flyinrog

My Feedback: (1)

Been a bad couple of years, mines still setting on the work bench..except the canopy section IIRC one of the dogs made a snack out of it...Rog

Mr Cox

You really should get it up in the air, glow or electric, they fly really well. Great inverted and outside loops are a breeze, it is only the knife edge that has alot of coupling due to the high diheadral. I have added a few degrees of engine downtrust, to reduce the climb at full throttle, but appart from that it is unchanged. The wing could possibly have lower angle of attach too but it is not so easy to change.

I been wanting to get a second one for spares just in case I make a dumb misstake, but they are discontinued now. [:'(]

John C

I just got one from Tower Hobbies and thought my idea of putting a Norvel 074 in it was a new idea! Not so as shown from the thread attached. I was planning on installing the engine upright, but now I think I will go the inverted route. It looks like I need to cut the present motor box about 1" ahead of the front fuselage former and make a firewall mount to accept the DuBro mount the engine is installed on. I'll maintain the current down and side thrust.


I'm using Hitec HS65s all around except for throttle, so servo power should not be a problem. Interesting enough, this engine is on its original glow plug even tho I'm using 30% nitro R/C car fuel with castor added to get the requisite 20% oil.


Wing servos and linkage installed, waiting for epoxy to dry from joining the wing halves.


John C

Mr Cox

I think an upright engine would destroy the lines of the plane and I didn't want to cut through the nice looking cowl.
The position of the tank is very important with inverted engines, make sure that you can get that low enough, it needs to be at the very bottom of the fuselage. Battery goes on top of the tank right behind the firewall. I have changed that since the very first image in this thread was taken.

I would have liked to play a little with the wing incidence on mine, I think that it is set a little too high, but that is hard to do with the current wing attachment. Instead I've increased the engine downthrust (at the engine mounting lugs), it is not the same of course but it reduces the climb at full throttle a bit.

Mr Cox

Here two more pictures I had on my computer of the engine installation. In order to not cut in the cowl I made a DIY muffler from thin aluminium tubing and some JB-weld. It holds up just fine, clears the cowl and puts the outlet at the bottom, leaving the plane cleaner. The built in spring starter is very nice to have too. I prime and start the engine while holding the plane upside down, and even though it fires I'm often struggling to get enough spin on the prop but the spring solves that.

I few years have gone since I started this thread the plane is still in good condition. It is only the landing gear that is a little weak and tends to bend after a little hard landing, this comes mainly from the wires being from a softer material than regular music wire. Might bend some new ones from a proper wire, it should be straightforward to do with only two bends to make.

John C

Thanks for the additional pics! I was wondering how to handle the muffler interference with the motor mount box. Does anyone know of a muffler extension for the provided muffler - 1/4" should be enough - and longer screws to mount? I may still do an upright installation...got to figure this through some more. Anyway, the wings are complete with landing gear installed. The wire for the landing gear seems OK, but then I'll be flying off our fabric runway.

John C

John C

Just an update, model assembly is complete and I am working on the conversion now. I decided to mount the engine horizontally; the head will stick out about 1/4" and exhaust will work with the supplied muffler. I need to pick up some acid brushes and soak the front end with epoxy before I mount the firewall. I have a Thunder Tiger 2.5 oz. tank that fits after some mods to the original firewall to get it to the right height. Progress is being made!

Mr Cox

The TT 2.5oz tanks are nice, lightweight and compact. I have added a third line to mine, it's at the rear top of the tank and accessible under canopy. This can be used for filling and emptying (with plane upside down) without having to do anything at the cowled engine.

MJD

My Feedback: (1)

I just found one of these on the shelf yesterday.

John C

Mr. Cox, how did you attach a spigot for the third line you use for fill? I'm planning on a 'T' in the carb line for filling at the moment.

AARG!! My thrust line is set too low as I found out after epoxying in the firewall I need to raise the engine about 3/8" to get the cowl to align correctly. Pic 1 shows the misalignment. The blue vertical line shows where the cowl should go; the blue horizontal line where the thrust line needs to be. The second where the thrust line should be vs. present location, and the third a general view of right thrust and tank location.

John C

Mr Cox

I used the back end of a drill, the drill should be smaller than the desired hole. The method is the same as when making fueltanks from film-canisters. Heat the backend of the drill up and use it melt a hole in the tank. This way you will not crack the tank and the melted material will build up around the hole and strengthen it. You can then fit a silicone fuel line into the hole with a squeeze fit and it will not leak. If you want to secure the line from being pulled out accidentally, then fit a metal or plastic tube in the end of the fuel line that stays in the tank.

Yes the engine is sitting too low at the moment, you could possibly drill new holes in the engine mount or firewall and shift the whole thing higher up. I don't think it will affect the flying much, but aesthetically it will look better. Mine is also tilted down a little as I felt it needed more down thrust than I had initially, and I didn't want to shift the whole engine mount up.

I also think they messed up a bit with the red paint on the cowl. I don't think that it is possible to have the red paint line uninterupted or straight, but the lower part of the cowl can possibly be flat with the rest of the fuselage.

