Seagull Hurricane

[neil martin 1]

Wish there were more videos to view of the hurricane flying. Surprised by the minimal amount of reports on this plane since it's release.

[Jon H]

Posted by neil martin 1 on 10/11/2018 08:20:54:
Wish there were more videos to view of the hurricane flying. Surprised by the minimal amount of reports on this plane since it's release.

If the instructions are followed i suspect that many dont survive the maiden as the elevators are just too sensitive with the suggested 15mm movement.

I was intending to get some photo/video of Tims example but we obviously changed our priorities after the first flight excitement. If im there next time i will try and get some snaps

[Robert Bean 1]

Saw this site and thought I would chime in. Several of us here on the other side of the pond have had the trials and tribulations of the Seagull Hurricane. What seems to work is CG of 110-115 mm. Elevator throw of 20mm up and down with 40% expo. I extended the cowl and moved the engine forward 1.5". Also mounted the batteries above the engine as far forward as possible. The gear is mounted too far back causing nose over problems. Angled the gear as far forward as possible. Also shortened the gear by 1". With this set up the plane is almost civilized. I'll send pictures once I learn how to do it.

[Robert Bean 1]

[Jon H]

HI Robert

Your comments back up my original thinking in that there is a major aerodynamic issue with the model. Namely, the c/g and c/p are very close together and they cross each other in flight which makes the model very unstable in pitch.

Your solution, essentially making the model really nose heavy, solves the problem by moving the c/g out of the way but this obviously demands the undercarriage mods as well.

On the bright side, i suppose this proves that the model itself is just broken and nothing we have done has caused the problems. Its not like we got the dodgy friday afternoon model either as we now have at least 3 models documented with these same problems. Its also good to know that there is a 'fix' of sorts that means the models can at least be flown and not condemned to the bonfire.

The downside of course is that a great many people will buy these in good faith only to be badly let down by its flying performance.

[Ron Gray]

Such a great shame that ESM went pop, their Hurri was superb and I should not have broken mine

[Tim Flyer]

Very interesting Robert thanks for your useful contribution. Your Hurricane also looks great too by the way. It’s really good to see someone has tamed this very awkwardly designed model. Over here in the UK it’s rather wet at the moment and our grass runway won’t be good for Warbird flying until the spring. In the meantime I have taken delivery of a futaba 6axis gyro for next season to see if that can help with the unruly manners . My Laser 180 engine has also been removed and temporarily fitted into my Acrowot XL sports plane which can handle British weather more easily. 😊. My next major project is a DB Spitfire build which I can hopefully start once I have finished my house winter DIY projects!

[Jon H]

Tim, when we get out of lockdown and i can come visit i might poop over with my incidence meter and see what we are working with as i have a sneaking suspicion its all wrong.

[Robert Bean 1]

I flew for a living for a while. Have an Airlines Transport Certificate. I was forced to learn how to calculate Mean Aerodynamic Cord for the written and CG. Never had to do so at work. We had charts. Anyway, the following is the MAC info on the hurricane cg etc.

Here are the figures on MAC and CG:

130mm cg is 33% MAC - This is what the instructions call for. I think it would be almost unflyable.

120mm cg is 30% MAC - I found this to be tail heavy. 115mm was still a little tail heavy in my opinion, others may have different opinions.


110mm cg is 28% MAC - I found this to be ok, certainly not nose heavy.

105mm cg is 26.5% MAC

100mm cg is 25% MAC

[Tim Flyer]

Thanks fir the help guys . I look forward to better weather and being able to fly it !

[Robert Bean 1]

My cg is between 110 and 115, call it 112. That is about 29% MAC. It is not nose heavy. The Hurricane is very sensitive to cg because it has small horizontal tail surfaces. The 20mm up and down elevator travel could be less, but is useful to help prevent nose overs. To check cg roll inverted and see how much "down" elevator is required to maintain level flight. It should require just a small amount. This shows "positive pitch stability."At 112cg it takes just a touch. At 120mm cg none is required. This in "neutral pitch stability." Any cg further back "negative pitch stability." That is why the Hurricane with the cg 120 or more "floats" out of the top of a loop. Unstable on approach. It is tail heavy. Mine at 112 cg take positive up elevator to get the nose down on the back side of a loop so it is borderline tail heavy.

Most RC warbird "experts" suggest a 25% of MAC cg for a warbird, at least on the test flight.

The shortened gear and angle forward helps prevent nose overs. Also, with the tail strut mounted further down and shortened main gear the plane sets flatter. That reduces "P factor" on take off and makes 3 point landing less challenging, The 1.5" nose extension allowed me to remove a half pound of lead from the nose. A lighter weight is always good.

Just a note on the full scale. Most transport category airplanes have large tail surfaces and very broad cg ranges. Looking at light planes, a Cessna 182 has large tail surfaces and a broad cg range. A V-Tail Bonanza has relatively small horizonal tail surfaces and a very narrow cg range. Same for a Piper Cherokee. Small horizontal tail and narrow cg range.

So yes, this model was poorly designed. Landing gear mounted too far back and too long, nose too short and horizontal tail surfaces too small. Some times I think some of the manufacturers never test fly their products. Would have been easy to design it right.

