wjcalhoun

S&S and Airraptor
Thanks for the OS data. My engine only has about 3/4 gallon of fuel through it so far, so I'm keeping her a bit rich. It spits oil onto the tarmac, so I know it is rich. HS needle is leaned to within a 1/4 turn of optimum, but the LS needle is still way rich. Next time out I'll progressively lean out the LS needle looking for better WOT. BTW, the LS needle DOES significantly affect WOT function. I had an exchange with the OS folks that confirmed that concept.

I know the engine will do better, because I have the same engine on my 1/4 scale extra; it swings a 16x8 at 8700. I am at sea level so the air is dense.

Slow and Steady

WC,

Thats interesting to hear about the low end needle effecting wide out throttle. If the low end needle is no were near the orrifice when openned up, how can it effect the high end? May be thats why my high speed needle wasn't very effective at leaning out the engine. It seamed to take at least two gallons to get it fully broken in. Does fly great now. Would think about readjusting both needles, but hate to take a chance on messing up its current performance, though it does suck up fuel at full throttle.

Slow and Steady

Have a new issue. Plane has alot of vibration at full throttle - blew out the throttle servo on last flight. As always I ran the OS 75 AX dry after my last flight. Had to hold the control rod by hand and it vibrated like crazy, hurt to hold. Don't know if its rear bearing or loose connection somewhere in the fuselage. With the prop horizontal and holding the tips, moved them forward and back, there is a clicking sound. Remove the cowl and can't find a loose joint. Doesn't appear to be in the engine??

jet22b

SAS,

Check the prop and spinner back plate for balance!!! If you have a prop balancer, mount the prop that you are flying with and see what blade is heavy, than take fine sandpaper and sand the back of that blade to balance the prop. Use the same tool on the spinner back plate. If the backplate do not move, it is in balance, but if it do move, it will move to the heavy side. Use your Dremel tool on the spinner backplate, but be carefull on how much you take off. Grind and check until it do not move. Out of balance props and spinner will also cause vibration!! Plus the engine run better with everything in balance!!!
Please let us know the outcome!!!
Have a great weekend of flying!!!
Off to my local hobby shop to buy fuel. Just check my fuel locker and I am out!!! I just hate that!!

Sonny
aka
jet22b

microdon2

My Feedback: (47)

S&S - I agree with Jet22. But before using fine sandpaper I use a file - takes off more prop material. Then use the fine sandpaper to smooth it out. I balance all of my props now - it's amazing how out of balance some of them start out. Guess I need to check my backplates, too.

Mike

jet22b

Thanks Mike, I forgot to say first than use the fine sandpaper to smooth it out!!
Just FYI, both spinner backplate was out of balance!! So check you spinner backplate!!!
BTW; I did get the last 3 gallon of fuel at my local hobby shop. I was lucky!!! He had 30 gals yesterday and I got the last three!!! "WOW!!!!

Sonny
aka
jet22b

Slats!

My Feedback: (1)

I really disagree with using sand paper. Clear Lacquer spray (bad spelling I think) works great and you can't see it, spray it on the light side. let it dry and spray some more if needed. I do this on everything from the 23 inch for the 50 cc to the 14 inch....

Some people also balance the hub of the prop and the spinner, agian DO NOT file. Put a piece of velcro on and add ca it takes little to balance the hub and spinner. .

On smaller props the hub & spinner usually doesn't matter but worth checking.

Heres a great video

http://www.thunderboltrc.com/tutoria...ial_three.html

jet22b

Slats;

Great info!! Thanks for sharing!!!

Sonny
aka
jet22b

Slow and Steady

Thanks guys, but I have been balancing my props for at least 3 years now, and like Slats I use laquer. I also balance the hub. The way you find the heavy side of the hub, is after you balance the blades hold them horizontally on the balancer; I use a Great Planes magnetic balancer. After holding them level, rotate the prop 180 degrees. If one side of the hub is heavy, the prop will turn until the heavy side is on the bottom. The prop usually will not stop level, one blade will be alittle high. But now the light side of the hub will be on top. Usually it is alitlle off center. I add weight to the light side of the hub using small square pieces of paper towl CA's to the hub, until the prop will be stationary no matter were the blades are. I also buy after market cones for the balancer, I think dubro sells them. They have a steel shaft and are threaded. I normally do 3 props at a time, so I can check each one as the other two are drying.

Never have checked my spinners, but they are Tru Turn and should be roughly ok. The vibration didn't start when I changed props; the prop was in use for a couple dozen flights, with no problems. I appreciate the suggestions and will likely swap out the 75 AX with another one I have, to see if it makes a difference. I have a feeling it is the rear bearing and hate to tear the engine apart to find out!

