Sessholvlaru

I had two MDS speed 15 motors with pipes...but they sell for next to nothing, so I assume they aren't any good. I might have to grab one of these when my fullsize SD build is through. I wonder what it would cost to have these ARF'ed....

combatpigg

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I only charge $40 / hour....so 20 hours should be enough to get one RTF. There might be less expensive [non union] shops in Canada, though.

MJD

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I have oft wondered the same thing myself..

MJD

MJD

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Today's lesson - why it's important to think about wood density.

One piece of 5/16" x 1-1/4" Te stock, I knew it was hard B-C grain, didn't feel too stupid dense, but I knew it wasn't medium. I cut a pair of elevons. On to the scale - [:-]

Next piece, quarter grain, felt pretty stiff, not as stiff in comparison but it felt more than up the the task. On to the scale - holy difference Batman.

The issue I found with the .15 CV-X and header was that it directed the pipe along one side of the tank compartment and was going to present a challenge in terms of accomodating a tankof reasonable size. So, not wishing to deal with that issue right now but preferring just to get on with it, I'll use the OPS instead. The total weight sitting here is 17.6 oz. So I think I can still make a decent AUW with this set-up. Plus it will look nasty and make stupid high rpm wailing sounds and convince everyone they need one of these.

I'm tired of building airplanes for the day now. Maybe I'll put some filler in the fin junction and put it away 'til tomorrow.

MJD

p.s. the color splotches on the lef ttip and here and there are the result of a slight slip with a single edge razor blade. First we had the red violin, now this..

Mike Connor

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I have a 1.5 x 3/8 x 36 aileron stock that weighs almost 50 g or 1.7 oz. The extra weight could hurt you as much as the stiffness would help from a flutter stand point. I refuse to use it the way it is and may drill 1/2" lightening holes in it and check the weight and stiffness again. Or maybe just toss it.

iflyg450

I am looking foward to getting a hold of this kit. Ditto on the Magnum 15, what a great little engine. Any thoughts on a Cox TD 15??

combatpigg

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Having the TD .15 on a Demon wouldn't satisfy the "Universal Cox Firewall Area Rule"

iflyg450

What does that rule mean??? I have a MkII 15 that I have never used.

combatpigg

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The Cox Firewall Rule.......all planes designed for Cox engines shall have a firewall with a cross sectional area equal to no less than 4 times the frontal area of the engine in question.....

Well, not so hysterically funny, I guess... but it seems like most of the classic 1/2A plane designs that I've seen for Cox engines were drawn up by some guy who works at PETERBUILT.......

MJD

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Just look at one of any of several .010 - .020 RC aircraft examples. I can hear the thought pattern now.. lessee, the .010's backplate is about 1" in diameter, so we better use a 2" x 2" firewall just to make sure it fits.

Speaking of .15's, I finally sent my two Conquests down to Ron Young to be ABC'ed and looked over. One of them will probably end up in one of these with a cowl and minipipe out the back.

MJD

combatpigg

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I think a TD .15 / Demon would be pretty impressive......I've only seen a Cox .09 on a SST ran in person and it was pretty sporty!. All the same tricks done to .049 TDs would still apply to the .15, I guess?

MJD

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At 4.45 oz it's light for sure, and might result in the only delta I've heard of that needs the battery pack forward to balance.

[link=http://www.mh-aerotools.de/airfoils/documents/cox_test_special_15_mk_ii_aeromodeller_march_1966. pdf]TD Special MkII test, Aeromodeller 1966[/link]

Here, the MkII showed a peak of 0.38 bhp at 18.5-19k on FAI fuel but the tester noted it seemed low on compression for FAI fuel, and that peak power climbed by 26% on 30% nitro to confirm that notion. So for sure, that engine on some decent fuel and a 7" prop of some kind that lets it spin into the high teens would result in some snappy performance. Loud, but snappy. There was mention of an expansion muffler available for 15 shillings. Might be a bit tough finding one now though..

Nice FF engine. And they look so purty.

MJD

iflyg450

What servos are you going to use?? Also WHEN CAN I BUY THIS KIT!!! Going with TD 15 MkII no muffler I'll use Sig Champ 35%nitro and a 7x4 APC should turn 17K ish.

