Frog Jackdaw resurrection.

[Colin Leighfield]

I have gathered such an armada of Models over the years, unfinished projects, others I keep saying that I will get around to but never will, that I could hardly move in the shed to build anything comfortably and the roof space in the garage was so jam bang full it was hardly accessible.

Therefore I finally bit the bullet and did a deal to get rid of most of it, so enough to fill a shop went yesterday. I now have proper working space and accessible storage. Back in the shed tonight I have recommenced work on the Fury top wing. Also I pulled out my Frog Jackdaw that I last flew in 1979 and assembled it with elastic bands. I bought it off a work colleague when I hadn’t done any modelling for some time, although I had dabbled previously with single channel. On a different thread some time ago I note I mentioned this plane and that I had acquired it in 1976. That was wrong because I left the place of work where I bought it from my friend in 1972, so it was probably about 1970. In 1976 I decided to get back into flying and bought my first set of propo gear and an OS30, thinking the Jackdaw would be perfect for me if set up with this radio and engine, which it proved to be. On the photos you will see the C&M Models sticker still on the fin. That stood for Clive and Mike, who had set up in Kettlebrook Rd. Kingstanding. A couple of years in Clive moved on to run a seafront model boat business in Spain and the shop became Mike’s Models, which it still is today. Mike and Jean Leavesley retired many years ago of course. The radio was Swan, actually manufactured by Wico Pacey, the “Wipac” business so long associated with electrical equipment for motorcycles, now long gone. I had good experience with the Swan gear and used it reliably for a number of years until I changed over to the excellent Sanwa “Black” radio, first on 27 and later 35 MHz. Because my Jackdaw didn’t have ailerons, (you could build with or without), I flew rudder, elevator and throttle. It performed very well. One day in 1979 at Greenacres when flying serenely overhead, the Jackdaw suddenly nosed down and dived vertically into the ground. A colleague standing next to me had switched on his radio on the same frequency, very apologetic but the damage was done. Actually it wasn’t that serious but the O.S. 30’s carburetter was broken and needed replacing. I didn’t bother to repair the plane but stashed it away and it hasn’t been put together again until today, 40 years ago. You can see the superficial damage and the dirt and staining on the nylon covering, which is actually generally in surprisingly good condition in the undamaged areas. I have decided to get it back in the air, at this stage not bothering with total restoration, so it will look a bit tatty with a definite patina! I am fitting an Enya SS30, which although the same size as the original sedate OS30, probably has twice the power. I plan to fly it at the SAM35 event at Buckminster in late June. There is a possibility that it will be condemned as too unhygienic to be allowed on the site, but one can hope!

[Dwain Dibley.]

I love this sort of thing Colin, I cant wait to see the results. I think the resurrection of old models is a worthy pastime, wish you all the best with it.

I was given a Double Diamond that has similar age, when a club mate passed away a few years back. I refurbished and flew it, and thoroughly enjoyed every minute of it.

I hope you don't mind me putting a pic in your thread.

D.D.

[Colin Leighfield]

Not at all Dwain, I’m glad it created the opportunity. These planes really fly, they have a fascination all of their own. Not to mention the nostalgia for old duffers like me! (Head still in the clouds of Sutton Park, a long time ago)!

[Dwain Dibley.]

Simpler times Colin....................

D.D.

[Piers Bowlan]

Formulite Peter Christy is quite a fan of the Jackdaw. I hope he doesn't mind me adding this link to the video of his ASP30 4st powered one. A nice video and I thought it might give you inspiration for the resurrection Colin.

Edited By Piers Bowlan on 29/05/2019 08:59:50

[Colin Leighfield]

Piers, thank you. That took me right back. The performance with the OS30 FS is probably similar to mine when it had the OS30. The Enya SS30 has more poke, but that isn’t a reason to chuck it about, I will use the throttle sparingly. The Jackdaw is perfectly aerobatic though. It won’t take long to get it sorted, I have already fixed the wing.

[Peter Christy]

Best of luck with the Jackdaw, Colin! As Piers says, I'm quite a fan of them! I really don't understand why people insist on extensively modifying Super 60s to end up with, effectively, a Jackdaw!

I'm a little disappointed with the ASP30. Although it has plenty of power once airborne, it takes a loooong run to get off! It doesn't seem to turn the prop any quicker than my OS20 FS did! Its also very critical on the needle valve. Maybe it just needs a few more hours on it...

I do find the ground clearance for the prop marginal, and if the grass is at all long, this will induce a swing to the right on take-off as the prop catches in it. You also need a lot of up elevator during the initial take-off run, otherwise all that down-thrust will make it nose over. Big wheels help!

