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Posted by LittleJon | Feb 22, 2007 @ 02:20 AM | 3,081 Views
The repair of my MiniBOP is now complete! It's a great feeling to see a plane that at one point I had considered unrepairable is now ready for flight. I still have to check the CG, but apart from that it's ready to fly. Hopefully I'll have time tomorrow (Thurs) lunchtime.

I wanted to reduce the elevon throw without affecting roll speed. I thought I could do this by adding an end point adjustment to channel 1. Unfortunately, on an Optic 6 at least, end points seem to only affect the servo throw pre-mix, so only one servo was affected. Instead I've had to just move linkages to a lower hole on the elevon control horns. In case you haven't read my earlier posts, the reason for my needing to reduce the throw is that on my second flight a hard up caused a stall resulting in a nasty crash.

Another minor change is I've swapped the existing (and damaged) 4.75 x 4.75 prop for a 5.25 x 4.75. A static test with a slightly discharged battery suggests both the TP 2100 3S1P Pro-Lite and the 35A Phoenix should cope.

The attached photos show the plane after the rebuild.
Posted by LittleJon | Feb 15, 2007 @ 12:27 PM | 3,134 Views
After discovering that my stocks of EPP were almost at zero, I had to borrow (on a permanent basis) some from a friend at work. He brought some in yesterday, but then discovered a block of some other unidentified foam somewhere at work. This foam seems similar to EPP, but without the cell structure. I weighed and measured it and found that it is 1.7x denser than EPP.

I decided to use this foam, as it seems tougher. While denser, I only need a small volume so the weight difference will be insignificant.

I hand cut a new nose section last night. I'm pretty pleased with how it went. Now I have to cut the old nose off and graft on this new one.

The photos show the new section and the state of the old nose. This new piece will replace just the last 5 inches or so. You can just see lines where I started to cut away the front of the original, before realizing that it was getting very late last night.
Posted by LittleJon | Feb 11, 2007 @ 04:10 AM | 3,119 Views
I've just spent a merry few hours repairing the wings on the MiniBOP. Actually it was more wing (singular) as most of the damage was to the right wing. The worst damage was to the end six inches or so, although when the motor came off in the crash, its wiring ripped out of the foam and made a nasty mess to the extreme right of the left wing too.

I'd actually been most concerned about that area, as the wiring still had clumps of foam and covering stuck to it that I feared would never go back in to place. In the end I was pleasantly surprised by how easily it fitted. I used foam safe CA for most of the repair work, but where I felt extra strength or gap filling was required I employed polyurethane glue (Elmer's Ultimate).

Next I'll move on to the fuselage. This sustained the most damage in the crash, but my plan is to completely remove the front six inches, leaving the carbon central spar intact (amazingly this survived) and fashion a new section from spare EPP. It's going to be tricky to match the clean finish of the original, but hopefully any inadequacies will be purely cosmetic.

Where there was despair there is now hope!
Posted by LittleJon | Feb 07, 2007 @ 01:55 AM | 3,123 Views
Today could have gone better! After flying the Edge 540 in an attempt to combat with a couple of work mates (there was only one hit which didn't involve me), I switched over to the miniBOP. I'd been flying for a short time when I throttled up in order to do a high-speed dive from which I intended to pull up sharply. I'd done this kind of maneuver a thousand times on my old miniBOP and I expected it to do it's usual spectacular thing. It certainly was spectacular, but not in the way I had intended!

The plane refused to pull up and slammed hard in to the ground. I could see the vertical stabilizer fly off, but everything else was out of sight in the brush. When we got to the crash site it was a bit of a mess. The nose (fuselage) section was badly smashed and there was damage to the wing. It took us a couple of minutes to find the pieces. The battery was about 15 feet away.

My initial thoughts were that it's not repairable. However, now I'm not so sure. I've not taken a proper look at it since putting it in the trunk of my car, but I think the wings are repairable. If I can find enough EPP I could probably build a new fuse. The real question is whether it's worth the effort vs. building a new one from scratch. I'll have to give it some further consideration.

Of course the big question is what caused the crash? Why didn't it pull up? Initially we thought the servos had come loose in flight under the high forces involved in the dive, but it seems more likely that that...Continue Reading
Posted by LittleJon | Feb 06, 2007 @ 01:39 AM | 3,725 Views
The maiden went remarkably well. All that was needed was two clicks of up trim and the plane was trimmed out. Roll rates are even higher than my last miniBOP. It's hard to estimate, but it's several rolls per second.

The only issue was that when I tried WOT the motor cut out after a few seconds. My assumption is that the low voltage cut off tripped in. I plan to try a 4.75 x 4.75 prop next and see if that solves the problem.

Speed-wise the plane is fast. Damn fast in fact! I'd like to get a radar or doppler reading sometime.

On landing the plane suffered a small amount of cosmetic damage to the underside of one wing. While the landing was soft, the ground at my flying field is hard baked earth and loose stones. A couple of years ago it was lush grass and the main challenge was to avoid ending up in the marshy regions. This year we've had virtually no rain, hence the condition of the field.

I've added a few little foam stand-offs on the underside that hopefully will minimize this type of damage in the future, although landing on a rough spot is still likely to result in scratches.

I'll try to get some in flight video next, if I can find someone who's quick enough to keep up with the plane!
Posted by LittleJon | Feb 05, 2007 @ 03:20 AM | 3,301 Views
I've just finished building my new Mini Bird of Prey (miniBOP) that replaces the old one that was destroyed by interference on my channel (this was verified using a scanner, so it wasn't just the old excuse).

I've was sitting on the kit for some time while doing other things (like getting married). I think I'd reached the point where I had run out of enthusiasm for building planes (my custom, collapsible aerial photography plane has been on hold waiting for me to check the CG after making an adjustment to the tail). This was partly due to the lack of space in my small apartment. What little space we have gets used by my wife for her fashion design. Hopefully we'll be moving soon to somewhere with a lot more room, however it's going to be sad to say goodbye to Laguna Beach (one of the few decent places in Orange Count, in my opinion).

To get back on topic, this weekend has been something of a building spree. As well as finishing the miniBOP I also built a Phase 3 Edge 540 EP 3D Profile that I bought from the local Hobby People for the bargain price of $19! This is intended for combat with an Ultimate Bipe that a friend at work bought at the same time.

The miniBOP build has taken a while as I covered it using grumman5277's "Stressed Skin Technique" (see: Stressed Skin Technique Thread). One difference is I used "fusible interfacing" (my wife gave it to me) that has an iron-on adhesive coating on one side. This eliminated the need to spray 3M 77...Continue Reading