Estes kitbashing. "SuperViking"?

[Greever]

So for some reason I got the idea to take two Estes Viking kits, and make one long rocket with the parts. (long being a relative term)

I would use four fins, mounted low like a "normal" Viking.

Would the motor need to be mounted lower, or higher in the BT? Or would there be any CG issues at all?

Any and all help is greatly appreciated!

Andy Greever

 

[Bone Daddy]

Hey Greever

I just ran a quick sim using OpenRocket on a 2x long Estes Wizard.

I added a fin and tweaked the shape a bit to look like a viking. Stability looks great. I used a C6-7 which would shift the CG farther back than an 1/2A, A or B.

Why use 4 fins when you can use 5? If you can keep them pretty well aligned, the 5th fin will add to the stability of your rocket.

Mount the motor exactly as outlined in the instructions.

Post pixs when done.

Bones

 

[Greever]

That sounds good. I have allready built one Viking with 5 fins but haven't launched it yet.

The reason I was going to go with 4 is because I was going to use the fins from both kits to make "custom" fins. But if I can use 5 I will.

Pics huh? Considering how much I have learned lurking this forum I suppose it is the least I can do.

Time to go to Hobby-Lobby and get a second Viking kit!

"SuperViking", I love it!

Thank you for running it on a simulator, I appreciate that.

 

[gpoehlein]

A double length Viking will be even more stable than the original. And if the original is stable with 4 fins (actually, it is mostly stable with three except when the fins are mounted with the long edge to the BT and when using a C6) a double length model will be more so. Install the motor mount per the instructions.

 

[Bone Daddy]

Greever

OpenRocket is a freeware. Easy to learn. Someone probably can post the link or just Google it. It adds a whole new dimension to the hobby.

As gpoehlein pointed out, adding length generally improves stability as it pushes the CG forward and the CP back. Adding too much opens up a whole 'nother can of worms.

Bradycros

Check out my Size Matters thread in Scratch Built:

https://www.rocketryforum.com/showthread.php?t=16183

The goal was to build a rocket with the smallest fins feasible and still be stable. Playing around in OpenRocket I found that by adding a fifth and then a sixth fin, I could reduce the size of the fins considerably. My Bt-20 bird in the post has tiny fins. No one thinks it will be stable. Flies straight as an arrow.

From what I understand, tube fins can be modeled as 3 fins per tube. Tube fin aficionados tell me they are very stable. This seems to explain why removing the fins from a Super Neon (I think that's the rocket) doesn't affect the stability.

Bones

 

[FastCargo]

Well, to be fair, isn't pure surface area just one aspect of aerodynamic stability?

To take it to an extreme, you could have just 2 fins mounted on opposite sides of each other with the same overall surface area as a 3+ fins setup. But as soon as the rocket got slightly sideways in the wrong axis...

It's not just surface area, but amount of area presented to the relative wind in relation to the CG.

Which means, in theory, a multiple fin setup could be more stable than a few fin setup. Of course, as you decrease the size of all the fins, you may actually decrease the amount of surface area available in all the possible yaw situations, increase weight, increase drag due to fin/tube aero interactions, etc.

FC

 

[Captain Ron]

Well I learned over the years that fin span is more important that fin length. The ideal fin design is either the clipped delta or the trapezoidal design.
the Viking although small is a well designed craft and you can cough up quite a few fin combinations with all the fins they give you.
If it was me, i would suggest using 4 fins mounted swept forward... Adding more fins may cause it to weathercock...

 

[FastCargo]

I didn't take it to an extreme.

Didn't say you did, just using the example to make a point.

FC

 

[JPVegh]

3 fins, 4 fins, or 5 fins your super viking will fly fine. You got 2 kits why not 10 fins for a super super viking?:y:

 

[Bone Daddy]

Hey Greever

I forgot to mention that the reason I sim'ed my 2x Wizard was to see how it would affect max altitude. Turned out the affect was not much at all - less than 100'.

Don't mean to hijack your thread.

Bradycros

My BT-20 bird with an increasing number of identical fins looks like this in OpenRocket:

3 fins -0.8 cal
4 fins 0.5
5 fins 1.2
6 fins 1.75 as built
8 fins 2.29 OR maxes out here.

Captain Ron

I'm not sure if I understand how adding more fins of the same size would increase weather cocking.

I was more concerned that increasing the length too much would increase weather cocking.

