King Altair

[Bob Cotsford]

Finally I've made a start.

First, the model - in the early '60s Ed Kazmirski (Taurus) and Vic Husak (Altair) were big names in aerobatic competitions. At the time they were flying 60-70" models as was the trend, but they thought that larger, slower models would produce more elegant aerobatics. To this end Kazmirski came up with his 100" maxi-Taurus, the Simla. Husak was a little more conservative just going for an 80" span with the biggest of his Altair models, the King Altair. Maybe they were ahead of the times as the winning competition models remained sub-70" for another couple of decades.

The King Altair was flown in the early '60s and eventually featured in the American MAN magazine in '67, more recently being kitted by Classic RC Hobbies in the States.

 

The Classic RC kit arrives as a plain but sturdy cardboard box 48*9*8", not big by ARTF standards, but there is absolutely no wasted space in there. The two rolled sheets of the plan are each 2' wide and around 10' long! Then comes half a dozen laser cut sheets of ribs for both wing and tail, laser cut fuselage sides + formers and doublers, bundles of 36 and 48" sheet and strip, a jet-style bubble canopy , pre-formed wire for the fixed u/c and a bag containing smaller laser-cut parts and DuBro fittings. Half a dozen A4 sheets cover the construction and include a couple of pages of in-build photos. as you might expect with a model of this type, the instructions don't go into a lot of detail as anyone building this model is expected to have both construction and flying experience. Things such as the wing dihedral and CofG are presented as suggestions on the expectation that builders will know how they like their models to fly.

 

 

[Bob Cotsford]

Sorry BEB, it's both sleek and trike!

 

So I got stuck in with the tailplane which is just a leading edge and ribs with 3/32 sheet top and bottom. I've not had much experience with laser cutting, but I am impressed with the accuracy of this lot - I've used a C/F rod as an alignment aid, that and the tabs cut on the ribs should keep everything straight. The rod will be removed once the sheet is dry.

The instructions suggesting completely sheeting the tail then cutting off the elevators and trimming back the sheet for the elevator LE and tailplane TE capping strips. Seemed a bit of a waste of wood to me so I just left a gap in the sheet where wood would have been removed.

First after cutting off a suitable chunk from the wallpaper roll plan I set everything up over the tailplane section with a strip to line up and support the trailing edges of the ribs and the C/F rod to keep the ribs aligned

 

No, I'm not building it with UHU gp glue, it just happens to be lying there.

 

Next I started adding sheet leaving a 5/8" gap at the hinge line

 

Once that side was sheeted, I turned the tail over, removed the tabs and started to sheet the second side

You can see the ends of some 3/8 sheet peeking out along the hinge line, these are the hinge blocks cut from scrap. They will be trimmed back level with the sheet later.

 

 

Now I'm waiting for the PVA to dry before cutting off the elevator section and capping along the hinge line.

[Bob Cotsford]

Just for a laugh, here's a full size FunJet for comparison.

 

[Big Bandit]

Hi Bob,

 

You sure know how to pick em, looks the absolute monkeys from the pick's and description, watching with mounting interest.

 

Cheers,

 

Chris.

[Alan Cantwell]

classic aerobatic, MMMMMM nice, do you have a link to look at? are there any more in the range?

[Bob Cotsford]

have a look here Alan, they've got the K.A., Simla, Tauros (Taurus), Oryon (Orion) and Qwik-fly (guess what!). The kits are well cut but some of the sheet and strip supplied could be better cuts and weights, nothing too bad or unusable and nowhere near bad as a Marvic Models Joker kit I had.

There seem to be quite a few suppliers for kits/short kits for classic 'pattern' models in the USA, like the BlueJay Bridi designs. Then there's Sunshine Modellbau in Germany.

[Alan Cantwell]

some nice stuff there, and on an american forum, i hear mention of an artf Curare, happy times!! i own a 39 yr old Kwick Fli, enlarged from the american plan, and built by the guy who taught me to fly! still in good flying order, and still with the original engine

[Bob Cotsford]

Posted by Bob Cotsford on 02/01/2012 21:57:11:

The kits are well cut but some of the sheet and strip supplied could be better cuts and weights, nothing too bad or unusable and nowhere near bad as a Marvic Models Joker kit I had.

I'm going to amend this bit having had a closer look at the sheet supplied for skinning the wing - 4 of the sheets are good, stiff quarter grain hard balsa - excellent for cutting ribs, not much use for skinning a wing. One sheet has a knot smack in the middle with what looks like a worm tunnel along it, and two of the remaing three sheets have some degree of splitting - probably from heavy handed carriers.

As these sheets are 48*4*3/32 to cover the full 40" panel length I might just clip this one's wings to use 36" balsa, it will still give a 76" span with the tip blocks. That or I order some 48" lengths from SLEC or Balsa Cabin.

