Doc Austin

So, what came first, the speed obsession, or the Aspera? Uhhhh, that's a little hard to tell. For awhile we have wanted to put together a super ballistic electric sport plane, but there were so many obstacles that it wasn't practical.

First and foremost, we aren't designing anything from scratch, because that isn't what we do. Our forte' is taking standard stuff off the shelf and getting all we can squeeze out of it. Most of the time this is just setup work followed by flying the crap out of it, but for this project, it appeared we were going to need more than just a big heart and lots of stupidity behind the sticks.

Our dilemma was further complicated by the need for our project to remain a sport plane. This means that the industry glut of unsuitable 3D airplanes was going to make the pickings pretty small. Doing something as overtly stupid (which we have been known to do) as jamming a 4s Power 10 on a Mini Funtana was just going to blow up some expensive stuff, so we had to dig deeper.

Of course, all this started out innocently enough when team members wanted to have the fastest Mini Ultra Stick in the group. Every Sunday always seemed to degenerate into a wild race around the two trees at the opposite ends of our field and it naturally got out of hand from there. Once we stepped up to 4s operation, the little Minis became stupidly fast...so fast, in fact, that we were on the very edge of controlling them. In the 40 year history of the stick, they have been exceptionally prone to fluttering, so it simply wasn't responsible to push it any harder considering what can happen when you blow the tail off a 100mph airplane.

The Ultra Stick 25E was a different story though. While the plane was a touch disappointing on 3S operation, on 4 cells and Power 32 motor, the plane was absolutely perfect, but it has so much drag that it will never be suitable for ballistic speeds. Having considerable stick time in 4S mode, we concluded the plane was fast enough and any more would spoil her great sport flying nature. Since I have a soft spot in my heart for this plane, I decided that enough was enough. The Mini and the 25E remain my go-to airplanes for general, effortless, no maintenance fun and stupid death-defying antics.

It was obvious that we were going to have to find something similar to an old AMA style pattern plane. These planes are made to fly smoothly and precisely at very high speeds. Most AMA style patterns planes groove exceptionally well and they tend to lock into that groove even better with more speed. In spite of being super fast planes that go, and stay, exactly where you point them, they are very easy to fly, so this is exactly what we needed. Unfortunately, that style of competition went away in the late 90s, and since there is little demand for those fire breathing majestic beasts, very few manufacturers have carried that kind of design into the electric world.

The closest thing we had seen to what we were after was the E Flite Brio, but it was already a brick with the standard power supply. Jamming in big batteries and a larger motor wasn't going to make it any easier to fly around because it was already a difficult plane. It was a nice plane, sure, but any heavier and it would probably be a handful, especially at low speed. There was no need to turn the thing into a slug just to get it to go fast in a straight line. We just want to go fast, and we might tear some stuff up in the process, but going this route would just be asking for it.

We were just going to have to scratch around until the right platform came around.



Or so, at the time of this writing, it would seem.

I instantly fell in love with the Aspera the moment I saw her. Everything looked just right, so right that I cut the check for the entire package. Since this was a different class of plane than I was flying, I needed servos, motor, new Lipos, ESC.....in short...everything. As if I cared. This was like dating a wild, sexy redhead who got you into horrible, unspeakable trouble and made you spend all your money on her. It was so much fun that you hardly noticed.........and definitely didn't care.

For those of you who may have missed it, here is my already considerable love affair with the standard Aspera:


From the very first flight, the Aspera was far and away the fastest electric plane at our field. It wasn't even funny how badly I was smoking off all the other nitro sport planes, so it never occurred to me to make it even faster still until Ben from 3D Hobby Shop made a harmless comment about making one ballistic.

Harmless, maybe, but it made sense because the plane is very slick. It is also supremely stable and forgiving, even when the throttle is pegged. So stable and inviting, in fact, I found it impossible to fly at anything but max velocity, Of course, check the video and you can see how well the airplane handles at slow speed. It's not necessary to fly the thing very fast, but it's so much fun that I can't help myself.

She's definitely a redhead.

