Sunday, September 21, 2008


The topics of today's post: A visit to a builder; building a drill press bench; and progress on our center wing spar pieces.

Builder Visit - One day last week while sitting on-call Todd took a trip to visit a another Prowler builder. He went to see Ray who is building one of George's original kits and lives near Thousand Oaks, CA. Ray has been working on his airplane on-and-off for some time now, but the quality of the work is astounding. His precision and attention to every detail is producing the best Prowler we've seen so far. Here is a pic of his airplane fuselage in one of his garages:
The airplane is actually much closer to completion than it looks here. This is because most of the rest of the airplane parts and systems have been completed, fitted, removed from the plane for painting and then stored in one of his many shelves of boxes. He is hoping to finish the re-assembly of all the components to the airplane and have it out of the jig within the next year.

Ray has been already been a wealth of information about this airplane and provided us with much more insight about the aircraft. After talking with him, we found out that another builder has flown his Prowler. Chuck is also a builder of one of George's original kits and is in the San Francisco Bay area. We look forward to getting together with Ray again many more times. Great work Ray!

Center Wing Spar Progress - Now that Dave has a sub-kit to keep him busy in his shop, Todd has had some time to work a little more on the wing in his. If you look back in the posts, it been almost a year since we cut out the pieces for the center wing spar. Hard to believe that this much time has gone by, but now we're making more progress. After cutting with a metal band saw, the edges of all the spar pieces are left with a fairly jagged edge, so they needed to be trimmed up. Here's a pic from last year's post: Also, the pieces were scribed to the pattern and then cut just outside of the scribe lines. This leaves enough material to file down the edges to a smooth finish. Turns out this represents a lot of filing. So, on to a better way.

Sometime after cutting out the spar pieces last year, we mounted a router under one of our building tables and fitted it with a 3 blade, carbide tipped router bit with roller bearing on the end. This provides for a technique to clean up the edges of our spar pieces (raw stock) and make them match the patterns exactly.
Here's how it works:
1) Mount the router and put it in the straight cutting bit;

2) Cut two 1/4" spacer strips for each pattern. One spacer strip goes under the entire stack and provides room to have a counter-sunk bolt head. The other is to provide room between the roller bearing (that rides on the pattern) and the actual cutting part of the bit . This keeps the pattern a good distance from the cutting edges and prevents chewing up he pattern. See pic in item 4 below.
3) Drill selected holes into the raw stock using the pattern/drill guide:
4) bolt the "stack" together and adjust the router depth to get the correct height for the pattern to ride on the roller-bearing: 5) Make a ba-zillion tiny bits of aluminum foil and end up with the whole stack looking like this:
The next item to work on are the bearing blocks. They are rectangular blocks that surround the bearing and are clamped under the wing attach brackets.

Drill Press Bench - A small side project that needed to be done was to create a long bench with a drill press attached for drilling the numerous holes that must be drilled into each wing spar piece. A long bench is need to provide support for these floppy pieces of stock while being drilled. This was the solution we came up with:
By mounting the drill deck (table) under the bench top the drill can just penetrate into the bench top and (most importantly) the head of the drill press is now height adjustable above the bench top buy loosening the drill deck handle and adjusting it.
Make sure to square the head of the drill press to the bench top. We used a tri-square and make adjustments (shims if necessary) to get the press square to the bench top in both directions. It has worked great.
Another side project that is getting more and more necessary is a hardware/parts bin rack. We found an old bread rack dolly for $10 and have begun modifying it for parts bins.

Contacts - Todd and Bryan were supposed to go up to Seattle to meet with Steve who has the 4th flying Prowler this weekend. Unfortunately, scheduling issue came up and we weren't able to coordinate. We are going to try to resked the visit for sometime in Oct.

Thanks for checking in on us.

Wednesday, September 10, 2008


Welcome! Or, if you're keeping tabs on us, Welcome Back!

