Super Big Bertha----What a Pain To Build!!!

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ep29030

Mark N.
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When fins are large or multi-part, take the step of covering them with typing paper and then thin CA. Make them much stronger with small amount of weight. Because the Estes tubes are thin, Instead of all elastic, I use a length of kevlar until just outside the body tube, then attach the elastic there. Where the kevlar hits the body tube, I put several wraps of 1/2" wide tape to make a fat, round ball that will prevent zippering. If the centering rings concern you, just reinforce them -- Apogee has an article on strengthening cardboard rings. In most cases, making changes to increase your surface area for bonding can give you added strength without the weight of plywood and epoxy. I'm working on a LOC Warlock that will be built with foam core centering rings and a 54mm motor.
 

ep29030

Mark N.
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That's going the other route and using the CRs to transfer the load.
One or the other - or a balance of both
Yes, with TTW fins, the centering rings are usually just along for the ride. They need to be able to contain the ejection charge, but anything more is excess.
 

Mike Haberer

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Could have been stronger winds higher up, other than that hard to say without having seen it.
Agreed. The best way to get a sense of how the wind changes at different altitudes is to use the app Windy. It will give you data for wind speed and direction at several pre-defined altitudes based on weather data used for forecasting. It can be relatively calm at ground level and be 60 mph at 10,000 feet. The higher you go the more variability by level you'll experience. Once you get much above 5,000 feet where the bird is going to land is quite the crapshoot....
 

Sluggo

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So I guess once the thrust faded the upper winds easily came into effect and practically the whole coast was sideways. I use Windfinder but it only gives surface winds, I think. I'll search for Windy. Thanks guys.
 

SharkWhisperer

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In the US, surface winds and winds/temps aloft info at 3000 foot altitude intervals (to 12,000 feet MSL; then 6000 foot intervals to FL30...) is easily accessible on maps and tables from the NOAA Aviation Weather Center & FAA Flight Service websites, but aloft forecasts are only updated a few times/day and are provided as 6-, 12- and 24-hr forecasts. Winds aloft altitudes are MSL (above mean sea level) not AGL (above ground level) unless specified. Cloud ceiling reports (CLG in summaries) are always AGL. Pireps (pilot reports) are also publicly accessible and often indicate lower altitude wind/turbulence conditions experienced at the time of the report. They're online within 5 minutes of arrival and are deleted 2 hours after reporting. But it's unlikely you're going to get much rocketry-useful wind info from a Pirep beyond GPS-estimated winds and clear air turbulence, if any. https://aviationweather.gov and https://www.1800wxbrief.com (but don't bug Flight Service by phone unless you're flying HPR or an actual aircraft, or skydiving, and need a detailed preflight briefing--that might not be appreciated)...

Between surface and 3000 feet, watch the birds and the clouds (if any). If I'm skeptical, I'll sometimes launch one of my disposable "sounding Wizards" on a C motor to see where it pops and where the streamer drops it before tossing more valuable birds aloft.
 
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