Friday, December 28, 2012

Happy Holidays - Closing out 2012

Hello Everyone,

Merry Christmas (a few days ago) and Happy New Year (in a couple more days).  I have a few Prowler related items to report as we close out 2012. 

There have been a couple of high points this year in getting the company prepared to someday begin limited production of kits.  But, sadly, this has all been overshadowed by the loss of our friend Chuck Westcott in June.

I just checked and, so far (as of 12/28/30), there is still only a Preliminary Report of Chuck's accident on the NTSB website. Chuck's presence in our community is sorely missed.  The finality of this loss will become reality sometime in Jan when Ray and I will help Chuck's wife (Nancy) to clear out and dispose of all the remaining stuff in his hangar at the Salinas Airport.  I will report on that after it is finished.

On the up side, the two most important accomplishments for me this year were:
1. Completing the home-brew press brake and the fabrication of the outboard wing spar channels in March.  Being able to fabricate parts with long straight bends is very important in the fabrication of many of the Prowler kit parts.
2.  Completing the modifications (and repairs) to the 100 Ton "Rib Smasher" press.  While I am still currently working on testing this press (and the pseudo-hydroforming process in general), getting this press to operate is a huge step in developing the ability to form many kit parts from tempered aluminum.

So, in this update:

1. Bud's Latest Report
2. Ray's Latest Report
3. Rib Smasher Update
4. Retaining Wall Status
5. New (Future) Project

Let's get started:

1. Bud's Latest Report -  I've had a few email or phone conversations with Bud recently.  He has been hammering away at his "gripe list" and recently said in a quick email:
After 2 1/2 months of work, the Florida Jaguar is back in the air. Did a round robin to Lakeland today; the tail-wheel functioned as it was supposed to and the engine ran like a champ.

Then a few weeks later Bud wrote:
During the engine rebuild, I had to replace both sets of tapered bearings in the PSRU (one set fell apart in my hands).  Now, at Steve Rogers suggestion, I shut down in coarse pitch.  Before start, I crack the throttle and set the prop lever to full forward. Just before T/O, I cycle the prop. This procedure seems to be working well.

There were no detectable prop vibrations until I started working on cruise and endurance settings. Once I went below 2400 rpm the vibration started and became worse with lower rpm.  My initial reaction was prop balance, so I did a dynamic balance. The max allowable reading is .14; mine was .36. After balancing, the reading was .06.

The next flight showed that the balancing job had no affect on the vibrations I was experiencing. Play in the blade rotation was normal but pulling a blade fore and aft produced quite a bit of movement. I suspected the spacers in the prop hub but someone else noticed that the entire hub was moving. I thought that I was going to have to replace the PSRU bearings again.

George said to pull the prop and tighten the large nut to put more pressure on the bearings. Also, I removed the weights installed from the dynamic balance. This decreased the vibrations, but not enough. I added a second spacer on top of the bearing and now there is no hint of vibration until I go below 2150 rpm. Since this well within operation range, I'll stop there.

The airplane begs for a military paint scheme but mine will have to stay in the primer while I save my pennies.

Bud also sent some of his first photo shots aloft:
I have been helping Bud on a few of his aircraft issues, and I know that he has working really hard to fix the gripes that he's identified. It is great to see the reliability of his airplane improving so much. He is also getting close to applying for his final experimental certificate. Great work, Bud. I hope the new year brings you a shrinking gripe list.

2. Ray's Latest Report - Ray has been methodically solving his engine issues. The biggest issue has been the fuel control. His engine uses a diaphragm operated mixture control unit (essentially a mechanical fuel/air mixture computer). With the help of a local tech, the unit was evaluated, then removed and sent to the factory for modifications/repairs. It has now been put back onto the airplane and dialed in. Here is the latest report from Ray:

I finished up cleaning up the oil mess (from previous breather leak) today and got the engine running. It runs like it should now. Tomorrow I may have it out again for Warren to give it his blessings as completed.   If you will be able to get by in the next week or so I will still have it operational.   After that it will be blocked in by the wings while I slosh them with sealer. Still on the list is the door for the block heater. I think that I’m running out of things to be done here so it’s time for the painting to start. I think that right now flying should begin by late spring after I get some recent stick time.

