|Ashley Hunt||25/02/2020 16:51:42|
|26 forum posts|
I’m in the process of building a Puppeteer from a kit that I bought back in the 80’s. I’ve been reading some of the past threads on these models and the impression I get is that to get the balance correct an amount of lead has to be added to the firewall. I’d like to fit an equally old Laser 60 four stroke but it’s quite a lump of an engine and to be able to use it I’d have extend the cowl forward by quite a distance. Although this would probably negate the use of any additional lead. I’m sure this is a common problem so does anyone out there have any thoughts ?
|john stones 1||25/02/2020 17:01:29|
11704 forum posts
Personally, I would proceed as planned, if you can live with the altered look who am I to disagree.
|67 forum posts|
I have recently finished a Flair Pup, bought via the classifieds on this forum, along with a Saito 62. I was advised by an ‘expert’ to shove the nose out by maybe as much as 40mm to overcome the tail heavyness. I finished up streching the nose by 25mm which proved perfect to accomodate the rear carb and along with a Dubro four stroke linkage did the task admirably and i’ve finished up with the C.G. spot on with no additional nose weight required. I have had a Mk1 kit unbuilt for donkeys years having started one wing panel but not proceeding any further. This proved very useful during my later build as i robbed the cowl and cabane struts, both of which were of very poor quality and pretty much unuseable. I also had a set of decals and my word,they were awful. I used a few items but the wing roundelsi found hopeless...maybe just me, but i now have all the necessary paint to complete the task. My model is still unflown but looks very pristine and will i’m sure be fine once i bight the bullet. Had a few health problems recently but hopefully this coming summer i can fly the thing. If i knew how to create an album, i would post some pictures. I have several of my nose extension which was easy. N.B The models nose extension, not mine!!!
|Jon - Laser Engines||25/02/2020 19:04:11|
|5632 forum posts|
My Dad taught me to fly on one of these and i have flown 3 since.
My thoughts are as follows.
Dont over power it. A laser 61 or 62 is the absolute maximum it needs however, you will struggle to fit either without major mods..more on this later.
Dont worry about the nose weight. You could add 5 lbs and it would still fly fine. My Dad balanced his as the plan with an OS48 surpass for power. It flew ok but he added more weight to give about 1lb on the firewall. I have flown others balanced per the plan and it needs the extra nose weight.
If you have the Mk2 kit forget installing either of the Lasers. As much as it pains me, it aint gonna happen as they designed it for a 2 stroke 2nd time round and the design is not very flexible. If its the earlier kit then it can be made to work but its messy as the engines are much longer than there is space for. You could make the nose longer, but its already much longer than it should be and it will look very strange. I would shorten the nose a bit for scale looks, then mount the engine further back. The tank would then end up over the wing. Even if you leave the nose at the kit length fitting a laser 61 would be very difficult. The 62 would not be so bad as its a smaller engine physically but it would still be difficult to fit everything in and you would still need to move the firewall and mount the tank over the wing. Getting exhaust and cooling air out would also require a redesign of the whole front end and undercarriage mount.
Even using the shorter OS48 my dad moved the firewall back by over an inch when using the standard nose as it came with the kit so mods are needed no matter what you do.
|stu knowles||25/02/2020 19:46:39|
|615 forum posts|
I have owned three Puppeteers over time. All have been powered by 2 stroke motors, the last a way overpropped OS 50max which was about 30 years old.
The engine was mounted by the backplate bolts which kept it snug to the firewall. It started with a small amount of lead in the cowl but this fell out at some point and it flew just as well with the c.g well behind the plan point.
I would say build as per plan except make it quick to rig as you build. Do it as plan and it takes ages to assemble and strip. If you have the right car it might go in in one piece.
I had a Pug 405 estate which took the fully assembled Pup' When it was changed to a 407SW the Pup never saw the field until the car was sold again. I made sure the next car would take it in one piece.
It was my favourite model for a long time and spent a fair amount of time with the Flair vintage floats flying off water and snow
649 forum posts
As I've posted elsewhere, balance the plane with the nose pointing down -as described in the instructions (yes I agree it is silly). I balanced mine exactly on the spot with the plane level at flying angle, I was lucky to get it down in one piece, it was very unstable. Had to add 8oz of lead in the cowl. How Stu managed with a rearward CoG I don't know but he clearly did, but mine was virtually unflyable until lead was added. I had a 70FS on the nose too.
|Ashley Hunt||26/02/2020 00:15:51|
|26 forum posts|
Thanks for all the replies, the suggestions are all really helpful. I’ll keep going with the Laser 61, mount it on the existing firewall and see how it balances out. A rough measurement suggests that I may have to push the nose out by somewhere between 25 and 35 mm. I’ll also make sure to balance it nose down. I’ve kept the kit and engine for so long now that it would seem wrong to not put them together !
|David Davis||26/02/2020 06:02:17|
3851 forum posts
I've had two Puppeteers and a Baronette all powered by four stroke engines. To preserve the looks of the cowling I cut a huge hole in the firewall, bigger than the size of the entire engine, then mounted the engine on a 1/4" ply plate which was then screwed and glued to the back of the original firewall, stood off by hardwood bearers which were about 25mm thick. Shame I didn't take a picture of it.
I concur with everybody else's opinion about the cg position on the plan, it's wrong! Both of my Puppeteers required considerable amounts of lead to be bolted to the cowling to get the model to fly properly.
|Mike Bell||29/02/2020 18:31:13|
302 forum posts
20 odd years ago I built a Puppeteer and installed a Laser 70 (I think) and it is currently fitted with a Laser 62. To make the engines fit without extending the nose I cut into the firewall, to allow the back of the engine to sit partially behind it. The engine is mounted on hardwood bearers.
