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Seagull Hurricane Laser


Chris Walby
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My engine ended up a little “forward” with a spinner gap which was easily eliminated with a disc made of painted black balsa that I stuck on the front of the cowl. It actually looks quite scale. If you move the engine further back you will have to move the tank back further into the retract well. The exhaust is quite close to the tank. I think I put some heat reflecting aluminium tape on the edge of my tank 😊. In my opinion it’s best to have the engine as far forward as practical. That minimises the cut into the wing and helps balance. Yes the fins do stick out a bit from the tapered nose but it’s not noticeable in the air and can’t hurt cooling.

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Update time,

Progress has been a little slower with me procrastinating with gluing the horizontal and vertical stabilisers. First I cleared the work bench and then I thought it might be better to try with the wings on in the kitchen. The kitchen worktop was no advantage as with the wings on the tail would be hanging off the side so back to plan A measuring off the wing tube.

Horizontal stabiliser went on with out too much difficulty apart from me cutting the covering back a bit too far, however the vertical was well wonky and needed quite a fair bit of fettling.

All glued now and it will be controls and wiring tonight, tomorrow looks good for flying and I'll see if I can borrow the club C of G stand.

PS - Thanks Tim for the link

 

Edited By Chris Walby on 13/02/2019 06:34:21

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Good news, after an afternoon of enjoyable flying and a quick bite to eat it was off to the garage with the clubs C of G tool.

Good news is C of G with out the cowl & tail faring is about 155, other news (as its not bad news just a matter of fact) is 800g on the engine line gets the C of G to 130mm.

All the servos have been connected and the flaps and retracts set up.

Now my attention has turned to the elevator and I'll reduce the travel, but based on Time and Jon's comment as after a little advice at to where to set the neutral point.

I can line the elevator up with a number of lines on the horizontal stabiliser (top, bottom covering line etc), but where is a good place to start.

Hope the photo helps

20190214_201108.jpg

Is that about right?

 

Throttle linkage and then fuel proofing + a load of small jobs and its nearly there...

Edited By Chris Walby on 14/02/2019 22:19:25

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Hi,

Its a bit weird because if you look at the top surface its straight along with the bottom but the horn balance looks all wrong. Put the horn balance in the right place all be its off set as Seagull didn't get the slot in the elevator in the right place!

I'll set it as you say and take a couple of photos and see if that's better, I appreciate it climbs under full power and don't want to run out of trim on the maiden (as there won't be a lot of travel available over all.

I was going for 7mm low rates (to start off with and high rate of 10mm which with will give a bit more on the trim travel and can be used if all is not going well, but and an emergency!)

Tim, could you post a couple of photos of where yours ended up trimmed as they are a good size and are know to be very effective!

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Can you take a photo exactly end on Chris as the balance looks really wrong and im not convinced that leveling the elevator with the strip of wood is the best method. I always eyeball it and reference the trailing edge and leading edge as in my dodgy sketch below. Just ignore everything in the middle and make sure the chord line runs straight from the leading edge, through the hinges (if centre hinged) and then to the trailing edge

elevator.jpg

 

After the trimming flight Tims model had its elevator perfectly level when viewed end on as i described above

7mm rates will be lively and 10mm likely a guaranteed crash

Edited By Jon - Laser Engines on 15/02/2019 08:54:44

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Hi Jon,

Will do as you suggest, I was not intending to fly with the 10mm its just if I set it for 7mm the trim is only a small proportion of the total travel. The result if I am a long way out is I'll run out of trim and then have to hold a lot of stick in.

I completely agree about the short travel needed once its trimmed in, its just getting as close as I can without having a model where you run out of stick travel and you need just a bit more, hence the unused 10mm travel.

I'll have a go tonight and report back, thanks for your help.

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I understand your thought but its so sensitive 10mm will just cause you problems as it will make the model too sensitive round middle stick. And no, expo wont fix it before anyone asks

And you will have to hold the stick crooked anyway when flying it as it, like all warbirds, is impossible to trim in pitch. Trim for 1/2 throttle straight and level then fly the rest. I probably use up to 1/4 down elevator on my warbirds on fast passes just to keep the noses down. At the top of loops the stick is hard back as they are then out of trim and trying to drop their noses. P39 is very 'bad' for this. Climbs like crazy at high speed and dives for the deck at low speed. But its balanced properly and, according to my research, behaves exactly as the full size did. Its just the way they are so you better get used to it!