I'm not afraid of her at all, and in fact, her high speed manners make me supremely confident with her, even right down on the deck. I'm sure we will one day have a very public and very nasty falling out like this, but she will definitely get the worst end of that deal. Good thing I've got another redhead stashed away in the closet, just in case.

Eventually the speed no longer impressed me, not because it wasn't fast enough, but because it was soooooo easy to blast by low to the ground and in close that it didn't scare me. Flying at these sustained speeds naturally took it's toll on run times, and the 4s 2070 pack was only delivering 6 to 8 mninutes. With the 3850 pack we were getting as much as 12-14 minutes. When I saw 3D Hobby Shop had 5s 3400 ballistic packs available at very resonable prices, I figured if I was going to carry around 3400+ mah of dead weight I may as well go for the extra cell and turn this into a moon shot.


Motor:
The standard power package for the Aspera is the Extreme Flight 2814 out runner motor. As noted in my review, this is a little jewel of a motor that loves to be thrashed.



For ballistic operation, we could go with a larger motor, or a hotter wind, but the purpose of this project is for pilots already flying and loving their Asperas to take it to the next level without having to replace all the gear. So, for now, we are staying with the 2814. If the Super Ballistic Aspera doesn't scare the bejeebus out of me in this configuration, we may well go to a hotter motor as the project progresses.

For now, though, the 5s 3400mah packs are already going to burn a $130 hole in your pocket, so we may as well use as much of the existing equipment as we have on hand....because it's already paid for. This means that the little 2814 faces torture instead of retirement.

Batteries:
3d Hobby shop has recently introduced it's own lineup of high quality 20C li-po packs. Generally they run about half what the major brands cost, so this is a welcome relief. As with everything else I've seen from 3D hobby Shop, I expect the batteries to be 100% top grade. While I was not in on the development program, my spies tell me that these packs performed well in the secluded, secret tests just outside of Fredericksburg, Texas.


These batteries are, however, shaped a little odd. They sort of look like a Klondike bar, so maybe there's a sponsorship opportunity there.



For our next project, we are planning on testing a Pulse XT with electric power. Since this plane will also use 5s power , we wanted a battery that would work in both planes, thus saving us a few dollars. The longer arrangerment of batteries won't fit in the Pulse access hatch, so we went with the brick style arrangement.


The only way they will fit in the plane is upright, and it takes a litte bit of thought to get them in there right. In retrospect, the long style of pack would work much better in the Aspera and not require any sort of modification at all. If we are pleased with the Aspera's performance (and not scared by it) on 5s power, we will probably acquire some 5s long packs for her.

Since this is such a big battery and it's sitting over a part of the battery tray that has big lightening slots in it, we wanted to beef that up. I laid a thin piece of hardwood sheet down over the tray and then put the velcro strip down over it. You'll notice I ran the sheet all the way forward on the tray, and this will give us the flexibility to go back to 4s operation if we need to. My club field is very tight and if the plane is too fast to fly there safely, I'll take her down to the huge Wimauma field to air her out, and run her on 4s at home.


The battery does seem a little odd looking sitting in there the way it does, but in this location the CG is right on the money. I am still not content that it is locked in there good enough, and I may glue a couple of popcycle sticks in front and in rear of the battery to keep it from sliding back and forth. The velcro holds it really well, but because of the shape the contact patch where the velcro strips meet isn't that large. You can't see it in the picture, but I set the velco retaining strap up so that there is a very big overlap. after the losing a battery out of my Aspera once (granted, out of my own carelessness) I want this thing really locked in there.


In my estimation, the 4s 3850 pack is pushing it as far as weight. The plane still has fabulous flight characteristics, but she is starting to become a little sluggish compared to flying with the little lightweight 4s 2070 mah packs. She is still very nice to fly though, but it takes more juice to push something heavy faster. We are stuck between staying light enough that the power system will overpower the weight, and having enough weight for the plane to penetrate at higher velocities.

As a good compromise measure, we have decided to go with the new 3D Hobby Shop 5s 20C 3400 packs. We will still get decent run times, the plane won't be too light, and it won't be too heavy. Maybe compromise wasn't the right word. Maybe it would have been a better choice to say "optimized."