It is a beautiful model to fly, though. It cruises around effortlessly on half throttle, and is extremely relaxing to fly.

Enjoy!

--

Pete

[Colin Leighfield]

Hi Peter. Although it is 40 years since I last flew it, watching your video was a case of deja vue! With the OS30 two stroke it also had a long take-off run on grass and I frequently used to hand launch it, which was very easy! Yet I had seen them with 3.5cc diesels take off with no problem. In the air it was fine and looped from level flight. I thought hard about fitting a four stroke but suspected a 30 might be a bit marginal and a 40FS probably on the big side, so the choice was a 30/35 two stroke. The Enya SS30 gets very good write-ups and should drop straight in where the OS used to be. Also it is significantly more powerful than the OS was all those years ago, so I think it will be fine.

I’ll post up more info as I go along. Once it is sorted I might re-cover it and make it look better, but in its current dilapidated condition it looks quite appealing, a bit like next door’s dog just before they had it put down.

[Colin Leighfield]

The Enya SS30 arrived today, what a nicely engineered motor. I dropped it into the engine mount to see how it looked and was surprised to find out how much narrower the crankcase is than the cut out in the ply plate that the OS30 used to fit into perfectly! I will have to make a new one.

[Dwain Dibley.]

Bling Bling...................!!

D.D.

[Colin Leighfield]

You know the feeling you get when something feels instantly right? I’m looking forward to this.

[Peter Christy]

You are almost tempting me to ditch the ASP30FS....!

--

Pete

[Colin Leighfield]

It might be worth thinking about Peter! I know we tend to put four strokes into these vintage planes because we think they are appropriate, but in truth in the days that they were ruling the sky, those didn’t exist! They were all diesel or glow plug two stroke powered and bearing in mind that the recommendations for the Jackdaw were “2.5/3.5cc diesel or 29/35 glow plug”, the best advice probably remains to follow that guidance. It seems hard to understand why the diesel choice was so small in capacity by comparison, perhaps it is because the lower rev “slogging power” of most diesels with larger propellers at low rpm gives more thrust at low air speeds, I don’t know.

With the two stroke choice these days, noise might be our main concern but the large volume silencer on the Enya looks as if it will be ok and I will err on the large side for the propeller, it looks as if the minimum will be the recommended 9.5x6 Bolly that Steve Webb seems to have in stock.

One thing I noted when searching for a suitable 30/35 two stroke, particularly looking at Just Engines and Steve Webb, it was clear that most of the recognised OS and ASP engines are listed as “out of stock”, is it looking ominous? I found the Enya easily on eBay and think it was a good buy for £70. I found another SS30 that was claimed to be new “old shop stock” for £30, but from the photos, although clearly new, it was obviously an older model with a smaller silencer, so I thought noise might be an issue.

Over to you. I know that many would “go electric” but I think it would be an insult to this old lady and completely unnecessary while there is no restriction on the continuing use of these very good small i/c engines for the foreseeable future.

[Piers Bowlan]

I have just been comparing the Jackdaw plan on Outerzone to the Super 60. Apart from a slightly thinner wing (less cambered) they are very similar. The significant difference is the Jackdaw has a good 5 degrees of down thrust absent on both the Super 60 plans listed. Neither model has any decalage as far as I can see from the online plans so why so much down thrust? I should come clean here, I have no personal experience of either model so I don't know what I am talking about!

Pete said that he had to use a lot of up elevator on the take off run, presumably to stop the model pitching nose down and the prop pecking the grass. Perhaps a little less down thrust might be beneficial and allow the model to accelerate more readily? Before you change the engine Pete, perhaps slightly larger wheels as fitted to many Super 60s, might aid acceleration too? What I would be interested to know is, on a go-around once full power is applied does the model tend to fly level or even pitch down requiring some up elevator to be applied? If it does then using a couple of shims to reduce the down thrust might be an interesting experiment?

I realise that the model was designed that way and there must have been thousands built but then it used to be a rudder elevator model and probably had more dihedral and therefore a higher drag line/ larger pitch couple with power. Hence more down thrust required to compensate? Whatever. The Jackdaw flies nicely in any event which is the main thing, just make sure your runway is long enough!

[Peter Christy]

Interesting comments!

Colin: Yes, the plans do show a 3.5cc diesel as power, and I think you are correct in concluding that these diesels had more "slogging power" than a glow of similar size. Certainly, a larger diameter / finer pitch prop improves acceleration, at the cost of top speed. As the Jackdaw is not a fast flyer anyway, the top speed is of little consideration. However the ground clearance of the prop is marginal when you get to 10" diameter.

