"1/2 A" & "1/8 A" airplanes These are the small ones...more popular now than ever.

OS .15 CV-A question.

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Old 01-14-2010, 01:53 PM
  #26
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Default RE: OS .15 CV-A question.

I just looked at the prop and it's a 6.5x5.5.....that helps explain the unworldly mph claim I made earlier.
I run this engine on bladder, so the hole in the venturi is the same as the cranks' [more or less].
IIRC, it launches at about 23-24,000 rpm.
I haven't flown it since the "HowFast?" was borrowed from it and transferred over to the Screamin' Demon Programme....[8D]
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Old 01-14-2010, 02:04 PM
  #27
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Default RE: OS .15 CV-A question.

Disreguard then CP, I see giving you numbers with the two different carbs won't make a difference to you since you are running a fuel funnel on it anyway
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Old 01-14-2010, 02:18 PM
  #28
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Default RE: OS .15 CV-A question.

Come to think of it, it looks like a little spitoon.

Interesting how just .5 worth of pitch mutiplies out to a more believable inflight rpm?

The blades of these $4 props are much lighter than the $2 variety. APC just basically rocks.
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Old 01-14-2010, 02:34 PM
  #29
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Default RE: OS .15 CV-A question.

When I was trying to figure out what I had last year I couldn't find anyone selling them. They occasionally pop up on thebay.

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Old 01-14-2010, 03:28 PM
  #30
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Default RE: OS .15 CV-A question.

That header would fit on more than the CV right?
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Old 01-14-2010, 04:02 PM
  #31
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Default RE: OS .15 CV-A question.

Per the ad it will fit on the 10FP/15FP/all CZ/10FSR. After that there are different part numbers for different engines...I want one[&o]
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Old 01-14-2010, 07:08 PM
  #32
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Default RE: OS .15 CV-A question.

Oh yeah, so it says right there in front of my nose.. [8D] I was too busy looking at the picture then closed it.

Yeah I want two actually.

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Old 01-14-2010, 08:38 PM
  #33
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Default RE: OS .15 CV-A question.

Humm....CombatPigg I will try and go through the engines...We did flush them out (probably not necessary) and I did check the crank end play......I didn't go though the thing as I would a "stock" .40 for racing...It really wasn't mine to play with... They are on a 36" delta and some kind of little thin winged plane that came into the shop broken. I was just suprised that they wouldn't keep up with the fox (which is as you say a pretty hot engine). They may do better for straight line speed (we were flying figure 8)...the fox may have more torque than the little os's do. They do seem to be "honeys" really mild easy to hand start ..etc.

Steve
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Old 01-15-2010, 12:43 AM
  #34
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Default RE: OS .15 CV-A question.

Steve, I understand. I probably wouldn't take my own advice about grinding on the engine cuz I'm very happy with the way it is.......but it isn't anything near "pipe timed" for speed.

Besides, it's smarter to grind just out to 170 degrees or so and go the rest of the way with liner shims. This way you aren't overly commited and can always go back for more if the engine indicates it wants more.

36 inches is way too much span [and resulting area] for a .40-.50 powered delta to be real fast......24 inches is more like it for a .15 sized delta.
The "standard" for .40-.50 sized speed deltas is 32 inches.
When you get the right airframe married to the engine and prop, that is when the magic takes place.....
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Old 01-15-2010, 06:28 AM
  #35
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Default RE: OS .15 CV-A question.

Well, I just made the deal to get this liltle [link=http://www.rcuniverse.com/market/item.cfm?itemId=591760]CV-X[/link] of the market place here. I will get a CV-A crank, drive washer and back plate for it. And start with an 8x3 prop for some bench runs on it.
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Old 01-29-2010, 08:32 AM
  #36
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Default RE: OS .15 CV-A question.

