L3 Build

Advertise with us
Shop deals on ebay
the model rocket show
The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Titan II said:
https://www.google.com/search?q=1010+1515+slot+size&tbm=isch&source=iu&ictx=1&fir=wmV_2HoRpTpjlM%3A%2CCydPVf1MOQWBOM%2C_&vet=1&usg=AI4_-kTaUVAuBCjXct8YZyiCqs_46z2bOQ&sa=X&ved=2ahUKEwiC9e-Cq_bhAhULjVkKHbREC0EQ9QEwCHoECAkQBA#imgrc=wmV_2HoRpTpjlM:
Click to expand...

They fit a little looser but they aren't coming out of the channel. Go test fit one and see. I think I saw where CJ Hendrickson recommended this once so it must be legit. I flew my L3 that way (M1500 in a 4 inch rocket). I think 1515s look too big on a 4 inch rocket.
 
Just be sure and check the fit when using 1010 buttons in 1515 rails.
There are 3 sizes 1010 that I know of, standard-aero- small.
Only the standard I have used fit, the others will fall out when wiggled!
Also after several high thrust flights, there can be substantial wear on buttons. I either flip them over or replace as the 2 edges inside rail get worn flat. Especially with dirty rails!
 
Time for a update:
The fins have arrived, the rest of the rocket has not even shipped from Madcow. I am a bit disappointed because I ordered it about a month ago. Hopefully I can get it in time to build for High Skies in July. and launch it there. I picked up some 1515 airfoil rail buttons from Apogee Components, and they look massive. I just sent an email to the club asking what the longest 1010 rail they have is. I will be picking up the motor and casing at MHM in June and launching a minimum diameter 38mm rocket on a J530 as well as the VTS-6 I am working on painting at the moment.
 
Okay peeps, update time.

I wrote a sternly worded email to Michael from Madcow about the lateness of my rocket and he told me that there was an issue with the slotting file again. They seem to be having countless problems with slotting for these fins, so I told him to just make six slots at 10" long. I will use my dremel and a cutting wheel to extend the slots and I will use a piece of aluminium angle to make sure that the slots are straight. The slots for the main fins will be in two part so the tube doesn't collapse on itself. At the halfway mark I will leave a 2" section un-slotted to support it during construction. Once complete the structure of the motor mount will help a lot with rigidity. I have purchased the motor, casing, harnesses and parachute protectors. I got two 30 foot long, 3 loop 7/16" Kevlar harnesses from OneBadHawk for the recovery.

Hopefully I actually get my kit this time. I am getting really annoyed with Madcow not telling me when there is an issue and instead just waiting for me to call and find out what the issue is.
 
Last edited:
Your design looks very nice. Kind of reminds me of a Dynacom kit from the past. Don't understand what would be the hold up on it. Like you said you can always extend fin slots if that is the hold up. Good luck on the flight.
 
crossfire said:
Your design looks very nice. Kind of reminds me of a Dynacom kit from the past. Don't understand what would be the hold up on it. Like you said you can always extend fin slots if that is the hold up. Good luck on the flight.
Click to expand...
Thanks man! A Crossfire was my 3rd rocket. Got it with the Estes launch pad when I was 7. Good times.
 
mperegrinefalcon said:
Once complete the structure of the motor mount will help a lot with rigidity.
Click to expand...
More than a lot. Restoring the integrity of the tube would be accomplished just by having the slots filled by plywood glued in place. Not that the MMT and fillets won't stiffen it even more.

One can hardly blame you for being annoyed. If I find myself in your position, i.e. ordering a custom kit, I'll think twice about using Madcow.
 
jqavins said:
More than a lot. Restoring the integrity of the tube would be accomplished just by having the slots filled by plywood glued in place. Not that the MMT and fillets won't stiffen it even more.

One can hardly blame you for being annoyed. If I find myself in your position, i.e. ordering a custom kit, I'll think twice about using Madcow.
Click to expand...
Just make sure your slotting isn't too long and minimun .5" from the base and you should be okay ordering components from the website. I have ordered custom things before and they have been great and arrived in a timely manner. Custom work does take longer to fulfill than shipping out a kit. When the design needs more than 4 slots or has abnormally long long slots it tends to cause problems for them. I understand the issues they are having, I am just annoyed about the lack of communication to me about issues.
 
I just go the tracking info for this rocket and Michael Klet just called me to let me know it will ship today or tomorrow.
 
Time for the first build update.

I slotted the tube for everything first. I used a dremel with a carbide cutting wheel to cut the slots out. I used a piece of angled aluminum for my straight edge to mark everything.
slotting 2.jpg
Slotting.jpg

The tube seems to be holding up to these long slots very well. There was no need to worry about the length of the slots.

