Tuesday, December 18, 2012

Huntsville Record Trials 2012

Huntsville IMBPA Record Trials November 24-25, 2012:

Martin Truex Jr        A Hydro 1/3 OVAL           19.019 sec
Martin Truex Jr        D Hydro 1/3 OVAL           16.999 sec

David Hall                B O/B Hydro SAW            2.939 sec    76.556 mph
David Hall                B O/B Hydro 1/3 OVAL   24.168 sec
David Hall                P Hydro 1/3 OVAL          19.964 sec
David Hall                S Hydro 1/3 OVAL          20.164 sec

Mark Bullard            Twin Hydro 1/3 OVAL     18.423 sec

  • A = 2.1 cc
  • B = 3.5 cc
  • C = 4.9 cc
  • D = 7.5 cc
  • E = 11 cc
  • F = 30 cc
  • N = 1.2-7.4V
  • P = 8.4-14.8V
  • Q = 15.6-22-2V
  • S = 22.8-29.6V
  • T = 33.3-37.0V
  • The 1/3 mile oval course has 100.58 m long straights
  • The radius of the corners is 10.66 m
  • Total length: 268.22 m

Truex quite fast with his 2.1 cc hydro.

Hall's record run with a JAE OB 21 hydro. Novarossi power.

Hall's record oval S-hydro run.

Truex oval record run with his Novarossi 46DD powered JAE45 - 8 second laps! :)


Wednesday, December 5, 2012

T2-21 Build-Series #6

Time for the stuffing tube, cowl-mounts and the remote needle base.

KEP's T2 .21 Presentation
KEP's T2 .21 Freebie
KEP's T2 .21 Build Series #1
KEP's T2 .21 Build Series #2
KEP's T2 .21 Build Series #3
KEP's T2 .21 "Inspirational" Article
KEP's T2 .21 Build Series #4
KEP's T2 .21 Build Series #5

BBH lightweight motor mount rails are installed with suitable spacers.

Here you can see a "dry-fit" of the stuffing tube that will be glued inside the tub and the flex tube that runs inside that. We have also made an aluminum flex adapter that is used when aligning the flex tube vs the engine flex coupling/collet. The adapter has two diameters - one that fits inside the flex collet and the other end that fits inside the K&S 1/4" flex tube.

Open up the hole through the tub bottom. Use the side view template of the tub sides as a guide where the stuffing tube will go through... Here it's dry-fitted with the flex tube installed as a reference to check that it will be straight.

Push the flex tube up and over the adapter (if you have made your own) or close to the flex collet and do a visual alignment...

Tack glue the stuffing tube with 5-minute epoxy.

Add milled fiberglass to epoxy glue and make a fillet around the stuffing tube.

Make a stuffing tube cover from some 1.5 mm plywood scrap and glue it with 5-min epoxy.

Use a mix of milled fiberglass and epoxy glue to make a filling inside the radio room where the stuffing tube meets wood. I also add the same filling under the "wedge" area under the stuffing tube tube as reinforcement.

Small pieces of 25 g fiberglass cloth is cut-out to make extra reinforcement on the inside and outside. These are "brushed" in place with laminating epoxy.

When the laminating epoxy has set the edges of the tub-bottom cloth is sanded down smooth.

The fiberglass cloth over the stuffing tube inside the radio box is done the same way. The lower tub in the picture has only the epoxy-glue & milled fiberglass mix added. The upper tub has the cloth in place.

The front cowl mounts are made from 0.7-0.8 mm thick polycarbonate ("Lexan") sheets that are cold bended. The lower one has one leg that is a bit longer. See the PDF's for more info.

Personally I use SS 4-40 screws for mounting so I drill the holes at 3mm. Note that there should be about a 1 mm gap between them as the cowl will be there... Note also that these angles will be fixed later on with smoother corners etc.

The lower cowl-mount angle is aligned so its about 1-1-5 mm below the tub deck. And the holes are marked out with a pen and the holes drilled. For 4-40 threads I use a 2 mm drill bit and then use a 4-40 tap to start a thread so to speak - then thread in the 4-40 screw.

Use one of these gadgets when drilling these holes. Don't drill too deep!

The cowl is fitted with the only the lower angle installed. Make small markings on the cowl where the edges are on the lower cowl mount.

Then the rear is fitted.

With the markings as a guide do a slot in the front of the cowl. See the above pics as reference.

Drill 4 mm holes through the cowl and the rear cowl rests in the tub. Use a drill press so the holes will be straight!

These 4x4 & 4x2 mm neodymium magnets will be glued with epoxy glue.

Dry-fitted magnets in the cowl and tub.

Sand the outside of the magnets and clean them. Make sure the magnets will be facing the right side of each other and glue them flush with 5 minute epoxy.

The protruding upper part of the magnet will be smoothed out with a mix of epoxy glue and milled fiberglass (as a putty).

Here the pipe-mount is also installed (will be a later article) and the hole/slot for the NR exhaust adapter is opened up.

The holes are drilled for the VictoSport needle base and also the pipe-mount (will be an later article). Note that you can only use 2 of 3 holes in the VictoSport needle base as the lower hole is covered by the lower banjo-nipple.

Done for now. :)

Next: KEP's T2 .21 Build Series #7

Wednesday, November 28, 2012

Gone to Abu-Dhabi

No KEP's T2-21 build-article this week as I'm in Abu-Dhabi this weekend for the second to last F1H2O World Championships race of 2012. :) The race itself is held on Thursday and Friday. Check the official site for live timing.

