Seagull Hurricane Laser

[Jon H]

The frustrating thing is that takeoff and normal flight is uneventful. If you keep it flying like a warbird and dont try too many loops its a walk in the park. I cant work out why landing should be such a challenge.

I wish it had not been so windy today as its likely that was misleading us somewhat, but even without the wind i suspect it would still have required careful handling.

[Chris Walby]

Well all I have to say is a massive thank you to Jon as I would have been using a bin liner by now!

It looks good and sounds great, seems to taxi and take off with no trouble. I had a very short stick wiggle and it flies very nice.

The problem is it seems to take no prisoners when landing.

No flaps and its quite quick and coupled with the mushing/delayed elevator ends in a resonating dolphin

Half flap, it seemed slower (no much) and on high rates on the elevator seemed ok, but still mushes and delay elevator response! No wonder Jon had his work cut out!

Full flap and it will fly slow, but the loss of elevator authority + a nasty pitch down if you try and add any power - almost impossible to do a go-around! and a fierce tip stall...

I am still using the OEM U/C and its very poor which might not be helping, plus I might reduce the full flap position (1/2 way between 1/2 and full).

https://youtu.be/taxtJw9INSk

We will just wait for a calmer day and test some more....

Edited By Chris Walby on 21/07/2019 22:08:01

[Federico Scapparone]

Hello everybody, any update on the landing issue resolution?

I've bought the mine time ago but I'm not assembling it given the issue you've met.

[Jon H]

not yet. Winter came and i have been hiding inside

[Tim Flyer]

Mine is still hanging in the garage ready to test after major repair. Unfortunately with my grass runway it might be a a month or two before the ground is firm enough after a record wet January. The Hertfordshire water table is almost at surface level on the fields and clay soil makes drainage very very slow.

[Jon H]

Last time i visited my field (november) it was like a marsh. My car nearly got stuck just sitting still for an hour

[Chris Walby]

The Laser is alive and being put to good use for the winter.

The Hurricane is sitting in the garage ready for better weather and additional ballast option.

[Tim Flyer]

One thing I did do when I repaired mine was to use a longer elevator horn. That might allow use of additional elevator travel whilst still not making the elevator over sensitive. The old control horn had broken and was replaced with a longer Mick Reeves fibreglass/melamine one. I also replaced the heavy solid billet aluminium tail wheel  rod with an aluminium tube. I like that “winter plane” Chris ! What model is it? 

Edited By Tim Flyer on 29/01/2020 14:15:48

Edited By Tim Flyer on 29/01/2020 14:17:59

[Jon H]

I think this elevator business is just a Hurricane trait. I was watching a video of a full size landing and as he came into the flare the elevator was up/down like a good'un with little to no response at all from the aircraft!

I think the setup of the sg Hurricane is really important but in my experience with Chris's model i think at least 50% is down to the pilot. Its just not going to float in like a butterfly and it needs to be flown every inch down to the ground. I am interested to see what happens when we add weight to the c/g just to make the thing heavier as this might help it stay a little more planted.

[Denis Watkins]

Just check Jon, schoolboy stuff

The throttle up, nose down trait, can be loose motor or motor mount

And on the elevator, just check Chris has left no expo in there

[Former Member]

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[Jon H]

Posted by Denis Watkins on 29/01/2020 15:01:47:

Just check Jon, schoolboy stuff

The throttle up, nose down trait, can be loose motor or motor mount

And on the elevator, just check Chris has left no expo in there

Both Tim's and Chris's Hurricane showed the same behaviour with the power on dive in landing config. My P39 does a similar thing and i think its to do with the thrust line being so high above the draggy undercarriage and the flaps moving the centre of lift further back. Not sure though and i cant remember if we did any thrust line tests in the air. Something else to look into!

As no expo we were clear of that as well.

[Tim Flyer]

I wonder if the very big radiator on the rear underside of the wing on the hurricane has something to do with the strange low speed handling

[Ron Gray]

Both of my YT Hurries dropped their noses when u/c was lowered but both landed really well with no bouncing. I mixed in some (slight) up ele when legs were lowered and nose down problems went away.

[Chris Walby]

Tim, its a Hyperion YAK 54 and came with a spare cowl for a very good price. Someone said it could be 10 years old, but its been well looked after. Flies so nice on 2/3 throttle with nice big loops, rolls and stall turns.

As for the rad I can see your point as mine is completely blanked off so it must add a lot of drag. I don't know if that would effect low speed handling though, but if I can find some suitable mesh I'll make it more airtex.

Not knocking yours in any way, but as you strengthened things up it might be a bit heavier than mine and there could be some irony if I have to add more weight.

