My first HPR build

[Salvage-1]

I see articles in the magazines about HPR builds, and peoples first addiction to the new area, so, I thought I would start my own thread on here to further introduce myself and what i am getting myself into.

So..
After doing a lot of looking around the net, brochures, YouTube vids of flights, etc. I came up with a plan to create a modular rocket that could be used with 38mm and 54mm motors, and would be possibly light enough to send skyward with 29mm in an adapter.
My choice was a Binder Design Excel Plus in 38mm, then when I have finished the main rocket, get another, a standard Excel in 54mm. The Excel Plus is basically the standard 4" Excel 3FNC with a dual deploy setup (payload bay and front body tube). Excel is 50" and the Plus is 71" so that gives you scale. Since both are available in 38" and 54" this means that with good planning and quality build, I will be able to use this in 4 possible configurations:
1 - Standard 50" Excel in 38mm
2 - Standard 50" Excel in 54mm
3 - Excel Plus in 38mm
4 - Excel Plus in 54mm
So, this would give me plenty of 'rockets' and room to play G through K. Some playing around with RockSim also told me that some high I's and a lot of K's may even boost this project to the 1m high and Mach 1 barriers, if the airframes last that long.

This is mostly going to be my sanity and build 'log', but feel free to chip in comments, I am positive that there are people on here with knowledge that I dont yet know that I need.
Also looking at flooding the thread with pics so show what I am up to.

Rob

[Aksrockets]

Good choice. The BD Excel is one sexy beast! Do you plan on doing any re-enforcements. I have considered a 'glassing a BD Excel but I scratch built instead.

Have fun and take lotsa pics!

Alex

[Salvage-1]

Here we go, a large ominous box from arrived. 4 days from order to delivery!!!

Taking it out and doing a parts check showed that everything was there. The quality of the fins and centering rings are excellent, no damage to any of the tubes, good to go for dry fit. The instructions from Binder are EXCELLENT! 6 pages of text and diagrams for the main rocket build, an extra sheet for motor retention and one more sheet for the construction of the AV bay.


Click for larger pic

Dry fitting took just about 30 mins from opening the box. This is a sturdy kit. Holes for TTW fins were already cut and just had to sand them a little to get better fin fit.

----

Next thing was to start work on the body tubes. I have a few cans of Sandable Sealer around the garage, so I just headed for that. I quickly found that it takes a few more passes with the spray and sand on this thing than it does with my Estes and Aerotechs, bigger tubes = deeper spirals. Anyhoo, started on this route, so i just keep on going. I realise that it may have been a lot faster to go with putty direct to the spirals, and I may do that on the next build.
5 coats and sands later, I am at the point where i NEED to do something else.

[Salvage-1]

On to the fin can.
BD uses through the wall attachment on this kit, which means lots of areas where you can beef this little beastie up. I tacked the fins and rings onto the motor mount tube with a some wood glue to whilst the can was inside the body tube, using the fin slots already cut and the template on the back of the instruction manual. Everything went perfectly. I also realised that at this point I had to think about the options for motor retention, so, instead of fixing the MMT flush with the ass end of the rocket, I had it stick out 3/8" so that i could put an AeroPak on there.

Note that this kit used two centering rings and one thrust ring. The thrust ring is epoxied onto the back centering ring and is wider so that it can glue to the rear of the airframe and so pushes direct.

When everything had set it was time to slice out the rear of the fin slots so that i could slide the assembly out and start the 'beefing up'

click for larger pic

I didnt bother putting any aerofoil on the fins, just rounded off the rear edge and put a blunted 'blade' on the front. The 3/8" plywood fins are nice quality.. they sand well without fraying and take sealant and sanding well.

[JPVegh]

Nice rocket, should be loads of fun.

[skyspike1]

I'm suprised your not digging around in your local 'Salvage Yard' for parts for your extremely large HPR manned spacecraft project!...

sorry,couldn't resist.....that show was one of the things that instilled the love of Rockets for me growing up!

[GDJ]

I thought you said you got the big rocket......

