Flightsketch mini questions

The Rocketry Forum

Help Support The Rocketry Forum:

bobbyg23

Well-Known Member
TRF Supporter
Joined
Apr 15, 2020
Messages
368
Reaction score
211
I received my flightsketch mini today and I have some questions. I have it mounted with shock cord to the nosecone loop as I don't have a cargo bay to put it in. I didn't drill any holes in the body tube yet. Here is the data I got. Not sure if it is accurate.
I am wondering if I need to drill holes in the bt or not. If I do drill holes, will they affect the ejection charge? Manual says you may have to drill 3 holes each 1/16".
 

Attachments

BEC

Well-Known Member
Joined
Feb 19, 2009
Messages
3,086
Reaction score
234
Location
Auburn, WA
All altimeters will give better, more accurate results if they can "see" the static air pressure outside the model essentially in real time. That's why you need static ports. The FS Mini has no special requirements in this regard.

The size of holes you need really depends on the volume of the compartment in which the altimeter is riding on its way up. The object is to size them so that there is little time lag between the pressure inside the body (prior to ejection) and outside.

Tell us a little more about your model (and motor). With an apogee around 200 feet and that short of a burn (though the FS Mini's burn time calculations are sometimes right on and sometimes not so much) I'm guessing something small with an Estes A8 for power. The altitude graph also suggests to me a delay that was a little too long and both traces say your recovery was kind of turbulent (tumbling or spinning or something).

Three 1/16 inch holes will not vent enough of your ejection charge to matter unless things are really marginal in your model with respect to getting the recovery system deployed already.

I don't see your flight in the online log, so you must not have uploaded it there, so my comments are based on your screen shots only and not looking more closely.
 

dlb

Sky Pyrate...
Joined
Jan 24, 2009
Messages
1,200
Reaction score
36
3 1/16 holes work just fine.
I also put mine a bt 20 coupler , for protection. 1 end open the other end sealed.
 

bobbyg23

Well-Known Member
TRF Supporter
Joined
Apr 15, 2020
Messages
368
Reaction score
211
All altimeters will give better, more accurate results if they can "see" the static air pressure outside the model essentially in real time. That's why you need static ports. The FS Mini has no special requirements in this regard.

The size of holes you need really depends on the volume of the compartment in which the altimeter is riding on its way up. The object is to size them so that there is little time lag between the pressure inside the body (prior to ejection) and outside.

Tell us a little more about your model (and motor). With an apogee around 200 feet and that short of a burn (though the FS Mini's burn time calculations are sometimes right on and sometimes not so much) I'm guessing something small with an Estes A8 for power. The altitude graph also suggests to me a delay that was a little too long and both traces say your recovery was kind of turbulent (tumbling or spinning or something).

Three 1/16 inch holes will not vent enough of your ejection charge to matter unless things are really marginal in your model with respect to getting the recovery system deployed already.

I don't see your flight in the online log, so you must not have uploaded it there, so my comments are based on your screen shots only and not looking more closely.
It would not let me upload it for some reason. It just tells me I need to be logged in to upload data. I am logged into the site. Is there somewhere else I need to log into?
 

bobbyg23

Well-Known Member
TRF Supporter
Joined
Apr 15, 2020
Messages
368
Reaction score
211
3 1/16 holes work just fine.
I also put mine a bt 20 coupler , for protection. 1 end open the other end sealed.
Does it matter where on the bt the holes are?
 

BEC

Well-Known Member
Joined
Feb 19, 2009
Messages
3,086
Reaction score
234
Location
Auburn, WA
It would not let me upload it for some reason. It just tells me I need to be logged in to upload data. I am logged into the site. Is there somewhere else I need to log into?
You need to be logged into your account from the app (not your browser). Swipe to the right from the startup screen to see where the login prompt is. Unfortunately it doesn’t know if you’re logged in or not and once you do there is no good way off the login screen except to kill the app and restart it (which means downloading your data again). Your data from the last fight will be in the FS Mini until you arm the unit for launch again. It’s at that point the previous flight’s data is wiped.

E5CC708C-3288-4187-B19C-3B048F4DB9A2.jpeg

0DC3B3DF-F147-406D-B5F5-4911DFE01453.jpeg
 
Last edited:

BEC

Well-Known Member
Joined
Feb 19, 2009
Messages
3,086
Reaction score
234
Location
Auburn, WA
On a model that big, I’d actually use three or four 1/8 inch holes. Ideally they should be down below the nose cone a ways so the air has a chance to smooth out after going over the nose cone/body tube joint. But unless you’re looking for very precise data for the whole flight (as opposed to knowing how high it went) the placement, as long as they are in the body somewhere away from big bumps, is not critical.

Added: I had to go look at your build thread - that is one cool model.

Also, the NAR cert data says the C11 takes nearly 0.35s to come to full thrust....so the FS Mini’s velocity curve and statistics about burn time and such are clearly not so good in this case. https://www.nar.org/SandT/pdf/Estes/C11.pdf
 
Last edited:

bobbyg23

Well-Known Member
TRF Supporter
Joined
Apr 15, 2020
Messages
368
Reaction score
211
You need to be logged into your account from the app (not your browser). Swipe to the right from the startup screen to see where the login prompt is. Unfortunately it doesn’t know if you’re logged in or not and once you do there is no good way off the login screen except to kill the app and restart it (which means downloading your data again). Your data from the last fight will be in the FS Mini until you arm the unit for launch again. It’s at that point the previous flight’s data is wiped.

View attachment 414110
View attachment 414109
Thank you very much. I just uploaded it now.
 

BEC

Well-Known Member
Joined
Feb 19, 2009
Messages
3,086
Reaction score
234
Location
Auburn, WA
Yes, I see it. I was about to suggest you edit in a title, but I see you did that and put in two pictures as well. Love the liftoff shot!
 
