rcjon

I have an OS 61 that's looking for a home. To round out my hangar, I'd like something really quick to put it in (ARF).

I don't plan to race or set speed records, just something that will turn and burn enough to make pilots at the field look up and say "Dang, that thing's fast!"

Any suggestions?

Flyboy Dave

My Feedback: (21)

What model OS is it ?

FBD.

rcjon

O.S. .61 FX Non-Ringed w/Muffler

SPEED JUNKIE

My Feedback: (14)

A.R.F.- Almost Round Fuselage?
Well this might do the trick!
It's a little wobbly on take off but once in the air watch out this thing rips with an O.S. 61!
It won me several races back in the day!
(HE HE HE!)
Rev Bro #118

Flyboy Dave

My Feedback: (21)

You could put it in a World Models .45 size Mustang it would go OK....

....unfortuneatly, The OS .61 FX is kind of a dog. []

FBD.

Rcpilot

My Feedback: (78)

Lanier F-4 Phanton 40 ARF--that would move along pretty good with a 61FX.

GP Shoestring Racer 60
GP Little Toni Racer 60
TH Kaos 40
Lanier Predator--ROCKET SHIP!! with a 61FX on it.
Lanier Invader
Thunder Tiger Rare Bear

Kit:
GP Patriot-fast-fast-fast
Lanier Shrike 40--LOOK OUT!!! with a 61FX on it.
Balsa USA Enforcer
Balsa USA Force One
Balsa USA Northstar

I've had 3 of the 61FX engines over the years. They are a good sport engine. Great for general flying and there's not a thing wrong with them. There are a few other engines in the same class that may have a few more ounces of power--but I wouldn't laugh at a 61FX. They are fine engines.

They respond REALLY well to a tuned pipe. The full tuned setup is kinda spendy--but you WILL notice a big difference. You can get cheap power by simply bolting on a Macs muffler #6860. It's about $38 and will give you a few hundred more RPM.


I did drill out the crankshaft on one of mine. I did this on the engine that I had the tuned pipe on. I can't remember exactly how much I drilled it out. It wasn't a lot. Just one drill bit size bigger than the factory hole. Deburr it and clean up the intake opening with a little sanding stone on a dremel. Make it SHINY inside. That helps fuel flow.

Get a degree wheel and determine your intake duration. Grind on the CLOSING side of the intake hole in the crank and increase yoyr duration a bit. NEVER--NEVER grind on the OPENING side of the crank. You'll mess it up and the engine won't run for sh*t after that. A little goes a long way--so don't grind off more than maybe 1/16th of an inch.

If your daring- you can grind off the sleeve on the exhaust side. The exhaust port is always bigger than the opening in the sleeve. Grind away the TOP of the sleeve untill its even with the case. DON'T grind away the center vertical support in the sleeve where the exhaust opening is. Can't remember off-hand if it has that vertical support or not. Some engines do--some don't If it does--leave it alone and just grind away on the top of the sleeve untill you are flush with the case opening.

One of the carbs for the heli engines will bolt right in. It has a 3-needle setup. You can adjust the midrange. With the full tuned pipe--and a 3-needle carb--you can really get it dialed-in for great performance at any throttle setting. THAT will make it a real screamer.

They responod very well to minor mods. But don't get all crazy. Your limited by the transfer port timing--and you can't change that. You can get a better carb. from a heli. You can drill out the crank a bit for more flow. You can grind off the CLOSING side of the intake post on the crank to increase intake duration. You can grind away on the top of the sleeve at the exhaust port to increase exhaust duration.

Easiest thing to do it bolt up a Macs muffler.

Tuned pipe is great, but lots of $$$. If your gona spend the $$ on a tuned pipe--then make it worth the investment and buy the heli carb. and do some grinding on various areas of the engine.

You will be TOTALLY amazed at what a 61FX with a few mods and a pipe will do.

But still, nothing wrong with a stock 61FX. Put the Macs muffler on it and have a blast.

rcjon

RCpilet,

I think I'll try a Predator. That will allow me to use a function of my Tx that I haven't used before (v-tail mixing).

The 61 is out of the recommended engine size range. How do you think the balance will work out?

jon

Rudeboy

It will turn out VERY nose heavy...

bob27s

My Feedback: (19)

You definately do not want a 61 engine on any Q-500 airframe.... will turn out way too nose heavy. We have enough trouble getting the CG correct with most .40 engines

Rcpilot

My Feedback: (78)

I put an OS 46FX on a Predator and you would not believe how tail-heavy it was. I was pissed off--really pissed.

