BT55 size Honest John sport scale build thread

[bjphoenix]

Digging in my closet from my BAR episode of 10 years ago I found an opened kit for the Estes Deep Space Transport. I don't remember where I got it and it isn't the type of rocket I like to build, and I noticed that the nose cone looks like a semi-scale HoJo nose cone, so I decided to kit bash it into an Honest John. I want something that looks like the Honest John, but I want it for launching not for entering in a scale contest, so I think it would be better called sport scale than just scale. I put on thick fins and I'm not even going to attempt to sand proper airfoil shapes into them. I don't know how much work I'll do to replicate the spin motors.

I searched the net and found some photos. I picked one, imported it into autocad and scaled it, and measured all of the critical dimensions. Then I searched some more and found the scale drawing from Peter Alway, which makes my previous work obsolete. With these dimensions, I cut out some fins, and started making the motor mount assembly. That is as far as I've gotten, but these little bits illustrate some of my build techniques.

In the attached photo you can see the motor mount tube with the motor retainer and centering rings attached and filleted. I've also attached a loop of Kevlar thread for the recovery harness. Wanting the motor retainer attached so it could resist thrust from the engine and also so it would resist ejection charges, I put it on the motor tube with epoxy. I will later glue a few wraps of paper around the engine retainer to hold it in place and keep it from pulling loose when you flex it to put the motors in/out.

Also in the photo you can see the fins stuck together with sewing pins. I line them up, pin them together, then I can sand them all to the same shape.

 

[bjphoenix]

In the past week or so I have sanded the fins, put on my rounded edges airfoils and put on a coat of Elmers FillNFinish and sanded it.

Visible in the photo is a wrap of paper over the engine retainer to hold it in place. I've seen Estes kits do this with a short length of tubing. The paper was easy for me to do, I think I did 3 full wraps.

I've built several mid-power rockets with this technique but it has been awhile, and this is the first time I've done it for a low-power rocket. I glued the fins on one at a time. Since this rocket has 4 fins I should have glued them on in pairs. I don't use a jig to align fins, I do it by eyeball, and it is easier to align fins if you have fins placed on opposite sides so you can align them against each other. The other mistake that I made was in not drawing lines on the motor mount tube before gluing on the centering rings. After putting the rings on it is difficult or impossible to draw the lines parallel to the axis of the tube. After gluing on the fins I put wood glue fillets on.

Next step will be to mark the main airframe and cut slots for the fins. After that the build will be all downhill. I like to build this way because I think it makes for very strong fin attachment, but it takes a lot of work to build the "fin can" assembly. Once this one piece is done, I glue it in the rocket and fillet the fins and I'm ready for paint.

 

[bjphoenix]

Today I slotted the airframe and glued in the fin/mount assembly.

I held the fin/mount assembly against the end of the airframe, put pencil marks on in line with each fin, and another mark to indicate where the engine hook goes. I drew 2 lines, spaced the thickness of the fin apart plus a little bit, then cut them out with a sharp blade. My slots ended up being a bit too tight so I had to trim them a bit until the fins fit easily. I taped a q-tip to the end of a pencil and put a ring of glue in the airframe just short of where the front centering ring would end up, and slid the fin assembly in. After that dries I can put a fillet on the back of the rear centering ring. I'll have to use some thin strips of tape to hold the 4 strips of airframe against the rear centering ring until after it dries, then I can put on the main outside fin fillets.

 

[mikeyd]

Nice Build

Here is where the Nose Cone originally was used.
https://www.spacemodeling.org/JimZ/est1919.htm

 

[SacEsq]

Today I slotted the airframe and glued in the fin/mount assembly.

I held the fin/mount assembly against the end of the airframe, put pencil marks on in line with each fin, and another mark to indicate where the engine hook goes. I drew 2 lines, spaced the thickness of the fin apart plus a little bit, then cut them out with a sharp blade. My slots ended up being a bit too tight so I had to trim them a bit until the fins fit easily. I taped a q-tip to the end of a pencil and put a ring of glue in the airframe just short of where the front centering ring would end up, and slid the fin assembly in. After that dries I can put a fillet on the back of the rear centering ring. I'll have to use some thin strips of tape to hold the 4 strips of airframe against the rear centering ring until after it dries, then I can put on the main outside fin fillets.

Was this, and the previous pic, a mod or was this the way the kit had it done? If a mod ... I love it! Great idea.

 

[bjphoenix]

Was this, and the previous pic, a mod or was this the way the kit had it done? If a mod ... I love it! Great idea.

No, this is my own idea. I used the nose cone, body tube, motor tube and centering rings from another kit, a kit that used normal surface mount fins. I cut my fins out of spare balsa that I had, and cut them with fin tabs in mind. This is really sort of a "kit bash", or mostly scratch built rocket.

 

[bjphoenix]

Since the last installment-
I glued in the fin/motor assembly, added fin fillets, built launch lug standoffs, and added 3 bands around the body. Between Peter Alway's drawing and photos I've seen I found different dimensions for the bands so I just picked something and went with it.

Today I had a chance to put on a coat of white primer. The primer points out a few spots on the fins that need touch-up filler.

I haven't decided on a paint scheme yet but I don't think it will be OD. I've seen photos of rockets on display that are predominantly white or red so I'm thinking about making my own version of something like that.

 

[gdjsky01]

Digging in my closet from my BAR episode of 10 years ago I found an opened kit for the Estes Deep Space Transport. I don't remember where I got it and it isn't the type of rocket I like to build, and I noticed that the nose cone looks like a semi-scale HoJo nose cone, so I decided to kit bash it into an Honest John..

just saw this. Or got round tuit. Hilarious. I am just the opposite. No interest per se in a HoJo but would love the deep space transport.

Guess all I need is a HoJo NC and the decals.

Miss my DST. One of my favs

 

[Buzzard]

Nice Build. Just for clarification, the nose cone is for the M50 version of the Honest John, a smaller version of the vernerable HJ. The fins you used are for the earlier M31 which had a similar nose cone, but the spin rocket packs for stability of the unguided rocket were external to the cone. Really doesn't matter unless you want to build a scale model.
Some of us are funny that way. BTW, I do have a Deep Space Transport kit. Plus a partially assembled Estes HJ kit from decades ago that one of my brothers gave me with all of his stuff. Been doing this since 1967....and the wife thinks I should grow up!

 

[bjphoenix]

Nice Build. Just for clarification, the nose cone is for the M50 version of the Honest John, a smaller version of the vernerable HJ. The fins you used are for the earlier M31 which had a similar nose cone, but the spin rocket packs for stability of the unguided rocket were external to the cone. Really doesn't matter unless you want to build a scale model.

At the beginning I was dubbing it a "sport scale" so I could get away with making it less than 100% scale. For instance I wanted strong fins and didn't want to try the diamond airfoils. I also was undecided about the spin motors but I'm thinking about making better representations of them. I just like the fin shape of the original HoJo better than the smaller fins on the later version.

 

[bjphoenix]

just saw this. Or got round tuit. Hilarious. I am just the opposite. No interest per se in a HoJo but would love the deep space transport.

Guess all I need is a HoJo NC and the decals.

Miss my DST. One of my favs

I could send you the remainder of the kit and you could fill in what is missing. I used the main tube, nose cone and engine mount. I think the rest of it is still there. There are a lot of pieces in that kit.