Electronic Speed controller
We have switched over to the Airboss 80 ESC on our Aspera. Down the road we are planning a 5s Pulse XT conversion, so we will need an ESC for that. It also doesn't hurt anything that the ESC is so big that the batteries and motor will blow up first if we over stress the power package. Since the Airboss 80 is good for up to 5s operation, we will be saving the weight and complexity of a separate BEC, or even a separate on board radio battery. With the ESC running the show, the last thing we need at 100+ mph is for it to crap out and stop supplying power to the radio. I'm confident in this ESC. It has worked flawlessly in 4s application, and it's what we are going to go with.

I'm sure the Airboss 45 would be sufficient, but since we don't know how stupid we are going to push things, it made sense to begin with overkill on the ESC. Since 3D's technical guru is here so often, I will be content to take his word for it either way. He has never led any of us wrong and I'm sure he is watching this develop.



My Aspera was originally equipped with the trusty JR Sport 600 radio that came out of my Hangar 9 PTS P-51 Mustang. I liked the radio so much I held onto it when I traded the plane off and it's been a solid workhorse.

Meanwhile, I was testing out the new Futaba 2.4 F.A.S.T system in my Mini Ultra Sticks, and I gained enough confidence in those units to covert over to them 100%. The 2.4 is rock solid, and it even feels better than my other Futaba radios that are on 72. The antennae routing took some thought, but it ended up being a very tidy installation and I'm quite pleased with it. I just wish I hadn't poked that hole in the Aspera for the old style, mile long antennae.

Ben knew that I was going to fly the Aspera hard, so in the beginning he recommended that I use Hi Tech HS65s, with metal gears on the tail. Not being one to mix and match stuff, I chose to err on the side of having a powerful, rugged servo all the way around, and I'm running HS65MGs on all the control surfaces. With the potential speed increase, and corresponding mechanical stresses we are expecting with the ballistic setup, this became a righteous decision, especially since the grand total cost was only $20 more. If you are building an Aspera, you are spending enough money that it's better not to scrimp on the servos. I say buy the metal gear servos and be ready just in case you want to go ballistic later.

So, there is nothing trick in the radio setup at all. Looking at the speeds we hope to reach, it only made sense to go with well proven radio equipment and a solid airframe. Motors are cheap, and Ben's batteries are priced very reasonably, so those items are expendable when compared to my prized Aspera. I really don't care if I blow the motor or ESC up, or even if I puff up a battery, as long as the Aspera comes home safely. Of course, we are going to try to avoid those things, but we also know we are going to take it right to the edge, and that's when the unexpected can come up behind you and tear out a meaty chunk.


The Aspera is already a pretty stout airplane, but we are asking more from it that it was probably designed for. We were going to add a trick or two here to give the plane a little support under the stress we would be flying her through. Hey, we don't want her coming apart in the air, right?

Stabilizer Stiffeners
While the Aspera has a very rugged horizontal stabilizer, I was worried that the additional stress of higher speeds might be too much for it. At Ben's recommendation, we stiffened horizontal stabilizer with some carbon fiber struts. This modification is designed to strengthen the stab about halfway out, and the stabilizer won't be allowed to flex inward of that point and fatigue the wood where it meets the fuselage. In most high speed stabilizer departures, this is where the failure occurs. The carbon rods support the stabilizer so well that it is also less prone to bending (and thus steering the plane) when the surface is deflected at a high angle. This will show up most when you are pulling hard on the elevator and the airplane tracks perfectly straight.

This work was done by my master builder friend, Jimmy D. Jimmy drilled a couple of holes in the fuselage that were a little deeper than we needed. This allowed him to slide the carbon fiber rods in so he could line the other end of the rod up with the holes he drilled on an angle in the stab itself. Then, he just slid the rods out until they locked into place on the stab. For glue Jim insisted on using epoxy so the holes where he drilled too deep would be filled up with a solid material. After the struts set up over night, I dabbed a drop of CA on each joint just to cover whatever area the epoxy may have missed. The whole process is simple, really, but difficult to explain in text. Check the photos.


