DS plane of choice?

[Craig Toutolmin]

What are you flying this year to set a new personal best for speed? If you are building, do you have any clever ideas to make your plane DS proof?

Craig

[Reed]

Hey Craig,

Still haven't started my DS baby but it's on my mind. Here are my parameters

1) speed - I want this thing to do at least 150

2) building ease - I have to be able to use most of my current knowledge to build it because I don't have much time to build and I want it in the air ASAP. This means using a lot of stuff I've learned from PSS with a few very helpful hints from you and others.

3) size - One piece wing. Through intense study and careful scientific analysis I've determined that an 86" wing will fit between the passenger side floor and the back window of a 1989 Toyota Camry.

4) strength - it's DS for goodness sake and I've watched what you guys put these planes through.

All of these factors are related. For example, a bigger wing would go faster but a shorter, one-piece wing is easier to make strong. It's also a quicker build. I'm not concerned with setting world-records, but I do want to increase my personal bests and have a plane that I have confidence in.

Some thoughts on building:

1) fuse strength - I'll be building up this fuse using a mix of trad and somewhat experimental techniques. I need a very stiff fuse (said the trollop to the vicar), especially in the lateral axis along the boom and I have some ideas which would take too long to describe here. It also needs to be big enough to hold ballast that'll get the plane up to at least 25 oz wingloading (starting from about 18 oz or so).

2) wing strength - carbon on a bias for torsional rigidity, topped with 1/64th ply just to make the finish easy. I'll probably press the wings because I'm cheap and I've never bagged a wing. Spar will be 1/2" endgrain balsa from top skin to bottom skin with carbon caps. I'm tempted to sandwich some carbon or ply in the balsa but I'm not sure it'll help all that much. I'll almost certainly wrap it in a carbon sleeve to give it a nice shear web. Caps will be layers of uni cf running from 20 layers or so at the upper root to 8 or 10 at the tip - half of all that on the bottom. Haven't decided about the LE yet.

3) set-up - against all rationality I'm pretty determined to only use ailerons on this plane. Easier, cheaper, faster, and I'm so used to flying PSS with no glide slope adjustments that I think with some spoileron in I'll be able to land this thing. I'm not worried about having flaps for camber on light days because I don't often fly on light days. Standard tail, mainly because it's easier for me to build and make straight. Tail feathers will be about 18% of wing.

4) L/D - have a pretty good idea what airfoil I'm using and some idea for the planform but I won't go into all that here. I do intend to cut down on drag as much as possible by cutting down on wetted area, using servo covers, smoothing all surfaces to high gloss and cleaning up the tail section. No external tail linkages and - wait for it - no rudder! I may regret this but if I do it'll be easy enough to add later. Main reason is that I use absolutely no rudder when DSing and it'll make the plane faster to build with fewer surfaces to flutter and less drag.

Those are my thoughts so far. I have a PSS Aircobra on the bench right now but this one is next up and I hope to have it finished by early May.

[bjaffee]

I'm currently flying an Opus V. Been DS'ing it for nearly every weekend for the past 2 years, in fact. I still haven't past 150mph on radar. 141 is my fastest actual clocked speed, though I think I've probably gotten to or close to 150 when the gun wasnt there (of course!).

Anyway, with 150+ in mind, I ordered a Sting DS last year, and took delivery of it in November. A friend of mine has the first Sting DS, and so far it's been good up to 177mph, so it seemed like a proven commodity to me.

Unfortunately, I've only been able to fly mine 4 or 5 times since I got it, due to some weird weather. I already love it, though. It's actually my first big (~3m) plane..perhaps they all fly like this...wow, it feels so smooth and stable while DS'ing. It makes my Opus feel like a 60" plane by comparison.

[Craig Toutolmin]

Hey Reed,

You pretty much described my green Circle Jerk in size, skin lay up and surface controls. It is a really fun plane to fly, but it is really hard to land it at Sibley. It is 20 oz/ft^2 dry and I've only wanted ballast at compression slopes. I'd recommend adding the bagging equipment. After bagging you can press/post cure.

How much di, poly di, or polyhedral?

Craig

[Reed]

"How much di, poly di, or polyhedral?"

Hmmm, that's a good question. I tend to build pretty flat but for circles a nice dihedral (again, for simplicity's sake) would be helpul for holding a solid line. I'm open to suggestions.

Now that I think of it, maybe I'll just angle the outer panels because I could build the center section as a flat piece and I wouldn't have to be quite as worried about the strength of the angle joints on the outer panels where the bending loads aren't as great. Wouldn't be that much more work and it would probably do wonders for the handling.

So you say it's time to start bagging, eh? Is that because of the results or the ease of building?

[Craig Toutolmin]

3-4 deg of poly dihedral makes a world of difference in handling. I built one plane with a three piece wing and could use straight or 4 deg joiners. The plane is much easier to fly with dihedral joiners. So much so that it is now a one piece wing with poly dihedral.

You'll get better bonding and more efficient use of epoxy with bagging.

[Ade]

I am still beating the crap out of my acacia :-) Had an excellent day up at rushup edge last weekend. 20mph over the front tight boundary and super smooth air above and below the boundary. The acacia just couldn't handle the speed build up after a couple of tight well placed circuits.

All that should change soon tho. Espen has just put one of his special DS layup Opus Vs in the post to me. I can't wait to get my hands on this beast :-)

Whats your opinion on ballast for DSing? I have never needed more than a few slugs to increase the momentum when it gets rough. More than that increases the stresses on the model..

what do you think?

Ade

[Craig Toutolmin]

The Opus is a great plane. I'm not sure if the version that Bob Bingham was flying at the DS fest was a DS version, but it got to speed very quickly - almost too quickly for Bob :eek:. On a negative note, it had an unacceptable amount of wing bend. Since Espen was at the event I'm sure he has taken care of this problem for the current models. I'd like to see a scaled up version (100") so that it is not stuck in between the 60" and 100" classes. This is a big disadvantage.

I'm not sure this counts as ballasting since the weight in built into the plane as extra strength. In general, and in strong conditions heavier wingloadings seem to be advantagious. In the dense air of Cape Blanco Tom's Mojo did very well at 20 oz/ft^2 and Dave's Wizard BP was around 18. Tom's Mojo also does very well at Parker (3800' elevation). In one flight he hit 176 a half dozen times with a 17-18 0z/ft^2 version. The heavier one was cruzing figure eights for several minutes at 135. It is a VERY impressive plane.

A thought on ballasting.?. While the wingloading is greater the flight pattern is more gentle (lower cl) so there might be a wash in terms of weight vs. aero load.

[Ade]

My observations with Foamies which probably shows the performance increases better due to their higher drag is that ballast only really increases the diameter of the turn and thus the time between the kicks. If you try to maintain the size of the circuit at the higher weight the drag just goes up due to the higer angle of attack needed to produce the extra lift to get round the turn.

With the acacia I pretty much only use ballast where the seperation gets too rough in higher winds at whumpcrump. It just stops the model getting thrown around so much but the wing bend round the bottom turn is alarming! It doesn't seem to increase speed.

In 20mph at Rushup the acacia wasn't getting thrown around but the model was getting a little stressed to say the least not to mention the occasional flutter.

I am looking for tips on flutter reduction. I am thinking long servo and surface horns? What about mass balancing of the control surfaces?

Ade

[bjaffee]

Hmmm...nice thing about the Opus is that, at 2 meters, its a lot more affordable then an unlimited (~100") type DS plane.

I still kinda wish at the DS fest that they had arbitrarily limited the middle size class to 80" or something, so it would have been more of a shootout between the 2 meter class slopers, like the Opus and Blade (and maybe the Extreme next year...my friend just ordered DS version of the new molded one). It just seems like anything close to 100" (like the Wizard) is really more of an unlimited plane. Just IMO, anyway.

I am curious about the new "DS version," of the Opus and whether it is truely stronger then the current version, or if they just made the current version lighter, and now offer a DS version with the same layup as previous one (did that make sense?). I know there's also a total carbon skin version as well, but its hard to get. If the finished plane weighs around 48oz, its the same as what I got.

Concerning ballast. At hill I fly at, I usually ballast for DS at about 50-75% of what I would use for the front side conditions at the time. Not sure how I came up with that formula, but it seems to work good for me.

[Reed]

Isn't anyone else crazy enough to try building their own DS plane!? C'mon guys, I'm feeling like a total nerd here. A nerd who makes enough money to buy fiberglass, balsa, ply, cf, and kevlar but not enough to buy a big, beefy moldy.

Of course, counting up the hours I spend building I could probably buy 3 or 4 of those planes for what I put into one of my own half-ass designs. But that would be so obvious.

[bjaffee]

I've made enough of a mess in my one bedroom apartment just building ARFs! (don't think I'll get my security deposit back) Maybe when I have my own house and a garage/hobby room I'll start building my own. Until then, it's a logistical nightmare.

[Ade]

There are some excellent cheap DS models around. Opus, Miraj, any of the 60" moulded models.

