Junior 60 fuselage

[Lowandslow]

I need to build a new fuselage for my electric Junior 60 following an unfortunate incident in the hanger and while I’m at I thought why not extend the out of proportion  snub nose by around 40-50mm and try to lose some of that annoying 8 ounces of lead which was previously required to achieve the correct  CofG. I’m also pondering whether shortening the tail end by 30-40mm would also help swing the moments in the right direction. Has anyone any experience of a similar modification? (Albert Hatfull has no need to know about this discussion) 

[Outrunner]

My electric powered Junior 60 has a little lead in the nose, I can't remember how much but it's only a small amount. The 3s 2200 battery sits almost vertical behind the motor and it flies beautifully.

I think what you are proposing will be a strange looking Junior 60 with a long nose and short tail, but I hope you get it flying again soon whatever you decide.

[Lowandslow]

Thanks Outrunner I like the vertical battery concept.

[Outrunner]

35 minutes ago, Lowandslow said:

Thanks Outrunner I like the vertical battery concept.

If you're interested I can take some photos of my setup tomorrow.

[PatMc]

I don't think Albert specified a cg position for the Jnr 60, I believe it was left up to the builder to trim the model to suit himself by trial & error. 😉 

Post Keil Kraft kits - by Flair & Ben Buckle show cg positions on their plans but IMO they were overcautious & didn't take into account the generous tailplane area & longish separation between wing & tail. I have the Flair version built around 1986 then refurbed & electrocuted 2012/13. 

Originally I went with a cg a little further back than the plan then after the refurb I started with it at the same point but removed the ballast incrementally over a number of flights until there was none. The model is well behaved with the cg 3.5 cm behind what's shown on the plan. Result is a much better glide & greater speed range.  

 

PS which version is yours - the Ben Buckle / early version or Flair later version with wider fuselage ? 

PPS here's a link to the refurb thread

Edited September 17, 2023 by PatMc

[Lowandslow]

Thanks Pat that’s really useful. It’s a Ben Buckle version. Come to think of it my glide was a bit of a hurried affair so moving the cg back should improve that.  Outrunner when you get the chance I’d appreciate some set up photos.

[Outrunner]

Hi Lowandslow, I take it back about the lead, I found it too nose heavy with a 2200mAh 3s battery pack so I removed the lead.

 

Sorry about the rotated photo, the first one is with the cowling on, the next showing the top of the battery and the motor, the third shows where the battery pokes through bottom of the bulkhead. I had to cut a hole to allow the pack to sit down a bit lower. The pack is canted over at about 30 degrees to allow the cowling top to seat correctly. The battery is easy to change and the perfect weight to balance the model. When I first converted the model years ago with a brushed motor and nicads the battery pack was under the wing and was a pain to change hence the update to brushless and lipo.

 

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[Lowandslow]

Many thanks for the ideas gents…..Now must order some balsa.

[David Davis]

My first successful r/c model aeroplane was a Flair Juniot 60 powered by an Irvine 20 car racing engine. Unfortunately I made the tailplane out of the heaviest wood in the kit. This resulted in my having to put one and a half pounds of lead under the engine to get the c g in the correct position. (Yes thats 1.5lbs or 0.68kgs!) It still flew well and taught me to fly r/c.

 

I built a lighter tailplane for it later on and was able to remove all of the lead.

[Phil Green]

Pull-pull linkages can save a few grammes  🙂