Seagull P-47

[Joakim Karlsson 1]

Looks good.
Many thanks for the info!

[Bruce Collinson]

Tim,

This was the post I was looking for re the cowl fixings. If you can be bothered to send a close up pic I’d be most grateful. Your thread has got me seriously interested, I have recently bought a Laser 100 and like all modellers, I’ll have to attempt a warbird at some stage. I formed the impression from surfing that it is arguably the most benign warbird for a relative beginner, in terms of nosing over, tip stalling and general treachery. Would you agree?

The modifications to the u/c, tank mounting etc are most helpful. Is it still flying well?

Look forward to your reply!

BTC

[Tim Flyer]

Hi Bruce sure no problem. Yes this is actually a “kind” Warbird plus it looks good! It isn’t hard to fly but still use reduced elevator rates and ideally none or very little expo etc. In view of potential nose overs I modified the cowl fixings so minimal damage occurs to the cowl. One big tip for cowl fixing is plastic screws. I use m3 plastic screws threaded in to “threaded inserts “ sold by RCWorld and Model Fixings. Plastic screws minimise damage , wear and stay tight as they do not resonate with IC engines. I’m surprised so many modelers use metal screws on cowls. For instance many plastic/glass motorbike fairing and car body spoilers use plastic fixings for their non resonating properties and not because of cost! I will send photos tonight,

[Tim Flyer]

By the way yes it’s still flying well thanks. The Laser 100is perfect in it .i use a 15x8 prop. Hopefully it will be out tomorrow 😊. I prefer to fly when we have wind straight down the strip ideally 5-20mph max . A bit of wind helps smooth take off and landings

[Tim Flyer]

[Tim Flyer]

I hope that helps Bruce. Enjoy it . It’s a great plane!

[Bruce Collinson]

Tim,

It does indeed, thanks very much. It also illustrates the dummy radial engine and I deduce that this is an effective blanking duct for airflow over the head and exhaust. M3 inserts ordered, but from Fleabay as no stock elsewhere.

It's seriously tempting as a first warbird but I've three other projects which are far from wrung out to dry first. Maybe Christmas ... btw well done for smuggling it ont o the kitchen table for the pics!

With kind regards,

BTC

[Joakim Karlsson 1]

Very neat installation.
How does the Laser fare being inverted?

Also, I have an older version of the Laser 100. Should I bother installing a pressure nipple on the exhaust?

[Jon H]

Posted by Joakim Karlsson 1 on 25/10/2018 11:52:05:
Very neat installation.
How does the Laser fare being inverted?

Also, I have an older version of the Laser 100. Should I bother installing a pressure nipple on the exhaust?

If you lower the tank as Tim describes it will be happy as a clam. Pressure is not required and not recommended

[Joakim Karlsson 1]

Thank you Jon!
I really should read the whole thread before asking questions now shouldn't I?

[Tim Flyer]

Cheers chaps I flew it again yesterday. Its quite a joy and very well behaved it is really smooth plus easy to land. I must admit that i find a but of wind (5mph plus)down the strip helps slow it down on landing

I also helped my club mate Nick set his up at the field. He had a number of issues that needed sorting (he hadn't finished balancing it and the throttle connection was poor and various servo linkages were also wrong, and by the time they were fixed we didn't manage to get it in the air as it still needed a few tweeks.

I guess all reading this are experienced modellers but its always worth mentioning that in a good set up 100% of servo travel should give the correct full deflection of control surfaces. If it gives too much deflection then the clevis should be moved inwards on the servo arm to reduce movement. Reducing movement just by moving end points/limits on a transmitter will spoil control sensitivity. This also applies to the throttle. If you have a nice full movement the plane will be far easier to fly. There is no point using the outer arm of a servo and setting limits so just 20% of servo travel is utilised.

Hi Bruce np yes sneaked it into kitchen late at night . YesI showed the front to show the cut out baffle that works well. The flimsy front dummy radiator was epoxied in and then the rear was sealed and reinforced with copious amounts of gorilla glue that foams up nicely and keeps it semi rigid.