Ade

[ShredAir]

Originally posted by bjaffee
I still kinda wish at the DS fest that they had arbitrarily limited the middle size class to 80" or something
As far as I'm concerned, DS classes are completely arbitrary, made up on the spot, and bound by no rules whatsoever. I remember that the class-deliniations of the 2002 event caused a lot of discussion even then. Personally, I'd be happy with just two classes: up to 2 meters and open. Note that "open" is just that: you can fly a 6" disk, or a 10-meter ETA, or whatever you want, so long as you do so competently and safely.
Speaking of which, safety measures and new gear is all we'll test this year. But I'm confident we'll be happy enough with the results, that nothing will stand in the way of the 2nd "official" DSlope Fest in 2004.

Dieter Mahlein
http://shredair.com

[bjaffee]

Dieter,

I don't know how realistic this is, but I was thinking in terms of the manufacturing devlopments that the classes might spur. I know there's still a pretty limited demand for purpose-built DS planes, but there are definitely more available out there now then there were before the DS Fest. I was thinking that a win in any particular class could prompt some of the manufacturers to develop DS version of their planes that fit that particular class, rather then only making very expensive unlimited DS planes.

[Craig Toutolmin]

There is a big performance jump from 60" to 80" and 80" to 100".

If you look at all the speed information from all the sites and conditions over that last few years you'll find the following approximate max speeds.

60" - 140 mph
80" - 165 mph
100+" - 185 mph

Note that only one plane has flown over 180 and stayed together. While the speed vs span curve still has a good slope, what will limit the 100" plus class is the information I received from Olliver Wilson recently.


"The structural performance of dynamic soarers is limited by the fact that for a given structural configuration and material, strength goes up as the square of the linear dimension but weight goes up as the cube of the linear dimension."

The smaller planes are really solid performers that seem to be limited by their efficiency and not their structural integrity. I would recommend to have official classes for 60", 80" and unlimited. I'd like to see more 80" production planes. It is a really fun sized plane to fly.

[bjaffee]

Originally posted by Craig Toutolmin

I'd like to see more 80" production planes. It is a really fun sized plane to fly. [/B]

Yep, I think this class is really under-represented. There's such a big glut of 60" planes out there!

[Ade]

What is the current range of DS capable 2metre ish models? First 2 that come to mind is;

Opus,
AldiJ,

My heavy layup Opus from Espen soon :-)

Ade

[bjaffee]

Originally posted by Ade
What is the current range of DS capable 2metre ish models? First 2 that come to mind is;

Opus,
AldiJ,


The carbon skin Blade (which I assume is DS'able).

The (now molded) McLean Extreme should be nice (if there's an Opus beater, I assume this would be the most likely one).

The Essoraj (which isn't made anymore AFAIK).

Then there's a few planes that, aerodynamically would be good DS planes, but suffer from being a bit too much on the "soft" side, such as the NSP Flash 2 meter.

The new NSP/Vallenta Swallow looks nice, but I don't know much about it's construction (if the quoted 35oz flying weight is to believed, I imagine it isn't too strongly built).

[Ade]

The essoraj is still available but special order only apparently.

The one I flew was brutally strong and excellent elevator response. However in the conditions needed to really get this model to perform turbulence was a problem the model needed a lot of work to keep her on line.

I have heard the Opus flies big so fingers crossed it should be as strong as the Essoraj with better speed and of course has flaps so it should actually be landable ontop of those tight landing spots that make up so many of our DS hills.

Ade

[Reed]

Yesterday at Sibley I watched Tom Seitz tear the nose off the Mojo on the bottom turn. At the time he was taking turns that some of the vets said were faster than anything they'd seen, faster than the 186mph world record according to some. It was certainly the most astonishing DS I've seen so far (though I've seen Craig T. at blinding speed over at Shell Ridge) and it did three things to my perception:

1) scared the crap out of me

2) made me more in need of a DS machine than ever

3) gave me even greater impetus to build strong, strong, and stronger. Not for the plane's sake, but for the sake of anyone witnessing.

Tom had been in the air for about 10 minutes when the plane suddenly broke loose from controlled flight. Without forward ballast, it immediately lost all speed and fluttered to the ground. The nose was found some distance away and the repairs will be fairly simple. The Mojo is one stout beast, but now we know of another place these planes can fail - just in front of the LE! Wow.

[hkrussell]

Joined in a bit late but not too late I hope...
It's interesting looking at the speed figures Craig posted for the different sized planes.

"There is a big performance jump from 60" to 80" and 80" to 100".

If you look at all the speed information from all the sites and conditions over that
last few years you'll find the following approximate max speeds.

