I.ve got an Avistar with an LA 40 but I have a brand new LA65 and was wondering if I could put this in my Avistar or is it too much motor?

It will be OK once you are confident at flying...

I know a guy who did a similar change with his trainer after he got his wings and it was like getting a new Airplane with the extra power etc...

Confidence and ability first though...

Matt

A 65 is a big step up over a 40 for a beginner. If you are a newbe then I would wait till you were a bit more experienced then I would give it a go.

Hi!
If your Avistar is around 150-170cm in span I would definitely say NO!
Just put a 11x5 or a 11x6 APC on your LA.40 engine and run 5%-10% nitro and you'll se that your LA.40 is perfect for your airplane.
Regards!
Jan K
Sweden

You will probably get all sorts of answers to that question, so I will add mine.

You can probably put whatever engine you want on whatever plane you wish (within reason.. for instance, I would not put a gas engine on a glow 40 trainer, it would not fit, for one thing.. but putting a 60 size on your trainer, well, I guess it would work. You would have to deal with the changing CG and spend some time getting the right prop for the job, but you can expect that you will have much faster approaches than you may be used to (because of the limitations on prop sizes and pitch vs length), and you probably would never really go to full throttle with it, possibility exists to rip the wings off in a dive for instance.. but if you can control it, and can get the CG at a reasonable point without having to add a pound of lead [:@] to the rear of the plane.. then... it's up to you.

If it were me, though, I would get to a point where I was really comfortable with this then move into a low wing 60 size like the Tiger 60 or the Four Star 60 and use the engine for what it was intended.

That's only my opinion.. and I have lots of them....

DS

It's your plane & you can do what you want to it, but I suggest that you don't do it.

The Avistar is a sweet-flying bird with a 40 & it is a tiger with a good BB 46 in it. However, 60-size motors are bulky & heavy for the modest extra output. Aside from the shoe-horn job to get it in, it will be grossly nose-heavy & you will have to add a lot of lead to the tail to make it balance -- thus really increasing the total weight. You should also beef up the wings to withstand the extra speed & aerodynamic loads, thus increasing the weight even more. It just won't fly the same anymore.

I'd put a ST G51 on that Avistar as soon as you've mastered it with the 40LA then when you're ready for a low wing trainer you can get a "World Models T-34 Mentor" and put the 51 in it, it flies VERY well with that engine

Joseph

I just soloed last Sunday (after 4 weekends of instruction with a buddy box) on my used and rebuilt Nexstar with a stock OS 46 fxi.

I just rebuilt a busted up AWARF Avistar (with the plastic tipped wings and tails) and replaced the OS40LA with an OS 46 FX and flew it today.

My instructor did the take off and landing but I took the controls for most of the flight.

As a beginner with about 2 gallons of fuel thru my blood, I can truly say that this plane is MUCH faster and MUCH more responsive to stick movement.

It was a blast to fly around the field in about half the time the Nexstar took --and that was at 1/2 throttle.

Now I finally know what pilots mean when they say it tracks like it"s "on rails".

My instructor flew it at full throttle and it seemed to do almost anything he wanted. He was really impressed--almost as much as me--with the way it handled.

I can't see anything more powerful than a 46 on this airplane especially because of the CG problems the added weight would cause.

I'm glad to say that I am a proud papa of a really nice 2nd plane. This should take my piloting skills thru at least the fall --and will have a permanent place in my hangar.

I don't think I have the confidence to land this plane as of yet ---as it comes in really fast compared to the Nexstar. At least today I didn't have the confidence -- I'm going out tomorrow and I might try it if my Nexstar's take offs and landings are confident.

If you aren't real comfortable landing at high speeds then keep the 40LA on it.

By the way, I moved the engine as far back as I could and moved the battery pack aft - behind the servo tray. The CG is right on at 3.25 inches behind the wing's leading edge. I used 14 rubber bands with the last 2 criss crossed.

Good Luck,
root

I recently resurrected an Avistar, converted it to a tail dragger and installed a K&B screamin' 48 which is plenty of engine. I usually fly at 1/2 throttle and it gets very slippery at full throttle. It is a very agile airplane with a few modifications to control throws. Remember that just because there is more than enough engine, you don't have to use all of it, sure helps when you get in a situation when you need it though.
-Tom

What size and brand prop are you using?

I just bought a 11x4 APC that I read from other threads will give me a slower speed, more vertical, shorter take offs and slower/shorter landings.

I have a 10x6 on it now and it's a rocket for my present newbie reflexes.

I'll also try out the trusted 11x6 that seems to be the standard. Maybe even a 11x5 which I couldn't find at the LHS today.

I'm not ashamed of being "humble" as far as my skills go--cause I HATE crashing and rebuilding even though it's part of the hobby/addiction.

An experienced flyewr friend just told me to put at least 4 or 5 gallons thru my Nexstar (I'm on gallon #3) before flying the Avistar as my main plane.

APIA---What kind of control throw mods are you talking ?

I will be replacing the stock control horns with beefier plastic ones and metal 256 clevises for a fail-safe - "not being cheap" to blame upon failure.

root

Hi Root
The prop that works the best on my airplane is a Zinger 11.5 x 7.5, the engine turns around 13.5K about 4 clicks rich. I have thrown around a dozen props at it from APC to MA and this prop it likes. After around 4 or 5 flights, I tried some basic aerobatics and no matter how hard I tried I could not get the thing to spin. I went home and installed the largest servo wheel (futaba) I could find in my junk box. This increased the rudder throw an additional 3/8 inch and now it spins just like a full scale airplane.
As you said don't be ashamed to be humble as this will keep your airplane in one piece longer. I started out with a PT-40 and flew it for a long time before I thought I was ready for an increase in performance with the Avistar. Just a note with the Avistar, it is a lot more responsive and twitchy than a trainer which is not a problem unless you get BOLD. I still take my trainer out every so often for a getting back to basics flying day. Good Luck with your Avistar and don't get into too big of a hurry.
-Tom

Friends,
I found an 11x4 and heard what this does for landing --

acts like a break--when slowing down for landing ??

what do you guys think of this size for that purpose?

what do you think it will command of the OS46 FX???

do you think my needle will have to be tweeked??

root

An 11-4 does not provide adequate load for a 46 FX at full throttle in level flight. It is OK going straight up, but you will need to stay off the throttle on the level.

britbrat,

So an 11x5 (according to the other thread's post) is a better overall choice -or- an 11x4 3 blade for full throttle and braking.

I believe ?? the Evolution .46 NT trainer ?? uses a 3 blade (not sure of the pitch) in conjunction with another sort of prop "damping" adapter for slowing the Hangar 9's alpha for training purposes.

They are hard to find --at least at my LHS's.

I guess with the 11x4, I should be only using full throttle for take off and going straight up.

While in level flight, I'll be flying at 1/2 throttle anyway because of my newbie skills.

I really want the "braking qualities" of the 11x4 3 blade so I'll be on the lookout for a few of those--3 blades are a little more expensive (I think) and harder to find

I thank you for you recommendation/ knowledge.

Where did you find out about this? Can you direct me to the source?

root

1) Yes -- that's OK if you can resist the urge to twist the tiger's tail on the level

2) you are welcome

3) 56 yrs of modelling, 50 yrs of flying full scale, 37 yrs of fluid dymamics engineering