Hi Joakim Thank You. I also put an extra bit of birch ply reinforcement on the bottom of the engine box and glassed it inside. Where the fuel pipes go through the bottom bulkhead I stuck with silicone bit of plastic to prevent carburettor spit getting inside the plane(silicone caulking means its easily removable but still fuellproof). Regarding pressure feed none needed as Jon says. The Laser is great inverted. I make sure I give it a good prime by blowing down a silicone tube into the vent and slowly turning the engine over. It normally quickly flick starts on a backward flip . Otherwise it quickly comes into life with a starter. Nicks new Laser 100 Engine started first flick inverted yesterday and we soon had it running beautifully. Another club buddy Ron was flying his Laser 70 and asked the same question as he dead sticks when inverted. The answer is simple!! Lasers don't care and don't know what way up they are they run the same....HOWEVER the FUEL TANK does. What Ron had done was use a too long clunk that wedged at the back of his thank. That meant that initially inverted flight was fine, however later into the flight when fuel levels fell the clunk was stuck on the wrong side of the tank and sucked air when inverted. Its important in clunk tanks that the clunk can move freely, otherwise the "halfway through flight deadstick will occur"
 

Edited By Tim Flyer on 26/10/2018 11:39:04

Edited By Tim Flyer on 26/10/2018 11:39:35

[Bruce Collinson]

Tim,

All very useful. I'm definitely interested in this as a first venture into warbirds but it will be next spring at this rate.

You were lucky with the weather, too windy here.

Jon is quite consistent, get the tank right and a Laser will start and run. We're mass building a 25 yr old F3A patternship which I hope to fly with an ASP 91, otherwise my Laser 100 may have to go in though I was saving that for another patternship I bought recently. Too many projects ...

BTC

[Tim Flyer]

Happy to be of help Bruce . The pattern ship sounds fun. Yep so many projects I know how u feel! Jon’s advice is always spot on and he has really helped me turn what was “impossibly difficult “ into “flying fun” with Warbirds.

[Tim Flyer]

Had a couple of great flights today with the P47 . The wind was gusting above 20mph but it handled superbly. With all the recent rain I had to have a helper giving it a shove to start the take off run on our grass strip otherwise it would stick and nose over . Landing was perfect, nice and steep into the wind with full flap. I really enjoy this model. The laser 100 is just right in it . I think it’s designed around 20cc petrol but the 100 really does think it’s a 120 and turns the 15 x 8 prop at a very good rate ( I haven’t yet tacho’d it yet). Here’s a picture of it coming in 😊

Edited By Tim Flyer on 17/11/2018 21:45:21

[Bruce Collinson]

Now even closer to commitment ... Joakim, is yours finished/flying? Irritatingly both the retracts and oleos are showing as out of stock.

I think I've got the whole list of mods committed to memory: usual front end reinforcement and retract mounts; double check the cowl length; Robart 3" wheels with retracts angled forward c. 1/8" packing; nylon M3s for the cowl.

BTC

[Joakim Karlsson 1]

I haven't even bought mine yet
Had some trouble deciding between Seagulls 60-sized P-47 and VQ new P-47 in 40-50 size.
I'm quite fond of both manufacturers. But I have a Laser 100 and a bunch of PowerHD 6001MG servos, already, so it looks like it'll be a Snafu soon enough.

[Bruce Collinson]

Well it's in build, wings fairly easy and a good fit, slight trimming needed to the servo arm slots but trivial. Tail left well alone till engine and tank in. Stared at pushrods and nylon tubes for half an hour then twigged that there's a third pushrod slot formed by the hatch cover, so servos can go in easily, after more re-gluing and some skinning epoxy inside the fus.

HK seem to be ambiguous re the retracts and their website is so clunky. Could have mended my Wot 4 (again, Darwinian issues re aileron direction) in the time it took to realise that there are several versions nearly identical so had to go back to this thread yet again. Wise heads down the club all concur, beefy servos and use the supplied retracts. Am pondering. Are your oleos telescopic/sprung? If this seems naive, this is a first warbird and first retracts for me but indirect experience shows a seemingly limitless potential for bending and ripping off with greatly graver consequences than a couple of nylon bolts and the odd plate rebuild.

I'm treading carefully.

Was about to drill engine mount holes then remembered the warning re the cowl dimension so that's to check first.

BTC

[Jon H]

Oleos vs wire legs.

Wire legs are better if you are likely to plant the model hard as they tend to deform and minimise the damage to the aircraft. However, warbirds tend to have long legs and so wire legs are also wobbly which means that takeoff can be a little more wayward, and even a good landing is likely to end in either a bounce or a nose over. The bounce is caused because a wire leg will move aft due to the drag of the grass. This makes it longer (assuming it has a slight fwd rake) and pings the model back into the air.

