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

Magnum tank installation

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Old 10-16-2007, 06:54 AM
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MJD
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Default Magnum tank installation

Nothing earth-shattering here, but someone had written me privately asking about tank options for the Magnum and I shot a couple of pictures of mine. So I thought I'd post them in case they are of interest to any other Magnum owners.

The tank used is a Jett 8 oz. "standard", which is 2" OD by 5-1/2" long. It's fits perfectly in the tank area, and juts out a bit into the radio compertment as you can see - which doesn't matter one bit since everything is aft of there anyhow. So far (knock on wood) I have not had one bad run, or blown a single plg, in fact after 30 some flights I am on the same plug and it still idles and transitions just fine. Also shown is something I did to satisfy myself that there wasn't a long length of silicone tubing flapping in the high speed breeze, which is a length of 1/8" Al tubing coupled to the pipe pressure tap and running between the pipe and the fuselage to the tank pressure inlet. Normally it is pinned down - originally it had a clip bonded into the fuselage side where that small chunk of silicone tubing is positioned near the middle, but I did a lousy job on the clip and it eventually came out. So the simple and obvious fix was simply to tie-wrap it to the pipe coupler. You don't see that here because I just trimmed the header a bit more and reinstalled it and haven't put a new strap on yet.

Anyhow, for those that haven't used them before, bladder tanks are dead simple to use, and since my experience with them in the Magnum I have installed them in a couple of other sport aircraft as well.

Bladder tank or no, I now make it standard practice to kill the engine in flight rather than let it run dry, and I am sure some are thinking "well, of course you do that silly!". Although I let it run dry a few times with no apparent problems (note that I do avoid the temptation to keep cranking the needle in for those last 37 rpm..) the problem is that I finally realized that every time I had a problem with the prop stopping near TDC, and thus hanging down to snap off on landing, was when I let the engine run dry. When I kill it in flight from full throttle, so far (knocking on wood once again) it has come up against compression and stopped horizontal every time.

Cheers

MJD

p.s. I took the foam off the Rx to see the back of the tank - yes it is usually wrapped!
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Old 10-16-2007, 12:06 PM
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rmenke
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Default RE: Magnum tank installation

MJD:

Really? Did not know props would ever stop anywhere else than vertical, at least for me. The up side, makes you a better flyer when you have to gently rock your wings at prop height during landing flair. Another reason I own APC stock. ENJOY
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Old 10-16-2007, 02:30 PM
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Default RE: Magnum tank installation

MJD......

great post. I received a few questions about that recently. I guess quite a few folks ran into foaming issues with the Magnums they were picking up off of the auctions.
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Old 10-16-2007, 06:09 PM
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ORIGINAL: bob27s

MJD......

great post. I received a few questions about that recently. I guess quite a few folks ran into foaming issues with the Magnums they were picking up off of the auctions.
I never bothered trying with the supplied clunk tank so have no input on that setup, I just put in a bladder tank from the get-go. 8 ounces is plenty for Magnum flights, you run out of amusing things to do with it before the fuel is gone*. I am also totally AR about prop balancing, and the engine runs silky smooth. I trust nobody even thinks about using plastic spinners.. [:'(] I also recall Weston advised that the props never touch the spinner opening as this causes a wear/stress point which can lead to puking a blade - made sense. I've run 9-6, 8-9 and 8-8 props so far with no problems other than the darn things snap when they hit the ground first on landing. I still have not got to my pylon prop trials, got distracted by a few other things. Manana, manana..

MJD

* occasionaly I find myself wondering how cool it would be to see it do a terminal dive at full throttle from 1000 feet and pile in about 100 feet in front of me with the camera rolling. [>:]
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Old 10-19-2007, 10:21 AM
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Default RE: Magnum tank installation

Hi gang I posted some for sale here on RC Universe. They are on Ebay also but I did discount on this site. So who has hit 250 mph?
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Old 10-19-2007, 10:48 AM
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ORIGINAL: hhager2

Hi gang I posted some for sale here on RC Universe. They are on Ebay also but I did discount on this site. So who has hit 250 mph?
Nobody has or ever will with a Magnum. Dream on dude!
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