help big time 4.0 madcow kit

im building the madcow super batray, it says to join the two body tubes together w a coupler,and to use equal parts of the coupler in each side ?? well the aft end the motor mount tube takes up he whole end almost theres only a little more than an inch and a half to the foward centering ring,the motor mount tube is long and it said to glue the foward ring on 1/2 inch from end ? the coupler is 8 inches long ?? help

According to the Madcow Rocksim file, there is more than ample room between the fore end of the motor mount and the end of the booster tube (the motor mount tube being only 8" long).

yeah ,but thats not how it is in the kit ,the motor mount tube is literally an inch shorter than rear section,and it says to glue aft cr on 1/2 from end,could they of sent me the wrong mm tube ??

The two main body tubes should be 19" long. How long is the actual 38mm MMT tube? Have you glued the MMT together? Is it glued into the lower body tube? You could heat it up and try to slide it out, heat up the CR and remove it, then cut down the MMT tube and then reassemble it. If you were given the wrong parts, you could contact Mike at Madcow as well, I'm sure they would whatever is reasonable to help you.

yeah i just looked at the picture on the website, my mm that was sent with this kit is twice as ling at least ,now what

its already built ,the mm is an inch or so shorter than the body tube ,its clearly the wrong one,really annoyed, did alot of work on this,i hope they are gonna replace this

If you haven't yet connected the two airframe pieces, you could cut/Dremel out the foremost motor mount, then reach in and cut/Dremel off a healthy length of the MMT, then replace the fore centering ring with a new one far enough down so you can get the coupler inserted.

Contact Madcow and see what they say. They have great customer service.

Always test fit your parts before gluing together, but I'm sure you already know that. :wink:

the rocsim file is...shall we say a bit outdated. the motor tube in the current kits is 18" long and the nose cone is different too. when I dry fitted mine I noted the problem and adjusted the position of the forward centering ring aft to gain clearence for the coupler(left the motor tube at 18")...lemme see if I can find my updated ork file brb
rex
edit
found it please note that you may need to adjust the nose weight to match your build.

View attachment superbatray.ork

thats awesome that you did that rex , but thats a great catch,on your part ,i followed the directions,they are clearly wrong, i did dry fit as i was going, i didnt dry fit the entire kit first, they need to fix the directions,this kit is ruined now

perhaps one could drill a 1/4" hole near the Bt and use a sabersaw to cut out the centering ring, and clean up with a dremel and insert a new ring lower down. they came out with the kit in 2007 one might expect a change or two in 5 -6 years.
rex

Hard to believe Madcow would let that mistake hang around for so long. At least they could provide a coupler ring instead of a normal airframe sized ring to fix the issue.

Rex R said:

the rocsim file is...shall we say a bit outdated. the motor tube in the current kits is 18" long and the nose cone is different too. when I dry fitted mine I noted the problem and adjusted the position of the forward centering ring aft to gain clearence for the coupler(left the motor tube at 18")...lemme see if I can find my updated ork file brb
rex
edit
found it please note that you may need to adjust the nose weight to match your build.

Click to expand...

Probably just be simpler to cut the entire body tube off just below the top centering ring and then add a replacement tube down far enough to be out of the way of the coupler...could be tricky getting the centering to stay in play while the epoxy dries.

Thinking about it a bit more, you could attach the replacement centering ring to the end of the coupler and slide the whole kit and kaboodle in at the same time. Follow up with epoxy around the motor tube/centering joint.

Rocket repairs are usually way more involved than building the rocket from the outset.

this is ridiculous,its the first step ,and the mistake isnt known until almost the last step,its awesome that rex caught it,but you shouldnt have to catch a mistake and modify the directions just to make up for their mistake, im supposed to know the directions are for a mm half the size ,then gues to totally alter the directions and modify it to fix their mistake ? no way im tearing this all apart w dremels and such to fix their total mistake ,new parts,change the directions,unbelievable

calling them first thing ,they better be willing to make this right, and not by rigging it up, i followed the instructions to the letter, im supposed to have the foresight to see in advanced total direction failure,and modify,because they didnt update instructions , insane

perhaps it is because of my last hobby where there are no instructions(rc fast electric race boats) I got into the habit of dry fitting everything possible.
rex

Did you already completely assemble the fin can? Motor mount and fins installed?

Just tell them what replacement parts you need and I bet they'll do right by you.

no i stopped ,i would need a new mm ,cr's, eye bolt ,and first 4.0 section,i would be ok with that

Finding a motor tube that was one inch shorter than the body tube didn't throw up a red flag? I'm not making excuses for the instructions, but lets be realistic here. This build should not have gotten to this point before this was found out.

I cant imagine the need for 18"(??) of motor tube in this kit- 8" should suffice in my opinion. Even if you tweaked the kit to use DD(and thus longer motors) 8" still seems plenty when I take a peek at it on Rocksim-with the longer nose cone profile,etc which I just adjusted. My wife and I have built 3 Madcow Cowabungas between us and Im hopeful Mike will take care of you. Personally, it sounds like you followed their directions to the letter and IMO(!) you certainly shouldnt have to 'dremel' your way to a solution in this case. Just consider it a learning experience(dryfit,dryfit,dryfit!) and by all means be calm,polite,etc and let us know how Madcow handles it either way, because thats the 'learning experience' angle I'm interested in, ie how this gets resolved. Hopefully we all can learn from this experience, including Madcow if need be. Of course I could be wrong, if so somebody please say so but 18" of MM tube seems so over-the-top for this kit that I cant help but wonder if Im missing something.....