Oleo legs absorb this load as they can get shorter by design. The trick is to land well enough for the load to go up the leg into the spring and not backwards. If its backwards you effectively have a 12mm ali rod stuck out of the wing with no give in it at all.

Personally, i would always use oleos and improve my landings. The P47 is pretty good as warbirds go but if you have another model you know well practice landings with it for a flight or two. When every landing is the same, with the same touchdown point etc then its time to think about the P47

As for servos, it needs nothing more exciting than standard 148's or whatever. No need to go mad

Edited By Jon - Laser Engines on 18/03/2019 17:09:32

[Bruce Collinson]

Very helpful Jon. Oleos it is.

Is Tim's tank tight to the underside of the plate rather than sitting on the bottom? Preliminary squinting suggests it will strap onto the plate via the helpful cutouts and still line up quite well with the spraybar.

Also, the manual is silent on flap angles. Does c. 10 deg takeoff and full flap which looks to be c. 40 deg landing sound about right?

Did wonder whether to cheat slightly, leave off the silencer and use the flexi which came with the Laser, smuggled out well to the rear of the cowl, but will it need extra vent exit holes anyway?

BTC

[Tim Flyer]

Hi Bruce here is the link to my assembly photos. The tank does just strap with zip ties underneath the tank bay floor with the engine as per my photos between 7 and 8 o clock it’s perfect. The standard laser 100 muffler is also perfect length to just poke through the cowl.

Please see photo album on this link

**LINK**

[Bruce Collinson]

Tim,

small favour, would you check the distance from the firewall to the prop driver as I’m not achieving anything like 145mm per the manual. Nearer 130 I reckon. Save me making surplus holes in the firewall and cowl. Insert emoji of choice here.

BTC

[Jon H]

I never use flap for takeoff on my warbirds. I like to have the airframe clean with the minimum of drag. Its also another thing to have to faff with on climb out after takeoff and you really dont want more things to worry about on the maiden voyage.

Another thing that can be helpful is to practice putting the gear up and down. By that i mean that if you arent used to flying with retracts trying to remember where the switch is in a tight spot can divert your attention from flying the model. Again, you you can practice this with your sport model if its not got retracts, just flip the switch anyway until its 2nd nature and you dont have to look for it.

Its important on the maiden to get the wheels up quickly but only if the model isnt a bucking bronco. If its a handful, the gear can wait, if not then get them out of the way.

On my models i have the gear and flap switches in the same place so that each model is identical. I have seen guys in the past who have each model set up differently and coloured tags all over the radio so they can remember what does what.

One final thing is eventualities. Have a plan in your head already for what to do in case of XYZ. For example you suffer retract failure and they are stuck up, or only one comes down. It happens, dont worry about it. My plan for this is to put the one leg away if it came down, then do a normal approach with flap down and little extra speed. Once i am sure to make the runway i kill the engine, drop to about an inch off the floor then flick the flaps up. This stops the flaps being broken and protects the prop. The loss of lift also drops the model pretty firmly to the ground to prevent stalling.

Engine failure is a similar thing. Firstly, LEAVE THE GEAR UP! less drag means more glide, and if you have to put it in the field a belly landing is usually a better bet. If you are totally sure you can make the runway leave the gear up until the last moment to keep your options open

[Bruce Collinson]

Very helpful as ever Jon. Identical switches is a lesson already learned, though having just switched radio gear it's a work in progress!

Landing flap? Max?

BTC

[Tim Flyer]

Hi Bruce . I’m pleased you are getting on with it ok . Regarding the firewall to prop gap I can measure mine for you tonight. However with this model the spacing should be relatively easy to do by “eye” as there is no spinner back plate to cowl distance to worry about. From memory I think I allowed about 1cm of clearance between propeller and the cowl sides. The most important thing on this model is that the cowl is fixed in correct position first. If you are worried about that you could tape it instead. Then you can measure the distance you need with a ruler. What I suggest as I did it myself is reinforcing the cowl mounts and fitting first. Leaving a full 1cm gap between backplate and cowl leaves a bit of error margin too.

[Jon H]

On my 'heavy metal' warbirds i use about 60 degrees but as this is lighter you may need a little less. If you have the option of a slider on your radio set it so you have 60 available and then just feed it in. If it feels like too much then bring it back and measure it all once on the ground.

In general, if the model balloons up you either have too much flap, or most likely are flying too fast. All of my bog models suffer nose drop with flap down.