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avistar mods

Old 07-22-2011, 08:25 AM
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skysail
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Default avistar mods

Hey everybody,

I built an avistar this summer with an OS 46. I learned how to fly it pretty well and startedto do aerobaticswith it. Can anyone recommend any ideas or modifications to help my plane fly better for 3d beforeI invest in another plane.Im also wondering what the best size prop would be for this engine.

thanks
Old 07-22-2011, 08:55 AM
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hugger-4641
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Default RE: avistar mods



Congrats on choosing the Avistar, it is a great trainer and actually a pretty good sport plane. But I'm afraid it is not a good choice for 3D. Itis a very sturdy airframe compared to planes designed for 3D.You could put a much larger engine and force it to do some things, but I would really reccomend looking at some planes that are designed for 3D. For sport flying, the 11X6 Apc is the best prop I've found for that plane and engine. For 3D you might try a 12x4 but I don't thinkyou're going to get the3Dperformance you are looking for with that engine.

Old 07-22-2011, 09:54 AM
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Default RE: avistar mods

I second Jerry's opinion.

Long time ago, somebody gave me a .40 trainer with a .60 engine, which he claimed was good for 3D.

I ended up crashing the poor thing, which was never a good 3D machine.

Good 3D planes are light and have huge control surfaces and a combination of engine (or electric motor)-propeller able to produce plenty of thrust.

You could spice up the Avistar a little to increase its capabilities as a good flier.

Welcome to RCU!
Old 07-22-2011, 09:58 AM
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skysail
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Default RE: avistar mods



Ok, maybe I shouldnt say 3d, but I want to be able to do rolls faster, do loops, fly upside down, spins, andthings like that.I want to bring out the "Sport" side of it. Also, what would be a good second plane that has potential for 3d flying that is similar size to my avistar.

Old 07-22-2011, 10:00 AM
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Default RE: avistar mods

Try this:

http://www.modelaircraft.org/insider/07_09/Fun-Fly.htm

http://www3.towerhobbies.com/cgi-bin...?&P=9&I=LXEDP0

http://www3.towerhobbies.com/cgi-bin...&I=LXDUL8&P=RF
Old 07-22-2011, 02:13 PM
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delman
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Default RE: avistar mods

Just increase the travel on your ailerons and elevator and move the c.g. aft a little to do the aerobatics you mentioned.
Old 07-22-2011, 03:29 PM
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Default RE: avistar mods

i put a bigger rudder with pull pull(external servo), larger ailerons, a much larger elevator, and built the wing with no dihedral.... i had an os55 with a 12x4 apc and it was decent,,, i didnt 3d too much back then.... if i only had it now ... it did pretty good snaps and a decent upright flat spin
Old 07-22-2011, 08:15 PM
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Default RE: avistar mods

ORIGINAL: skysail

Hey everybody,

I built an avistar this summer with an OS 46. I learned how to fly it pretty well and started to do aerobatics with it. Can anyone recommend any ideas or modifications to help my plane fly better for 3d before I invest in another plane. Im also wondering what the best size prop would be for this engine.

thanks
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Old 07-23-2011, 08:25 AM
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Default RE: avistar mods

Holy Anhedral Batman!

I currently have my Avistar uncovered for bigger ailerons with dual servos and am going to set up the center wing servo for flaps using the stock aileron linkages.
Also am going to flatten the wing and clip the tips square. Considering 1-2 degrees Anhedral also.

I really like the 12x4 APC my .46FX and a taildragger conversion makes it a little sportier too.
Old 07-23-2011, 12:40 PM
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SeamusG
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Default RE: avistar mods

I like where 1320's going with the Avistar. The wing rib semi-symertrical rib profile provides for decent aerobatic patterns. Reduce or eliminate the dihedral. Tail dragger? Only if you like a tail dragger (I do). Think about eliminating the rubber band approach or make sure that you have plenty in use to eliminate any possibility of the wing separating from or slapping the fuse. Cut the wing cheeks off so that you have better access to the engine & mount. With a bigger engine - reinforce or double the firewall. An Evolution 52 or OS 55 AX will give it plenty of scoot. Or a Saito 82 if you like 4-strokes (have one on my Hanger 9 ShowTime 50 which is a 3D-capable plane).

