Segull Edge 540 60 First Version.

There is something "out of line" about this plane!

This plane has been through atleast 2 owners since new, it appears that as originally built as a nitro, it was showing signs of bad flight from the go. This is its second Fuse, the original was trashed on its maiden flight, it came to me with the original tail trophy.

This plane is/was a ARF, not a kit build.

It did fly again with the owner prior to me, however it seemed more a ground based vehicle. It would do 60 MPH down the runway and never lift off.....unless it hit a bump. Shortening the tail wheel to almost the point of dragging helped, however it seemed to fly with a "tail down" stance.

This plane has a strange negative incidence in the tail and wing, the 2nd revisions of the same plane, do not have that issue.

http://www.rcgroups.com/forums/attac...mentid=2441413

The last owner tried to get a new cowl, it seems they redesigned the plane and now have 2 sizes, the "correct" one was too small and would need heavy modification to make it work. I am rebuilding the original cowl.

If you have had this first revision Segull Edge 540_60, please let me know your dealings with this aircraft.

Hi Ron,
I've never has this plane but I hope you don't mind if I brain storm with you for a minute. What do they say about two minds being better than one.

Originally Posted by daoldguy

This plane is/was a ARF, not a kit build.

I hope some one that has had this first revision reads and replys to your blog because its common sense thinking that the need for the second revision was because of many problems with the first.

Originally Posted by daoldguy

It did fly again with the owner prior to me, however it seemed more a ground based vehicle. It would do 60 MPH down the runway and never lift off.....unless it hit a bump. Shortening the tail wheel to almost the point of dragging helped.

I read on RCG about another plane that would not rotate on takeoff and the LG/wheels were to far forward of the CG. They moved the LG "just in front" of the CG and it solved the problem. With this being an ARF you should not need to move the LG. So, I'm thinking CG.

Originally Posted by daoldguy

however it seemed to fly with a "tail down" stance.

This could tell us two things. 1. Tail heavy, CG to far forward. or 2. Something out of line with the thrust line.

Originally Posted by daoldguy

This plane has a strange negative incidence in the tail and wing, the 2nd revisions of the same plane, do not have that issue.

This may be the biggest part of your problem. Also, with the symmetrical airfoil the wing will need to be at a 90 degree angle from the fuselage (top and bottom) and straight as an arrow. I would measure the wing tip to the stabilizer on both sides for accuracy. This wing should fly the same upright as it does inverted.

If it were mine I think that I would realign the wing and horizontal stabilizer (along with the motor) with the thrust line. This plane should be straight with NO negative or positive incidence. It should NOT be greater or less than zero.
Everything should be straight on this plane. I would make the wing stright from tip to tip and make it nose heavy for the maiden flight. I would put the battery forward as much as possable to get the nose heavy.

That's just my thinking. I'm not near as good as you with models but I hope something I said may have helped.

Dalton

Originally Posted by DaDesign

Hi Ron,

I read on RCG about another plane that would not rotate on takeoff and the LG/wheels were to far forward of the CG. They moved the LG "just in front" of the CG and it solved the problem. With this being an ARF you should not need to move the LG. So, I'm thinking CG.

Both of the parties that have owned this ship are long time Nitro RC pilots and I have no worries about CG being a concern, he mentioned that had tried many things with the CG as a part of their troubleshooting.

Originally Posted by DaDesign

This could tell us two things. 1. Tail heavy, CG to far forward. or 2. Something out of line with the thrust line.

Tail heavy was a known issue with this plane, the last owner fortified the firewall <its bulletproof> with epoxy and used heavier motor mounts with helped correct the tail heavy issue.
The Wing and Hro Stab are both in line with each other, off set by 3/4 inch. They are for the most part they have it together. The belly is withing 1/4 of being inline with those surfaces, The top of the nose is 4 inches above the wing line, top of the rudder is 7 inches above the wing line.

Originally Posted by DaDesign

If it were mine I think that I would realign the wing and horizontal stabilizer (along with the motor) with the thrust line. This plane should be straight with NO negative or positive incidence. It should NOT be greater or less than zero.
Everything should be straight on this plane. I would make the wing stright from tip to tip and make it nose heavy for the maiden flight. I would put the battery forward as much as possable to get the nose heavy.

The more I look at this, the less arguement I have for negative incidence, in the picture the wing thrust line is near perfectly square with the firewall. These are not the right motor mounts, just stuck there for reference.
If I where to line things up like the newer revision, this would mean cutting the tail up to align the H Stab, the change to the wing would require cutting the saddle and dropping the back of it. Then my firewall would have an extreme amount of down thrust compared to the corrected thrust lines of the air surfaces.
I like all of your input, the fact is I think you may have a better working knowledge of this then me, I for the most part build from plan and tweak, you have done a little more designs. All input is very welcome!

Thanks
Ron

Hi Ron, I wouldn't give up on the 'negative incidence' just yet - if you look at Pic 'Seagull Edge 540 013.jpg' you can clearly see the wing isn't square with the firewall. This would also explain the 'tail heavy' attitude; it's not that the aircraft is actually tail heavy, it's just that the fuselage has to be angled upwards for the wing AoA to be enough for flight.

