Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Weston Magnum build issues

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Old 06-04-2003, 02:12 PM
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uk_speedfreak
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Default Weston Magnum build issues

Having recently built a Weston Magnum and kitting it out with a YS 45. I would like to warn you all of a potential flaw in the design.

Even with the ailerons double pinned beware that the hinges are likely to rip through the soft balsa trailing edge strip. I know this as my right hand aileron ripped out at approx 160mph resulting in a barrel role into the deck from 70' alt.

Another warning to all you magnum owners is that the aileron wire arm attaches directly into the soft balsa aileron and is prone to splitting the balsa due to flutter and vibration. I highly recommend that you insert a hardwood insert to the aileron and add longer wire servo arms to prevent this.

Unfortunately my magnum took 45 minutes to extract from the field and resulted in a total loss of everything.

Beware ....its a great looking bird is fast etc but at what price?
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Old 06-04-2003, 03:43 PM
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Cactus.
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Default Weston Magnum build issues

pinned? theres no pinned ones here, just a thought, if you forced something through, you may have split the wood along its grain, causeing your aileron to rip out.
also, dropping some thin cyno down the hole in the aileron works wonders, it also stops the hole enlarging.
pretty simple steps for most aircraft
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Old 06-04-2003, 10:48 PM
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Default Weston Magnum build issues

No pins here, and my ailerons are still attached...
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Old 06-04-2003, 11:42 PM
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Default Weston Magnum build issues

I just used thick CA (and epoxy on some), pushed it into the slots really good before I put the hinges in... so far they have survived a few power dives (which will have been faster than 160 mph I think)... so, knock on wood

You're right about the aileron torque rods though... mine had some play in the balsa...but no flutter yet...
I left them as they were as I already had the construction of a new wing in the back of my head while I was putting the kit together... It will probably turn out to be a complete new Magnum...

So far I corrected the following things on my Magnum:
-I did not use thin CA on the hinges
-I corrected the wing saddle for a clean, tight fit
-I glued a piece of brass tubing over the wing dowel (I don't like wood on wood)
-I tapped the wing mounting plate with M5 and use M5 nylon bolts now (almost lost one of the metal screws in flight once)
-I did not push the long metal rods into the plastic rods on the elevator linkage, I just used 2 short pieces of M2 rod
- I cut a rudder out of the vertical tailplane and used a couple of horns and nylon clevises so I can adjust side thrust (I had to trim the plane to the right very slightly, it flies much better now)
-I glued a strip of rough sandpaper on the CG range to the fuse sides under the wing, to make launches safer

All together small corrections that don't cost a lot of time and money, so I'm still pretty satisfied with what I got for the money I paid... this thing is really cheap speed...
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Old 06-05-2003, 10:42 AM
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Default Weston Magnum build issues

UK Speedfreak,

You should have returned the kit if the balsa was really soft. Soft wood on the controls of a speed plane usually doesn't work out very well. With that said, I've seen flutter destroy entire planes. That is the price we pay to fly at these speeds. The question is more, what caused the flutter? What servos did you use, did you seal the surface gaps, was there any slop, etc., etc..

Sorry to hear that you lost the plane.

Mark
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Old 06-05-2003, 01:48 PM
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Flying Irish
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Default Weston Magnum build issues

Just ordered my 1st magnum and should get it soon
all new to high speed stuff. What are you recommending to use, CA hinges or the hard Robart type? How do you fill the gaps?
Thanks
Kevin
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Old 06-05-2003, 01:59 PM
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Default Weston Magnum build issues

I have used the hinges that came with the kit and used medium ca to glue them in.

works great on the 2 magnums that I have......well at least one of them now, as human error has got rid of one :-)


SJ.
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Old 06-05-2003, 02:00 PM
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Default Weston Magnum build issues

Kevin,

It may be hard to seal the gaps with this new "non-stick" covering on the Magnum. I've seen hinge gap tape for sale, I don't remember where. I generally use clear monokote on ARF's.

The CA hinges seem to work good enough if the slot is tight. On many ARF's the slots are cut too wide. In this case a good epoxy hinge should be fine. Either way, you should have ZERO slop. Use servos that match the performance you plan to get. Some of the racing guys even put a piece of tap accross the aileron to wing tip joint to make everything even tighter.

Also remember the faster you go the less you need to deflect the surfaces. Use Expo or your rate switches. If you use the rate switches just remember to go back to a higher rate when you slow down (ask me how I know).

Mark
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Old 06-05-2003, 02:03 PM
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Default Weston Magnum build issues

SJ,

Not to say it won't work, but CA hinges are designed to work with thin CA. I've read anything other than thin CA can make them brittle and they may snap.

I've never strayed from the recommended process so I can't say for sure that they will fail.

Mark
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Old 06-05-2003, 11:03 PM
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Default Weston Magnum build issues

Originally posted by MMallory
SJ,

Not to say it won't work, but CA hinges are designed to work with thin CA. I've read anything other than thin CA can make them brittle and they may snap.

I've never strayed from the recommended process so I can't say for sure that they will fail.

Mark
The hinges that come in the Magnum kit look like some kind of "fibrous" matter... I used thick CA just because of this... I though thin CA would make them brittle if they got completely soaked (CA makes everything that is porous brittle)

Most people will have used thin CA, so I guess it will be ok... I didn't and my control surfaces are still attached after a few dozen flights... I guess either way will be ok, as long as you get enough glue on those hinges...
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Old 06-09-2003, 05:56 PM
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Default Weston Magnum build issues

For info:
As a step in my mod-job on my first Magnum, i ripped out control-surfaces and hinges today... ...or to be more specific: After failing to rip them out, i had to cut the off and out with a sharp knife...

The "fiber-hinges" are a bit stiff, but they do not seem brittle at all.
When i buildt mine i used green Zap CA (medium viscosity) on the hinge-slots just before inserting the fiber-hinge, and after installing all surfaces and hinges i put red Zap CA (thin) on the hinge-locations.

When rebuilding it i'll use the same type of hinges again as they have really proved themselves in my opinion, and best of all: They left me with little or no gaps between the control-surfaces and the wing / stabilizer-trailing edge.

Other mods include:

-Joining wing and fuselage permanently, and using the canopy as access-hatch instead.

-To replace both vertical and horizontal stabilizer with ones that have tapered trailing-edges and thinner leading-edge.

-To add a tapered "tail-piece " at the en of the fuselage.

-To tilt the engine so that the manifold and pipe are aligned with the top of the fuaelage, and hidden in the canopy

-A new cowling that is more suitable for the new engine-position.

-Making a fueltank that is more suitable for the available space in the Magnum.

-Glassing the whole thing, both for fuelproofing and to make it more resistent for minor dents.

At this time it's in a lot more pieces than when it came in a box, and the rebuilding may begin...

-....and finally, glassing
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