Difuminar: 9400 feet and Mach 1.6 on a CTI G150

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Yep slow down and take your time Abdr. I know you want to see it together to see what it looks like but now during assembly it is even more important to proceed with the same attention to detail you had during the design and simming phase. From those sims you discovered that very small things make appreciable differences in altitude; well so does making sure it is assembled as precisely, accurately and with correct methods for the adhesives you are using. CA is not a good choice for the fin root to body joint. You have the fin guide so CA need not be used at all.
If you want to discuss further or have questions, PM me and I will give you my phone number. I want to see this rocket fly succesfully at the Rage and I am willing to help you.

Greg
 
Take your time! You have invested a lot of time on a good design. You invested a bunch of money in great parts. Why not maximize you investment with good assembly techniques. A great assembly can yield unexpected performance. All your research and enthusiasm proves finishing it off great is well within your capabilities.
Yeah, i will try that.

Yep slow down and take your time Abdr. I know you want to see it together to see what it looks like but now during assembly it is even more important to proceed with the same attention to detail you had during the design and simming phase. From those sims you discovered that very small things make appreciable differences in altitude; well so does making sure it is assembled as precisely, accurately and with correct methods for the adhesives you are using. CA is not a good choice for the fin root to body joint. You have the fin guide so CA need not be used at all.
If you want to discuss further or have questions, PM me and I will give you my phone number. I want to see this rocket fly succesfully at the Rage and I am willing to help you.

Greg
I will try JB weld for the tracking but there is one problem. When I am placing the fins onto the body tube, some excess glue escapes from the sides and that tends to make the fin guide stick to the fins. What should i do about this?

I've seen a couple of them but I've also seen the blackhawk's instruction manual for the blackhawk 24, and that is the method I'm planning to use now.
 
Yeah, i will try that.

I will try JB weld for the tracking but there is one problem. When I am placing the fins onto the body tube, some excess glue escapes from the sides and that tends to make the fin guide stick to the fins. What should i do about this?

I've seen a couple of them but I've also seen the blackhawk's instruction manual for the blackhawk 24, and that is the method I'm planning to use now.

The corners of the fin guide that would interfere with the glue joint should be cut out a bit to allow it to not stick to the glue. Looking at the guide, it should have the reverse profile of the rocket with fins installed and fillets applied. Also when attaching fins with any epoxy such as JB Weld, mix it up and allow it to sit for 10-15 minutes to let I thicken up a tad before applying to the fin root edge. Also use less than you think you will need. Just a skim on the edge will suffice for tacking on. Also sand the fins on the root edge AND the area where the fillets will will be applied BEFORE tacking them on.
 
The corners of the fin guide that would interfere with the glue joint should be cut out a bit to allow it to not stick to the glue. Looking at the guide, it should have the reverse profile of the rocket with fins installed and fillets applied. Also when attaching fins with any epoxy such as JB Weld, mix it up and allow it to sit for 10-15 minutes to let I thicken up a tad before applying to the fin root edge. Also use less than you think you will need. Just a skim on the edge will suffice for tacking on. Also sand the fins on the root edge AND the area where the fillets will will be applied BEFORE tacking them on.
Ok i will try that. But the fin guide looks like this.

View attachment 316749
 
Ok, so i just spent 30 min cleaning up the fins and body tube with some sandpaper. I stack standed and rebeveled them and then sandpapered them to remove the CA.
 
Take a hobby knife to it and cut off the corners to allow room for the glue. Even so, you should also use to epoxy sparingly to avoid any big globs of it gluing your fin guide to the rocket
Ok i will try that.
 
If you have a triangle or round file, file right at the fin slot base to remove the corners.
Dremel tool with a sanding drum would work to.
I have a dremel so i can try that. I dont know where it is though so i guess i will have to do a little searching around.
 
Another good habit is to weigh everything during the build. Even the adhesive used. Enter the corrected mass or dimension of each component in your sim. If you check often you may be able to spot and correct potential performance robbing problems. In the end actual loaded ready to fly mass and CG need to be entered into the sim. All this is very useful when anilizing the post flight data. Pressure waves impacting on the airframe can cause wild barometric data. If you have a great detailed sim it will provide a good benchmark. I had a just barely mid power supersonic flight but my Pnut came back with numbers near Mach 2.6. The sim provided reality when the altitude of the sim and post flight data were within 7 feet of each other. The culprit was baro sampling ports to close to the nose cone shoulder. The raw data from the altimeter showed a spike in the first .3 seconds. This spike was a pressure wave that did not dissipate until the rocket went back to subsonic. All the data was corrupt. Details, you have done great with the design don't let up now.
 
Another good habit is to weigh everything during the build. Even the adhesive used. Enter the corrected mass or dimension of each component in your sim. If you check often you may be able to spot and correct potential performance robbing problems. In the end actual loaded ready to fly mass and CG need to be entered into the sim. All this is very useful when anilizing the post flight data. Pressure waves impacting on the airframe can cause wild barometric data. If you have a great detailed sim it will provide a good benchmark. I had a just barely mid power supersonic flight but my Pnut came back with numbers near Mach 2.6. The sim provided reality when the altitude of the sim and post flight data were within 7 feet of each other. The culprit was baro sampling ports to close to the nose cone shoulder. The raw data from the altimeter showed a spike in the first .3 seconds. This spike was a pressure wave that did not dissipate until the rocket went back to subsonic. All the data was corrupt. Details, you have done great with the design don't let up now.
Ya i will do that.
 
