Another What is it? thread

[Bob Cotsford]

Can I call on the collective experience on here to help identify these two models from an e-bay purchase?

#1 - the primary purchase:
66" span, 13" root chord, 54" long, foam wing, diamond section tailplane (feels like foam?)

#2 - an almost complete 40-60 size model, 59" span, 41" long that came along for the ride:

[kc]

The first one looks a bit like a Kaos 60 or Sunfli 4 or another Joe Bridi design.

[Bob Cotsford]

after a 'little' time browsing the net, I think it's a Marabu:

I think the Kaos has equi-taper and the SunFli straight wings. Now I need .60 with bolt spacing of 47*25mm (old Irvine 61?), most .60s use 0*25 or 50*20mm. Otherwise I need to commit butchery on the nose to fit a more normal engine.

[Paul Marsh]

Would be good for next years' Bardoe Vintage model fly-in. At Sleap.

[kc]

Yes it looks like a Marabu its the elevator completly behind the rudder that means its not a Kaos. Marabu mark 3 is a Model Airplane News plan No FSP 07721but its 66 inch span 53 inch long.

Sunfly 4 did have tapered wing.

 

A Merco 61 I have has 47 x 24 ( approx ) spacing. I might swap it..........

[Bob Cotsford]

if it lasts that long! So far I've swapped the (immaculate) FD15M and FD16M servos for a mix of HB325BB and 3003s, which means I just need to make a decision about a motor. The mounting is hardwood beams blocked in all around, so trying to move the captive nuts (4BA?) would involve major surgery. A modern OS or clone will be too wide both in the crancase width and the mounting lug width. An Enya 60-III will fit between the bearers but the bolts are 52mm*20mm. I'm thinking that screwing threaded 4mm inserts into the bearers might be the way to go.

The PO thought it had probably had an Irvine 61 in, but as I've only the Enya, Super Tigre or OS .60 2strokes or a Magnum .90 4 stroke it looks like some sort of surgery will be needed. As the engine length isn't limited to any real extent I might just plump for the 4 str.

 

The second model, the red one, looks somehow familiar but I can't think where from. Some jet-style model from the 80s maybe? So ugly it's almost cute. It may make a decent winter hack, if not we can gather round for a warm-up as it burns.

 

Question - where to get off-white (Ivory) film to match the Marabu's wing? I don't know whether it started off ivory, got nicotine stained or just yellowed with old age but it's not Solarfilm type white now.

[Eck]

In a similar vein, I was given this aerobatic model by a clubmate a wee while ago. Coincidentally, it's of approximately the same dimensions as Bob's find, has a rolled ply fuselage, foam wing and sheet tail - and the bearer dimensions matched perfectly to an old Irvine 61. I've just fitted it out with 3003s all round and ar500 Rx, and now only need to find Imperial bolts for the muffler. Can anyone identify her, please? My generous clubmate has had her in the attic so long, he can't remember what she is!

[Bob Cotsford]

I cant link this in, I guess our works policy is stopping the 'add images' popup, but try looking for Trenton RC Classics pages in Google. Lots of photos on there, it's how I identified mine as a Marabu. edit - click on the initial 'I' - something linked it in!

 

Kc, sorry I must have overlapped with your reply, My biggest problem with old motors is likely to be a) getting them under the club's 80dB limit, and b) to be honest I'd get as much or more power from an old SC53 I've got in the cupboard as from a Merco 61. It looks like it will be either the ST, Enya or a 4st.

Edited By Bob Cotsford on 06/12/2011 13:12:41

[kc]

I would suggest sawing off the front, underside only, removing engine bearers, and replacing with a plastic or ali mount as the easiest way. Drastic, & never done it but its just an idea.

 

The film might be the old Polyfilm etc. Or it might be old Solarfilm which is thinner than 'span and lets the wood show through. Application of different colour trim seems the easisest way to disguise a repair. ( I have done this and I 'cannot see the join' when it's flying! )

Maybe cleaning the old film with ' Cif / Jif' might get the old bit lighter? In any case use Prymol etch primer ( Solarfilm product ) to get a secure film overlap. Dries in a few minutes.

The more interesting Trenton sites is  Trenton plans & articles which has the articles and plans to download for many classic pattern models

Edited By kc on 06/12/2011 13:50:45

[Bob Cotsford]

if only, kc, if only. This is the only model I can remember owning where the engine bulkhead is about 2" further back than needed, as though it had been designed for a rear inlet motor and the designer then allowed an extra inch 'because he could'. The bearers are surrounded on three sides by blocks forming the nose, hollowed out to be a close fit around the crankcase so it would be more a case of cutting off the whole nose and making a new cowl if I wanted the bearers out.

 

I tried cleaning an area of the wing with cellulose thinners around the hole in the covering, but it stayed an ivory rather than pure white. WTH, it's on the bottom, no-one will notice if I keep it inverted after take-off.

[kc]

Cut the whole nose off, fit a mount on a suitable spacer bolted right through.  Then seperate the balsa top & side from the bearers and epoxy the balsa back on to form just a top & side cowl.

Edited By kc on 06/12/2011 15:23:40

[Bob Cotsford]

I can see where your going with that, but this was just a cheap punt on ebay not a restoration project! I really want to keep work on it to a minimum, so I think I'll try the inserts first, if that doesn't pan out it will be keyhole surgery of some form rather than wholesale butchery requiring lots of recovering.

[kc]

Using the rear 2 of the existing captive nuts would be safer and just put a bolt up through the front pair. ( plug existing hole then drill right down in correct place to get a pilot hole, then up from underneath to clear a nutdriver to hold bolt head.)

Im right out of ideas now!

[Bob Cotsford]

for better or worse I've gone for the inserts. My reasoning is, if they're good enough to hold a radial mount to a bulkhead, they must be more than strong enough to hold an engine down on a beam mount. The Enya is in.

Now I just need to fuel-proof the engine bay and get some sort of exhaust system on, time to see what's at the bottom of the cupboard. I should have a JE Genesis pusher pipe assembly that I can modify by reversing the outlet.

 

[kc]

I think this thread has proved the whole purpose of the forum.........someone posts a question then we ( the usual suspects ) give some answers, then we play Devils Advocate and suggest all sorts of crazy things. This goads the original enquirer to a bit of lateral thinking and hey presto he solves the problem himself! QED.

 

Seriously Bob, a photo or some info on the inserts might help others.....

[Bob Cotsford]

Lets give it a go then, I've got the engine out to fuel proof (Solarlac Clearcoat * 2) and fit the fuel tank lines:

The inserts are from Modelfixings, have an external helical flange that cuts into the wood to stop them pulling out, and a hex socket to drive them in with:

 

 

Not really much to see, I've slotted the engine lugs to match the existing rear bolt holes, and added inserts for the front:

 

Edited By Bob Cotsford on 07/12/2011 22:12:26

[Bob Cotsford]

the lugs on the old Enya 60-III BB are wider than modern engines so I could get away with slotting them: