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

Cermark F-16 First Flight

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Old 04-03-2006, 08:55 PM
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MattyC-130
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Default Cermark F-16 First Flight

I flew my F-16 this past weekend for first time. It has an OS BGX 1.08 Robart spring airs and smoke system. It flew great but I was a little dissapointed with the engine perfromance. I am using an APC 12X8 prop with 15% fuel. I am thinking about getting a Jet Stream muffler to help with performance. Other than changing engines does anybody have any advise on getting my 1.08 to perform like I think it should?
Here is a link to a picture of the aircraft.

http://www.columbiarcflyers.com/phot...7&limit=recent

Thanks in advance for the advise.
Tom
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Old 04-03-2006, 09:34 PM
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soarrich
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Default RE: Cermark F-16 First Flight

ORIGINAL: MattyC-130

I was a little dissapointed with the engine perfromance. I am using an APC 12X8 prop with 15% fuel. ..... anybody have any advise on getting my 1.08 to perform like I think it should?
What disapointed you? How do you think it should perform?
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Old 04-03-2006, 09:57 PM
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Default RE: Cermark F-16 First Flight

OS 1.08 is a darn nice engine. I have two of them and totally reliable but i would not consider installing one for any propjet. Jett 90 would take it easy.
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Old 04-03-2006, 11:02 PM
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Default RE: Cermark F-16 First Flight

I dont know about that cyclic, but I'd be interested to see what rpm the 1.08 can pull with a 12 X 8..I was thinking of breakin my 1.08 in with that prop and then if the rpm hits the region I'm aiming for run a 12 X10 or maybe even a 12 x 12.
I dont like the OS mufflers I think they strangle the engines unfortunately.

I have a OS header pipe so I can mount my mac's pipe. Hmmmm.. might be a little project for this weekend ..she how close to advertised 16,000 I can get...dont really care if the engine is happiest at 12,000, all I want is top end rpm. The only other factor worthy of consideration is the weight of the engine..it is kind of beefy for a 1.08 size
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Old 04-03-2006, 11:17 PM
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Default RE: Cermark F-16 First Flight

Oh, theres no doubt it can pull the plane but what about top end speed or an rpm overkill on the engine? Plus isn't it a bit heavy
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Old 04-04-2006, 01:13 AM
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Default RE: Cermark F-16 First Flight

you can sometimes muster more speed with less rpm but more pitch..as for longevity of an engine..well that topic can be subjective... I dont mind burning an engine up, say if I get 5 years of fast flying over 10 years of moderate speed
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Old 04-04-2006, 10:16 AM
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Default RE: Cermark F-16 First Flight

put more prop on the engine. The 12x8 is pretty light, and although the OS will turn decent rpm..... its got better power around 10000 - 12000 rpm. With a stock muffler, it is not going to seriously unload in the air. What you see on the ground is about what you get.

Try a 12x10 or 12x12 on it for starters. Should help with the speed. Experiment a bit.

Crazy4Flight can tell you a bit about his GP F-4E Phantom with the Jett 120 on it. Lots of power, turned lots of prop, but its just not going to unload. The OS108 runs similar.
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Old 04-04-2006, 11:53 PM
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Default RE: Cermark F-16 First Flight

Hope you're not flying off grass with that F16. I could not take off with the 12x6 prop on my F16 from grass. I also have the OS 108 and noticed that it weighs quite a bit more compared to typical 90 size stuff. Wonder how much dead weight you put in the tail to balance. That will affect performance too.
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Old 04-05-2006, 09:01 AM
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Default RE: Cermark F-16 First Flight

Tom,

just of info, if you add a Jett-stream muffler on the OS108, it will help performance a good deal, but its not going to drive the rpm up all that much. You will still want to prop the engine to run in the 11.5K - 12.5 K rpm range.

As for grass ops, lots of folks flying the F-16 on grass. At least 6 I know of, 2 of those with OS91 power. From all reports, no real issues - about 150-200 feet of take-off roll

Photo here is a Jett90LX powered one, with 11x8 prop.
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Old 04-06-2006, 10:23 AM
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Default RE: Cermark F-16 First Flight

Hey Matty, I put the Long EZ in the club room for you when you get out there.