I think the only way to fix this problem is cut the wing slot again, changing the angle of attack of the wing to square with the fuse. Then rebuild/refill the slot and sand and finish it until it looks nice.

Just my thoughts

Originally Posted by Hughbert

Hi Ron, I wouldn't give up on the 'negative incidence' just yet - if you look at Pic 'Seagull Edge 540 013.jpg' you can clearly see the wing isn't square with the firewall. Just my thoughts

I thought the same thing, however the picture in my prior post 'Seagull Edge 540 022.jpg' seems to argue that. I can only think that 13 is an optical allusion due to the angle of the top of the fuse.

I am with you on getting the lines trued up. The wing saddle is solid all the way across the fuse where 4 wing bolts hold it in place. I thought I would cut under the saddle and drop the TE of the wing that way, then I will need to do something simular to the H Stab. The motor part would just be part of the electric conversion, I may have to modify the cowl to make the spinner appear true the the cowl.

Thought?
I will add some pictures of the saddle tonight so you know what I mean.

Ron

I don't think 13 is an optical illusion; if anything, it could be that the firewall is tilted downwards so the stab is level with that.

Look at it this way; you want the fuse to sit as close to horizontal in normal flight, right? And if you hold that fuse horizontal, or even just held it how you think it should look in the air, the wing (and probably the tail) will have a negative angle-of-attack; hence no lift, no flight. If you hold it so the wing has a slightly positive angle of attack, it will probably be in what 'looks' like a tail heavy attitude.

At least, as far as I can see from where I'm sitting Have you tried getting in touch with the manufacturer? You're unlikely to get a refund but you might get some advice.

Originally Posted by Hughbert

At least, as far as I can see from where I'm sitting Have you tried getting in touch with the manufacturer? You're unlikely to get a refund but you might get some advice.

Picture 22 with the square when veiwed close shows the firewall with a slight tilt up or up trust compared to the wing lines, I was shocked but could not argue it.

I emailed the Manufacture, looking for the original version replacement Cowl, and asked about the negative look, sent them some pics... no responce. I told them it was second hand, just looking for parts and info, no intent to ask for a refund.

Ok I see what you mean about the firewall. But you could always 'build out' the downthrust from the firewall after changing the wings by slipping some washers between the motor and the mounting screws, or by building a 'custom' motor mount.

Originally Posted by Hughbert

Ok I see what you mean about the firewall. But you could always 'build out' the downthrust from the firewall after changing the wings by slipping some washers between the motor and the mounting screws, or by building a 'custom' motor mount.

The electric conversion mounts will give me that adjustment so that part is really easy. I am not sure how much it will change the cowl where the motor comes out. Your vote would be to make it turn out like the pictures of the real 540 in the first post then?

Pretty much, yes.

I have one these w/ an OS 90--a very predictable fun plane going on its third yr..
From the flying view it looks like your right wing has gross neg incidence !
The rear fuse bolt hole for wing attachment controls this--your's looks to be too high in the fuse ---easy enough to correct. The wing should be parallel w/ the fuse edge where canopy rests.
A weak point in the fuse is around wing trailing edge (very typical) ---maybe this was crashed & re-assembled poorly w/ holes misplaced.

Originally Posted by staggerwing

I have one these w/ an OS 90--a very predictable fun plane going on its third yr..
From the flying view it looks like your right wing has gross neg incidence !
The rear fuse bolt hole for wing attachment controls this--your's looks to be too high in the fuse ---easy enough to correct. The wing should be parallel w/ the fuse edge where canopy rests.
A weak point in the fuse is around wing trailing edge (very typical) ---maybe this was crashed & re-assembled poorly w/ holes misplaced.

Hey SW.... Finally, a real world owner.

It was crashed so hard it got another ARF Fuse, These guys dont build kits or do any heavy repairs, it is Arf or nothing. I still have the Tail Trophy from the last ARF fuse.

This is a one piece wing, and the only thing I could see to do is drop the back <TE> of the saddle in the fuse to the right angle. Then I would have to make simular adjustments to the H Stab so it would be true.

You have any pictures of yours, I would like to compare the photos if you do.
Thanks for dropping into the discussion.

Ron

I learned something back in 1987-88 when I was doing pin stripes and custom graphics <Vinyl 3M Tape> for Trim Line Corp.

With pins stripes I could make a car look a totally different shape. Is there any chance the grafics on the 540 are playing with us?

See the attached artwork I did in PSP, this sort of changes things.

Ron

You have any pictures of yours, I would like to compare the photos if you do.
Thanks for dropping into the discussion.

Ron[/QUOTE]

It's kinda stored for winter---wings in my sailboat cabin wrapped in plastic & fuse in another area-(warm & dry) will dig them out & get some pics in the next couple of days --if time allows

You know you could ck the wing chord C/L ref to the fuse surface ref I mentioned by where the TE C/L & LE C/L sets in the saddle . That should tell you where you are to the thrust line.