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Jun 27, 2015, 06:10 PM
What could possibly go wrong?
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Build Log

Ivan Pettigrew's Lakemaster


This plane is a distillation of Ivan's design principals, smaller than nearly all of his other models. It is lightweight and strong. Once set up it is a very sweet and gentle flyer and also capable of impressive loops, rolls, stall turns, inverted flight and all that good stuff. I trust mine enough to use it as a camera platform and my flying skills are only just intermediate. It's a good plane to practice on.

If you're looking for a water plane to fly from dry land as well, to build from plans, classic balsa construction, electric power and small enough to fit in a 2 door car. look no further.

At the time of writing, the plans are not quite ready for distribution yet, keep an eye on the Ivan Pettigrew Planes Thread. When you get started, you will be welcome to post your build shots, questions and suggestions here.

All contributions gratefully received.

Cheers

Nick
Last edited by nickchud; Jun 28, 2015 at 05:04 AM.
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Jun 27, 2015, 06:23 PM
What could possibly go wrong?
nickchud's Avatar
I started with the fuze. Ivan suggests building it by cutting out the side panels from 1/16" balsa first, then installing the longerons before finally fixing the 2 sides together. I built the frame first 'cos I find that approach easier for getting the servos in and connected.

Last edited by nickchud; Jun 28, 2015 at 05:06 AM.
Jun 28, 2015, 04:21 AM
What could possibly go wrong?
nickchud's Avatar
To convert Ivan's model to a twin I used 2 of these motors. because that's what I had already. They are 2200Kv and they weigh 34 gms each. I would recommend a Kv of 1800 but I have used what I've got, with 7" x 4" props and a 3S1P battery. I never let the throttle near the top, could probably set an end point on my Tx at 60%. After a 6 minute flight I found that I had been drawing an average of 75 watts, which would give a 20min flight with plenty to spare on my 1800 mAHr battery.

Jun 28, 2015, 05:02 AM
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nickchud's Avatar
Setting up has been straightforward. I have installed a gyro on the ailerons and she flies well even in pretty windy conditions. This video shows a range of different flights.

Overall, very high on the fun-to-fuss scale!

Produce 7 (8 min 16 sec)
Jun 28, 2015, 06:03 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Ivan told me about this project back at the start of the year and sent me the basic specs with a challenge to design "an easy build seaplane for fliers with some experience".

We swapped drawings and worked separately on our interpretation of the basic parameters: this is what he said:

Hi Mike. (Nov 2014)
You asked about the flying boat that I plan to design. With more interest in our area in float flying this idea. I challenge people like this build something, but what is needed if an easy build, user friendly model. The best thing I can suggest is the Puddle Master that was a kit put out by Ace years ago. The other thing fellows have noticed is what I have always pointed out that land planes converted to float models, especially high wing designs like Cubs, turn over in water when any wind is blowing if they try to turn and taxi downwind. Water handling with flying boats in any kind of wind is so much safer then with float planes. For the same reason, the dihedral in the standard wing of the Puddle Master that has so much dihedral is not a good thing in a flying boat when there is any wind.
Although the Puddle Master flies pretty well, there are improvements that could be made, so I plan to design an easy build model about the same size, with straight non tapered wing and flat bottom hull like the P Master. The things about the P Master that I think could improve it are taking out most of the dihedral in the wing and adding ailerons, making for four channels instead of three. The wing section could be thinner. It is very thick with no Phillips entry, so the glide angle is steep and it bobs around too much in turbulence. I will add a secondary step and raise the stab part way up the fin like a Catalina because it is in the water too much. I think we will call the new model the Lake Master. I hope to have the prototype flying early in the Spring, probably with a Park Flyer 400 outrunner.
The size I am looking at is span 46” and length 41. The original Puddlemaster had a span of 48” and was rather short at 36.6 ins.
Here is a scan of my rough drawing at 1/5 scale so it fits nicely on one sheet of paper. Full size copies would be on 24 inch paper with wing and stab on second page. Tip floats are still to be done.
Some comments: Span 48” Length 39” Wing area 363 sq.in.
Target weight with 3S 1300 battery and Park 400 motor, 28 oz for a wing loading of 11.1 oz/sq.ft. Prop 9x6.
Fuselage will be 1/16 in sheet with minimum bulkheads and longerons about in at corners, rounded on after section top and bottom.
The top of the fuselage from the leading edge of the wing to the stern is a straight line and can be considered the datum line. The fuselage can be built upside down on the bench.
A wing section like the Selig 7055 has a flat bottom from the spar to trailing edge. If this sits right on the datum line, the Phillips entry raising the leading edge slightly will give about 2 degrees of incidence.
The stab ribs will be wedge shaped, so that if the bottom surface of the stab is on a mount that is parallel to the datum line, it will give about 1 degree negative incidence.
The extended lower section of the rudder serves as a water rudder. I did not slope the rudder post backwards because I wanted the tip of this water rudder to be as far back as possible.


