75mm Deuce (redo)

After my last thread got bashed by everyone telling me to slow down I decided to start it over for the sole purpose of the build. I have heard your opinions and I have drawn out my plan and talked with some poeple about it. I have showed them my plans and they said if I stick to that plan solely it will be fine. On to specs:

BT
<li> 8" peeled quickrete tube
<li> 1 layer of 10oz FG using aeropoxy

Fincan
<li> 1/2" carbon honeycomb fins
<li> 10.9oz CF
<li> one veil layer of 3oz FG
<li> 34" long 75mm LOC MMT
<li> 3X1/2" aircraft grade CR's
<li> WS epoxy using chopped CF and collodial silica for gluing.

Nosecone and Ebay
<li> 8" foam nosecone
<li> 2 layers of 2oz FG on cone
<li> 2X1/2" ply bulkhead glued together for Ebay ends
<li>2 1" SS ubolts on center
<li> 4 10-24 all threads
<li> Missileworks switches (main power and shunts)

Recovery
<li> 1" Y harness 24" long from Ebay end
<li> 9/16" main shockcord
<li> 52" TAC drouge
<li> 15' main chute in D-bag
<li> 24" pilot chute

Those are all the specs I have so far. If there is anything you want to know let me know. If you have an issue with this Pm me or post it in the old thread

thanx, Ben

Here are both 8" tubes stacked on each other with the MMT's in front. (No it won't be this long when complete )

<a href="https://www.putfile.com/pic.php?img=3822999"><img src="https://img1.putfile.com/thumb/10/29922475035.jpg" alt="Click to enlarge"></a>

thanx, Ben

My .014 mylar and 9.6oz FG arrived from CST. My West Systems and missileworks switches also arrived.

<a href="https://www.putfile.com/pic.php?img=3900377"><img src="https://img1.putfile.com/thumb/11/30719473414.jpg" alt="Click to enlarge"></a>

I also did a little work witht he BT. I cut the coupler and tacked it

<a href="https://www.putfile.com/pic.php?img=3900378"><img src="https://img1.putfile.com/thumb/11/30719473456.jpg" alt="Click to enlarge"></a>

thanx, Ben

Here is the lower tube. It has been primed onced and the white stuff is spackling that is filling the larger divets. I will sand it with 220 later.

<a href="https://www.putfile.com/pic.php?img=4592130"><img src="https://img1.putfile.com/thumb/1/2316035779.jpg"></a>

thanx, Ben

I can tell you right now, those fins will flutter if you decide to push it at all. For lower range 75mm motors, you'd be fine, but if that thing really gets moving, those will definitely flutter.

Originally posted by ben
After my last thread got bashed by everyone telling me to slow down

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Oh - and yes, we really do have a reason for telling you that...

Ben,

I didn't follow the fin construction, 1/2 inch CF HC? This needs to be reinforcd probaly with an additional 2 layers of CF before the tip to tip. The one thing that is really working in your favor is the fin thickness--1/2 inch is stout stuff and even ply in this width can have flutter velocities beyond MACH 1.
JS

Yes, it can, but I think it'll need some serious reinforcement in this case due to the sheer size of the fin. You commented on my fins' huge size, and these would be another 33% on top of that.

Ben, what happened to "putting this project aside for a while"?

Originally posted by rocketkyle
Ben, what happened to "putting this project aside for a while"?

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I was kind of wondering this myself.

Ben, just don't get any ideas of flying this on 75mm W9 motors though.

just remember you cant climb a latter untill you step on the first rung BEN

Originally posted by Bowhunter
just remember you cant climb a ladder untill you step on the first rung BEN

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and you cant get to the top until you step on the second rung (asuming the ladder is more than 2 rungs high).

OK I fixed it LATTER I need a new key Board I cant see

Originally posted by cjl
Yes, it can, but I think it'll need some serious reinforcement in this case due to the sheer size of the fin. You commented on my fins' huge size, and these would be another 33% on top of that.

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Hope he has a pickup truck
JS

I just wished that he had taken the advice of all of us in the first thread he posted about this project.

Ben, we are not slamming you by any means, it's just that you are literally in over your head in shark infested waters with this project. It would have been much better had you gotten your feet wet with a much more simple project powered by a single H, I or maybe even a small J motor like a J350W/J420R.

Just curious but do you have ANY idea of just how much power a single 75mm motor puts out???

I would just be afraid of the motor mount assembly suffering a catastrophic failure, resulting in two 75mm motors flying unrestrained all over the place and since most 75mm motors have burn times in excess of 4 seconds, those motors are going to go for awhile before finally burning out and coming to rest, hopefully away from the flight line.

Ben, just take it easy and enjoy your ride down the rocketry freeway, don't be in such a hurry to get somewhere.

Originally posted by Donaldsrockets

Just curious but do you have ANY idea of just how much power a single 75mm motor puts out???

I would just be afraid of the motor mount assembly suffering a catastrophic failure, resulting in two 75mm motors flying unrestrained all over the place and since most 75mm motors have burn times in excess of 4 seconds, those motors are going to go for awhile before finally burning out and coming to rest, hopefully away from the flight line.

Ben, just take it easy and enjoy your ride down the rocketry freeway, don't be in such a hurry to get somewhere.

