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Author Topic: foamboard electric trainer by Bob Hunt?  (Read 503 times)

Offline Brian Courtice

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foamboard electric trainer by Bob Hunt?
« on: January 14, 2022, 08:33:44 PM »
Is there a plan and/or a build article for this nice looking foamie stunt trainer anywhere?
https://www.theparkpilot.org/ControlLine0208


Online Mark wood

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Re: foamboard electric trainer by Bob Hunt?
« Reply #1 on: January 14, 2022, 10:27:09 PM »
Looks pretty simple to just cut by hand. Our local FF club which 50% are also part of our local CL club have secured an indoor flying sight and I have finished cutting several of Igor Burgers  Indoor GeeBee models. We are going to be doing lots of flying soon. I'll post some information on our activities when that happens including a build thread.

Igor's model

https://stunthanger.com/smf/gettin-all-amp'ed-up!/early-christmas-)))))/
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Offline Brian Courtice

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Re: foamboard electric trainer by Bob Hunt?
« Reply #2 on: January 15, 2022, 07:41:18 AM »
I think I could draw a plan from that picture. Is that about 250 sq in?


Motorman 8)

Yep it should be pretty simple to copy. . All I really need is the wingspan and specs on the motor.

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Re: foamboard electric trainer by Bob Hunt?
« Reply #3 on: January 15, 2022, 08:16:02 AM »
Yep it should be pretty simple to copy. . All I really need is the wingspan and specs on the motor.

Or maybe send Bob a PM. He's a nice guy to talk to and is super helpful. If he has a pdf of the plans, he'll likely send it to you.

I just sent him an email.
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
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Online Bob Hunt

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Re: foamboard electric trainer by Bob Hunt?
« Reply #4 on: January 15, 2022, 10:26:13 AM »
Hi Guys:

Dick Sarpolus used to come up to my home with his fleet of foamies and we would spend the day in my back yard flying them. At that time I had a column in AMA's Park Pilot magazine dealing with small CL foam board planes. I told Dick that we should co-design a model that could be presented in that rag as a construction feature. He came up bright and early one morning and we put a clean sheet of paper on the old drawing board (yes, that's how I still design my planes...) and started laying out a model that had looks similar to a Bearcat. We called that model the Park Cat. After the drawing was done (about fifteen minutes...), we started cutting the Depron foam, plywood, and spruce parts for the model. It was all glued together with 5-minute epoxy in about an hour, and then we installed the motor, ESC, Hubin timer, and  battery. We ended the day by test flying the ship, and it was a total success. I was able to do the entire pattern with the model and even lay on my back and do square overhead eights. In fact, that model would - and still does - perform any maneuver I could think of and do it with pretty good precision. I still fly it often in the back yard.

Plans for that model should still be available from the AMA plans department. If not, I have a PDF of it. Please check with AMA first because it is their property.

Later - Bob Hunt



Later - Bob Hunt

Offline Brian Courtice

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Re: foamboard electric trainer by Bob Hunt?
« Reply #5 on: January 15, 2022, 02:50:41 PM »
Thanks Bob!
I'm not surprised to find out that Dick Sarpolus had something to do with it. Everything Dick designs is simple, elegant, good looking, and perfectly suited to it's intended purpose.
I can probably manage to sketch up something pretty similar.
If you wouldn't mind, could you measure the wingspan, and have a look at exactly what motor was used?

Offline Brian Courtice

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Re: foamboard electric trainer by Bob Hunt?
« Reply #6 on: January 15, 2022, 03:11:33 PM »
A quick google search for "Dick Sarpolus 1/2A" yielded an article for a very similar R/C design by Dick (with a PDF) for a blue foam version.
https://www.theparkpilot.org/akro




Offline Dennis Toth

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Re: foamboard electric trainer by Bob Hunt?
« Reply #7 on: January 15, 2022, 03:12:41 PM »
Brian,
If you want something a little bigger here are the plans for an Aussie design call the Yardstick. It is a flat plate wing around a 15 -19 size engine and would also be a great electric.

Best,    DennisT

Offline Brian Courtice

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Re: foamboard electric trainer by Bob Hunt?
« Reply #8 on: January 15, 2022, 03:25:55 PM »


Plans for that model should still be available from the AMA plans department. If not, I have a PDF of it. Please check with AMA first because it is their property.

Later - Bob Hunt

Do you recall what the name of the model is, so I can search for the plan? Thanks again.



Later - Bob Hunt
[/quote]

Offline Brian Courtice

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Re: foamboard electric trainer by Bob Hunt?
« Reply #9 on: January 15, 2022, 03:38:13 PM »
I think I may have I found it.
The AMA plan is called the Foamy Skyraider.
The planform is different but the construction looks the same.
There is a free copy of the construction article here:|

https://plans.modelaircraft.org/wp-content/uploads/pdf/MA00980MA1.pdf

« Last Edit: January 15, 2022, 04:25:34 PM by Brian Courtice »

Offline Brian Courtice

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Re: foamboard electric trainer by Bob Hunt?
« Reply #10 on: January 15, 2022, 04:20:20 PM »
Brian,
If you want something a little bigger here are the plans for an Aussie design call the Yardstick. It is a flat plate wing around a 15 -19 size engine and would also be a great electric.

