fit flat up against the plane so you can glue them tight. They Don't! Note the gap between the stab and the table on the right. There is about a 3 mm gap at the back of both stab halves. After a quick email to Martin at YT, we decided it was best to replace the stab halves. The problem was, when the new stab arrived, it was off as well. This time it was only a fraction and was corrected by bending the joining tube. I am going to follow the same procedure as with the wing and install a pin near the trailing edge on the same line with the joining tube. (To be sure. To be sure. To be sure.)

After that, I tried the elevator push rods. These are made up of an outer sleeve and an inner rod made of fibreglass. They were very tight and hard to move. The reason for this, I discovered, is that the sleeves were bent in an arc from the left elevator half to the left servo and the same for the right side. Imagine the line the rod has to take when it exits the fuse, going to the elevator control horn. They had the rod curving back to the servo on the same side. This was too much bending to let the rod move so, I broke the sleeves free and re-routed the left elevator rod to the right servo and right elevator to the left servo. This was enough to greatly decrease the friction in the sleeve and allow the rod to move.

The next thing I found is that A few small bits, including the blocks that you need to mount the rudder are missing. This is not a big deal since it was easy to make new ones and the rest I had in the workshop, but it is irritating when you just want to put the kit together and not re-work it. So far I am still very happy with this kit. It is a really good looking plane despite the few mess ups in the factory. I will remain happy as long as there are not too many more mess ups!

Here are the exhaust stacks and the gun flasher lights that I made up. Each muzzle holds 4 1 watt Luxian star LED's that should be seen from a long way off. The gun is sitting on top of one of the A123 lithium batteries that will be used to power the plane.

I had to take a break from working on it for the last few months, but have started again now. The wing is nearly finished after having all the electrics installed. There is a lot of wiring in the wing with four servos, two speakers, gun flashers, gun sound, engine sound, power for the amplifier and the battery to power it all. (I hope this thing gets off the ground!)
This is the flasher circuit board for the guns.

The servos are attached to a small piece of ply and then the ply is screwed to the wing with the servo inside the wing. This is about the easiest method of attaching wing servos that I have seen.

Despite the generally good quality of this kit, there are still a few minor annoyances, like the missing landing gear hold down straps, which I had to make and the bad positioning of the wood blocks on the inside of the wheel pants that the straps get screwed to. It seems that the model was designed well but the person that finished it after it was out of the mould, didn't care that much. Fortunately there were not that many parts he/she could mess up so I am still happy. After testing the cannons with the flashing lights and sound, the excitement makes me forget about any shortcomings.

If you are looking for a good place to buy lithium batteries, you should check out
www.desire-battery.com
They are manufacturers and can give you the best prices you will get anywhere.
Just email Kerry at
kerry@desire-battery.com

Well, the building is done and I am now waiting for the weekend for the test flight. I just finished last night and I want to write this now so I don't forget anything. ( The real reason is so I don't have to start cleaning up the mess I have made during the build. )



A lot has been done since the last update. The horizontal stab and stab supports were installed. This worked out well. If you remember, the joining tubes were not installed straight, so the stab halves did not match up with the fuse sides. After contacting Martin at YT International, I was sent a new stab, but on checking this, I found it to be a slight bit off as well. It was not too bad though so I bent the tube a small bit and that fixed the problem. I also installed a small pin at the trailing edge of the stab that continues through the fuse to make sure the halves don't come apart.



The elevator halves were easy enough to install once I spent an age making sure they were going to work after they were glued in. I spend too much time thinking about what I am going to do, but that is because there were times when I just ploughed ahead on things and then realized that there was a better way to do it ( or it doesn't work) after the glue was dry. That's when I use all the nice words I learned in the army.



Gluing the rudder was a bit of a pain, because the hinges don't go all the way in to the wood in the vertical stab. This is because they are hidden hinges and the joint of the hinge has to be inside the rudder. To support and retain the half of the hinge in the fin you have to make up small half disk like pieces of wood that get glued to the fin post and the hinge goes through and is glued to this and the fin post. Remember, these are Robart pin hinges. You also have to figure out how far to have the hinge line so the rudder will move far enough without binding on the bits of the fin that hide the hinges. Needless to say, I took a few days to study this and I am not sure even now that I have it as good as it could have been.



