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Seagull Hurricane Laser

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Jon - Laser Engines10/02/2019 22:47:20
4329 forum posts
159 photos
Posted by Martin Harris on 10/02/2019 22:13:51:

Is your tank the right way up, Chris? Difficult to tell from the photo - but you don't want to discover this on the maiden...

Yup, i spotted that. looks great otherwise though

Piers Bowlan11/02/2019 06:14:49
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1651 forum posts
41 photos
Posted by Jon - Laser Engines on 09/02/2019 11:58:33:

How close are the oleos to the surface of the wing? if they are really close you can just use little pipe clamps.

On my La7 i let the doors rotate slightly on the leg so that they would sit flush when retracted and not be all bent when down. I made little blocks to hold the door where it needed to be when up, and a flange on the retract cover plate to hold it straight when down

A photo is better than a thousand words, or at least it would be very helpful for my LA-7 project Jon, if you have time.

Impressive model Chris, following with interest. yes

Chris Walby11/02/2019 06:37:10
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773 forum posts
155 photos

I tired the tank either way around while I was looking at the engine/cowl position + I have a question regarding plumbing. The Seagull measurement is wrong as identified by Tim and I wanted to make sure I can move the engine back a bit if needed. The cowl seems easier than the Mosquito as I had less room to play with back and forth.

Jon - Laser Engines11/02/2019 08:34:12
4329 forum posts
159 photos

If you can move the engine back without upsetting anything then go ahead but dont bother if its going to make like difficult. Tims mod to his cowling goes totally unnoticed and has the added advantage of moving the engine forward for c/g and additional space for the tank.

Piers, the setup i used is now deceased as the doors on my La7 fell apart long ago. I keep meaning to repair them but have not had the opportunity.

The basic idea was that the doors could swivel on the leg but not move up or down. When up the door rested on two little blocks that kept it level with the wing. When it came down it rested against a small flange that i put on the litho plate covers i had over the retracts. This flange then held the door straight and it all worked quite well until i knocked them off.

Tim Flyer11/02/2019 08:39:11
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884 forum posts
145 photos

Chris just in case you haven’t seen it here is a link to the Seagull Hurricane assembly photo album I posted up . **LINK**

Tim Flyer11/02/2019 09:20:44
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884 forum posts
145 photos

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.

Chris Walby13/02/2019 06:33:33
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773 forum posts
155 photos

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

Chris Walby14/02/2019 22:16:41
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773 forum posts
155 photos

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

Jon - Laser Engines15/02/2019 08:25:00
4329 forum posts
159 photos

It looks like you have a shed load of up elevator in your photo Chris. Look at the position of the horn balance. Fly it like that and you will end up riding the rollercoaster.

Chris Walby15/02/2019 08:47:41
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773 forum posts
155 photos

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!

Jon - Laser Engines15/02/2019 08:51:41
4329 forum posts
159 photos

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

Chris Walby15/02/2019 09:28:10
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773 forum posts
155 photos

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.

Jon - Laser Engines15/02/2019 09:36:20
4329 forum posts
159 photos

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.

Chris Freeman 315/02/2019 09:47:18
142 forum posts
156 photos

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.

Jon - Laser Engines15/02/2019 11:20:48
4329 forum posts
159 photos
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.

Chris Walby16/02/2019 07:54:55
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773 forum posts
155 photos

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?

Jon - Laser Engines16/02/2019 10:28:17
4329 forum posts
159 photos

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.

Chris Walby23/02/2019 07:41:53
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773 forum posts
155 photos

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?

Bruce Collinson23/02/2019 08:54:19
250 forum posts

Chris,

sheet lead, legitimately, can come from a roofing supply merchant. Any friendly local roofer or jobbing builder will have offcuts kicking about.

BTC

Jon - Laser Engines23/02/2019 10:34:16
4329 forum posts
159 photos

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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