anotherhobby

I have an Avistar with a 40LA that I would like to change. I came across a Magnum 52 4stroke and was wondering if anyone
else has tried this combo. Also, this plane tends to bounce on landing. Is it me, or the plane? Seems like the wire gear is
causing it, but I'm not positive. I thought about bracing the landing gear a bit with some similar sized material. Thanks for the help.

MinnFlyer

My Feedback: (4)

Bouncing on landing can be caused by several things. Unfortunately it's usually caused by a bad landing.

But you could try moving the CG back in 1/8" increments. This will make the plane slow down more easily on landing, but it will also make the plane more sensitive to the elevator. Move it back too far and it will be uncontrolable - that's why you want to move it back in small amounts

Sneasle

The LA .40 is enough engine for the plane. The .52 4S won't necessarily give you more power. Be careful though. I have a .46 2S on mine spinning an 11x5 and I am at a minimum of prop clearance. If the .52 wants a 12" prop or larger, I would not use it.

Edit: That .46 will almost hover the plane... almost..

anotherhobby

Putting the 52 4S in the avistar is not intended to add more power (46ax) but really a preference in sound and a slightly extended flight time. I am more concerned with a slight power loss. Am I correct in thinking it will climb better with a 4S but lose a little speed?

bigedmustafa

My Feedback: (2)

The flight characteristics can be maintained if you prop the engine similarly to your .40 LA. This could be a challenge, however, as the recommended break-in prop for the RFS .52 is 12x5, and this could cause ground clearance issues for you.

This engine is slightly heavier than the .40 LA also, but only by a couple of ounces.

Have you considered that you might improve the sound quality and flight times of your Avistar by switching to a ball-bearing .36 engine? This could also lead to an improvement in power if choose a Thunder Tiger Pro .36, for example.

Mr67Stang

You will pick up torque with the .52 four stroke and be able to use an 11 inch prop max. I think, as you suspect, the plane will have more initial pull but lose top end speed... but trainers don't need speed. I would go for it maybe with an 11x4 or 11x5 prop unless you want to keep some of your speed go with a 10x6. The other gain you get with this engine is a really cool sound

Insanemoondoggie

I instaled a Magnum 52 4c in my LT40 a few weeks ago. It is converted to a taildragger so the 12x6 prop clearance is not a problem.

I`ve had 3 engines on this trainer. ST GS40 , Evo .46 and the 52 Magnum 4c . The 4 stroke did slow it down , maybe a tad , but I no longer have to do maneuvers at WOT.

The Evo .46 is a power house, turned a 11x6 13.000 rpm`s plus . It was just to much for this type of airframe ,

The SuperTigre GS40 is a sweet little engine , and was a really good fit for this plane. And was an ideal setup when I first started to teach myself to fly.

The Magnum 52 4c has the torque to pull the plane thru Cuban 8`s , Hammerheads , loops, etc. It sips fuel, even WOT and doesnt slime the plane so bad. Only problem I`ve had , is the LS needle turning on it`s own in flight. I silicone it in place and have`nt had a problem since.
The first gallon of fuel thru the Magnum, the power was lacking but once she started to get broke in , the power just keeps getting better. When I switched over to the 4 stroke, I got several comments about how the plane seemed smoother in the air. It does seem to fly better . The little engine has a sweet sound and once set and broke in, has preformed flawlessly.

Jim_Purcha

My Feedback: (8)

I flew a avistar last year with a super tigre GS40, no problems pulling the plane around.

TimC

I'm running an O.S. .52 four stroke in my Avistar. It's a good combination. I don't remember what prop I'm using but there is no problem with ground clearance. The .52 provides plenty of power for the intended use of the Avistar.

anotherhobby

Thanks for the help. Looking forward to swapping it out now. Just need to break it in on a test stand some more. 2 tanks down so far.

Mr67Stang

You have two tanks through it... Go out and finish breaking it in in the air. Get some stick time from that fuel.

bigedmustafa

My Feedback: (2)

The RFS stands for Ringed Four Stroke. Magnum is pretty specific about their break-in instructions for this motor, they recommend a series of short (two to three minutes) runs at full throttle followed by cool down periods until you have half an hour of run-in on the motor before you fly it. You very, very gradually start to lean the high end needle toward just-rich-of-peak throttle during these short runs.

anotherhobby will have more long term success by continuing to follow Magnum's break-in instructions.

TideFlyer

Minnflyers right about most bounce in landings being caused by not-so-great landings. There is a phenomena, however, known as the " Avistar bounce ". Leads one to believe that the plane is somehow a bit more susceptible to bouncing unless you hit the landing perfect. One thing I did with mine that helped my landings was to put a nose wheel on the front gear that was a little smaller than the mains. That will impact prop ground clearance, but slants the wing downward just slightly. Helps hold the plane on the ground on landing, at least for me.

Chondar

I fly an Avistar with an OS 40LA as well. Maybe 30-40% of my landings are bouncy, but I figured that's just the pilot.

A guy at the field last week saw me bounce one of my landings and said he had swapped the stock landing gear on his Avistar for some aftermarket gear and had good results. Does anyone know what gear he might be talking about?

Insanemoondoggie

I`ve used this gear on an LT-40 and have seen it on an Avistar [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXNM65&P=0]Dubro.[/link] Worked much better than stock landing gear . When I first started flying , I bet I knocked it off a couple dozen times and had my share of bounce`s . It is tough.
My landing improved after a couple 100 touich-goes and a case of fuel. Very rarely bouce now , and gear stays on now. lol

TimC

anotherhobby, I just checked which prop I'm using with my .52/Avistar. It's a wood 11x7Wide. The wheels are 2ΒΌ" diameter.

Chondar

Thanks for the tip, insanemoondoggie. I'll check those out!


-Jay

Bax

My Feedback: (11)

Most "bounces" on tricycle-gear airplanes are caused by landing with the nosewheel hitting the runway slightly before the mains. The drives the nose up, and the plane goes up, too. If you land main wheels first, the nose will lower, and the model will "stick". Too many modelers land too fast, which causes the nosewheel to touch first. This is noticed on hard-surfaced runways. On grass, you'll likely not see the bounce unless you are landing 'way too fast.

Very likely, you're doing the same thing. Take the model up high and see how slowly you can fly it before it stalls. Find out which elevator trim setting will give you a nice, slow glide, but still very controllable. This is your landing approach speed. It also allows you to adjust the glideslope with throttle instead of using the elevator to control the slope. Then, when you near the threshold of the runway, just cut the throttle, and ease the aircraft into a nose-high position. You should be able to touch down with the nosegear off the pavement. With some practice, you can actually hold the nose off the pavement for quite a while before the model's slowed enough that it just drops. On grass, the nose will come down instantly, due to the braking effect of the grass.

Chondar

Yup, I use a paved runway. I've been trying to stay off the elevator on approaches and use throttle instead as you suggest but I've not got it down perfectly just yet. Time for more practice!


Jay

rambler53

My Feedback: (494)

You can use fuel tubing between the wheel collars and the wheel to give it some braking on the wheels, and you shouldn't land as fast as you may, which causes bounces too. I never wasted a 4 stroke engine on a trainer. Trainers are bash and smash items usually, and 4 strokes are twice the money as disposable bushing engines like the LAme.

-pkh-

My Feedback: (2)

I had an OS .50 SX on my Avistar... it flew very nicely. I only put a .40 LA on .25 sized planes... power output and weight of a .40 LA is right in between an OS .25 FX and a .32 SX. I had a .32 SX and a .40 LA in a .25 sized SPAD awhile back, the .32 definitely had more power, but the .40 wasn't too far behind, and it was less than half the price!