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Author Topic: A-6  (Read 18207 times)
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Alan Mkitarian
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A-6
« on: January 31, 2009, 11:56:03 AM »

Wonder if anyone is flying this event? Look like a fun event with simple rules. 30 sq. in wing area, 6" prop with 1/32 blades flat, 6" motor stick, wood size 1/16 sq.,wing and stab ribs 1/32 thick x 1/16", min. weight 1.2gr. Can anything be simpler?
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Maxout
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« Reply #1 on: January 31, 2009, 12:39:49 PM »

Alan, I fly them. It's a challenge to make the minimum weight, and the prop limitation make it extremely difficult to make a good flaring prop without having the prop spar be too fragile. The flight times are pretty long. I've gotten to around 5 minutes in low Cat II sites, but that just isn't enough. They are fun airplanes, but if you want to be competitive, they're almost as fiddly as ministicks and EZB's. Be wary of the ones with high AR wings. They are real stinkers if you don't have world-class wood. The more normal ones are easier to deal with. Also note that there is no longer a limit on stabilizer area. I've seen this used to good effect. The single biggest challenge to A-6 is getting a ~14" loop of rubber to go onto a 6" motor stick without bunching against the stick. You need to use a long rear hook and long nose bearing to get the motor as far from the stick as practical (I usually go with ~3/8", with is extreme compared to model indoor models).
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Olbill
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« Reply #2 on: May 04, 2009, 04:25:49 PM »

I agree with part of what Maxout said. Like most duration models they have to be at the minimum weight and it takes 4# wood to get there. I also agree to avoid high aspect ratios for two reasons. Number one is the spars are too heavy. Number two is the incongruity of having a sub-2" wing chord behind a 1/16" deep spar. My model (USIC winner in 2007) uses a 14" wing span.

I also agree with the difficulty of getting the motor to unwind - but I'm flying 18" to 20" loops. A 14" loop would be a breeze!

I don't really agree that A-6's are hard to fly. I've only built 2 - both original designs - and both flew well. A lot of people in my club fly A-6's and all fly well. Just not very long. (remember the part about weight?)
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amcfarland
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« Reply #3 on: November 24, 2009, 07:18:02 PM »

I started my recent indoor activity with a couple of A-6's from Indoor Model Supply. The great thing is that the props are simple and you can build the things in an evening. I built two of the high aspect ratio models ("lew's A-6"?) which flew alright for a first try (1:37) in a cramped and cluttered marginal cat 2 space.

The high ar models came out much lighter (2.2g vs. 3.2) and flew much slower, but also seemed finickier (?) to trim.

The other issue was that I only had 1/16 rubber which came with the model and it was WAY to much for the space. A helpful flyer donated some .050 and it was much happier.

Though I'm currently working on a limited Pennyplane, I will continue to fly the A-6, especially if I can find some competition events in the area.
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Olbill
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« Reply #4 on: November 25, 2009, 12:39:26 AM »

For the weight of your A-6's 1/16" rubber would be fine. Like all low ceiling indoor models with fixed pitch props you need to wind to near maximum turns and then back off to the launch torque that will give you a safe flight. My last A-6 flight on 11/08 used a 14.5" loop that weighed .85g. This is probably around .050" but my model weighs 1.2g. Motor was wound to 2580 turns and .35 in-oz then backed off 520 turns to .1 in-oz. Flight time was 5:33 in our Cat 1 site.

If you want to get the weight down to 1.2g you need to find some 1/16" square wood that is 4.0 pcf or less for the wing and stab spars. The prop blades and the boom also need to be from really light wood. Don't worry if the boom seems flimsy - it will still work just fine. There is a difference in condenser paper weight. If you can find the really light variety that Lew used to sell that would also be helpful in keeping the weight down.