Now the stabilizer is so stiff I imagine in any disaster at least that much will come out unscathed. This is one less potential failure that we will have to be concerned with. At the speeds we are anticipating, about all I have time to think about is keeping the plane out of the ground, so I don't need to be distracted by parts falling off.

Flutter Prevention
Flutter is definitely the most deadly potential problem will face as we push the Aspera forward to greater and greater speeds. For going ballistic, we really need to go with smaller control surfaces, but remember, we want to take the same plane you can buy and merely hotrod it with a few simple tricks. Ripping the control surfaces off existing Aperas isn't really an option, so we will need to press old school flutter prevention techniques into service for this one.

Aileron flutter generally sets in at the outboard aileron tip, near the wingtip itself. Since I am not an engineer I am at a loss to explain it exactly, but a wing creates it's most disruptive turbulence at the outboard tip. If the aileron extends out as far as the wingtip, it's in that turbulence, which wrenches the aileron in an oscillating fashion, which creates more turbulence, which creates more wrenching....and you can see it's the highway to hell for your beloved Aspera.

Fortunately (and most likely the result of excellent engineering) the Aspera's wingtips extend back to flush with the trailing edge of the aileron, and the tip itself is so wide that the outboard aileron tip is a full 1" inboard of the outer wingtip. This gets the aileron out of the most disruptive turbulence and greatly reduces the chances of flutter.

And yes, the horizontal stabilizer has tips designed the same way to shield the elevator tips from the turbulence.

From our experience manufacturing our own stick ARFs in the late 80s, even more critical was making sure we had not only a tight hinge line, but to seal it as well. You can do this many ways, but we have found that clear Monokote is the most durable and easy to work with material we have. As you can see in the photos, the best way is to cut a strip that will overlap both the trailing edge of the wing and the leading edge of the control surface with the surface fully deflected. Once you get the edges sealed down, it's a simple matter to shrink up any excess with your covering iron.


Then, back off holding in so much deflection and tuck the covering into the hinge line with your trim iron. Now, be careful that you don't shove so much in there that it tightens up and restricts movement. Generally, even if you plan to 3D the thing, you still won't use up all of the movement the hinges allow if you do it right.

Not only is this an effective method, but it is nearly invisible. if you look at the picture of my finished aileron, you can't even see it. In person it is a little more obvious, which is why we do it on the bottom. Still, even then you would have to know it's there to see it.


Aside from being lazy, I can't find a reason not to do this to every plane I own.

Other things to watch out for are making sure you have the stiffest linkages possible, and having zero slop in the servo gears, servo arm holes, or control horns. The less the turbulence can oscillate the surface, the better chance you have of not suffering flutter.

When I built my own Aspera, I replaced the standard control horns with beefier Goldberg 1/2A control horns, and used z-bends at the servo arms instead of the EZ keepers. Since I have a nitro background, I was leery of anything that wasn't bullet proof, and while the standard Aspera didn't need to be so rugged, these precautions have reduced a lot of the work I would have otherwise needed to do setting her up for ballistic flight.

It also seems that once you flutter a plane really hard it becomes even easier to do it the next time. I'm not an engineer so I don't know exactly why, but I suspect that fluttering fatigues the wood and makes it easier for the turbulence to twist and oscillate again. I didn't arrive at this by scientific study, but when developing our flutter prone stick ARFs, I did find this to be a very noticeable pattern. When you fluttered them real bad once or twice, you either replaced that control surface or you were surely going to have it rip off the airplane in flight. It's better to prevent the flutter to start with than to have to chase it once it sets in.

We are also toying with the idea of running some carbon fiber rod over the elevator push rod. This will stiffen it up considerably, but I am loathe to make the airplane any more complicated than it already is. Then again, maybe I am just lazy and making excuses.

So, in general, outside of the stabilizer braces, everything else is just plain common sense procedure. We have gotten lazy with ARFs, but if you don't do these things you can eventually expect trouble. The Aspera is a solid design, but you've got to put it together right if you are going to push it this hard.

Streamlining

Since we are trying to eliminate every last obstacle to going fast, we need to look at drag. There is going to be a lot of air blasting over this plane, so we need to look at anything that can disrupt that flow.