The tail wheel was a bit of a pain as well. It attached to the rudder via a torque arm with two screws and a bit of glue. The arm was only about ¾ inch long and the rudder was thin fiberglass where the screws went, so you know that would not last long. I decided to cut the bottom of the rudder and install a tube that fit the torque arm nicely. Leaving the arm free to twist in the tube kept it from binding. It seems to work, but time will tell.



Here you can see the AXI 5330/24 and the Phoenix 110HV speed controller.



Next it was the control linkages. I decided for two reasons to move the rudder servo all the way back under the horizontal stab. The first was that I thought I might have to put a battery where the pull-pull wires were to get the CG right. And second, I thought it would be easier than installing the wires. As it turned out, the CG was fine with both 6000 mah batteries as far forward as they could go. I decided to use ball links for the attachments on the rudder and elevator as these provided a bit of twisting movement without binding. This was necessary because of the angle the pushrods exited the fuse.



The battery compartment is in the nose of the plane and is made by hot gluing pieces of Styrofoam in to the shape of the batteries. A piece of epp foam wedged in between the batteries and the servo tray keeps the batteries in place.



The receiver is mounted inside the gunner. There is only a 2 inch antenna on the 2.4 gHz XPS system I am using so it fit nicely with just the part where you plug in the wires sticking out. I may cover this in the future, but for now it will do.



The receiver battery is a 3 cell 2250 mah lipo connected to a 5 amp ubec. The ubec brings the voltage down to 5 volts. The battery is monitored by a circuit that I made myself. It has 4 leds that come on as the pack voltage reaches 3.3 , 3.2, 3.1, and 3.0 volts per cell. This monitor works while the rx is on so the pack is under load and the leds show the true condition of the pack.



With everything put together, the empty weight ( without fuel, in this case the batteries ) was 14 pounds. This gave me a bit of a shock, since I was planning to use 4 pounds of A123 batteries. That would have made the total weight 18 pounds with a wing loading of 42 oz/sq.foot! So, I decided to use standard lithium batteries instead. This saved one pound and a bit which brought the wing loading to 39 oz. When you take off the weight for ethanol, you come up with 37 oz. This is still high, but I am told that it is not too high for a war bird. I know I will have to keep the speed up on landing and takeoff. I hope approach speed is under warp 9!



I ran the motor in the waiting room of my office last night. Try that with an IC motor! The power was breath taking and it blew the curtains and cushions all over the place.

I have to say, I am a bit nervous about flying this bird. The wing loading is high and I am planning for a great flight while preparing for the worst. If it is a good flight I will be over the moon, but if not, I will plan to put all the bits that are still working in a model with a larger wingspan.

Wish me luck!

YES, it was COLD!!!



Well, I had every intention of just taxi testing the Stuka today. After all, it was blowing a gale (almost) and was very gusty. Met Eireann described it as "blustery" and I think they hit the nail on the head. Neil Agnew was the only one hardy enough to join me in trying to freeze our backsides off.

Assembly on the field was quite easy and straight forward, thanks to Tim Costello's nifty stand. Even in the high wind there was no trouble and I can recommend it highly.

The next thing to get out of the way was the range check. With the XPS gear the check goes as follows: Remove antenna from tx.

Turn on tx and rx.

Hold button on tx to lower power to 10 milliwatt.

Walk 50 feet away and do a complete circle around the plane while making sure no control is lost. I varied the procedure here by having Neil spin the plane while I stood still.

Walk away from the plane with the low power button pushed until control begins to be lost then walk the same distance again to make sure there is no control. Once there re-install the antenna and make sure control comes back (button still pushed).

The last bit found me out of the gate and almost to the road before I lost control!