I had ordered an HS-81 for the throttle and HS-225 for my elevons. RX was Hitec 555 and my RX battery was a 270mah nicd.

I ended up installing a standard size JR517 right behind the firewall to get nose weight. I crammed a 600mah battery up front too.

I had to scrap the stock servo tray and move my HS-225 servos under the wing saddle and completely rework the linkages to balance my plane.

I had to shove the fuel tank so far forward--that I needed to dremel out the front former under the LE of the wing. That was so that I could get the tank as far forward as possible.

Do I think a 61FX will make it nose heavy? NO

A 61FX w/ stock muffler weighs 7 ounces more than a 46FX with stock muffler.

I don't know what to say. Maybe I just got a plane with spruce hardwood in the tail?????????

I still have a wing and tail set for the predator. I'm going to buy a fuse cheap when one of them shows up on the TH scratch & dent page.

I'll be using a 60 size engine--and I'm confident that I won't have to make NEAR as many mods to it as my first predator with the 46FX.

RCJON--I'd bolt the engine to the firewall first and then start placing servos and other electronics in the plane. Find out where your servos, RX, battery will need to be located to balance it. You might have to make a few mods--might not. But--definetly bolt the engine up first and balance from there.

GLASS and PIN the firewall--DEFINETLY. Add tri-stock and slap some epoxy on there to coat it all and add strength.

Good luck--and for gawd sakes --put a radar on that sucker--I want to see some big numbers!!

HighPlains

My Feedback: (1)

The OS is rated at 1.9 HP @ 16K

If propped correctly, it should be able to do about 140-145 mph

I would try a 9x9 APC sport prop.

As far as balancing, have you guys ever done weight and balance calculations? Much easier than just mounting the gear into the airplane and being surprised later.

bob27s

My Feedback: (19)

The calculations work ok if you know what everything weighs But, yeah, that is the place to start. Balsa density on some aircraft can make a big difference. Nothing like having rock-hard stabs .... that can really mess you up.

The predators I have built came out nearly right-on CG with a TT40 up front - nothing extraordinary. Only minor adjustments to get the CG to 2.8" (what I prefer it). I'd be pissed too if it was that far tail heavy... something was definately wrong.

My newer Q-500 designes have a nose that is nearly 1.5" shorter than the original design in 1985. Difference in weight from a K&B.40 to a ABC 428 engine was pretty dramatic. As it is, all of the servos are aft of the wing saddle. At this configuration, the battery location can be used to fine-tune the CG and accomodate anything from a baseline 428 AAC engine, up to a TT40, and down to a .30 size engine (requires a heavy-hub, but thats all).

HighPlains

My Feedback: (1)

It's rather stunning how heavy of balsa is used in some kits and ARF's. I had one kit of a Stik that had 18 lb density wood, not the kind of stuff I would normally use with a triple beam balance gram scale. Six to eight lb wood is what I try to use for most construction. The stik will likely need the bathroom scale with the 18 lb stock, wood that the Navy rejected for rafts.

I usually put lead into the rear crankcase cover if I am tail heavy (rare).

Flyboy Dave

My Feedback: (21)

Now, there's a good idea.

Personally I wouldn't put a 60 in a Quickey, but each to his own.

FBD.

Rcpilot

My Feedback: (78)

Yeah, but it's kinda hard to send the thing back to TH once you hack it up. I got it balanced.

First flight--I had it revved up to full power turning a 9-6 APC on the 46FX with a tuned pipe at 15,800RPM. My friend gave it a shove just slightly to the right---as we were trying to compenstae for left engine torque.

Plane straightened out and got airborn after about 20' and then a gust of wind slapped the tail around and slammed me into one of the pilot safety fences.

Ruined the fuse. Saved the wing and tail. Sold the engine to a guy who absolutely loved it with the ringed heli piston and sleeve that I'd installed in it. Sold the servos for almost nothing.

It was a sting that hurt pretty bad. I spent WAAAAY too many hours making that plane balance just to see it get 3' off the runway--and then get smacked by a sudden gust of wind and weathervain into a fence. I sold all the useable stuff and stored the wing and tail in the rafters.

Maybe someday................