The pics show a bulky (guessing it was builder's 1st time) tail wheel, a 2nd rudder servo control rod for the tail wheel, the main landing gear support. It has an Evo 52 NXmounted. Icloned the approach shown in the pics for mine with the addition of 1/4-20 nylon wing bolts.

It kept new trainees happy doing "aero"maneuvers more easily than the tradition flat-bottom rib profile of most high wing trainers.

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Old 07-23-2011, 01:58 PM
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dredhea
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Default RE: avistar mods

MetallicaJunkie recommending building a wing with little or no dihedral. If you're going to build a new wing anyways, I would like to add that you might want to consider shortening the wingspan by clipping the wing by one bay on each side. The plane won't have as much lift, but it doesn't really need it if you want it to be sportier. The shorter wing will improve the roll rate.
Old 07-23-2011, 03:35 PM
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SeamusG
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Default RE: avistar mods

Don't think that you need to build a new wing. Pretty sure that the wing can be split at the root. A couple of (or one) new root shim can be made to eliminate some or all of the dihedral. Use a chunk of decent balsa block and sand it to the outline of the original root ribs. You might consider cutting the covering back away from the split so that you can run a 1" strip of fiberglass over the finished seam. Some use thin CA to lay down glass and others will use either Finishing Resin or 30-min epoxy diluted with alcohol (epoxy only - resin is thin enough). Don't go overboard with resin or epoxy 'cause it's a real B to sand. Fill the weave with filler. Recover making sure that ya got 1/4" overlap.

As far as clipping a rib "bay", covering is cheap - use a hot iron and seal the existing covering to the "new" tip rib and then run a sharp razor (aka - new blade) down the outside of the same tip rib. That will leave a flat wing tip. Cover it asis or fab up something you prefer. If you think that it's too soft lay down a new tip rib using 1/8" balsa and sand to shape. Then cover it overlapping the existing (sealed edge) covering making sure that you have 1/4" of overlap.

Hey - it's all practice ... 'cause we never get it just right.
Old 07-23-2011, 04:28 PM
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Default RE: avistar mods

I wouldn't go to all that much trouble modding it. CG at the aft recommended range and hotter control throws will make the plane capable of the basic aerobatics that the OP wants. Then when he moves to a purpose built sport or aerobatic plane, the Avistar will still be valuable as a trainer to someone new.
Old 07-24-2011, 10:39 AM
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Default RE: avistar mods

I watched a pattern pilot fly one of my trainers and was surprised at what it can do with a good pilot on the sticks. I'd keep the Avistar airframe intact. Delman's suggestions (post 6) are all I would do to it.

If you can spend $100 for a new airframe, the Wings Maker 'Wingman II' http://ecsvr.com/wgm/ShopDisplayproducts.asp?Search=Yes will do all of those maneuvers very well. It's not 3D but it excels at basic aerobatics.

Move the engine and electronics over from the trainer. If you crash while learning new things, you can move them back and be flying again very soon.


Exactly which OS46 do you have, and what prop are you currently using? My brother liked a 11x5 on his TT46Pro. He tried a 12.25x3.75 and didn't like it even though a lot of people do.
Old 07-24-2011, 12:54 PM
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Default RE: avistar mods

I'll second leaving the Avistar alone. It's a good flying plane as it is. Yes, for more advanced flying it can be improved upon, but it'll take you a long way. Start working on precision in your aerobatic maneuvers and master the basics of aerobatics, flying a consistent line, circles the same size, loops the same size, all with the same start/exit point right in front of you. High roll rates are one thing, being able to stuff like a slow roll across the field taking 10 seconds to complete requires a lot more skill.

If you want to 3D, then get a plane designed for 3D rather than force a plane designed to fly on the wing into something it's not designed to do.

Get a Twist 40 - everything you have will transfer into one, it will 3D and they are good flyers. I've got a Twist 60 and have a lot of fun with it.

