Prowler Odds-N-Ends for 2024 [Catch-up Update #3] (Jan-Jun 2024)

For this "catch-up" update I decided to group the remaining Prowler related items that I have together to share with you.  The Here's the list:

     1.  Horse Collar Work
     2.  Finishing The Wing Dies
     3.  Prowler Storage Crate
     4.  AirVenture 2024

Before I get to the list, I wanted to share a couple of pics with you of some time that I got to spend with Bryan this year.  In June this year, he was flying his Areostar around the west shuttling family members to see each other.  At one point, he had gotten all the ladies and kids together in Klamath Falls, OR.  After a day or two he decided that he needed some "guy time."  So, he called me and said, "Hey Dude, I'm coming to see you for a few days!"  Well, COOL!!  So, I drove out to KRBL early the next day to see his arrival and pick him up:

We parked his plane and headed back to the shop.  He was able to stay with me for 3 days and on the balance of day one I just showed him around my shop again and updated him on all the projects that I have going.  On the middle day we made a mid-rib die together:

It was great having someone with me in the shop who is genuinely interested in the process of fabricating one of these form blocks.  He now has an appreciation for how many hours of work is going into the "tooling up" that I am trying to get done so that I can get some parts production capability going!

On the last day, he saw a new chrome grille for my pickup truck laying up out of the way (on top of the old Hardinge CHNC Lathe) and asked what it was for.  I had gotten it to replace the grille on my truck that was showing it's age and had a bunch of the chrome de-laminating from the plastic.  So, he grabbed it down, I pulled the truck into the shop and we swapped the old one out:

The old OEM Chevy badge was looking kinda beat up, so I a few days later I ordered this cool vinyl wrap for the bow-tie (Amazon - $8) and covered it.  I looks good and covers up the stone chips and bug stains underneath!  Thanks for the motivation to get this done, Bryan!  If you hadn't said, "Let's do this!" the new grille would probably still be laying where you found it!  Anyway, thanks for the visit.  I really enjoyed the shop time together!

1.  Horse Collar Work - As previously mentioned, I had Bryce and Cabi each loan me the form blocks that they had for hammering out the forward bulkheads in the engine compartment (I refer to them as "horse collars").  I originally thought that they were different sizes.  I thought that Cabi had gotten the form blocks for making the horse collar for the original Prowler and that Bryce had gotten the set for making the part for the larger RW&B Jaguar.  Turns out, they were the same size!  So, I am not sure where the 2nd set came from, or which one is even the original.  Anyway, the reason I needed them was that Vaughn was needing one for his airplane (and wanted the smaller one).  He was getting things together to start working on his engine compartment framing and I wanted to help him get the parts together.  I got the other set from Bryce because I wanted to make at least one part for inventory.

The first step in the process is cutting a blank from 2024-O material.  These parts were formed the "old fashioned" way and will need to be heat treated to the T4 condition.  [As a side note - I am considering a way to form these with 2024-T3 and the 400 ton press.  There are compromises and trade-offs with trying to do this.  I will discuss this farther down in this post.]  The next step is to drill holes in the blank so that it can be "sandwiched" between the two halves of the forming die.  Like this:

Then, you start to hammer the flanges with a nylon or hard rubber hammer.  This will cause the edges to get wavy.  So, you have to remove the blank and hand shrink the edges with a shrinker.  Then, you put the blank back into the former and hammer some more.  You do this "wash, rinse, repeat" process until the blank fits snugly to the former along the entire perimeter of the flange.  In this pic, you can see the X's that I placed on the flange.  I used this to mark where I did not want to do any more shrinking of the flange:

On the horse collars that George made for the Jaguar, the inner flange was bent up (opposite) form the outer flange.  This was to provide 1/2" more room for the front of the gearbox (so they wouldn't touch or interfere).  In these pics you see this part is formed that way:

In this pic, you can see how "snugly" that the flange sticks to the form block - this is what you want to see:

In this pic, you can see that the inner flange was formed the same direction as the outer flange.  I did this purposely for Vaughn.  He asked for his this way because he did not need the extra room for his FWF package:

Here is an example of a traditional, old school forward engine compartment bulkhead:

Here are the three that I made this spring.  One is for Vaughn, one is for Cabi, and one I have put into inventory for a future use.  Keep in mind, these are soft and still need to be heat treated to the T4 condition.  There are places around that can do this.  In the past, I found a place in LA that treated some parts for me.

