My attempt at a SebArt Mytho S 50E

[Adrian Smith 1]

I fitted the firebox engine mount using the M4 bolts provided. This was done via the fuz interior which was fiddly, but not too difficult. I used thread lock to secure them. The mount is helpfully notched so the orientation is correct when fitted.

Edited By Adrian Smith 1 on 20/10/2016 19:30:02

[Adrian Smith 1]

The next job was to sold the motor to ESC connectors. I used 3.5mm gold plated bullet connectors here.

[Adrian Smith 1]

I thought with the engine box mounted I would just check the distance from firewall to cowl exit which is 76mm.

[Adrian Smith 1]

That done time to fit the motor. Despite what the January 2015 review might say, the motor mounting bolts are still too short and don't seem to have been replaced by the UK distributor (in this case Dumfries Models). I needed to raid the spares box for 4 M4 bolts 25mm in length to be safe. Another thing missing was for M4 nuts to finish the job off. Spares box again. I also used Nordlock washers for security.

The Hacker supplied prop hub was bolted to the motor with a dab of thread lock for security.

I refitted the cowl to see if all was ok.

Guess what? I need to fit another washer on the standoffs to give enough of the prop hub to protrude from the cowl. Not much in it but I need to be sure so I will redo the motor at the weekend and refit the cowl.

Edited By Adrian Smith 1 on 20/10/2016 19:42:04

[Rich too]

Posted by Adrian Smith 1 on 20/10/2016 19:31:22:

The next job was to sold the motor to ESC connectors. I used 3.5mm gold plated bullet connectors here.

I use a fireproof mat for soldering on!

[Rich too]

Posted by Adrian Smith 1 on 20/10/2016 19:39:56:

That done time to fit the motor. Despite what the January 2015 review might say, the motor mounting bolts are still too short and don't seem to have been replaced by the UK distributor (in this case Dumfries Models). I needed to raid the spares box for 4 M4 bolts 25mm in length to be safe. Another thing missing was for M4 nuts to finish the job off. Spares box again. I also used Nordlock washers for security.

The Hacker supplied prop hub was bolted to the motor with a dab of thread lock for security.

I refitted the cowl to see if all was ok.

Guess what? I need to fit another washer on the standoffs to give enough of the prop hub to protrude from the cowl. Not much in it but I need to be sure so I will redo the motor at the weekend and refit the cowl.

Edited By Adrian Smith 1 on 20/10/2016 19:42:04

One thing I did like about electric planes was the lack of having to cut up the cowl making the process much easier.  That motor looks huge! Is that equivalent to 50cc?

 

Edited By Rich2 on 20/10/2016 19:51:55

Edited By Rich2 on 20/10/2016 19:54:20

[Adrian Smith 1]

Rich, it is a bit deceptive the motor is equivalent to 70 four stroke glow so it is nowhere near 50cc. As you can see it is a big departure from my normal engine size!

[cymaz]

Nice build Adrian. However, will those little grub crews on the rudder servo be man enough to hold the cable ends?

I would worry about that

[Adrian Smith 1]

Well Cymaz I did wonder about that. However, in its favour is the grub screw sits on the threaded part of the cable coupler which gives it resistance against movement and with thread lock on the screw we will just have to see. All other pushrods have a flat filed on them where the grub screw sits & with thread lock of course. It is a very light aircraft and I suppose the fittings that come with it reflect that.

[Colin Carpenter]

My 4 Sebarts all use the same fittings . In a total of 260 flights they have never moved ! Colin

[Adrian Smith 1]

I took the motor off again today and found that to give a safe space between prop driver and cowl exit two extra washers per bolt were required over and above the stand offs. So back together and refit the cowl.

[Adrian Smith 1]

Next I fitted the ESC as per the manual under the motor box. I used some velcro to secure with a nylon tie cushioned with a thin piece of pipe insulation. I am hopeful that this method won't restrict the cooling required for the ESC.

[Adrian Smith 1]

I used a couple of rubber grommits (not supplied) to cushion the cowl screws.

The wheels and spats come next which was a bit of a fiddly job to get everything tightened up so as not to lose bits in flight. The U/C fairings where attached using silicone sealant as per manual and taped while drying.

