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Magnum building questions

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Old 09-04-2003, 01:47 PM
  #1  
seafury-RCU
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Default Magnum building questions

I was lucky to get one of the last Magnums before the new production run. I have a few questions about how to assemble and balance the plane.

1. Could someone explain how you can get the elevator pushrods to work without binding. Pictures would be good (do the white rods stay in the tube with only the metal section exiting? and did you bend the rods?)

2. Is there a simple rigging for balancing planes? I don't want to buy the GP CG machine because it won't very well on larger planes.

3. If you can't get prosynth, what fuel are you using? (ie. Is something like Wildcat suitable 15%nitro and 18% oil or should a total synthetic fuel be used - like coolpower). These are the 2 that I have available to me and would like to hear if anyone is successfully using either brand.

I've read through the long list of threads but didn't see direct answers to these questions. I'm very happy with the combo so far and can't wait to get it flying.

Thanks.
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Old 09-04-2003, 07:29 PM
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Ian.W
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Default Re: Magnum building questions

Originally posted by seafury
2. Is there a simple rigging for balancing planes? I don't want to buy the GP CG machine because it won't very well on larger planes.
Your fingers

the fuel: weston reccomend not to use over 15% nitro (made in england where fuel is expencive!) appart from this i really dont know, i use all synthetic (10% nitro) in my T1 engine with no problems.
dont listen to weston saying ONLY prosynth will work, its a big advertising con!

Ian
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Old 09-04-2003, 09:05 PM
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Default Magnum building questions

G'day Seafury,

I think the production quailty may have slipped a little with the last lot of kits. I too bought a later example and was a little disappointed with some of build quality, not all, just the wing fit and those damn elevator push rods. To answer you questions -

1. I couldn't get those to work either. I have 35 years building experience I haven't yet seen a more ridiculous setup, may be the earlier versions worked OK, but mine was just rubbish (far too much load on the servo). I turfed them out and used 4-40 rods with 2 DU-BRO ball links one on each side of the servo arm.

2. Not sure what the GP rig looks like, but the magnum is only a little plane. The balance on this bird is important use a rig that is adequate for the job. One thing I will mention regarding the CofG - Initially, I set mine up using the manufacturers specs, you've probably read about this in other posts here. Now its set at 140mm, she's very stable and glides in beautifully at the end of each sortie.

3. Pro-Synth is not available in Australia either, the importer here has recommended 18% coolpower with 10% nitro. I'm using this with no problems. I'll experiment more once the warranty expires.

A couple of other pointers for you -

1. If you can build a dolly for the magnum do so, hand launching particularly on the initial flights can end in tears, the torque roll on this baby is not to be taken lightly, severe comes to mind, but nothing you can't handle once you are used to it. I have a dolly for mine, she's never been hand launched since. Watching it scream down the rwy then pulling vertical is something to see.

2. Take it easy on the first couple of flights using a 9X6 prop. The magnum goes out of sight at a great rate of knots.

Got about 10 flights on mine now, getting better and faster each time. I'll be keen to have a look at the new version when released.

Hope this helps and good luck, let us know how you go.
Cheers
Ossie
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Old 09-04-2003, 11:25 PM
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Default Magnum Problems

Seafury:
I had the same problems with the elev. pushrods..
Did the same fix that Ossie used. then used a Hitec
5975 digital servo with 6 volts to make it smooth..

I installed a "T" nut at the 140 mm CG point and the
bottom center of the fuse. You may need this later
during repairs...
Then hang the plane using heavy twine and do both
lateral and CG at the same time.. May have to install
about 1 oz in a wing tip, that pipe is heavy, and battery
in the aft fuse

I use 15% fuel with 18% synth. and 1% caster oil...

If the engine tends to Snot Nose (loose fuel through
the front bearing) as mine did, replace the bearing
with a sealed bearing with the rear seal removed..
I see that in some of the new speed engines..
OK? Syd Clement -- When the motor stops the plane will LAND...
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Old 09-05-2003, 01:18 AM
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Default Magnum building questions

Thanks guys, but I need some clarification on the elevator setup you've developed. Bare with me if its a dumb question.

If you put a link on each side of an elevator servo, you will get a one side, one side down situation (ie. like the aileron setup). What am missing?

I'm confused

Also, did you continue to use the installed tubes to run the 4-40 rods and did you bend the rods?