60" - 140 mph
80" - 165 mph
100+" - 185 mph

Note that only one plane has flown over 180 and stayed together. While the speed
vs span curve still has a good slope, what will limit the 100" plus class is the
information I received from Olliver Wilson recently."


I think it was Scott Hewitt that had the E2V that went 183 at the DS fest, and it blew up bad. That seems to confirm the belief that the big planes, though generally faster than the small planes, can't handle the stresses of DS'ing. The Mojo and 2X Wizard are both 90"-100" planes that went faster and even thought the 2X lost a tail, it didn't suffer the damage of the E2V.

I think the fastest DS planes will be in the 100-110" range, unless someone builds a BOMBER 130"-150" plane. That large a plane would be a POC until it got to speed then if it held together might go pretty good. Really tough to build though, and expensive to just fly 3-4 times a year.

[ShredAir]

Something else is going on here which matters more than size: No plane initially designed for F3F/B will be the "DS plane of choice" no matter how much carbon one stuffs into it. F3F/B planes are designed to work well on the front of the slope in varying conditions, and no matter what you do to them, they'll hit a wall or shed something between 120 and 200 mph.

To begin with, their control surfaces are too numerous, too big, and improperly actuated. Their airfoils and planforms are compromises in which DS is not even a factor. No commercially available plane (right now) can hope to be the DS plane of choice.

The DS plane of choice will be a friggin DOG to fly on the front side. It'll have an airfoil and planform which barely start working at 200 mph and are good for twice that. Control surfaces will be small and push-pull actuated, maybe with servos doubled up, the elevator especially. There will be only ailerons and elevator.

You have to build such a plane; it does not exist commercially. The reason for that is not a lack of know-how or enthusiasm, but simply that commercial builders do not yet see a market in such a plane.

Dieter Mahlein
http://shredair.com

[bjaffee]

Hmm...well, it can't be the plane of choice if it doesn't exist. I'm sure we'll eventually see something as extreme as you say.

I don't neccessarily think that every DS pilot is going for 300mph though. Personally, I just want a plane that will be reasonably solid at over 150mph. At the slope I fly at, those speeds are more the exception then the rule anyway (169mph is the local record at the moment), so it's not too hard to find a DS modified F3F plane that fits the bill. If I flew at Blanco or Parker every weekend, I might think differently. :)

[Craig Toutolmin]

The sad fact is that the majority of "DS" pilots fly foam. They will work their way up to a Bluto or whatever is the fastest foamie. The good thing is that the people that are interested in this thread are all talking glass composite. They have moved on from foam!!!!!!!!!!!!!!!!!!! As personal bests ratchet upward more people will be interested in faster planes. There are plenty of planes out there that can crack 150 and still compete in F3F. This is good value. Others planes like the DS Sting and BP Wizard are specific, non-optimized DS planes that are poor F3F performers (unless you dive the Sting 8-) ). The smaller planes like the Wizard are still great sport planes and are a good value. It is all about what your goal is in terms of value and speed.

I am interested in the design/pilot challenge that DS offers. To rachet up to the next level of speed requires a plane that cannot be bought. As for the current options for DS planes, I won't trust just any builder with the liability that I will assume when I fly their plane. I've seen the inside of some 100"> DS planes and was shocked. Not many of the manufacturers are up to the task! Most have major design flaws.

The information and exposure gained from the DS Fests help to advance designs. Eventually there will be a proper high speed DS plane that will be a slope classic. Who cares if you can only fly it a couple times a year. As long as you have one to fly when the conditions are on! This plane will sell plenty of models. Most will probably be trophies. I don't believe this niche of slope flyer will be as trendy as F3F and a great design could last for many years. What is 200 mph worth?

Craig

[bjaffee]

I actually use my DS Sting as a sport plane, in that I intend to fly it as my regular slope plane. Despite it's weight, it's light lift capabilities aren't any worse then something my unballasted Opus, which I can fly about 90% of the time. It's still well under the weight of a fully ballasted Sting, so I don't see why it couldn't be used for F3F if the conditions aren't too light.

[Craig Toutolmin]

Whether or not a plane can fly is not the basic requirement for F3F. The extra weight in the extremities reduces the handling qualities of the planes. One local flyer has the DS version of everything. I'm serious! They all have sluggish handling compared to their F3F or F3B version, and non have been successful in F3F.

[bjaffee]

Certainly I'm not saying they will work as well. My friend has had both a non-carbon Sting and a DS Sting, and the non-DS one definitely turned better, but he's still managed sub-40 times with the DS. I'm not saying it's going to win, but that's not what he bought it for (nor did I).