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Lets see a C motor is about 10 N-s. A single small M about 600 C's.

Yup, about equiv to 600 C6's staged to another 600 C's, for a burn time of 4+ seconds. I find when it gets put in terms of small motors, people better appreciate the forces being dealt with.
JS

outlineing each component doesnt mean its any better than the last design.

Originally posted by ben
Here is the lower tube. It has been primed onced and the white stuff is spackling that is filling the larger divets. I will sand it with 220 later.

<a href="https://www.putfile.com/pic.php?img=4592130"><img src="https://img1.putfile.com/thumb/1/2316035779.jpg"></a>

thanx, Ben

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Why bother even starting the painting process when its not even built yet?

Originally posted by Chrisn
Why bother even starting the painting process when its not even built yet?

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its easier to smooth out the rough spots before I have huge fins to work around.


thanx, Ben

Originally posted by ben
its easier to smooth out the rough spots before I have huge fins to work around.


thanx, Ben

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Epoxy (and therefore, your fins and fiberglass) will stick much better to a raw, pealed tube than it will to spackling and primer. I think you're getting ahead of yourself again...

SE

Originally posted by SteelyEyed
Epoxy (and therefore, your fins and fiberglass) will stick much better to a raw, pealed tube than it will to spackling and primer. I think you're getting ahead of yourself again...

SE

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I am going to rough up the fin spots with 60 and 80 grit before I glue them on.

thanx, Ben

hows that stop the fins getting in the way?

Ben,

Look I'm here to help if I can--you want to build this even tho it may be way beyond your experience level, its your $$. It will be a heads up flight and I hope you have a mentor who can help prep, make igniters that go wham, etc unless you're only CTI, etc.

the spackling to fill dents was ok, but the primer not so good. Sand some off. You must have at least 2 good layers of 6 oz fg on your fin can before proceeding. They can be wrapped at the same time, or not. theres all kind of info over on info central on how to do this if its your first time with FG. As to whether you cut the holes for the deuce tubes first, either way--it it were me I would cut them out after FGing as you'll just have to cut the FG again and may get some leaking into the BT if done first.

Go slow, as most mistakes are avoidable, a few are fixable, and all a pain in the arse.
JS

Originally posted by denverdoc
Hope he has a pickup truck
JS

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And a trashbag for recovery.


Priming your tube beforehand was a bad choice. Not only are you not going to get as good a bond to a smooth surface than a rough one, but you are making more work for yourself in the long run because you are only going to need to resmooth the fincan area.

Originally posted by Ryan S.
And a trashbag for recovery.

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Thats funny. But I'd like to think that with some oversight, Ben might still pull this off. I do think FGing the tubes after roughing them up will be workable. Needs something that he can glue those honkin fire flapper fins to. I would not trust a bond to the peeled tube, tho with enuf tip to tip afterwards it might be made to work...
JS

Originally posted by denverdoc
Ben,

Look I'm here to help if I can--you want to build this even tho it may be way beyond your experience level, its your $$. It will be a heads up flight and I hope you have a mentor who can help prep, make igniters that go wham, etc unless you're only CTI, etc.

the spackling to fill dents was ok, but the primer not so good. Sand some off. You must have at least 2 good layers of 6 oz fg on your fin can before proceeding. They can be wrapped at the same time, or not. theres all kind of info over on info central on how to do this if its your first time with FG. As to whether you cut the holes for the deuce tubes first, either way--it it were me I would cut them out after FGing as you'll just have to cut the FG again and may get some leaking into the BT if done first.

Go slow, as most mistakes are avoidable, a few are fixable, and all a pain in the arse.
JS

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so if I understand this I need to add another layer on BEFORE I put the fins on? I already have a layer of 10oz and a layer of 2oz veil put on with Aeropoxy. I planned on t2ting with some 10oz carbon since it will only be 200bux total for 10oz t2t. but for 8 oz it is 250bux (kinda weird )

thanx, Ben

I forgot to add. I am going to foam the fin can so I can add a little more rgidity to the lower section.

thanx, Ben

No 10 oz plus 2 is equivalent, more or less, but the veiled stuff is a little more prone to delam, so might want to sand that off where the fins go--I like the idea of the fins being glued to the beefy glass, but if the 10 and 2 were laid at the same time so you have a primary bond, likely not critical. If the first was allowed to cure, and then the veil applied, I'd definitely sand down to the good stuff,
J

Originally posted by denverdoc
No 10 oz plus 2 is equivalent, more or less, but the veiled stuff is a little more prone to delam, so might want to sand that off where the fins go--I like the idea of the fins being glued to the beefy glass, but if the 10 and 2 were laid at the same time so you have a primary bond, likely not critical. If the first was allowed to cure, and then the veil applied, I'd definitely sand down to the good stuff,
J

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I figured I would sand down to nice roughn area for the fins. My next step it cutting MMT Cr's. More to come later.

thanx, Ben

Ben,
I would like to ask why you're going against everyone's advice and building it anyway. With your lack of experience, this thing is very dangerous, and I can only hope that someone stops you from flying it. You're 13... you have a LONG time to work on building skills and work up to this point. And you haven't even flown an H motor... With your knowledge and building skills right now, you could very well ruin this thing and throw all of your money away. I can tell you that you will be much happier with the results if you wait just 5 years before building it.