Zulu ET

[Charlie Raley]

Hi again,

Thanks alot for the advice, it may be a arial conection as there is loose wire hopefuly i can solve it!!

I have one other question about the instilation of the electronics: when mounting my 1400KV motor is there any need to angle it or "pack it of" to one side/ up or down?

If someone could help me out it would be great then i will be ready to take to the skyies!!!

Regards

Charlie

[Charlie Raley]

Hi again,

Thanks alot for the advice, it may be a arial conection as there is loose wire and hopefuly i can solve it!!

I have one other question about the instilation of the electronics: when mounting my 1400KV motor is there any need to angle it or "pack it of" to one side/ up or down to compensate for the direction of spin ect...?

If someone could help me out it would be great then i will be ready to take to the skies!!!

Regards

Charlie

Edited By Charlie Raley on 11/09/2012 18:47:52

[Mike Robey]

Hi Charlie,

Lindsay says you can put a degree or so of right thrust if you want. In a previous post he said others had found that useful. Mine is almost ready to go and I am starting with zero thrust angle both horizontally and vertically. I planned to see how things went and adjust if needed.

Edited By Mike Robey on 13/09/2012 06:12:40

[Charlie Raley]

Thanks Mike

Ive decided to do the same, then i can add in thin washers to add an angle if there is any need!

I have finaly solved the mystery throttle case, the problem was a faulty lipo that hadnt charged so when conected to the ESC the voltage was to low and the BEC curcuit built in was not supplying enough volts to the reciever causing it to un bind and go haywire. A new Lipo and a reciever battery has solved the probem completley and i have just disconnected the power cable from the plug going from the ESC to the reciever.

[Mike Robey]

I just had my first flight with the Zulu and I would absolutely put in some down and right thrust. The swing to the left was not strong but it was there and mine wanted to climb everytime I put on power.

Good news is ailerons very responsive, elevator less so but still plenty there. In fact if you are used to more docile planes I would dial the ailerons down a bit. I like the response rate myself so its just what you are used to.

Bad news: I found mine want to tip on its nose on take off so I am moving my undercarriage forward.

Mine also has another problem. I have seen Lindsay's videos of both of his and they don't do what mine does so I have done something wrong in the build. What does it do? Well if you apply any amount of left rudder, my Zulu flicks over into a spin. Afterwards someone asked me if the same thing happened with right rudder and I honestly don't remember if I used right rudder. When it happened the first time it surprised me so I did another circuit and tried again just to be sure it was just the rudder input causing it. Did exactly the same thing.

I got her down okay by simply not touching the rudder and flying her bank and yank.

What I intend to do is to add the right and down thrust, move the cg further forward and see if that helps. I intend to wait for a still day where I can take off without using the rudder until she is 3 mistakes high and then see what happens.

I am worried I have screwed up the wings somehow. Can't see anything out of wack via eyeball. Some builders in my club think that sorting out the thrust angle and moving the CG forward will fix the problem but I am not so sure.

I really hope I can fix it because, for a tubby high winger, she is pretty agile and potentially a lot of fun.

Any thoughts or opinions appreciated

Edited By Mike Robey on 24/09/2012 05:07:58

[Lindsay Todd]

Rather unusual, move the CG further forward, a degree of downthrust and another of right should sort it out assuming now twists in the wing. Make sure you have wash in rather than wash out in the wing as that would provoke a tip stall. She is quite lively - was always intended as a sport model rather than a trainer but keep things docile and all should be good.

[Mike Robey]

Hi Lindsay,

I will do as you suggest but after what yopu said about washin/washout, I thought I needed a better way of checking if the wings were twisted. What I did was sticky tape four satay sticks (do people ever actually use these things for satay??) inboard and outboard of each wing. I reasoned that if the wing is straight then they should all be parallel. If not then the wing isn't straight.

As you can see from the photos below the right wing had a very slight twist which, when I printed the photo and used a protractor to measure the angle, meant the wing tip was approx. 1.5 degrees higher angle of attack then inboard.

I then used a heat gun and twisted the wing until the satay sticks line up parallel.

Hopefully that sorts it out.

The only thing that confuses me is wouldn't this cause a tip stall in the right wing? but it was the left wing that dropped. Either way still wrong so better fixed than not.

