Scissor Wing 2X (old school 1980) [Dynasoar Rocketry]

[Crawf56]

To continue my theme of "starting new projects before I finish existing projects", I am starting on a Dynasoar Rocketry "Scissor Wing 2X".

The "2X" means it is twice as big as the original Scissor Wing from Estes: my Semroc Scissor Wing has a 15-1/2 inch wingspan, while the Dynasoar 2X Scissor Wing has a 27 inch wingspan.

 

[Crawf56]

Dynasoar Rocketry figured out that, from an aerodynamic stand point, the Scissor Wing doesn't really have to 'scissor'.

 

[burkefj]

Right, the added weight of a drop unit, or an R/C controlled swing mechansim offset any altitude boost potential and glide improvement, especially compared with low thrust E-6 motors where you can simply steer it, it was just simpler and lighter and looked good.

 

[TheAviator]

Right, the added weight of a drop unit, or an R/C controlled swing mechansim offset any altitude boost potential and glide improvement, especially compared with low thrust E-6 motors where you can simply steer it, it was just simpler and lighter and looked good.

Sure, but big free-flight birds are also cool. There's room in this giant hobby for everything! Totally looking forward to this build.

 

[Crawf56]

However, I hope to make a pivoting Scissor Wing. [It is the Way.]

But rather than the later design (2004?), I hope to use the old 1970''s design.

 

[Cape Byron]

Every time I look at the Scissor Wing these days it screams "3D printed rotation mechanism, please!"

 

[Crawf56]

Here is the older instructions for the Scissor Wing.

 

[burkefj]

Here are some better boost/glide videos




I would not try to convert the dynasoar kit into a swing wing, the foam is just not strong enough to support an opening at fast speed and you can't control the speed as much with a folded wing boost. I've also moved the wing back to help boost/glide cg so it is not in the right place to clear the pivoting wing, which means you'd need extra nose weight for glide which will be reduced due to the heavier weight. You would also need some way to boost with spin to keep it straight since I don't think you will be able to steer it with the wing folded with the rc controls to any great extent other than maybe full roll input, or you'd need to redesign everything for a boost pod with extra fins for stability and ejects... if doing an upscale scissor wing, which has been done up to G motors, I'd just use a balsa wing and upscale everything.

 

[Crawf56]

No doubt that burkefj is correct. But I have some ideas.....

• I will use a micro servo at the nose to 'release' the Wing. A pop pod will not be needed.
• I will move the Elevon servos farther from the Tail (closer to the wing pivot point), to reduce tail weight.
• I will use some 1/64th inch plywood to aid Wing center section strength.

And it still may not work....

 

[burkefj]

No doubt that burkefj is correct. But I have some ideas.....

• I will use a micro servo at the nose to 'release' the Wing. A pop pod will not be needed.
• I will move the Elevon servos farther from the Tail (closer to the wing pivot point), to reduce tail weight.
• I will use some 1/64th inch plywood to aid Wing center section strength.

And it still may not work....

How are you going to get a straight boost with the vertical stab and wing drag? Are you going to put full roll input on boost to get it to spiral? I simmed that and it cost me about 100' in altitude in the sim but was the only way I could think of to get it to be more or less straight under boost...

 

[Crawf56]

How are you going to get a straight boost with the vertical stab and wing drag? Are you going to put full roll input on boost to get it to spiral? I simmed that and it cost me about 100' in altitude in the sim but was the only way I could think of to get it to be more or less straight under boost...

Had thought I would give some Down Elevator.

I also admit that my criteria for a "successful flight" is pretty low. If it can fly again after the first flight, I will be happy.

 

[burkefj]

At least have someone there to video

 

[TheAviator]

How are you going to get a straight boost with the vertical stab and wing drag? Are you going to put full roll input on boost to get it to spiral? I simmed that and it cost me about 100' in altitude in the sim but was the only way I could think of to get it to be more or less straight under boost...

I think you vastly over-estimate the effect of off-centerline drag. As long as you have sufficient fins and speed off the rail, you will be fine. I've flown all sorts of non-symmetric free-flight models with no problems.

 

[burkefj]

I think you vastly over-estimate the effect of off-centerline drag. As long as you have sufficient fins and speed off the rail, you will be fine. I've flown all sorts of non-symmetric free-flight models with no problems.

Brian, I don't know about "vastly" if that were true none of my airplane shaped models would require any thrustline offset from the wing line nor would they require some pitch trim on boost, in fact several require both because it was not possible to offset thrust line sufficiently to counter the drag. In fact on this model I offset the thrust line to be as high as possible and that gave me a perfect offset to the drag, on my original version the center mounted motor would pitch toward the top and required down trim. These are also 1/4" thick surfaces which have more drag than a typical rocket fin. In any case I'm just giving my suggestion, trying to actively fly it with the wing folded will be a problem I think because it will be hard to tell orientation without the wing extended especially if there is any roll. These are using my slow burn motors, higher speed/faster burn motors will make things worse.

Frank

 

[Crawf56]

From the Dynasoar instructions on the Scissor Wing (see second paragraph).

 

[burkefj]

From the Dynasoar instructions on the Scissor Wing (see second paragraph).

View attachment 575231

I seem so rational

 

[burkefj]

From the Dynasoar instructions on the Scissor Wing (see second paragraph).

View attachment 575231

You have version one which had a mid mounted motor and required down trim for boost, so I would definitely use some roll to offset the drag, the second run I used a high mounted motor and required no down trim for boost.

 

[Crawf56]

You have version one which had a mid mounted motor and required down trim for boost, so I would definitely use some roll to offset the drag, the second run I used a high mounted motor and required no down trim for boost.

For some reason, I have to let Dynasoar kits set for a year (or two) before I build them. I have had the Scissor Wing more than a year.

While I have the major tube and foam components, I have misplaced the bag with the motor mount, small strips of foam, small graphite rod, etc.

However, I have enough spare parts to make up for anything missing.

And the excellent instructions (typical of a Dynasoar kit) with pics will get me through the build.

 

[Crawf56]

"And so, it begins." - Kosh, Babylon 5

The main Wing is taped together, and must be glued. Also added main graphite rod.

 

[Crawf56]

Added secondary graphite rod.

 

[burkefj]

The parts bag might be inside one of the body tubes

 

[Crawf56]

The parts bag might be inside one of the body tubes

Not in a tube. The parts bag DID come with the kit.......because I recently misplaced it.

Like, about a month ago. I put the bag somewhere so that I would not loose it. I just wish I remembered where that was.....

 

[Crawf56]

More instruction info on the scissor version (see "b" & "c" below):

 

[burkefj]

More instruction info on the scissor version (see "b" & "c" below):

View attachment 575506

I would be cautious and use an F-12 to start and see how it holds up first...an E-18 might be kind of rough on it.

 

[Crawf56]

I would be cautious and use an F-12 to start and see how it holds up first...an E-18 might be kind of rough on it.

What about an E-6?

 

[burkefj]

What about an E-6?

You can try but I was afraid that might be a little slow and if you're trying to control pitch and roll manually it might not react fast enough keep it straight

 

[Crawf56]

Starting on the 3 inch diameter disks for the wings, from 1/16 inch plywood (from BalsaUSA). With the help of my scroll saw.

 

[Crawf56]

The Wing has a little hole for the center point (thanks, Dynasoar).

I am using a T-pin to get things located.

 

[Crawf56]

Epoxy and a strategically placed cup to attach the plywood.

 

[Crawf56]

Using the T pin to locate the second plywood disk. And more epoxy.