Seagull Dual Ace Laser Build

[Chris Walby]

Tinkering with the electrics as I'll go with dual RX lipos and a HK switch that will supply from either battery, so just need to sight the switch and connect things up.

I though I was nearly there with the nacelle cowls and with one finished though I was about there, but NO!

Having doubled checked measurements I can't get the two nacelle cowls to overlap without hitting the prop spinner. If I pull the cowls together at the spinner end, either the cowls won't sit flat (like getting creases in them) or the curved flange git of the cowl won't sit flat on the wing.

Any advice welcomed ?

I could pack one side of the nacelle out a little to stop the creases or trim the flange section of the nacelle flanges to get it to site back against the wing....?

[Chris Walby]

Well I got the nacelles to fit, can't say I am very happy about it although there have been some valuable lessons learnt as in the sequence of cutting, fitting and then drilling holes in the wing.

Pilot and crew turned up and the dual supply RX switch/UBEC and that's only because I needed a couple of small RX batteries in the back of the fuselage to get C of G. I don't think I'll bother again with a switch (the Speed Air I just open the canopy check the tank is full and plug the battery into the UBEC), ready to go.

The rest of the crew will need dark glasses the way I fly

With a couple of RX batteries on order it will nearly be ready for pre-flight checks, noise test and some ground runs to gently run the engines in.

I don't think there is a lot to add apart from a big thank you to all the guys that have passed on their help and experience over the build process, cheers.

[cymaz]

Can’t remember for the life of me but is there a bottom and top to the nacelle halves?

Edited By cymaz on 11/04/2018 01:04:55

[Tom Thomas]

Posted by Paul Marsh on 24/02/2018 12:16:34:

I have a C160 Transall and one engine quit on take-off, no-where to go and kept full power and full rudder to clear the hedge, cut the throttle as it flick-rolled, but leveled off and landed heavy in the field - the only damage was a bend wing tube and one wheel came off.

Twins are a great way to expand your skills - it would be boring if everything was easy. Engine-outs have killed full-size pilots, so not restricted to models. This is a classic ca

Edited By Paul Marsh on 24/02/2018 12:17:01

Paul, posting a vid of death and comparing it to our hobby? A "classic case" ?  Non comparable.......

Edited By Tom Thomas on 11/04/2018 03:48:12

[Tom Thomas]

Children died in that incident... gets me when children are involved in any life limiting situation.

[Chris Walby]

Cymaz, yes they are handed in respect that one fits over the other along the side joints.

I assumed that the top one would fit over the lower one, but perhaps not..

I think it must be me, as one fits where it touches (only kidding!) and was okay and the problem with the other was getting the two halves together without the cowl hitting the back of the spinner. The back of spinner to LE measurements are the same (although I did shorten the bulkhead back to get the Lasers in, but maintained the distance in the manual!)

The lesson learnt is dry fit the engines and bulkhead, then cut the cowls. At that point I could have eased the engines forward a few mm before drilling the mounting holes.

If I live long enough to retire I'll get another set of engine mounts and nacelle covers and go through the hole process again..in the right order. Until then I am going to enjoy the twins!

[Chris Walby]

Working through final checks including C of G as I ended up with a couple of smaller TX batteries and now the cowls are on and its getting very close to taking it up to the field for an inspection, range check, noise test and a few ground test runs (the Laser 70 in the Speed Air would have benefitted IMO) from more running in, before I impatiently had it doing gentle circuit .

I twigged that my standard glow stick is too long for the port engine as it hits the fuselage, Oh how I would have laughed if I had got to the field and assembled everything only to find I could run one engine! Better to have second stick anyway.

Elevator and aileron control throws needed quite a bit of taming and the rudder was initially way too little. Adjustments all made in low and high rates (looks like quite a big rudder with a lot of throw, but what do I know).

Hopefully photos and video of the initial tests soon.

[Jon H]

Sounds good Chris, let me know if you need anything.

When it comes to running in there really is no substitute for getting the thing in the air. I don't run any of my own engines on the ground longer than it takes to set up the needles.

Tom, not sure what prompted the resurrection of an old post but it was a classic example of a single engine accident. Nobody is denying the tragedy, but hiding it wont help educate others and prevent a reoccurrence of the same accident. be that full size or a model as we don't want either falling from the sky in an uncontrolled manor.

[Chris Walby]

Well with it nearly finished I couldn't miss the opportunity of popping up the flying field yesterday evening and doing some final checks.

I started with the starboard engine and found that I had run out of trim from shut to tick over (TX stick about 25% up) and gave it a gentle warm up.

And on to the port engine where I had previously noted that my standard glow stick wold not fit as it clashed with the fuselage. The LMS didn't have a stubby version so I bought a short plug/clip and found an old glow charger plug and a bit of soldering thus sorted.

Now its worth pointing out that the Speed Air (Laser 70) has only ever needed one squirt with the starter (throttle idle), glow plug on and away it goes, plus the Starboard only took two goes to start. The port engine refused to start...tried glow extension on starboard, that worked, but still no joy on the port! Must have wetted it.

Perhaps a faulty glow plug....the glow plug T bar is too long so wing 1/2 off, tried glow plug in stick and that worked, but with extension it looked very poor. Wing back on and tried it all again with throttle everywhere between 25% and 50% open and nothing.