Hogflyer
Old 07-25-2011, 07:24 AM
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skysail
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Default RE: avistar mods

Twist 40! Thats the plane I want, you think its a good second plane though?
Old 07-25-2011, 08:18 AM
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Default RE: avistar mods

Twist 40 is a great plane. So is the Pulse XT 40 if you can find one. You might also look at the U-can-do 3D. If you can handle the Avistar like you say you can, then you can probably handle any of these three mentioned. It would stillbe a good idea to have an instructor help you with the maiden, andusing a buddy box for the first couple flights would be good insurance to make sure you are ready.
Old 07-25-2011, 08:36 AM
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skysail
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Default RE: avistar mods



I am going to keep my plane original so i can teach my dad how to fly it. I will buy a new one and build it probably over the winter.
Also, I had a problem with my ailerons and servo. The servo turned one way more than the other. I centered it, tried to adjust it and nothing worked. All my servos are high tech, but I replaced the aileron servo with a futaba. It fixed the problem and it seems that the futaba is more smooth and responsive. What servo do you guys recommend?

Old 07-25-2011, 03:58 PM
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Default RE: avistar mods

You will hear a lot of different answers to that question. A lot depends on the application and what radio you are using. Hightech and JR are fine servos, and there arelots of cheaper servos to be found. I've stuck with Futaba to make it easier on myself to swap parts from plane to plane. For most of my .40 and .60 sized sport planes, I've stuck with Futaba 3004's forcontrol surfaceslike ailerons and elevators that see the most input fromme and my style of flying. These have ball bearings and give a smoother and longer lasting operation with less current draw from your flight battery than a non-ball bearing servo. 3004's are suitable for use in any applicationon a .40 sized plane, but I use 3001's or 3003's for the throttleand rudderas these servos don't typicaly see as much activation and they are a little cheaper than 3004's.All of these I've mentioned are standard servos and are not the cheapest you can buy, but are among the cheaper servos. Depending onwhere you buythem, they are$10 to$20 new. I've purchasedmanyhere on RCU and E-bay at much cheaper prices andI've found them to be very reliable and easy to repair.

Ona3D or pattern plane in the hands of a skilled pilot, a precisionservo or one with higher torque and faster responseis often a better choice due to the larger control surfaces and the faster response needed.When you pick the plane you are definitely going to build, you should check for threads on that particular planeand/or ask more questions here for betterrecommendations.
Old 07-26-2011, 08:45 AM
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skysail
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Default RE: avistar mods

hogflyer,
I think im about to order the twist 60, what are good servos for that plane, and what engine do you use?
Old 10-04-2011, 09:59 AM
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KEITH DOUGHTY
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Default RE: avistar mods

I HAVE A AVISTAR WITH THUNDER TIGER 54 4 STROKE AND 11X7 MAS PROP, IT HAS UNLIMITED VERTICLE AND WILL HOVER ALL DAY, BUT I DON'T KNOW ABOUT 3D. IT WILL ALSO TAKE OFF USING 8 ft OR LESS OF RUNWAY.
Old 10-16-2011, 07:14 PM
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Default RE: avistar mods

Finally finished my mods. After dragging A__ on this project I blew it out last week before going back to work this week.

I did end up uncovering the wing completely and separated the halves with a hack saw blade.
The metal brace was bent in the center to negate the dihedral built into the wing tube.
New joiner made out of 1/4" 5-ply.
The flaps work perfect and I simply bent one of the stock linkages 90 degrees to touch the other one and soldered them together.
Robart hinge points were used for all hinges.

Aileron and flaps both had the hinge gaps sealed with covering.
The plane flys beautifully! It is very precise in its movements and holds lines without wondering off.

Reminds me of my pattern ship.






Old 11-12-2011, 01:18 PM
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Default RE: avistar mods



Old 02-18-2012, 03:55 PM
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Default RE: avistar mods

Do you have any update pictures of your wing? 1320Fastback, your mod on your Avistar is the reason I joined up. I am doing pretty much the same mod, I had a spare wing, so I am keeping one original and making one into a flat wing with dual servos.
Old 02-22-2012, 02:14 PM
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Default RE: avistar mods

Nice looking mod to your Avistar.

Take your plane up, fly straight & level and slowly add in some rudder. The plane will roll in the direction of the rudder. This is due to the high wing location on the fuselage.

What you need is 3 degrees of anhedral on both sides to compensate from the wing location. I've done several planes this way and it'll let you fly knife edge and point rolls without aileron correction. Works great on Sticks.

A trick to cure the roll without cutting the wing apart is to add downward only end plates. You can make the plate from lite ply. Cut it even with the top of the airfoil, but extend 3/4"-1" below the airfoil. Hold it to the tip with a couple of servo screws.
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