Deep Purple by Misha Rocketry Build Thread

So here we go. Arrived last Thursday, but due to work this is the first occasion I have had time to look at it.

I should say many thanks to DJ from Misha Rocketry for dispatching it so fast.

Unboxing



Out of the box, looking good, there a few imperfections in the carbon tubes (low points) and a few minor scratches but nothing major. You have to look carefully to spot them and when it's clear coated they'll disappear.

The fins are 4 mm thick. They are not beveled, so that's something I'll need to do. The centering rings are a whopping 5.5 mm thick





Tried a dry fit, but the fins were too tight due to the rounded ends of the fin slots

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No problem, a little bit of filing later and they are squared off



The inside of the tube where the fin slots are will need a little sanding too as the motor centering rings are a little tight where the slots are, making it hard (no impossible) to slide them past the slots.

I will get on with the sanding, and hopefully post a dry fit picture later today.

A preliminary dry fit

op:

Slots in the centering rings for fin alignment, This is good news as I'll be able to attach all fins simultaneously, but will need to get rings 100% aligned before epoxying them.



Pre-drilled holes for the av bay



This is a tube coupler, what a crime to hide it away.
Actually it's a lot oversize, probably about 4 inches too long and will obstruct the av bay, I'm wondering if it is supposed to be exposed a little as the rocket is coming in at 67 inches, and in the review thread JD reckons it's supposed to be 77 inches. There is definitely only 67 inches of airframe, nosecone etc. Hopefully DJ will respond to this thread with some advice. If not I'll cut it down to size with a tile saw

This should be appropriate for the build...

Smoke on the Water (Fire in the Sky)
[video=youtube;7mCK05dgwgU]https://www.youtube.com/watch?v=7mCK05dgwgU[/video]

There certainly isn't everything you need to complete the rocket in the kit.
So what else is required?

1. Shock Cords
2. Attachments for shock cords
3. Could do with a bulkhead to put in the nose for shock cord attachment

I would kind of expect items 2 and 3 to be there

No matter, I have some sheet CF that I can cut a bulkhead for the nosecone from, and an assortment of u bolts and o rings I can use.
I also have a lot of shock cord as I tend to transfer it between rockets, so don't necessarily use it when I get in a kit. Same with parachutes.
I think I'm probably going to do kevlar for the length of the body tube plus about a foot, then a link to 10-15 feet of tubular nylon.

I'll also be putting 2 raven altimeters in the av bay. This is actually a little awkward as the av bay is carbon fiber which conducts electricity which I found out before when I made my own cf sled, it warmed up nicely when the current went through it as the raven is actually live at the attachment points. So nylon screws are required which I now have a large stock of.

Simon said:

I would kind of expect items 2 and 3 to be there

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I would have thought so too for the price of the kit.

Subscribed

Subscribed!!

Getting ready to cut the missing bulkhead, as you can see by the CF sheet, I have done this before

Subscribed!
op:op:op:

Of course the drill ran out of power after 2 seconds, so its now on charge, in the meantime here are the ingredients for the epoxy I will be using.
Haven't got the exact formula yet, but I will post it when I've worked it out.
Any thoughts on these ingredients? Would welcome feedback.

Missing bulkhead cut. This is actually 50/50 Carbon Fiber and fiberglass, so its CF front and fiberglass back, but that's OK because when it's epoxied in, you'll never see the back.



I'm starting to get itchy, should've worn those latex gloves.

It's obvious that Cf was used for all the wrong reasons on this rocket.
Carbon Fiber is meant to: save on weight and for it's strength.
To use on anything less than minimum diameter rockets; should be considered a crime.


JD

JDcluster said:

It's obvious that Cf was used for all the wrong reasons on this rocket.
Carbon Fiber is meant to: save on weight and for it's strength.
To use on anything less than minimum diameter rockets; should be considered a crime.


JD

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What if you have huge fins and need stiffness? Even if the rocket is not MD is it still a crime?

JDcluster said:

It's obvious that Cf was used for all the wrong reasons on this rocket.
Carbon Fiber is meant to: save on weight and for it's strength.
To use on anything less than minimum diameter rockets; should be considered a crime.


JD

Click to expand...

Hi JD,
Everyone is entitled to their opinion, and I respect yours, in fact I there are probably a lot of people who will agree with you. I have made 4 MD CF rockets and unfortunately for me, I tend to lose them as I can't resist putting the largest motor I can possibly get in them and watch them disappear for good. I don't intend to do that with this one, besides my wife has already warned me against doing it again . But most importantly I simply like the look of CF rockets. I will be continuing with my criminal activity tomorrow, probably beveling the fins.

Simon said:

Hi JD,
I have made 4 MD CF rockets and unfortunately for me, I tend to lose them as I can't resist putting the largest motor I can possibly get in them and watch them disappear for good. I don't intend to do that with this one, besides my wife has already warned me against doing it again .