I was sanding around the base lightly with 200 grit and the tip just broke off. These fins seem very weak, I'm thinking of ditching them and trying for 1/16" fins from here (https://dragonplate.com/ecart/product.asp?pID=3651&cID=67). If they cant hold up to light sanding then there is no way they can hold up to mach 1.6 flight.

The forces applied to your fins during flight are in a totally different direction than the forces you applied while sanding. You can probably still use that fin. When you tack it on with JBweld, add a tiny little amount to the brokeken piece. When you add your fillets, it will further strenthen the broken area. Don't give up and more importantly, take your time! Do not rush this project!
 
The forces applied to your fins during flight are in a totally different direction than the forces you applied while sanding. You can probably still use that fin. When you tack it on with JBweld, add a tiny little amount to the brokeken piece. When you add your fillets, it will further strenthen the broken area. Don't give up and more importantly, take your time! Do not rush this project!
Do you think i should seal the leading edges of the fins with JB weld to prevent delamination? The tips of the fins are very brittle and im afraid that they will come off during the boost.
 
By the way.......... fins are Dragon Plate. No need to seal the leading edges. I seriously doubt if this thing will be in Mach long enough to heat/soften any glue.

You're overthinking all this...tack fins on, do fillets, it will be fine...if it survives the small fin size.

They will not come off unless it tumbles/goes unstable.
I would be way more worried about getting a tracker in there, so I could find it.

[PS.. the guy that wrote the BlackHawk instructions] :smile:
 
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By the way.......... fins are Dragon Plate.

You're overthinking all this...tack fins on, do fillets, it will be fine...if it survives the small fin size.

They will not come off unless it tumbles/goes unstable.

[PS.. the guy that wrote the BlackHawk instructions] :smile:
Ok thanks i will try that.
 
PS this is how you fix guides so glue oozing out from fin won't glue guide to airframe.

Just file/sand off edges on slot.

100_7801.jpg 100_7803.jpg


Now just go & build the darn thing! Preferably fly it at a 2 day launch , [on the first day] so you increase the chance of recovery. Some one out looking for their rocket, may find yours!!!

Good luck. Remember this: when doing extreme projects, most of us have about a 50/50 rate of success, in getting stuff back in one piece. :dark:
 
PS this is how you fix guides so glue oozing out from fin won't glue guide to airframe.

Just file/sand off edges on slot.

View attachment 317053 View attachment 317054


Now just go & build the darn thing! Preferably fly it at a 2 day launch , [on the first day] so you increase the chance of recovery. Some one out looking for their rocket, may find yours!!!

Good luck. Remember this: when doing extreme projects, most of us have about a 50/50 rate of success, in getting stuff back in one piece. :dark:
Yes Im planning to fly it on the 1st day of launch because thats when all the good launches are but unfortunately i wont be staying for the full two days. Im using a telemini for tracking to increase chances of recovery tho.
 
Im using a telemini for tracking to increase chances of recovery tho.


Well alrighty then !!!!!!!! Best decision you've made so far....you can use that for many rockets, congrats.

You are going to love that thing! I tracked a carbon 29mm to over 11,000 ft & walked right up to it, a little over 1/2 mile away.

Make sure you practice with it, before putting in a rocket, till you feel real comfortable using it. I put it on top of my mailbox and drove away from it till I lost signal. Drove back at it from several directions practicing.
 
Well alrighty then !!!!!!!! Best decision you've made so far....you can use that for many rockets, congrats.

You are going to love that thing! I tracked a carbon 29mm to over 11,000 ft & walked right up to it, a little over 1/2 mile away.

Make sure you practice with it, before putting in a rocket, till you feel real comfortable using it. I put it on top of my mailbox and drove away from it till I lost signal. Drove back at it from several directions practicing.
Yeah that is what Ill try. For the first flight to test out the systems ill go for a D12 (should get about 1200 ft) and ill test the telemini out with that.
 
Yeah that is what Ill try. For the first flight to test out the systems ill go for a D12 (should get about 1200 ft) and ill test the telemini out with that.

I think what Jim is saying is you should practice with the telemini on the ground to make sure you know how to use it even before you launch it in any rocket.
 
I think what Jim is saying is you should practice with the telemini on the ground to make sure you know how to use it even before you launch it in any rocket.
I have experience rdf tracking and will be at the same launch, I can give him a hand if he needs it.
Greg
 
I think what Jim is saying is you should practice with the telemini on the ground to make sure you know how to use it even before you launch it in any rocket.
Ok i will try that.

I have experience rdf tracking and will be at the same launch, I can give him a hand if he needs it.
Greg
thanks. i think i will be launching at petitcodiac.
 
Ok i glued on the piece with CA back onto the fin. Pics will follow.
 
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