Federico,

If yours is not Laser powered I would work out the AUW, take Jon's advice about control throws and join the hurricane club.

[Tim Flyer]

Nice plane Chris, I don’t think any significant weight was added by my strengthening as it was quite minimal ( in the order of 30g . I also used standard wheels, ( on some of my other planes I use Dubro Airwheels which are very heavy and add a lot more weight than strengthening) , I use those wheels as they have sealed tubes and cope well with our rough runway. On the Hurricane I kept the kit light foam wheels on.

[Federico Scapparone]

Thanks a lot everybody for the advices!

Even here in Italy our field is pretty sticky .

Hopefully we will be able to get back flying in march.

As regards the elevator what about increasing its surface?

Having it in my hand it seems pretty small compared to the wing chord, isn'it that - maybe - it gets some shadow effect during high angle of attack flight?

Thanks!

[Jon H]

Posted by Federico Scapparone on 29/01/2020 20:40:48:

Thanks a lot everybody for the advices!

Even here in Italy our field is pretty sticky .

Hopefully we will be able to get back flying in march.

As regards the elevator what about increasing its surface?

Having it in my hand it seems pretty small compared to the wing chord, isn'it that - maybe - it gets some shadow effect during high angle of attack flight?

Thanks!

The tail is very sensitive with only about 3mm elevator movement needed in normal flight. The problem is that little movement is not enough for landing but adding more makes the transition between flying speed and landing speed difficult

[ASH.]

"The tail is very sensitive with only about 3mm elevator movement needed in normal flight. The problem is that little movement is not enough for landing but adding more makes the transition between flying speed and landing speed difficult"

Can you not have a throttle/elevator mix on a switch for landing?

[Jon H]

not really. the problem is that you need to get the various mixes or whatever engaged before you have the problem so if you make these preventative changes too great the model is unflyable while you are trying to slow down to the speed where they work. As it is its a handful on the downwind as the elevator/undercarriage mix kicks in instantly you hit the gear switch even though the gear take several seconds to deploy. Even then, its too fast to be in trim so its climbing like crazy until you bleed off the speed. Get it slowed down, approach is nice enough but then you come to flare and your elevator has gone dead. To prevent that you kick to high rate on downwind while trying to drop the gear and wrestle with constantly changing trim.

Adding more mixes and complexity just makes it worse which is why i am leaning towards just manhandling it down.

All that said, last i flew Chris's model it was pretty blustery and that really didnt help us

[Jon H]

I just found this video. It clearly shows the problem with trying to land the hurricane and in fairness i dont think the chap did anything wrong, although loads of expo probably didnt help him. In any case its a nice visual of what has been discussed here

[ASH.]

Just a thought.. What if on finals you came in from height - full flaps down, quarter throttle, rudder opposite aileron and down elevator keeping the nose pointed down all the way . Just before touch down centralise controls engine on idle and land on the mains. No flair. That way you're manhandling it all the way down, just requires finesse . It looks like this model can't be floated down

[Chris Walby]

Ash, I'll let Jon comment on your suggestion, but from the sideline all appears to be okay until the air speed reduces. The elevator then becomes significantly less effective as it approaches landing speed to a point of being uncontrollable.

It has a thick wing section and Jon did a couple of (to me) very slow passes at height with flaps and gear down which leads me to believe it has a quite slow stall. The issue is it won't sit down until rolling very slowly.

The plan is once the weather improves to have another session in less windy conditions + have some additional ballast that can be added on the C of G. Perhaps less flap might help. We need to get inside the heads of Seagull as what they were thinking when they designed it.

PS My SG Mosquito Laser has a thick wing section, needs very little flap to land at quite a slow speed....common theme?

[Jon H]

Its a good theory ASH but the problem is the model isnt easy to control that accurately and its responses change significantly with airspeed.

I did try some high drag landings with loads of flap but the model just balloons almost uncontrollably.

When down to landing speed, and by that i mean the speed required to stop the damn thing rearing up once you touch down, its like trying to stand on a ball during an earthquake. The model becomes unstable in all 3 axes and control inputs to correct one divergence cause another. as mentioned earlier in the thread there is also this weird delay sensation where you apply a command to the elevator and there is a measurable delay in the response of the model. You can fix it with higher rates, but then its sensitive earlier in the approach.

What is difficult to understand is that the approach is lovely. It floats in solid as a rock, but as the speed bleeds off it just becomes unstable, especially in pitch. land faster then? no dice as a tiny touch on the runway will have you bounced back in the air 20 degrees nose high..which is not helpful!

Anyway, i am looking forwards to some decent weather and being able to try again as there must be a way to get the blasted thing down without it looking like a rollercoaster.

[Former Member]

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