Today the only thing was a small leak on the oil fitting from the oil cooler to the block. The new oil line going into the prop gear box appears to drop the oil pressure by about 5psi at idle and no difference at speeds above 800 rpm, this with 140F oil temp. The big thing was the fuel control. If the fuel /air ratio checks out OK it’s finished. The throttle response is sharp open and closed, no hesitation and the engine runs smoother from the better combustion. Starting will take a few tries to figure out what it likes. So far engine temps aren’t a problem, I can’t get it to really get very warm. Water temp never got above 150F, oil never got above 140F. This was with the cooling doors fully closed and OAT 55F. I think that it should run warmer with the cowling on.

Tomorrow it’s over to Jerry's welding to put on the mounting plate for the blowoff valve that I got from Vortech. It should take care of pressure differential on the throttle plate.

There it is, straight from the source.  Looks like late spring for Ray's 1st flight.  Here is another pic from my last visit to see Ray:
Nice work, Ray.  We are all elated to see you getting so close to your first flight. 
 
3. Rib Smasher Update - Now that I've got the hydraulics working on the Rib Smasher, it's time to start testing it.  I had a few minutes recently and I  put some hardwood into the box to give the press something to "push" against. Then I slowly ran the pressure up in increments.  Since I had run the press up to 3,000 psi when I first installed the hydraulics, the next goal was 4,000psi, then 5,000psi:
 
Then, I took the pressure up to 6,000 psi: 
That is as brave as I wanted to get for now - without taking more precautions in case something goes wrong. At 6,000psi I looked everything over and could not find any leaks and the system held pressure very well.  Sweet!

This is a lot of pressure! To give you an idea how much pressure this is, here is an example. My smartphone is about 3"x4" creating a footprint that is approximately 12 sq. in. If there was 6,000psi holding this phone down to the table, that would represent a force of 72,000 lbs. Imagine trying to pick up a 36 Ton cellphone!!!!

I will try to press some test pieces up to 6Kpsi and see if I need to go higher. If I do find that I need the pressure to go higher - I will do it from a "more remote" location.

While testing, I want to try to make a part (or parts) that I can use down the road. The first part that I selected is a bulkhead part that is under the cockpit floor just behind the main spar, shown here:
I chose this part to start with since it has straight sides and needs to have a lightening hole fabricated into it. This will give me an opportunity to figure out the best way to form the lightening holes and see how the radius works out on bending the 3/4" flanges of the part. The first step was to go to my folders of CAD drawings and find the drawing for this part.  Then, I used that to create a CAD drawing for the die that will make this part. Here is what that looks like:
Next, I made a 3D version of what the die will look like. I included the pocket that will help to form the flange on the lightening hole and the 4 small holes that will use pins to help hold the blank in place over the die during the forming process. You can see that here:
The most critical aspect of the dies that I will have to cut is the radius that the 2024-T3 blanks will be formed over. On a cross-section view you can see that here:
If the radius on the upper right hand corner is too sharp, the metal will crack instead of form around the radius. I am starting with a 0.125" radius (a 1/4" drill bit will fit nicely into the corner of the formed part). If I get too much cracking, I will have to go back and open that radius up to maybe 3/16" and try it again. Time will tell.  Also, as I have mentioned in previous posts, you can see the sides of the die are under-cut by 10 degrees.  This is to account for spring-back of the metal while forming the flanges on the parts.

