Hi Dale,
One more point. The more I thought about my answer the more I wanted to
clarify something.
First my assumption that a rocket takes 1 second to leave the rail is as
assumption... I've seen some leave much faster. So you want your max
thrust to occur before one second but at least by one second. The
sooner the safer.
So here is the way I calculate my launch conditions."
Lets say your motor gives you a max F:W ratio of 10:1 within the first 1
second of burn, then you are probably ok. The ramp up from 0 to max
thrust giving a F:W ratio of 10:1 in one second will probably cover you.
However, if your motor gives you a max F:W of 5:1 within the first
second of burn, I'd be worried; especially if you are launching on a
windy day (and I'd make the calculation based on a full rocket motor
just to be one the safe side.)
So my two ground rules for my launches are:
1. Pick motors that, if possible, get me to F:W ratio of 6:1 to 10:1 in
the first second of burn.
2. Don't use a motor that gives me a F:W ratio of 5:1 or less in the
first second of burn under any circumstances. There are so many motors
out there to choose from that there is no need to cut it close.
And as stated by others, there are several programs on the internet that
attempt to simulate lift off and altitude with various motors. Try
several of them and see what motors always come up as working for you.
The ones that some programs say are marginal are probably ones to stay
away from.
I hope this makes even more sense than my previous email. This is what
I think, makes our hobby so much fun... all the hours and days and
months of thinking that goes into our 30 seconds of intense excitement!!
Be well,
Steven
Steven Cerri, B.S. Aero, M.S. Geophysics, MBA
Author of: "The Fully Integrated Engineer: Combining Technical Ability
and Leadership Prowess",
published by Wiley and IEEE
STCerri International
231 Market Place, Suite 320
San Ramon, CA 94583-4743 USA
Office: 925-735-9500
Email: steven@xxxxxxxxxxx
Website: www.stevencerri.com
-------- Original Message --------
Subject: [tccrockets] Re: Proper motor calc?
From: Dale <Dale@xxxxxxxxxx>
Date: Mon, April 22, 2019 2:30 pm
To: "tccrockets@xxxxxxxxxxxxx" <tccrockets@xxxxxxxxxxxxx>
That makes sense and less to input into the calculators... :) It looks like
the J135 as well as most of these hit just about their peak within the first
second. So, I'd be looking at 6 to 1 at liftoff.
Thanks!!! The K185 too looks like it would be nice... I like the long burns
the best! :)
Very truly,
Dale
Dale S. Soutas Financial Planner
333 West Shaw Avenue, Ste 106 | Fresno, CA 93704
toll free 800.887.2348 | PHONE 559.230.1648 | FAX 559.230.1651
dale@xxxxxxxxxx | soutas.com
Investment advisory services offered only by duly registered individuals
through AE Wealth Management, LLC (AEWM). AEWM and Soutas Financial &
Insurance Solutions Inc are not affiliated companies.
Investment advisory services offered through AE Wealth Management, LLC.
Soutas Financial & Insurance Solutions, Inc. is an independent financial
services firm that creates retirement strategies using a variety of
investment and insurance products. Neither the firm nor its representatives
may give tax or legal advice. Investing involves risk, including the
potential loss of principal. No investment strategy can guarantee a profit or
protect against loss in periods of declining values. Any references to
protection benefits or lifetime income generally refer to fixed insurance
products, never securities or investment products. Insurance and annuity
product guarantees are backed by the financial strength and claims-paying
ability of the issuing insurance company.
It is important that you do not use email to request, authorize or effect the
purchase or sale of any security, to send fund transfer instructions, or to
effect any other transactions. Any such request, orders, or instructions that
you send will not be accepted and will not be processed. The text of this
communication is confidential, and use by any person who is not the intended
recipient is prohibited. Any person who receives this communication in error
is requested to immediately destroy the text of this communication without
copying or further dissemination. Recipients should be aware that all emails
exchanged with the sender are automatically archived and may be accessed at
any time by duly authorized persons and may be produced to other parties,
including public authorities, in compliance with applicable laws.
-----Original Message-----
From: tccrockets-bounce@xxxxxxxxxxxxx
[mailto:tccrockets-bounce@xxxxxxxxxxxxx] On Behalf Of steven@xxxxxxxxxxx
Sent: Monday, April 22, 2019 11:56 AM
To: tccrockets@xxxxxxxxxxxxx
Subject: [tccrockets] Re: Proper motor calc?