Thanks again. Any other suggestions would be appreicated.

wjcalhoun

Hi Guys

I had another little issue today. Was in a power descending turn, positive G, near WOT, so a reasonably high stress maneuver, admittedly. I heard the low buzz, and saw my R aileron futtering. Immediately pulled the power to idle, circled to lose altitute and get into a landing pattern, and had to go to high rates to keep control. Fortunately I did have enough elevator and aileron on high rates to maintain directional control. Got her down without further damage.

Fortunately the plane itself was not damaged, but a control surface flutter is often times the initiating event for catastrophic airframe loss. I was fortunate.


On inspection, the nylon keeper, that purportedly holds the forward end of the aileron linkage (the 'L') into the servo horn, had come out, the linkage disconnected in flight, leaving the aileron to flutter.

I generally do not use bent rod / keeper for anything bigger than 46 size, but the assembly manual indicated it should be OK, so I used it. Again, it was my error for not trusting my own judgment on what was an acceptable means of making a linkage. But really, ask yourself - how many 'L' bends do you see on 50cc gas planes for control surface linkages? ZERO

I just installed solder clevises tonight bilaterally, so it should not happen again.

One more thing to add to the cliff notes version - make sure that both ends of all control linkages are strong. 'L' bends with keepers are not adequate. I'm thinking a 'Z' bend would also be OK, because they cannot come out, but a solder clevis or ball link is more positive.

It is just not clear to me why GP recommends 'minimalist' building approaches when most users are pushing the performance envelope a bit.


Good flying!
Bill

microdon2

My Feedback: (47)

wjc - glad to hear you made it down in one piece. Agreed on questioning the minimal approach of GP.

S&S \ Slats - I like the lacquer idea for prop balancing - makes a lot of sense. And that balance video was good, too.

mike boxtall

Have about twenty flights on the revo saito 180 combo. The motor is still running really rich especially in the low end. But it is amazing. Speed is pretty close to my little revo 75AX combo on a 13/7. It covers lots of ground really fast and tracks very very well. Just wish I could get out more. Going once a week sucks! First flight I spend re learning everything. The upgrade to a 24oz tank for me was a good idea. First few flights 7 mins and almost empty. Now after 4 jugs and leaned considerably rpm/9650, prop 16/8 apc, fuel 15% two stroke and flight times are around 12-15 min with fifteen cranks still in the tank. Really happy. No landing gear issues yet... But also no rough landings yet either. And most importanly is that the wind has very little effect.

Slow and Steady

Sounds great Boxtail!

jet22b

Nice flight report, Mike!!! Just this pass weekend, I was the first one at my club flying and the last to leave!!! I would love to put lights on her and fly at night, but the club rule is no flying before 10:00AM and no flying after 9:00PM. Yes this plane is a joy to fly and I have a blast with them!!

Sonny
aka
jet22b

airraptor

My Feedback: (66)

slow they say 9500 but i run my faster than that. if you run a 16x6 APC in the air like on the revo it will be over 10,000. for your larger revo the 14x10 or 15x9 would be the best choice. the 14x10 for speed.

pryor808

My Feedback: (1)

Hey! Guys,

I am back into this thread due to me having problems landing this great plane. The only time a have great landings (greasers) is when there is a 10 mph headwind or a dead stick. If it's a very calm day, oh! boy..this plane floats in and, will want to keep flying. I have the idle on my 91FX (14x6 prop) as low as I can get it without dead sticking the darn thing. The plane is balanced a tad nose heavy but, that's my flying style. If I change the CG a little bit aft, she flies like crap (dangerous). it's either great dead stick landings or windy day landings. Are all of you experiancing the same problem?

jet22b

Hey pryor808;

What I did to help me land the 70" Revolver was to see how slow I could fly the plane before it stall!! I found out that this plane can fly very slow before it stall and that's with full up elevators. After that and for the next 5 tanks of fuel, I did touch and goes untill I found the right approach speed and angle. For me as soon as I am on the downwind leg, engine goes to low idle and stay that way. One thing you will find out with this plane, is when the nose point down the speed will build up fast, so stay off the power. My club field have very tall grass at both end of our 366 feet grass runway. I have my plane just above the tall grass on final and very flat to bleed off the speed. With no wind, she land in about 20 feet from the approach end of the runway. Now with wind, I do have to play with the throttle a bit to keep it out of the tall grass. Like you-self, my three Revolver is a tad nose heavy, ( I also like it that way!! ). Now I can spot land and be happy. Try doing just touch and goes to get a good feel of this plane. I hope this help you with landing this bird.
Well the weekend is almost here and I will be at the club field flying something!! I try very hard not to take the revolvers, but they find their way in the back of my Ford Escape!!

