Avistar questions
 

Just purchased a Hobbico Avistar and an OS 46LA. The engine mounting procedure concerns me a little. You're suppose to put the engine on the mount, and then secure it with the 2 mounting brackets/straps that go over the engine flange. The mounting brackets then get bolted to the mount. The engine is basically clamped in. With the supplied mount, the engine appears to have lots of side-to-side play prior to securing with the brackets/straps. Is there a better way, or is this normal mounting procedures that will adequately secure the engine. I'm afraid it will wiggle loose. The mount came pre-installed. I have not yet mounted the engine. Not that far along yet. Also, the Avistar box lists recommended engines, and the OS 46LA is one of them. It also advises a 10x6 prop for this engine but OS recommends a 11x6 or 11x7. Which one should I use.

RE: Avistar questions
 

I had the same mount and engine on my Hobbico trainer. It never came lose or let the engine move even when I crashed and totalled the plane, but it just never felt right either. Even though it worked perfectly I won't use a mount like that again. Just a mental thing with me I guess.

OS says 11x7 prop for breakin so I went with that one.

BTW, the wing joiner on that plane isn't strong enough and broke on mine on a hard landing. Repaired it with fiberglass. If I build anouther I'd glass it duing construction.

RE: Avistar questions
 

Hi,

In reply to your concern about the engine mounting ("The engine mounting procedure concerns me a little.... The engine is basically clamped in. "), I can tell you they work fine. My first student used one of those mounts, and I cautioned him against it. When he used it anyway, I cautioned him to constantly check the screws. When he put it in the second plane, with no problems, I asked him if it ever worked loose. (Not detectably, he sez.) On the third plane I shut up. Looks like they've got a winner.

I would still check them every few flights....

The 10 X 6 prop on that engine might be a little noisy, the 11X6 worked good (on another student's plane.) I cautioned him against the LA, said it wouldn't have any power, he'd be disappointed, etc. Turns out it has plenty of power, handles an 11X6 or 11X7 just fine. If you're a student, you'll find the 11X7 makes the plane a little fast. (did I say THAT????)

Good choices. Enjoy.
Dave Olson

RE: Avistar questions
 

Some people have success with the clamp on type engine mounts. After taking every precaution it still cost me an airplane. You can throw the clamps away and drill and tap the mount to fit your engine. If you don't have acces to the right sized tap, drill through and a nut and bolt will do just fine either with a split lock washer or a nylon locking nut.

RE: Avistar questions
 

I have had the Avistar since June of last year when I started. I have used the clamps on a OS46fx without any problems. Just make sure they are real tight. BTW: I have had many crashes, cartwheels, and a fun fly where I hit a fence twice, the limbo pole, and still the engine did not move. In all my other planes, the engine has been bolted in, but this one seems to be ok.

RE: Avistar questions
 

That style of engine mount has been around for quite a while, and I've never seen one fail due to the design itself. You should check the screws once in a while, and it wouldn't hurt to locktite them when you install the engine, but no matter how you mount the engine, it always comes down to screws that could vibrate loose.

On the prop, I'd say try an 11x5, it will give you better climb and a slower straight line speed. Though for most training it won't matter that much, you won't be spending much time at full power. However the extra climb of the 11x5 could be useful when aborting a landing approach.

RE: Avistar questions
 

I want to thank all of you for taking the time to answer my questions, and so quickly. Nice to have the support and experience out there to rely on.

RE: Avistar questions
 

Hi I'm flying my 2nd avistar. My first had your setup and the clamps worked just fine however get some machine screws and the ball tipped allen wreches and it will make it a lot easier to do maitenence. Also make sure to use lock tight on the bolts. I have flown with a few props (10x6, 10 7 amd 11x7.5 )and the 11x7.5 was the best. It flies real slooow but it also has plenty of power to get you out of trouble
I have the OS 46La and I can't say enough good things about it.It has planty of power, it's quite, very dependable and with very little messing around it has never failed me. It would take me longer to tell you how easy it starts then to actually start it. I'm flying a second avistar which has the plastic wing tips and it seems more agile than the first. THe first crashed because of pilot error when I was messing around trying to make turns using only rudder and throttle. It flipped over on its back from about 20 feet up and I instinctivly pulled back on the elevator and it went straight in. The fuselage was in tough shape but the wing survived so I decided to get a second. Over all I am happy with the plane and would recommend it but I have been told its more and intermediate trainer and now that I have some expirience under my belt, I tend to agree.Good luck with it

RE: Avistar questions
 

I have a Hobbico Superstar and have found that the metal that is used for those mounting straps is horribly soft and flexed/deformed with approximately 25lbs of torque. In addition, the eyelets for the bolts are not small enough and allow for too much play. I am in the process of replacing all the hardware up front (its all junk-too soft, besides the actuall mount). A little bit of flexability is desireable but using a softness of 1.5 (exaggerating) for an engine securing plate is just not sufficent in my mind.

Even if im just being over-cautious, at least I'll have peace of mind.