I have my Donor .15 CV-X and all the CV-A parts to convert it to air use. I will dissassemble inspect and clean the donor this weekend while being house-bound by the impending ice storm due to hit us. Hopefully next weekend I will start showing some numbers comparing the stock CV-A to this Hybrid that should match the .15 DF engine MJD has. I will be doing my comparisons on the stock .15 muffler untill I can get a tuned pipe for it. Then I will pipe both engines and do it again.

Does anyone have a pipe set up for an OS .15 they want to sell?

EDIT:// Oh and when this is done I will be putting this little gem in a RaineDave Industries Sure Shark XV
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Old 01-31-2010, 07:19 PM
  #37
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Default RE: OS .15 CV-A question.

we get 20,000 on the fp15 with a 7x5 21,000 on some. they all turn faster as the get used. we set ours up to run on 5%. the magnum 15,s are very strong too. the best so far is the OS 18 boat engine with rc head on it. 26,000 on the 7x5

the OS fp 10's turn 20,500-21,000 on 7x4's we can get them down to 4 ounce's too.
with just a bit of work the fp's will out turn the cva and is much lighter. dont worry about letting them turn up. the irvine 15 we can get it to 4.25 ounces and still trun 20,000 on 7x5. this will get you 120+ on all the HB 1/12 scale planes if under 20 ounces. the round cowl planes are a shade faster
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Old 01-31-2010, 09:06 PM
  #38
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Default RE: OS .15 CV-A question.

I notice the CV-X data on OS's site lists the max hp at 29k, normal operating range up to 30k. I guess I won't worry about spinning it too fast..

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Old 01-31-2010, 11:43 PM
  #39
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Default RE: OS .15 CV-A question.

there is one of those OS 2f carbs left at tower. look in the scratch and dent section under engines. its new just discontinued. i would buy it but would tak to much work to get to work on a prop. i just went and got the link for who ever wants it.

http://www3.towerhobbies.com/cgi-bin/WTS1000p?&C=G
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Old 02-01-2010, 09:29 AM
  #40
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Default RE: OS .15 CV-A question.


Quote:
ORIGINAL: airraptor

there is one of those OS 2f carbs left at tower. look in the scratch and dent section under engines. its new just discontinued. i would buy it but would tak to much work to get to work on a prop. i just went and got the link for who ever wants it.

http://www3.towerhobbies.com/cgi-bin/WTS1000p?&C=G
The picture in the ad on Tower apears to be the R/C car carburetor (which I have) and you can not tune it while the engine is running as the prop would remove fingers.
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Old 02-01-2010, 11:21 AM
  #41
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Default RE: OS .15 CV-A question.

well maybe they have the wrong picture up or the wrong description. Sorry i wont help you anymore.
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Old 02-01-2010, 11:55 AM
  #42
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Default RE: OS .15 CV-A question.

Quote:
ORIGINAL: airraptor

well maybe they have the wrong picture up or the wrong description. Sorry i wont help you anymore.
Wow, I had to go a reread my post to see if I came off snippy or something. It truely was not my intention and your efforts to locate a carb are appreciated. I honestly apologize for offending you and please continue to contribute. I really did not mean to come off as you seemed to take it.
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Old 02-01-2010, 02:21 PM
  #43
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Default RE: OS .15 CV-A question.

no problem i was tired too long day at work got out late and had to be ine very early. thanks yes i will always help if i can. it just supports the hobby.
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Old 02-02-2010, 03:13 PM
  #44
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Default RE: OS .15 CV-A question.

On the quest for a tuned pipe for the OS .15 CV. I found one at an RC boat store (online) [link=http://www.funrcboats.com/ProductInfo.aspx?productid=OS1611]here[/link]. What do you guys think? Will I get some more revs with this?
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Old 02-02-2010, 05:03 PM
  #45
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Default RE: OS .15 CV-A question.

