My Madcow 2.6 Bomarc build thread

The Rocketry Forum

Help Support The Rocketry Forum:

Wally Ferrer

SRE
TRF Supporter
Joined
Apr 20, 2019
Messages
491
Reaction score
375
Location
Manassas, VA
I don't think it will add too much weight, but I hadn't actually calculated for it, so I'm going with negligible weight.. :rolleyes:
 

Wally Ferrer

SRE
TRF Supporter
Joined
Apr 20, 2019
Messages
491
Reaction score
375
Location
Manassas, VA
Ok, I'm giving it another day before I clear coat, but I consider the build complete. I will post next whenever I manage to get it to a launch. My club is doing a members only launch this Saturday with full COVID masks and distancing. I have signed up, so I should have a final clear coated photo and one from the launchpad fairly soon.

IMG_7535.JPG
IMG_7540.JPG
IMG_7541.JPG
IMG_7542.JPG
 

AfterBurners

Well-Known Member
Joined
May 8, 2012
Messages
7,407
Reaction score
305
Location
Dallas Texas
You did a beautiful job on this build. I enjoyed watching the progress and the challenges that you faced. Thank you for sharing. After watching this it makes me want to buy one, but I'll wait until Black Friday. On the nose weight I usually use a couple coat hangers to hold the it in place. I cut two short lengths and drill the holes so they intersect and add the weight. Gives the epoxy and ballast something to stick to and not move, but I'm sure your way will work fine. Fantastic job!!!
 

Wally Ferrer

SRE
TRF Supporter
Joined
Apr 20, 2019
Messages
491
Reaction score
375
Location
Manassas, VA
I started to panic, as I contacted Ken from Performance hobbies about a motor, and due to no one flying his stock of 29mm H and I is none. He has a G76-G, which at my rocket's weight sims to just over 450 feet, just barely fast enough leaving the rail. I had to go through my own inventory, thinking I might already have a G76, and I discoverd an H180W, which was my first choice for first flight, sims to just over 1300 feet. :music1::dancingelephant::dancingelephant::music1::cheers:
 

AfterBurners

Well-Known Member
Joined
May 8, 2012
Messages
7,407
Reaction score
305
Location
Dallas Texas
I started to panic, as I contacted Ken from Performance hobbies about a motor, and due to no one flying his stock of 29mm H and I is none. He has a G76-G, which at my rocket's weight sims to just over 450 feet, just barely fast enough leaving the rail. I had to go through my own inventory, thinking I might already have a G76, and I discoverd an H180W, which was my first choice for first flight, sims to just over 1300 feet. :music1::dancingelephant::dancingelephant::music1::cheers:
Flight photos please
 

Wally Ferrer

SRE
TRF Supporter
Joined
Apr 20, 2019
Messages
491
Reaction score
375
Location
Manassas, VA
Launch day! Separation of the rocket from the chute, I think my shock cord was too short, I almost swapped it out before heading out to the launch. Lesson- trust my spider-sense in the future. Still, recovery was safw, sustainer floated down- with just a touch of trimming it would be a nice glide :rolleyes:... Nose cone landed in a nice prickly tree, but all was recovered- byt the roto-sail suffered a few burn holes, so I think I had a touch too much ejection charge. It also tore a little catching on thorns coming out of the tree.

No one was hurt, all pieces recovered, so I'll call it successful, if not ideal.


IMG_7559.JPG
IMG_7560.JPG
IMG_7563.JPG
IMG_7565.JPG
 

AfterBurners

Well-Known Member
Joined
May 8, 2012
Messages
7,407
Reaction score
305
Location
Dallas Texas
I'm not following did the shock cord break or did you have the pieces come down on separate chutes? Looks like that one chute really got torched?
 

Wally Ferrer

SRE
TRF Supporter
Joined
Apr 20, 2019
Messages
491
Reaction score
375
Location
Manassas, VA
I'm not following did the shock cord break or did you have the pieces come down on separate chutes? Looks like that one chute really got torched?
The cord broke- I'm pretty sure I had too much charge for the tube size, which I believe helped torch the chute... I used 3/4 of what came with the motor, 1/2 of what comes with it would be more appropriate for the 2.6"... I might have to start real measuring at some point. I think the combination of it being to short, a bit too powerful charge, and a heavy nose cone was too much for that nylon cord. I will be replacing it with some kevlar, and will probably triple the length.


