Seagull Zero .75-.91 ARTF

Hi David

How's the build going? I'm just about to order one (ic power) and I've already decided that I'm going to use either the Lado or eFlite electric retracts depending on available funds!

Cheers

Tim

Hi Tim,

I had been meaning to update my post but circumstances have conspired against me. I have in fact completed the build (wow! an ARTF build in only 6 months!) but a combination of family illness and moving house have meant that the maiden flight still hasn't happened. In fact all my modeling stuff is piled up somewhere, awaiting delivery of my shed. So it might be a while yet.

Anyway, so far I would say the Zero is a 'mixed bag'. Some aspects of the model are excellent - the cowl and, particularly, the canopy are brilliant and the plywood framework to support the cowl is nicely made. I have no experience with retracts but the ones supplied look extremely robust to me- I wouldn't buy any others till you have had a look at them. I have strengthened up the mountings for the retracts with some extra hardwood blocks and it all seems pretty strong to me. Unfortunately the retract mounts as supplied do stick out of the wing somewhat which is a bit ugly.

It all fits together pretty well, although the steerable tailwheel was a problem - I would cut a slot in the plastic cowling at the rear of the fuselage to make room for the actuating arm. I didn't and regret it. The holes in the control surfaces for the control horns are not deep enough and have to be cut through almost to the covering on the other side.

Another point I couldn't fathom is the retract servo mounting arrangements. Although the instructions didn't say so, there is a choice of two arrangements - a central servo operating both retracts or a wing mounted servo for each retract. I didn't fancy the central servo arrangement as it would have meant setting up the retract servo every time the model is assembled (its a two piece wing). So I've gone for the separate servos in each wing. Unfortunately the servo mounts supplied are too small for most standard servos. I was able to find one (rather fast) servo that will fit (Hitec HS225), and I am using a 'servo slow' to slow them down.

My main warning to you though would be regarding the instructions - don't trust them! The distance they give from firewall to prop driver is plain wrong. Check it yourself before cutting anything (I can't give you the distance I used at the moment without disinterring the model from the mass of house moving junk). I also believe the centre of gravity they give is wrong. From memory they say it should be 95mm from the leading edge but that looks ridiculously far forward. Even with my 6S 5000mah Lipo as far forward as I can get it, I would still need a small church roof of lead in the nose to achieve it. I have run the model through a C of G calculator **LINK** and as a result set mine at about 112mm back from the leading edge (from memory). The calculator suggests it wouldn't fly at 95mm. Even for that I need a few ounces of lead on the motor mount.

The all up weight comes to around 10lb - I have a 1150 watt power set up.

I will tell you how I get on after the - eventual - maiden flight. Once I have disinterred the model I might even take some pictures!

David

Oh dear, think I did that wrong -here is the C of G calculator I used **LINK**

I'm determined to insert the link to the C of G calculator I used. Having read the instructions, here it is:

C of G calculator

Thanks for the reply, hope you're getting straight now. All good info, I should pick mine up this week and will try to do a build blog. Pics of yours would be great. It always amazes me that the manufacturer can get the C.G. so wrong, and this isn't the first time I've come across this. I know what you mean about the instructions! Ambiguous.

Cheers

Tim

Hi all,
Well I didn't get 'round to a build blog but she's finished.

There were a couple of niggles. The cowl measurements (firewall to prop driver) are wrong, the manual states 150mm but it's about 138 really. The flaps were a bit banana shaped from only being covered on one side, best to make new ones. The rudder control is iffy as it is driven by a torque rod from the steering tail wheel. I can't get it right using the push rod so I will convert it to pull pull. The spinner is rubbish, new one from Cosford show. The cowl is a bit long but OK and well made.
However, my greatest concern was the weight, or more specifically the wing loading. The structure in the tail is very substantial and while strong (don't use as much epoxy as the manual shows) makes it really tail heavy.
My engine of choice is the Saito FA115, there is a 6V flight battery on the engine box and a 4.8V battery over the fuel tank (for the flaps and retracts). The manual calls for a balance point of 95mm back from the leading edge and with such a short nose this would mean a chunk of ballast. Well David (above) reckoned that was too far forward and further research seemed to back this up. I ended up with 1/2 a pound of lead up front, mounted just behind the spinner on a metal bracket. This put the balance point at about 105mm (fingertip measured) and the AUW at 10lbs.
So it was with some trepidation that I lined her up into the wind on Sunday. The throws were checked (as per manual with 20% expo on elevator and ailerons) and the throttle opened. I elected to use the full length of the strip to make sure there was plenty of speed before rotation. It looked fantastic as the tail lifted, she bounced slightly on the mains and then climbed away. She was fast, responsive and looked every inch the deadly warbird. She tracked perfectly with only a couple of clicks of roll correction. After two circuits she was into low passes, rolls, big loops and all the usual warbird stuff.
Flap deployment (about 45 degrees) caused a slight drop of the nose and a marked slow down so I tried to test the stall. Even really slow and it just kept flying. A few more circuits and it was time to land. With the high wing loading I expected the landing to be speedy but the stall test made me happier. The first attempt was too hot so around again and with a longer final to bleed off the speed. She was super stable and touched down on the mains before the tail dropped. All went well untill the wing clipped the long grass (1 foot long!) and she twisted in. This snapped the starboard plastic retract block (far too weak) so I'm replacing them with Lado units.
This 'plane has gone from a worry to my favourite flier in one flight! We'll have to see how it stands up to more flights but judging by the quality of the build I've got every confidence. It looks good, flies great, a definite thumbs up, just needs a Corsair to chase!