John C

Mr. Cox, thanks for the insight on the tank. I tried moving the engine up with a new firewall, but the tank won't work as I can't get it up high enough and the outlet spigots interfere with the motor mount. Looks like I'm off to plan 'C' which is an inverted mounting that allows the use of the current tank and motor mount; however, I'm out of 5 ply 1/8" plywood and the weather here wasn't conducive to riding the motorcycle to the LHS some 10 miles away today. I'll take the stock exhaust out the side of the cowl, but it does look like the front will need to be worked on for throttle arm clearance, etc. Two steps foreword and one back, but we'll get there!

John C

Mr Cox

The tank looks more than high enough to me, remember that it is the spray bar in the carb that one should look at. The spray bar can be higher than the center of the tank, but preferably still below the topmost part of the tank. With an inverted engine I had to place the tank at the very bottom of the fuselage, and it is still a little rich on the low end with a completely full tank.

Could you move the tank down and back a little, to make more space for the firewall and engine mount?

John C

Here's a shot of my final setup. The supply line is located at the bottom of the motor mount, pretty well on the spray bar C/L and also the C/L of the tank.

Reinforcing of the firewall extension still to be done. By eyeball, the muffler will just fit within the cowl, with the exhaust spigot extending through the cowl.

John C

Mr Cox

I'll can check my tank height later today, from memory I have it as low as the fuselage will allow...

I think the very front part of the muffler will hit the cowl a little, while the rest fits nicely inside. The outlet can also be rotated downwards, and extended with a silicon hose, to keep the side of the plane clean.

Mr Cox

Looking at your last picture, it looks like the tank could be lowered another 1" or so. The spray bar would the be closer to level with the top of the tank which I think works better, the fuel will then not siphon to the carb on its own.

I have taken a few more pictures of the inside of mine. The tank sits as low as possible in the fueslage. The third line and electrical switch are positioned under the canopy which is very easy to take on and off, for fueling etc. I start the engine while holding the plane more or less upside down, a regular handheld glowdriver is enough for the glow plug and it will usually stay in place well if it is the sure-lock style rather than twist and lock.

John C

I got out this morning and got several flights in. I started with an APC 6X3, but ended up with a 6X4 as it seemed to pull better. Fuel is 30% nitro car fuel with 10% more castor added. Weight is 20 oz with a 720 NiMh AAA 4 cell battery pack and balance is spot on.

Flying is really stable; I increased the aileron throw, but elevator and rudder seemed about right. It spins well in both directions, both upright and inverted, does a nice knife edge, and is an all around nice flying model. I'm impressed with how well the Norvel runs inverted. I can't tell any difference from upright, which was a nice surprise. I didn't tach idle and top end. Takeoffs and landings are easy.

Here's what the cowl looks like: . If I had to do it over, I think I would install the engine at an angle clockwise, maybe 15 degrees looking from the front, to possibly hide more of the muffler. Now to put the decals (stickers) on and find a pilot to fit! It's a keeper!

I still have a Herr Lil Extra originally designed for the Norvel .074. I had put a OS Max FSR .10 in it and still felt it was underpowered so it now has about 300 watts of electric in it and flies with great authority! I've heard a .15 is about right in these.

John C

Mr Cox

Congratulations, I'm glad it worked out for you too, it is a really sweet combination I think.

I'm using an APC 6.3x4 prop on mine, a 7x3 might also work fine, but I like to use a pitch of at least 4 on throttled engines. That way they will fly well at reduced throttle settings too.

I have put baffles around the engine on mine, but you have much larger cut-outs than I have so you might not need it.

MJD

My Feedback: (1)

I decided to join the club.. I snagged the Chipmunk earlier, and an .074 NIB came up in the Canuck classifieds, it showed in the mail Friday.

If I didn't snag the .074, an OS .10 was in the wings. I am sure it would work out fine as well, but at a penalty of maybe 3 ounces in the end.

Likely I'll use the 500 mAh Smart Lipo, 2.8g Lemon Rx receiver, HS-65's, Hayes 2 oz tank. I'm loving high capacity Lipo Rx packs.. instead of fanatically turning the Rx on as late and off as quick as possible, now I can be quite lackadaisical about it. Which helps on compact models with fiddly Rx switch setups.

John C

Welcome to the club! I've ended up using a 7X4 APC prop and 30% nitro car fuel with added castor. I forgot the car fuel and tried the 15% I run in my larger planes and could tell a significant difference in the air. I'm also using HS65s but an AR500 Rx and a 720 MAH NiMH. I've got a 300 MAH I've thought about using, but the weather looks like flying is over for this year. Good luck with yours!

John C

PS - I don't use a switch, just plug into the Rx since the canopy assembly comes off easily.

Mr Cox

The OS .10 could work fine in terms of weight I think (depending on the model, the later ones are heavier than the FSR). With the Norvel engine I have to put the battery right up against the firewall for correct balancing.

I have flown mine on a 7x4 prop once but the engine didn't like it, perhaps a Cox or Rev-up 7x3.5 would work better. The APC 6.3x4 is pretty much spot on though I think, and gives better vertical than I got from the 7x4.