Click to expand...

Why not use RF and/or GPS as trackers?

They make carbon fiber sticker material.

LOL I've always wanted to try one of those!!

g zilla said:

They make carbon fiber sticker material.

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Space Truckin might be more appropriate

K'Tesh said:

This should be appropriate for the build...

Smoke on the Water (Fire in the Sky)
[video=youtube;7mCK05dgwgU]https://www.youtube.com/watch?v=7mCK05dgwgU[/video]

Click to expand...

A5tr0 An0n said:

Why not use RF and/or GPS as trackers?

Click to expand...

I do have a couple of AED GPS units but GPS doesn't work so well in CF rockets, due to the fact it can't see out. There is an alternative and that is to put in a fiberglass section or use a fiberglass nosecone.
I have been looking at using an RF beacon, but they are more expensive than GPS here.

Simon said:

I do have a couple of AED GPS units but GPS doesn't work so well in CF rockets, due to the fact it can't see out. There is an alternative and that is to put in a fiberglass section or use a fiberglass nosecone.
I have been looking at using an RF beacon, but they are more expensive than GPS here.

Click to expand...

Hmm.. what RF units are you looking at? The cheapest GPS unit that I have is $300 (USD).

Yes you would have to switch the NC and/or coupler to a radio transparent material. I am not sure how you design MD rockets but you could only switch out the coupler and bulkheads that houses the GPS/RF unit to fiberglass (or whatever) to solve that problem. Once the vehicle separates for apogee and main the coupler would be partially then fully exposed.

Anyways good luck with the build.

Hi Simon,
My apologies for the delayed response. Clearly we sent you one wrong coupler, just cut it down by two inches and you will be good to go. regarding the front (Nosecone Bulkhead) we do not include that as some rocketeers prefer to embed an eye bolt into epoxy (along with lead weights) when they are balancing their rocket. Bulkheads work as well, nice work.
I emailed you detailed instructions with annotated pictures, I hope you received them as they detail the assembly process.
For the 77" vs 67" My apologies, that is a typo which I will correct immediately.
On the comments of CF for this rocket versus Min Dia builds...We have a 54mm MD in the works we call it Blue Maxx...but it is not finished yet. We feel Deep Purple is a good design and worthy of its 6K Twill CF structure.
At Misha Rocketry we focus on the core components. Kevlar shock cords, Parachutes, eye bolts, etc are very much commodity products. Most rocketeers can buy these as cheap or cheaper than we can, there is not much value add that Misha can provide so we do not include these in our kits. In Simon's particular case, we shipped him the rocket free of charge via Fedex international priority. We wanted to get Deep Purple into the hands of an experienced rocketeer and get honest feedback. I am happy to see this posted as a build in this forum.

Hi DJ,
Thanks for the clarification. Unfortunately your email went into my junk mail for some reason. I am trying to give an honest opinion in the thread which I think is good for everyone. I was delighted by the speed of the free shipping, this is the fastest delivery I have ever had from the US by a long way.

I hope to finish the build this weekend. (one of the reasons for using CF, hardly any finishing required).
Launch date pencilled in for 16th November (weather permitting), if it launches there will be a video for sure.

Simon

Hi Simon,
Where do you Launch? Please do post the video.
Do you use Rocksim? I can send you the design file so you can simulate your launches/motors.
If not, tell me which motor you will be using and I will send you the results of the Sims.

Regarding feedback, please do post any and all. It will only help my son and I get better.
Also any feedback specific to the design and the build process will help us on our upcoming designs.
DJ

Please send the rocksim file, that would be very helpful, hoping to launch next Sunday.
Anyway, on with the build

I tried sanding the fins by hand, just didn't work so I went for the power tools, sanded at approx 30 degrees with the belt sander.

Here is the AV bay with the fins tacked on

Forgot to mentopn, I had to sand the inside of the AV bay housing to get it to fit

Here is the tool I used, everyone needs one of these



AV bay inserted

From there I started on the motor mount, it's a bit tricky because I had to make sure that the fin alignment slots where aligned properly



I really hope my guestimates are right, otherwise it won't line up with the pre-cut fin slots properly and I'll have wasted 700 bucks.
Just waiting for the JB Weld to go off overnight, then I'll find out whether or not I got it right tomorrow morning. Guess it's gonna be a sleepless night.

Simon said:

From there I started on the motor mount, it's a bit tricky because I had to make sure that the fin alignment slots where aligned properly

View attachment 245966

I really hope my guestimates are right, otherwise it won't line up with the pre-cut fin slots properly and I'll have wasted 700 bucks.
Just waiting for the JB Weld to go off overnight, then I'll find out whether or not I got it right tomorrow morning. Guess it's gonna be a sleepless night.

Click to expand...

Even if it is out of line you could cut part of the fin tab off so it doesn't come into contact with the centering rings. Of course it's not something you would want to do but more of a last case resort.