When we originally set the airplane up, we didn't know which way we were going to go on control surface setup, so we left the servo control arms long. Here we have snipped them off and rounded it off as much as possible. It might not seem like much, but anything sticking out at these speeds is like a parachute.


You will also notice in some of the previous pictures that the bolts holding the control horns on have been cut as close as possible. This is really nitpicking, but again, at these speed you are looking for any little nub to trim that you can.

The Aspera was extremely clean to begin with, so there wasn't much to do in streamlining. After thing quiet down a bit we will look into air management inside the plane. In Florida, you have to get airflow just right or everything is going to broil. right now it's early September, and while it's cooling off some, it's still uncomfortably warm outside.

Sometime in October conditions will be cool enough for taping off the vents, and jamming on enough prop to amp the motor a bit past it's recommended max current draw. We hope to have a radar gun by then, and Ben's calculations are the 140mph might be possible.

I think if the extreme Flight guys ever see this article, my poor little 2814 will probably have a void warranty.

While on the subject of streamlining, the canopy will definately be an issue. My plane is running without the two front canopy magnets, but so far it hasn't been a problem except for the time I forgot to strap the battery down! I've got a nice hatch latch sitting here, but for the first few flights we will probably just tape the rear of the canopy down.

Last Minute
With the speeds we are anticipating, any accident with the Aspera isn't going to be very pretty. With this in mind, we have made a very conserted effort to go over every single square inch of the plane to make sure things are 100% perfect. Last minute tasks include checking every screw on the plane to make sure it's tight, making sure all the plugs are fully pushed into the receiver, and that all the wiring spaghetti is nearly tucked away. On all the control horns we applied a drop of CA to lock in the securing bolts, and new fuel tubing was cut to 1/4" links and pushed over the clevices to keep them squeezed shut. I guess I have checked the wing retention bolts probably about 50 times by now.

If you are ever going to be obsessive, this is the time to do it. This whole project has been extreme, goofey, irreverant fun, but when it comes to preparing and flying the plane, it's time to get responsible. We have a good idea what we are getting into, but there are still a lot of unknown variables. I have a lot of faith in the airframe's ability to go to the next level and stay stable. What we have addressed is airframe and ancillary integrity. Basically, we just had to make everything as right as we know how.

Time to drop the hammer and see what happens.




Man, is this baby ever sick fast. It's just plain scary.

We got the TP charger today and we had enough time to top off one of the Klondike bars and grab a flight before sundown. I was pretty nervous going into this because we have pretty cramped airspace restrictions and a really grumpy neighbor who loves confrontation. It's been awhile since I have flown a seriously fast airplane, and I know for a fact that age hasn't made me any better.

I was so nervous that I just wanted to get it done. We have put a lot of work into this project and probably checked everything 50 times. I could have gone on and on and make myself crazy worrying about what I may have overlooked, but it was getting ridiculous. If the plane wasnt right by now, I don't have any business working on them anymore.

The Aspera rolled out about five feet before take off, but remember we are going for speed, not pulling power. However, once she was up, the little torque motor let out a tortured scream and the Aspera accelerated even faster than I had ever seen it go. I flew her around a lap to check trim, and she needed a couple of clicks of down. This didn't surprise me because now she's going a lot faster and the wing is producing a lot more lift.

First trip out of a big split S down the runway left everyone moaning "Whoooa!" It even scared me it was so fast. About every three seconds I would have to think about turning her around because she was rocketing around the field so fast that there simply wasn't enough room. I checked the vertical pulling power and held her nose up for about 8 seconds, and she was so tiny by then that I had to spin her down. She was so far up there I couldn't tell which way she was going.

So, we haven't located a radar gun yet, but I'm estimating we have got a good, solid, no BS 110mph going here. We've had Largo police clock my big Pulse XT46 at 101mph, and now the Aspera is a lot faster.... a lot faster. So, I'm guessing part of that is that the smaller aircraft appears faster, but still.....the thing is so sick that I probably won't be able to responsibly fly it at my field again.

That, and honestly, I'm a little bit afraid of it. It's just too dammed fast to fly with a neighborhood only about 1000 feet away. Maybe that sounds a little paranoid, but 1000 feet is nothing at the speeds This baby is travelling now.