[Mike Robey]

Hi All,

Well I thought I'd let you all know what happened to my Zulu ET. I took Lindsay's advice and moved the cg 1 cm forward, added down and right thrust. As shown in my previous posting I also found a slight twist in the right wing and removed it. Finally I moved the undercarriage about 1 inch forward and swapped the two inch wheels I had on it for some 2.5 inch ones which were a much more appropriate size.

I spent the week in trepidation of what was going to happen and so when Sunday came around I was rather nervous. The forecast light easterlies turned out to be gusty 10 to 15 knot easterlies which didn't help. I had decided it was too windy but when the wind seemed to die down a bit I thought "Don't think about it just go for it!" so I powered up and headed for the flight line.

I took off (a very slight swing to the left) without touching the rudder and climbed up 3 mistakes high and then the moment to try the rudder had arrived. With baited breath I fed in left rudder and...

well the rudder behaved like a rudder! No violent flick/spins. From then on I threw her around like a mad thing. What a brilliant plane! Think Funcub but more sensitive ailerons and less sensitive elevator. Rolls are amazingly axial for a tubby looking high winger. Landing is pretty easy. You do have to keep a little power one because she is a bit draggy but otherwise is a real fine plane.

Thanks Lindsay for your advice and also for all those build photos in this thread. They were invaluable. Oh and also thanks for designing such a great plane. Below are two photos: the first is her after all the mods had been completed and the second is a frame lifted from some video of her first flight. I will be getting some better flight video later.

Charlie if you haven't done your maiden yet, check your wings are straight and move the CG a tad forward.

 

Edited By Mike Robey on 30/09/2012 15:25:34

[Lindsay Todd]

Don't you just luv happy endings

Linds

[Ron215]

Hi Mates

 

Built Zulu about 8 months ago and is still flying.

Edited By David Ashby - RCME on 14/10/2012 09:03:45

[Mike Robey]

Hi All,

I have done some youtube videos on the Zulu ET:

Intro and scary maiden flight:

Build video:

Flying video after everything sorted:

Enjoy.

[Radge]

Well done Mike! Great video, well flown, have a radgepat on the back!

[Dave W]

At long last my Zulu ET is in the air. I started building it soon after the plan was published but after reading some of the reports realised it was not for a beginner like me so it was put on the shelf while I got on with building more suitable models. With a lull in building the Zulu was completed.

Its first flight showed a marked determination on its part to swing left, as outlined in other reports. I had already built in a small amount of right thrust but this was obviously not enough. Someone else double checked that there were no warps creating problems so I then increased the right offset by quite a lot - to about 4 degrees. It now flies straight.

Its flight is quite interesting. Taking it on a gentle turn via ailerons it gets part way through the turn then suddenly rights itself before reverting to the bank and the turn. It is as if the dihedral (measures exactly as stated on the plan) is causing it to right itself every so often. As I say - interesting.

Assuming I don't crash it, I see many hours of fun flying ahead. Thanks Lindsay and RCM&E.

[Caveman]

So Dave W, I'm not the only Zulu ET Builder then!!!

I completed mine a few weeks ago - I built it in order to gain some experience prior to starting the mass build Tucano. As it turns out the Tucano is probably an easier build, but I wasn't to know.

I held off the maiden flight for a few weeks waiting for a decent, relatively wind-free day. One Saturday about a month ago seemed suitable so check the controls, range check, face into the wind and away we go. Well, it was totally uncontrollable and ended up meeting the ground in an undignified manner.

I took the bits home. Inspection showed surprisingly little damage other than the fuselage comprised two separate pieces. A couple of new parts, strengthening with a 1/4" spruce longerons on the centre line of each side, and new covering film soon had it back in one piece.

At this stage I checked the COG. It was suspected by one of our members/witnesses that the COG was too far rearwards. How right he was - I must have mis-measured when setting it up in the first place as it was about 10mm to far back. The addition of some additional lead now has it 15mm further forward.

I also took the opportunity to add about 3 degree of down-thrust and 3 degrees of right-thrust, and, added a hatch in front of the windscreen to avoid having to turn the plane over to change the battery.

10 days ago I tried again - the weather was a little windier than I would have liked, but opportunities are few and far between the way the weather's going at the moment. On the ground I found that full up elevator was needed to avoid the plane nosing over, but, once sufficient speed was gained it took off and headed for the skies.

