Ava question???

[SaltyOne]

I built my new Ava over the winter. I followed the directions on the KC website. It said to put the back of the towhook 18" from the front of the nose cone. This is what I did. I notice when I balance the plane at 100 mm, the suggested starting point, the towhook looks to be about 1/4 inch behind the cg. I'm afraid to maiden it on the winch with the hook so far back. It could stall and be squirrley. I would like some feedback from an Ava owner as to where they have their towhook. Maybe the setting is ok at 18". I don't know, but I am a little suspicious. I notice the KC website also says the cg should be at 400 mm behind the LE. This would be about 1/2 way between the TE and horizontal stab. :eek: Any help is appreciated. Thanks.

George

[R. Carver]

Start with the CG at 33% of the chord. Move it back gradually until it gets too unstable for you to fly comfortably.
Set the towhook 1/8" ahead of the CG. Move it back gradually until it gets too unstable on launch.
Note that this works for all sailplanes :)

[neonbutterfly]

geroge..this helped me setting up my super ava....

http://www.rcsoaring.com/docs/AVA_Instructions.pdf



bob

[IBWALT]

Presently my tow hook is 18 and 3/16 inches aft of the tip of the nose cone and my c/g is set at 95 mm aft of the leading edge. It rotates nicely on launch and tracks very well. It's very stable during launch. I feel that 100 mm is to far aft of a c/g and makes the AVA unstable in the pitch mode. If the nose gets down it will stay down and as the speed increases it will pitch down even further and eventually want to tuck.

Walt

[SaltyOne]

Thanks Walt, Bob, and Carver for the help. It sounds like 18" for the towhook should be about right. I'll move the cg up to 95 mm and give her a shot. Now I just need the weather to cooperate. I was going to fly the Ava today, but it was too windy. Maybe next weekend. Thanks again.

George

[vintagesailplnr]

Thanks Bob:

The set up is great. About what I did for first flight.

They do not want to come down.

Why only 22 mm for spoilers - on most woodys - we have full 90 degrees for stop and go.

22 mm for full open?
TIA
Jim



geroge..this helped me setting up my super ava....

http://www.rcsoaring.com/docs/AVA_Instructions.pdf



bob

[IBWALT]

Why only 22 mm for spoilers - on most woodys - we have full 90 degrees for stop and go. 22 mm for full open? TIA

The monoboard spoiler on the AVA is a mixed blessing. Yes you can descend vertically from alt when the board is fully deployed and yes it will stop you on a dime. But all that performance comes at a price. When the board is deployed much past 22mm the horiz stab is partially blocked and there is considerable buffeting of the horiz stab. This is really no big deal unless you are trying to fly in competitions then the effectiveness of the stab is dependent on two things. How much speed your carrying and how much spoiler you have deployed. In other words the effectiveness of the stab becomes speed dependent. This adds another variable into the spot landing equation. One that cannot be solved with just a simple elev mix. Because the effectiveness of the elev depends on how much spoiler is deployed and how much speed your carrying. If you look at the AVAs that are being flown competitively you will find a lot with split spoilers. This allows an even flow of air over the horiz stab.

Walt

[vintagesailplnr]

Walt:
Thanks - I did not know that 22 mm was the optimum for not blanketing the elevator.

Split spoliers - two short blades outboard of the stab? Using provided monoboard.

OR, do you cut in new spoilers farther out UGGGGGHHHHHH?

I also have a flapped center section I have not used yet - flaps better than spoiler?

TIA
Jim



The monoboard spoiler on the AVA is a mixed blessing. Yes you can descend vertically from alt when the board is fully deployed and yes it will stop you on a dime. But all that performance comes at a price. When the board is deployed much past 22mm the horiz stab is partially blocked and there is considerable buffeting of the horiz stab. This is really no big deal unless you are trying to fly in competitions then the effectiveness of the stab is dependent on two things. How much speed your carrying and how much spoiler you have deployed. In other words the effectiveness of the stab becomes speed dependent. This adds another variable into the spot landing equation. One that cannot be solved with just a simple elev mix. Because the effectiveness of the elev depends on how much spoiler is deployed and how much speed your carrying. If you look at the AVAs that are being flown competitively you will find a lot wi
Ok,.th split spoilers. This allows an even flow of air over the horiz stab.

Walt

[IBWALT]

Walt:
Thanks - I did not know that 22 mm was the optimum for not blanketing the elevator.

Split spoliers - two short blades outboard of the stab? Using provided monoboard.

OR, do you cut in new spoilers farther out UGGGGGHHHHHH?