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Bryce actually gave me two form blocks.  Somehow, he had gotten what I believe is the original Prowler form block for making the bulkhead that goes ahead of the horse collar and just behind the spinner.  Here it is:

From that, I made a cardboard pattern:

For now, that is all this I have done with this set of form blocks.  I might have to make one of these bulkhead for Vaughn the old fashioned way.  Or, I might be able to get the new one made and form it in the 400 ton press with 2024-T3 before Vaughn needs it.  The race is on!  Stay tuned.

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Back to the horse collars - As I mentioned above, I am trying to find a way to form these bulkheads from already tempered aluminum.  I have already started down that road - a little.  I purchased a 1" thick piece of HDPE (High Density PolyEthylene) to use to make the formers.  I wanted to try this material, instead of aluminum, as a material for the formers.  It is roughly the same cost as aluminum plate, but it can be a little easier to machine (e.g. - tools and cutters last longer and lower cutting forces on the machine/mill).

To complicate matters, I cannot form the entire part in the press at one time.  It's too big.  So, the horse collar will have to be made in two halves.  Here you can see where I have laid out the ruff outline of one half of the former:

I ordered a piece big enough to get both side from:

Here are both halves a traced out on the piece of HDPE:

That is about as far as I have gone with this project, to date.  I did do the CAD work and actually got the 3D CAM tool paths in a G-code file for my CNC mill.  Then, I realized that I'd forgotten to adjust the bend angles to account for the material springback.  So, using this set of code would make a die that would not bend the flanges correctly - and is therefore useless and needs to be redone (Both the CAD work and the CAM work!).  It is now on the "To Do List" and I am researching a better 2.5D CAM software.  More on this in future updates.

To discuss this project a little deeper, there are several pros & cons to forming this part in this manner and using this process.  Here they are:

First - the pros:
     1.  No logistics and costs of heat treating - once the part is formed it is essentially ready to put in a box and ship;
     2.  More accurate parts - as long as you get the bending angles and pressures correct, then the part will come out as designed;
     3.  Lead time - once the CAD and G-code programming is tested out, these could potentially be made in less than 2 hours and shipped the same day.

Now, the Cons:
     1.  Making the die - this part has a flange that has a continuously variable angle of bend along the flange from top to bottom.  That presents a little bit of a challenge to forming these parts correctly.  Also, if you get the angle wrong, you have the cut an entire new set of dies (at a fairly large cost of materials); 
     2.  Tabbed flange - In order to form this part in the press, the flange has to have slots cut in it (results in "tabs").  The flange edges have to shrink and there are a few ways to do this in the press - none of which is ideal;
     3.  Rigidity - Tabbed flanges result in a part that is not rigid along it's length.  For this part, the rigidity of solid flanges is necessary to support the engine compartment framing.  There is a potential fix for this that involves cutting strips of aluminum sheet to rivet the tabs to;
     4.  Additional production, additional parts/inventory - self explanatory;
     5. Additional builder work - This will add an extra steps to the building process.  While not difficult, it is additional work.  Also, there will be issues with keeping the rivets out of the way of the cam-locs and other fasteners used to secure the engine compartment panels to the compartment framing.

So, at this point, this project is on a little bit of a "back burner" while I try to finish the wing dies and aft bulkhead under the cockpit floor.  The good news here is that the aft bulkhead has a lower flange on it that is similar to the horse collar flanges - only a little simpler in that the flange is a constant angle.  I am hoping that I will learn more about the 2.5D CAM work while doing this die, and that this experience will help me finish up the horse collar formers more easily.  More to follow.

