ColumbiaNX01
Red blooded white American male
Yes I am sure they are great products. But for a person like myself who has only dealt with Perfect Flight for the past 8 years was shocked at the prices of the altus metrum and their products
Staging Timers for 2 stage rocket
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Yes I am sure they are great products. But for a person like myself who has only dealt with Perfect Flight for the past 8 years was shocked at the prices of the altus metrum and their products
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Can't drink Champagne on a beer budget.....
ColumbiaNX01
Red blooded white American male
I am leaning towards the Featherweight Raven. My club members use those. They said with that altimeter can fire an igniter on the 3rd channel. If I go that route all I would need is 2 ravens. One to fire igniter and deployments and the 2nd one for backup of deployments. Still more research is need.
I would totally agree, don't buy any product until you compare and make sure it is designed to perform to your requirements.
To my point though, I would think the entire project is a little too ambitious, and poses a safety risk in and of itself if this is your first attempt at staging.
While legally there are no additional requirements for this flight profile beyond being certified L3, I think it would prudent to attain some experience and skill at staging on a smaller platform before attempting an M to L. Like Fred said, lighting an L up there carries a lot of risk, not that lighting an H up there couldn't go wrong either but the scale range of catastrophe is somewhat lowered. it would be the same advice I would give for a cluster flight, don't go out and try to light 3 M's on your first cluster attempt, get some experience on some smaller stuff first.
ColumbiaNX01
Red blooded white American male
I understand. But reality is if your using commercial motors, a rocket kit that was designed for strictly for 2 stage(not a modified single stage), Have all the required safety measures for staging. You have done all the proper simulations using rocksim and/or Rasaero. You know your CP for the whole stack and CP for the sustainer. Have the correct calibers of stability. Having it pre-approved from the leaders of the launch. What we do in rocketry is plan for the unthinkable. Using the proper electronics for staging that have the built in safety precautions for in the event it becomes land shark or endangers spectators. With all that said the risk is the same for as a H to I or a M to L. The same risks are there. But by using larger motors the risk is elevated.
Yeah, if it's any solace the Tilt-o-meter died for the fact that an essential part went out of production. I bet someone else will come up with something. Kurt
Sensing tilt isn't that difficult, though you do need parts that can withstand the high-G environment in the rocket. Another option I think I would use regardless is an R/C based failsafe. So I could hold the switch until the sustainer ignites, if I let go, no sustainer fires and the altimeters handle recovery. Even with good electronics, you might see a reason to scrub the staging that the gear can miss.
On a big project like the one in the OP, I think I would also set up an R/C backup deployment charge on a separate battery. If it looks like the altimeter isn't going to fire, I would like to have a secondary method available.
On a big project like the one in the OP, I think I would also set up an R/C backup deployment charge on a separate battery. If it looks like the altimeter isn't going to fire, I would like to have a secondary method available.
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I keep hoping that we'll get an Eggtilt-o-meter or Egg-IMU kit.
Salvage-1
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Let's look at it a different way. You are wanting to stage M to L. That is a chunk o change right there in just the motors. Hardware, tubes, etc for rockets. Man Hours put in to effort.
now... how much is the line for too expensive for the electronics / brains? Plus you are going to need some tracking. TeleMega shouldn't seem that expensive now, especially since it will be used in more projects than just this.
For a bonus, with the TeleBT unit, you can stream live telemetry through your phone or tablet. Hook this up to the clubs sound system and you have spoken live telemetry reports.
now... how much is the line for too expensive for the electronics / brains? Plus you are going to need some tracking. TeleMega shouldn't seem that expensive now, especially since it will be used in more projects than just this.
For a bonus, with the TeleBT unit, you can stream live telemetry through your phone or tablet. Hook this up to the clubs sound system and you have spoken live telemetry reports.
Agree and disagree, i still believe an M to an L adds some additional risks that aren't there with a smaller platform. Out of curiosity, which kit are we talking about here? I wasn't aware that there was a kit made strictly for two staging that would fit this profile.
Don't believe the Wildman 3 or any other 2 stage KIT that I'm aware of would support an M to L flight profile without modifications. Wildman 3 with the 2stage upgrade is still only 54mm to 54mm. The only 54mm M motor I'm aware of is the new Loki 54/4000 and it's 44" long (pretty good L/D ratio) same length as the entire booster section on the WM-3.
rms
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You could go 3" MD with a 75mm M motor for the booster and 3" with a 54mm mmt in the sustainer. With a GLR low profile retainer you should be able to get the interstage coupler to fit.
agrippo
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It's a kit, modify it to your hearts content and do what you want with it. Why would you have to fly it as offered from the manufacturer? Leave out the 54mm motor mount in the booster, cut the fin tabs off and it will rock an "M". You can actually build it faster without all that internal work.
Timers still make a good solution for backup deploy.
Plus a rocket that safely flies on the central motor should be ok to light air starts soon after liftoff with a timer.
One should examine the igniter he uses and the time to full pressure of the air start. No sophisticated device will be able to know if the motor takes too long to light.
Planning on doing air starts near apogee are not a good idea either way.
Just my opinion and am glad to see a thorough discuss on a topic that needs open discussion.
I didn't say you couldn't modify it.
I simply stated that it can't support an M to an L flight profile WITHOUT modifications. I am commenting to the OP post that states he's using a two stage KIT, not a modified two stage rocket. The Wildman 3 comes with very explicit step by step instructions from Tim on the build that must be followed to not void the lifetime warranty, it even goes even goes as far as mandating what adhesives must be used to keep the warranty in affect. So yes, you certainly could go MD on the booster and run 76mm motors, but this now becomes a modified two stage rocket.
ColumbiaNX01
Red blooded white American male
The project I am doing is a M1850 booster min diam. Then stages to a L1090 in a 3 inch airframe with a 54mm hole. All carbon except the nose cone.
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Agree that Timers as deployment backup are acceptable.
Just lighting motors with a bare, unconditioned timer is a bad idea and there are much safer alternatives available today.
Safety first.
Just lighting motors with a bare, unconditioned timer is a bad idea and there are much safer alternatives available today.
Safety first.
CORZERO
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And this is why:
[video=youtube;1VAkWgbCtA4]https://www.youtube.com/watch?v=1VAkWgbCtA4[/video]
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Corzero - that is EXACTLY why you don't want timers to light the second stage....great example.
ColumbiaNX01
Red blooded white American male
That is bad. But number 1 is that it did not have enough thrust. I think the booster stage of any 2 stage rocket should be 15/1 thrust to weight ratio.
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Also example of 2 failures made this more hazardous. The second failure was the recovery altimeter failing to detect apogee and deploy the main chute on the sustainer. If it had the sustainer ignition would have been less hazardous.
I was a little bit behind and north (right) of the guy with the camera. Those people off to the north (right) were further out in the field but the scary thing
is the rocket flopping around it could have very well headed in their direction. I believe the conclusion is the rocket was under powered in the first stage.
Kurt
rharshberger
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5:1 Thrust to Weight ratio is 5:1 whether the rocket weighs 5 lbs or 50 lbs.
Edited to remove under-powered reference.
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dixontj93060
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Underpowered? I don't think so. Velocity looks good leaving the rail. The slowdown and flip--clearly unstable.
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