Last edited:

bobbyg23

Well-Known Member
TRF Supporter
Joined
Apr 15, 2020
Messages
368
Reaction score
211
On a model that big, I’d actually use three or four 1/8 inch holes. Ideally they should be down below the nose cone a ways so the air has a chance to smooth out after going over the nose cone/body tube joint. But unless you’re looking for very precise data for the whole flight (as opposed to knowing how high it went) the placement, as long as they are in the body somewhere away from big bumps, is not critical.

Added: I had to go look at your build thread - that is one cool model.

Also, the NAR cert data says the C11 takes nearly 0.35s to come to full thrust....so the FS Mini’s velocity curve and statistics about burn time and such are clearly not so good in this case. https://www.nar.org/SandT/pdf/Estes/C11.pdf
That makes sense then. It is not kicking in until a little bit into the flight. After examining the video on my phone, it looks like a total of 5ish seconds to apogee.
 

BEC

Well-Known Member
Joined
Feb 19, 2009
Messages
3,086
Reaction score
234
Location
Auburn, WA
Oh...and if you’re going to keep flying the FS Mini just hanging from the nose cone, you really ought to protect it from the ejection gases some. Yesterday evening when I was flying one in a small model (Semroc Astro Jr.) down at the nearby elementary school, I was just folding a square of wadding into thirds and then wrapping that around the FS Mini as I stuffed it into the top of the tube above the ‘chute and shock cord. In a model like yours, where you have lots more room, dlb’s idea of a JT-20 as a sort of protective shell would work. When I fly one in a larger model (BT-50 and up) but in with the recovery system, I put it in a little fleece fabric pouch my wife made.

2C087823-48EF-4CBE-825D-3F11423E0334.jpeg
B5FA784B-0904-4799-9161-943B9B010ECB.jpeg
 

bobbyg23

Well-Known Member
TRF Supporter
Joined
Apr 15, 2020
Messages
368
Reaction score
211
On a model that big, I’d actually use three or four 1/8 inch holes. Ideally they should be down below the nose cone a ways so the air has a chance to smooth out after going over the nose cone/body tube joint. But unless you’re looking for very precise data for the whole flight (as opposed to knowing how high it went) the placement, as long as they are in the body somewhere away from big bumps, is not critical.

Added: I had to go look at your build thread - that is one cool model.

Also, the NAR cert data says the C11 takes nearly 0.35s to come to full thrust....so the FS Mini’s velocity curve and statistics about burn time and such are clearly not so good in this case. https://www.nar.org/SandT/pdf/Estes/C11.pdf
Those holes will not affect the ejection charge then, right? I have 2 other rockets that I plan on putting it into also. Estes SLV and Estes QCC explorer. I will put some holes in those also. Is there a method to getting those hole into the BT? Just drill them or add some CA to harden the edges?
 

bobbyg23

Well-Known Member
TRF Supporter
Joined
Apr 15, 2020
Messages
368
Reaction score
211
Oh...and if you’re going to keep flying the FS Mini just hanging from the nose cone, you really ought to protect it from the ejection gases some. Yesterday evening when I was flying one in a small model (Semroc Astro Jr.) down at the nearby elementary school, I was just folding a square of wadding into thirds and then wrapping that around the FS Mini as I stuffed it into the top of the tube above the ‘chute and shock cord. In a model like yours, where you have lots more room, dlb’s idea of a JT-20 as a sort of protective shell would work. When I fly one in a larger model (BT-50 and up) but in with the recovery system, I put it in a little fleece fabric pouch my wife made.

View attachment 414118View attachment 414119
I like that idea. I will have to do that.
 

bobbyg23

Well-Known Member
TRF Supporter
Joined
Apr 15, 2020
Messages
368
Reaction score
211
There are some weird things on my flight data. I think the holes will make that better next time.
 

BEC

Well-Known Member
Joined
Feb 19, 2009
Messages
3,086
Reaction score
234
Location
Auburn, WA
The SLV, of course, has a huge payload compartment....so you can put it in there. The trick will be keeping it from rattling around. And of course the payload section will need static ports. For the QCC you’ll want to do the same as for your upscale Sidekick (unless you modded it to have a payload section as I typically do).

As for the ejection charges....three or four 3/32 or 1/8 inch holes will probably not be an issue getting a 12 inch ’chute out of a BT-60 (well, as long as the nose cone is not too tight on the tube).

Funny data hopefully will be improved by having static ports.
 

bobbyg23

Well-Known Member
TRF Supporter
Joined
Apr 15, 2020
Messages
368
Reaction score
211
The SLV, of course, has a huge payload compartment....so you can put it in there. The trick will be keeping it from rattling around. And of course the payload section will need static ports. For the QCC you’ll want to do the same as for your upscale Sidekick (unless you modded it to have a payload section as I typically do).

As for the ejection charges....three or four 3/32 or 1/8 inch holes will probably not be an issue getting a 12 inch ’chute out of a BT-60 (well, as long as the nose cone is not too tight on the tube).

Funny data hopefully will be improved by having static ports.
I have not modded any of them to have a payload section. They are built per the instructions. The SLV has the nosecone glued on so I do not have access to the payload compartment. I will have to take a look at how I can easily gain access to that compartment.
 

Buckeye

Well-Known Member
Joined
Sep 6, 2009
Messages
2,376
Reaction score
293
Did your rocket land in a 161 ft deep well? ;)

Edit: I see it landed in water. That probably has something to do with it!
 

bobbyg23

Well-Known Member
TRF Supporter
Joined
Apr 15, 2020
Messages
368
Reaction score
211
Ha. Funny things happen when it gets wet.
 
Top