Tower hobbies has about the same pipe if you like to order from them. Just search MAC's products
It's the mac's tunned pipe 2.5 .10/.15 - about the same price. I bought one for a .15 LA after watching an OS .10 LA
with one on youtube. (The OS 15 LA uses the OS 10 FSR/FP header).
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Old 02-02-2010, 06:23 PM
  #46
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Default RE: OS .15 CV-A question.


Quote:
ORIGINAL: Trinut

Tower hobbies has about the same pipe if you like to order from them. Just search MAC's products
It's the mac's tunned pipe 2.5 .10/.15 - about the same price. I bought one for a .15 LA after watching an OS .10 LA
with one on youtube. (The OS 15 LA uses the OS 10 FSR/FP header).
Ya, I found that farther down the Google search after I posted. Tower must have cut payments to Google to be at the top of the search results
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Old 02-02-2010, 07:46 PM
  #47
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Default RE: OS .15 CV-A question.

67S..A tuned pipe is a pretty big expense for what you get back in return. If you have a definite goal that can't be met any other way, then there you go. Otherwise, the CVA will run pretty good in a speed application with open exhaust and any kind of pressurized fuel system.
If you want more rpm for a 3D prop like a 8x3, someone else like Andy should know.
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Old 02-03-2010, 06:21 AM
  #48
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Default RE: OS .15 CV-A question.


Quote:
ORIGINAL: combatpigg

67S..A tuned pipe is a pretty big expense for what you get back in return. If you have a definite goal that can't be met any other way, then there you go. Otherwise, the CVA will run pretty good in a speed application with open exhaust and any kind of pressurized fuel system.
If you want more rpm for a 3D prop like a 8x3, someone else like Andy should know.
wanting to go for some speed with this one and put it on RaineDaves SureShark XV kit that I have.
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Old 02-03-2010, 12:22 PM
  #49
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Default RE: OS .15 CV-A question.

In general full piped 2 strokes will lay flat unless the exhaust timing is brought up to 180. To get there from stock you need a very fine carbide rotary file and a dremel. The work goes very quickly, so you need a scribed line to work up to. Take a look at the piston's position in the liner to traverse 180 degrees and depth mike that spot, then transfer that dimension to the outside of the liner to give you a line not to grind past. Deburr the cut, but do not chamfer it, you want an instantaneous open and close. Reassemble and double check your timing, from here fine tuning can be done with .002" brass liner shims. The closing edge of the crank can be moved back to 55-60 ATDC if it isn't there already. There is extra material inside the piston that you might want to remove. Grains of weight add up when the piston is doing 500 BPS.
The key now is to get a prop that will put the engine into that hypersonic happy zone, to make all this worthwhile. Eliminator props should have something in the 6.5X5.5 or 6X6 range that a speedplane could take full advantage of. You need to establish some kind of target speed based on rpm, prop and air frame before you start cutting chunks off the header for tuning the system.
To give you a rough idea, I have a stock CVA with open exhaust that does 130 mph in the mid to upper 20,000 range. If I went to the trouble of piping and did the engine work to raise the bar to 145 mph, the rpm would need to increase by almost by 8000......knowing full well that the engine wont turn much more than a big "1/2A sized prop" now to get there.
So........I can either run a stock CVA all day at 130 with a $4 prop, cheap plug and sport fuel, or go the exotic route with an extra $100 worth of stuff to gain 25% more power and gain maybe 10% more spend if all works out well.
The higher potential speed set up would be much trickier to launch, too.
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Old 02-03-2010, 05:11 PM
  #50
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Default RE: OS .15 CV-A question.

its the timing that makes the cvx engine really get up and spin, the carb helps as well, please dont run the cvx with any thing more than a 6.5 diameter prop, its just lugging down the engine, this was so common with alot of small engines, guys throw big lumber on them and then complain about overheating and sensitive needle settings, the 2f or even the 2d carb are good. 2d carbs are common and cheap on ebay, they are used clear up to the .32 f engines which on helicopters are spun at 19-22 k all day long
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