Well, we're managing to get another update done - and it's only been weeks, not months! But, that's because things are happening! Here goes:

Inventory & Parts List - It's taken several months to complete, but we now have a fairly accurate and fairly complete inventory of all the "stuff" we got from George. We have organized this information into a set of Parts List spreadsheets for the airplane. We now have one comprehensive document that contains information about each and every part of the airplane, what its name is, what it's pattern or template is, what it's material specification is, etc., etc. There will be changes, additions and subtractions to this set of documents as we progress, but it is a baseline to start from. Amazingly, this had never been done before, and until now all this information was scattered about in various places - or just didn't exist.

One of the biggest challenges was going through all of the old documentation and finding items that were represented as one part, but were actually made from several different parts and pre-assembled. For example, there is a short shaft that the gear are mounted to. It is "anchored" in the torque box and protrudes through the wing spar. In the old documentation, this was represented as one item. It is actually made from 8 different pieces of raw stock. For production, this information is important to know because it will affect material ordering, etc. Now we will be able to tell exactly how much 4130 (0.063) sheet steel is required for one airplane, for example.

During this process, we also accomplished two additional tasks: 1) matched up any left-over inventory with the patterns that they came from; and 2) divided all the inventory, parts, patterns etc. into seperate boxes (for now) for quick reference. So, we now also have a fairly accturate list of inventory we got from George in the sale and now know where to find it!
Vertical Stabilizer Sub-Kit - Armed with the new spreadsheets, we now have an idea of what inventory items currently exists in each sub-kit and what we will need to fabricate to complete an airplane. The first sub-kit on the list was the vertical stabilizer. Turns out that we had all but about 4 parts we needed to pre-assemble this sub-kit. As mentioned in the website, Todd is the "Production Guy" and Dave is the "Assembly Guy." The vert stab sub-kit has been produced and is now in final assembly. Dave will be doing a major over-haul on the assembly manual as he completes each sub-kit. So, in the end we will have a completely revamped builder's assembly manual.
The parts which needed fabrication included the vert stab skin, a mid-rib, a forward spar and a small angle clip. We used a vacuum bagging technique to fold and crease the skin, a break for the spar parts and the old fashioned "bang it out" technique for the mid-rib.

George came out to help get us started and guide us through the "jigging" process the first time.
Once that was done we drilled the skin and built a crate to ship it to the "Assembly Guy" - Ah, I mean Dave. Now it's on to the fabricatiion and pre-assembly of the horizontal Stabilizer sub-kit next.

Materials For the Plane - Over the past several weeks we have been sifting through the newly created spreadsheets and determining materials that need to be ordered to complete the first two groups of sub-kits. This material has been amassed and is now holding down a bench in the production shop.
This is the steel sheets, steel tubing, bearings, hardware, etc., needed to assemble the Tail Group Sub-Kits and the Wing Group 1 Sub-kits. Hard to believe, or maybe not, that including shipping this pile of stuff represents over $1K worth of materials. In some cases there is enough material to make more than 1 airplane, but some things have to be bought in a minimum order - so that's what ya get.

Contacts - We have contacted a few gents recently that are currently building, or have built a Prowler. In fact, we are going to visit Ray in the Thousand Oaks, CA area to see his project tomorrow (Sunday, Sept 14th). We can't wait, as he sounds like a really nice fellow. We have been very encouraged by some of the information Ray has given us with reference to the airplane, and several folks he's been involved with for the past (nearly) 20 years who know the Prowler and have information about it. We're sure we'll have a lot of info to put into a blog post after meeting with him. Much more to follow.
Also, as mentioned in an earlier post, we have been in contact with Stephen in Seattle area who has a flying Prowler. Bryan and Todd are going to visit with him on the weekend of Sept 20th. This is sure to be a major event in the process of expanding our knowledge of this airplane. Steve is an engineer in the field of airplanes and should have a lot of pertinent information to help us. Much more to follow here as well.
Thanks for stopping by. We'll try to get a post out after meeting the two fellows and tell ya what we found.