[Tim Flyer]

Thank you for the information . Even Seagull themselves don’t have much in the way of videos of it flying. Having said that most Seagull models I have owned are really good. I also have their P47 20cc size which is a really excellent model and I fly it a lot .

[Jon H]

Yea Tim's model is not tail heavy and its trim neutral in level flight. It would be fine if the rest of the aerodynamics were correct.

My smaller 62 inch hurricane had similar traits to the SG version and it turned out the incidence of the main wing was wrong. With this corrected as best i can it performs well with a scale size tail. Its not perfect, but i couldnt completely fix the wing.

The size of the tail is only relevant when control inputs are not being made. The Hurricane is over sensitive in pitch and this would be improved if the tail, and by extension the elevators, were smaller as they would be less powerful. Again though, the divergence we see is due to the c/l crossing the c/g and changing all the pitch moments. You can get around that by making the model nose heavy, as you have.

In the case of the design, they would have been better getting the wing section right, as its a mess at the moment, and then make sure the incidences are correct. I have also flown a number of scale models with oversize tails and it makes them worse. Certainly i always use scale tails on my models where i can and the ones with smaller tails do fly better as the elevator is less sensitive.

Flying inverted to test c/g is also not a great idea as it depends very much on wing section. A flat bottom wing model wont fly inverted very well at all no matter the c/g!

[Robert Bean 1]

Jon, you may be right. Just giving my opinion. Anyway, set up as it is my Hurricane now flies ok.

[Jon H]

Posted by Robert Bean 1 on 15/11/2020 20:50:23:

Jon, you may be right. Just giving my opinion. Anyway, set up as it is my Hurricane now flies ok.

And to be fair, it flying well is all that matters. Im just annoyed that the model is such a moose as a great many people have been sucked in by a great looking model and i doubt many survive long

[Tim Flyer]

Agreed there seem to be few around given the usual popularity of this fighter. Here is a picture taken of it flying a couple of months ago. I think they do look good in the air.

[Robert Bean 1]

https://youtu.be/I-_dL0PMj0o

Here is a link to a video of the modified Hurricane. If the link works.

[Robert Bean 1]

https://youtu.be/I-_dL0PMj0o

[Robert Bean 1]

[Robert Bean 1]

Ok, I finally got the video posted. It was taken with an action camera mounted on my bicycle helmet so the details are small. Had the camera angle set on "medium." Next time I'll try narrow. As you can see the modified Hurricane flies ok now. This is my first effort at an RC video and editing. Thought I would post anyway with the dearth of videos of this model.

Jon, I don't think the plane is nose heavy. As you can see it lands fairly slow and with the gear shortened and angled forward the nose over problem is solved. In comparing the model to Hurricane three views, the center section of the model is longer than scale. The landing gear is longer than scale and mounted too far back, probably because of the sub spars in front. Also not angled forward. 

One way to definately determine if the model is nose heavy or not is to try a snap roll or spin. A nose heavy airplane will not snap roll, it will just do a type of barrel roll. However, a tail heavy airplane might not recover. In view of the full scale's poor spin recovery I have been too chicken to try a snap roll yet. 

The plane has twenty four flights on it since the alterations.

Edited By Robert Bean 1 on 14/01/2021 21:37:25

[Tim Flyer]

Well done Robert ! Really good to see another Seagull Hurricane flying !😊.

I’m certainly looking forward to being able to fly again after lockdown in the UK, and when the ground finally dries out. from its current sad and soggy state.

[Robert Bean 1]

I flew the Hurricane again today. Had to deal with a cross wind that was quartering behind, ahead and then direct cross. Takeoff and manuvors were ok. I took her up high and tried a snap roll. Good snap roll to the left and fairly quick recovery. Did several, was able to enter and recover ok. To me this proves the plane with the cg between 110 and 115mm is not nose heavy. At low level the air was rough with the wind rolling over a line of trees up wind from the runway but managed to land ok. On the second flight had to go around twice because of turbulence on short final. Finally got in ok. I thought it best to quit while I was ahead. Now expecting several days of rain and thunder storms. I guess that is better than several months of nasty weather. 

[Danny Fenton]

In my experience the Seagull Mossie and Chipmunk are both tail heavy as specified by Seagull, the Mossie almost unflyable, but a pussycat when batteries moved forward.

 

 

Cheers

Danny

[Jon H]

The biggest issue with the Hurricane is that its aerodynamics are broken. I have flown tail heavy models and while very exciting, they do at least behave consistently and predictably. The Hurricane...does not. You can do the same thing 5 times and, on occasion, get 5 different and mostly self destructive responses from the model. 

 

I keep meaning to dig out my incidence meter and have a crack at tim's machine to see where we are with incidence. With covid its not been a priority but hopefully there is light at the end of the tunnel and i will be able to get together with him and see what's what. 

 

If the incidence is a mess then we might have to do some mods and see what happens. 

[Geoff S]

Just came across this video on YouTube for the Black Horse big (87" ws) Hurricane. It seems to fly well but not as slowly as I'd like for scale.  Certainly seems to be better behaved than the Seagull version.

 

https://www.youtube.com/watch?v=Hy4qANuo4Us

 

Geoff

Edited March 22, 2021 by Geoff S
unsuccesful YouTube insetion :)