2.56" Black Diamond

[Johnnie]

When my camcorder comes in, I will better better pics from then on, but until then bare with me and have a look at Black Diamond "Dressed to Kill"

With noe recovery, Black Diamond sits at 2 pounds 14 ounces...

 

[nialloswald]

Nice looking rocket! I'll be interesting in hearing how it flies since I'm working (slowly due to me and my rockets being in something of a long-distance relationship ATM!) on a couple of things fairly similar.

I've posted details on TRF before, but basically one is 2.6" dia, with a 'short' 38mm booster to take a WCH H100 (or up to a J350/Pro38 6-grain) and a 'long' 54mm booster for my ProPoly motors (which are itching to burn!) and potentially HyperTek stuff. I'm looking at (i.e. simming, so knock a bit off!)~2kft on the H, more like 9-9.5kft on the K350

The other started life as a Vb Bob acquired for a few pounds and a pint of carling (horrible, cheap english 'lager'!) from the clutches of someone who wanted to launch it at his landlord! The whole lower section is motor mount, 38mm, and will take up to a 36" motor. The plan is to fly it on the H100 to about 3kft, and later upgrade to the WCH J190, which like the SRS motor is a 36" monster.

1.3kg is impressively light! I saw an HT J250 in a ~2kg rocket this weekend, that really shifted (18G's off the pad!)
Of course there's no reason the 36" 38mm motor can't be used in the 54mm rocket, for a less extreme ride.

I will be interested to see how your rocket does on the SRS J motor - its a bit lower in total impulse than the WCH motor but not by a huge amount. Make sure you get photos/video, there's nowhere near enough of hybrids at the moment!

 

[Johnnie]

Make sure you get photos/video, there's nowhere near enough of hybrids at the moment!

I'll second that, more hybrid discussion is needed.

I have followed along with your BoB project, it should prove to be a sweet flight. I have a prebuilt BoB that I will add an E-bay to the middle of, and then I will fly it to some nice altitudes on the new SRS H78 (29mm)

The plan is to fly it on the H100 to about 3kft, and later upgrade to the WCH J190, which like the SRS motor is a 36" monster.

Here is a shot of the motor from rear of the Black Diamond.

 

[Johnnie]

The Black Diamond was designed specifically to fly this long motor. With that in mind, with the supplied eyebolt, the 36"{ long motor became a recovery device, and allowed me to make the booster somewhat "zipperless"

In this photo, the eyebolt comes to the middle of the booster coupler.

 

[Johnnie]

For a comparison, here is the booster, which is a full SRS J144 motor length.

 

[nialloswald]

They do look very nice, the SRS motors! Only issue with them for UK fliers is the ignition method, but I see no good reason why WCH/ProPoly GOx ignition wouldn't work.

Just about the only video I can find of a 38mm J hybrid (I think there may be some on the SRS website...) is Mike Harris' Periwinkles Pride, I think it was seeing how that thing (again 2.6") shifted (to about 4k6) that made me want to get into these motors.

I was originally thinking BoB might be good for RATT motors, but since I've gone down the WCH route, I guess it'll just have to fly on those I have however ditched the BoB's stock fins for some clipped delta ones, the stock ones are a bit gawky if you ask me!

The 'Sub-RATT' (good move I think) 29mm SRS motors look very nice, nicely priced too. I bet they'd go nicely in a minimum diameter rocket too

BTW, I think the dusky purple of the WCH motors is far more manly than those poncy blue SRS motors

 

[nialloswald]

You might have seen it, but:

https://www.bits.bris.ac.uk/niall/gallery/bob/IMG_1385

Is my booster collection - BoB, L1, L2. Fins have been made for BoB and the L2 booster.

How are you doing the venting for your SRS motor? I ummed and ah'd about how to do it on the 54mm booster, in the end I extended the 36" tube by a coupler's length (i.e. installed a coupler, installed another length of tubing, then the 'zipperless' coupler), leaving plenty of space to run the vent tube out the airframe. I figure I'll get a long length of vent hose, (say 10ft) and run it in from the top, through the MMT, and then couple it to the motor and carefully install the motor whilst pulling the spare vent line out throught the hole.

The SRS motor vent comes out perpendicar to the airframe a la HyperTek IIRC, must be a bit less fiddly.

 

[Johnnie]

BTW, I think the dusky purple of the WCH motors is far more manly than those poncy blue SRS motors


Purple is my color!!

I will post a progress flight report a week from now, as the Black Diamond will "rip the sky" next weekend...weather being all it can be.

 

[BrnAgainRoc]

hey johnnie,

i would hope you would make that maiden flight at our field in ringgold. We always have quite a few cameras there filming to get multi angle shots plus digi cams to get 16x pics leaving the pad.But id love to see that thing fly man.On rocksim what is the guesstimate on alt?

 

[Johnnie]

I would love to fly Black Diamond at your new field, and I am sure I will. But ST2005 is happening this weekend, and with everything that is going on, I have had to narrow my launches down to two...My L3 attempt on Saturday, and Black Diamond on Sunday.

4,700ft is what Rocsim 4 says Black Diamond will hit, I have not simmed it on Rocsim 8, as I am waiting for my copy to arrive...

 

[BrnAgainRoc]

no prob bro we wish ya alot of luck on ya maiden launches. Cant wait to have ya on our field and cant wait to fly with ya just as much!! Good luck on ya Cert 3 bro!

 

[Johnnie]

I was sure I updated this thread in Sept 2005 when I launched my 2.56" Black Diamond on the SRS J144...

The Short: The eyebolt unscrewed from the motor after deployment, only to lose the booster and motor

That was the last time that I have flown a rocket...

Now I will reserve the remainder of this thread for a new idea, and that is to make my new 54mm VB Extreme the replacement Black Diamond! I have been researching some Carbon Fiber sleeving for this kit, and I believe I have found a good combo.

So here is my marker, and a rocsim of the stock kit. As I work on what I hope will be my final design, I will update. I will say, that I hope to be able to utilize the stock parts, with a few Hi-performance mods, and loft this rocket on one of the new SRS 29 5/8" long J337 (3 second burn) or the J261 (5 second burn). 54mm motors, what else. This rocket could bust some nice altitudes...I would first like to see 1-mile again, then 2-miles.

Johnnie

 

[Chicagonative17]

Put it to 18,000 ft. on an AT K250! Don't forget the camera!

 

[Johnnie]

Put it to 18,000 ft. on an AT K250! Don't forget the camera!

I am actually considering the SRS K257 or the K347...6.1 and 3.6 second burns respectfully.

Johnnie