-Glenn
MDRA junkie

This is not a dig, it's just a suggestion...

It has been my experience that it is best to read through the entire instruction sheet before starting the build of any kit, especially if you're relatively new to any hobby. If you know what lies ahead before you start the first step, you'll catch mistakes like this. Measure twice, cut once.

The fix would have been to chop that mmt tube in half. No need to support the entire length of a motor case, just hold it in there straight.

Best suggestion has been to chop saw that tube right behind the forward c/r, then Dremel out the rear c/r, and sand out the epoxy from the rear of the a/f. Order up two new c/r's, chop the mmt tube in half, and start over. You'll want to double check your stability margin, but if you only lose an inch or so of airframe, I think you'll be OK.

+1 on above...Now, if my figures are right: lower tube 19", MMT 18", fore CR glued 1/2" from fore end of MMT. Gives you 1 1/2" from front of main tube to CR..Are you glueing the coupler into both main tubes or is this the separation point? If permanently joining the body tubes it should be fine..Yeah, it is a little short of the desired minimum(1/2 of the tube diameter) but it should be sturdy enough...

see this is my bpoint ,even if i caught the mistake,ive heard several logical sounding fixes,one to cut mm tube,another to put centering ring back several inches ,im supposed to guess which one will work ? i mean thats a bit much , i def will be even more cautious next time,ive built a good amount of kits ,and made mistakes,this is their mistake though, sure it would of been awesome to catch it,but i didnt, and even if i did ,who knows what fix i would of used

i definitely know a solution, put in the correct mm tube or alter the directions on the placement of the cr, beats dremels,detective work, mods,ect, lol

genzod said:

see this is my bpoint ,even if i caught the mistake,ive heard several logical sounding fixes,one to cut mm tube,another to put centering ring back several inches ,im supposed to guess which one will work ? i mean thats a bit much , i def will be even more cautious next time,ive built a good amount of kits ,and made mistakes,this is their mistake though, sure it would of been awesome to catch it,but i didnt, and even if i did ,who knows what fix i would of used

Click to expand...

Properly executed, any of them will work. Depends on you, the tools you have available, and how much work you're willing to put into the fix.

What are you going to do when you order up a kit that comes without an instruction sheet? A lot of kits come without instructions. With some kits, you're doing well to get a parts list.

Yeah, the manufacturer sent a too long motor tube. But they didn't epoxy a centering ring where the coupler belongs. If you had read the entire instruction sheet first, you would have known that 4 inches of coupler belongs in there, and would have known not to epoxy a centering ring in the way.

Like I said, measure twice, cut once. I might add... Plan your work, and work your plan. Failure to do so can be quite expensive, not to mention frustrating.

Best of luck with the fix.

:2: I understand how this thread started...the OP didn't even know if he had a problem or not when he originally posted.

However, once a potential problem has been identified , I would think it only fair for the OP and the vendor to discuss the issue privately to see if a resolution is possible. Personally, I would not state my expectations publically until I have at least given the vendor a chance to correct the situation. Defects happen.

If there is a defect, I would certainly not hold the builder accountable for not detecting it in time to prevent his current quandary. I build about a kit per month and I learn something new with each build. The things I learn may be obvious to most builders, but that doesn't mean that I should have known it before I knew it!

I am really pleased with Madcow...both with their products and their service. Give them a chance...and then come back and let us know how this very cool kit turns out. And remember...pictures are obligatory!

Cheers,
Michael

agree w michael,disagree w cherokee, i actually didnt glue a cr in the wrong spot,i glued it exactly were the directions stated, they did not send the wrong mm, the said to glue it in the wrong spot,had i even caught there mistake i would of then had to come up w an original plan on where to glue it ,so you are incorrect when you say i epoxyed a cr where a coupler belongs ,in reality i didnt , it said 1/2 inch down ,where i glued it,yes a complete expert l3 guy whos built a million kits may have perhaps caught it ,i didnt, as for madcow ,i havent said they were good ,bad ,or anything,i have not spoke w them ,i left a message,and am waiting to hear back, i will post what they said when they give me an answer,im sure it will be positive, shouldnt have to alter the directions and all this non sense to build a kit,yes they are advanced kits w out any instructions,i did not buy one of those ,so that point is irrelevsnt, as once im way more experienced i shall try one of those, this is a fairly simple build,w INCORRECT INSTRUCTIONS , thank you for all your help

and one possible reason for the long stuffer tube is to reduce the amount of bp needed. I did a little checking, w/ an 8" mmt you need almost 1.8g of bp to get the laundry out, with the longer tube this drops down to 1.2g. since AT only provides 1.2g of bp per 38mm reload...
rex

exactly rex,look no hard feelings w people here ,its a mistake in the directions,trust me ill ne aware next time to even check things even more thouroghly,not like i dont ,i dry fit almost the whole kit and checked alot, im sure we can resolve or if they wont do anything,ill be up for suggestions then, thanks

can you just cut the rocket below the centering ring and add a new ring below... see attached...