I climbed to about 100ft and turned to the right to bring it downwind. I found the plane extremely reluctant to turn and needed to apply quite large amounts of rudder to bring the tail round and had a tendency to drop the nose. I flew around for a few minutes to get a feel for it and then landed - this also ended in a nose-over!

So, the conclusion is that it flies, but needs some sorting. I have since adjusted the undercarriage to move the wheels about 1 inch further forward as I'm sure they're too close to the COG. I'll slowly reduce the noseweight to move the COG further back as I'm thinking it's now too far forward, causing the dropping nose?

I've also wondered about adding differential to the ailerons to reduce the drag of the down-going aileron, which may help with the turns? Think the biggest help would be a windless day so the effects of gusting and turbulence can be minimised and the true character of the plane revealed.

Fingers crossed for some good weather......

Dave W, when you've had chance to fly a bit more I would be interested to hear your thoughts and any adjustments you make which will improved the model's performance.

Cheers GDB

ps. Pictures of my build are in my album.

[Mike Robey]

Hi Guys,

I found moving the CG 1cm forward helped a lot. I also moved the undercarriage forward to avoid the nose over issues. I started with zero degrees down and right thrust and got the swing on takeoff plus climbing when power was added. I followed Lindsay's advice and added down and right thrust. Unfortunately now I cannot remember how much but I don't get any swing on take off. It sounds like you have that part sorted now.

As far as the rudder is concerned, considering its small size(the rudder not the plane) I am amazed at how effective it is. When you apply rudder you will find the nose pitches down. All models do but the Zulu does this quite strongly. I also found the ailerons to be really sensitive. This seems to be in contrast with your experience. I did find that applying the rudder caused a strong roll (because of the dihedral). In flight this isn't an issue but it can get interesting when she lifts off just as you have input a dab of rudder to keep her straight.

If I was building another one I would not build in the dihedral. That would stop the rolling motion when applying rudder. I have often pondered the idea of mixing opposite aileron with the rudder to cancel out the rolling effect but never got around to trying.

I agree its no trainer. Its a very agile plane and I found it flies a lot like a warbird. It is tough as nails though. I bounced a landing quite badly and I did not realise the firewall had come loose. This became painfully obvious on the next flight when the poor thing became totally uncontrollable from the moment of lift off. My Zulu slammed into the ground so hard the aluminium undercarriage was bent straight! What totally amazed everyone who saw it was there was no other damage! I really thought it was a goner but all I had to do was bend the undercarriage back and replace the prop (and make sure the firewall was not going to ever come loose again!!).

Dave W the business of it suddenly straightening itself sounds strange. See if you can get someone to video your plane in flight or at least watch it and observe the control surface movements when this happens. I put a camera on my Funcub one day and noticed when watching the footage that my ailerons were constantly twitching. I had found it a little difficult to keep level that day but just thought it was me. Anyway the culprit was a dirty pot in my transmitter. Fixed that and the probelm vanished.

At any rate I hope both of you get your Zulu's sorted.

Edited By Mike Robey on 17/05/2013 16:57:20

[Peter Malkin 1]

We do I recently completed a very nice example of Zulu ET. Built according to plan, c.g correct, motor side thrust correct, no warps, control movements as recommended. My club C.F.I carried out the initial test flight, almost immediately on first turn left, model went into uncontrollable flick roll and crashed. Fortunately only a small amount of damage. Repaired, C.F.I again took control, same violent action again and model now complete write off. There is clearly a serious design problem with this model. Whilst it is stated that it could be used as a trainer it simply would not work in that role. I am not giving up on it however. I propose building a second example but this time will amend the fuselage to more conventional dimensions. Compared to other similar models, the fus is at least 150 mm too short! With this mod, we might finally get the thing to fly.

[Masher]

Very interesting! I  had exactly the same issue, spent weeks building the thing only for an instant write off. Unlike you, I did not give it a second chance 

 

[gangster]

41 minutes ago, Masher said:

Very interesting! I  had exactly the same issue, spent weeks building the thing only for an instant write off. Unlike you, I did not give it a second chance 

 

So it is not just me then. I have no desire to give it a second chance. My heart was never in that model