Activity

Batman, back to some of your original questions…. Here’s my thought. Laying a bit of glass on the airframe does many things. To wit, fiberglassing:- Fills the spirals, which is critical- Gives you a wonderful surface to wet sand to…   Read more»

All I can say is I’ve never shredded a rocket I’ve built for Mach+ flights…. EVER. My first Cirrus handled an I600, a J350 and a J285 and never shredded. My second remains to be seen, but it too has…   Read more»

Well, that should work, but approaching mach, there are several other things to take into account, including pressure waves and such. No idea how to calculate those.

I have to disagree with you on this one. I think unglassed, unmodified phenolic should be perfectly capable of taking a 38mm J motor in a minimum diameter rocket. The pressures and forces in play here are not massive, and…   Read more»

I’ve built 2 Cirrus Darts. The phenolic kit intends that you use one layer of tip to tip across the fins and comes with precut 6oz glass for that purpose. If you’re planning on flying and H or I motor…   Read more»

I have to disagree with you on this one. I think unglassed, unmodified phenolic should be perfectly capable of taking a 38mm J motor in a minimum diameter rocket. The pressures and forces in play here are not massive, and…   Read more»

I’ve built 2 Cirrus Darts. The phenolic kit intends that you use one layer of tip to tip across the fins and comes with precut 6oz glass for that purpose. If you’re planning on flying and H or I motor…   Read more»

Yeah – I used 4 layers of 4.8oz CF for my fins last year, and ended up with something that was about a third the weight and half the thickness of PML 1/16″ G10, but at least as stiff if…   Read more»

Batman,Thats would I did for my G80 SSS–2 layers of kev on the inside for shear resistance and 2 layers of CF on the outside. I need new batteries for my digital calipers–best guess is about 0.05″ thick and puts…   Read more»

As John said, you have to look around for the best price on the carbon. CST has great selection, but you pay a premium for it. ACP isn’t much cheaper. Aircraft spruce is OK, as John mentioned. One thing I…   Read more»

Batman,I’m thinking 0.4 min Cd is a good figure, but as you likely know this will vary with velocity, esp in the transsonic region, so I would not override the one calculated–or you will get way unrealistic results. But you…   Read more»

Chris – I plan to be at every launch and I would very much like to see your Cirrus. Hopefully we don’t get snowed out in Feb.For simulation purposes, what is a reasonable Cd to use for this type of…   Read more»

Chris,You are more than welcome to borrow my tracker when you need it (assuming in not needing it in that 2hour window when I actually get to fly).Batman, the Cirrus Dart is a great place to start for the J350…   Read more»

I have to say, a PML cirrus is a great choice, and should easily get into the 11k range on a J350. It won’t be a winning design, but it will give a good feeling for what an altitude bird…   Read more»

The AF doesn’t need any glass. Its good to have, but IMO the primary reason for glassing small AF’s for barely mach flights is the superior finish one can generally get. Also if you roll your own, it can be…   Read more»

well since this is my event i better get my rocket ready…. i will not have enough time to get it going for MHM but I would love to see some competition of some sort to do this!rules:1. 1 try2….   Read more»

Off the top of my head w/o a calculator–a hexagonal array of outboard h999’s around a central longer tube, each producing approx 200#’s for a thrust total of 1400#. I believe even with the cases and motors the weight could…   Read more»

Sorry, but 300 was the claim. Y know me. Produce a rock sim that shows 300G’s I’ll buy it.–provided its accelaration and not dee :PAnd a bit of a vent, I go point on this mission and there is no…   Read more»

ignore

Sorry, but 300 was the claim. Y know me. Produce a rock sim that shows 300G’s I’ll buy it.–provided its accelaration and not dee :PAnd a bit of a vent, I go point on this mission and there is no…   Read more»