[Bob Cotsford]

A bit more done, the tailplane is finished and the fin/rudder are about to be skinned.

With a three foot tailplane I can see hangar rash being more of a problem than usual, so I split the tip blocks and added a layer of 1/16" ply.

 

 

To save bevelling the elevator LEs, I used 3/8" triangular capping

 

 

The material supplied for the fin and rudder bore no relationship to that shown on the plan, though there was an addendum sheet noting that the thickness had been increased from 1/4 to 3/8". I used the lightest of the supplied wood and added a couple of pieces from the scrap box to replace one piece of table leg.

 

Now, to slot the tip of the fin for a ply insert, or just soak it in cyno?

[Bob Cotsford]

Not a lot of progress to report to date, so a quicky.

I'm going for the full 80" span 'Classic; version having obtained some more 4' sheet from SLEC, between this and the wood supplied I can get a decent selection for the wing skins.

I first ordered a 1" ali tube and sleeve set from Falcon Aviation, but they are in mid-move and the order went astray. When I eventually got through Richard was most apologetic about the failure to despatch, but by then I'd switched my order to Mick Reeves. MR supply tubes in 36" lengths, whereas Falcon will supply the exact length you want which works out a little cheaper when you only 24". Still, if you don't get the tube the price becomes irrelevant. I understand Falcon will be back to their normal fast service 'shortly'.

The alternative supplier is Fighteraces, who supply metre lengths of gold anodised certified aircraft grade tube, but at a price.

 

I also heard from Jeff Petroski at Classic RC Hobbies, who was very apologetic about the wood supplied being on the heavy side, explaining that this is exceptional and reflects is the sad state of balsa supply to small concerns in the USA. OK, so I'll be replacing 3 or 4 sheets of wood, maybe more, but it's still good value compared to something like a Great Planes or World Models kit.

 

Anyway, back to the build. I started the wings by drawing in the joiner on the plan aiming for it to span the first 5 rib bays, with W6 acting as an end stop preventing the tube disappearing down the wing. Next to plot the vertical position of the sleeve in each rib, I chose to go for 2 degrees of dihedral as it makes things easy. 2 degrees is a gnats whisker off 1/32" inch rise for every inch of span. If I've got that wrong, please leave me in blissful ignorance as it's too late to change things now.

First step was to add some ply doublers, principally these tie the tube sleeves to the spars, so the doublers were long enough to achieve this and no more, except W1 which got a full length doubler, and W4 and 5 where the doubler extends back to tie in the UC blocks. So really only W2 and 3 got the minimalist deal. The doublers are 1/32" birch ply for W1, 2 and 3, with 1/16" on W4 and 5 for the UC tie-in.

Next I marked the chordwise centre lines on ribs 1-5, and started with an offset of 1/8" above centre for W1 and set this as my datum. By measuring how far each rib is from W1 in inches and multiplying by 1/32 I got the offset from the datum for each station. EG, if W3 was 5" from W1, then the offset is 5/32" below the datum. A pair of springbow compass fitted with a blade scored the outline of the hole, these were cut through and then cleaned with the trusty Dremel.

 

Next step is to start pinning bits over the plan!

 

OK, so it wasn't such a quicky after all

Edited By Bob Cotsford on 16/01/2012 21:14:08

Edited By Bob Cotsford on 16/01/2012 21:16:36

[Bob Cotsford]

nearlt there!

This was the state of play a few weeks ago:

and after a surprising amount of time covering and fitting out it's nearly there

I've just fitted a nice shiny alloy spinner and 14*8 prop, that just leaves a zaust to tack on the side.

How do reviewers seem to fit out a model so quickly? These last stages seem to be the most traumatic to me with more fiddling, reworking and cursing than any other stage of the build!

[Big Bandit]

Looks brilliant Bob, I agree that fitting out is the most time consuming to me, probably because I keep changing my mind about detail .

Cheers,

Chris.

[Bob Cotsford]

Thanks Chris.

Today it passed the club noise test so it took to the air - 3 clicks of left trim and a couple of up and that was it. To descibe the flying characterictics as 'stately' is a wild understatement, it just progresses along the flightpath in an unhurried manner and goes wherever it's pointed. I'm flying it on a 90 2 st, back in the 60s it would have been powered by a cross-flow 60 - that must have been an excercise in energy management.

I just need to move the CG back a bit to improve the inverted performance, bbut overall I'm delighted with it.

Result!

[Big Bandit]

Nice one Bob that is so slick . Theres certainly some thing about early patern ships that have a presence in the air and on the ground. Top Job.

Cheers,

Chris.

Edited By Big Bandit on 01/04/2012 19:35:29