I also have a flapped center section I have not used yet - flaps better than spoiler?

TIA
Jim

Jim,

I have a Super AVA and a Std. AVA center section that I interchange on a Super AVA pod and Boom. The only difference between the Super AVA and the Std AVA fuse is the size of the rudder. I swap center sections depending on conditions (light air I like the SA and in windy conditions I prefer the Std AVA). On the Super AVA center section I cut the monoboard spoiler at the outboard ends and made two separate spoilers each 7 bays wide. On the Std. AVA center section I cut the monoboard at the outboard ends and made two spoilers that are 6 bays wide. The center of the monoboard is then taped shut. I don't get the terrific braking that I did with the monoboard but the vertical decent is much easier to control.

I also have an AVA-E that has a flapped center section and while it is fun to fly I don't feel that flap is as effective as the spoiler. Besides they won't let you use the flapped center section in an RES contest.

[vintagesailplnr]

Walt:
I have all three AVA's. I like the mini best of all.
Yes I know about RES, but I plan on learning (practice) to fly AVA's and use them in the local ESL contests. Maybe some day we will have REF as well!

I have a Supra as well, but not RTF.

The standard AVA was the last one I bought - so I am still learning.

We can now change planes during a contest - so Super AVA fuse, tail feathers and switch wing tips for late early afternoon when the wind picks up.

I'll look at the spoiler tonight and determine if I wish to do surgery on the wing, extra spoiler servo, wires, etc.

Thanks again for advice.
Jim

Jim,

I have a Super AVA and a Std. AVA center section that I interchange on a Super AVA pod and Boom. The only difference between the Super AVA and the Std AVA fuse is the size of the rudder. I swap center sections depending on conditions (light air I like the SA and in windy conditions I prefer the Std AVA). On the Super AVA center section I cut the monoboard spoiler at the outboard ends and made two separate spoilers each 7 bays wide. On the Std. AVA center section I cut the monoboard at the outboard ends and made two spoilers that are 6 bays wide. The center of the monoboard is then taped shut. I don't get the terrific braking that I did with the monoboard but the vertical decent is much easier to control.

I also have an AVA-E that has a flapped center section and while it is fun to fly I don't feel that flap is as effective as the spoiler. Besides they won't let you use the flapped center section in an RES contest.

[jaizon]

I also have an AVA-E that has a flapped center section and while it is fun to fly I don't feel that flap is as effective as the spoiler. Besides they won't let you use the flapped center section in an RES contest.

Walt,

What setup do you have in the AVA-e? BTW, my Xplorer flies. :D Thanks.

Preston

[IBWALT]

Walt,

What setup do you have in the AVA-e? BTW, my Xplorer flies. :D Thanks.

Preston

Preston, I have a Hacker B40 LMR (the one with the carbon case), aeronaut CAM carbon 16 x 10 prop, RF spinner and a PHX 80 esc. For battery power I am currently using a TP 2S 3300 mah 7.4 volt pack (keeps me in the 7 cell category in most LMR contests). Eagle tree says that it pulls almost 80amps on startup and then quickly falls back to the mid 60's in flight. Vertical speed is 2200 fpm and it gets hard to see in about 15 sec.

Walt

[jaizon]

Thanks, Walt.

I'm thinking of using the Neu 1506 2D 6.7 w/TP 2100 3s/or TP2200 ExtremeV2 CC 80. Too much, too little? What do you think?

[seanpcola]

Not trying to steal a thread, and I'll move it if you guys object, but question for Walt.

I have almost the exact same Avas as you. Really hot Neu setup on the EP. Super Ava has the mono spoiler, EP is flapped. I also have NIP Standard AVA V stab and rudder and also an EP Super Ava V set. I'm considering making the Super AVA EP and keeping the standard, flapped wing powerless. I don't fly contests so all this is strictly sport flying. Thoughts?

Sean

[SaltyOne]

Walt - I maidened my Ava last Saturday. It really flies great. Second launch off a highstart in light lift conditions I specked her out. Seems to go up on the proverbial ant's fart. The tow hook at 18" seemed just about right too. I need to get the spoiler/elevator mix optimized. I know what you mean about full spoiler being too much. She tucked under coming down from altitude with full spoiler, may have done an outside loop. My underwear needed a cycle through the washing machine after that flight.

