6" Pegasus XL

[troj]

Herein begins a journey to build a 6" diameter Pegasus XL.

If you're not familiar with what a Pegasus XL is, here's an image of the real thing



This is going to be a slow-going project. I've actually been working on it for several months, and have gotten far enough to have accumulated a few key pieces.



This consists of two 6" x 48" pieces of MagnaFrame from Giant Leap, a 6" coupler, and a 1/4" thick Nomex honeycomb panel. The latter will be the core of the wing, as well as the rear fins.

I initially wanted to build an 8" version, but as I started collecting numbers, I realized that the win quickly becomes too large to be manageable, both in terms of transportation, and in terms of storage.

I spent about a month researching sources for the Nomex panel; I finally found someone who would sell me a 2 foot x 4 foot sheet for a bit shy of $100. Prior to that, I was finding about $100 just for the core, and I'd have to put the fiberglass on it, myself!

I'm still working on numbers; one of the harder parts is going to be drawing an accurate representation of the nosecone, which I can get to someone to turn for me.

The other puzzle is going to be deciding how to shape the wing. It's going to have the Nomex honeycomb panel as a core, and be covered with foam over that. I'll then put carbon fiber over that, to keep it all rigid. The challenge is in the shaping.

I'm also working on finding information on markings. I have a possible line on a set of RocketVision Pegasus decals. If I can lay my hands on that, I'll have a starting point.

The magic question of When is it going to fly? My hope is AirFest.

-Kevin

 

[MasonH]

This is getting a 75, right? It deserves it.

 

[Issus]

Looks like an awesome project. Why not make a CAD model of the nose and get it turned on a CNC lathe?

For your fins, its very easy to make a hotwire cutter if you don't have one already. You can make templates from MDF and hold them to the foam with bamboo skewers straight through the template as mini dowels. Alternatively, CAD and CNC router/mill I'd be happy to do them, but I'm guessing shipping from here will cost you more than paying a company in your own country to run them off. If you don't know anyone, try a local woodworking store and ask if they know anyone with a CNC router/engraver - they are starting to become quite popular in the woodworking groups and cabinetry. A hobbyist with one will set you back a lot less than a company and they are likely to put a whole lot more effort in.

 

[troj]

This is getting a 75, right? It deserves it.

I'm not sure, yet. I don't want to beat it too hard. I'll do a lot of building, and save the motor mount for one of the last things. Initial sims have been done with an L640DT, but weight estimates right now are very much a semi-educated guess.

-Kevin

 

[troj]

Looks like an awesome project. Why not make a CAD model of the nose and get it turned on a CNC lathe?

Cost, plus I don't have software (or skills) with 3D CAD. I have a friend who can turn nosecones for me, plus Gordy does great work, too.

For your fins, its very easy to make a hotwire cutter if you don't have one already. You can make templates from MDF and hold them to the foam with bamboo skewers straight through the template as mini dowels. Alternatively, CAD and CNC router/mill I'd be happy to do them, but I'm guessing shipping from here will cost you more than paying a company in your own country to run them off. If you don't know anyone, try a local woodworking store and ask if they know anyone with a CNC router/engraver - they are starting to become quite popular in the woodworking groups and cabinetry. A hobbyist with one will set you back a lot less than a company and they are likely to put a whole lot more effort in.

Hotwire is actually a challenge, due to the shape. We've used a hotwire a lot on our larger projects, but these are complex geometries. I have a friend with a CNC he's built, but he hasn't yet figured out how to do 3D. If he can get that working reliably, and I can figure out how to generate the files he needs, I'll go that route.

-Kevin

 

[cwbullet]

Subscribed and wow! The honeycomb is expensive.


Where did you buy it?

 

[CarVac]

What happened to the Talon?

 

[WillMarchant]

Cool project, Kevin! Do you want to skip the airfoil to try and lesson the tendency for this thing to "fly" off of a vertical trajectory?

 

[troj]

The honeycomb is expensive.


Where did you buy it?

I don't remember; I'd have to go dig through emails.

-Kevin

 

[troj]

What happened to the Talon?

Waiting on warmer weather, so I can take it outside and sand and fill and sand and fill and....

 

[troj]

Cool project, Kevin! Do you want to skip the airfoil to try and lesson the tendency for this thing to "fly" off of a vertical trajectory?

But then it's not a Pegasus! And that airfoil is going to give me fits in oh, so many ways!

What I really want is for Scaled Composites to make the wing for me.

-Kevin

 

[WillMarchant]

But then it's not a Pegasus! And that airfoil is going to give me fits in oh, so many ways!

What I really want is for Scaled Composites to make the wing for me.

-Kevin

You could probably buy the NuSTAR one as salvage... https://www.mvariety.com/regional-n...ned-as-booster-rocket-washed-up-on-island.php

 

[Issus]

Cost, plus I don't have software (or skills) with 3D CAD. I have a friend who can turn nosecones for me, plus Gordy does great work, too.

Let me know what you need Nose cones only take a few mins to do in SolidWorks and I can give you a PDF you can print/plot for a template

Hotwire is actually a challenge, due to the shape. We've used a hotwire a lot on our larger projects, but these are complex geometries. I have a friend with a CNC he's built, but he hasn't yet figured out how to do 3D. If he can get that working reliably, and I can figure out how to generate the files he needs, I'll go that route.

-Kevin

Guessing he's using Mach 3 for his controller? I use Cut3D, MeshCAM (not very good at two sided... doesnt like them up lol), or SolidCam depending on the job. CamBam will do it easily too. Just import your STL setup the toolpath and you're away Milling foam cores is super fast, use a ball nose bit and with close enough passes you can use the core directly without any sanding.