The ASP30FS recommended props are 10x5 or 9x6. Strangely, my little OS20FS also recommended a 10x5, and I found it happiest on quite a broad propeller. It didn't like thin, slippery ones! But that was only hauling an Attilla around, much smaller than the Jackdaw!

Piers: Yes, I remember looking at the alarming amount of down-thrust when i was building it! However, having seen them flying perfectly happily in days of yore, I assumed the designers knew what they were doing! Mind you, back then they were always hand-launched (our strip was too rough for take-offs!). They were however rudder only (no elevator), and didn't seem to have any trouble getting away.

I have fitted a slightly taller undercarriage than that shown on the plans. I found a "Great Planes" dural undercarriage that was almost perfect. Funny how difficult it is to buy a dural undercarriage these days! Model shops used to have racks of them on the wall in days gone by...

I've also tried larger wheels, which do help, but make it look a bit caricature-ish!

From level flight, opening the throttle doesn't produce a noticeable nose down pitch, but it does cause an increase in speed, eventually leading to a climb. I think a reduction in down-thrust might be beneficial, but it would have only a minimal effect on the prop clearance.

I'm not going to pull the engine out without good reason, but if I do have to anytime soon, I'll put a couple of washers under the front lugs and see what happens!

Cheers,

--

Pete

 

Edited By Peter Christy on 31/05/2019 11:45:39

[Colin Leighfield]

I think you should leave the downthrust alone. This plane was designed by people who knew what they were doing. There are clear similarities with Chris Olsen’s Uproar, in fact if you drew a straight line from leading edge to nose and fitted a fully symmetrical wing, it is almost the same. The downthrust on the Uproar is the same. There is nothing alarming about it at all, almost certainly it gives you a much more neutral trim response as you increase power and suits the more aerobatic intentions of the design than the more sedate intention of the Super 60. With a good 35 up front and ailerons the Jackdaw was a very respectable aerobat and even on thee channels, mine was quite handy. Again based on my previous experience with the OS30, which was known to be a gentle engine and probably very similar to an equivalent four stroke in power, I would suggest that it just needs a bit more poke up front.i’m altering nothing on mine and have no doubt that the significantly greater power of the Enya SS30 will be all it needs to deliver everything that I expect. It won’t take me long to confirm that is right.

[Mike Etheridge 1]

I have three SS30's; one was 'as new' and I used it in an RM Trainer, another I fitted to a repaired unidentified Fun Fly plane and the other engine is spare. I think you are right Colin, your SS 30 has a larger silencer and I would be interested to how much your complete engine weighs ? . My SS 30 engines appear light in weight and small in size , the bearer spacing being the same as an ED Racer.

I think your comparisons with the Uproar plane are relevant as Stuart Uwins the Jackdaw designer was a friend of Uproar designer Chris Olsen.

[Colin Leighfield]

Hi Mike. I am sure I read somewhere that Olsen had a hand in the design of this plane. There is definitely a connection.

I looked at the technical stuff with the engine and it lists 210 gms, 7.5 ozs, however with the silencer fitted and 4x3.5mm bolts in the mounting holes (so I don’t lose them), the kitchen scales said 333! Not sure that’s accurate though, it feels light enough.

Edited By Colin Leighfield on 31/05/2019 18:18:09

[Peter Christy]

The Jackdaw was originally credited to Eric Walpole, who I believe was Frog's Chief Designer at the time. I'm sure I read somewhere that it was heavily influenced by the Uproar.

However, the Frog management apparently felt the original design was too ugly, and wanted it "beautified" a bit. Stewart Uwins was brought aboard modify it for production, IIRC.

There's quite a bit of background detail here: House of FROG including some pictures of early prototypes. Well worth a read!

--

Pete

[PatMc]

I must agree that the Jackdaw was far better all round than the Super 60. IIRC the S60 didn't even have elevators or provision for them shown on the plan, they were always a builders mod.

Back in the day I powered my Jackdaw with a 1960's McCoy 35 Redhead [Stunt version with throttle grafted on] later replaced with a Fox 25 rc. Whilst it had the McCoy power I reduced the downthrust in stages by around half & when I fitted the Fox I reduced it to near zero.

IMO the Jackdaw was reasonably well powered with either engine. The Fox was noticeably more powerful than the McCoy when both were fitted with silencers but neither had particularly reliable throttles - lots of deadstick practice.

I built the model with ailerons as shown but fixed them & flew RET for the first few months before buying & fitting the extra servo. Even with the dihedral as per plan the ailerons were effective, though if I was building a Jackdaw now I'd reduce it by about half & also have the thrust line parallel to the datum.
I actually still have a Frog 349 diesel as shown on the plan but I'd choose electric power.