If you arent comfortable with flying with crooked sticks then i suggest you take a sport model and put it a bit out of trim. Fly it like that for a day and just get used to how to fly it like that. It wont give you the exact same response but its better than nothing.

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Posted by Chris Freeman 3 on 15/02/2019 09:47:18:

I like to test fly with a little down trim as you will have less chance of the plane taking off at a slower speed than it should and it is easier to hold up than down.

i would probably agree with that, but at this point im so used to holding sticks wherever they need to be that i just dont care any more.

if the trim is badly out the best thing to do is FLY THE PLANE! dont worry about it, dont start trying to sort it out the moment it leaves the ground, dont start trying to faff about with the undercarriage if the thing is a handful, just fly the plane. Get it into circuit, gain some height, get the power back a little and then deal with whatever the problem is. If the model is only slightly out of trim then get the gear up asap, but if you are riding a bucking bronco then forget about that, just get the thing level and then worry about it. If its really bad get someone to beep the trimmers for you. Dont make life difficult by trying to do 3 or 4 things at once and you will get in a muddle and it will end in tears.

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Lost my nice log post, darn anyway last nights report follows

Rods as far in as they can go and 80% travel on the TX gets me 7.7 mm on the widest point so I'll settle on that.

Checked the elevator alignment and the previous photos showed it worse than it was although its did have a bit of "up" in.

Both elevators readjusted and it looks straight or very slightly down as per previous comments. Minor issue is I have now run out of adjustment and if it flies ok I could re-drill the elevator horns.

Photos as promised

20190215_174950.jpg

20190215_174215.jpg

With that minor success I fuel proofed the engine bay and fitted the tail wheel cowl !

I forgot to get the expanding foam around the tank and give it a go with silicone sealer later.

Found a lump of brass that will do as ballast to get C of G, but will see if I can find a lump of lead sheet that would fit better.

Any ideas were I can obtain lead (or equivalent) sheet from legitimately?

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that looks ok Chris, i think you will be fine. I see what you mean about the left hand elevator being low. They dropped a hinge point by the look of it. Also the chap that covered your elevators needs a slap! Unusually poor from seagull there.

One thing i forgot to mention was that with the elevators at a rate low enough to make the model nice in the air you may find it is very reluctant to takeoff. I ended up storming down the runway with full up in and it totally ignored me until it was ready. That is why we added the +15% elevator mix with the gear down, and + another 10 with flap down. What i recommend you do is leave the mixes off (or perhaps 2% just so you know its working) for the maiden but leave the tranny on the elevator flap mix screen. Then, takeoff, get the gear up, trim, fly...whatever. When it comes to landing drop gear and flaps at a high altitude and get an assistant to add to the mix until you get to a point where you feel you are at a good landing approach speed. Then you are all set.

This is how we set Tim's model and it worked out well.

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More progress

  • Pilot painting nearly finished
  • Tank fitted
  • Spinner nut made
  • Cowl cut
  • Electrics finished

I'll post a few photos later

Questions

Air scoop, instructions are ever helpful as just says epoxy. What would others do as its a fair size and if I have to ever do a wheels up/dead stick I would prefer if it didn't remover the complete underside. Looking at the instructions it does not say remove the covering so perhaps it will be ok

air scoop.jpg

Tim, where did you attach the lead? top of engine?

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What you could do with the belly scoop is mount it on 4 magnets in the hope that it would be knocked off and not smashed in the event of a belly landing. You might want to tie it on with a string for the first few flights though just in case the magnets let go

For the lead, what i did on my small hurricane was fold/beat the lead flashing into a roughly 15mm square stick. I then bent it into a horse shoe and mounted it immediately behind the prop driver using some thin strip steel screwed to the mount and captive nuts hammered into the lead. Its worked well and my making trimming the horse shoe on the band saw i can easily modify the amount of lead i have in the front

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Update time

Following the club inspectors checks which picked up a few valuable errors by myself the hurricane proceeded to fail its first noise test (wood 18 x 8 and APC 17 x 6) being just over the club limit.

Still not quite there with the C of G so a little more lead needed to be added + the flaps are binding a bit and needed the hinge line fixing.

Second go with noise testing today with Martin kindly bring a spare 18 x 10 prop and Inwoods posting a APC wide 18 x 8 prop that turned up the next day + me making an exhaust deflector.

Good news is it passed before the rain set in without the exhaust deflector or 18 x 10 prop needed.

Bad news when unpacking the model a club member noticed the flap push rod nuts were loose (in fact slid down to meet the other nut) and on closer inspection found I could just pull the nut down the thread !!