 

[cwbullet]

The core is now about 125-155 for that size.

 

[Pantherjon]

I'm not sure, yet. I don't want to beat it too hard. I'll do a lot of building, and save the motor mount for one of the last things. Initial sims have been done with an L640DT, but weight estimates right now are very much a semi-educated guess.

-Kevin

i would probably put a 98 mount in it..Can always adapt down..You may get a 'wild hair' and want to fly it on something BIG!:wink:

 

[CarVac]

Are you going to put I49's on the fin tips?

 

[CCotner]

Are you going to put I49's on the fin tips?

The story is that Warp9 propellant was originally developed for solid-rocket-motor reaction control systems (pivot-mounted super-long-burn SRB's) on the wing tips of Pegasus, with industrial solid propulsion (aerotech parent company) developing the motors on contract for Orbital. It would be fitting to put W9 endburners on the fin tips. =p

 

[troj]

i would probably put a 98 mount in it..Can always adapt down..You may get a 'wild hair' and want to fly it on something BIG!

Nope. Nose weight is required, even for 54mm. The heavier the motor, the more nose weight that would be required.

Plus, this isn't exactly a design that lends itself to Maximum Thrust, so going to a 98 just increases the odds of a shred.

-Kevin

 

[Viperfixr]

But then it's not a Pegasus! And that airfoil is going to give me fits in oh, so many ways!

What I really want is for Scaled Composites to make the wing for me.

-Kevin

If there will be an airfoil, I would go for a zero-lift wing as much as possible to prevent flight path deviation as speed/lift increases. I am not even sure a symetrical airfoil shape will do it, but I would think it is a starting point. I'd be tempted to experiment with small "spoiler" like devices on the top of the wing to make sure it is not generating lift. Bobkrech?

AWESOME project, btw. I guess after finishing that shower you had to have a new project? I'd go for that 75mm MMT just so you could go for the long-burn motors in that range and still have enough thrusties to get off the pad well. Can always adapt down to 54mm for that L640DT.

 

[troj]

If there will be an airfoil, I would go for a zero-lift wing as much as possible to prevent flight path deviation as speed/lift increases. I am not even sure a symetrical airfoil shape will do it, but I would think it is a starting point. I'd be tempted to experiment with small "spoiler" like devices on the top of the wing to make sure it is not generating lift.

Any deviation from the actual wing shape will quickly become evident; I'm going to try to stay as close to it as possible. I've got some info on what RocketVision did (William Maness has been very helpful!), and will go that route. Yep, there's risk to the flight with going that route; that's why this will fly farther out, and lined up such that if the wing causes problems, it will arc away from the crowd.

AWESOME project, btw. I guess after finishing that shower you had to have a new project?

Thanks. The bathroom isn't done...not even close. Most of the work, right now, gets done on the weekends. I've been slowly working on the Pegasus for at least six months, now.

I'd go for that 75mm MMT just so you could go for the long-burn motors in that range and still have enough thrusties to get off the pad well. Can always adapt down to 54mm for that L640DT.

I'll be honest, I'm not as interested in going 10,000 feet with this as I am in having it fly properly. That's why I'm not overly inclined to go with larger motors. Plus, the bigger motor, the more I have to add nose weight, to keep it stable. If I ballast for 75mm, then it may become too heavy for 54mm. I'm also not overly interested in a high peak velocity.

-Kevin

 

[troj]

Here is my saving grace on this project....

 

[BBrown]

The magic question of When is it going to fly? My hope is AirFest.

-Kevin

Have you talked to the launch organizers about you flying it at their field?

 

[troj]

Have you talked to the launch organizers about you flying it at their field?

Not yet, but I will.

-Kevin

 

[stantonjtroy]

Here're a few images I've collected for my project plus a few pics I took at Udvar-Hazey. Hope it helps for the markings.

 

[stantonjtroy]

A couple more. I have a PDF of the Pegasus Users Guide. In it there are some great cross sections of the nose area. Too big to upload but I can Email it if you would like it.

 

[troj]

When it comes to decals, like with a Delta, you have to decide which flight you're duplicating -- they're all different.

Right now, I'm working on all the dimensions. It's laborious.

-Kevin

 

[JordanT]

This is a cool project! I love the delta wing rockets, and Pegasus is probably my favorite. I have a 2.6"(?) version with a 29mm mount. It's first flight was less than successful, and it took so long to get to that point I haven't gone back to try and fix it.

 

[stantonjtroy]

I suspect, like the BOMARC, a great deal of nose weight will be required to get it to fly like a rocket and not an airplane.

This is a cool project! I love the delta wing rockets, and Pegasus is probably my favorite. I have a 2.6"(?) version with a 29mm mount. It's first flight was less than successful, and it took so long to get to that point I haven't gone back to try and fix it.

 

[rocketgeek101]

Here're a few images I've collected for my project plus a few pics I took at Udvar-Hazey. Hope it helps for the markings.

You know in the second pic, those metal bands could be simulated using large hose clamps. Just a thought.

 

[stantonjtroy]

If the scale were right, that would be awsome. Especially with the tensioning screw dressed up as a Marmon clamp. My project is at a smaller scale so I'm planning on using a 1/8" wide strip of aluminum HVAC tape.

@ Kevin; keep us informed as to your technique for building up the wing cross section. I'm still trying to hammer out a strong yet light structure for the wing.

You know in the second pic, those metal bands could be simulated using large hose clamps. Just a thought.