[Salvage-1]

I'm suprised your not digging around in your local 'Salvage Yard' for parts for your extremely large HPR manned spacecraft project!...

sorry,couldn't resist.....that show was one of the things that instilled the love of Rockets for me growing up!

Yup my handle really does show what bracket i am aged into. I loved the show too, and have been looking for it recently without joy. Looks like you can get the pilot on youtube though! It was ahead of its time, and so got axed after the first season (oooh.. sounds like Firefly!!)

[KurtH]

I did not see this thread before, we were building the excel at the same time!

I also built mine with a strato logger. I found 750 milligrams of 4f worked great for each charge. I used it for my l2, L1 should be pretty easy, I used an h242 for the first flight , it got to 933 feet. An I233 got to 1610 feet, and my L2 on J381 went 3082 feet.

This is a very versatile rocket. Good luck!

[Stewart]

I also am just finishing up my build of a Binder Excel plus DD, also useing a stratologger , just need to epoxy some shim stock onto the nosecone coupler and inside the upper body tube for the sheer pins, build thread here :- http://www.ausrocketry.com/forum/vie...php?f=6&t=3547

[Aksrockets]

Simply smashing. Superb. Most Excellent. Two thumbs up, 41/2 stars.

Right on, good man.

Alex

[Salvage-1]

Nice build Stewart.. is it true that Irish Rockets fly backwards, and Australian ones fly upside down? I hadn't even thought of the possibility of Hybridizing the Excel + So many things (for example the length of the bottom tube) make that workable. Hmm.. gives me an idea for the 54mm build.

So... went out today and did the static tests for deployment charges. I have added an Adept22 and wired it into the second set of charges. If you noticed from the above Alt Bay pics, there is the 1/2" pipe cap for use with a 1 1/2" length of PV Pipe (Epoxy plugged on bottom end) AND there is a 'christmas tree' bulb socket epoxied into its own hole. I had both of them feeding off the Euro Block, and the Stratologger would fire both (i also used a Xmas tree bulb in the PV block for igniter). Now I have them split with one going to the block and one to the bulb socket.

So.. yup, 0.8gr 4f works well on shoving the top half off (Main), then I went to test the bottom (Drogue) with 1.2gr.... hmm.. i think that i got a little more that i wanted in there. The bottom half shot off with a loud boom and surfed the lawn for a while before stopping 15ft away. The shock cord is 12ft long, and was still attached to the forward centering ring. The eyebolt remained intact but the ring ripped out.
On closer inspection, there is a ring of epoxy still on the inside walls of the body tube, and on the outside of the motor tube. The rings make a perfect shelf for the centering ring. No sign of epoxy on the front of the ring.
I was sure that I HAD done this, but, suppose a check first would have helped.
BEST thing about this is that it happened in my yard and not at 3500ft. I have already managed to get the ring back in and epoxied it to the 'shelf'. I have ordered a coupler that i am going to slide in front of the centering ring and glue that one in place. That then will provide support for the front edge. Then... lots of epoxy fillets.

This shows the problem with this design. No.. not any problem with materials, but a problem that i CANT get my arm all the way down to the ring to get some nice fillets. Its gonna be 'aim the drips'.

[Rex R]

ya know, 3/16" brass tubing will slide into the handle(tight fit) of most epoxy/acid brushes...and can be had in 12" or 36" lengths*....
rex
*with a bit of 1/4" brass one can probably go up to 6' or 7' long.

[Stewart]

Rob, thanks for the compliment
Re your centering ring fillets , tape a disposable shotglass onto a piece of dowel , use 30min epoxy with some milled carbon or glass mixed in , you should have no probs pokeing the shotglass to were the epoxy is needed.
Stewart
Oh the great thing with the longer motor mount is I can reach the eyebolt to atatch the shockcord

[Stewart]

Rob, a small sugestion, make sure you seal the wire exit holes in the avbay bulkplates espesially the droge end , the pressure of the droge charge may cause the main to fire.
also do the back of the christmas tree bulb socket as per perfectflites recomendation, hot glue or epoxy.
Stewart
PS the direction of flight downunder is just a matter of perspective or relativity