Anyway, I'm not sure what differece that makes to the original question. Bottom line is, not all of us have the time, resources or ability to make our own DS planes. As long as that's true, the modified F3F plane make the most sense as a "DS plane of choice." You can't chose from something that doesn't yet exist.

[Craig Toutolmin]

In this thread the point was made as to why you would want a plane that you could only fly a few times per year (low $/flight value). This is not reasonable for most people. The larger F3F/DS hybrids as Dieter mentioned are a compromise that won't attain the higher speed potential of DS. However, they can be used in other tasks and thus increase the $/flight value.

Once you back off from DS specific planes you compromise something. Once you overbuild a F3F you compromise something. Sub Forty is not a measure of a planes' F3F ability. How many races it has won in a variety of conditions is what defines its F3F ability. As for F3F speed, you have to look below 35 seconds.

Again, if you read the thread you see the statement that Ollie makes concerning the limitations of DS planes .... weight. It is much easier to make a smaller plane as strong as a larger plane and have a lighter wing loading. This is why the single carbon Wizard can DS 150 mph, crack a 32 sec F3F and is reasonably competitive in F3F over a variety conditions. This is also what makes the plane a better sport plane, because it retians more of its handling charactoristics than the larger F3F/DS planes.

[bjaffee]

Originally posted by Craig Toutolmin
In this thread the point was made as to why you would want a plane that you could only fly a few times per year (low $/flight value). This is not reasonable for most people. The larger F3F/DS hybrids as Dieter mentioned are a compromise that won't attain the higher speed potential of DS. However, they can be used in other tasks and thus increase the $/flight value.

Well yes, that's what I'm trying to say. I guess if you're REALLY into F3F, and can have only one airplane, that might be a problem, but since I'm not, it isn't.

Anyway, I just want a plane that will hold up reasonably well in the current upper speed range of the F3F planes, and will also be a fun (albeit expensive) sport plane. So far the Sting is working for me.

[Craig Toutolmin]

Brett,

Your attendence record at F3F events is enough to establish your level of interest. If you are happy with your plane, good deal! If you want to add something more constructive to the DS discussion, perhaps you would describe the triple carbon scheme? What weight carbon? Lay-up schedule? What are the size of the joiners? Fuse/Tail enhancements, lay-up? Spar(s) contruction and size? Control surface closeouts? What makes this plane so good?

[bjaffee]

Jeez, man are you taking this personally? The topic is "what is your DS plane of choice," not "what is Craig's DS plane of choice." Or am I not god-like enough to have an opinion on that?

And like I said, not all of us have the ability or the resources to build a DS plane from scratch. Does that mean I don't get a choice?

As for the Sting DS...you can ask the guys at VV about the specifics. I'm not a designer and I'm not going to get in a pissing match with you about it.

What makes it so good...why did I get one? My friend has the first Sting DS. He's been flying it for around a year. At this point, it's been as fast as 177mph at Parker, and I have no doubt that it could go faster. I've seen the plane fly on nearly every weekend for the past year in almost every conceivable condition, and it is a solid performer. It's smooth, fast, and obviously very strong.

That's why I chose mine. Sorry if you don't think my opinion is constructive or has any value.

[shoe]

errr yeeah :rolleyes:

so back to talking about toy airplanes...

Craig, I liked the article on rc-soar.com about your X-plane model. I'm curious, how did that come out? What did you learn from it?

[Craig Toutolmin]

That was a couple years ago. There is a little footage of it flying in "Lift Ticket". Scott is flying a F3B Eagle that I sold him and we are DSing at the same time. The main difference in the two planes was the flying weight. His was around 15 oz wing loading and mine around 20. The X-Plane planform was based roughly on the F3B Eagle. Anyway, the lighter plane flew small circles and the heavier plane flew big circles. The plane eventually failed at Blanco. The carbon joiners had been replaced with chromoly because they were too flexible. This put too much stress on the joiner box/spar juction and the whole thing tore out of the center section. A very impressive failure. The tip panel hit the center panel with such force that the fuse broke into three pieces. Lots of bits everywhere.

I went back to a 90" plane to see if I could build that strong enough. Tom built his Mojo concurrently as we both went through the mental gymnastics of molding three piece fuses and two part wing bagging. The 90" wing was more than strong enough but the tail was a problem. Tom's plane consistantly outperformed it. He had a similar lift distribution but had larger chords, less camber and a stronger tail. The third plane was smaller yet at 81" and has proven to take all the abuse that it is given. The v-tail problem was solved with plug-n V's. Now, after two years its time to take another stab at 124".

[speedster]

Carbon NYX