 

[Greever]

3 fins, 4 fins, or 5 fins your super viking will fly fine. You got 2 kits why not 10 fins for a super super viking?:y:

Actually I was thinking 8 fins.......:horse:

 

[Greever]

Hey Greever

I forgot to mention that the reason I sim'ed my 2x Wizard was to see how it would affect max altitude. Turned out the affect was not much at all - less than 100'.

Don't mean to hijack your thread.

Bradycros

My BT-20 bird with an increasing number of identical fins looks like this in OpenRocket:

3 fins -0.8 cal
4 fins 0.5
5 fins 1.2
6 fins 1.75 as built
8 fins 2.29 OR maxes out here.

Captain Ron

I'm not sure if I understand how adding more fins of the same size would increase weather cocking.

I was more concerned that increasing the length too much would increase weather cocking.

No worries about thread hijacking. The more conversation the better.

I will have to find a copy of openrocket and learn how to use it, but in the meantime thanks again for doing the simwork for me.

 

[JPVegh]

I down loaded open rocket and was using it right away, it's easy.

I don't really care for rocket design software but I understand that a lot of people use it. I suppose if I ever designed something extreme I might use it but I really don't have a need for it with the kind of rockets I fly.

Anyhoo, have fun building your super viking it should be a cool project and would be a neat build thread.

 

[Greever]

I down loaded open rocket and was using it right away, it's easy.

I don't really care for rocket design software but I understand that a lot of people use it. I suppose if I ever designed something extreme I might use it but I really don't have a need for it with the kind of rockets I fly.

Anyhoo, have fun building your super viking it should be a cool project and would be a neat build thread.

I will download openrocket and play with it this weekend. Anyone know where to find it?

HobbyLobby had one Viking hanging on the rack. I had to get it even though I forgot to print a coupon this morning.

Time to dust off the camera and document the build. :horse:

 

[FastCargo]

I will download openrocket and play with it this weekend. Anyone know where to find it?

Easy peasy:

https://openrocket.sourceforge.net/

FC

 

[boggs]

Hey greever, have you ever been to commonwealth displays in southgate? They have a crazy amount of rocket kits for sale, And you can buy just a tube and make that wizard really............................long.

Jeff

 

[Rocket_Man]

the shape and size of the nose cone IMO is the biggest factor of drag. unless you have a unusual large size shape of fins op:

 

[Greever]

Easy peasy:

https://openrocket.sourceforge.net/

FC

Thank you. :handshake:

 

[Greever]

Hey greever, have you ever been to commonwealth displays in southgate? They have a crazy amount of rocket kits for sale, And you can buy just a tube and make that wizard really............................long.

Jeff

No I haven't. Is that somewhere here in Michigan? I just moved here from Phoenix, AZ. last November.

I have found a Hobby-Lobby, and the Ryders Hobby Shop on 28st.

I also found a group on the net that does launches outside of Muskegon so I thought I would make my BAR status official there. It's been 26 years or so since I have launched a rocket.

 

[boggs]

Commonwealth is in Southgate on dix-toledo. They are in the vendor section on here. They are only open on saturdays 12-8 or so. You are going to love it, it crazy how much stuff they have. I'll prob shoot up there tomarrow to pick up a kit they have on special.

 

[Greever]

Amazing that they are only open on Saturdays.

I will check it out though, but not tomorrow. Tomorrow is The Spring Thaw at Torresen Marine in Muskegon. Lotsa good deals on Sailing stuff, and free seminars, food, etc, etc.......

After surviving my first Michigan Winter I am ready for Spring!

 

[jFlds]

Greever, some of our folks make the trek up there to fly at times and some of the Muskegon folk make the trek down to our field as well.

You are always welcome to come down and fly with us outside of Three Oaks.

https://www.michianarocketry.org/

Plus Red Arrow Hobbies is local.


-jim

 

[Greever]

Thank you for the invitation Jim. I just may take you up on that. They are saying with this cold Winter we may not be launching our sailboats until late April.

 

[jFlds]

Next launch is supposed to be the 26th. keep an eye on the website and or our Facebook page to keep updated.

You can hit michianarocketry's channel on youtube for some clips of some of our launches.

Hope to see you at one soon!

 

[Greever]

Cool. I just may see you there. Especially if you are offering me a beer!

The "SuperViking" build is well underway. My intentions are to get further along before starting a buildthread.

Would the Low Power section be the appropriate place for that?