As it turns our the previous seat that I ordered was not strong enough. It was flimsy, it looked good on the website but when we received it, I can not imagine pulling 5 g’s in that thing. While flying an aerobatic sequence, a 200 pound person would exert 1000 pounds in this seat and I do not want to risk this thing coming apart. One reason for selecting this seat was the lightweight, at 2 pounds that would be great for my overall goal of having a lightweight aerobatic competition airplane.
So I have selected another seat. Kirkey 41900V, it weighs 10 pounds but it is built like a truck, it already has the seat-belt holes built it, and it has a simple option for covering it. One last positive is that the seat is wider, that can accommodate my ever-so growing waist line!
I am very happy that we have been getting a lot of work done on the build. From the update last month, I was speaking about seat options. There was someone on the BiplaneForum that reccomend a Tillett seat, and I looked into this option, and a few others including a custom seat. Well, the Tillett seat seems to be a winner. Having side support is an important factor because when doing aerobatics, I need to stay firm in my seat for better control.
Here is the Tillett seat.
Also the previous builder fabricated the bungee truss incorrectly using the wrong size steel. The old bungee truss was cut out.
The area was sand blasted and the new bungee truss was test fitted.
And finally welded in to prefection.
I ordered riging boards from Steen Aero to check the incidence of the wings.
The top wing was test fitted just to see where we stand. So far everything is looking good.
We also had a chance to figure a location for the com and transponder antenna. The com antenna most likely will go in the turdle-deck, which has no metal surrounding it, just wood and fabric. The transponder antenna will go somewhere under the belly. Also we are giving though to harness (seatbelt) location. Metal tabs will need to be fabricated to archor the belts.
I am happy that I already purchased my ticket for Sun-n-Fun, I fly in late Monday night (actually it’s Tuesday morning and leave late Wednesday. At SnF I can accomplish a lot and get some ideas for my build. My main reason for going is to try on different manufactures of parachutes, see which one fits me the best. Also I plan to try on a helmet.
Still, I am up in-the-air (Pun intended!!) about if I want to put lights on my airplane, so this will give me the opportunity to meet different vendors and if they have something lightweight and economical, I may consider it.
My plan is to put a one-place canopy on, so again, a great opportunity to see what everyone else is doing.
It is time for me to consider what I want to do about a seat so I got a great idea from someone on biplaneforum. His method was to use a system that creates a custom mold of you bum. After the mold is finished, it is trimmed, some extra squeeze foam is added to certain areas. Then finally the mold can be covered in your choice of fabric (4th, 5th & 6th picture down). This is fantastic, the only problem with this route is I will need to have a parachute to be able to make the mold, and most likely I will wait on the parachute purchase.
Another option I have for a seat is purchasing it from Aircraft Spruce. The only problem with this is that the seat doesn’t look that comfortable. I did find someone who installed this seat and has gotten good reviews so this may work.
We are making great progress. Last month I discussed the truss that was ordered from Steen Aero. The new one arrived and we began grinding to fit it into place.
Some sheet metal tabs were grinded off to help fan out the firewall. If you remember a consistent mistake the previous builder made was not measuring to the center of the tubes. Now the airplane is about an inch smaller so everything has to be custom fit.
I am happy that much need work got done on the Skybolt this month. The previous builder made a mistake. Some mistakes can be classified as “big”, or maybe “small”. This mistake, let’s call it consistent. When measuring, a steel tube for example. You measure from the end (outside) of the tube to the center of the adjoining tube. Our previous builder measured to the outside. So as this is a mistake, the mistake is consistent and carries through to the rest of the airplane, about a half inch everywhere, about one inch total.
The engine mount was made by Steen Aero, it did not fit. This was my mistake, I assumed that everything on the airplane was to plans. I only learned of this half inch/inch mistake by incorrectly ordering the engine mount without actually measuring. Steen Aero graciously took back the engine mount. We now had to make a template and send it off to Steen Aero to build the engine mount.
Here is a photo of the engine mount template.
Engine mount template
Engine mount template
So now we must wait at least a month for the new one to be made.
Now on to the bungee cord truss.
As you can see from the plans, the bungee truss calls for 1 1/8″ tubes all around. For some reason the previous builder used 1 1/8 tubes for the top pieces, but the main tube that runs the length of the truss was made of 7/8″..?!?
The amount of work required to cut out that tube and replace it would warrant a lot of work. It is easier to replace the whole truss. The simple solution would be to order a bungee trust from Steen Aero. However the aforementioned problem of a half inch will most likely come into play. Steen Aero was kind enough to ship up a truss and if it fits we will use it as-is. But most likely, I am expecting a modification. Only time will tell.
Here is a similar bungee truss finished on a different airplane. The truss along with the bungees support the weight of the airplane and keeps the gear from collapsing. This builder did weld a gusset-type of support in the bungee truss, will it help strengthen? Perhaps a little-bit
As mentioned in the first part of the January Summary we had some issues with the new engine mount not fitting.
An engine mount jig was made and sent to Steen Aero for them to make a new engine mount.
Part of mounting the engine mount to the frame requires a ‘engine spool’ to be welded into the frame.
Here are the spools and where they need to be welded. Some of the diagonal tube needs to be cut for a nice fit.
Because I am building this airplane strictly for aerobatics, I am trying to save weight everyplace I can. My firewall was built out of titanium to save a few pounds.
Here is the new firewall:
We also closed up the longerons with steel plates. The edges were made chamfered so when/if the edges need to be grinded, it wont compromise the integrity of the weld.
Now onto the wing attachments. If you take a look at the plans the front wing fittings require the tab (flying wire attach point) to be bent to 26.45 degrees. The previous builder who I purchased the airplane from welded this tab on instead of bending it.
Here is a picture from another builder that has encountered the same problem as me.
This is not good, especially because this need to be strong.
Here is a shot of the plans showing the bend radius and the new wing attachment ordered from Steen Aero.