Magnus Electric Build Thread

[Lothar]

Step 5. Cut the access hole for the IDS pushrod arms.​

Although in the picture below I cut the hole going from the shear web through to the servo well before cutting the slot in the wiper, it is much better to make this hole after making the wiper slot, because you get much better access. (I forgot to take pictures on the holes I made later.)

I used a sharp pointed scalpel to cut through the shear web all the way into the servo well. A Dremel tool would be difficult to control accurately enough, and I found the shear web relatively easy to cut with a scalpel.

 

[Lothar]

Step 6. Make the apeture for the IDS horn.​

Finally apetures must be made in the flap and aileron surfaces to accomodate the IDS paddle horns. Again I found a scalpel to be the best tool for the job, and fine pointed tweezers to help clean out the flap and aileron cores after cutting into them.


This is the trickiest part of the operation, because it is easy to poke through the surface skin if you are not careful.

 

[Lothar]

Step 7. Glue the IDS paddle horn into the flap and aileron surfaces.​

Do a trial fit of the servo and servo frame in the servo well, and determine the optimum pushrod arm length for your situation. I used the 51mm arms for the flaps, and the 49mm for ailerons.

Next the IDS paddle horn is assembled to the IDS pushrod arm using the 1mm pin supplied, and then the paddle is glued into the apetures made with an epoxy and epoxy filler mixture. I used West Systems 410 Micro Light filler.

 

[Lothar]

Step 8. Position and glue the servo frame in the servo well.​

Insert the ball bearing into the servo frame and CA it into place, because there is no access to the bearing once the servo tray has been glued into place. Take great care not to get CA into the bearing itself! Attach the servo horn to the arm using the supplied 1mm hinge pin, then insert the horn into the bearing. Finally mount the servo, and mark the correct position of the servo frame on the well floor.

Disassemble and glue the servo frame using an epoxy and filler mixture like before. In my case the top of the servo frame touched the other wing skin (on the servo cover side) so I was able to glue that as well, making it a very strong assembly.

Once the glue has cured, assemble everything again, and test the servo travel with a servo tester or your radio.



On the ailerons the wing was so thin and the clearances so tight that I had to cut notches in the servo frames to clear the pushrod arms, see below:



Finished flap in the up position:



Finished flap in the down position:



I get a full 90 degrees of down travel, and still have sufficient up travel to mix ailerons into the flaps.

Is there an easy way to upload videos? I would like to show the flap and aileron travel.

 

[Konrad]

The only way I know to upload videos is to use a secondary host like You Tube and link to that site.

 

[Wayne]

Yes, best to use YouTube.

Looks good - I still need to do the servo install in mine. Was debating doing the really down and dirty method, but like the IDS.. I think I may do that on mine also.

 

[Lothar]

Video showing the flap travel:

Video showing the aileron travel:

 

[Lothar]

Elevator: I am using an FrSky HV5201

Specs
Torque @ 8.4v – 4.2 kgf.cm / 58.3 Oz-in
Speed @ 8.4v – 0.04 sec/60°
Dimensions: 23*12*29mm (L*W*H)
Weight: 23g
Servo Horn Spline: Φ5 25T
Operating Voltage Range: 4.8-8.4V
Max Refresh Rate: 333Hz



I glued 2mm threaded pushrods into the supplied carbon pushrod tube after cutting them to size and roughing up the section going into the tube.



Du-bro clevis on the end of the pushrod. Allows adjustment at both ends.

 

[Motowncali]

Lothar, have you flown this yet? Did it need the right and down thrust? Great built thread.

 

[Wayne]

Think he is having some ESC issues right now.

 

[Lothar]

Lothar, have you flown this yet? Did it need the right and down thrust? Great built thread.

Yes, I have successfully flown it. I originally added some side and down thrust as described in post 8 of this thread. Unfortunately I crashed it on the first flight, because I had programmed a Launch mode with some up elevator, and promptly forgot to switch it off while trying to get a handle on this hotliner. I had previously only flown sedate light thermal gliders. Anyhow the plane stalled on me, from which I was unable to recover. Fortunately my recovery attempts got me low enough that the plane was not a write-off. (Of course, with the Launch mode with too much up still on, it just kept stalling.) Only the nose got crunched, no other damage. The airframe is fortunately very strong!

So my first bit of advice is not to put in any up trim! This plane wants to fly fast! Which is the whole point really.

I did not put in down or side thrust in the repair, I don’t believe it needs it. When the motor is on, I want to gain height anyway.

I have had a successful flight with it, and I really like the way it handles. I bought it for the windier days, and it will be great for that.

As Wayne says, I am having some ESC problems. More on this when it has been resolved.