Actually, you don't calculate safe lift off thrust to weight ratio on average
or peak thrust. Look at the thrust curve and find the thrust during the
first second of engine burn. Your rocket will leave the rail or tower in a
second or so. Therefore, that first part of the thrust curve is what to use
to calculate your lift off thrust to weight ratio.
If your rocket hasn't got sufficient speed by the time it leaves the rail it
won't have much stability control from the fins. A 5:1 lift off ratio with a
10 foot rail is the reason we calculate the ratios the way we do. If you had
a 20 foot rail, (rather than a 10 foot rail) then a longer time span could be
used to determine if the rocket reached flight stability.
I hope this helps.
Steven Cerri, B.S. Aero, M.S. Geophysics, MBA Author of: "The Fully
Integrated Engineer: Combining Technical Ability and Leadership Prowess",
published by Wiley and IEEE STCerri International
231 Market Place, Suite 320
San Ramon, CA 94583-4743 USA
Office: 925-735-9500
Email: steven@xxxxxxxxxxx
Website: www.stevencerri.com
-------- Original Message --------
Subject: [tccrockets] Proper motor calc?
From: Dale <Dale@xxxxxxxxxx>
Date: Mon, April 22, 2019 10:01 am
To: "tccrockets@xxxxxxxxxxxxx" <tccrockets@xxxxxxxxxxxxx>
I have a modified LOC Black Brandt (about 2.5ft shorter) weighs 7.2lbs with
everything minus motor & casings. If having a 5:1 ratio is minimum, when I
add 2.5lbs using a J135 I have 9.7lbs total lift off weight. When I
calculate the ratio on the average thrust verses I get 3.6: 1 and with the
peak thrust 6.3: 1. So, do we calculate the ratio for liftoff on the
average or peak thrust? Would this be a safe motor for this rocket weight?
Also, Rod Lovely, which K motor were you recommending after its maiden
flight?
Thanks,
Dale
[http://www.nextlevelproductions.info/2017signatures/soutas/i/logo.png
]
Dale S. Soutas Financial Planner
333 West Shaw Avenue, Ste 106 | Fresno, CA 93704
toll free 800.887.2348 | PHONE 559.230.1648 | FAX 559.230.1651
dale@xxxxxxxxxx<mailto:dale@xxxxxxxxxx> | soutas.com
Investment advisory services offered only by duly registered individuals
through AE Wealth Management, LLC (AEWM). AEWM and Soutas Financial &
Insurance Solutions Inc are not affiliated companies.
[http://www.nextlevelproductions.info/2017signatures/soutas/i/footer.p
ng]
Investment advisory services offered through AE Wealth Management, LLC.
Soutas Financial & Insurance Solutions, Inc. is an independent financial
services firm that creates retirement strategies using a variety of
investment and insurance products. Neither the firm nor its representatives
may give tax or legal advice. Investing involves risk, including the
potential loss of principal. No investment strategy can guarantee a profit
or protect against loss in periods of declining values. Any references to
protection benefits or lifetime income generally refer to fixed insurance
products, never securities or investment products. Insurance and annuity
product guarantees are backed by the financial strength and claims-paying
ability of the issuing insurance company.
It is important that you do not use email to request, authorize or effect
the purchase or sale of any security, to send fund transfer instructions,
or to effect any other transactions. Any such request, orders, or
instructions that you send will not be accepted and will not be processed.
The text of this communication is confidential, and use by any person who
is not the intended recipient is prohibited. Any person who receives this
communication in error is requested to immediately destroy the text of this
communication without copying or further dissemination. Recipients should
be aware that all emails exchanged with the sender are automatically
archived and may be accessed at any time by duly authorized persons and may
be produced to other parties, including public authorities, in compliance
with applicable laws.
From: tccrockets-bounce@xxxxxxxxxxxxx
[mailto:tccrockets-bounce@xxxxxxxxxxxxx] On Behalf Of Michael Gentile
Sent: Sunday, April 21, 2019 10:19 PM
To: tccrockets@xxxxxxxxxxxxx
Subject: [tccrockets] Re: April Launch
AeroTech order is going in tomorrow afternoon. If you need motors for
DA or beyond please order by 3pm. Sorry I meant to make an
announcement at the launch. Will there
be a Nike drag race? Do we need K2050’s?