Best,    DennisT

That looks great. I think I want to start with something a little smaller.
I've been an R/C flyer for almost 50 years, and I have tons of unused electric gear laying around.
Haven't flown control line in many years. I want something small and cheap to start out as I fully intend to destroy it learning loops eights and inverted flight as quickly as possible. :) I'm a pretty advanced 3D pilot, so we will see if my R/C skills will help me learn faster.

Offline Dan McEntee

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Re: foamboard electric trainer by Bob Hunt?
« Reply #11 on: January 15, 2022, 05:38:49 PM »
    I have np doubt that the airplane you are looking at is everything that Bob says it is and does, and has the advantages that electric can bring to the table for learning the pattern. But you have to ask yourself, is that all you want to do with it??
   I volunteered at the KidVenture C/L circles for 16 years and about half way through that run, we were starting to run out if airplanes that could take the Timex Test, take a licking and keep on ticking! Bob Arata and I used to spend the long ride home talking about what to design and build, and the first thing that came to my mind was, I did NOT need to be capable of stunting, and that it had to survive a one point, Lawn Dart Landing in the hard ground at Pioneer Airport! We also decided that as few parts and components as possible were from the hobby shop because they are quickly vanishing from the face of the earth, but Hardware and Building Supply Stores are all over the place. We came up with our TuffBaby trainer that was built from Core-Plast plastic, yard sticks, and bamboo BBQ skewers and is designed as a Primary Flight Trainer. You can probably find out a lot about it by searching the forums here because I know I have typed out the story many times, and the plans may be in one of those threads, and if not, PM me and I will send them too you. The TuffBaby or (Tough Baby) was first introduced at Oshkosh in 2010 with 5 models and I think at least 4 of those are still in service, with the 5th once having had the flying surfaces replaced, which is one of the primary features of the airplane. It has a more or less indestructible fuselage with rubber band mounted engine (Norvel .061 ) and the flying surfaces are sandwiched in between the top and bottom of the fuselage and held together with four 4-40 screws. The airplane has some weight to it, which is desired in the winds they fly in at Oshkosh and also helps with line tension. It's not the prettiest airplane you ever saw but the beauty of it is that you could make it look like anything you want if that is desired also. It does have an IC engine but the Norvel is as tough as an anvil, and would restart with a small electric starter in an instant. The glow plugs are the toughest I have ever seen also. This airplane will stand up to the Timex Lawn Dart Test!
  Larry Renger and the crew from The Knights of the Round Circle came up with a neat looking electric trainer that is also built with Core-Plast plastic called the ET-1. Our club is going to build up a few of these this winter/spring. It's an electric pusher design that gets the motor and prop away from the nose on those inevitable crashes, and has tricycle landing gear for pavement take offs. The interesting feature of this airplane is they control the motor speed by radio from outside the circle. This has the advantage of this is to control the flight speed of course, and also the flight duration and if need be, cut power on a crash. This airplane is also just intended as a primary flight trainer and Larry and the Knights have had lots of success with it. I think you can probably find plans posted in a thread also. If not I have those also
     So in short, like any job you have to do, you usually make sure you have the right tool for the job! If it's primary flight training, choose accordingly. If the pilot can competently fly the airplane is comfortable in moving on to a more maneuverable model, then the Skyraider or something like it is the obvious choice. Each pilot is different and it can vary how soon they are ready t move along.  Above all, have some fun with it!

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Offline Brian Courtice

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Re: foamboard electric trainer by Bob Hunt?
« Reply #12 on: January 15, 2022, 05:53:47 PM »
Thanks for the input. I appreciate it.
I did get a chance to try flying a basic electric control line trainer at the Joe Nall r/c event not too long ago.
I was immediately comfortable with basic circles, climbs and dives, and a simple wingover. I was tempted to try a loop, but it wasn't my airplane. I don't think I'll need to start with a primary trainer. I also might be wrong about that.  :)

My idea is to build something stunt capable that requires as little time or money invested as possible, and just go for it.
When I fly R/C I can fly inverted harrier circles, low to the ground rolling circles, inverted low passes, low level knife edges, etc.
I'm not fooling myself into thinking there won't be a steep learning curve transferring to control line, and I plan to crash/repair/repeat as needed.

