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

VIDEO OF MY NEW MAGNUM

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Old 10-25-2005, 01:16 AM
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cobratraxxas69
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Default VIDEO OF MY NEW MAGNUM

Here's video from the maiden flight of my new Magnum (non R). It has the West .50 V1 and is turning an APC 9X7 (sure, I realize 8X8 would be ideal, but the LHS didn't have one). One thing I realize about these Magnums is that they don't like to be flared beyond a few degrees (keep it less than 8-10 degrees). I noticed that the horizontal stabilizer (which is angled down for some reason) will hit the ground beyond a certain angle and can shear off (which happened on my fifth and final flight of the day). Keep the plane nearly level for landing (although it will come in fast, as the video shows). The plane is VERY easy to hand launch (much easier than my Diamond Dust) with no tendency to torque roll to the left. Keep those aileron throws low, or it can be quite a handful.

Overall, the plane is a total rush, and the low altitude, high speed passes are AWESOME!!!!. The plane must have been doing 150+ MPH, as it is FAR faster than my 120 MPH (measured with radar) MVVS .40 Diamond Dust.


http://www.resume-connection.com/MagnumMontage.mpg

Whaddya think of the video? Does anybody have an idea of how fast it is going?

Thanks,

-Mike
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Old 10-25-2005, 05:58 AM
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strong
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Default RE: VIDEO OF MY NEW MAGNUM

Good video cobratraxxas69........to bad you don't have grass to land on, at such a great place to fly....the magnum is one great extreme speed plane.
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Old 10-25-2005, 09:08 AM
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Default RE: VIDEO OF MY NEW MAGNUM

I would say 150 mph....[sm=thumbup.gif]

FBD.
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Old 10-25-2005, 01:50 PM
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Default RE: VIDEO OF MY NEW MAGNUM

Cobra

Great video and I love the flying site. I fly mine in an area surrounded by trees so a small error can be a disaster. So far I have about 20 flights with no incidents and a grass area to land on. I use a dolly to launch, its easier and i don't have to worry about a bad hand launch which is inevitable. I have a video of mine but have no idea how to post it. can you give me a clue.

i fly in about a 1/3 mile circle so I estimate mine at between 150 and 160 depending on the day

Nick
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Old 10-25-2005, 02:43 PM
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Default RE: VIDEO OF MY NEW MAGNUM

From the sound on the video I would say you're either running way rich or have to much prop on there too. My West50 unloads way more than it sounds like yours is getting. What are you getting for RPM on the ground? If you're pipe is set right and you're propped right you can get 23,000 (that's what I've gotten on both my west50VI's) with the 9x7 and if your pipe is stock length you should be getting high 19,000's.

I'd put about 5 or 6 strips of clear packing tape down the bottom of it too so you don't wear through it to fast on your less than grassy landing strip
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Old 10-25-2005, 08:11 PM
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Default RE: VIDEO OF MY NEW MAGNUM

23K on a 9x7...? Wow, what was is doing on an 8x8... 25K?

Jeremy is right though... it sounds kinda rich. You could probably lean it out a tad more (but don't over do it).
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Old 10-25-2005, 08:45 PM
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Default RE: VIDEO OF MY NEW MAGNUM

Yeah, I'm probably running too rich. I'm still breaking in the motor, as those were the first flights. But I defintely feel that there is some more power in there, but of course I'm scared of running too lean and burning that $300+ motor out. How do I know when I've set the high-speed needle to the correct place?[sm=confused.gif]


I bought some 1 or 2mm plastic sheeting from Hobby People, cut it into strips, and super-glued it to the bottom of the fuselage. What was interesting was that only 1 area was showing wear, which was the region about 3-4 inches back from the propeller. The middle and rear of the fuselage hardly had any wear at all. But that front part was sure taking a beating!!
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Old 10-25-2005, 09:01 PM
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strong
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Default RE: VIDEO OF MY NEW MAGNUM

LGM graphix and rudeboy are right.......when you start your dive to setup your high speed pass it should get on the pipe and unload.....that baby should screammmmmm[X(][X(][X(][X(]
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Old 10-25-2005, 09:20 PM
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Default RE: VIDEO OF MY NEW MAGNUM


ORIGINAL: Rudeboy

23K on a 9x7...? Wow, what was is doing on an 8x8... 25K?

