18" Eastbourne Monoplane - RC Groups
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Feb 11, 2013, 04:57 AM
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18" Eastbourne Monoplane

Following the Sperry Monoplane build over on the scale forum I felt it only fair to post the next build here.

With laser cut parts acquired and a clear building board available (and being held up on the Sperry waiting for bits and pieces) I set to on the little Eastbourne. With just one fuselage side and the wing panels built there isn't much to show yet. However, this is what I have in mind for it.
As in the title, it's 18" wingspan. Construction will be totally conventional balsa and a little ply with tissue covering. I'm aiming for a finished weight of below 40 grams (the further below the better) and control will be provided by a Vapor brick operating rudder, elevator and throttle. Power will be an AEO 7 mm geared motor and 160 mAh Nano Tech battery.
I'm hoping this little model will have similar flying qualities (slow and stable) to my larger, 48", 20 ounce model. I'll post photos once there is something worth seeing. I think we're all pretty familiar with what a wing panel pinned to a board looks like.

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Feb 11, 2013, 07:19 AM
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PeteSchug's Avatar
Sorry about the link to a Sperry Messenger and babbling about printing a steam engine.

I've got peanut plans for the Sperry Monoplane around here someplace but so far they have not turned up.

Looking forward to yet another plane I would love to have with no room left to store it.

Feb 11, 2013, 10:04 AM
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Absolutely no need to say sorry for anything mate. I enjoyed reading the Messenger thread.

Currently I'm debating what finish to use. A local model shop that stocks dope is about as common as hen's teeth. An on-line search revealed several sources, but also showed something called EZE Dope. With low odour and water clean-up I wondered if it might be worth a try. Has anyone used it? Is it any different to WBPU? Should I just stick with what I'm used to?

Feb 12, 2013, 06:26 PM
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Oh well, after a day playing around with different finishes on printed tissue, I now know what Eze Dope is like BL**DY RUBBISH. Much too thick, heavy and aggressive for my needs.
This evening saw a little progress on the Eastbourne, so I suppose I'd better post what few poor photos there are. Looking at pictures is always good. Probably not that interesting in this case though.

Tail laninations are 1/32 balsa strips, soaked well, glued up with white woodworking glue and pulled into place around the waxed edges of the Depron forms. Small blocks of balsa hold them in place and are added as you pull the laminations around.

The one laser cut part I'll have to change is the little rectangular former in the centre of the 1/16 balsa parts. The edges are a lot thinner than they looked while I was drawing it. Probably make it ply instead. A bit of weight up front won't go amiss. Then maybe it won't break so easily. I glued mine back together with a couple of strips of the laminating wood reinforcing the edges.

Feb 13, 2013, 01:53 PM
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scrubs's Avatar
I'll be curious to see what you think of the AEO motor/gearbox setup. From a picture it looks identical to the 7mm sold by Hobbyking. There were a number of complaints when it first came out about thrust not matching specs and a soft propshaft.

If it works I already have your 13" Eastborne printed out at 18" and a couple of the Hobbyking 7mm's which I've never tried. Also have the GWJ 7mm gearbox which puts out about 28 gms of thrust.

Feb 13, 2013, 05:10 PM
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I have just a gearbox, labelled AEO, that was actually bought from HK, so maybe they are one and the same thing.

Feb 14, 2013, 10:29 AM
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scrubs's Avatar
I looked at the gearbox only on HK and it's a bit different than what I have. Mine has a long section of unsupported shaft. On the current ones it looks better supported.

Feb 16, 2013, 09:29 AM
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With the arrival of my new razor plane, and a printer problem putting the skids under progress on the Sperry monoplane, I have been able to do a little more to the Eastbourne monoplane.
The wing panels are now trimmed and sanded, but still have locating dowels and rigging tubes to add. Mustn't forget to add them before covering because the rigging is all that holds the dihedral on this model. When it comes time to assemble it I'll glue the wings to the fuselage while it's all jigged up and then runnthe rigging cables from top pylon to bottom pylon, passing right through the wing tubes. Back onto the jig and, once it's all to my liking, put a spot of CA into each rigging tube. It works well on bigger models so I'm figuring that if it fails on this tiddler it's because there isn't much left for the rigging to rig to. So far they weigh in at 2.5 grams for the pair.

The laminated tail outlines now have a fin/rudder and tailplane/elevator attached to them. They are mostly sanded, but still have the control surfaces to be separated and some rudder/elevator leading edge rounding to be done. As they currently stand their combined weight is 0.7 grams.

The basic fuselage box is built, trimmed and sanded but can't have much more done to it until the motor is installed. Unfortunately that means sealing it in with the top deckings but there doesn't appear any real way around that.
Once I get a little further with it, and before covering, I'll probably cut away a large proportion of that lower nose plate you see in the photos. It's really only there to ensure the nose pulls in evenly, so much of it is sacrificial. As it stands, the fuselage weighs 3.1 grams, which is a little more than I'd hoped for but does include a 1/16 ply u/c plate.
In case you're wondering, yes, the u/c plate SHOULD go right across the sides. Another slight mod to make to the plan and cut file.

The other job I got done was to make up the bulk of the carbon rod parts - u/c legs, upper pylon and lower pylon. Nothing complicated there. Just pin them down over the drawing (suitably covered with cling wrap), with a piece of stripped electrical wire under them. Add a spot of CA and allow to set. Once set use the rest of the electrical wire to bind the joint before adding another spot of CA. A light trim up, removing excess glue, trim off the ends of the wire and the job is done.
Fitting the top pylon to F2A proved a little more problematic than I expected, but only because I actually fitted it to F2B. Fortunately I spotted it before the glue dried completely. Just a case of slicing it off and fitting it to the correct former. As you see them, including F2A, they weigh 0.3 grams.

With the current weight total at 6.6 grams I may yet make my 40 gram maximum with a little to spare. Just depends on how heavy the dummy engine ends up.

Mar 02, 2013, 06:32 AM
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Now that I have the little Sperry Monoplane completed and test flown I can get back to working on the Eastbourne. Hopefully it will benefit from lessons learned while covering the Sperry and turn out much nicer for it. This tissue covering lark isn't anything like as easy as I remember it being.

Anyway, although it was only fiddly stuff I got done last night, the model now has a 7 mm geared motor fitted and the top deckings glued on and sanded. Considering the decking had to be fitted around a rigging pylon, I'm reasonably pleased with the way it came out. I need to get some covering on the fuselage before installing the brick and pushrods. However, before I can actually do that I need to draw up and print the tissue covering that's going on it.

While I'm working on the tissue files I can make a small modification to the wings. Even water shrinking the tissue I'd covered them with was enough to distort the root ribs so I'll just add a narrow strip of 1/32 balsa to the inboard rib to prevent that next time. As soon as I cut away the covering everything straightened up again nicely, so the wings don't need replacing too.

I'm not absolutely sure how I want to do the tissue covering. I have some cream tissue but it has minimal wet strength. Covers okay dry and water shrinks fine, but goes a bit transparent when doped. It doesn't seem to happen so much when treated with spray fixative instead of dope but I still have to make up my mind whether or not to print the base colour, or live with the natural tissue colour.
I'll post some more photos once things get more interesting to look at.

Mar 02, 2013, 08:44 AM
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Have you considered spraying a stain finish onto the tissue? There are several such stain-and-sealer-and-finish coatings available in the USA, and I presume they would be available in the UK.

In my batch of kits to build "someday," there is Pat Tritle's Eastbourne mono. Span about 45" IIRC. Someday...

Jim R....
... whose "somedays" diminish...

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