Nosecone coupler is epoxied inside. The metal tip is off until I paint and finish the nosecone.
Nosecone.jpg

The first two centering rings are on the motor mount.
Centering rings.jpg

The fillets here have been sanded and are not absolutely perfectly smooth, but they will certainly be strong enough. The underside of the lower centering ring does not have a fillet to facilitate the fin tabs. The fillets on the underside of the upper centering sagged more than I would have liked, but it is not really an issue. I should have waited a little longer for the epoxy to firm up.

I have a decision to make here. I can either use a 1/4" forged eyebolt that will fit through a hole I drilled in the upper centering ring, or I can wrap some kevlar around the motor tube and epoxy it in place. For the eyebolt I will have to find a nut that will either fit against the airframe as the ones I have do not, or just embed the eyebolts threads in epoxy to hold it in place. I have some 1/2" kevlar I can wrap around the body of the motor mount and epoxy to the eyebolt to reinforce it's mounting if it needs it. I know epoxying kevlar directly to the motor mount works, I just have heard that epoxy makes kevlar brittle. I have used epoxying shock cord to the motor mount on my 2.6" Madcow Screech, but that is only a 5 lb rocket, not 30-35 lb rocket. The eyebolt also gives me the option to change out the shock cord.
Centering ring drilled.jpg Centering ring with eyebolt.jpg
 
Drill a hole on the other side, smooth the edges, and run kevlar in one and out the other. Put eyes on the kevlar as a harness. If you ever need to replace it tape the new piece to the old and pull it through the two holes for a new harness.
 
I got the eye bolt to fit with ground down nuts. It fit in the airframe, but it is too close to allow for kevlar to be attached to it. I realized this after I had epoxied the nuts on sadly, but having the eyebolt in the rocket changes nothing. I will cut the loop on it off, but that is it.
20190721_213415.jpg
20190721_221251.jpg

I am going to change gears here and not mount the shock cord to the motor mount. It is too far down in the 57" tube for me to reach to change out anyway, and I don't like epoxying kevlar to the mount. Instead I will epoxy a bulkhead into a length of coupler, similar to a piston, and epoxy that inside the body tube as my attachment point. This way I can get really good fillets on the bulkhead, and have the surface area of the 4" long coupler epoxied into the airframe, this will eliminate having to worry about getting fillets inside the AF and make getting the bulkhead level much easier. I am leaving enough room in the airframe below the bulkhead for a Loki 76/8000 case so I can use bigger motors in this rocket. This will also serve to reduce the amount of volume I need to pressurize for ejection so I don't have to use as much black powder, and allow me to reach in and easily swap out my shock cord.

This is just a sport rocket, so I am not concerned about the extra mass of this component and the permanently attached eye bolt. This was a learning
experience, ie be patient and think things through more. :mad:
 
Last edited:
Possibly glue a coupler nut to side of tube.
1. If it does not clear dremel [grind] off the high side & encapsulate it with epoxy.

2.Drill a second hole opposite the first to make a "Y" harness for recovery attachment. The Y should be just long enough to barely stick out top of airframe for shock cord attachment.
Having this Y harness will also make the fincan drop straight and centered rather than lop sided which happens when only one cord is on one side. This prevents the same side of fincan from smacking the ground every flight.
Glue the Y harness such that no glue is on it above the hole. No worries about chaffing because there can be no side movement that low in fincan.

Edit: looks like you solved your issues while I was typing.
 
Nytrunner said:
Does that Eyebolt fit in the tube? It's a bit bulky
Click to expand...

Yes it does fit in the tube.

jqavins said:
Assuming it fits, does it fit with enough space to let you change out the shock cord?
Click to expand...

No, it doesn't. The knot would block the motor from going all the way in. There is basically no room for anything other than directly attaching to the motor mount.

numbo said:
Drill a hole on the other side, smooth the edges, and run kevlar in one and out the other. Put eyes on the kevlar as a harness. If you ever need to replace it tape the new piece to the old and pull it through the two holes for a new harness.
Click to expand...

blackjack2564 said:
Possibly glue a coupler nut to side of tube.
1. If it does not clear dremel [grind] off the high side & encapsulate it with epoxy.

2.Drill a second hole opposite the first to make a "Y" harness for recovery attachment. The Y should be just long enough to barely stick out top of airframe for shock cord attachment.
Having this Y harness will also make the fincan drop straight and centered rather than lop sided which happens when only one cord is on one side. This prevents the same side of fincan from smacking the ground every flight.
Glue the Y harness such that no glue is on it above the hole. No worries about chaffing because there can be no side movement that low in fincan.

Edit: looks like you solved your issues while I was typing.
Click to expand...

