troposcuba

ok, just acquired a fun 51 for free!! can't beat that. i downloaded the instruction booklet. it was already built and in need of some repairs. those are done. problem is that there is no measurement for the balance point in the instructions. it tells you to hang it from a string through the hole in the fuse at the balance point. well since the builder didn't include this hole and i don't have the blueprint, i was curious if anyone knew exactly where i should locate my CG.??? I really wanna fly this thing this weekend, so please someone hook me up.

thanks for any help ahead of time.

JPMacG

My Feedback: (2)

As I recall the balance hole was pre-drilled in the fuse parts. Maybe it is hidden by your covering. Try to feel for a hole.

I'll check mine toinght and see where it is.

flightcrazed

My Feedback: (13)

I think it's pretty close to the spar... If I have time I'll check my plans and measure from the LE..

troposcuba

I thought that and felt around. i didn't feel one, but that is not to say it is not there. maybe i will pull back the covering to see what i can find. thanks.

JPMacG

My Feedback: (2)

The balance hole is 3 and 3/4 inches behind the leading edge of the wing, as near as I can measure.

troposcuba

cool thanks. i will letcha know how the first flight goes when i get a break in the weather.

troposcuba

ok, more specifically to be sure we are talking about the same location... where is the balance point (hole) in relation to the wing spar? mine balances about on the center of the wing spar setup as you see here. here's some pics of the plane and the repairs i did. pay no attention to the ugly epoxy booger at the wing root. that was already there when i got the plane. i added the aluminum plates and made the landing gear. the gear is an exact copy of the one that was on the plane when i got it only not tweaked like the origional. i made mine out of .100" 2024 T-3 aluminum. scrap aircraft aluminum from work. I also made the exhaust pipe from some copper elbow from the local hardware store. without it, it made a mess of the wing and servos. hopefully this little exhaust diverter will help a bit. if there is good weather this weekend, we should have the maiden flight report then.

flightcrazed

My Feedback: (13)

Mine is right on the spar as well, I dont have an exact measurment, sorry I didn't get back to you sooner. I was wondering how you worked the copper elbow with the hose clamp?? I tried a few different things with copper 90º elbows, never had too much success.. I hope you have better luck. I have just givin up and use a lot of glass plus..LOL

JPMacG

My Feedback: (2)

My balancing hole is 0.35 inch behind the rearward edge of the wing spar. The spar is hard to find as the sheeting goes past the spar. I measured through the servo hole. I expect if you balance it on the rear edge of the spar it will fly OK and you can move the balance point back from there as you get comfortable with the flying characteristics. Nose heavy is certainly better than tail heavy.

Your Fun 51 looks real nice - makes me want to fix mine. I had a good time with it for two years but finally after uncountable bad landings the fuse cracked at the wing leading edge. I decided to retire it as I thought the repair would be heavy. I used an Enya 45SS and that was enough power for unlimited vertical. I could not get it to do a decent hover, seemed like it needed more rudder, but maybe that was my limitation. It would do a great inverted flat spin while maintaining altitude.

It was my windy day airplane. I enjoyed watching it fly backwards, and it handled well on gusty crosswind landings.

troposcuba

no worries, the copper elbow i just cut a bunch of slits in the end that i put on the muffler and clamped it with an automotive type hose clamp and cranked it down real good. haven't tried it yet, but it should work. even if it falls off it should just drop off the back hopefully. but i seriously doubt it is going anywhere i couldn't yank it off during the "yank on it test".

troposcuba

.350" behind the spar?? so just a hair over 11/32". sounds like i am close. mine seems to balance right about the aft edge of the wing spar. so it sounds like i don't need to make much for adjustment for now. i can play with it later as i get familiar with this plane. Mine is only partially sheeted on the leading edge. it stops a couple inches short of the main wing spar. so there is a difference it sounds like.

this is my first sport plane so it should be interesting. i flew some pretty high performance slope gliders for about 10 years and have been flying the coating off my alpha 40 lately. i have also flown several of my friends planes (funtana, somethin extra and a couple spads) the guys that i fly with are tellin me that i am ready to fly this fun 51 and i feel confident so weather permitting, i am gonna give it a go next weekend.

thanks for the info and help.

daven

My Feedback: (1)

The starting throws are fine once your use to it, but may seem pretty sensitive for the test flights and trimming. I flew the heck out of my Extra Special which was basically the same plane. Does very good inverted climbing flat spins.

troposcuba

well she flies. a little interesting on the first takeoff, but managed to pull it out after a couple wild moments. put 5 flights on her today. the (free) engine that came with the free plane is worth about as much as i paid for it. 4 flights ended in deadstick landings (I did run it out of gas once though) and only 1 under power. landed on the wheels every time and flipped over really gently in the super soft sand/grass of the surrounding beanfield one time. no damage though. so tomorrow i am gonna try a couple different props to see if that engine likes something else better. but all in all a good day. she sure flies nice when the engine is running. actually glides fairly well on the deadstick approaches as well. so i guess we can call today a success. actually i am sure we can call it a success. no damage is a good day no matter how you look at it.

flightcrazed

My Feedback: (13)