2.  Finishing The Wing Dies -  From the previous updates, you've probably seen that I have 5 center section wing and framing part dies that I have left to make.  Four of them are inter-rib bulkheads that make up the inboard fuel tanks, and one of them is the aft bulkhead under the cockpit floor that the aft wing spar and flap actuators mount to.  Here are the four fuel tank bulkheads. In this pic are the flat blank parts patterns (top), the ruff cut stock for the die (middle) and one example of each formed part (bottom):

This is another good example of why I need to make a die for each individual part.  In theory, if it were not for the need to over-bend the flanges, one of the dies should be able to make two parts - one for the right wing and the same part on the left wing (if you flipped the die over and pressed a part from that side).  But, because these parts are tapered (due to wing dihedral) and because the dies must be undercut on the sides to allow for the over-bending and springback of the flanges - a separate die must be cut for each of the parts.  Unfortunately, there is no shortcut here for me!

With these fuel tank bulkheads, I was kinda caught by surprise when I actually went to try to fabricate the first one.  Before I went to fixture the die stock, I pulled up the CAD drawing.  That's when I realized that the flanges are not bent to a 90 degree angle.  The angle is actually based on the angle that the wing skin makes relative to the main plane of the bulkhead at that location.  If I were to simply cut the stock with my normal 10 degree undercut tool - the flanges would not be formed to the correct angles!  Ooops! 

This is going to take a little thinking.  It will probably mean that I will have to shim these stock pieces on one side when I fixture them in the mill so that using either a straight end mill (or maybe my undercut tool) will give me the correct bend angle on the flanges.  It was because of this, mainly, why I decided in July that I should leave these 4 part dies and tackle them later in the year when I had more time.  That time is now upon me!

The remaining die to discuss is the after bulkhead under the cockpit floor.  I mentioned this part earlier in this update.  Here is the picture of the die stock (upper right) and the part that needs to be formed (lower left):

The "tricky" part of fabricating this die is going to be two-fold.  First, this flange is double the length of a typical rib flange (nearly 1-1/2").  That means I am going to have to laminate more aluminum onto the blank that you see above.  Second, that flange will have to be tabbed and will have to be cut in my CNC mill with a process call 2.5D machining.  To do full 3D machining, all three axes of the CNC machine must be able to move independently and in unison.  My machine will only allow the X & Y axes to move in unison - the Z axis is dependent (which means that it must be stationary anytime that the X & Y axes are moving).  The process of moving the Z axis, then move X&Y with Z stationary, then move Z again, then move X &Y is referred to as 2.5D machining.

Anyway, the point of all this is that I can still make this die in my CNC mill, it will still make a 3D part (the bulkhead die) - it just has to be done using the 2.5D process.  The new "learning curve" for me will be finding a 2.5D CAM software and learning how to use it (including getting it to run on my mill controller).  The good news here is that figuring all this out and getting it to work will make my work easier on the horse collar dies that I mentioned earlier in this update.  So, stay tuned!  You'll see more about this in a future update.

3.  Prowler Storage Crate -  As I began to get more and more of my aluminum dies made, I found myself stacking up all the old wooden dies that I got from George on a bench.  What to do with these dies now?  I will no longer need them, really.  But, at this point, I don't really want to destroy them, either - just in case I would need to refer back to them in the future.

As the title suggests, my solution was to build a crate:

What is going in this is all of the old wooden form blocks that I got from George.  I'm also putting the old steel patterns (for making the flat blanks for forming):

I tried to make this big enough that I'll also be able to stack all the old fuselage former dies in there as well - once I get those new dies cut:

Once it is filled, this crate will get set on a shelf in the lower shed.  It will all be out of the way there, yet still be available - just in case!?!?

