YT / ESM Hurricane - Laser 200 in-line twin

[Ron Gray]

Oil exploration next week, weather permitting. This tank will not be used in anything else otherwise it might leak (due to the hole in the side 😜) so brass tubes are only in place to stop any oil dripping out when (if) I fly it inverted for any length of time therefore no need to prep the ends for silly cones.

[Frank Skilbeck]

Hope you're not planning to reuse the oil 😉

[Ron Gray]

Top up the central heating tank Frank!

[Ron Gray]

Results of 2 x 8 minute flights, no mess under the fuselage but ¼” oil in the catch tank - not good

 

 

Even more worrying was this

 

 

Looks like rust and having contacted Jon it’s back to him for a strip down / investigation but gut feel says that I could be in for an extensive (expensive 😢) repair. In the meantime I’m going to use the 200 in-line currently in the Sportster so that I can continue flying the Hurri.

 

Another problem occurred whilst flying the Hurri, when I deployed flaps it banked to port but back in the pits both flaps were working fine. Consensus is that it is probably servo  ‘blow back’ so both flap servos will be replaced.

Edited November 26, 2022 by Ron Gray

[Kevin Fairgrieve]

23 minutes ago, Ron Gray said:

Results of 2 x 8 minute flights, no mess under the fuselage but ¼” oil in the catch tank - not good

 

 

Even more worrying was this

 

 

Looks like rust and having contacted Jon it’s back to him for a strip down / investigation but gut feel says that I could be in for an extensive (expensive 😢) repair. In the meantime I’m going to use the 200 in-line currently in the Sportster so that I can continue flying the Hurri.

 

Another problem occurred whilst flying the Hurri, when I deployed flaps it banked to port but back in the pits both flaps were working fine. Consensus is that it is probably servo  ‘blow back’ so both flap servos will be replaced.

Ouch.
 

That does not look good.
 

[Ron Gray]

I’ll know how ouch ( 💷 ) once Jon’s investigated. Very strange as it’s the newest of all of my Lasers and none of the others are showing the same (rust) symptoms.

[Ron Gray]

5 hours ago, Ron Gray said:

so both flap servos will be replaced.

Nope, problem was a loose servo arm caused by the retention screw coming loose. Now fitted with a dab of thread lock.

[Artto Ilmanen]

Ron,

 

How did it sort out with the engine? 

 

Great model, by the way! 🙂

 

[Ron Gray]

The engine had to go back to Laser for a strip down and it was found to be rust. I still don’t know why this has happened, I have 20 Laser engines and none have this problem!

 

Jon (Laser) has rebuilt the engine and is just about to test run it and I’m waiting to hear what it has cost!

[Jon H]

Its all fixed Ron. I test ran it yesterday. 9600 on a 17x6! nice. Still working on the price

[Ron Gray]

Thanks Jon, I await with bated breath! 😱

[Ron Gray]

So having got the 200 back from Jon I thought that I'd better make a start on refitting to the airframe. On its last flight before the engine removal, I came in rather hot and it ran onto the grass runway at the side of our tarmac strip and it nosed over. When I picked it up the legs were still in place but a small crack had appeared in the leading edge near where the gear mounts so a couple of days ago I started to look a bit closer at it. OMG!

 

 

 

I could also get the cracks to open up when I applied some pressure to the outer wing panel so drastic action was called for (actually it didn't need to be this drastic!)

 

 

 

Yep I chopped the outer panel from the inner section!

 

This was followed by a complete strip of the underside sheeting on the inner panel which was just as well as I was a bit shocked by what I found. On the face of it, not too bad

 

\

 

But when you look closer, broken and partially complete ribs

 

 

 

 

 

 

But what really horrified me was the lack of any span wise support in the centre section, the spar stops due to the U/C leaving the balsa skins to take the load across the panel

 

 

So some extensive repairs and rebuilding are necessary!

 

[Peter Jenkins]

Wow Ron.  Never seen a saw like that used on a wing!   Serious bit of repair work there.  Good luck.

[Jon H]

4 minutes ago, Peter Jenkins said:

Never seen a saw like that used on a wing!   

 

Didnt you see my Spitfire thread? Ron i have clearly been a bad influence, but then again, it is only wood. 

[Ron Gray]

My trusty floorboard saw has previously been used on fuselages

 

 

 

 

[Adrian Smith 1]

I wish you well with that job, Ron. Look forward to seeing the results 🤞

[Ron Gray]

Thanks guys. I must admit that I did wonder if I was going the right thing when I started to remove the balsa sheet covering but I’m glad that I did. Fortunately the repair work I’ve got planned should be made easier as I have the laser cutter but I’m basically rebuilding the centre section from within!

[Ron Gray]

To start the repair works I have to have some new ribs so using the outer rib I traced the shape onto a piece of paper

 

 

This was then imported into Fusion 360

 

 

And a sketch made of the profile, noting that the top and bottom surfaces had to be reduced to accommodate the balsa sheet covering

 

 

I then copied this sketch and amended it as the TE depth increases towards the CL

 

 

I'm going to use these and cut out some Depron ribs to make sure that they fit before committing to the lite ply.

[Ron Gray]

Depron ribs tested for fit

 

 

 

Oops, good job I tested them in Depron first!

 

[Ron Gray]

Some measuring for individual rib fitting using one of the Depron template ribs

 

 

Then it was time to cut the ribs and check the fit, not too bad, just a little bit of sanding to fit then they can be glued in place. I've left bits of the old ribs to give me a greater surface area to stick the new ones to. The carbon sub spar will hopefully add a lot more strength for little weight gain, the ends of it are taken to the outboard ribs where the panels join together so any loads should be transmitted through the wing.

 

Edited May 7, 2023 by Ron Gray

[mike skingle]

Where did you mount the tank in you hurricane? You don't seem to have any running problems. 

I have the same hurricane and due to a shortage of laser 200.inlines I have fitted a laser 180 but to get the fuel tank any where near the level of the carb it'll have to go in the wing and on the bottom skin of the wing gets the centre carb only 2/3 of the way up the tank. The laser 180 is only 12mm taller than the laser 100 cylinder. 

 

 

[Ron Gray]

If you go back in this thread to page 3 you will see what mods I made to incorporate the tank

 

 

[mike skingle]

Ah Your tank appears to be rectangular  and difference in the cylinder height makes up the difference.

Also Very handy seeing how the wing is constucted as I have a bigger hole to cut in mine. So will reinforce the skin with some glass cloth.

 

 

[Ron Gray]

I have managed to get back onto the rebuild of the Hurri wing after having a few days away on hols! But I do need to pull the old digit out as the Laser Day is fast approaching.

 

I needed to re-join the wing pieces together before applying the sheet covering to the centre section as I needed to be able to clamp things together whilst the epoxy cured. To ensure that I was going to end up with the same dihedral as that on the other wing half I used a laser (not the engine) on a straight edge on the centre section and measured, at the wing tip, the distance from the laser beam to the tip, then did exactly the same on the 'loose' wing. Fortunately with the root rib hard against the centre section rib the measurements were the same, you could argue that, as that was how they were previously joined, there was no point in checking but I just wanted to make sure that things hadn't moved!

 

 

Whilst that was curing I cut 4 strips of balsa sheet, taped them together then used Super Phatic glued to join them and left them clamped in position with magnets to thoroughly dry overnight before I start the sheeting process.

 

 

 

[Jon H]

I test flew my Stampe today in preparation for next week. Generally no issues, but a long list of niggles to deal with.