HK Waco SRE

[Erfolg]

I am assembling the HK Waco SRE.

I have arrived at the point where it says, to keep the wings on using cup hooks and elastic bands. I screwed the cup hooks in where a pre-drilled hole is provided, only to find that when i slid the wings on the Aluminium spar, that the hooks hit the wing root, as there is no aperture or hole for them.

I considered making a hole, then discounted the notion, as the wing root, on the cabin, is pretty weak, with a quite a few holes. An additional one immediately adjacent to the spar, will almost certainly weaken the area to a degree that would concern me.

Has any one else built one, what was their solution?

I have considered partially filling one of the holes in the wing root that equates to an identical one in the cabin. So that the rubber bands can go through the cabin. Though non seems that well located, to pull the LE and TE together equally..

Edited By Erfolg on 08/03/2017 14:25:16

[Dwain Dibley.]

Hi, I'm not familiar with your model but, ...I have a couple of biggish models where the wings are retained with bands.

The hooks are on the wings and the bands pass through the fuz, however, I have drilled the ally tube and spun a machine screw, slightly oversize, through the wing and into the tube to hold the wings. The screw will cut it's own thread. The wing tube then stays in one wing when de rigged.

Hope that helps, i can post pics if you need them.

D.D.

[Duncan Disorderly]

Hi Erfolg, there are vertical slots in the fuse for the cup hooks to pass through. The slots are next to the hole for the spar. Quite small and fiddly. Had me for a while too but figured it out in the end. You'll need to slice through the covering. At work ATM so can't help more as it's not in front of me. Cheers, D

[Duncan Disorderly]

p.s. from what I've read people are using cable ties to hold the wings together rather than elastic bands. Seems sensible to me!

[Erfolg]

Duncan, I was just about to reply, but there are no slots. Then I went to my modelling room, peered across the inside only to spot a vertical slot. Oh, dear.

I am at a loss to see how you could use cable ties on the upper wing. although it is not a solution that i would feel at ease with.

It is apparent from Dwains suggestion, how lightly constructed this model is compared with many others.

I am a little disappointed in the strength of the wing roots on the body. If I could have gained access without surgery to the upper body I would have re-enforced all 4 positions.

Looking at some of the pictures posted, it is apparent that the UC area on the body is very weak, susceptible to damage. I have re-enforced this area with Light Ply, in a pretty much standard way, for many kit or plan models. The irony is, I have replaced ply which has been removed by the laser cutting. Then added some.

I have found the instructions, absolutely pants. I have loads of screws left over. I replaced the aileron horns and clevis etc, with some better made items.

I have this feeling that this may a first in-house designed and out sourced build, as so much is not quite on the money, yet the overall finish is good. I am guessing that many of the HK ARTF, are designed and built by others, then badged by HK.

Anyway, back to finishing

[Duncan Disorderly]

Yes I'm semi-tempted, once it's all assembled and "final", to just epoxy the wings on. At 1300mm span I'm never going to take them off anyway and it may save a bit of faffing about. I've got it as my summer Sunday afternoon toodle-ship so I'm not overly worried about the construction. I may do a little reinforcement as I go if needed but I think it's alright for what I've bought it for. It's a Hobby King ergo instructions such as "affix the thingy with the bits supplied in the box" are the norm, as is the need for better horns & clevises. I've definitely got some extra bits too... Some lovely pics around of it with a pretend radial in the front but I worry about cooling with most of the cowl blocked off. I'm going to do something about the windscreen even if it's just painting the wood behind it black. Seems to be a sweet flyer from what I've read about it so I'm looking forward to finishing it off over the next couple of months, ready for the three weeks of summer. Cheers, D

[Erfolg]

Duncan

I am now surmising that you have not attached the cowl?

As my next question was and is, any tips on how to do it?

It is my intention just to stooge it about. Although my one time PZ Stinson Reliant, I looped, of course tempted to roll, so very barrelly, and tried inverted flight, here tip stalling alarmingly. It just shows you need discipline to fly a model in character, some of us just fail.

[Duncan Disorderly]

No not yet. I've read that it simplifies things greatly to remove the blind nuts from the fuse and put them in the cowl, then screw the bolts through from inside the plane. Otherwise you'll need a 6ft long magnetic bendy allen key and the patience of a saint (I have neither). On mine it looks like one pair of blind nuts is partially behind bits of glued-in ply so I may leave them in and simply put a set in the cowl too and get slightly longer bolts... the important bit is bolting it on from inside the plane rather than through the cowl.