Mike @ BAR
Sent from my BAR GREEN iPhone
On Apr 21, 2019, at 8:35 AM, aaron hagadorn
<hagadornclassics@xxxxxxxxx<mailto:hagadornclassics@xxxxxxxxx>> wrote:
Sounds like I missed a great launch. Damn work. Oh well guess that
means I have to be there for DA. Getting that itch to launch a few
rockets
Aaron
On Sat, Apr 20, 2019, 20:17 Michael Hall
<michaeldh1797@xxxxxxxxx<mailto:michaeldh1797@xxxxxxxxx>> wrote:
Hey guys, super fun launch today. We got back after the launch a found out
we are missing a aeroteck 54mm 852 casing that must have flown out of a
rocket today. Please let me know if anyone finds it.
Thanks,
Michael Hall
Uc Merced AIAA
On Fri, Apr 19, 2019, 10:03 PM aaron hagadorn
<hagadornclassics@xxxxxxxxx<mailto:hagadornclassics@xxxxxxxxx>> wrote:
Guys wish I could make it but we t working tomorrow to dig our selves
out of a mess. Hope it is a good launch and see y'all in may at DA2019
On Fri, Apr 19, 2019, 14:47 Steve Sawyer
<steve@xxxxxxxxxxxxxxxx<mailto:steve@xxxxxxxxxxxxxxxx>> wrote:
Wish we could make it for this year’s first launch but we have Easter
weekend plans. See you in May.
Steve
From:
tccrockets-bounce@xxxxxxxxxxxxx<mailto:tccrockets-bounce@xxxxxxxxxxxxx
[mailto:tccrockets-bounce@xxxxxxxxxxxxx<mailto:tccrockets-bounce@freel
ists.org>] On Behalf Of Ralovley (Redacted sender "Ralovley" for
DMARC)
Sent: Friday, April 19, 2019 10:00 AM
To: tccrockets@xxxxxxxxxxxxx<mailto:tccrockets@xxxxxxxxxxxxx>
Subject: [tccrockets] Re: April Launch
Hope to see everyone tomorrow!
Rod Lovley
Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------
From: James Dougherty <jafrado@xxxxxxxxx<mailto:jafrado@xxxxxxxxx>>
Date: 4/18/19 11:49 AM (GMT-08:00)
To: TCC chat
<tccrockets@xxxxxxxxxxxxx<mailto:tccrockets@xxxxxxxxxxxxx>>
Subject: [tccrockets] Re: April Launch
Thanks Mike
On Thu, Apr 18, 2019 at 3:17 AM Michael Gentile
<smmike@xxxxxxxxxxx<mailto:smmike@xxxxxxxxxxx>> wrote:
BAR will be there. 8am it is!
Mike @ BAR
Sent from my BAR GREEN iPhone
On Apr 18, 2019, at 12:28 AM, James Dougherty
<jafrado@xxxxxxxxx<mailto:jafrado@xxxxxxxxx>> wrote:
Hey Folks,
NOTAM is hot, we're cleared for SFC to 17K MSL on Saturday.
Like Rod said, lets all try to show up at 8am sharp!
Woohoo - get your rockets ready!
-James
On Sat, Apr 13, 2019 at 5:00 PM James Dougherty
<jafrado@xxxxxxxxx<mailto:jafrado@xxxxxxxxx>> wrote:
Yes, first launch of the year in April - and just think, we've been rained
out all year!!!
So I expect it to be epic beautiful out there ... I am sure we will have a
great time.
Rockets!
On Sat, Apr 13, 2019 at 4:46 PM Bruce Rohn
<bhrohn@xxxxxxxxx<mailto:bhrohn@xxxxxxxxx>> wrote:
Hard to believe it will be first launch of the year.
I expect A LOT of rockets!!
On Sat, Apr 13, 2019, 3:18 PM Ralovley
<dmarc-noreply@xxxxxxxxxxxxx<mailto:dmarc-noreply@xxxxxxxxxxxxx>> wrote:
Hey Boys and Girls!
Who's ready to launch some rockets?? Looks like everything is a go
for next Saturday's TCCs Launch! Set up time will be at 8am. Please
come help out with the set up and teardown! The more people that can
volunteer is appreciated alot! The weather as of now looks
outstanding! NO MUD!😆
See you all there!
Rod Lovley
Sent from my Verizon, Samsung Galaxy smartphone