4.  AirVenture 2024 - It was another good year, this year!  Bryan rolled into Camp Scholler on Monday before "The Monday" this year.  He wanted to log his volunteer hours the week prior to the show, so that he would have more time available during the show.  The reason for that is, he had almost his whole family in attendance this year and he wanted to be able to spend as much time with them as possible.  The timing just worked out for all of the families to use AirVenture as the excuse to hold a family reunion (of sorts).  Oh, and it was also to celebrate Bryan's 70th birthday!  I pulled my RV to Camp Scholler the following day (Tues) and this was what camp looked like before everyone else showed up:

You cannot tell from the pic above, but we got kicked out of "our corner" that we have used for the past several years.  In the past, this field was used as overflow camping and really had no "structure."  Well, all that changed this year!  Ugh!  We used to park all the way up into this corner under the trees:

Unfortunately, EAA formally "burned in" streets and put up street signs in the field this year.  Where we used to park has now become a fire lane.  So, no parking allow there any more!  The street sign you see in the pic above is pretty much right where our "yard" used to be - the area that was between our rigs in the past.  Oh well - progress!  What ya gonna do!?!?

This was one of the first planes parked in "Warbird Alley" this year.  It showed up in the middle of the week prior to the show:

One of the Honor Flights:

Two pics of Boeing Plaza on Monday:

Only the youngest two daughters were able to make it to AirVenture this year - and only on Mon-Wed.  Even though it was short, they tried to cram as much of the show in as they could.  Here is our traditional Brown Arch photo op:

Not sure, but I think this was a newbie this year.  Always my favorite airplane:

Another beautiful airplane:

These flew overhead all week.  I can't recall if these are the B-29's or the B-17's.  They were staged out of KATW and EAA was selling flights on both of them:

The F35's have been burning a lot of gas the last several years at AirVenture:

Same for the F22's:

Every year, I always say that the night airshow is worth the price of admission - even if you don't spend any of the day at AirVenture.  This year, the night airshow really leveled up!!  No kidding!  In the past, the night airshow started with the night airshow flights.  The aircraft with all the LED lighting and other special lighting and fireworks would go first.  After that, the drones would fly.  In the past, the drone shows were "Meh," at best.  Then, the fireworks would start.  The fireworks would always end with the big boom.

Well, this year definitely raised the bar on all fronts!  First off, the drone show was vastly better!  Second, there were facets of the planes, the drones and fireworks all integrated together through most of the show.  The entire show "flowed" much more seamlessly.  And, finally, the big booms and the finale were even better!  This was at the opening:

Notice the drones:

The first big booms:

The grand finale:

If and when you finally make the trip to AirVenture - make certain you include at least Wed or Sat night and catch the night airshow.  It is worth the price of admission!!

Now......for my favorite part of AirVenture 2024.  Burt Rutan and one of his best airplanes.  If you do not know who Burt Rutan is by now - you are missing out on one of the best stories of the life's work of a man who has single-handedly changed the world of experimental aviation.  From the Varieze to Spaceship One - no one, ever, has done more to "move the needle" on experimental aviation.  This year, he was flown to KOSH by the one owner of a Beech Starship (one of the few - if not only remaining flying Starship).  It is, IMHO, a really beautiful airplane:

This plane was destined to be a replacement for the Beech King Air.

Unfortunately, it was so far ahead of it's time - the project essentially was killed because of the deep paradigm of what a "business" aircraft should look like (my synopsis only and is arguable):

Burt actually gave a presentation on why the Starship did not replace the King Air (it's complicated):

This was parked near one of the campsites that passed several times this year.  Not sure if it is the real thing, or someone's reproduction of the real one - but it is really cool, and well done!

Bryan was really busy with the family this year and we did not get to enjoy AirVenture together until Sunday (the last day).  One of our rules is: One ice cream cone every day!  If you are around on the last day and know how to approach the servers, they would rather get rid of the ice cream than to haul it back off campus.  Bryan scored this year!

I was the last dog to bail this year.  This was packing up on Wed morning after the show:

Later that day, after swapping trucks:

And, here is everything "back at the ranch":

It was another great year at the "Big Show."  There are many ways to "do" AirVenture.  If you  have never been, put it on the bucket list and start planning early.  Accommodations fill up at least a year in advance, or more.  After trying many of the ways, camping at Camp Scholler still provides the best way to get minimum rest while also providing the most time to see everything that is available to see there.  It is a huge show.  You will "walk your feet off" every day and still not see everything in the one week!  That's why you have to make it a yearly endeavor!

Thanks for checking in!  See you again soon.