All,

I have started building the re-released vesrion of the DPR Models' Rare Bird. The original kit that I had i the early 80's I remember it flying very well (i.e. it was stable) inspite of my very dodgy building and covering.

The re-released kit benefits from really good laser cutting and wood selection; the kit is also very complete so it make a good choice for the absolute novice. Consequently this model is going together extremely quickly.

My plan is to build it as a 2 channel radio model to aid its trimming and then pull out the reciever and replace it with a Dens Models' E-Zee servo operated DT unit. I don''t expect it to compete with a Kiel Kraft Caprice, but it might prove to be a bit more versatile.

Anyone else had a go at this one yet?

All,

Here is the uncovered airframe built as kitted. I will shortly be modifying the tail-plane act as stabilators and the rudder will be hinged (probably Blenderm tape.

Weights so far are:
47g for the unballasted uncovered airframe;
78g for the uncovered airframe plus radio gear and CF push-rods and plastic outer.

It took all of the radio gear up front to get the recommended C of G position on the rear wing spar, so apart from the inclusion of the push-rods and the stabilator mechanism and the additional nose ballast AUP would be same as if it were left as intended.

One feature I think that the kit would benefit from is auto-rudder along the lines of that used in a KK Caprice.

Still working on the stabilator mechanism.

Since the model is very tail heavy in standard guise, I am trying to keep the tail end as light as possible. Key points are;
1. 4mm OD, 3mm ID carbon tube stabilator joiner rigidly glued to each stabilator.
2. "Outer bearings" made by wrapping the carbon tube with two wraps of sacrificial Mylar (sandwich bag) then wrapping with Esaki tissue and thin cyano. When total wraps are thick enough to be robust enough, the tissue tube is slid off the CF tube and cut to length to give the two rings. The Mylar invariably breaks away from the inside of the tube and can be pulled out; any residual radial 'slop' can be take up by running a small drop of thin Cyano around the inside of the tissue tube.

By the time I have fitted the fin and rudder into the "bearing box" things are getting quite fiddly - this is the sort of assembly that would integrate into one part - i.e. design in a 3D CAD package and get 3D SLS printed from bearing plastic material...

Hmm- good to know. I have one of the older kits in my stash- thinking about 2 channel RC as well. Even with RC gear, my Caprice wound up in the top of a very tall tree (I was letting my brother fly it- he didn't get that guided FF airplanes are not very maneuvrable.

Sam

Nearly done the tail feather group. I will post some more photos when I have finished fettling the tail mounting to get everything square and level.
Then, just need to sort out the servo and push-rod mountings...

Sam,

One of the reasons I chose the Rare Bird over the Caprice, apart from nostalgia, was that I think that its combination of flat bottomed wing section and tail layout would make it more responsive and possibly more versatile in light winds.

That said, I think I would have to be very lucky for it to stay up like I sure that a Caprice can; a Caprice is definitely on my build list.

Hmm- I may have to "borrow" your idea on the stabilator. Many years ago, I framed up a second Satellite wing and stab- might use a solid balsa fuse rather than build one up. Did the stabilator trick as well- just been sitting around. I really liked how the Satellite went- think I preferred it to the Caprice, but the Satellite was pure FF and of course, got hung in a tree and that was that.

If you've got some breeze to contend with- I wouldn't be surprised if the Rare Bird does OK- or you might want to think about sloping it.

Sam

Finally got around to doing some more work and sorting out the canopy and push-rods. All seems to work well now but have had to use an even smaller receiver.

I'm looking at your radio gear-it seems that we have similar concerns. Ever since I went to 2.4 GHz gear, I've been reluctant to go back to a single cell lipoly pack- hence I've flown my gliders with 2 cell packs and occasionally repurposed a brushed ESC as a voltage regulator. I haven't been able to find a smaller BEC than a Pixie 7 though. It's kind of annoying- would be a lot easier if the 2.4 GHz gear would work on a single lipoly cell.

You opted not to do pull-pull control. On some of my smaller airplanes, I've used just some aluminum (or should I say aluminium since it's an English airplane?) tube as a control horn and some UHMWPE for control lines threaded through a servo arm - use two arms for the control cables- use a third arm as a kingpost- allows length adjustments- well sort of.

I'm sure the airplane will fly well- I keep getting the urge to build a smaller sloper...

Sam

Have a look at the Lemon DSM2 Micro 6 Channel Receiver (LM0025) from Micron RC (in the UK). Will accept a voltage range of 3.45 to 10.2 V (I left the BEC unit on for ease of connection and perhaps to protect the servos - claims to be full range.

Thanks for the suggestion! I may have to try one sooner or later.

Sam

All,

Whilst I am waiting for the tissue to dry here are a few observations on the generally excellent Rare Bird kit:

1. The 3mm x 3mm spacers that glue between the wing ribs and to the front of the trailing edge would be better (I think) if a slightly taller section was used say 6mm x 3mm and then sanded back to be flush with the ribs. This would help promote neater, easier covering in this area.

2. The clear canopy is supplied flat and nicely cut but I found it too thick to bend easily, I have used some similar but much thinner material from some scrap packaging - much easier to fit and bend after scoring.

3. The kit's tissue paper is interesting. I have covered the wings, stabilators, fin and rudder in lightweight Esaki tissue and Ezedope, but have run out of white Esaki tissue, so I thought I would finish the fuselage using the kit tissue. This kit tissue seems to have fair to good wet strength is much easier to handle than Esaki, but has a very open "weave"? and will require a lot of Eze-dope to seal up its surface. However, I suspect that this tissue might work well if used over Mylar...

Is it really a tissue? What you're describing sounds like a light weight silkspan. Odds are it'll be thicker and heavier than Esaki. Is there a shiny side? Might be some form of bamboo paper as well- not sure of the difference between silkspan and bamboo paper though. I think bamboo paper has a shiny side but silkspan doesn't- at least that's what I've seen. I haven't tried Eze-dope yet, so I can't comment on the difficulty in filling. Haven't done tissue over mylar either...

Sam

Taking a little while to finish the final tissue trimming, seem to be making a lot of mess for a little model. I have found that the kit tissue will seal up well with 2 coats of 60-70% Ezedope.

Just one thing about Ezedope - when dry will still "bruise" easily with finger pressure; but allow to cure properly in bright sunlight (UV?) and I think it is more durable than cellulose dope.

Some more photos below; AUP is 116g but will end up around 120g to get the CofG at the position shown on the plan (guess at around 60% of root chord). When I have sorted the trim, I might be able to save on a few grams of nose ballast by drilling into the nose block and getting the weight further forward.

Will put the water slide transfers on and add a pilot later...


Radio and servos seem to be well up to the job but time will tell.