Hi all... yes, I'm still alive, I have tried to steer well clear of this, and other rocketry forums recently due to various unresolved issues with certain parties that seem to crawl out from under their rocks every time I post publicly.
Firstly just to say thanks to Darren and Pete for letting me know about the ressurection of this thread
Ok, to answer a few questions.... firstly, I'm happy for anyone to make their own home made version of the Katana for their own use if they want. There aren't really any plans but I'm happy to provide photos etc. My only problem would come if anyone started trying to sell something like this as a kit or a plan-set without my involvement.
Yes, the original started out with a 38mm mmt, that was then replaced with a 54mm mmt and it was indeed flown on K550W, it has now gone back to the 38mm mmt and I've found that, if you can fit it in without pushing the nose off, the J570W is the best motor for this rocket... it makes children cry
I am still interested, long term, in a kit of the design but I persued the idea with several manufacturers to little avail back in 2002 - 2006 and to be honest, I don't really have the time these days to persue the idea actively as I have so many other commercial projects needing my time.
The issues with the rocket as an HPR kits are primarily that it would have to be a large single piece composite moulding for the main airframe... and there are very few kit manufacturers who have the experience and the facilities to make large glass/carbon moulded components. Your average HPR manufacturer (someone mentioned BSD as an example) assembles kits from outsourced components so would have to outlay a pretty big up-front investment to get something like this in production.
By way of example, I did start costing up manufacturing the rocket myself as a kit. I went to several UK based GRP moulding companies to look at the costs. In production runs of say 20 to 50 kits at a time (you'd be taking a massive risk to go for higher quantities) it was going to cost at least £1000 ($2000 US) up front for the moulds and then about £30 ($60) each for the finished components... and remember that's just the outer airframe. By the time you add in laser-cut centering rings, motor mount tube, parachute tube, recovery system, packaging, instruction leaflet printing etc you are getting up to around £60 ($120) cost to just put the kit together. Even if I just sell them directly to the consumer (cut out the retailers) I'd have to sell them for $180+, and then you'd have to add shipping... you'd be looking at $230 delivered for an 'I/J' powered HPR kit and tbh I doubt people would pay that... and I'd have to sell hundreds of them to make my investment back.
The only way it'll become viable is if the kit is taken on by an existing manufacturer (in the US) who has the facilities in house and is already set up to make fibreglass nose cones and put kits together. That way I think the thing becomes viable.
It works best on short squat motors with a high average thrust... so a 54mm mmt would be a good bet. I'm not sure how well it'd perform on the average short 75mm motor, it is somewhat sqirrely on any motor with a burn duration of 2 seconds or more.... but so long as the T/W ratio is high enough it should be fine.
It is an ideal design for small fields, you get a fast impressive lift off but a low apogee, on full 'I's it normally lands within 200ft of the launch pad even on a moderately breezy day.
Obviously smaller kits have a larger target market and lower initial set-up costs so are commercially more viable... but I'd think a 5" base dia version, about 30" long with a 38/29mm mmt (remember a short squat 38mm 'G' is far better to fit in there than a longer 29mm G) and a 8" dia, 48" long version with a 75mm/54mm mount in it would be the ideal two sizes to make. I'd think the former is do-able if manufactured in the US for an RRP of around $100 to $120 and the larger one around $160 to $200, or there abouts. I'd also be very interested in a modroc version. Heck, at 2" to 3" base dia it's almost viable as a plastic two part injection moulding.... maybe I should give Estes a call
The bottom line is this... I have stated before that, if a manufacturer is interested, I'm happy to license the design to them for a royalty on each kit sold. I'd be happy to provide designs, plans, and do the prototype work and testing to get it right, I'd also be happy to design and co-fund advertising in all of the rocketry magazines... I just don't really have the time to persue this and chase people and try and persuade them to go and do it.
So... if anyone REALLY is interested in this as a kit... go ask your favourite manufacturer to get in touch with me and we'll see what we can do.
my e-mail address for anyone interested is: ben (at) rocket-fx (dot) com
In the mean time... if I get time to do any HPR this year... I am gonna finally do a bigger version... with 13 x 38mm MMT's
Thanks all for your interest!!!
Ben
CCC Ltd
https://www.rocket-fx.com