The only problem I ran into on about the fifth flight, I was about to launch, and noticed the elevator flapping around. I detached the highstart and tried to tighten the elevator retaining screw. It wouldn't tighten. The threads were stripped. I took her home and drilled out the cf boss under the cf elevator mount where the retaining screw screwed in. I then epoxied in a ss M3 nut with a self locking insert where the boss had been. Now I can tighten the retaining screw to my heart's content without stripping anything. The locking insert keeps it nice and tight. Just hope I don't lose the retaining screw in the grass. I'd probably need to order a replacement from Barry. Thanks again for your help.

George

[Andy W]

Preston,
my AVA-E has the same B40, but I run Neu 5000mAh 2s LiPo's and a 17x13 prop. 100A for the entire (45s) climb gives me about 50% more fpm than Walt - about 2500' in 45s. before I used the Neu cells, I used 7x2200 NiMH - they couldn't handle 100A, so I had the same 16x10 for about the same climb rate as Walt.
..a

[IBWALT]

Not trying to steal a thread, and I'll move it if you guys object, but question for Walt.

I have almost the exact same Avas as you. Really hot Neu setup on the EP. Super Ava has the mono spoiler, EP is flapped. I also have NIP Standard AVA V stab and rudder and also an EP Super Ava V set. I'm considering making the Super AVA EP and keeping the standard, flapped wing powerless. I don't fly contests so all this is strictly sport flying. Thoughts?

Sean

Sean, I think that you can pretty much do what you want with the AVA. I use the SA center section when the lift is lighter and the reg. AVA center section for higher winds and when the lift is greater than light. I don't change out the vert. stab I just use the SA vert. for everything. The horiz. stab on the SA and the reg AVA are the same size. I also have not tried the SA center section on the AVA-e fuse. I am sure that it would work but the yaw response would be a bit slower due to the smaller rudder on the reg AVA and the AVA-e. One thing that I do though is set up a dual rate on the rudder and reduce the throw to about half of what I use for thermaling. This reduces the amount of Dutch roll that you can get when you use a bit to much rudder and really helps around the landing zone.

The only problem I ran into on about the fifth flight, I was about to launch, and noticed the elevator flapping around. I detached the highstart and tried to tighten the elevator retaining screw. It wouldn't tighten. The threads were stripped. I took her home and drilled out the cf boss under the cf elevator mount where the retaining screw screwed in. I then epoxied in a ss M3 nut with a self locking insert where the boss had been. Now I can tighten the retaining screw to my heart's content without stripping anything. The locking insert keeps it nice and tight. Just hope I don't lose the retaining screw in the grass. I'd probably need to order a replacement from Barry. Thanks again for your help.

George, This is a common problem with the AVA and the Supra. The fix that you did sounds like a good one. I just drilled a little deeper and tapped the hole and screwed in a longer stud. Then added some thin CA to stiffen up the upper part of the hole that the old stud pulled out of. I would not tighten the nut to hard though. The the mounting block in the horiz. stab is just a piece of balsa capped with some CF. If you tighten it to much it can crush the balsa. I used an exacto knife to poke some small holes in the balsa block and then took some thin CA and let it soak into the balsa around the hole. Now I don't worry about over tightening the screw.

Play with your c/g a bit and you might find that a little more forward than what is recommended is more to your liking. Also once you get the spoiler>elev mix setup you will find that you won't need to change your drawers as often.

Walt

[IBWALT]

Preston,
my AVA-E has the same B40, but I run Neu 5000mAh 2s LiPo's and a 17x13 prop. 100A for the entire (45s) climb gives me about 50% more fpm than Walt - about 2500' in 45s. before I used the Neu cells, I used 7x2200 NiMH - they couldn't handle 100A, so I had the same 16x10 for about the same climb rate as Walt.
..a

I asked Andy about his setup when I was putting my AVA-e together and would probably have gone with his hotter setup but a Castle PHX 80 was about all I could afford after buying the motor. :D There is also a caution on the box the B40 LMR comes in about 60 amps being the max. But after talking to Hacker and others that pull a lot more amps I feel that this 60 amp rating applies to people that have longer motor runs than we use for sailplane LMR competition.

Walt

[seanpcola]

Hi Walt,

Thanks for the reply. I have heard a lot of people interchange the two sections and I know the horizontal is the same. I have all of the combos sitting in the box and plan on setting up the Super AVA-E vertical with servos soon.

Guess I'll experiment around but guessing that with my style of flying I probably will settle on keeping the S-AVA as EP and the standard non-powered.

Sean

[jaizon]

Thanks, Walt. Hoping to have it in the air in about 10 days. :D

[Andy W]

One more point on power - I always design my power systems for competition, not that I compete very often, but when I do, I want to be competitive with whatever model I take..
If you are flying for fun, there is no need to stress components so much..
..a