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Chub .15

Old 11-06-2011, 06:14 PM
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Toad
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Default Chub .15

here is an ASP .15 I did for the local races here. A work in process.
sports a venturi instead of the carb, pressure nipple installed on what used to be the mounting lug. (convenient)
Back plate mount and of course some trickery inside. oh yeah, converted head to use the turbo plugs.
note the hollowed wrist pin, mini skirt piston, smoothed rod, big bore crank with corrected timing. stock thrd on crank removed in favor of replaceable prop stud. After all, we belly land these on grass. usually I cart wheel em a few times. prop stud way cheaper than new crank.

the 15-300 class seems to be gaining popularity here. I am excited as I really like to fly that size and the cheapo engines are fun to work on
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Old 11-06-2011, 07:08 PM
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forsakenrider
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Default RE: Chub .15

Very nice as always toad! You got some numbers on your engines? This is a very interesting class! I wish I could get something going here.
Old 11-06-2011, 07:21 PM
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Default RE: Chub .15


ORIGINAL: Toad
the 15-300 class seems to be gaining popularity here. I am excited as I really like to fly that size and the cheapo engines are fun to work on
I'm guessing the 15-300 class is .15 CID with 300 sq. in. minimum area. Since you're tricking out the engine with some go-fast mods, are there any engine restriction rules such as starting with a commercially available motor or is it completely open ended on what you can run?
Old 11-06-2011, 07:36 PM
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Default RE: Chub .15

The engines allowed are the current cheapo's, The Magnum XLS from tower and the ASP or the SC clones. The idea is to run these affordables so you can rework all ya want on the stock parts. Have to use the stock muffler parts (or shells after a few lightning holes)
They seem to run around 100mph like our 1/2a's did, just the engines are available, run good and the plane is a bit bigger.. easier for my aging eyes.
I am hoping maybe a few more folk will play with us next yr.. maybe even a few out of state guys will attend once or twice. kinda like that funfly thing for small planes in the south.
This racing we do here is unique, they run 8 races a yr.. makes it worth the effort. Season points etc..
The 1/4 midget engines of yester year are not allowed.. only the Magnum and ASP
attached is the crank..bored out and off center. just thought I would mention that as I read a post where someone said he had a crank with the bore off center and claimed it a flaw. I do it intentionally to keep the wall thickness on the side below the crank pin when on the downward stressed cycle. can get a much bigger hole in there doing that. [8D]
sorry the pic is blurry.. I suk at that picture taking stuff. doing some port work in the other pic
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Old 11-07-2011, 07:17 AM
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forsakenrider
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Default RE: Chub .15

Someone is going to have to give you a photo lesson eh toad! Maybe I will come down and give you a crash course when I graduate from photography college in a year and a half! I cant even see where the offset is!

Jokes aside, that is a very interesting concept. Do you do anything else to counter balance the offset bore of the crank? or does it all just work out with the piston modified the way you have. Do you do anything to balance the piston and crank? I have heard of "precision" balancing methods, do you do any of the sort?
Old 11-07-2011, 08:51 AM
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Default RE: Chub .15

I think there used to be a class of club racing with Sig Scamp models near Toronto maybe 20 years ago that was fairly popular for a while.  Likely didn't go 100 mph, but I fly one of them with an LA, and it goes OK. I like the bluehead motors for the $ they can't be beat.  I played a bit with the AP .15 and it responded well to mods especially the big venturi and the very restrictive muffler, and equalled the ASP.  I should play with the ASP.  Did you raise the exhaust only, how much?  Mine ran 17,600 rpm with a 7-5 MA prop no head spacer and 18,000 with a radiused rod and cleaned up crank, no muffler.  The class of racing you have sounds good.  Stock motor rules are always bent anyways, but a standard cheap (and good) motor is good.  Hope it catches on.  Most people are into funfly stuff nowadays, it would be good to get the adrenaline going.
Old 11-07-2011, 08:53 AM
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Default RE: Chub .15

Too bad you can't use the old Qm15 engines.. I have a couple of Nelson .15's laying around doing nothing.

Do you have prop rules, like using a certain size, etc? Airframe rules, other than wing area?

Old 11-07-2011, 09:58 AM
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Default RE: Chub .15

No prop or fuel rules. Seems most folk are running the MAS S2 7x5 prop over 21500 here on 30%+ fuel
Most are raising the liner .010-.015 which raises the intakes also.. not good but they say it gets em a few rpm's I cut just the exhaust port until I get 165 degree timing and I leave the intakes where they are stock (132) Better setup but harder to do if all you have is a Dremel.
Old 11-07-2011, 10:53 AM
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Default RE: Chub .15

If the airframe is clean enough, you might go down on prop diameter a bit. We used to run smaller diameter props, around 5" or so of pitch (maybe 5.25) up around 27,000 RPM on the Nelsons. Of course, there wasn't any muffler, one of the reasons the event isn't around any more..

But they sure sounded cool in the air!

Somewhere I still have one or two of the carbon fiber props I had for QM15. Either that, or you could take the Rev-up 7-5N or the Top Flite 7-4.5 and re-work 'em to get the pitch, dia, and blade shape you wanted.
Old 11-07-2011, 10:54 AM
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Default RE: Chub .15

Toad: I've been looking for your Norvel mods page, I lost it in a hard drive crash and would like to print a hard copy this time-is it still online somewhere?
Old 11-07-2011, 11:41 AM
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Toad
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Default RE: Chub .15

try http://www.solmachine.com Im thinking the old Toadsrc will show there
Old 11-07-2011, 10:19 PM
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DeviousDave
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Default RE: Chub .15


ORIGINAL: Toad

try http://www.solmachine.com Im thinking the old Toadsrc will show there
It does, but didn't it used to have a how-to section for massaging Norvels into fire-breathing vodka burners for pylon racing?
Old 11-07-2011, 10:29 PM
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Default RE: Chub .15

Toad, your profile still show the old URL! Thank for the new one you should update your profile.
Old 11-08-2011, 10:26 AM
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Default RE: Chub .15

OK Dave, I will look for that page, I'm pretty sure I didn't delete it , just no link on the site anymore. Ill look into it. If I cant find it I wont be doing another page...soon anyway.. I'm lazy. lol

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