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Seagull Hurricane Laser

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Tim Flyer19/04/2019 21:35:51
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By the way Paul I had a lot of speed and was just turning on a wide axis into wind . I’m quite used to Warbirds now but this one has proved extra tricky. I think the mistake i made was with altering settings to much and reducing the limit somehow with my mixes. The large amount of down trim I added early in the flight I think took out my up elevator limit.

ASH.19/04/2019 22:04:42
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282 forum posts

'altering settings too much'. That what it was Tim. A good reminder for us all - only change one variable at a time.

Chris Walby20/04/2019 06:34:54
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Tim, Very sorry to see your Hurricane, like the others have said put it to one side and have a look at it a bit later on. As long as the repair does not add a significant amount of weight I think you will be okay.

Remember during the war a full size was flown with a fabric wing on one side and a longer ali skinned due to lack of available partswink. My understanding is they are quite stable if not a bit of a handful to get set up right.

Thanks for your detailed summary of what happened as it will be valuable for other SG Hurricane owners and general flyers.

I hope you can get her back together again.

Chris Walby20/04/2019 06:56:13
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Looking at your photo most of the repair will be around the TE area on the fuselage which won't affect the COG too much and looks quite a clean break.

Apologies for prying but I noticed both elevators were detached, was that due to the impact and that they wrap around the horizontal stab?

Tim Flyer20/04/2019 10:02:51
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991 forum posts
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Hi Chris I hope this helps that’s why I decided to post it so everyone can learn something. The plane was traveling quite fast . I estimate 40 maybe 50mph in a wide turn with an axis of about 80m or more. That should have allowed a nice upwind pass along our runway. The plane was in a very very shallow dive maybe 10 degrees down from horizontal. I was using a lot of right rudder (normally I would just use a bit of right rudder in the turn ) as the right aileron seemed ineffective . I needed to get round the turn as we have a tree near our runway . I was using full elevator but the plane just flattened and didn’t gain height. The throttle was at 3/4.

Looking back on what might have saved it.

1. Full Throttle. I was on 3/4 . The ballooning effect of full throttle might have lifted it.

2. letting go of the rudder ( trees were about 100m ahead)

3. Full rates ......unknown to me as I thought I was already on full rates I was on the middle rate on the 3 position switch with much reduced travel.

4. I seem to have made an error when setting up my dual rates on the transmitter ....my middle rate has 85% left aileron rate but just 60% right . That would have significantly reduced the right turn effectiveness . When I did the roll earlier in the flight it was a left hand roll!

The plane “flat landed” on its belly at fairly high speed . The down impact snapped the fuselage behind the cockpit. The cockpit was untouched. When the fuselage broke in two the front section moved forward ripping ailerons and rudder and taking them with it . The downwards impact wasn’t that great and the wing sad little damage apart from a bend in wing tube

Martin Harris20/04/2019 10:18:38
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Posted by Paul Marsh on 19/04/2019 20:33:11:

On downwind legs, always add more power, to keep the wing in lift, due to the airspeed being lower.

I'm afraid this is an old chestnut - the airspeed will not vary between upwind and downwind legs - only the groundspeed is different.

Your model flying at say 30 mph groundspeed in a 15 mph wind would only have a 15 mph airspeed - if it was still producing enough lift to maintain height then the angle of attack to maintain level flight would be very close to the stall and the model would be in a precarious position.

Before anyone raises the fabled "downwind turn accidents", they are caused by the ground based pilot attempting to make the turn look like he's expecting it to in still air - reducing throttle and adding elevator to maintain height leading to exceeding the critical angle of attack. The zoom exhibited coming out of into wind turns is due to the pilot being slow to relax the additional up elevator and power used to balance the tighter turn used to counter the drift effect.

Without wanting to divert this thread (feel free to look up the myriad of threads on this subject and take any discussion there) I'd just like to clarify that there is no reason to change the throttle setting when flying in any direction - throttle primarily controls climb or descent and airspeed is controlled by angle of attack (elevator).

Gusts close to the ground can result in coarse corrections leading to inadvertent stalls but all stalls are caused by an excessive angle of attack. Airspeed is the result of a balance between the drag caused by various factors including the byproducts of creating lift and the thrust - or energy provided by gravity (particularly in the case of gliding).

The bottom line is that you should not change throttle position in the circuit unless you wish to climb or descend.

Edited By Martin Harris on 20/04/2019 10:19:00

Paul Marsh20/04/2019 10:59:34
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3616 forum posts
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I always do maidens on full available rates, and a low rate if I need it. Usually I find if the aileron is sensitive round neutral, put some expo after the first flights if that's what it needs.

Usually, even after its test flown normally keep my warbirds on full rates anyway. I always fly with caution, keep the speed up, whatever anyone says, airspeed and height is your friend!

When flying, I;m always adjusting the throttle for the conditions and aircraft if needed, though in this case it was lack of elevator and aileron movement, not airspeed.

We live and learn...

Martin Harris20/04/2019 11:48:31
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8556 forum posts
214 photos

Good advice Paul - much along the lines I normally adopt although if I'm setting a model up for slightly less experienced pilots I tend to put a little expo in before the maiden if I'm expecting it to be of benefits (I'm aware opinions do vary).

I didn't see your detailed report before I posted earlier, Tim. The over ruddered skidding turn combined with up elevator might have provoked an incipient stall/spin even though the speed looked fairly fast over the ground downwind (see my previous post!) The total lift would be reduced due to the angle the flow was hitting the wing at and increasing back pressure to compensate may have increased the angle of attack to a point where lift was rapidly reducing and drag increasing.

Along with height and airspeed, balanced flight is also a good friend in these situations. Your analysis of the better options (isn't hindsight wonderful!) seems pretty much spot on.