There's an A-6 cookup on SFA with a lot of build details on my A-6 on the last 2 pages.
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amcfarland
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« Reply #5 on: November 25, 2009, 01:03:05 PM »

Thanks for the feedback. Yeah, among other things I was using maybe 8" loops and hadn't heard about backing off yet. Live and learn. Should probably get a torque meter also. Off to the cookup...
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Olbill
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« Reply #6 on: March 02, 2010, 08:31:16 PM »

The A-6 pictured above set a new site record at the Pikes Peak Ceiling Climb last Sunday. It broke its old record of 5:39 with a new one of 5:59.
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Tmat
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« Reply #7 on: March 02, 2010, 10:20:33 PM »

Well done Bill! Cool

Tony
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F1B guy...
But don't hold that against me!
Olbill
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« Reply #8 on: April 10, 2010, 07:31:37 PM »

Another milestone for the BG A6 today. I shattered my local Cat 1 record of 5:34 a no-touch 6:12. This model just gets better and better.
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Olbill
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« Reply #9 on: February 28, 2011, 03:27:43 AM »

Add another win for the A6 at the 2011 Pikes Peak Ceiling Climb on Sunday, Feb 27.
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TimWescott
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« Reply #10 on: April 16, 2011, 03:18:38 PM »

There's an A-6 cookup on SFA with a lot of build details on my A-6 on the last 2 pages.

What is SFA?

 Embarrassed
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hastf1b
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« Reply #11 on: April 16, 2011, 04:18:49 PM »

Look at here: http://smallflyingarts.com/

Heinz
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Olbill
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« Reply #12 on: May 30, 2011, 05:24:06 PM »

The A-6 flew well at USIC but was suffering from being 80mg overweight. This is not acceptable against the best A-6 fliers in the country. Tom Sova won with 9:33, Tem Johnson was second at 9:21 and I was third with 9:11. I did have a new accomplishment at USIC in A-6 - on my first flight I hung my model on the ceiling after it did a tail stand climb all the way up.
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Olbill
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« Reply #13 on: December 06, 2011, 03:41:15 PM »

My A6 has been suffering from having a bad prop bearing and also being a little overweight. I've made a new bearing for it and will maybe build a new wing and tail soon. The prop bearing is made from a Harlan F1D bearing. The stock F1D bearing is much too long for an A6. With the 6" nose to rear hook limitation you don't want to lose any more space than necessary. The first picture shows a stock F1D bearing alongside the new modified one. The second picture shows where the modifications are to be made.

The hardest part to do is drilling a new hole for the prop shaft. I used a #80 drill for the hole to go with my .012" prop shaft. The rear pigtail on the Harlan bearing is made for a .013" wire so I pinched the pigtail a little to tighten up the fit.

The last picture shows the whole motorstick with the new bearing and a new, lighter rear hook. The weight of the motorstick and tailboom went down about 40mg with the new parts.
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Olbill
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« Reply #14 on: December 14, 2011, 11:44:05 AM »

To continue the diet plan for my A6 I decided some new flying surfaces were needed. I found some really light scraps of condenser paper that I bought several years ago from Don Slusarczyk. This paper weighs 3.6mg per square inch. Compared to my normal supply of CP which weighs 5.2mg per square inch this paper would save close to 100mg for the model. I covered an already built stab with this paper. The finished stab weighs 309mg.

For a new wing I cut about a lot of 1/16" square sticks from various pieces of balsa. I used to think that the lightest wood you could find would be okay for A6 spars but this didn't work out. Several pieces of low 3# wood wouldn't work at all. It would either curl when stripped or just fall apart. I finally got some wood in the low 4# range that produced promising spars. I cut about a dozen spars from 18" sheets and selected 2 pieces that weighed about 60mg each. Ribs were cut from 4# 1/32" IMS wood. A set of 5 ribs weighed 30mg. The final finished wing weighs 306mg.

My wings have been coming out at around 12 1/2" span instead of 13 1/4" that I need for 30 square inches. I added 1/2" to the center span and also left out the center dihedral break.

All these new parts gave me a model that was about 40mg underweight. I brought it up to weight by adding a stiff balsa doubler to the tail boom between the tail posts so that left side tail washin could be adjusted by twisting the boom. Without rubber the model now balances at about 1/4" behind the rear hook.

Here's a picture of the model with the new parts.
(NFFS Model of the Year btw)



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Olbill
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« Reply #15 on: December 29, 2011, 10:44:18 PM »

The A6 did well at Tustin today. On Tuesday Gary Hodson set a new Cat 4 A6 record of 9:43. Yesterday I arrived at the hangar at about 1:00 in the afternoon and spent the afternoon doing trim flights and looking for gremlins. Today at about 1:00 I finally broke thru problems with my prop flaring too much and posted a 9:51 for a new record. At about 3:30 I felt like the air had improved enough to try again with a lighter motor and managed a 10:20.