Ed
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Old 04-06-2006, 01:50 PM
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Default RE: Cermark F-16 First Flight

Agree with Bob27 put at least a 12x10 on it
WW[8D]
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Old 04-27-2006, 08:31 PM
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MattyC-130
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Default RE: Cermark F-16 First Flight

Experimented with several props and new Jett Stream muffler today these are the
results.
The Jett Muffler is obviously tunned for the larger prop. Will try the 12x10
and 14x8 on my F-16 tomarow. Tested with 15% cool power, OS A-5 plug, APC props

OS Muffler Jett Stream Muffler
12X8 13k 12.5k
12X10 11.5K 11.7K
14X8 10K 10.5K

Not quite the performance boost I was hoping for but boy it sure does look alot better than that big ugly OS muffler!
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Old 04-28-2006, 08:53 AM
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Default RE: Cermark F-16 First Flight

ORIGINAL: MattyC-130

Experimented with several props and new Jett Stream muffler today these are the
results.
The Jett Muffler is obviously tunned for the larger prop. Will try the 12x10
and 14x8 on my F-16 tomarow. Tested with 15% cool power, OS A-5 plug, APC props

OS Muffler Jett Stream Muffler
12X8 13k 12.5k
12X10 11.5K 11.7K
14X8 10K 10.5K

Not quite the performance boost I was hoping for but boy it sure does look alot better than that big ugly OS muffler!
Looks like its performing fairly well. The 12x10 is running pretty much in the band I suggested. Seems like even that you may want to go up in prop a bit more too.

That 12.5K rpm number you see there is pretty much the top of the tuned range. The engine was basically running "on the governor" at that point (tuned exhaust can actually limit top end rpm as their effectiveness drops off). Way too small of a prop in that case.

Engine performance is in part determined by how the engine is run-in and set up. The OS108 engine and jett-stream combination you have looks like it wants to be propped to around 10,000 to 10,500 ground peak rpm. A 12x12 or 13x10 would be my suggestion. The 12x10 will be ok too for starters. Either of those should get you into the sweet spot, and will still permit the engine to unload a bit more in the air. With the 12x12 my guess is the engine will unload another 500 rpm in the air. With the 12x10, its already running a bit closer to the top of the range, but should also unload another 300-400 rpm or so.

Keep in mind, that with this engine and 13 or 14" props (or very high pitch smaller props), an rpm boost of 500-700 rpm or so is the result of a BIG increase in horse power.

Let me know how you make out.

Bob
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Old 05-07-2006, 08:49 PM
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MattyC-130
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Default RE: Cermark F-16 First Flight

F-16 Update:
Flew my F-16 with 12x10 APC. Flew better, but I still think that the engine is just not right for this airplane. I bought a new OS91FX engine and ordered an Ultra thrust mufflers for it. This engine is a lot lighter than the 1.08 and hope it will be the right combo. I plan on running APC 12X8 on it, any sugestions on prop size for the 91FX would be greatly appreciated.
Thanks,
Matty
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Old 05-07-2006, 09:18 PM
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Default RE: Cermark F-16 First Flight

I have a OS .91FX in mine and use a 12x8 prop. The 12x8 seems to work good.
Tried a 12x6 and a 12x7 but not enough pull,just high RPMs.

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Old 05-19-2006, 09:30 PM
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Default RE: Cermark F-16 First Flight

Put in the new OS 91FX in the F-16 turning a 12X8 prop at 12k RPM with stock muffler and 13K with Ultra Thrust. Flew OK with stock muffler should fly it this weekend with Ultra Thrust, performance should be much better.
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Old 05-20-2006, 01:47 AM
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Default RE: Cermark F-16 First Flight

WOW just got up to speed on this thread... A 91FX, I would prefer the ST G-90 to the OS but it sounds like it is working for ya... I would get rid of the stock muffler if you have a U/T or jett-Stream for it-

The 12x8 is much better on the 91 than the 1.08

Last option is sell the 1.08 and the 91FX and put that towards a Jett-90... Aren't you always gonna wonder what it'd fly like with the SJ-90 on board?