Jeremy is right though... it sounds kinda rich. You could probably lean it out a tad more (but don't over do it).

Nah, you read my post wrong, with the RIGHT prop and pipe setting you can hit 23K. I run an 8.75x8 cut down a little and my pipe is about 5/8" shorter than stock length. With the 9x7 and stock length I would think you should see 19,000.

Don't be scared to set the engine to peak. Running to rich can be detrimental as well, particularly if you are running castor oil at all. You will hear when the engine comes on the pipe, and yes, this engine will definitely come on pipe on the ground. Once you're there, keep leaning it out until you notice an RPM drop and immediately back it out 4 clicks. This should give you a slightly rich setting. My West 50 runs happily on the pipe all day. I run 15% nitro (which is as high as you want to go with this engine) and the OS R5 plug, I find the R5 to give the best performance and longest plug life

Jeremy
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Old 10-25-2005, 09:29 PM
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Default RE: VIDEO OF MY NEW MAGNUM

This plane is a hoot (or maybe it's the wonderful engine that makes it so fun ), but why did they have to angle the horizontal stabilizers down?? Especially considering that it has no landing gear. I'm not sure how I'm going to glue that right horziontal stab back on and have it be as strong as it originally was? (maybe put some reinforcing nails in or something?)
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Old 10-25-2005, 09:47 PM
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Default RE: VIDEO OF MY NEW MAGNUM

The horizontal stabs angled down on this plane I'm sure are for no other reason than to look cool and more jet like. On the old pattern birds it used to be to help alleviate roll coupling from a low wing. In many jet cases, the stabs get angled down so that in a high alpha situation the elevators don't get blanked out by the wing, I would think this is also partly why the magnum has the angled down stabs. I bring my magnum in at a high AOA and haven't busted the stabs, I do have a broken right stab from a bad launch right now though LOL. One thing to remember, if the balsa fits back together well, thin CA will hold it and it will be stronger where the glue joint is than anywhere else. This is of course assuming the balsa break left you with some "fingers" to glue it back together.
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Old 10-25-2005, 09:52 PM
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Default RE: VIDEO OF MY NEW MAGNUM

Thanks for the advice Jeremy. Unfortunately though it is a VERY clean break, perfectly straight across (flush with the fuselage). So do you think that CA glue will be enough or do u think I have to put some "rebar" in?
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Old 10-25-2005, 10:12 PM
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Default RE: VIDEO OF MY NEW MAGNUM

If it's not to close to the fuse (like a 1/2" away or more) just put some 2oz glass cloth along the break on both sides, just saturate it with thin CA. If you don't want to do that (since it will show through the covering after) then put in a couple of spruce spars. Another option is to use some 1/64" plywood, you can put a cover over the break on both sides and use some drywall spackle to blend it into the stab, then you'll never notice it was there when you re-cover it.
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Old 10-25-2005, 10:14 PM
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Default RE: VIDEO OF MY NEW MAGNUM

Oops, I'm an idiot, just noticed you said flush with the fuse :P I'd drill 3 holes and put some 1/8" hardwood dowel in the stab, drill into the stab portion in the fuse, and then matching holes into the stab half, then glue it good and solid. I'd add a fillet of epoxy and microballoons around it as well probably.
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Old 10-26-2005, 09:35 AM
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Default RE: VIDEO OF MY NEW MAGNUM

Bite the bullet......... and get another one........I think the plane itself is only around a 100 bucks.......at these speeds play it safe.....I don't think it would be worth the lost of your engine and radio gear if the stab blew off........also try to bleed off a little more speed and don't flair before touch down.
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Old 10-26-2005, 10:03 AM
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Default RE: VIDEO OF MY NEW MAGNUM

It's not difficult to do a repair on the stab that will be stronger than original. It's not so much that these planes are expensive, as you noted strong, they aren't, but getting them is another story. They seem to be a rare breed.