I have to have rubber to put on top of the blank to form the parts using this process. Over the summer, I frequently stopped by my local tire store and checked the dumpster for tire inner tubes. I found 4 large tractor tires that I collected in a pile on the shop floor:
I recently cut these tubes up into smaller pieces, here:
I cut the inner tubes into roughly 12" x 14" squares. These will be piled directly on top of the aluminum blanks in the press. Then a large square of 1-1/2" thick rubber pad will be placed on top of that. I still have to make or find that rubber pad. I hope to cut my first test die and press my 1st test part sometime in early Jan. More on that later.

4. Retaining Wall Status - Before the weather turned completely sour and made it impossible to pour concrete, I was able to pour the last cap pieces on the 1st phase of the retaining wall behind the shop. Here is a picture of the major portion of the wall:
Here are a couple of the small corner pieces:

That's it for this project until sometime next spring.  Once the temps start to go up and the ground dries out I'll get out there and try to finish up this project.  Until then, I'll be in the shop trying to make Prowler parts.

5. New (Future) Project - Here is a project that I've been thinking about for a long time. The shop is out in the country and we have electric power supplied by Pacific Gas & Electric. Like most things in California, this state has turned PG&E into a means to fund more welfare programs. So, the cost of electricity is skyrocketing thanks to "Cap & Trade." In an effort to lower the power bill around here, I would like to run the high draw machines (mostly the mills and the MotionMonster) using a diesel generator. This will keep the monthly power bill out of the "Upper Tiers" of use that end up making electricity cost nearly $1/KWh.

In addition, since we do have occasional multi-day power outages (caused by a variety of factors), this unit will also serve as a back-up generator to power the entire property (house, shop, well, etc.).

I recently purchased this unit from a friend for a reasonable cost. The generator end and the control panel are in good shape, but the diesel engine needs to be replaced. More on this over the next year as I search for a replacement engine and get this beast running. Here's a pic:
Well, that's it for this update. I expect that most of 2013 will be a repetitive process of making dies, pressing wing parts and building the wing structure of the 1st "all digital" airplane.  I hope you all have a healthy and happy new year. Thanks for stopping by to check on our progress.

Tuesday, December 4, 2012

The "Rib Smasher" Lives!!!

Howdy Y'all

Welcome to our 50th blog post!  That's a small milestone for Prowler Aviation.  So is the topic of this update - getting the Rib Smasher operating.  Thanks for stopping by.

I had some time so I figured I'd do a quick update to include the accomplishments of my last trip home.  It rained most of the time that I was home, so I had no choice but to get some work done in the shop.  So, this update really only addresses the work on the hydraulics system for the "Rib Smasher."  (Pseudo Hydro-Forming Press is too wordy and just doesn't describe what it will really be doing!)

The current progress on the airplane is stalled on making the tip ribs.  When I have the tip ribs made, I can finish installing the wing spar into the jig.  To get the tip ribs fabricated, I need to have the Rib Smasher press built.  The press is mechanically complete, but still needs the hydraulic system installed that I outlined in the last update.

So, that means that the project at hand is to get hydraulics installed on the Rib Smasher.  First step is, you gotta have a plan.  In the last update I posted a hand drawing of the simplified hydraulics system.  Here is a cleaned up version of that drawing that more accurately reflects the system that I designed for the press:
In the previous version, there were two HP manifolds connected by a common hose.  I initially thought of that because I had most of the HP system already in tact from a previous application.  After further consideration, I decided that if I had to make a 2nd 3-port manifold anyway, I might as well just made a 5-port HP manifold and simplify the system.  But, then I also figured out that I could put the return valve "behind" the LP isolation valve and reduce the HP manifold by one port (ended up a 4-port manifold).  I'm glad that I did - it makes for a very clean installation.

