Seagull Hurricane Laser

[Jon H]

10mm on the c/g will make next to naff all difference. The fuel consumed during the flight will make more difference than that. Its all about the rates with this one.

[neil martin 1]

Any update Chris, did she maiden? What was COG set at? Mine is all set to go...so maybe the weekend if weather remains good. CoG is set at 130mm and elevator rates reduced to 8mm. AUW is 18 1/2 lb

[Chris Walby]

Neil,

Update, due to poor weather, pilot availability and a couple other projects that have distracted me + I want more practice with a less costly model regarding full flap landing approach it has not been out of the hanger.

My COG is 130mm and AUG is around the 18 lbs (need to reweigh it as I can't find my previous note) so you are very close to mine and others.

Good luck with yours and double check your elevator is inline with the tail plane & Loctite all the U/C screws

[Tim Flyer]

My Hurricane is sadly no more ! I took if for a fly today in perfect conditions. I had added some up elevator mix when the gear is down to prevent pitching down on landing. I also moved the elevator from third servo hole to second making it about 1cm from the servo centre. The plane felt good in the air on take off which went perfectly. I retracted the gear and started a circuit . I noticed the plane was pitching up after the gear was retracted and put in quite a bit of down trim . Anyway the circuit continued and all felt good and I did a nice barrel roll. I then came downwind and gently turned back into wind at about 3/4 throttle the turn response was a but slow so I added more rudder. Anyway the plane went into a gentle descent and I just didn’t have enough rudder to pull it up. It wasn’t stalling as it still had speed in the gentle turn . The plane slowly descended and hit the ground flat . It seems the new mix and reduced deflection and down trim caused me to run out of elevator. The plane broke in two in the centre and probably isn’t repairable unless I make a massive effort . Lucky the engine is fine

[Tim Flyer]

This isn’t where it crashed it just shows it snapped in half . The main damage was all in the centre of fuselage . Tha impact was all under the plane as it hit the ground flat. 

Edited By Tim Flyer on 19/04/2019 20:26:24

Edited By Tim Flyer on 19/04/2019 20:28:06

[Paul Marsh]

Such a shame - It could be repairable. Don't bin it yet, you never know. I've brought back models from the dead before.

With Warbirds, you have to fly them with care, remembering to keep the speed up or have plenty of height. I reckon you had too little power - you said it wasn't stalling, true, but the wing wasn't producing enough lift either.

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

[GrahamWh]

Unlucky Tim - that's a real shame.

I've found that if you put the parts away for a while after a crash then come back to them later it all seems much more mendable than it does on the day.

[Jon H]

thats a pretty sad looking Hurricane. Ill give you a call tomorrow but in the meanwhile i agree with the other guys, dont bin it. From here the damage looks very repairable

[Tim Flyer]

Cheers Chaps . 😊. Silly thing was that my rates switch after I looked at the transmitter was on middle setting. I thought I had it on full rates... never mind . I’m not going to bin it as there are also quite a few good spares .

[ASH.]

Oh Tim, I'm so sorry to hear of your loss. It saddened me to read that. She was a beautiful model and I know you put a lot of time and effort into her.. Commiserations.

On the positve side - You have many other beautiful models to fly - you're a lucky guy! As has been suggested put her away - for a few days, then strip and then access the damage. I know your dab hand with the fibreglass and epoxy so you never know. See how you feel then.

Good flying weather the next couple of days.

[Tim Flyer]

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.]

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

[Chris Walby]

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 parts. 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 Walby]

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 Flyer]

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 Harris - Moderator]

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 Marsh]

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 Harris - Moderator]

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 Flyer]

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 Flyer]

Thanks too Martin...we live and learn 😊

[Former Member]

[This posting has been removed]

[Tim Flyer]

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 H]

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 Flyer]

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 H]

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?