I've always build my controls so that the linkages push perpendicular to the control movement. It doesn't look like this is the case with the Magnum.

OSSIE - I agree. The elevator setup could use some improvement and I'll be very interested in seeing the new version as well.

Thanks for the pointers. It looks like a fun package. I'm dieing to get it flying.

PS> I think most of the nice carbon fiber covering will fall off on the first flight
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Old 09-05-2003, 02:30 AM
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Default Magnum building questions

Seafury,
Unfortunately I don't have a digital camera, but heres a picture of a canard linkage setup on a eurofighter, this will give an idea of what I mean.

I removed the outer tubes replacing the whole lot.
The ball links a mounted on the servo arm, one on the top of the arm and the other on the bottom of the arm, I bent the rods so they exit the fuse at the correct angle then mounted the control horns to suit, 90deg to the hinge line.

Don't hesitate to ask if you need any more help.

Cheers
Ossie
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Old 09-05-2003, 02:42 AM
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ossie
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Default Magnum building questions

I could take a picture with my SLR camera, but I would need a day or two to get them developed and scanned to post them.
Let me know.....
Cheers
Ossie
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Old 09-05-2003, 09:23 AM
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Default Magnum building questions

elevator...

there is a little bit of plastic and a threaded rod. you screw the rods to the plastic, then the threadded rod goes in the middle hole. you put you METAL clevis on the end of this. kinda simple, looks c&p but works a treat, this solves your aileron elevator confusion.. in my magnum the rods stay inside the fuz with the metal push rods screwed in. the horns sit at an angle on the surface pointing right at the exit hole, i have no slop, no binding. will take pics because SOOOOOOOOOO many people get confused by this simple set up because they don't think straying from the way your meant to set up horns and such could work.

film... put tape on the edges.


if you guys are worried by your Magnums state, fit, finish etc you should see the ones here. for some reason these bags of $h*t will still take 200 MPH and the beating they get every weekend. all on 148 servos.


heres the pic... now that didnt take much working out did it
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Old 09-05-2003, 12:45 PM
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Default Magnum

Seafury:
Peal back the black covering and paint some thinned
(with Laquer) balsarite on the black covering. Let it
dry and iron back on with a 250 degree iron.
I also put a 1/4 inch red tape along the leading edge
of the wing covering to make sure it stayed down.

The two to one adapter is what I used on elevator.

Syd
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Old 09-05-2003, 02:08 PM
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Default Magnum building questions

Okay. I'm getting closer to understanding this now. Thanks for the elevator explanation.

Phillybaby - I think my hardware is slightly different then yours, because your word explaination doesn't make any sense to me. However, it is a simple setup and with some better hardware and some minor angle changes it will be a fantastic setup. I really appreciate the pictures - they helped alot.

I should be able to have it done this weekend.

Thanks everyone. I'll keep you post.
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Old 09-05-2003, 04:44 PM
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Default Magnum building questions

no, i didn't think my words mde much sense either, so i posted a pic. swap the links on the elevator for ball links and you'll solve any angle problems. however every magnum here inculding THE ORGINIAL! has this set up. only difference is some have the rod inside like mine, others have it come out, then bend the metal rod straight towards the elevator.
if theres a problem it would show up on magnum 001
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Old 09-05-2003, 06:48 PM
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Default Magnum building questions

Elevator rods: I just replaced the rods supplied with the kit with a couple of pieces of M2 threaded rod... instead of trying to push those long pieces of wire into the plastic inner liners I just threaded the M2 rods in. My M2 rods are about 30mm long, so they don't enter the fuse when you move the elevator... this avoids the binding issue at the rear end of the elevator rods.

Fuel: 5-10% nitro, 15-20% oil (synth, castor or mix) and the rest methanol... personally I feel my engine likes 20% oil better than 15%... but that could just be me (or the extremely hot weather we had the last 2 months)...
It really doesn't need 15% nitro... 10% is more than enough, unless you like the smell of burning money of course...
Don't buy the "use only Prosynth fuel" sales pitch. This engine, like almost all engines, will perform on most popular commercial available fuel brands.

