Der Ed Max Upscale

[kenstarr]

Does the world need another Red Max? Probably not. Does it need an Ed Max? It sure does!!!
Anyway, I always thought the Der Red Max was a dumb looking rocket with disproportionate cartoonish fins. Then one day maybe October or November 2021, I had a change of heart. Straight out of the blue, and I needed one. I started with a random piece of sonotube, low grade plywood, pink foam and started building a nose cone (the thread for that part is here:

https://www.rocketryforum.com/threads/hot-wire-foam-cutter.168908/
The process has been slow, I've got the majority of the rocket built however over the next few weeks I'll show off some of the steps and pictures that have happened thus far and hopefully it will be of interest to someone.
Ken

 

[kenstarr]

Here's continuation on the nose cone.

 

[DabCat]

Are you planning to glass your body tube? If so, what glass?

What thickness fins will you use?

What size mmt are you putting in it?

Strangely enough, I am currently in the works if building a red max nearly identical to yours. I'm also using the 4ftx8in quick tube with a foam nose cone. I'm planning to add an extra foot though as a stronger shoulder for the nose cone. I was planning to do the soller 7in sleeve on the body tube and nose cone. I will use 3/8 birch for my fins and centering rings and do 1 layer of tip to tip.

 

[kenstarr]

Are you planning to glass your body tube? If so, what glass?

What thickness fins will you use?

What size mmt are you putting in it?

Strangely enough, I am currently in the works if building a red max nearly identical to yours. I'm also using the 4ftx8in quick tube with a foam nose cone. I'm planning to add an extra foot though as a stronger shoulder for the nose cone. I was planning to do the soller 7in sleeve on the body tube and nose cone. I will use 3/8 birch for my fins and centering rings and do 1 layer of tip to tip.

Oh DabCat, just wait! I'll put pictures and discussion on the airframe later today. Yes there is soller sleeve!

 

[kenstarr]

So the nose cone is pretty much covered although I just got it primed this last Friday so let us delve into the airframe.
Obviously I had to have the sonotube before I did the nose cone. In selecting the that tube I pretty much picked out a size that looked favorable and wasn't too smashed in. I gave it two layers of Soller Composites sleeve

 

[DabCat]

So the nose cone is pretty much covered although I just got it primed this last Friday so let us delve into the airframe.
Obviously I had to have the sonotube before I did the nose cone. In selecting the that tube I pretty much picked out a size that looked favorable and wasn't too smashed in. I gave it two layers of Soller Composites sleeve

Is that the 7in sleeve? Also, thank you for posting this. This will help me immensely.

 

[kenstarr]

Yes the sleeve was 7". You can see in the first picture I used some wire to tie off the end so the sleeve would stay put at one end. In applying resin and fiberglass, it's more ideal to wet out the glass from underneath but that seemed way too difficult with such a large tube. I slathered on the epoxy and massaged it in and used a spreader to squeegee it and allowed gravity to help me with the particular "top down approach" if you will. After the application, I tied off the other end with wire nice and tight like than used electrical tape on the ends to make it nicer.

 

[kenstarr]

I just had a thought I realized I had failed to mention Somewhere in Time in the opening of this thread. Why a Der Ed Max instead of Der Red Max you wonder? Wonder no more! Mark down the road... Long way down the road at stickershock has some vinyl

Meet our friend Eddie! Looks something like this. I had him do some custom changes though as I like The Red and the Black scheme better

 

[kenstarr]

Alright, I have a minute finally this week. The fins need some show and tell. So I love drawing rough sketches on my yellow pads and in the early design phase this is what I came up with. A layer of foam board in the center, one layer of 4oz fiberglass on each side followed by some light weight luan panel and the whole assembly covered in 2 layers of S-glass. No idea of any engineering specs but they seem awfully rigid and lightweight, and they're good and chunky looking, perfect for a low and slow Max!

 

[kenstarr]

To get all the fin pieces cut out, I made a template from .125" MDF. Templates are time savers! Cool picture huh. Tomorrow I'll get some up of the laminating and profile

 

[kenstarr]

Here are some more pictures of the fins under construction. I used US composites laminating epoxy and some plastic squeegees to get the resin drawn up through the fiberglass. Once they were assembled I trimmed of the excess, sanded where necessary and ran a router around the leading and trailing edges.

 

[kenstarr]

I forgot to mention, after the edges were routed, I added more fiberglass around those leading and trailing edge areas.

 

[kenstarr]

Here is the fin and motor assembly, or powerplant if you wish. I decided upon a 75mm central motor with 3 29mm motors around it. Not that I would need them with an L in the middle but maybe if I used a 54mm K or something to that effect. I tell you what, getting the fins aligned was interesting. I made a couple of 120° templates to align them with radially and used some squares for perpendicularity. And yes, I even used hot glue... But only for a couple of tacks to hold them while the initial epoxy cured

 

[Theory]

Love everything about this!!!!

also have a soft spot for the “xxx max” rocket.

 

[kenstarr]

So with the power plant built, I found it necessary to plug the extra 29mm holes in the upper CR and add some recovery hardware. I got the airframe slotted for the fins and rolled the totally awesome Ed Max wrap from Stickershock. Mark was an absolute pleasure to work with! We wound up having a situation where the vinyl I received didn't match the dimensions I gave. I felt really bad mentioning it to him but he was so good about it and sent me a new piece of vinyl super fast. The rocket is looking awesome! I also got the external access avionics compartment installed!

 

[kenstarr]

I believe the knot is a beer knot. Don't quote me on the name. Learned it from the book On Rope. It's just an overhand knot for hollow webbing where one end is inserted within the other and a pre-tied knot is worked down to the middle of the "splice"

 

[kenstarr]

Other than mounting batteries and recovery, it's done! I'm super happy with the way its turned out.