Here are the parts of the system that I purchased from the local hydraulics shop:

That left me with with two 1/4" manifolds (one 3-port and one 4-port) to fabricate and one 3/8" HP 4-port manifold to make.  To make the 1/4" manifolds I found a piece of 3/4" steel plate laying around the shop and cut it into two pieces:

Then, I popped those into the manual mill and cleaned up the edges:

Next, used the DRO on the mill to space the port holes for them:

After that, I took them to the drill press to make the 1/4" holes connect all the ports internally.  Then used the 1/4" hole as a pilot for the 7/16" drill to enlarge the hole for tapping to the 1/4"-18tpi female pipe thread (FPT)

Here are the two manifolds with the holes drilled, but not yet tapped:

All that was left to do then was tap the holes. That's not the easiest thing to do. Pipe thread taps are tapered so, the farther the tap goes in, the harder it gets to cut the threads. That is done purposefully, as the tapered hole and the tapered fittings get very snug when put together - which is what you want when you are trying to contain 10,000 psi!   Here is one of the two 1/4" manifolds completed:

When the check valves that I bought online showed up in the mail, I could start to piece the system together to get an idea of size and spacing and how to install it all on the press.  Here is an initial assembly:
When I initially laid out this system, I had planned on double ended 1/4" MPT ends on the check valves.  When I couldn't find all 4 of the same check valves at one place online at a reasonable cost, I switched to the (brass) ones shown in the picture above.  However, they have one end FPT and the other end MPT.  So, the gaps you see is where I needed 4 double ended MPT couplings to finish the connections.  I picked those up at the hydraulics shop the next day.

With the LP side of the system taking shape, it was time to switch to the HP side and knock out the 4-port manifold there.  To cut 3/8" holes into a manifold, using a piece of 3/4 steel doesn't seem thick enough.  So, I decided to use at least a 1" thick piece.  All I could find laying around the shop was an 1-1/4" circular cut out (surplus) that I picked up on the cheap at the local steel fab place.  So, I cut it up into a 1.25" x 2" x 3.5" block:

Again, cleaned it up on the Bridgeport manual mill and then drilled the ports and tap holes:

  Then tapped the 4 holes to 3/8" FPT:
The two small holes you see in the face of the manifold are 1/4" holes that are used to bolt the manifold to the side of the press.  The small hole you see in the end above the threaded hole is a goof.  That's what you get when you're not paying attention and start to cut the hole before you check to make sure it's on the correct side.  Fortunately, I caught it before I bored the hole too deep (only about 1/16" - and it didn't ruin the part.

With this complete, the easy part of the project was over.  Now, it was time to start spilling, dripping, slopping and squirting hydraulic oil - everywhere.  Try as you may, it is impossible to work on any hydraulic system without getting oil on you, on the floor, on the machine, on your tools, and generally on everything.  If you think I'm kidding, just wait until you try your 1st project.  If you already have this experience, then you know what I mean!

Anyway, I started with assembling the HP side of the system.  I had to take apart the old system and reassemble the HP hoses, the HP manifold, the LP isolation valve, the HP/LV pump and, of course, the 100 ton ram to create the system detailed at the top of this post.  Here is a (out of focus) picture of the system installed on the press.  It is not a great pic, but you can see the major HP components:
The manifold is mounted on the side of the press at the right.  The hose going off the back (right side)of the manifold goes down to the aux port on the far side of the 100 ton ram (red).  The brass plug on the aft top port is where the HP pressure gauge will be installed.  The LP isolation valve is threaded directly into the forward top port and has the handle facing out toward the operator.  And, finally the blue HP/LV pump is threaded into the bottom port on the manifold.  The plug was installed so that I could test the HP system before moving on to plumbing the LP side of the system.  I eventually got the air out of the HP side of the system and the pump and the HP side finally tested satisfactorily.