BTW a few months ago I measured the Jackdaw rigging angles from the OZ plan - the thrust line is about 5.5 degrees, the tailplane zero & wing incidence is about 2.5 degrees (measured through the LE to TE) all wrt the datum.

[Peter Christy]

Interesting, PatMc! I take it you didn't have any issues with unwanted zooming when you reduced the downthrust?

Most of those I recall seeing in my early days in the hobby were powered by Merco 35s - as indeed was my Super 60, when I had one (6-channel reeds, RET)

A chap I spoke to at the Pontefract retro meet a couple of years ago was complaining that his had a tendency to stay in a turn, once initiated. I pointed out to him that it was originally intended as a competition machine, mostly rudder only in those days, and that this was a highly desirable trait for the job!

Even with the standard dihedral, mine will only slowly right itself - certainly much more slowly than a Super 60 - which in my book makes it more suitable for modern radio gear than a Super 60. However, I have had to add a bit of aileron differential, as it suffers a bit from adverse yaw.

I've spent years flying helicopters, so my left thumb is well able to cope with this, but as I hand the box around a bit, others have commented on it!

I still maintain that its the best model of that generation!

--

Pete

[GONZO]

Frog 349RC Engine test for power comparisons. Interestingly a 10X5 prop is recommended for ground revs of 9,000 - 9,500. The Enya 35IV RC used to be readily available on the bay for about £30. The plain bearing model will do over 10,000rpm on a 10X6 and would be preferable, IMO, to the Frog which can be prone to vibration if not worked on (practical experience, 10 Enya's and 4 Frog's).

[Colin Leighfield]

Peter, I think you have summed it up well enough. It isn’t directly comparable with a Super 60, it is more focused on all round capability including decent aerobatics. Here are a couple of pages from the excellent book “Frog Model Aircraft” by Richard Lines and Leif Hellstrom, showing Stewart Uwins with a Jackdaw in 1961, in rudder only form, winning competitions and describing how well it cope with strong winds. I definitely wouldn’t mess about with the downthrust because I think they got it right. The plan shows a “full-house” radio set-up from the very beginning, which fits with the understanding that while contemporary with the excellent Super 60, it had a different purpose. Also the photos we have probably all seen courtesy of Outerzone that show a prototype without the cabin profile, indeed more like an Uproar. Finally and a bit different, I also show from the Lines/Hellstrom book a photo of the contemporary “Frog Nimrod”, only 30” span. Some birthday money enabled me to buy one of these kits in I think 1960. Because I was otherwise skint and only had access to a well worn Mills .75, I fitted that instead of the suggested Frog .049 glow. Unfortunately the extra weight of that meant I had to add lead in the tail to get the c of g right and it was then too heavy, it never flew successfully. However, although I used the wings and tail on other projects, I still have the fuselage! Having got hold of the plan I will build a new wing and tail and see if after all of these years I can get it to work, using either a Cox .049 or one of my vintage 0.5 diesels. So much to do! (Sorry the printed pages have finished up on their sides, I hope you can read them)!

[Colin Leighfield]

Hi Gonzo, thanks for putting that up, it rings bells. Also it confirms that Stewart Uwins was using that engine in his contest winning rudder only plane. The vibration was definitely a problem with reeds and one of the mags found this problem with their Jackdaw, which I also recall they had converted to have a tricycle undercarriage! I think though that a decent 29/35 category two stroke glow motor is the right choice for this plane, as you are suggesting..

[Peter Christy]

Gonzo: Yes, the plan actually shows a Frog 3.49! My recollection of Frog engines was that they were all prone to vibration. Indeed, IIRC, one was actually called the "Vibra-matic" - and with good reason!

My Super 60 was originally owned by a friend who flew it on single channel with a Fred Rising escapement. Powered by a Frog 500, it could barely climb, and required an almighty heave to get it airborne! Having nearly dislocated my shoulder trying to get it airborne one week-end, I asked him if he had any other engines. "Only an ED Racer!" , he replied. Once fitted with the Racer, it went up like a homesick angel!

When my friend emigrated to Australia, he left me his Super 60. I fitted it with a Merco 35 and a Grundig 6-channel radio, and had a lot of fun with it, until an argument with a barbed wire fence led to its demise!.

The Super 60 is an excellent model. My argument is with those who seek to improve it by adding ailerons, reducing the dihedral, etc. All this does is produce a model inferior in every way to the Jackdaw!

Colin: Some interesting extra background there! Its good to know I'm not alone in appreciating the virtues of this much-over-looked model!

--

Pete