Well I've just written a long account of my maiden flight but all the text has suddenly disappeared! Afraid I can't write it all again!

Anyway, to summarise, I had two flights, the first of which was quite good except for needing some up trim on the elevator and asking a friend standing next to me to do it. His efforts didn't work though, so I made a rather heavy landing, ending up bouncing into the very long grass around the field. It turned out he had used the throttle trim tab, not the elevator (and the moral is?) . No harm seemed to be done though, so I charged the battery and took off again, only to spend two minutes careering around the sky as the model shot up in the air every time I opened the throttle. I eventually lost control and the plane crashed, but without terminal damage.

I really don't understand what happened. It seemed like the motor had gained a lot of upthrust between the two flights, but on inspection the motor was undisturbed.

I'm now thinking of converting it to IC! I have no doubt it would fly perfectly with the electric set up but somehow electric doesn't seem right in a decent size warbird (I only built it electric because at the time I was building in the dining room of our flat - bringing home an oily model may just have been a step too far!) - and I think I can get up more enthusiasm for an IC model.

Before I do anything though, can you tell me Tim if your engine has any downthrust built in ? As far as I can see the Seagull electric motor mount has lots of right thrust, but no downthrust.

David

Hi David

sorry to hear about the rough flights. To answer the question my Saito 115 is bolted straight to the firewall with just the right thrust as built. Mine does climb a bit under power but not enough to matter. Where's your balance point? I only check with fingers but mine's about 105mm. Two more flights today and it's just stable, locked in and a breeze to land. There's a bit of pitch up with flaps but that fades as the speed drops off. Hope yours is fixable, I know I'd definitely have another if this goes in.

Hi Tim, yes it's perfectly fixable. I've decided to definitely convert it to IC - I have a Saito 91 looking for a home and for reasons I really can't explain I would be much more confident in an IC model.

The Cof G is currently set at 112mm back from the leading edge - measured pretty accurately. When I do the conversion I might move it forward a bit, but I doubt if that is the problem.

I'll probably start without any downthrust - the fact that yours flies well gives me a lot of confidence!

Thanks for the info, David

Hi David

I'm completely with you with ic, I love the whole engine thing, even the mess! Your 91 will fly it but make sure you've got good ground speed before rotating. Keep the take off angle low and when the airspeed is up fly it fast, it'll look great!

Hi all

I've got the Seagull Zero with OS 120 fs up front, still had to add weight to the mount. Ballanced mine as instructions and flies fine. Replaced retracts with E-flite electric (plug and play) works first time, also sprayed mine with a matt lacquer well worth the effort. A few small niggles with the kit, use pull pull on the rudder pushrod naff. Tail plane farings, had two left hand ones had to modify to fit. Also as stated fire wall to prop driver incorrect.

Apart from the above it flyes like a dream and looks the part in the air. Allways getting comments how good it looks and sounds.

ah well, in that case I'll definitely move the C of G forward a bit. IC conversion and various repairs almost finished. As usual turned out to be a bigger job than I thought!

Like the pic Tim do you have any more. What about some pics of yours as well David and Phil. I will definately be buying a Zero in the future. Just ordered a Hurricane though, that should be here any day now. Just spent 2 days cleaning my garage/workshop ready for the build. Pics to follow. Al

Sorry, no more pics of the Zero. Not flown it much lately, darn weather but I'd absolutely recommend it. Put a nice big motor up front (no cooling issues) and enjoy! Best advice is to think carefully about the rudder/tailwheel linkage, don't use the supplied method, it's rubbish!

Thanks for this thread. I have a Seagull Silence Twister ready to maiden fitted with two retract servos in the centre fuselage per the basic instructions. Having to rig these at the field was always going to be a fiddly problem and I was toying with the idea of fitting Eflite 60-120 retracts instead to ease rigging at the field and to free up space for a tidier r/x installation.

This thread has confirmed what I thought and I will be doing just that!

For once I am grateful that the poor weather has delayed the maiden flight!

Final thought: the comments re the poor instructions reasonated with me asI had similar issues with the instructions for the Twister...perhaps someone from Seagull will read and take note?

I agree. I've not used the Eflite ones, only the Lado retracts which are fantastic. Either way the reliability will be greatly improved.