Monday, January 15, 2018

Oil and Fuel rail spacer

I guess the old hobbs meter oil pressure activated switch used to be smaller in diameter. The ones that I could find from Vans and on Aircraft spruce do not have enough clearance to be installed into the suggested location from Vans on the firewall. I was going to go with the showplanes engine mount switch bracket, but that adds another hose under your firewall. I ended up creating a couple of spacers for the standard rail. I was going to just fabricate an entirely new rail, but the only 6061 I had on the shelf that would have worked for this task was 6" x 1" which just seemed like a lot of work.

I made two 1/4" spacers which I will add some lightening slots into at some point when I find out how much I need to space the rail out.

Door epoxy voids

I feel like I was pretty careful (really careful) during my door skin bonding sessions. As careful as you can be, there are still some spots that are pretty hard to get a clamp on. And while I was so focused on the door perimeter, I did have a couple of voids in both the perimeter as well as the lock mechanism area. 

This was nothing that a little flox, epoxy, and some syringes from mcmaster could not fix. If I were to do the doors again I would be careful about the following things:

1) While this is in the instructions. Be extra careful that the cabin top flange is has the required 1/4 clearance from the door. I did end up with a small spot on the top side of the passenger door that I missed noticing that the door was resting on the cabin top flange. Not a big deal, but I think it did pull my door out of alignment a bit.

2) I left a fair amount of material outside of the scribe line around the perimeter of the door. In retro-spec I would have cut this back to the smaller distance so that I could see a little more of what was going.

3) Some of these things would be hard to clamp up, but areas like the door lock area could use some extra attention.

4) There is no need to over epoxy the parabeam. The result of this is a bit of a mess in a hard to clean up area that really needs to be cleaned up in order to not interfere with the door latching rods.

Nose fork tow-bar blocks

My mill is in the basement (heated) so I saved a lot of the small milling projects for the winter and this was a good day to start taking care of some of those things. Not that this was a hard project (nor does it require the mill) there was no reason not to have fun while fabricating.

I started by facing the blocks that were sent along from Vans.

I don't have a DRO on my mill (not yet) so Dykem and layout it was. I used a spotting bit to locate and start the 3/8" through hole.

You guessed it. I drilled a hole in the block. I did almost make a mistake here. I was about to counter-bore the hole to make it look a little more polished, but then I realized it is the actual bolt shoulder that the tow-bar (push-bar) is going to be attached to. 

After the through hole was in, I milled a set of parallel blocks to set the angles for the next four cuts. Complete.

MT Prop Governor

Not much to see here, other than my prop governor stud length... I installed the MT prop governor that I bought off of Todd. I have to do some digging to check on the length of the prop governor studs that came on my Thunderbolt. I know people typically have to install longer studs here, but I really feel like I would like to shorten mine up a bit. The gears lines up just fine, and there are threads a couple of threads into the governor flange so there is no need for my washer stack to be on there but I had other things that I wanted to get done today without rabbit holing into a broken stud. So I loosely installed this for the time being and will come back to address it later. I probably should have left it off, but I am in the mode of getting things out of boxes and onto the plane so I can clean up my inventory a bit.

Speaking of cleaning up the inventory, I ordered a top mount governor cable bracket with my show planes cowling. This lined up just as advertised. I did have to remove the fuel injector line to route it through the bracket, but other than that, everything looks great.

Saturday, December 30, 2017

Brake and Fuel Line brackets

With the addition of braided stainless pressed fitting lines, the under seat hose management needs to be slightly modified. The original design calls for installing grommets prior to flaring the ends of the cut brake and fuel lines.

I originally had 3d printed some brackets for holding the hoses in place. I wasn't happy with the nylon print material and stepped it up to metal. I ended up using 3/4" by 3/4" 6160 1/16" aluminum and picked up the original 2 holes from the floor angle. I then put a couple #12 holes in for Adel clamps.


I then riveted the fabricated angles to the floor with 2 LP4-3 rivets and bolted two adel clamps to hold the fuel and brake lines in place.

MTV-12-B Spinner

I was making a spinner template last night so that I could start fitting my cowling. I didn't really think about it last night, but as I was laying out the board I had an issue with fitment. (don't mind the non-concentric circles, in the quasi-center of those dots are the real layout points)

The issue I had is that I started with the outer circle (15").

Thinking that I was just mis-remembering the spinner diameter I grabbed the spinner and laid out another line.

That went fine and everything bolted right up to where it should have been. But something still did not feel right. I went over to the show planes website and low and behold, the cowling is designed for a 15" spinner. So that is a bummer. I am not sure where the mix up was, but I think it all started with me assuming that all MTV-12-B spinners were 15".

I guess I have my first parts mix-up.

MTV-12-B Dimensions

One of the weekend tasks is creating a jig for the cowl fit up to take the place of the prop and spinner. I read a while back on the reliable internet that the distance between the spinner plate and the hub flange was 40mm. I did not want fit my cowling based on some internet numbers so I waited for my prop to arrive so I could take the measurements myself.

The first measurement I made was to the aft spinner cap. This looked to be 1.9". At this point I was completely assuming that the spinner itself was going to end flush with the aft plate.

Going to the manual, you will see that this is not a good assumption. When you fit the spinner onto the assembly you see that the spinner extends beyond the aft plate. With the spinner installed, there is ~1.55" between the aft most part of the hub flange and the spinner. I would really like all these numbers to add up, but having triple checked my setup, 1.54" (39mm) is the number.