I could do a Y harness, and that was my first thought, but I want to be able to easily replace the shock cord, so I think the bulkhead epoxied to a coupler, then use that to make positioning in the air frame easier and give more surface area for the epoxy. The tube is 57.5" long and my fat arms won't fit down far enough to reach the motor mount.
 
Or just put an eye in the top of the motor. Air-popped popcorn is a great filler for extra space; biodegradable and keeps chutes from moving around during acceleration when using shorter motors, etc.
 
Is your Airframe Tube 4" diameter, SCH 20 PVC and the Motor Mount is Fiberglass ?

Dave F.

slotting-2-jpg.389052


slotting-jpg.389053
 
mperegrinefalcon said:
Time for the first build update.

I slotted the tube for everything first. I used a dremel with a carbide cutting wheel to cut the slots out. I used a piece of angled aluminum for my straight edge to mark everything.
View attachment 389052
View attachment 389053

The tube seems to be holding up to these long slots very well. There was no need to worry about the length of the slots.

Nosecone coupler is epoxied inside. The metal tip is off until I paint and finish the nosecone.
View attachment 389054

The first two centering rings are on the motor mount.
View attachment 389055

The fillets here have been sanded and are not absolutely perfectly smooth, but they will certainly be strong enough. The underside of the lower centering ring does not have a fillet to facilitate the fin tabs. The fillets on the underside of the upper centering sagged more than I would have liked, but it is not really an issue. I should have waited a little longer for the epoxy to firm up.

I have a decision to make here. I can either use a 1/4" forged eyebolt that will fit through a hole I drilled in the upper centering ring, or I can wrap some kevlar around the motor tube and epoxy it in place. For the eyebolt I will have to find a nut that will either fit against the airframe as the ones I have do not, or just embed the eyebolts threads in epoxy to hold it in place. I have some 1/2" kevlar I can wrap around the body of the motor mount and epoxy to the eyebolt to reinforce it's mounting if it needs it. I know epoxying kevlar directly to the motor mount works, I just have heard that epoxy makes kevlar brittle. I have used epoxying shock cord to the motor mount on my 2.6" Madcow Screech, but that is only a 5 lb rocket, not 30-35 lb rocket. The eyebolt also gives me the option to change out the shock cord.
View attachment 389056 View attachment 389057
Click to expand...
Sorry for being late to the party but I feel the need to throw in my 2 cents as far as slotting FWFG tubes goes. The nature of the beast means they are under some serious tension/compression as manufactured so the less you cut, the better off you are as far as relieving said, not even taking into account the fact that you are, like it or not, cutting structural fibers. Just look at the tube shape you end up with after slotting. Obviously you can regain some of that strength when installing fins but good luck regaining shape. For long fin spans I'd suggest multiple smaller slots with corresponding notches in the fins. Just my opinion...
 
Wallace said:
Sorry for being late to the party but I feel the need to throw in my 2 cents as far as slotting FWFG tubes goes. The nature of the beast means they are under some serious tension/compression as manufactured so the less you cut, the better off you are as far as relieving said, not even taking into account the fact that you are, like it or not, cutting structural fibers. Just look at the tube shape you end up with after slotting. Obviously you can regain some of that strength when installing fins but good luck regaining shape. For long fin spans I'd suggest multiple smaller slots with corresponding notches in the fins. Just my opinion...
Click to expand...

Yeah, I agree. I wouldn't do any longer than this. After the fins are in and the internal fillets done I will foam the fincan. This should help with tube rigidity.
 
Last edited:
Just thinking out loud, I have some 1" kevlar strap. I might just use that to create a Y harness. I will probably retire this rocket before it wears out, or I can just add that bulkhead in later. I epoxied kevlar for my 4" madcow frenzy and it is incredibly strong, though it is still an unfinished project and not launched yet.
 
numbo said:
Or just put an eye in the top of the motor. Air-popped popcorn is a great filler for extra space; biodegradable and keeps chutes from moving around during acceleration when using shorter motors, etc.
Click to expand...

High quality eye bolt in the top of the motor!!! Easy to inspect, install and change the shock cord. Interesting idea, Using shorter motors;)
 

Similar threads

B
Question on allowable reuse of parts for an L3 Cert Rocket
Replies
17
Views
914
Handeman
Handeman
Jeff Curtis
First HPR Build
Replies
11
Views
804
FlyBy01
FlyBy01
J
(Slow Build) L3 The AGM Special
2
Replies
31
Views
2K
jfcote
J
diyaerospace
David - 3" Flying Case to 60,000 ft
2
Replies
44
Views
3K
Burner
Burner
G
GaryDean L3 Build Thread - Prometheus 6
2 3
Replies
64
Views
4K
86mustang408w
86mustang408w

Latest posts

Back
Top