Balancing: Before I built my own personal heavy duty adjustable balancing rig I balanced my planes on the table, or on two chairs for big planes... just use a couple of pieces of balsa triangle stock to put under the wings and use a couple of pieces of tape to mark the CG on the wing...
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Old 09-05-2003, 07:01 PM
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Default Magnum building questions

Phillybaby,

My curiousity is getting to me. If only one end is threaded, how do you have the other end attached? It doesn't look like you soldered the clevices on? Did you glue the metal rods to the inside of the white tubes?

Thanks.

PS> my wing saddle was perfect
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Old 09-05-2003, 07:05 PM
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Default Magnum building questions

They are pretty hard to push in... so they won't come out all by themselves... no glue needed...
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Old 09-05-2003, 07:40 PM
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Default Magnum building questions

I threw the white inner tubes away, and used the inner tubes from blue sulivan cables instead. No binding at all now.

SJ.
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Old 09-05-2003, 07:42 PM
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Default Magnum building questions

i brought it second hand built.. the rods are glued in with cyno by the looks of them.
when the first one turned up i ribbed him over the brittle looking push rods and pleaded that he change them, back then i was very worried about 200mph planes. since then the rods have proved them selves and its amazing what bodges will take that speed. my tail snapped off right at the fuz, i've pushed in cocktail sticks and glued it back on. more than good enough.
for some reason, the magnum puts very little stress on the airframe and controls when flying... but the surfaces are small so not much power required.
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Old 09-05-2003, 07:46 PM
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Default Magnum building questions

Magnum are just plain solid planes... mine has had several serious bangs (broken servo wires...running out of fuel at the wrong moment...you know the drill) and it turns out that this thing can take some abuse... Apparently the fuse is stronger than the supplied spinner...
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Old 09-05-2003, 07:53 PM
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Default Magnum building questions

Rudeboy - Thanks for your responses...very helpful...

The metal rods that I have are easy to slide into the plastic tubing. There is no resistance whatsoever.

OK... I won't beat this topic to death any longer, but its been a great help. This combo is great package. Hopefully it lasts longer than the first flight.

Either way, I'll just buy another

My first flight will be a hand launch with a 9x6 prop. It shouldn't need much of a throw should it?

PS> I don't like the smell of burning money.
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Old 09-05-2003, 07:53 PM
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its a simple design... apart from the wood under the engine its pretty much bullet proof.. however not water proof! the tail gets a bit floppy if you leave it in the rain. John wandered why it felt weird when he was flying it, couldn't get it trimmed. the tail might have been loose but it took the speed, and landed safely.
only one i've seen break up in flight was where he changed the mounting method but didn't pack the wing bolt plate to the wing seat, after a year he must have over tightened it breaking the wing joint. while inverted the wing split and parted. I've seen film rip off with a loud bang, a pilot soiling himself, but it didn't even phase the plane.
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Old 09-06-2003, 12:44 AM
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where did you guys get those magnums? do they have a web site?
Thanks
Edwin.
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Old 09-06-2003, 02:00 AM
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Default Magnum building questions

Edwin,

This is one possible source:

http://www.modellbau-usa.com

I believe they are in Florida. I don't think there are any Magnums available at this time, but if you call them they will probably put you on a waiting list.

Its a nice little plane.
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Old 09-06-2003, 09:00 AM
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the main site is www.westonuk.co.uk
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Old 09-20-2003, 04:14 PM
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Default Successful first flight

Just wanted to let everyone know that I had a successful first flight. Nothing to eventful...it was awesome and I think its going to be a lot of fun.

I think I will make a dolly for it as I don't always have someone to toss it for me.

I didn't do anything fancy for the first flight. I had an experienced hand launcher throw it for me, but with a 9x6 all he did was let it go. The torque was minor and only lasted a split second. Only minor trim changes were required. I could have flown it fine without trimming at all.

The landing was great as well. I came in fast and cut the throttle about a 100 m out and it came in nicely.

Its an incredibly smooth flier.

Thanks again for the help.

PS> In the end, I used SJN's suggestion and went with the nyrod elevator solution. It was the easiest to implement and seems to work great. The nyrods fit perfectly with no binding, so its a simple replacement for the stock white rods.
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Old 09-21-2003, 04:45 PM
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Default RE: Magnum building questions

Seafury,
Good to hear it went well for you.
I think you'll like the dolly takeoffs...................
Cheers
Ossie
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Old 09-22-2003, 07:46 AM
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Default RE: Magnum building questions

Seafury,

Clear Nail Varnish....

Paint it along all the seams and your film will never lift.
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