Moving on, I began work on the LP side of the hydraulics system.  After trying several iterations on and off of the press, I found the combination of plumbing that allowed the reservoir tank, the manifolds and the check valves to all be mounted neatly on the side of the press.  Here is another not-so-good pic:
In the above pic you can see the bottom of the reservoir tank (top).  The plumbing and valve on the back (right) side is the feed from the reservoir down to the intake check valve manifold.  I had initially bought a hose for this connection, but decided to  hard plumb this connection  with 1/4" pipe fittings to save space.  This part of the system does not hold any pressure, so I could just use basic steel pipe and fittings.  The Tee's in the middle have a check valve on either side and the unconnected ports eventually got hooked-up to the manual pump.  In the foreground you can see the output manifold and the hose that takes the hydraulic fluid down to the LP isolation valve on the bottom side of the manifold.  On top of that manifold is the recirc valve and  hose that takes the fluid back to the top of the reservoir tank.

This picture shows the connection of the LP side of the system to the HP side of the system via the LP isolation valve:
In order to have room to get back in the corner to install this stuff, I had to remove the manual pump.  It attaches with the two bolt holes you see in the side of the press.

Here is a pic of the entire system.  You can see the manual pump has been re-installed with the hoses that curl and go up to the Tee connections discussed above.  Again, it's not a great pic but you get the idea:

The hardest part of assembling an installed hydraulic system is getting the air out.  When the components are hooked to a several hundred pound steel press - "burping" the system can be a little challenging.  But, I got a lot of the air out by pre-filling most of the components before assembling them.  Then the rest of the air has to be either: A.) cycled out (and into the reservoir) by recirculating the fluid with the pump; or B.) individually loosening each part and then turning, twisting, shaking or otherwise moving it to try to get the air pockets to move to the "high" side and out of the system. 

Once I did that, I was able to test the entire system and eventually got the press to hold 1,000 psi with just the manual pump alone!  See it on the gauge here:
Later, I got the HP pump to get the HP side of the system up to 2,000 psi without any leaks.  Now, I will have to continue to test to higher pressures in steps - eventually working up to full pressure.

So, this is a big step in the progress of Prowler Aviation.  If this press is capable of forming wing ribs, fuse formers, etc. (as I hope it will) - this is the last major part of the production process required to someday start making airplane parts for kits. 

There still is much to do, including:
1.  Finish pressure testing the hydraulics system to ensure it doesn't leak (up to 10,000 psi - if possible).
2.  Make sure that the press will mechanically handle the 100 tons of force created by the 10,000 psi.
3.  Chop up the several large inner tubes that I've scavenged up over the past year into pieces to be used in the press while making parts.
4.  Buy or make a heavy rubber pad to go on top of the inner tube pieces that will help distribute the pressure from the top platen (top of the box) into the inner tube pieces and then into the parts.
5.  Start cutting some test dies, test blanks, and forming test pieces to learn how to form these parts (keep the metal from cracking, etc.)

 Then, assuming the tests go well,  I can start to make the 1st parts - the tip ribs.  That will involve cutting a full sized die for both the LH and the RH tip rib.  I've discussed this some in a previous post, and I will again when I get to that point.  So, stand-by for more on this.

There will be a lots of die making.  As I begin to decorate the spar with all of the nose ribs, mid ribs, longitudinal and transverse bulkheads, etc.,  every formed part of the airplane will have to have an individual die made to use in forming the that particular part.  I don't know the exact count, but my best guess is probably about 200.

Retaining Wall Sidebar - There was one day while I was home, that was nice enough to try to get some work done on the wall.  I mentioned previously that our dirt in northern CA is like "Marshmallow Fluff" when it is wet.  Well, as I was clearing some mud so that I could remove the forms from the recently poured concrete cap pieces, I shot this short video clip:
video
This is what I have to deal with when it rains on dirt that I have disturbed.  Once it drains and packs back down over a summer, then the water runs off of it and doesn't get so sloppy.  But,  what a mess when you have to work with it like this.  Anyway, I got the forms off of the last concrete I poured and cleaned up the tarps that I used to cover the last pads that I poured.

That's all for this quick update.  Thanks for checking in.  I will attempt to get one more update done by the end of the year.