Replacing the antenna brings back full control and releasing the button brings the power up to 100 milliwatts. The next thing we did was take a few pictures, you know, for proof just in case :-)

That done, I taxied it out to the runway. One of the things I was worried about was the small amount of control movement. The rudder only has 20 mm each side. Flaps have 30 mm. Elevator only has 15mm and ailerons have 20mm. Well I didn't need to worry. The plane taxied just fine, so I started a medium speed run down the runway. This seemed to go just fine, so I tried one a bit faster. This time I brought the tail wheel off the ground and even got the mains up a few inches before shutting it down. I then taxied back and said to Neil; "I think I will fly it". Now that I look back on it, Neil had a "ARE YOU MAD" look on his face, but I didn't really notice it then. I then asked him if he thought I should fly it, but I didn't hear his answer because I had already decided to fly it by then and my ears were switched off along with my brain and many other parts of my body. All I could do now was concentrate on not needing a body bag to bring my Stuka home.

So I gradually increased throttle. Roll down the runway. A bit of a push was needed to get the tail wheel up so the plane didn't take off before enough speed was gained. "OH CRAPP!" The control movement was plenty" The extra few millimetres I gave it were not necessary and combined with the very gusty conditions, made it worse. Not to worry though, I managed to get it up and away. It was very twitchy to fly, because there was way too much movement on the elevator and ailerons and even with expo, it made for a bumpy ride. Also, every time I turned, the pitch would increase considerably. I think this was due to me pulling back a bit and the elevator being too sensitive.

The climb out was ok but a bit steep. Then the turn to downwind and "zoom" , it was gone with the wind (BIG wind) and I had to turn before I had chance to think. It got a bit far away and I almost lost orientation in the turn when the high aileron movement made the wings bank too fast. I managed to complete the turn and level off for a much slower upwind pass. This is when I noticed the sound of a full size plane coming from the general direction of my Stuka. I stopped shaking so much then and began to smile, because the sound was coming FROM my Stuka. This has to be the best thing to happen to electric planes since lipos. The sound is very realistic and I can't wait for a calmer day to do some low fast passes with engine roaring and guns blazing.

I only did two or three circuits and decided it was time to land. I was very nervous about this as you can guess, since the elements and the controls were ganging up on me to try to get the plane in that body bag. I was still at the end of the runway in the same position as when I took off and in spite of Neil telling me several times to move to the middle of the runway (ears still closed) my feet were rooted to the spot. This caused me to forget the wind direction and the runway I was supposed to land on and I made an approach on the same line I was doing the circuits on. By the time I realized my mistake, the plane was half way down the runway and just starting over the high grass. With "Got to get down" planted firmly in my mind, I got hit by a big gust that picked the plane up and over a bit. I was able to mostly regain control, but it bounced in from about a foot and a half and then nosed over. It wasn't going too fast by the time it was on the ground so the nose up only dislocated the barrel on one of the guns. The landing gear was bent and one of the wheel pants was cracked where it was glued together. I will have it fixed and ready to go in about an hour.

As Neil said, "there are not a lot of planes that would have flown in that wind" and I can tell you, I am not going to try it again! The reason I did is because I thought it would be safer to have a big headwind for landing since the weight of the plane might cause a high stall speed. I don't think it was necessary. The flaps slowed it down and even stabilized it a bit and if I was lined up with the runway, I might have had a good landing. (Don't laugh Neil!)

Here are a few pictures. There are two that look the same, but one has the guns firing and the other doesn't. They look better in real life and of course they sound better too.



This was quite a big project for an ARTF, but I have to say I have enjoyed it tremendously. There were a few bits and pieces that had to be worked around, but despite that, it was a well made kit and boy, does it look cool! I can recommend it to all intermediate to advanced builders, but I don't think it is for beginners. I would also suggest that if anyone was going to build a large plane and use the same sound gear and power that I did that the plane should be at least 86 inch wingspan so you don't have to worry about 37 oz/sq.ft. wing loading. This would also give you the opportunity to install larger speakers, which will increase volume.

Don't forget, you can find this plane and a lot more fantastic ARTF's on the YT International website www.ytinternational.co.uk . Tell em I sent ya.

Bob Finley
IRL 3345