Last try with throttle shut and away it went....well it would have done first time if Mr Numpty and primed it in the first place!

Warmed both up and did a few taxi tests just to get an idea of ground handling and what's available on tap.

I went back this evening and started both engines first go after priming them and using the glow extension lead. Couple more taxi runs and the decision to rework the servo throttle links as 25% of the travel is throttle shut to tick over plus I have a little sub trim in at full throttle.

[Chris Walby]

There was no more time for excuses as the sun was shining, hardly any wind and I had book a half days holiday just for flying!

The maiden all went well, needed some left aileron and a bit of up and didn't have too many issues although I didn't go more than 3/4 throttle.

Another club member turned up and I sort of rushed the start up procedure, but as it went so well on the maiden what could go wrong. Take off was a bit steep and I was having some trouble with it being rather pitchy, not helped by wanting the keep the speed up while I sorted myself out!

Problem solved as I had it on high rates, but by them I was still not happy so brought it in for a quick landing which I made a right dogs dinner of! Count myself lucky all I got was a tip off a prop for my sloppy start up procedure and missed the hedge by a couple of feet!

I'll post the video shortly

One last thing.......it sounds great most of the time, but once it flies past, its just superb!

[cymaz]

You’ve been bitten by the multi-engine bug...enjoy

[Rich too]

Excellent, well done

Btw I have bnib nacelle set if anyone needs them. I bought them for a project and did not realise they came in twos!

Edited By Rich too on 05/05/2018 06:12:58

[Chris Walby]

Rich, I'll have them please, PM'ed you cheers

 

Video link attached, best bit saved until last....Just my opinion but that sounds so much better than any electric I have ever flow

**LINK**

I'll see if I can get a video today with a few "lower" passes

PS - Thanks again to everyone who has helped out over the build its really appreciated  

Edited By Chris Walby on 05/05/2018 06:29:52

[cymaz]

Oh..can’t get the YouTube link to run. It might be me

[Ron Gray]

Not just you Cymaz, it won’t run for me.

[Ron Gray]

**LINK**

Sounds awesome but that hedge was a little bit too close for comfort!!!! 👍

Edited By Ron Gray on 05/05/2018 08:01:47

[cymaz]

I see it!

Edited By cymaz on 05/05/2018 07:58:56

That was some landing....fast 

Edited By cymaz on 05/05/2018 08:03:21

[Jon H]

Very nice. The engines sound good at high rpm but are a fair way out of sync at mid throttle. I think the left engine is running quite a bit faster looking at the stance of the model. Either way, looking good!

[Chris Walby]

No no Ron that's the director cut version....not for public release, I especially trimmed the last 30 second out.

How will I show my face again at the club...actually more people seemed to use the infield than the runway on Thursday anyway!...

I am never going to post ever again Oh I have posted again.... better go to the go to the LMS and get another 12 x 8 prop for later today.

Jon, Yes first flight they were both nicely together and it would fly much slower, the video I didn't take my time and paid the price for a sloppy set up (it was a hard yawing to control hence the decision to get it down. I think it would suit the 12 x 7 props better and if I mod the nacelle covers to absorb the noise that will help the low speed behaviour.

PS ...I never got over 3/4 throttle in flight as it just seems to get quicker and quicker at 3/4...I'll need Jubilee clips rather than bike clips for that

PPS that's with the noise tested limited throttle opening as well!

 

 

Edited By Chris Walby on 05/05/2018 09:25:52

[Martin Harris - Moderator]

Ron can rest easy that I'd already found the raw video so won't be to blame for any draconian action that your over-officious and notoriously intolerant safety officer will take this afternoon when I take the mickey commiserate with you over the loss of your propeller...

[Chris Walby]

Martin,

The Dual Ace will be the least of the issues, Dave's up for another bout of Vulcan flying and I still have the black ground squirrel to maiden...well further that the last 4 attempts!

Or we could try a hand launch Dave P style!

[Martin Harris - Moderator]

Great day at the club and Chris's models all performed magnificently - the SU47 lived up to Chris's nickname on the first attempt but tracked like an arrow on the second. Back on thread, I was mightily impressed by the sound of the twin Lasers - the sound track on the earlier video really doesn't do them justice. Excellent landing this time!

[David P Williams]

Thanks to all the useful info on this thread I have just maidened my Dual Ace. I incorporated several recommendations from here including a closed loop rudder and a Fults nosewheel. It has a pair of used SC52fs engines.

First flight was a bit hairy but after sorting the CofG and control throws properly it flies nicely and sounds fantastic. My first model using Taranis/OpenTX so a bit of a learning curve, but dead simple to setup each throttle on a separate channel, with a separate curve for each, so pretty much perfectly synchronised throughout the rev range.

Thanks to all who provided such useful information on this thread.

[cymaz]

Excellent!

[Chris Walby]

Well done and good to see another one in the sky.

Strangely I much prefer it in high rates than low (did produce some very impressive banks on to the flight line!).

I must be a bit odd as I do like the sound of a couple slightly unsynchronised Laser 70 as it heads away.

All the best and let us all know how you get on with it