Biggest problem with the magnum is whatever speed you bleed off in forward motion gets picked up by the forces of gravity. I think this plane is REALLY affected by altitude above sea level. I fly at 2800' ASL and launch is a major pain with this plane. Landings happen at about 50mph, any slower than that and the thing is falling out of the sky at a rate that would be catastrophic to the airplane. I hear the stories from guys who say it's easy to launch, and the guys that say it glides quite well, well I can certainly say that at 2800' ASL it does not do either with any form of ease or grace LOL.

My landing pattern with this plane was always as such:

Upwind field pass: full throttle
Downwind pass: full throttle
Turn to base: full throttle
on final: half throttle
just before reaching the field: power off
touch down: approx 50 to 60mph depending on headwind
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Old 10-26-2005, 10:05 AM
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Default RE: VIDEO OF MY NEW MAGNUM

Thanks for the advice guys....I like the idea of drilling holes into the stab and fuselage and putting in dowels....think I'll do that [sm=tongue.gif]

I'm just too lazy to buy another one and set it up, I bought this one ready built from Bagostix
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Old 10-26-2005, 07:53 PM
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Default RE: VIDEO OF MY NEW MAGNUM

Hi cobra,

Just for fun, I extracted the sound from your video and ran it thru the doppler audio spectrum analyzer I used in the past to measure the speed of my Shrike 10 powered by a 32SX.

You made 5 passes:

pass 1: 129 mph at 16,650 rpm (inflight engine rpm)
pass 2: 144 mph at 18,035 rpm
pass 3: 124 mph at 17,323 rpm
pass 4: 141 mph at 17,037 rpm
pass 5: 126 mph at 17,151 rpm

The program makes some assumptions about air temp and distance from the camcorder microphone to the plane as it passes by, all which will change the numbers slightly, but generally the numbers agree with radar measurements within 3% or so.

A few of us made did some experiments a few years ago comparing dopplar speed with radar gun measurements and posted the results on the extreme speed forum. You can do a search for it if you're interested.

Darwin




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Old 10-26-2005, 08:39 PM
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Default RE: VIDEO OF MY NEW MAGNUM


ORIGINAL: cobratraxxas69

Yeah, I'm probably running too rich. I'm still breaking in the motor, as those were the first flights. But I defintely feel that there is some more power in there, but of course I'm scared of running too lean and burning that $300+ motor out. How do I know when I've set the high-speed needle to the correct place?[sm=confused.gif]

Well, for starters, try some different props. IMO, a 9x7 is as heavy as you want to go. If your pipe is still stock (uncut), than leave it there with this prop. Just fine tune the mixture a little, that should be good for a few hundred more rpm (from the sound of it in the video).

The West is a pretty well built engine... consider it broken in after about 10 to 15 flights, and don't be scared to turn that needle.
Setting the needle is pretty simple: warm up the engine and pipe for a few seconds rich, and then turn that needle in until you reach peak rpm. When you've reached peak, back it off again until you get a noticable rpm drop. If you have a tach at hand I'd say a 500 rpm drop from peak is the minimum you will want. That should be a good flight setting without risk of frying the engine or burning too many plugs. As long as the pipe is not shortened to the edge of being too short, the chances of really frying the engine are pretty small... but of course, a whole flight on a too lean setting will almost fry any engine.

For really peaking your setup, use a test stand: it makes things a whole lot easier.
Try an APC 8x8, or one of the Q500 props (cut down)... like an 8.8x8.0 or 8.8x8.5 cut down to close to 8" diameter. The engine really likes to rev, so the smaller props really make it come alive. Aim for at least 20000 rpm... 21000 to 21500 is even better with correct pipe setting.