MJD

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More pitch! But 7-4 is a good start. I think you'll see better than 17k based on the numbers from that review, but not sure.

Ummm...when? Not too long. I need to finish mine and test fly it (within one week), then sign off any changes and have some made. March sometime I think..?

I'm tickled with the weight and strength. I made the engine/radio compartment too wide, so I will slim that down and that will clean up the nose a bit - less pancake surface near the spinner. It holds a Jett 4oz bubble-free tank nicely as is, which is great for .15's and enough for .25's on a delta. Haven't checked Tettras against it yet, but will. Of course a plain old Hayes 3oz or GP 4 oz will fit too.

I think I'll be using HS-85BB's, they seem about right for this.

MJD

iflyg450

Hope it works out, I CAN"T WAIT TO BUY A KIT. You are doing great work for this hobby thank you

bob27s

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project looks like its coming along nicely

MJD

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The slim jim 4 ounce fits even better.

Tips are covered, sealed, sprayed day-glo. Now to cover the main panels in film, then on to the short strokes.

MJD

combatpigg

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Looks like you'll have it ready for S.M.A.L.L.!

MJD

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But I wonder if they have the sensitivity to truly appreciate a .15 running 30k on an open pipe?

MJD

combatpigg

My Feedback: (3)

I'd bring a bushel of foam ear plugs and sell them for $1 a pair.....[8D]

You could also set up a PA system so everyone can get an equal chance to hear it running on the ground.

To bad those air whistles don't work any better than they do, I've always wanted to give that a try.

If you follow this advice, you might not need to spend any money on gas for the trip home.

C_Roundy

I ran mine (mk1 apparently because it had both sides open exhaust) on a sig doubler in about 1975 when I was about 12 yrs old. It made it soo easy to begin to understand two stroke breathing, even in soft daylight you could read the mixture by looking at the open ports spewing their cherry red; at night it was spectacular to me, one of my most cherished memories before fast bikes and fast women.

combatpigg

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I've done a little night C/L flying, just looking at the flame. The lights in the background turn into streaks that don't leave your mind's eye right away. Not many places left where you can run open exhaust at night without getting shot at.

C_Roundy

HMM..., I am reminded of recent grapvevine rustlings about "SSRBEBPJ" (Super Secret Roving Bands -of- Europeans Brandishishing Pulse Jets) who set up their field gear for quick draw stormtroop deployment, drive big ultra clean and quiet vans to remote ancient farmland, quickly accomplish their nasty Druid Do, and move on before the descendents of ancient farmers figure out that it was not an ancient alien returning triumphiantly (or the God of Thunder)... Wash, Rinse, Repeat; same time, same Bat Channel three random direction counties away next week.

The noise restrictions in Europe are beyond severe, compared to here; and yet the worthy few find ways to "Git It Done" Are they fanatics? yes. Are they joyful right down to the core of their souls while they are doing it? Absolutely!!! Could you truly reconcile yourself to the same risk?
If you have to ask yourself, then the answer is................................................ .................maybe.

Combatpigg, I am not a smart man but I have a feeling that some of the things you lament for being gone from popular culture are not only alive and well in both of us, but are also in many others who would stand up if a leader ever really needed to rally them.

But regardless, if anyone ever shot you while you were, (or because of) flying an airplane; there would be Hell to pay from at least a few guys, including me!!!

There, I said it, I feel slightly better, back in tune with my Creator that is.

Cherry / Orange glow forever,
CR

combatpigg

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Wasn't the PJ used at one time by orchard farmers to keep oranges from freezing? Imagine several of them in a large economy size running 24/7........!

I'm sure Al Gore would get a kick out of that.....

Dauntae

I have a old Scande Demon kit sitting here, How does the Magnum run, I have a lightly used one and a NIB one sitting on the shelf and have not had a use for them (they were given to me by a friend who got out of the hobby) but this thread is getting me in the mood to put this Demon together, Do the Magnums get good RPM The only .15 I've ever used was a OS .15LA on my Lanier shrike othere than that all my engines are larger but want a little speed fix now.

Dauntae