 

[Lothar]

Tip stall vs snap roll

I found the ’Tip stall vs snap roll’ article on page 8 of this RCSD issue very enlightening:

https://www.rcsoaringdigest.com/pdfs/RCSD-2004/RCSD-2004-09.pdf

 

[Motowncali]

Thank you for the update. Having had a few pylon racers, I didn’t recall any of them really having right or down thrust. Of course the manufacturer had cut the nose off just as this one is. Just aligned everything during the build.

 

[Wayne]

Yeah, I go for zero zero on the go fast planes.. Typically they have zero incedence on the wing and no washout too.

Lothar - Yep, no up trim needed! Plane should have plenty of power to get away from you. Some people will simply point the plane upward and then give full throttle. This really depends on the power setup and the airframe. I myself prefer to add a bit of flap and throw the plane out with 3/4 throttle. This adds a little washout to the wing to avoid a low speed stall on the launch. Later on, maybe the point up and 100% power launch once I'm happy with things..

 

[Konrad]

As to rigging "pylon racers" I add right thrust as pulling the high G turn is the same as pulling into the up line of a loop as far as "P" factor is concerned. As we make left hand turns around the pylon the "P" factor will drive the plane into a tuck (point the nose into the ground). I add some right thrust to counter that, just like we do for the up lines.

Up and down trust lines are a balance issues with the CG. That is I set my pylon racers to track straight in the knife edge. I don't want the plane pulling towards the top of bottom of the plane. There is a bit of interaction between the CG and thrust lines to get this correct. I find that I need down thrust to have this nice knife edge line and not have the plane pulling up into a large loop on the straight aways.

I use washout as I want the root of the wing to stall rather than a tip. The root stalling will just open up the turn rather than having a snap into the ground.

Now on high speed sport planes I have a bit different rigging. But the idea is still to lower the pilot work load when going too fast near the ground. I really want the plane to go where I point her. I hate ships with a mind of their own!

 

[Hutch]

Hey guys! Just got my shiny new electric Magnus in the mail today. I couldn't wait for them to get back in stock after seeing both versions ripping it up at the Cape Blanco Slopefest about a month ago! The one I saw in Blanco had a ripping 6S setup that made for pretty spirited climb outs (that's an understatement). I may eventually go that route but I was curious about how well the recommended setup with the Typhoon 4W-25 and 9x7 prop performs. Will I be wishing for a little more umph?

Also...that IDS Install looks pretty slick Lothar! Super clean! I haven't tried that before, are they as strong as the "old fashioned" pushrod and control horn method?

Thanks in advance guys!

-hutch

 

[Wayne]

Good question - Still have not finished putting mine together. Things get stuck on my build table for LONG periods of time... As I recall it was going to be pretty darn good.

One of the guys here picked up a motor that might fit in there, it supports 7,500 watts. LOL Good luck getting enough battery in there, think the motor would take up the entire nose area. Mmmm, power!

 

[Lothar]

Hey guys! Just got my shiny new electric Magnus in the mail today. I couldn't wait for them to get back in stock after seeing both versions ripping it up at the Cape Blanco Slopefest about a month ago! The one I saw in Blanco had a ripping 6S setup that made for pretty spirited climb outs (that's an understatement). I may eventually go that route but I was curious about how well the recommended setup with the Typhoon 4W-25 and 9x7 prop performs. Will I be wishing for a little more umph?

Also...that IDS Install looks pretty slick Lothar! Super clean! I haven't tried that before, are they as strong as the "old fashioned" pushrod and control horn method?

Thanks in advance guys!

-hutch

Hi Hutch, apologies for the delay in responding, didn’t see any thread alerts. (This may be my fault if I didn’t respond to an alert for a different thread?)

At the moment I am using the Typhoon 4W-25 on 4S with a 9x5 prop, which is very fast (for me at least) when it gets going. My eCalc simulation told me that a 9x7 prop on 4S will be in a stalled condition until it reaches 37 km/h, so I was concerned about sufficient thrust for a hand launch while standing.

The IDS drives are great, they have survived an unexpected arrival when I stalled the plane. And very precise - zero slop!

 

[Lothar]

Revised Receiver Installation

After an unexpected arrival required some repairs, I decided to improve my receiver installation. I came up a 3D tray for the S8R Pro receiver. I added some insertion guides because the tray is mounted on a ply platform located way back in the fuselage. A removal tab is attached to the bottom of the receiver. I also added a retaining lug to hold it in position and avoid damage to the antennas (which stick out the fuselage) in case of a hard arrival.

 

[Lothar]

Receiver tray installed on a ply platform in the back of the fuselage. The body of the elevator servo can just be seen behind it.