Tim Flyer20/04/2019 11:54:04
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991 forum posts
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Cheers Paul . I agree we did the maiden last year and I thought I would have sufficient rates after my adjustments . Anyway the good news is

No engine damage (apart from new exhaust needed , but I have a spare anyway) . It does look repairable too. The Cowling is fine too with minimal damage near the exhaust outlet which is an easy fix .

Tim Flyer20/04/2019 11:55:32
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991 forum posts
165 photos

Thanks too Martin...we live and learn 😊

Andrew Ray20/04/2019 15:16:11
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698 forum posts
19 photos

...and I thought a Spitfire was the difficult one...

Sorry to see that Tim, I hope you can/do repair it.

My early flights with both an Eflite and 72” YT Hurricane were hairy to say the least, pitch down with full flap and YT recommending 20mm elevator each way, I had dialled in expo as well and I very nearly lost the model.

I found Jon’s (Laser Engines) advice invaluable from earlier in this thread, I reduced elevator movement to a maximum of 7mm each way and took out the expo (it doesn’t need it) and set this as low rate initially. The result was a much more manageable model that is nicely harmonised and well behaved on approach, I fly the approach with full flap which as much as I can get, about 70°.

Tim Flyer20/04/2019 21:01:25
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991 forum posts
165 photos

Thank you Andrew . I used to have a World Models Spitfire 60 and that was a great flyer . I must really stress that this plane is NOT difficult to fly I just mucked up the settings when I adjusted them . I have posted this in the hope it is useful to others and they will not make the same errors .

Jon - Laser Engines20/04/2019 22:22:39
4660 forum posts
173 photos

didnt get a chance to get on the phone today, been a busy one.

From your description i think your large rudder input may have been the trouble as trimming makes no difference to end point and only moves the centre position. Using large rudder deflection through turns with a warbird is unusual and not something i have ever needed to do. A small amount to tidy up the turns is always a good idea but 'significant' deflection may have caused a pitch down moment. My smaller Hurricane will dive sharply if the rudder is moved beyond a certain defection. My cap 232 used to do the same and was a nightmare to knife edge.

Even so, if the elevator travel was any where near where it was after we finished the setup flights it should have been more than man enough to overcome this as the elevators are very powerful. I didnt use the rudder hard over at any point during my time with it so cant say for sure, but it seems unlikely as the rudder authority was lower than the other controls when i flew it.

Tim Flyer11/06/2019 13:01:07
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991 forum posts
165 photos

The Hurricane is almost all repaired now . I just need to order a new fuel tank and buy a wing tube. And do a bit of painting and covering. Then final installation. While fixing it I have made a few small up grades. I saved 30g on the previously heavy tail wheel assembly. I replaced the solid aluminium rod with a shorter aluminium tube with a pressed in brass wheel collet to hold the vertical steel steering rod . I also used slightly larger elevator control horns which were from Mick Reeves Models which I had in my spares box. The longer horns should enable use of full servo travel. When it’s finished I will post a photo 😊

Jon - Laser Engines11/06/2019 15:11:03
4660 forum posts
173 photos

Good new tim. Chris and i are still trying to find a day we can both do with weather that isnt pants so if you like we can keep you in the loop and do both on the same day?

Tim Flyer11/06/2019 15:58:54
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991 forum posts
165 photos

Cheers Jon Please do. I’m sure the weather will improve soon. I expect to have mine sorted in a couple of weeks now.

Edited By Tim Flyer on 11/06/2019 15:59:26

Tim Flyer24/06/2019 15:39:13
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991 forum posts
165 photos

All repaired now 😊

01bc84ea-1e83-405f-b827-bc8d410d9848.jpeg

ASH.24/06/2019 15:55:27
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282 forum posts

She looks beautiful.. Well done Tim!

If there's any pics of the repair please put them up.

Tim Flyer24/06/2019 20:39:57
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991 forum posts
165 photos

Cheers Ash I’m afraid I didn’t take pics as I went along.

The most critical and tricky bit was joining the two halves of the fuselage. One side was almost intact but there was a fair bit of damage to the wing seating on both sides. For the initial join I mounted the front half of the fuselage on a strong heavy wooden batten on my bench using the engine mount bolts on the firewall . With the fuselage positioned vertically I then put the rear half on it. I then tacked it together with cyano and then epoxy. I used fibreglass cloth and epoxy to reinforce where necessary. I think weight added will be minimal. I re skinned the sides with balsa from the inside and filled holes with slatted balsa, which was later sanded and clearcoted. I recovered with black solar film and re painted by hand with spare paint I had . I’m afraid the paint doesn’t quite match but I didn’t want to go out buying more. It looks fine to me but obviously is “very stand-off scale “. The radiator underneath was crushed flat but I just pushed it out stuck it with s bit of cyano then internally glassed and epoxied it . The outside saw a bit of body filler too. That was quite a fun repair 😉. The most important mod ‘( I think !) was swapping the tail wheel and replacing the over long solid billet aluminium tail wheel rod with a hollow alloy tube. That saved 30g on the tail !

Edited By Tim Flyer on 24/06/2019 20:41:11

Edited By Tim Flyer on 24/06/2019 20:42:08

ASH.24/06/2019 21:03:18
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282 forum posts

Thanks for explaining Tim.

I'm always amazed at what modellers can achieve with will and determination. I would have found that kind of repair quite daunting. Tacking with cyno is the first step and working in sections helps. I repaired my PC-9 a few times and she flew better than ever, but a broken fuse esp in that area is not for the fainthearted... laugh

Out of interest, did you use finishing epoxy with the fibreglass or regular 30 min?

Edited By ASH. on 24/06/2019 21:07:20

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