I'm in favor. I have been meaning to bring this up myself but I keep forgetting. But let's not make the mistake that Mach Madness is about to make by paying any attention to baro-based velocity estimates. From the data I've seen from my own recent transonic boosts, I'm afraid that's going to be a disaster, because above about 400-600 mph, the baro data is all over the place, with extreme sensitivity to nosecone configuration and vent hole placement.

Altitude records are great fun, but how about speed?

Any thoughts?

Mark

J570s at twenty paces 😀

I think it would be fun to do, but as Adrian says - a bit hard to quantify. Drag races are almost never lit at the same time and even if they were, max velocities are hard to compare if different motors hit stride at different points.

I don't know about Rocketwhiz, but what I had in mind was just a top speed record, a la Mach Madness at LDRS. Featherweight Altimeters is sponsoring a prize for that, by the way. Integrate data from an onboad acclerometer to see what the top speed was. Your K shot went 1178 mph, by the way, edging out Barack-it on the G80 with 1118 mph. How fast did your sim say that your M shot went?

A light rocket with a J570 would do great, but I think a J825 in that rocket would do even better. I have a crazy sim that has a J825 sending a rocket to Mach 3, well over 2000 mph.

I think I'd use barbecue paint on that bird....

W

I don't know about Rocketwhiz, but what I had in mind was just a top speed record, a la Mach Madness at LDRS. Featherweight Altimeters is sponsoring a prize for that, by the way. Integrate data from an onboad acclerometer to see what the top speed was. Your K shot went 1178 mph, by the way, edging out Barack-it on the G80 with 1118 mph. How fast did your sim say that your M shot went?

A light rocket with a J570 would do great, but I think a J825 in that rocket would do even better. I have a crazy sim that has a J825 sending a rocket to Mach 3, well over 2000 mph.

Top speed for each motor class. same format as altitude. It would have to be accelo-based. baro's are to flakey & gps can't handle the Gee's.

Luckily my wife just bought me a Parrot for my birthday. (Why yes she is the greatest, sorry her sister is married to) 😀

How fast did your sim say that your M shot went?

Adrian, as you know, Rocksim doesn't simulate VK cones very well. My best guess on velocity on that boost was between Mach 2.0 and 2.3. What little primer I had on the rocket was pretty much melted or removed. "Mach Rash", as someone said.

I plan to restore the rocket, but not to fly it again.

My J570 and I600 rockets sim to 1300-1400mph...

I think I'd use barbecue paint on that bird....

W

What temps are we talking about in this range of speed?
Fascinating read!

I think some of the damage I had was due to the motor's heat, which is no little thing on a minimum diameter rocket. There just isn't anywhere for the heat to go but right to the surface. That said, I've never had such damage on any previous boost, and I'd guess all but a couple of my last 40 boosts were minimum diameter. Something was clearly different this time.

I'd say 90% of my damage on the M was on the airframe between the fins, i.e. on the aft end. The motor, of course, extended far above that area. I don't know why similar issues were not seen underneat the motor above the fin area -- if it was indeed related to the motor's heat. Most of the rash was on the bottom 12" of the rocket.

The remaining 10% of my damage was on the very tips of the fins and near the bottom of my nosecone. I had some "weeping" of the primer at the base of the nosecone.

I'd be interested in this as a record option as well. I'm not going to be flying super large motors, so the more things I can do on small impulse the better.

Or, take it one step further and have records for acceleration. Assuming you squeeze an accelerometer into a mosquito-esque rocket, then the LPR birds are in the running.

But then there's recovery... 😉

Ken

I think I'd use barbecue paint on that bird....

What kind of temperature is the BBQ paint good for? I was thinking of just using cotronics epoxy and thin FG for the finish. No primer to run. I've checked out the contronics epoxy website, but they don't have any prices. Maybe one of those "if you have to ask you can't afford it" sort of things.

I've heard on the Composite Rocketry group that Cotronics is $80 for less than a 1/2 pint and that it has a maximum shelf life of 6 months - use it or lose it. I've been planning on buying some for a future project, but I'm going to wait until that project is in process before I do and I'd be happy to share it with others as I don't think I'll need the full amount to tip the leading edges of fins and fillets.

Depends on the BBQ paint. Engine paint can take 500 degrees supposedly and the black BBQ paint I used to recondition the BBQ exterior is rated to 1200 F, but I would doubt it. I don't think there is a glue in the world that could handle that temperature if it's made from organics of any kind.

W

I used stove paint for years on my drag car, it burns off over a short time at those temps...... There was a ceramic process for coating the headers and it stayed on. But, I don't remember how they did it and definitely wouldn't know if it was safe on fiberglass or Carbon Fiber. I could check with some of the old race shops and see if they still do it. Assuming they are still in business. There was another odd substance called plasmacerammic that was used to make piston rings in ultra high temp NOx "bottle" fed cars. Nitrous Oxide tends to melt down Chromolly and cast rings pretty quickly. Again, no idea on process or even correlation to this.

This may be a dumb question, but, has anyone used Kevlar in place of glass? What is it good to for temp? Plasticare sells it by the yard.

I used stove paint for years on my drag car, it burns off over a short time at those temps...... There was a ceramic process for coating the headers and it stayed on. But, I don't remember how they did it and definitely wouldn't know if it was safe on fiberglass or Carbon Fiber. I could check with some of the old race shops and see if they still do it. Assuming they are still in business. There was another odd substance called plasmacerammic that was used to make piston rings in ultra high temp NOx "bottle" fed cars. Nitrous Oxide tends to melt down Chromolly and cast rings pretty quickly. Again, no idea on process or even correlation to this.

This may be a dumb question, but, has anyone used Kevlar in place of glass? What is it good to for temp? Plasticare sells it by the yard.

BlackJack AK5000 Headers! A nice pair. Aluminized coating. Never could afford a set when I was a Kid.

I bought some of that Yellow Kevlar whan I was down there Monday.
I also bought some black Kevlar from Soller. I thought a layer in with CF
would be good at the fins and maybe at the tub ends to fight zippers.
Ed was telling me you cant sand it though. You get fuzzies. Perhaps a light layer of glass on top.

Scott e