Strengthening Bud Nosen Citabria

Hi i am wondering if anyone else has put a petrol engine into a bud nosen 1/4 scale citabria and if so where, how and what was used to strengthen it? recomended engine is .60 - .80 Glow and i have a 32cc petrol engine already bolted on the front.


Malcolm Knight

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Malcolm Knight
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Mods to make on the Nosen Citabria to accomodate a 32 to 42 cc gas engine: 1. Replace the lite ply firewall that comes with the kit and use 3/8" birch ply. 2. Replace the top balsa stringers from F1 to F2 with either spruce or basswood stringers. The 1/4" ply fuse sides are fine as per plans, but be sure to use epoxy to bond them to the sides of F1. 3. Drill 4, 3/8" holes about an inch from each of the corners in both F1 and F2. Then epoxy 3/8" birch dowel rods that will connect F1 to F2. Sand the dowels flush with the front surface of F1. The combination of these first three mods provide, in total, a very rigid structure that will easily handle the gas motor. 4. Because you did #3, you can now OMIT the BOTTOM stringers between F1 and F2 and instead, make a removeable, bolt on, hatch that fits between F1 and F2. This will make it MUCH easier to work with the fuel lines, throttle linkage, and fuel tank. 5. Install the plywood wing hold down blocks as per instructions. BUT, then drill 1/4" 45 degree diagonal holes that go from the center of the wing hold down block and out through the fuselage side. It will come out halfway between the top edge of the windows and the top edge of the fuse side. Then epoxy in 1/4" dowel stock in those 6 holes (three on each side). Then trim the dowel stock flush with both the top surface of the wing hold down blocks AND the fuse sides. This adds the additional strength needed for the heavier engine as well as the higher G airbatics you'll be doing with the bigger engine. Be sure to NOT place any of those dowel rods where the wing bolts go through the hold down plates. Just put the dowels through sort of toward the front, near middle, and then toward the back of the hold down block. Don't overdo it; 3 per side is all you need. 6. Save the supplied landing gear for some other glo engine project, and replace it with a heavier duty aluminum or dural landing gear. You want the gear to also add about an inch to the height at the front to better allow the longer prop clearance you'll be using. The supplied gear will bend almost every landing you make so don't even THINK of using it on this aircraft.

Since you've already bolted on your 32cc motor, you may not feel like tearing apart some of the areas as mentioned above to redo them. You choose and take your chances. I've built four Nosen Citabrias and two of the Nosen Champs so I learned from experience. Hope this helps.


"Malcolm Knight" wrote in message news:

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I fly my Champ with a 3W twin engine 48 cc (5HP) Mounted the engine on an extra piece of plywood and screwed it to the firewall. Wingfixing by aluminium pipes. Massive wood in the centersection. Total wingmounting by thicker bolts( 6mm) Formed (as the original Champion) a new aluminium heavy landing gear. Total weight now: 9 kg. And its not overpowered! But it has the power to tow gliders and gives me a lot of pleasure to fly it. note: the weelaxles are replaced by steel ( no normal bolts) because of the weight.


"MJC" schreef in bericht news:botf83$

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I have interjected some comments to this post. My bird had a 3 inch gas burner.

OR use 2 1/4 inch ply laminated together.

Use a woodpecker to make sure the epoxy penetrates both pieces of wood.

I replaced the corner stringers (top and bottom on the plan) from front to rear with spruce and added carbon fiber bracing at the sharp bend 'break' points.

Yeah, but a lot of work and it is a BIG fuselage. Gas burners don't need the fuel tank all the way forward.

I made mine out of 1/4 inch T6 and the problems (I learned about them on the .40 sized plane) went away.

One other major modification you need to make. The struts ARE structural and they do flex. I made mine out of hardwood and then made the jury strut to prevent them from failing when inverted. A little more weight, a lot of work, but peace of mind.

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Been flying mine for 4 months now with a US 41 engine. Very nice combination. Check the strings on RCU about the CG. It will need to be about 1 1/2" ahead of the plan location...Very important. I mounted 3 servos in the rear of the fuse to help with balance. I have mixed throttle with rudder and ailerons with rudder to get the plane to fly straight and fly level thru turns..

Beautiful plane to watch fly and lots of fun to fly. I also used an aluminum wing tube for extra strength. I also went to 3/8" dowels(two of them to hold the leading edge of the wing to the front support and two 1/4" bolts thru the top of the wing and into a 1/4" plywood brace epoxied across the rear of the fuse wing opening to secure the wing to the fuse. I did not use the 4 bolt system shown in the plans. Much easier to get the plane ready to fly and to disassemble. Using flaps and ailerons. Flaps are great on this plane. Covered mine with White and orange Coverite. Looks great.

Good luck.


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