John A

Well, the pictures aren't the greatest, but here's a few to spur some conversation. I made a lot of changes to my latest Patriot. I moved the canopy way forward, and inverted the engine, to give it a look like the F86D. I wanted great Knife Edge, I was never happy with the engine sticking out the side. Just hoping this OPS isn't as picky as my older ones. I put drop tanks on the end of the wing. I left off the stock wingtips, and just put a piece of 1/4" balsa to reinforce the outer rib. It has a square of ply inset in it the spring presses against to kick the tank off (see pic). Nice and clean after drop, plus the brass tubing in the tips should make a cool whistle.

OPS 40 SPP plyon (RIRE), was NIB. I probably haven't played with the timing yet. I can't remember if I'd changed the intake vane or not before I packed it away. I'm still bench running it. Im trying to get it under 18k to keep it quiet, but I'm up to an APC 10*7 and still up to around 18500. I think I'll live with that. Once I'm done, changing props (which means pipe length change) will be difficult. I stuck a 9*8 on it and was up over 20k (ear plugs mandatory), so I'm going to be stuck with the wide blades if I don't want to get run off Perry 3/8 bore carb.

I made a large one piece cowl that goes back to the rear of the wing. Four #4 screws hold it on, then I can get to the quick release on the bottom of the wing for the Tuned Pipe. After removing it, the wing will slide out from under the pipe, without having to loosen any of the clamps. The rudder was enlarged to make up for the increased frontal side area. I added a piiece onto the stock vert. stab leading edge that goes from 3" wide at the base down to nothing at the top. More in line with the pics as I post em.

John A

Heres the tank and the inside of the cowl. For the tank, I wrapped 1/32 balsa around and STP cleaner bottle then let it dry. I made round end caps for it, then made a half round piece of wood (1/4" to start with) that I layed into the inside edge. This let me carve out the opening for the wingtip, then I layed a flat piece of 1/16 inside of it to cap off the hole. I made a U shaped braket to glue inside of it. On the inside of that I mounted a pin which sticks out through a hole drilled in the sheet. The pin is nothing more than a PC board stand off. Its a long one, and I used it because it's already tapped for a #6. It fits perfectly inside the brass tubing that's installed in the wingtip. I then put a spring around the pin, attached to bottom of the U. Lastly, the pin has a notch cut out that matches the latch in the tip. The cable is a simple pull mechanism. I only supported the cable near the servo, so I can just push the bombs back on and they click into place. More on the latch in the next post.

The hatch is modified for the canopy. The nose is still stock length, as is the firewall location. The black magic marker line you see about even with the end of the white monokote is where the firewall is. You can see where I hollowed out the wood for the fuel tank, starting just about 1 " in front of the 2 screws that hold in Buzz Lightyear. It tapers down to about nothing where the tabs at the rear are. I still have to finish the trim tape on the canopy.

John A

Here's the latch. Just two pieces of brass that fit tight inside each other. The inside one is filled with solder. Strenthens the tip (which is tappered to a 45) and allows me drill a hole for the wire that goes to the bellcrank. The solder should keep the hole from rounding out. I don't expect a lot of wear, here. Bellcrank and mount are lite ply. Bellcrank pivots on yet another PC boad standoff, with the same brass tubing epoxied into the ply for a bushing. The standoff is just a little longer than the tubing, and then a screw and washer are put in on the bottom just like you see on top. Loctite is used because Im not putting a hatch on. Don't ask me how many times I've dropped the tanks for everyone that's been over I put some advantage in crank, then added more later when I realized just how short a throw I needed for the release. That's the reason for the extra hole (turned it around and tried again). No need for keepers or z bends unless the bellcrank comes loose.

John A

The cowl. I mounted the engine, then stuck the pipe on, and guessed it needed to be about 1.75" tall to cover everything. It's made out of mostly light 1/4" balsa that's rounded off and then thinned down. I've still got to add aluminum in the back, and the white outline for the bird up front. The engine is cocked over a few degrees for the pipe to clear the retract, which is offset to the right of plane to help out. Thats why glow plug hole is off center. The cowl tapers down to fit between the wheel wells, then widens again to meet the body in the back. There's a scoop on the opposite side, viewable in the next post, that gives room for the cylinder and head.

John A

This is the almost complete nose. The piece of pushrod tubing sticking out is opposite the needle valve. Scoop in side was added when the head wouldn't clear the side, and I didn't want to rework the thing. Turned out for the better, I think it's neat. The outlet for the pipe is visible through the wing opening, as is the location of the wheel wells. Sort of like those area rule fuses on the century series of fighters (coke bottle waist of the f-105, etc.) The bottom is kind of dull. I sanded it out with 1000 grit, before I add the trim lines and clearcoat it. I hope to have it done within the next 2 weeks.

John A

Here's the tank. I've got a 12 ounce Dubro. It's not sitting flat in this photo because the lines are holding it up (Yanked it off the test stand for the photo). Just about 1/8" above fuse side when done. You could lower the retract mount plate, or just round out the top like I did. I like the lines better anyway. This is the last photo until I get it done and get my camera back or get a new capture card. Well, unless of coarse someone wants something else.

Razor-RCU

My Feedback: (50)

Holy schamoley! Great work!!

I could not be more impressed by your workmanship-

I can't even get the correct right/down thrust and you do this?

Must be nice trying to stay < 20K for RPM's

I have 2 planes too loud for the field, this is the next one to get tested- (with Jett-50)

Keep us posted,
james

John A

Nice plane, Razor

I got into the OPS engines many years ago. This is the last one I bought, I think in 94. They are picky picky to set up with a carb, at least the pylon engines. I've tried them with and without the Perry Pump on the carbs, and I've found for this installation I've got the best runs without the pump and running crankcase pressure, not muffler. I put a check valve in the case line so I can fuel it up without flooding. These engines are made to really rev, so I'm fighting cooling problems with the large prop. I've lowered the compression to where I can run an OS A5 plug, and haven't burned it after 5 full tanks on the bench, so I think I've got it. RPM's are now a steady 18200 running rich enough to see a good exhaust trail. I may stick it on my old airmadillo to check it out good. I've done a lot of work in the cowl to redirect the air and raise the pressure. I should have made the intake much smaller but I've blocked off a lot of the flow to help cool it. Most of the air bypasses the engine. Around the back of the engine I did work to keep the air pressure up. Maybe I'll do the whole plenum chamber thing over the winter.

phuffstatler

My Feedback: (20)

Looks a bit like the old Curare fuselage....

Neat, neat. Good luck with it...

phil in austin