It's just siiiiiiiiiiiick.

Unfortunately Captain Ben had another committment and we didn't get any video, but the beast lives and will fly again. Hopefully we can get some video tomorrow or the next day. I'll have to US Mail it Rob on a DVD, and that will take a few days. I suppose we can count on maybe next Friday or so.

At this point in the project I'm not sure we need to stress the power system out any more. The batteries run very cool and it was a hot day today. You could hold the pack in your hand and it wasn't even uncomfortable. The motor was a little hotter, and while it was unconfortable to stick my finger in there on the motor, it wasn't painful or anything.

We ran her on an APC 10/8E, and I kept it hammered for nearly 10 minutes. The battery was just beginning to lose it's edge a little at around 10 minutes, so I figured why push it when we still have to get it videoed and radar readings.

I landed after about three minutes to check the battery heat, but after that I just poured the coals to it to see how bad the temps would get. They weren't real bad, so I suspect we can go up on the prop a little. Still, the thing is an absolute scary rocket just the way it is. We may have to schedule some test time at Wymauma and see just how fast we can go. Judging by the low temps and modest amp draw, I know we can tweak her down a bit more. I suspect there's another 20 mph left in her.

Worth noting is that you can now hear the plane whistle when you bring it by. It's loud. That's the first think you hear when the plane is approaching. Not only can you hear the air rushing over the plane, but now the air going through the motor is much more audible. The Torque 2814 sort of has it's own sound anyway, and part of that is the way it pulls air into itself and whooshes it out. The growl is deeper and the whoosh is much more pronounced now. The thing sounds absolutely awesome.


Finally got two more flights in calmer conditions and it the Aspera has absolutely been transformed. Before it was downright scarey, but the conditions were impossible. In saner conditions the Aspera is dead rock solid and the extra grunt locks her hard into a groove. The plane tracks so much better at the higher velocities that it is more like a big 60 sized nitro monster than an electric.

Perhaps I've gotten used to the speed a little more, but I've no fear of the plane at all. Certainly it's fast, but it's very manageable. I never fel like the plane was going to get away from me. I thought the extra speed might make her a little flighty, because after all, she is a light airplane. However, the extra grunt and blistering speed has made her even better.

Point shoot...point, shoot. The plane is even more stable than before, but things do happen sooner. You have to be concious of the speed, especially with our tight airspace restrictions, but the speed itself isn't a problem. The Aspera at these speeds feels even better and more secure than anything I have flown since my 60 size nitro Curare. In fact, I'de have to say now the Aspera is better than the Curare.

Sorry Hanno.

I know that I keep using the tern to the point of overkill (which is the whole point of this project), but she is absolutely vise-like "locked in."

The only adjustment I have had to make has been in my own flying. I just had to step it up and stay further ahead of the plane. The plane isn't the problem. It's my old reflexes that weren't up to snuff (The Aspera has always been better than I could fly her). I almost put her in the first day because the plane went by me so fast that I lost track of her. That was sort of the wakeup call that we aren't playing a game anymore and we are now back into extremely serious airplanes......and I find that pretty thrilling.

So, it's a little early for a final verdict, but as much as I already loved the Aspera, she is even better now. The average sport pilot will love the plane with the standard power package, but you learn so much, so fast with the Aspera that pretty soon you will be ready for more. What we have tried to do is find a way to take the existing Asperas to the next level with a minimum of expense and work. It may take some time to refine the whole package, but I think we've got a whole new airplane here for only $130 or so.

For now, though, by far and away I've got the baddest plane most people around here have ever seen. We come out and what we are doing is stinking outrageous, but the Aspera is so good that it's easy.


Thanks again to Rob at ADChobbystore for web hosting and video editing, Here's video from the first day out:

VIDEO: http://www.adchobbystore.com/pics-vi...sticaspera.htm




[CENTER][/CENTER

Charley

My Feedback: (2)

Doc,

You have gone completely 'round the bend!

Cheers,

CR

CoytAW

wow... that is beyond cool. i hope to god that you dont hit any birds with it. the kinetic forces alone would destroy the earth. wow.