Search youtube for the 1300mm WACO 30E ARF - RCGroups Review (cut & paste it) and at 1:49 you'll see the high rates roll - it's going to need rudder and elevator on the way round I think!

Off for the weekend now and as I live in the 18th Century at home I won't have internet access again until Monday...

[ted hughes]

You might find help here: **LINK**

[Duncan Disorderly]

Thanks Ted - I was wracking my brain trying to remember where I'd read this stuff - and not even my own link to the RCGroups review nudged my poor head...

[Erfolg]

I thought an update on how I have got on, may be of interest.

I arranged the cup hooks exactly as suggested by Duncan. I then pulled the elastic bands across exactly as i would do on a glider. On this model it is much easier as the elastic bands do not generate the same amount of tension as is commonly used on the old style open gliders. There is a difficulty in that the fuselage is very much wider. This means that the standard glider guider elastic band tool can not be used for much of the process.

The picture shows at the top, the piece of bent wire I used to pull the bands through. Just beneath it is the Glider pull through device, used to hook up the hand on the far side cup hook after pulling through. Dead simple, really quick. No need for cable ties, or turning the cup hooks through 90 degrees. The problem with the other solutions is that they probably do not provide any give.

I read the link that Ted provided, which provided some ideas. I did try the small soc set type extensions, although even at approx. 3/8" diameter, far to bulky. I tries a soc, screwdriver with an Allen (hex) driver inserted, still to large a dia, this time the soc end, principally.

I then thought I would try a solution as per the link. In my case i epoxied a hex rod into a brass rod, used by fastening an old tap wrench i made as a teenager, back in the 60s, part way along. I do not do brazing, not having any silver solder, flux or a gas torch that will reach the temperatures required. Also heating up the assembly will all but destroy any beneficial properties from processing. Which is almost certainly an issue on such small cap headed screw, hex driver. Glueing works fine. That is the bottom item in the picture picture.

Much to my frustation, the screws would not go into the tapped holes, without trying to cross. By chance i found a soltion, which made the job a 5 minute operation. I used a wooden barbecue scewer as a driver, by making a hex on the end, this did not fully go into the hex hole in the cap head, but did transmit a drive to get the scres pretty much all the way in. I did not photograph this item.

A few pictures of the know assembled model.

This last picture shows the method i have used to hopefuuly prevent a loss of the hatch, as reported on the link, apparently it can happen.

[Duncan Disorderly]

Looks lovely Erfolg and I may try out some of your solutions. One thing that slightly bothered me was the lack of an exit hole for the air - I wondered if that's why the battery hatches are falling off... Please let us know how it flies!

[Erfolg]

Duncan, you are correct, there is no std hole in the fuz to allow air out. It probably is a problem because there are plenty of holes in the bulkhead and the motor mount, to let air in.

The link shows one model that has been enhanced by additional UC and windshield detailing. Really does make a difference to the appearance. In my case I am happy if it flies and looks OK from a few yards off.

[Erfolg]

It is some time since I built the model, if building can be claimed, assembly is a better description.

The first flight went very well, which was undertaken by the guy who does the first flights for me. The second by me was also successful and uneventful. However the third did not happen as the model leapt into the air, then crashed on its nose, nothing was apparent to cause this, that is other than me. The forth was a similar diaster. Every one present was adamant that i stalled the model. I was far less certain, as I had deliberately kept the model on the ground for a good few feet, it left the ground, then immediately piled in.

On this occasion the model suffered some obvious superficial damage. Home it went, for careful examination to establish how much damage. Shortcomings in the construction became apparent in addition to damage commensurate with a crash,

The first which I am now fixing is the upper wing dowel arrangement. The wing dowel itself is an aluminum tube, this survived unscathed. However it locates into a GRP tube of such exceptional thinness that it is akin to tissue paper, these have just shattered.

The tail assembly is made from light balsa strip, which have lasered tenons along the edges to take cross pieces. As you might expect the tailplane has failed at each of these locations. Now fixed, although I fear a lot more work in the future, that is if i am lucky.

The possible cause of the crashes might now be apparent. The mounting plates for the inter plain struts had become loose in a number fixings. The general lightness of the model structures allows the wings to move pretty randomly. I am now also poring glue into these fixings.

It has taken me a while to get around to the repairs, just because I have preferred to fly and had other things to deal with.