 

[JRL303]

Fantastic. Really nice build!

 

[kenstarr]

Update! We flew the Ed Max on 5/21/22. Perfect flight! Loads of black smoke on the pad until the L390 came up to pressure (rail start?) I had redundant augmented ignitors in the main motor but it was still a bit slow coming on line. My boy has some video footage of the launch I'll get posted sometime this week.

 

[kenstarr]

View attachment IMG_4163.MOV

 

[kenstarr]

Well, my boy shot the video. Not sure what happened with his editing.
I suppose you get the idea. Black smoke, too long of a delay in starting the central motor. Rail start??? Still an awesome flight.

 

[SmurfTacoSupreme]

Very nice!

 

[Wayco]

Great flight Ken, glad we were there to witness it!

 

[DabCat]

Amazing build and great flight!

Quick few questions for you:

What did your final weight end up being (Without motors, but with recovery gear)?

I noticed the tubes have some sort of wax coating the inside (Presumably to help stop the concrete from sticking). Did you do anything to remove the wax? Or did your glue bond to it just fine?

How high did it get with the L390? (Your post says L390. Did you mean something else? I don't know of any L390. Did you mean L930?)

How is your deployment set up? Do you have a charge well on the top centering ring that is fired from altimeters in the side hatch? It looks like you are just pulling the main out at apogee and do not have a drogue. Correct? What parachute did you use (size and brand)?

 

[kenstarr]

Amazing build and great flight!

Quick few questions for you:

What did your final weight end up being (Without motors, but with recovery gear)?

I noticed the tubes have some sort of wax coating the inside (Presumably to help stop the concrete from sticking). Did you do anything to remove the wax? Or did your glue bond to it just fine?

How high did it get with the L390? (Your post says L390. Did you mean something else? I don't know of any L390. Did you mean L930?)

How is your deployment set up? Do you have a charge well on the top centering ring that is fired from altimeters in the side hatch? It looks like you are just pulling the main out at apogee and do not have a drogue. Correct? What parachute did you use (size and brand)?

Weight: I'll look it up for you when I get the chance.

Waxy coating inside the tube: I tried to peel it off or rough it up good where the centering rings were attached. Seemed like the epoxy bonded to it just fine but where there was bare cardboard, it seemed to soak in more.

I really said L390!!, good catch. It was a Loki L930. I'll check out the altimeter tonight. Boost wasn't terribly straight and it arced over pretty good. Motor was a wee bit under powered.

Deployment: no charge wells, just charges nested in the motor tube. I'll put a picture of the complete av bay up later. Too keep it simple, I ran the deployment wires out of the av bay, outside of the rocket then back in above the fore motor mount CR. No corrosive deployment smoke in this bay! Parachute was a Tac 3 xl size I believe. No drouge except for the small one to help deploy the main. I going to invest in a cable cutter though! It was super hard to find the rocket!

 

[kenstarr]

Went to pull up the apogee info from the Rrc3 and no data! I'm surprised I didn't write it on the rocket either when I found it. Here's the av bay

You can see how I routed the wires. Each altimeter had redundant ignitors. Glad I had redundant altimeters though because the eggtimer never armed. When I found the rocket it was still chirping ready to launch. I need to test it in the vacuum chamber as it's suspect on account of some soldering issues. I didn't have the chamber when I built the altimeter but I've since purchased one for vacuum degassing of various things.

Rocket weight was 20 lbs without the motors.

 

[waltr]

I do not see a vent hole in your AVbay. Possibly why the Quark did not 'see' the LDA and Arm.
I know there is leakage around the AVbay hatch but maybe this wasn't enough.

But the RRC3 did fire (good thing) so it saw the 300' LDA.
Am very interested in what the Vacuum test on the Quark shows.

 

[kenstarr]

The hole is in the guitar... Maybe needs another.

 

[waltr]

The hole is in the guitar... Maybe needs another.

Nicely hidden, I missed it.

 

[DabCat]

Weight: I'll look it up for you when I get the chance.

Waxy coating inside the tube: I tried to peel it off or rough it up good where the centering rings were attached. Seemed like the epoxy bonded to it just fine but where there was bare cardboard, it seemed to soak in more.

I really said L390!!, good catch. It was a Loki L930. I'll check out the altimeter tonight. Boost wasn't terribly straight and it arced over pretty good. Motor was a wee bit under powered.

Deployment: no charge wells, just charges nested in the motor tube. I'll put a picture of the complete av bay up later. Too keep it simple, I ran the deployment wires out of the av bay, outside of the rocket then back in above the fore motor mount CR. No corrosive deployment smoke in this bay! Parachute was a Tac 3 xl size I believe. No drouge except for the small one to help deploy the main. I going to invest in a cable cutter though! It was super hard to find the rocket!

Thanks a bunch. It's interesting that you found the L930 to be underpowered. About how high do you remember getting? 2k? 3k? Mine seems like it will be a bit heavier than yours. My fins will be a lot heavier. I was planning to run a L850 for the first flight, and the L850 is very simular to the L930. I'm going to build mine with a bunch of outboards, so maybe I'll just fill the outboards with blue thunder motors to give it a little extra kick off the pad.

How did you make the side hatch? Did you just use a Dremel after the fiberglass was done? Do you have your side hatch mounted to the motor tube or just the inside of the body tube? I'm planning to mount my altimeter sled to the central motor tube and run ignitor wires through the centering rings for airstarts. Ejection charge wires will just run through the top centering ring.