o,s, 32 max
 

running a new os max 32 in my little sig kobra. what is the correct prop for this engine? bought the engine new but was open box and did not include a manuel. thanks

RE: o,s, 32 max
 

I would break in with an APC 9X5 and then go to a 9X6. These little buggers have power and can handle a fair amount of nitro.

RE: o,s, 32 max
 

9 x 8 will make it happy.

RE: o,s, 32 max
 

Respectfully disagree. A 9x8" prop Will knock it down out of it's best power band (which is 16k rpm & above), and make it run unnecessarily hot (an especially bad thing during break-in).
Speedracerntrixie had the prop recommendation nailed, although it wouldn't really hurt much to skip the 9x5" and go straight to the 9x6".

RE: o,s, 32 max
 

9 x 8 is what gave the most speed on my LR-1.

RE: o,s, 32 max
 

i have one of these kits to build. i plan to use a 35 AX and jett muffler with a 8x9 prop.

For the OS 32 you can run it stock with macs full tuned pipe and 8x8 at around 17,500-18,000



The 9x8 gave you best speed on a LR-1????? which LR-1 several kits out there. also that is just to much load for the engine as C_Roundy said. I bet you had a 9x6 prop which might gave best speed if running stock LR-1 with big wheels and wheel pants.

even with stock muffler the APC 8x8 is a great prop for it.

The kobra and couger look good with a side mounted engine, full pipe and the wheels tucked up.

RE: o,s, 32 max
 

'twas the Extreme Composites, if I remember correctly.
I tried 9 x 6, 9 x 7, & 9 x 8 on stock muffler, the 9 x 8 was the fastest in a dive though it did run a bit on the warm side. 9 x 7 was fastest in level flight.
The next one (I have a new LR-1 in the box) will have my Jett 35 on it.

RE: o,s, 32 max
 

This is pretty much what I thought. The 9X8 needed a dive to unload enough to get in the power band. And this was with a clean airframe. This is the part that most guys just don't understand. It is just as important to match the prop to your airplane as it is to match it to your engine. A Kobra has alot more drag and would perform like poop with a 9X8. The airplane would just never go fast enough to get the engine to unload. With the .32 I suggested the break in with a 9X5 so that you can get into the RPM and heat range needed for proper break in. If you rush it too much it will show in a lack of power and longevity.

RE: o,s, 32 max
 

Speed racer I flew the plane 3 times with a 10 x 6 prop on it. It seemed to perform ok but was much better coming from a dive. Seemed like the motor wound up more. Found an online manuel and it said for sport flying use the 10x6. I would be more than happy to give the 9x6 a run if you think it is better for the engine. Looking to make the plane as fast as possible given what it is. Retracts and such would be nice but didn't want to sink a bunch into this little kobra. this is my return from 27 years out of RC and between this kobra and a trex 550 helicopter im having a ball. Flew pattern very little when I was a kid and the remakes of them from great planes have me salivating. that tuned pipe and screaming engine always did it for me. Thanks for the help, i'll give the 9x6 a try.

RE: o,s, 32 max
 

http://www3.towerhobbies.com/cgi-bin...?&I=LX1539&P=0 APC 9x6.5 40 pylon

this is a great prop for this engine with the stock muffler and the kobra.

run this prop with the macs pipe below.

http://www3.towerhobbies.com/cgi-bin...?&I=LX1540&P=0 APC 9x7.5 40 pylon

http://www3.towerhobbies.com/cgi-bin...?&I=LXZ558&P=0 Macs 32 tuned pipe non muffled get the muffled if need to tone it down some.

http://www3.towerhobbies.com/cgi-bin...?&I=LXZ607&P=0 OS 32 header cut to length.


Bigger i have had a few of those LR-1's all with Jett 35 LX FIRE's. here is a video. i didnt know i was getting filmed though so wasnt doing anything special. It was running a 8x7 APC at 21,000 or so on the ground.

http://www.youtube.com/watch?v=jYFfBags08M

RE: o,s, 32 max
 

I've seen that vid, the plane is smokin' fast!!
My engine is not the FIRE, it is a FISE BSE with Jett muffler.
Does that marine pipe make the engine real peaky?

RE: o,s, 32 max
 

not not at all. for the side exhaust run the 8x7 or try a 8x8 but may have to remove about 1/8th of the tips.

RE: o,s, 32 max
 

airraptor

Wow is all I can say about that video. That thing is insanely fast. I'll give that prop a try as well.