IMG_7573.JPG
 

AfterBurners

Well-Known Member
Joined
May 8, 2012
Messages
7,407
Reaction score
305
Location
Dallas Texas
The cord broke- I'm pretty sure I had too much charge for the tube size, which I believe helped torch the chute... I used 3/4 of what came with the motor, 1/2 of what comes with it would be more appropriate for the 2.6"... I might have to start real measuring at some point. I think the combination of it being to short, a bit too powerful charge, and a heavy nose cone was too much for that nylon cord. I will be replacing it with some kevlar, and will probably triple the length.


View attachment 420400
Good solutions, but why not just have the nose and aft section come down with separate chutes? I like Madcow kits and have built plenty, but not real fond of the supplied recovery harness. Thats the first thing I change out and the flat chute that comes with the kit.
 

o1d_dude

'I battle gravity'
Joined
Jan 18, 2009
Messages
7,723
Reaction score
577
Location
Urff
Chutes can be repaired or replaced. Probably the latter based on the photos.

The important thing is the airframe and it appears intact.

How long was your shock cord?
 

Wally Ferrer

SRE
TRF Supporter
Joined
Apr 20, 2019
Messages
491
Reaction score
375
Location
Manassas, VA
I was thinking about a second chute for the nose cone, but then I would have two parts to recover, and somehow with my luck they'll drift in opposite directions. 🤣 The cord was only about six feet long. I have a 20' nylon cord, and plenty of tubular kevlar, so will probably go with a 20' piece of that. A new rotosail has already been ordered. I'm guessing my launch video file is simply too large to just upload as it just errors out. I would still like to share it, any best method for sharing video here?
 

mbeels

Yes balsa
TRF Supporter
Joined
Feb 9, 2019
Messages
1,958
Reaction score
888
I'm guessing my launch video file is simply too large to just upload as it just errors out. I would still like to share it, any best method for sharing video here?
I think that the easiest thing to do is first upload it to a video sharing website, such as youtube or vimeo, and then post the link here.
 

Wally Ferrer

SRE
TRF Supporter
Joined
Apr 20, 2019
Messages
491
Reaction score
375
Location
Manassas, VA

I'm no George Lucas... Where's my camcorder with dedicated toggle switch for zoom? Apologies for making you squint :cool:
 

o1d_dude

'I battle gravity'
Joined
Jan 18, 2009
Messages
7,723
Reaction score
577
Location
Urff
Well, you nailed the “up” part. Great boost.

A 6’ shock cord is definitely a bit short to my way of thinking. If it were my bird, I’d be looking at something around 12-15 feet long with the chute attached at about the 2/3 point (8-10’).

It’s a shame about the laundry having to be replaced but that’s simply a matter of sending money out rather than making rocket repairs.

Nice launch site but the trees make me nervous.
 

neil_w

Hunkered down and slowly going crazy
TRF Supporter
Joined
Jul 14, 2015
Messages
8,669
Reaction score
2,106
Location
Northern NJ
Glad you got it all back... final product is absolutely beautiful, first rate all the way.
 

Wally Ferrer

SRE
TRF Supporter
Joined
Apr 20, 2019
Messages
491
Reaction score
375
Location
Manassas, VA
Well, you nailed the “up” part. Great boost.

A 6’ shock cord is definitely a bit short to my way of thinking. If it were my bird, I’d be looking at something around 12-15 feet long with the chute attached at about the 2/3 point (8-10’).

It’s a shame about the laundry having to be replaced but that’s simply a matter of sending money out rather than making rocket repairs.

Nice launch site but the trees make me nervous.
The trees line a creek, with a nice pond in the other direction as well. We don't have a lot of options right outside of Washington D.C.... I have yet to lose any rockets there, but have certainly come close :music1:
 

grouch

Well-Known Member
Joined
Apr 9, 2011
Messages
3,740
Reaction score
660
Location
Phoenix AZ
FYI, I've broken more shock cords than I care to admit and each time I make the same observation and conclusion you did.....I still can't bring myself to lessen the charge. Mine have mostly happened with 38mm tubes. I'll get it sorted out one day!
 

Wally Ferrer

SRE
TRF Supporter
Joined
Apr 20, 2019
Messages
491
Reaction score
375
Location
Manassas, VA
FYI, I've broken more shock cords than I care to admit and each time I make the same observation and conclusion you did.....I still can't bring myself to lessen the charge. Mine have mostly happened with 38mm tubes. I'll get it sorted out one day!
Honesty, appreciated! :cheers:
 
Top