Six Second Delay - Really?

I am building a Terrier Sandhawk. View attachment ts1.rkt I put the design in RockSim and ran a simulation with an Aerotech reloadable D9. It says I should expect a 6 second delay from burnout to apogee. I don't have a lot of experience, but this strikes me as way to long for this rocket. It seems like RockSim has given me overly long coast times in the past.

Am I doing something wrong? Is it really safe to fly this rocket with a D9-7?

Any help would be appreciated.

RickW

Check the weight & CD that Rocksim is using. These are the biggest problems with altitude prediction. With most of my designs in RS they come up light & I have to add quite a bit of weight to get them even close.


JD

Built weights are going to vary from builder to builder. I tend to build alot heavier than the next guy, more glue, fillers, paint, heavier hardware etc. Base yor motor selection and delay times on the actual factual finished product.

JDcluster said:

Check the weight & CD that Rocksim is using. These are the biggest problems with altitude prediction. With most of my designs in RS they come up light & I have to add quite a bit of weight to get them even close.


JD

Click to expand...

I don't have a clue what a realistic CD would be. Under the Cd Override tab in Rocksim reports "Cd for the sustainer stage alone" as 0.75 -- whatever that means.

I'll check the weight as you suggest. I wanted to get a scale anyway.

Thanks for the help.