Sweet! Glad to here it was a success!![8D]

troposcuba

alright here's the update. i went out again sunday. couldn't get the engine to run reliably enough to even put it in the air this time. so we did the field teardown out of curiousity (there was a spot that seemed like a lot of bind even with no glow plug in it) the guys thought bent crank. it all appeared to be in fairly good shape when we got it apart. so I soaked all the metal parts (piston, head and cyl. sleeve) in some of that really good automotive carburetor cleaner that comes in the gallon can for a couple hours. cleaned up all the carbon and varnish off everything and was surprised to find that it was in even better shape than we thought initially. so lubed everything up really well after a thorough cleaning of all parts and reassembled. I also suspected a possible leak at the fuel fitting on the carb so that went back on with a touch of loctite (very careful not to get any into the end of the fitting). the engine turns much smoother now. it was pretty sooted up on top of the piston and in the port openings of the sleeve. anyway all said and done, fired it up and did some tuning and drove it around the yard, much to the annoyance of my neighbors i am sure, and ran a couple tanks through it with zero negative issues (well except the fact that as much as i wanted to throttle up and take off i could not! my street is not the place to fly for sure.). so i think that i will enjoy this plane much more now that i trust the engine quite a bit more. good thing is that i got plenty deadstick practice in due to an unreliable engine that first day, so my confidence in being able to fly this plane is good now. so just gotta wait for the rain to pass and I will give it another go.

troposcuba

ok another update. it flew great. had a good day with zero engine issues. last landing of the day i misjudged the edge of the runway a bit and hit the tall weeds at the edge. ripped my landing gear repairs out. flew great till that happened though. i am in the desert for 4 months now, so it will have to wait till i get back. i think i can splice in another repair and be up in the air again in no time once i get a chance to work on it.

thanks for the help provided above.

flightcrazed

My Feedback: (13)

Great to hear you had a good flight with it!! I really like my fun 51, it's VERY stable, flies really easy.

Coug Air

The landing gear is a weak spot in this plane. Poor design! The rest of it is an absolute blast though! I just add 1/8 ply over the old old fuselage on both sides. It's about three to four inches long under the wing and forward to the nose. I have been flying for over 2 years without any damage to the fuselage. I have a Magnum .52 and the takeoff roll is about 8 feet into a vertical climb! A friend has the Extra Special and so does my son. We moved the tailfeathers back two inches on the Extra Special and added one inch to the rudder. Maiden is scheduled this Saturday! We flew the Extra Special with a one in extension and it was better than the original The two inch ought to be much better! There is a HUGE difference in rudder size between the Fun 51 and the Extra Special. The Fun 51 got the short end of the stick! I may have to take a dive to wipe out my fuselage and build a larger rudder with the two inch extension!

It is a great plane for the wind. My favorite maneuver is to point it into a 15 -20mph wind and slow it to a crawl. Then I just relax the elevator and it comes almost straight down with about a 3 foot roll out! It's COOL! I did add some Goldberg profile gear so we didn't have to bend the aluminum back out from the wing sheeting!

Here is a picture of the 1 inch fuselage extension in the Extra Special without the ailerons attached. it currently has an OS 50 in the nose replacing the Magnum .46 shown here. The Fun 51 picture was when it was newly completed. The engine in the pic was an old ASP .46 that I ran until upgrading to the Magnum .52.

troposcuba

yeah, i hear ya on the lower center fuse/landing gear attachment site. that is where it broke just beyond my repair. i repair fullsize aircraft structures in the USAF. so i have a pretty good idea about structural failure points. anyway, my repair was pretty much what you mentioned about the ply. i used .050 7075 T-6 aluminum sheet with some hi-locs (aircraft grade fasteners). I spliced in a the old piece that was broken free between the plates with some 60 min. epoxy. that part of the repair held up ok, but the wood on either end of the repair did not. that was the weak point after my repair and became the points of failure. so the new plan (when i get home from this deployment) is to extend the cutout in the damaged fuse to where i have clean undamaged wood. then splice in a new piece with a thin overlay of fiberglass and then another set of aluminum plates extending a bit futher back and fwd to lessen the local strain around the gear. it is thin enough that it only adds minimal weight and it is near enough the cg that it does not affect the cg in a negative manner. can't wait to get home and to get this bird back in the air. till then it is fixing the big ones and eating in the chow hall and going to the gym every day. that is the routine.

thanks for the info on your solutions though. i may have to total the rear section just to have an excuse to upgrade it as well.

cheers

daven

My Feedback: (1)

I picked up an Extra Special as they were being Discontinued a few years ago. The price kept dropping nearly every day until they were gone. I believe I paid about $30 for the kit and had it in the air 12 days later. I flew the crap out of that plane, and recently sold it off. Did a very nice inverted climbing flat spin. If you reduced the throttle it would just spin on its own tail holding its altitude indefinately. Never liked it as much upright, not sure why. I had about 6 oz of lead glued to the tail, and it was still relatively stable on landing.

JPMacG

My Feedback: (2)

I bought one on that sale also. What a deal! Wish I had bought several. The box of balsa and parts were worth more than $30.