RE: o,s, 32 max
 

It takes almost 5 HP to turn a 8x7 fast enough to go 190 mph. A APC sport prop [no less] with thick, heavy blades.
The Nelson FIRE FAI .40 [which is a true 200 mph engine] only puts out 3.5 HP. It can only handle a 7x7 carbon prop with very light blades
Hmmm.....the Nelson .40 must have 1.5 times the intake area flowing through the crankshaft as the Jett .35...
Hmmm...interesting.

RE: o,s, 32 max
 

I don't see the hp requirement(static perhaps), but geessus talk about unload rpm, 28+K? The video sounds up there tho. Two of the best engines Jett ever made the 35 and the 56.

It begs the question. how long will it last?

RE: o,s, 32 max
 

Cp what are you saying? You didnt say one thing here that meant anything at all.

Sometimes you come on here looking for a fight.

in the beggining of the video you here my friend pat call out the reading on the radar gun. i made several passes for him. The video was edited by the guy filming. i assume the pass where he called out the 190 was a down wind pass. the wind was around 15-18 steady that day. So lets say atleast 170. also you assume it is a stock APC prop also.

I do have a nelson engine in a plane that can do 230 and soon to work on a electric plane that should break 250 on 4000-4300 watts.

the runway there is 500 feet long so go do some math ok quit posting crap after me or we will go to the moderators again!

RE: o,s, 32 max
 

freak you are correct the two best sport engines are the 35 LX and the 56LX.

The 35 needs the rear bearing changed out often usaully about every 5-6 gallons. The piston did break on me last month. i need to order a new rod, piston and sleeve. i have some carbon 7.4x8.5 props to try on it.

I posted that video a long time ago. I found out later that it was only a downwind pass that day. Before he always average it out for us. i say it was a 170mph plane. I have a new one that is built. It should be a bit faster hoping to break 180 with it on the Jett 35. This one has no external control linkages and i removed the left side engine cheek cowl. It also came in at 2.9-3.0 lbs minus fuel.

RE: o,s, 32 max
 

Go to the moderators then. See if they will validate your claim.

RE: o,s, 32 max
 

Dang! where did they put the popcorn eatin' smileyface?

Airraptor, don't worry, 'Pigs just bein' hisself. Its like you said, he didn't really say anything in his post that meant anything anyway; So certainly nothin' actionable.... His whole post was just one big fat poo flingin' insinuation. Nuthin' really toxic in it, just poo.......

I was really proud of the way ya jumped back at 'im tho', laughed so hard I almost blew ice cream out my nose.

Anyway I like the poor bugger, I dont hafta wake up in the morning and be him to get a lot of free entertainment from all the stuff his fingers spew outta his keyboard across the years, besides, truth be told his poo is laced with gold on occasion.

And you CombativePig, (sigh), dont ever change, jes keep yerself safe, try to be nice, and go wash yer hands mister.

Now, there's no way I can force you guys to shake and make up, but understand that if you two keep tusslin' and flingin', I am NOT gonna clean up after you!

Chuck

RE: o,s, 32 max
 

Guys, why the bickering back and forth. Isn't this suppose to be a hobby we can ENJOY? (Man do I sound like an old man!!) Thanks again for the help on the props. And to me anything over 100 is plenty fast. Air raptor I can't see how you keep track of something that small moving that fast. I would think if you even blinked your eyes the plane would be long gone at 190 MPH. Nice flying BTW.

RE: o,s, 32 max
 

Let's not start any bad vibes here guys and I didn't intend to stir the pot. As far I'm concerned, C.P., raptor and Mr. Roundy are the most proven and respected speed freaks here, each of them with numerous results that seem to break the laws of physics. How many times have I said to myself, why did that work? the math says no, yet there it is.

There are fewer of us as testosterone seem to be leaving humanity, so let's stick together.
Speed is our family bond.

RE: o,s, 32 max
 

Roundy has some really fast planes also. His delta called the slipstream is well over 210. His rare bear at 190 on a YS 170 is also a great plane. I wouldnt want to fly it because of how good it looks.


I used to live tacoma washington so i know how CP is how he is lol when in washington i would only get about 3-4 months of sun the rest were rain days.

RE: o,s, 32 max
 

Agreed, and C.P. has a huge arsenal of scratch built speed planes that could only originate from a very creative (scary) mind.:D[hr]

RE: o,s, 32 max
 

I have a Cobra (wood kit) and an LR-1 (un-flown /upgraded) that I'm not going to ever fly[&o]. Too dang small for my eyes to see.
Sticking to my deltas with florescent red on top and black on the bottom, that I can see. Sucks getting old.

RE: o,s, 32 max
 

Umm,............ Uhh,............................. Ahem,............................................. ......... Group Hug?