Keep us posted on the UT numbers---
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Old 05-20-2006, 05:41 PM
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Default RE: Cermark F-16 First Flight

DONT HAVE THE FIRST FLIGHT BUT TOMORROW WILL BE THE ONE , I PUT 1 INCH BIGGER RETRACTS ON IT ,CANT STAND A PLANE THAT WONT STAND UP HIGH ENOUGH BUT IT WORKS,,,, JUST HAVE A LITTLE BIT BIGGER HOLES IN BOTTOM AND THEY LOOK GOOD FOLDED UP (CAN SEND PIC`S IF YOU NEED TO SEE )AND CAN CLEAR A 14 IN PROP BUT SINCE IM USING THE OS 90 IM GOING FOR A 13X8 ,IT WILL BE THE ONE FOR POWER ,-----I DO HAVE A QUESTION THOUGH THE BALANCE POINT FOR IT IS WHERE ? 8 IN FROM WHAT THE CRACK IN THE EADGE OF WING I HOPE ,,IT FEELS GOOD ,,,IF ANYONE READS THIS PLEASE CONTACT ME AND CONSOLE ME ON BAL POINT I DIDNT GET DIRECTIONS WITH PLANE ,@ BONEHEAD2434@INSIGHTBB.COM,,,,, THANKS GUYS
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Old 05-20-2006, 08:45 PM
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Default RE: Cermark F-16 First Flight

Flew the F-16 today with the new ultrathrust muffler, WOW, performance is awsome like a different engine. Speed and vertical with the 12X8 APC is awsome. I think I finally found the right engine set up for this aircraft. Will put the 1.08 in a Rear Bear.
To recap Cermark F-16 with: OS91FX, Ultrathrust Muffler, APC 12X8, 15% Cool Power, OS #8 plug. Robart Spring air retracts and Macs simple smoke system.
I am giving these details so somebody else out there may not have to go through all the trile and errors I had to go through.

One question, when I turn on the smoke the engine seems to richen up and lose about a 1k RPM. I am thinking this is because of the tuned muffler, i.e. some of the smoke fluid is resinating back into the piston. Is there anything I can do to fix this or do I have to live with the RPM loss with the smoke on? I do have a remote mixture control but hav'nt tried leaning it with smoke on.
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Old 05-20-2006, 08:55 PM
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Default RE: Cermark F-16 First Flight

8" back will be good for first flight, maybe a little nose heavy. Make sure you have some positive incidence when it is sitting on the ground or else it will be a bear to get to rotate for take off. My first flight it was nose heavy 8" CG and 0 positive incidence I ended up with full up elevator to get it to rotate and almost ran out of runway. Lengthend the nose gear about one inch and solved that problem. With the 91 in it instead of the 1.08 the balance point is about 9" back which seems to be perfect for my taste.
Hope this helps
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Old 05-20-2006, 09:15 PM
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Default RE: Cermark F-16 First Flight

thanks ill give it a try!
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Old 05-21-2006, 08:30 PM
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Default RE: Cermark F-16 First Flight

Any pics/info on the smoke system? I am looking at putting one on my -16 but am not sure if it worth the money or extra weight. Thanks
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Old 05-22-2006, 07:37 AM
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Default RE: Cermark F-16 First Flight

Matty,

I'm pleased to hear you now have the performance you were looking for, and that the plane flys well

I would be VERY careful pumping smoke fluid into a tuned muffler. There is a chance that the fluid can be ingested into the engine during the return-pulse.

The other reason for drop in rpm, is you now have additional material entering, and then trying to exit the muffler. That will create additional back-pressure.

Bob
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Old 05-23-2006, 02:50 PM
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Default RE: Cermark F-16 First Flight

Bob, Thanks for the info, I am going to try to tweek it a little to lower the amount of fluid being injected into the muffler.

Boomer, I use the Macs simple smoke system. It works great I even have it on my patriot and F-4, 40 size aircraft. cost is about 25 bucks and here is a link to it:
http://www.macspro.com/smokesys.asp
I think tower hobbies also carrys them. I use 1/2 super dry smoke fluid, 1/2 diesel and one small bottle of 2cycle oil(made for 1 gallon at 32/1 mix). Weight is negligible, servo, tank, valve/tubing. Do it, you will love it. The tank is mounted right behind the fuel tank under the canopy. You do have to drill and tap the backplate on your engine for the pressure fitting. I will add some pictures when I get home
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Old 05-23-2006, 03:22 PM
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Default RE: Cermark F-16 First Flight

Thanks I look forward to seeing them.
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