That's the build done so next job is to set up the radio and working surfaces which I will do next week if flying weather doesn't present itself.

 

 

 

 

 

Edited By Adrian Smith 1 on 22/10/2016 18:07:43

[Rich too]

Blimey that was quick!

[Adrian Smith 1]

Yes Rich didn't seem to take too long. The fun part for me will be setting up the controls and a test motor run. I have a thought at the back of my mind that I have to reverse the throttle setting on my Futaba TX to get it working. In any event caution will prevail!

[Rich too]

At least you can leave the prop off for initial settings. Damn, you'll probably beat me to the maiden of my WW XL!!

[Adrian Smith 1]

One of the last jobs was to solder up an anti-spark connector lead which I bought from electricwingman whose mail order delivery was very quick by the way.

[Adrian Smith 1]

Connected up all the electrics and adjusted the working surfaces. Tested the motor and I did have to reverse the throttle channel on my Futaba TX before I started which was the correct thing to do as it turned out. the only thing left to do is to ascertain the position of the battery in relation to the CoG and I am aiming for the mid-range level at 165mm from the L/E. Ran out of time today so will have to do that another day. Anyway, took a piccy of the finished article which looks pretty good. Hopeful of doing the maiden in the next week or two. The elevators, ailerons were initially set at 30deg up and down with the rudder at 40deg. The ESC RX lead was slotted into CH3 which is throttle channel.

[Peter Jenkins]

I would recommend 10 deg up and down for both elevators and ailerons - these are good starting points for an F3A machine. You'll probably need the 30 deg on elevator for spinning and possibly more depending on where you end up with your CG. It will make a very twitchy first flight if you go with 30 deg!

[Adrian Smith 1]

Interesting Peter, I think I will readjust nearer your estimate as it sounds quite crucial and I don' t want end up having to fight to control it.

[MattyB]

Sebart F3A models are great, but it does seem like Seba likes to set his up more for 3D than precision aerobatics - the stock CGs seem to be relatively rearward and throws very aggressive. Follow Peters advice fora worry free maiden flight, 10 degrees will be plenty for starters.

Edited By MattyB on 23/10/2016 22:16:19

[Adrian Smith 1]

Thanks MattyB, +2 for 10 degs then. My style is for F3A rather than 3D so it's a good place to start as you say.

[Adrian Smith 1]

To get to my preferred CoG of 165mm (mid range) I needed to put the lipo as far forward as it would go and add 2oz of nose weight. This is because the lipo is a 3800mah 6s, as per the review. I accept that 4500s would have been better but I had already bought the lighter ones. However, I will invest in some 4500 s after the maiden flight assuming it goes ok. In the end I had to put the rx above the pull pull rudder servo using Velcro which seems fine.

[Adrian Smith 1]

Today was an ideal day for the maiden flight, clear day and not a breath of wind (although in hindsight a bit of wind might have been ideal. Still beggars can't be choosers). I don't mind admitting I was very nervous - what nervous you say, given my familiarity with big petrols? Can't explain it, but I was genuinely concerned everything would turn out ok.

Belt and braces for the battery and set the TX timer at 4 minutes to start with. Preflight photos incase disaster happens!

Edited By Adrian Smith 1 on 29/10/2016 14:39:37

[Adrian Smith 1]

Well the good news is that after two trimming flights this is the after flights photo.

So back on terra firm safe and sound. Phew!

My observations are as follows. I see what you guys meant about starting off with 10 degs of working surface movement. That was a good suggestion and she was still a bit lively even with CoG midrange. My only observation on the rudder is I could probably get away with a bit more throw, say 15 degs. I am amazed at how fast she seems to go and deceptively so. On the first landing approach I realised in time that I was coming in a bit too fast (wind might have helped here) so went round again to land successfully. I decided to let her slow up a bit more on landing the second time as there didn't seem to be an unannounced stalling issue. One bit of maintenance required was I noticed the plane pulling more to the right than I expected on take off roll out. This turned out to be a stiff U/C wheel which I put right back at the work shop. Next time out I will try a few aeros now I am confident of the handling capabilities.

 

Edited By Adrian Smith 1 on 29/10/2016 14:40:52