One other piece of advice I would give is to blank off the front of the cowl so that the air only goes over the engine and not around it. I cooked the Laser 70 as a result of not doing this.
|Ashley Hunt||29/02/2020 19:20:29|
|26 forum posts|
Thanks for that latest reply Mike. Several people have now suggested cutting into the existing firewall to avoid extending the nose of the model which is something I’ll now do. Can you remember what size tank you used with the Laser 70 engine, did you use the one supplied with the kit or a larger one ? When you say blank off the front of the cowl presumably you then had to cut a section out of the cowl to get the air over the engine.
|Malcolm Fisher||29/02/2020 20:03:19|
653 forum posts
I bought a second hand Puppeteer some years ago. It came with Futaba radio and is powered by an OS 40 two stroke. I assumed that it had been set up properly and just flew it as it came - never had any problems apart from, as has been said, the time needed to rig it for flight. Last time out I assembled it at home and it went into my estate care with no difficulty. Sadly I no longer have access to a site where I can fly power models so if anyone is interested and cares to make a reasonable offer I am prepared to sell it - buyer would have to collect.
|Martin Harris||29/02/2020 21:12:43|
9560 forum posts
I'd expect that Mike was referring to blanking the majority of the cowl opening, Ashley.
These big open cowlings look as though the engine is bathed in copious amounts of fresh air but what actually happens is that air flows via the easiest path it can find, which leaves the engine in a pool of steadily heating stagnant air. It then starts to lose power and unless throttled back and allowed to cool, stops.
A clubmate with a Flair Harvard suffered from dead sticks on every flight and after weeks of poo-pooing the idea, eventually acceded to my suggestion to make a dummy engine to block off all but the area in front of the real cylinder - result was reliable running. You also need to ensure that air can get out of the cowl after passing through the cylinder and head fins...the usual advice is two to three times the inlet area although opinions vary.
Edited By Martin Harris on 29/02/2020 21:22:16
649 forum posts
When I built my Puppeteer I cut back the bottom wing centre section as far as the main spar and put the retaining dowels into it. That meant that the fuselage was extended further back such that the undercarriage was permanently fixed in place (saving 4 screws). One nylon screw was used at the back of the lower wing to retain it. As the leading edge strength was lost at the centre I beefed up the main spar to compensate
Four nylon screws held the top wing (I couldn't think of a secure way to cut it down to 2.
The outer struts were held using press-studs, like the Avicraft Panic. One half was soldered onto the brass wing brackets and the other epoxied to the strut. Never had any detach in flight.
So total 5 screws and 8 press-studs, it brought assembly down to less than 5 mins at the field.
|J D 8||29/02/2020 22:28:47|
1630 forum posts
On my Major Mannock the top wing was held by 4 saddle clamp's and 8 screw's, a right pain.
Now two nylon bolts through a holes in plate soldered to the cabane at the rear and two piano wire hooks attached to the original saddle clamp fixings on the wing then pass under the front cabane cross wire [ a little tape prevents wire to wire contact] hold the wing in place. So now only 4 bolts to fit both wings.
Edited By J D 8 on 29/02/2020 22:30:04
|Richard Acland||29/02/2020 22:49:00|
141 forum posts
I dont think you need to overpower this model if you want it to fly at a scale speed. I remember the original instructions by Dudley Pattison when I built mine using an OS 48 fs. They said get the Cof G right even if you have to put the Church roof in the nose. If you build the rear end nice and light you dont need that much extra weight in the nose. As said previously a .60 would be at the top end power wise.
|Martin Harris||01/03/2020 01:00:28|
9560 forum posts
An OS 40 Surpass [with no discernable compression!] was perfectly adequate for scale performance in mine. It's been in the loft for a few years - I really should give the old girl an airing for old time's sake...
|Low pass Pete||01/03/2020 09:07:59|
272 forum posts
Mine had an OS52 Surpass. Perfect powerplant but it did need some small mods to the firewall.
Edited By Low pass Pete on 01/03/2020 09:08:27
|Mike Bell||01/03/2020 14:31:42|
302 forum posts
Hi Ashley, as Martin suggests I fitted a disk of lite ply in the front opening of the cowl then cut out a segment from it directly in front of the cylinder head. I covered the front of the ply disk with a photo of a radial engine which actually looked OK from a distance.
The tank was a Slec item, either the blue or red. It was a neat fit between the bearers and gives plenty of run time.
|John Bisset||04/03/2020 20:27:42|
|233 forum posts|
This is a most interesting & timely thread since, like Ashley, I am building a Puppeteer which I bought probably in the mid to late 80s. I restarted work on it about three weeks ago after several years gap due to house moves etc. So far I've built one set of wings and the tail, so the fuselage is next.
Not sure whether it is a Mk1 or Mk 2 kit - how do you tell? The instructions, written by Dudley Pattinson, do mention some 'minor alterations' in the kit, so possibly Mk2.
I am intending to fit an electric motor, so was wondering about weight & balance and possibly extending the nose. Any comments/thoughts on this?
Thanks i12fly and J D 8 - the rigging modifications you suggest sound useful for storage, though I hope to be able to leave the machine at my local airfield much of the time.
|Don Fry||04/03/2020 20:59:32|
4557 forum posts
I've built a number of the "scout " series. A common theme, is an over engineered back end, and heavy wood. Lighten the back end, and it ceases or, at least decreases,to be tail heavy. How heavy/strong does a backend need to be. Lose a bit of weight at the back, loose a lot of weight at the front.
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