With the results you see!

We both noticed that when trimmed to fly level with power on, as soon as the power was cut, our models climbed excessively., probably due to the relatively high airspeed over the upper surface of the tailplane from the propwash, causing unwanted lift.

Anyway, a bit more upthrust was one answer, or raise the tailplane up the fin somewhat was another.

Mine crashed terminally at Comox at the far end of an outside loop, but the replacement is 90% complete.
Jun 28, 2015, 08:09 AM
What could possibly go wrong?
nickchud's Avatar
Super contribution Mike! I don't really like those raised pylons and so I went for a twin instead. OTOH, Ivan's Seagull has proved itself over the years. Also there are quite a few similar arrangements on gliders and on the bird planes thread. Maybe the longer tail reduces the effect of propwash over the top surface of the rear stab.

Jun 28, 2015, 08:42 AM
Wanted for breaking Ohm's Law
Dennis Sumner's Avatar
Looks nice Nick.

I like the twin over the pod design too, I imagine the twin was easy to trim and shouldn't have trim changes with power on or off.

Denny
Latest blog entry: RC Throw Gauge
Jun 28, 2015, 04:11 PM
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nickchud's Avatar
Yup, you're right. The only problem I had was that there was way too much power until I got used to it. Not bad, considering that the extra motor, prop and larger battery only added 3 oz to the All Up Weight.

Jun 28, 2015, 04:23 PM
Wanted for breaking Ohm's Law
Dennis Sumner's Avatar
You could have went with smaller motors....anyway I bet it sounds and looks pretty nice!

Denny
Latest blog entry: RC Throw Gauge
Jul 04, 2015, 03:18 AM
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nickchud's Avatar
I think I'm going to try and build a Seabee, using Ivan's basic plan, with some changes.

Jul 23, 2015, 02:43 AM
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nickchud's Avatar
Ivan now has version 2 of the LakeMaster flying.

Super job, again.

Jul 23, 2015, 04:21 AM
71% of the world is runway . .
Bart83's Avatar
Hi Nick ,

That is a fun idea , i've always had a thing for the seabee. The Robbe Seabee foamy was my re-entry in this hobby back in 2009.
A while back i started work on a new Seabee design but never finished it , all the round shapes make it difficult. This would be a perfect model for a full composit build. . . . Ah so much idea's o little time


Video from ''09 (dont mean to hijack your thread , just getting excited a bit ;) )

Seabee (1 min 54 sec)
Jul 23, 2015, 05:11 PM
What could possibly go wrong?
nickchud's Avatar
Well, it's only an approximate likeness to a Seabee. I was trying mainly to stick to Ivan's plans but with the use of a Seabee-like pusher as another alternative to the original pylon idea.

As you say Bart, that funny shaped nose is not easy to do with balsa. I've been making it up as I go along, with quite a bit of trial and error. Let's hope it flies as well as my foamie Seabee does.



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