Sonny
aka
jet22b

wjcalhoun

The airframe IS pretty clean, so it does pick up speed on descent, and because mine is on the heavier side (9.5#) tends to carry speed well, and because of the larger than specified engine/prop, it likes to keep flying. I set up high/low idle by mixing throttle-to-throttle on a switch, so my flying (hi) idle is secure at about 2900 rpm, no problem with dead stick or loading up, but my lo idle is about 2400 rpm. Makes landing more straighforward, regardless of headwind. I'm not sure the engine would idle for 3 minutes on low idle, or if it did, probably would stumble a lot when opening the throttle, but the low idle setup has been a nice addition.

Slow and Steady

While I fly mine now with a 75 AX and 13 7 APC, I started out with a 91 FX and a 14 6 APC. I had a very good IMAC flyer try it out with the 91 FX and he brought it in with almost no roll out (30' on the runway between touch down and stopping); I can tell you I was very impressed by his skill. While I do not have that skill level, it is never more than 100 feet even without a breeze. You may just need some practice. This plane doesn't fly like the Revolver 46 and should be an easy lander, especially with the oversized main wing. That being said, if it is nose heavy, it will have a tendancy to pick up speed on the descent. However, with a good idle, 1500 rpm, the 14 6 should act as an air brake. Good luck!

Luchnia

My Feedback: (21)

Why did you go to a 75AX with 13x7 when you had a 91FX on the plane? I am curious as to the what the objective was of changing to a smaller engine.

nh4clo4

My Feedback: (33)

Asmaller pitch prop also works well. Itried a 14-4. on a 91 4stroke. it didn't have the top end, but the landing, slowed right down, and stopped in about 30 feet. with the 14-6. performance is considerably better. But requires a little different approach. You need to cut to idle quicker, and Iusually use a larger diameter final turn.
With the 14-4, It landed like a 40 size plane.

Also Mine is at 10 lbs, where some of you guys are at 9.5.
ED

Slow and Steady

The 91 FX had bearing issues and I had a 75 AX laying around. Both fly about the same (similar speed), but there is no airbraking with the 75 and 13 7. You may be interested to know, the IMAC flyer I mentioned, thought the 14 6 prop was to large and overpropped the engine; he didn't elaborate, but you may want to try a 13 8, when you get a better handle on the landings. Some in this blog have noted that Great Planes was off recommending the 61 to 75, and they may be right about the 61, but the 75 has great speed and flight characteristics on this plane, I thought the 91 was also a good choice, as may be the new 95 AX. These engines with a Bisson pitts muffler have great power and keep the weight down, which is probably enhancing the overall flight performance.

Luchnia

My Feedback: (21)

I recently put new bearings in my 91 FX and the RPMs are tight now. I can get to around 12k. I have only flown my larger Revolver about 6 or 7 times now and so far not too many problems. The only problem I have is with my 91FX. It has some idling low end issues. If you let it idle for a bit it gradually idles down too low and if left long enough will die out. I have had it apart and checked it out but really found nothing wrong at all. I do have decent transition now, good full power and high RPMs around 11k to just under 12. At first I had a couple dead sticks but have only since been flying smooth patterns and so forth to get everything dialed in like I want.

It has a 14 x 6 and seems a great combo and it seems to slow down extremely well and lands rather gracefully. I would really like a bit more speed since I am used to the way the smaller Revolver screams around the air. As I get more proficient I may try a 13 x 8/9 to see how it does. That might just be the ticket for this plane.

This 91FX has dead sticked with me a few times in another plane and I am just making sure I have it tuned good and running strong before I do any wild maneuvers. I did a quick snap the other day and dropped the throttle and started straight up and when I did ithe engine died...there is that low end issue again. Fortunately I was up high enough and was able to bring it in with only minor damage to repair.

I simply hate to mess up a plane over some crapola-running engine. Pilot error is one thing but a half &$%)& engine is another issue of its own. [X(]

wjcalhoun

Luchnia

Is the engine new? If so, the low end idle may smooth out a bit as it breaks in. I'm sure you have tried leaning the LS needle bit by bit. You might try the high idle / low idle on a switch idea; keeps your flying idle (high idle) high enough that there is no chance of dead stick, but the low idle is low enough for you to get slow.

pryor808

My Feedback: (1)

Ok! Now that we are talking about the 91FX..I can tell you that engine is one of my favorites but, there is 2 of them. The old and new. The old 91FX has the remote needle valve holder that is part of the back plate (one piece). That backplate/needle valve holder is NO GOOD. Why! well, when the backplate heats up, it tranfers the heat to the needle valve assembly causing the glow fuel to heat up and, the engine runs like crap and, always dead sticking and hard to tune. OS figured it out and,the later models of the 91FX have the same needle valve holder as the one on the OS 61LA series. If anyone has the older type of backplate, I highly reccomend changing to the OS 61LA set up. They have a kit which inludes the back plate, with the chromed needele valve holder. You still use the same plastic needle valve.A lot of people thought that OS did that change for cost savings reasons but, that was not the case. I currently own 3 of them. Now I want the new 95AX...