# King Viper IV - for discussion. Or maybe it's a 4-54SS?

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#### 75Grandville

##### Well-Known Member
I was looking at the design for a King Viper III, and I started wondering whether it was possible to build a King Viper IV - four motor tubes instead of three. Rather like a 4-29SS. Just bigger.

Now, research leads me to the conclusion that four 54mm tubes will not fit inside a 5.38" tube. A little geometry comes up with a diameter of 5.40" for the four tubes - just a hair too big.

But, if I run couplers from the motor tubes into the 5.38" body tube, that should fit.

Other than needing to respect the fact it's made out of cardboard and plywood when I do motor selection, can anyone come up with reasons this wouldn't work?

.ork file attached, for your amusement. View attachment LOC King Viper IV.ork

#### dhbarr

##### Amateur Professional
I was looking at the design for a King Viper III, and I started wondering whether it was possible to build a King Viper IV - four motor tubes instead of three. Rather like a 4-29SS. Just bigger.

Now, research leads me to the conclusion that four 54mm tubes will not fit inside a 5.38" tube. A little geometry comes up with a diameter of 5.40" for the four tubes - just a hair too big.

But, if I run couplers from the motor tubes into the 5.38" body tube, that should fit.

Other than needing to respect the fact it's made out of cardboard and plywood when I do motor selection, can anyone come up with reasons this wouldn't work?

.ork file attached, for your amusement. View attachment 306682
This is the way Flis does 7*18mm in BT70

#### 75Grandville

##### Well-Known Member
This is the way Flis does 7*18mm in BT70
That's what gave me the idea!

#### cavecentral

##### Well-Known Member
That or if removing the glassine layer buys you enough room.

#### markkoelsch

##### Well-Known Member
What if you used thin wall fiberglass tubes for the motor mounts? Thinner, not too heavy, and thinner.

#### sharkbait

##### Well-Known Member
Thinwall FWFG will fit it's 2.23 OD compared to Loc's 2.26 OD

If you want to keep it all natural though, what Kevin said will work also, peel the glassine layer off and the Loc tubes will fit. I did this in order to stuff five 24mm MMT's in my BMC School Rocket.

#### 75Grandville

##### Well-Known Member
What if you used thin wall fiberglass tubes for the motor mounts? Thinner, not too heavy, and thinner.
It would work, and it would be cool, but I think it's more spendy than I want to go. Paper MMT tubes are $8 from LOC, whereas a 36" TW tube is$47 from MadCow. Multiply x 4 and that's $156 extra. OK, I already have four 54mm paper tubes, so it's really$188 extra at this point.

Maybe if I had caught their Black Friday sale. Hmm... If I cut two 60" tubes in half and shortened the rocket by 6" that would get the price down to \$156. Two in black, two in florescent green.

Hmmm...

That's what I love about TRF. So many other people willing to share ideas!

#### 75Grandville

##### Well-Known Member
Thinwall FWFG will fit it's 2.23 OD compared to Loc's 2.26 OD

If you want to keep it all natural though, what Kevin said will work also, peel the glassine layer off and the Loc tubes will fit. I did this in order to stuff five 24mm MMT's in my BMC School Rocket.
I was thinking about something like that. Actually, my thoughts were more along the lines of using an orbital sander to take off .02" from the top of the four tubes. Then I started getting worried about structural integrity. Of course, if I cut the glassine layer off the top 6" (or sanded) and added 6" of coupler inside to strengthen it.

Hmmm.....

#### rharshberger

##### Well-Known Member
I was thinking about something like that. Actually, my thoughts were more along the lines of using an orbital sander to take off .02" from the top of the four tubes. Then I started getting worried about structural integrity. Of course, if I cut the glassine layer off the top 6" (or sanded) and added 6" of coupler inside to strengthen it.

Hmmm.....
Now theres a plan I like.

#### sharkbait

##### Well-Known Member
I was thinking about something like that. Actually, my thoughts were more along the lines of using an orbital sander to take off .02" from the top of the four tubes. Then I started getting worried about structural integrity. Of course, if I cut the glassine layer off the top 6" (or sanded) and added 6" of coupler inside to strengthen it.

Hmmm.....
You can't put a centering ring in, but I glued in smal wedge pieces in around the perimeter and a hypocycloid piece in the center, little bit of exoanding foam on top of that and you're good to go..

#### JoeG

##### Well-Known Member
Or...you could peel one layer out of the bottom inside of the larger tube.