Setting the pipe: use a sport 8x8, since it is a relatively light prop. Find the peak after the engine has warmed up and NOTE the peak rpm and the needle setting.
Now start cutting the header (a tubing cutter works really well) 1/4" at a time. Each time, take note of the peak rpm and needle setting.
You can make the point where the engine "pipes up" more "visual" by using the needle or even the throttle if the pipe is really too long. With the 8x8, the pipe at stock length and the mixture backed off a few hundred rpm from peak, slowly advance the throttle (preferable while taching the engine). Somewhere around 1/2 to 2/3 throttle the rpm will jump up 2 or 3000 rpm. That rpm is where your pipe is in resonance.
As you are cutting the header, you will see the rpm where the engine pipes up moving up the scale. (you will love this part )
When you start cutting, you will see relatively large increases in the resonance rpm. After a while the rpm increases will grow smaller... this is where you start being careful (you don't want to cut off too much).

If you want to stay on the safe (inexpensive ) side, cut the pipe only so much that the engine still easily pipes up. If you can richen the needle 1000 rpm before the engine falls off the pipe, you are safe.
If you want peak power, keep cutting until the engine struggles to get on the pipe. If you have to run the engine full lean to get it to pipe up, you have hit the sweet spot. Now, since your pipe is too short to determine a decent (flight) needle setting, you are going to have to use a smaller prop to set the needle at first. Use an 8x7 for instance... with this lighter load, the engine again will easily pipe up, and you can get a good needle setting (and take note of it) . Bolt the 8x8 on again, and take her for a spin. After a while you will get the hang of setting the needle without going to a lighter prop, but be careful, since this is tricky stuff...

A few side notes: the above procedure will eat up all of you header... you will have to start cutting the pipe too to get things short enough. And save some of those 1/4" and 1/8" header cuts... they come in handy if you have to lengthen the pipe again for some reason, just insert them into the coupler between the pipe and the header.

I will get off my soap box now...



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Old 10-26-2005, 08:44 PM
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Default RE: VIDEO OF MY NEW MAGNUM

Hi Darwin,

That's really cool that you went through all that effort, I really appreciate it. The 2nd pass I felt was the most impressive and is my personal favorite of all the ones from that day....now I can see that it is also the fastest! But it looks like I have a ways to go to reach that 200 MPH capable speed (is that capable with the West 50???). Now if I only lean the bad boy out......
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Old 10-26-2005, 09:25 PM
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Default RE: VIDEO OF MY NEW MAGNUM

Thanks Rude for that explanation about tuning the tuned pipe! Now I know exactly what "on the pipe" means.... looks like I might have some cutting to do
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Old 10-26-2005, 10:22 PM
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Default RE: VIDEO OF MY NEW MAGNUM

My experience with tubing cutters is that they flare the tubing inward slightly, which you don't want, As far as I'm concerned, either a cut off wheel or hack saw is the best way to get a cut with out altering the shape of the tubing.
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Old 10-27-2005, 10:21 PM
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Default RE: VIDEO OF MY NEW MAGNUM


ORIGINAL: combatpigg

My experience with tubing cutters is that they flare the tubing inward slightly, which you don't want, As far as I'm concerned, either a cut off wheel or hack saw is the best way to get a cut with out altering the shape of the tubing.
When using this procedure, be sure to stuff some paper towel up the header between the cut and the engine to prevent shards of metal from entering the engine. Pull the towel out after the cut. Better yet, though a pain, remove the pipe entirely, cut, wash, then replace.

You would be amazed at how much damage can result in a small amount of debris being sucked back into the engine. After all, that is how the tuned pipe works with a reverse pulse pushing exhaust/fuel/air mixture back into the cylinder.

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Old 10-28-2005, 06:39 AM
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Default RE: VIDEO OF MY NEW MAGNUM

Here is a video my Magnum. The flight patterm is a little over a third of a mile per lap, I estimate the speed at 130 to 150. Thanks to Cobratraxxas for handling the logistic of getting the video on here. The link is

http://www.resume-connection.com/magnum1.wmv
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Old 10-28-2005, 08:32 AM
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Default RE: VIDEO OF MY NEW MAGNUM

Great video Nick!!

What prop are you running ?

Bob
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