Gary will be flying tomorrow and Saturday so my record may not last long. I'm planning on flying LPP and F1L tomorrow unless Gary forces me into getting the A6 out again!
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ykleetx
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« Reply #16 on: December 29, 2011, 11:36:44 PM »

Kudos to Bill.  The 10:20 record flight was very nice.  It did not climb super high, only to about 110', but it has a long slow descent.  A very nice flight indeed.

But the "battle" isn't over.  I expect Gary Hodson to counter strongly tomorrow.  We're looking at another sunny day tomorrow with the high in the mid 70's.

-Kang
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Olbill
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« Reply #17 on: January 01, 2012, 03:22:53 AM »

The report from Tustin is that Gary Hodson didn't quite overtake my A6 time so my 10:20 flight will become the new Cat 4 record. Kang posted a video in the Tustin section that shows the first part of the record flight and a great flight by Gary. This was a fantastic several days of flying in one of the best indoor sites in the world.
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Randy Reynolds
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« Reply #18 on: January 01, 2012, 11:43:39 AM »

Congratulations Bill!  We look forward to seeing you in Colorado Springs for the Pikes Peak Ceiling Climb.  It will be held at the City Auditorium and the good news is that the ceiling has been repaired.
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NormF
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« Reply #19 on: January 01, 2012, 11:45:33 AM »

Congratulations, Bill!

Brian's pictures of the whole week at Tustin are at: http://www.flickr.com/photos/[email protected]/sets/72157628586372885/

- Norm
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« Reply #20 on: January 01, 2012, 12:27:26 PM »

Bill
 Great flying!!  10:20 with your A-6 is fantastic.  Kang's EZB flight was also very nice.
Keep up your great efforts.

Charlie Coeyman
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sweepettelee
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« Reply #21 on: January 01, 2012, 01:43:09 PM »

Now is the time to send my congratulations on your fine A6 record flying, Bill.
Indeed, it was a pleasure to be an observer and be the CD that signed the record application.

Mind you, Gary had a flight going on Saturday I would have bet was going to better yours...
when it came in inverted!
I believe the rubber decided to leave the hook at approx 10 minutes and maybe 30ft high! 
Shock & disbelief...
Those little puppies that you both flew so well are delightful.
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Leeper
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« Reply #22 on: January 01, 2012, 05:25:18 PM »

Thanks Lee. Yes there are a lot of little niggling problems that can happen with A6. The closer you get to 10 minutes the more likely it is that one of them will bite you. I've had all of them at one tome or another.
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ykleetx
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« Reply #23 on: January 01, 2012, 05:55:20 PM »


On Saturday, Gary made excellent attempts at the record, and one came tantalizingly close. Gary adjusted his prop and motor earlier in the day and was able to climb even more strongly than before. His flights topped out at about 140 to 145'.

On his best flight, the model flew beautifully, and it appeared that it was going to come very close to Bill's record. At about 20 to 25', the model ran out of turns. Even worse, the motor came off the prop hook and was hanging down from the back, and the model dropped straight down like a leaf. That flight landed at 9:59.

It was a really great battle to witness. All of us at the hangar enjoyed the competition tremendously. Congratulations to Bill and Gary for flying their A6's so well, and congratulations to Bill for the new A6 record.

The A6 battle is just starting for 2012. The Cat II record will be on the line at Kent in April. Attempting to break Bill's Cat II record will be Tom Sova, multi-time A6 winner at USIC. Tom tells me that he has just designed and built a new A6 especially for Kent. I can't wait to see it. We are hoping that the Kansas City crew of Gary, Emil, and Tem will make the trek to Kent.

The A6 drama will continue at USIC. Johnson City has produced 10+ minute A6 times. The best official A6 fight in history was made at Johnson City by Tom Sova in 2006. The flight was 10:21, :01 better than Bill's new record of 10:20.

Then, I hope the battle of the record holders continue at Lakehurst in July. Perhaps the 11 minute mark will be broken there. It might not be the height of the building that will matter, but rather the quality of the buoyant evening air. Bill's 10:20 was flown at no more than 110'.

-Kang
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ykleetx
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« Reply #24 on: January 03, 2012, 11:34:28 PM »

Here's another video of Gary Hodson's A6.  This one is from Saturday, after Gary had reduced the pitch of his prop to get a stronger climb.  His A6 climbed very strongly, and it reached a height of about 145 on each of his three flights on Saturday.

http://www.youtube.com/watch?v=z1Lp6jB5050
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