Link to my pics from 2 years ago when we where there. :)

Friday, November 23, 2012

T2-21 Build-Series #5

Time 2 do the switch mount, switch hole, antenna hole, bottom sheeting, nose block & transom carbon... :)

KEP's T2 .21 Presentation
KEP's T2 .21 Freebie
KEP's T2 .21 Build Series #1
KEP's T2 .21 Build Series #2
KEP's T2 .21 Build Series #3
KEP's T2 .21 "Inspirational" Article
KEP's T2 .21 Build Series #4

The receiver switch mount looks like this. Its made of scrap pieces of 6 mm gaboon plywood & 1.5 mm thick fiberglass sheet. The screws I have used are 4-40x1/4" aluminum or SS. Do the switch holes so they match your switch. The two brackets are glued with ZAP-a-gap CA glue.

Now it's time to drill the holes for the antenna tube holding-tube and receiver switch access hole in the tub-deck / tub-deck doubler.

Make sure that you have sanded the bottom of the complete tub-frame flat and smooth! Then its time to bring out the flat board again and the bar stock angles and clamps... You want to make sure that the sides are straight and square before you glue the frame to the bottom sheeting. Once it's glued to that you're stuck with what you get basically. So don't forget this step to get the tub straight and flat! :)

Cut out a preferably cross-grained 1.5 mm thick plywood sheet that is a little too big. Sand it slightly. Turn the tub-frame up-side-down and add ZAP-a-gap medium CA to the tub sides bottom from the rear and to approximately where the engine will be (= the flat part of the tub bottom) and the rear bulkheads, transom bottom edge and the bottom part of the servo mounts. Then turn it around again and align it in the center of the tub-bottom sheeting. Press down for about 1 minute.

Then you add ZAP-a-gap glue to the front part of the tub-sides and the front bulkheads (use more glue in the front part) and roll-press it down more and more to the front until the glue starts to set... Have the CA kicker nearby if you need it to get the glue to kick but don't use too much of it at this stage. If you have a friend close by that can assist it's even better! :) Let it sit for a few minutes and remove the aluminum angles.

Ps, it's a good advice to also use a fan to blow away the CA fumes while gluing!

Now apply a bead of CA glue on the inside and outside of all bottom sheet glue-joints. Let that soak in for at least 5-10 minutes. Then you can remove some of the excessive glue that hasn't set yet with house hold paper but be sure to be quick. Swipe one time only as the second time the paper will be glued to the joint... After that, spray a mist of CA kicker on all glue joints and leave it for a couple of minutes.

Use a small model-plane tool to remove most of the protruding bottom sheeting - finish it with the std 1 foot long bar-sander with 80 grit paper.

Here is some sanding tips: you know it's easy to sand too much and sand through the outer ply layer of any plywood sheeting right? Three major reasons for that to happen according to me. 1 - You don't pay attention and aren't looking to what you are actually doing... 2 - You use a bad sanding block that is not flat and too fine graded sanding paper (The worst sanding block you could ever use is the old cork-block that you just fold the sand paper over the edges! And if you use too fine of a sanding paper you need to sand more on each part and push harder = more of a chance that you sand to much or tilt the sanding block too much etc)... 3 - You sand too much, too far, too early... On a boat like this you have plenty of protruding plywood parts that need to be sanded down that "work" on the same "surface" so to speak. The trick is to sand just enough each time and when all the gluing is done do a final sanding where you can sand everything together. As an example - wait for the final sanding of the tub-sides until the deck, bottom, nose-block and carbon transom doubler is glued in place and sanded almost smooth. Then you can sand it smooth/flat. The "perfect sanding" is not done until the complete boat is done though and you start preparing for the epoxy sealing process. Get it? :)

In the earlier years we used the traditional hard-wood solid nose blocks on all riggers. But we have done them like this for the latest few years. Especially if you clear coat the tub the look is much nicer (I think). The nose block is glued together (with CA) std 8 mm birch plywood pieces but you can use some other plywood also like gaboon.

Make sure the nose piece of the tub is completely flat! Then use plenty of ZAP-a-gap CA and cover the nose of the tub completely with glue. Press down towards the nose-block until the glue sets. As you have used so much glue it will take a while for it to actually kick but don't use kicker yet. Wait until it has actually start setting and then use kicker as you want he glue to soak in good.

Use the band-saw to remove excessive nose-block material. The rest is sanded away... So make sure the bar-sander you use has a really fresh/new 80-grit sand paper glued to it as this takes some time to do.

When the rough first stage of sanding is done you need to make it smoother and more round... Take your time and do it in small steps (slowly) so to speak... Practice makes perfect... ;)

Time to add the carbon sheet to the outside of the transom also. Make the part a little to big and sand the surfaces slightly before gluing. It's also time to check that the transom actually is straight before gluing the carbon sheet... When you have fixed that use plenty of CA glue on the transom and press down on the carbon. As you use plenty of glue it can float around a bit before it kicks. When it has started to kick you can finish it off with a mist of CA kicker. CAREFULLY sand the protruding carbon edges down smooth with the plywood. Take it easy and go slow! Sand from the rear to the front only as the carbon could de-laminate if sanded the other way.

Done for now - Have a nice weekend! :)

Next: KEP's T2 .21 Build Series #6