Its not very good and I'll either change the nuts/measure the threads or replace them with stainless studding.

Other than that its getting very close to maiden time!

20190224_145643.jpg

PS photo was last Sunday!

 

 

Edited By Chris Walby on 28/02/2019 17:29:17

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Good progress Chris! I hadn’t seen your updates . It’s a shame you have all that noise regulation to contend with too. The laser 180 is a very quiet engine in my view. Regarding weight, I used Lead struck on engine mount and just a little bit at the front of cowl stuck round the driveshaft cutout with gorilla glue. Gorilla glue works well sticking things in fibreglass cowls e.g baffles as it’s foam it also dampens noise. On my planes I tend to epoxy all the threads on clevises before flying. (Apart from rudder pull pull systems as wire can stretch) . Epoxy can be easily loosened with heat , but after getting all the servos and surfaces neutral I tend to glue the threads as just like you found the threads poor. i look forward to hear about a successful maiden flight. However be careful if you have grass as no point nosing over if it’s too soft on the runway . I’m probably waiting a couple of months to take my Hurricane up again

Edited By Tim Flyer on 28/02/2019 19:36:46

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Thanks for the comments Tim, I must admit I have used most of your and others suggestions for improvement and issues with the standard kit.

Quite surprising how quick it went together, the Mosquito seemed to take a lot longer , but then again the cowls were a far bigger pain to do due to their poor fit.

I have put the lead on top of engine mount as the cowl is not fixed by much and I have 900g up there, having said that I think its very close to 17.8 lbs.

Weather and especially wind can be a bit of an odd one as some of my models land quite fast so a bit of a wind (constant breeze) helps rather than if its dead calm.

I got bittern (my fault) by an electric Mosquito where I just did not appreciate it needed nearly 1/2 throttle to overcome the drag of the flap + U/C and tip stalled it. The Laser powered Mosquito flies quite slowly without flap, but talking to Jon I was using the wrong technique for a warbird so I need to practice the correct approach.

Our grass has already been cut and once it dries it can become quite low drag which means the roll out can be quite exciting as you approach the Armco/boundary !

The worst of the noise was from the front so I don't think it was the engine, but more the prop at WOT (probably the few times it will ever be in that position).

PS - I changed the nuts for some decent supplied by Model Fixings and they have nipped up a tread, once its bedded in I'll Loctite them in place.

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Good ideas ! I use and re use lots of model fixings hardware too. On some of these ARTFs I have also found myself annealing the push rods So I can then re cut the threads, as the nuts slip... The model fixings nuts and bolts are so much better. I definitely agree regarding wind. I avoid total calm with my Warbirds. I do find it helps to have wind on landings. My P47 is very happy in a 15mph wind. I also leave strong crosswinds out . For those days I’m happier flying sport planes. I flew my LA7 last weekend and it was great but really could have done with a bit more wind. I like to use flaps and throttle for landing but certainly am no ace !! Your Mosquito sounds great ! Jon is a great teacher on Warbird Flying technique. 😊

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Regarding wheel covers . I fitted them with home made aluminium brackets as per my photo album. The covers are slightly proud of the wing (a few mm)just at the rear due to u/c angle adjustment, but that makes minimal Flying difference. The massive radiator scoop adds loads more drag than those !

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Tim,

I'll do the same as you with the brackets and see what it looks like.

The original concern was that the wheel cover was raised on LE and TE (of the cover) and might flutter causing issues. Although that was before I fitted the engine and oil rad cooler cowls.

Did you remove the strip down the middle of the door cover?

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No I don’t think I needed to take that out as my HK electric retracts sit fairly deep in the wells . I cut the brackets with tin snips from thin aluminium sheet . They grip a lot better than the zip ties supplied and really stop the covers twisting. When I put them on I did use a zip tie just to hold them so I could put the small m2 retaining bolts in and accurately drill the hole in the covers .

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  • 3 weeks later...

No not yet, I was waiting for the better weather..oh its here!

Plus I had a kind offer of someone (with more experience than me) to do the maiden.

I'll chase him up.

PS the conscious is 130mm as pointed out further forwards means a faster landing and I would rather avoid that!

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Yes I suppose its somewhere in the middle when considering the general consensus. I have a fairly heavy petrol engine in mine and have been aiming for 120mm, so I am probably already at 130mm now as I was intending to add some nose weight. Similar to yourself I am waiting for better weather and a mowed strip before taking the plunge! Good luck on the maiden, try to get someone to film it as there's barely any videos of this plane flying!

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