Offline Dan McEntee

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Re: foamboard electric trainer by Bob Hunt?
« Reply #13 on: January 15, 2022, 06:36:36 PM »
Thanks for the input. I appreciate it.
I did get a chance to try flying a basic electric control line trainer at the Joe Nall r/c event not too long ago.
I was immediately comfortable with basic circles, climbs and dives, and a simple wingover. I was tempted to try a loop, but it wasn't my airplane. I don't think I'll need to start with a primary trainer. I also might be wrong about that.  :)

My idea is to build something stunt capable that requires as little time or money invested as possible, and just go for it.
When I fly R/C I can fly inverted harrier circles, low to the ground rolling circles, inverted low passes, low level knife edges, etc.
I'm not fooling myself into thinking there won't be a steep learning curve transferring to control line, and I plan to crash/repair/repeat as needed.

   Hi Brian;
    Like I mentioned, everyone is different when it comes to control line flying. It's my opinion that the only thing R/C can prepare you for is anticipating control responses. Control line flying is so much more close in and it seems like thing happen faster.Your brain is directly connected to the airplane by your hand and lines so things happen right now. When you are flying the R/C maneuvers, are any of those augmented by transmitter presets? There isn't any of that flying C/L stunt. When I explain what my attraction to C/L stunt is to people, I tell them it's as close to what it's like flying an airplane as you can come and still have your feet on the ground. So, you know more than anyone what you might be ready for, so, like you said, go for it!! And most of all HAVE FUN WITH IT!
   Type at you later,
   Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Online Ken Culbertson

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Re: foamboard electric trainer by Bob Hunt?
« Reply #14 on: January 15, 2022, 09:32:54 PM »
That looks great. I think I want to start with something a little smaller.
I've been an R/C flyer for almost 50 years, and I have tons of unused electric gear laying around.
Haven't flown control line in many years. I want something small and cheap to start out as I fully intend to destroy it learning loops eights and inverted flight as quickly as possible. :) I'm a pretty advanced 3D pilot, so we will see if my R/C skills will help me learn faster.
I am willing to bet that a lot of your skills will transfer, especially the most important one (to me anyway) of not having to think which way to move the controls upright or inverted.  You have been doing that on two plains simultaneously, now you will only have to do it on one. :)  The one you will miss the most is throttle.  You can't power yourself out of a jam. :(

Ken

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Online Bob Hunt

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Re: foamboard electric trainer by Bob Hunt?
« Reply #15 on: January 18, 2022, 06:32:06 AM »
I found the folder that contains the photos we took for the Park Cat article in Park Pilot magazine.

That was a really fun project, and I still have that plane in ready-to-fly-at-any-moment condition. Many of my flier friends who visit have flown that model in our backyard, and they all marvel at its outstanding performance.

Later - Bob Hunt






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Re: foamboard electric trainer by Bob Hunt?
« Reply #16 on: January 18, 2022, 09:09:32 AM »
That looks like a really fun little plane!
Laser-cut, "Ted Fancher Precision-Pro" Hard Point Handle Kits are available again.  PM for info.
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Offline Brian Courtice

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Re: foamboard electric trainer by Bob Hunt?
« Reply #17 on: January 18, 2022, 09:38:02 AM »
Thanks Bob!

Online Bob Hunt

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Re: foamboard electric trainer by Bob Hunt?
« Reply #18 on: January 18, 2022, 09:44:46 AM »
I found a copy of the text that was in that article. Unfortunately BP Hobbies, which is mentioned a a primary source for many of the powertrain and construction components is no longer in business.

Later - Bob


Park Cat

My good friend, Dick Sarpolus and I have joined forces to design a very simple to construct, all-sheet foam model that we call the “Park Cat.” Full size plans for the Park Cat are available through the Park Pilot Plans Service.

The basic material used here is 5mm thick White Construction “C” Foam that we purchased from BP Hobbies. You can also use the new Midwest Products Cellfoam 88. For the wing and tail components you can simply measure out the dimension of the wing and tail pieces onto the foam and carefully slice them out using a straightedge and a hobby knife, fitted with a #11 blade.

To layout the fuselage, position the plan over a piece of the foam and where there is a curved line use a straight pin to punch holes through the plan and into the foam at approximately ¼ to 3/8 inch intervals. For straight line areas on the fuselage, make pin punches through the plan at the beginning and end of each straight line. Remove the plan from the foam and use a pencil to connect the punches. Then cut out the fuselage with the #11 blade, using use the straightedge where necessary.

There are a few simple-to-make plywood parts needed for this model. These include the fuselage nose doublers, an elevator reinforcement piece, a bellcrank mount, an elevator control horn, a leadout guide, a pushrod guide, a battery area stiffener plate and a motor mount plate. The plan indicates what thickness plywood to use for each part.

You will also need two 36 inch long pieces of ¼-inch square basswood. One of these pieces will become the wing spar and one a fuselage spar onto which the two fuselage halves (top and bottom) will be glued. Note that these pieces are just slightly thicker than the 5mm foam pieces that they will be glued to. You can use a sanding block fitted with #220 grit sandpaper to thin down the bass wood strips in the appropriate areas to match the thickness of the foam, or if you have access to a small modeler’s table saw you can cut 5mm by ¼ inch pieces of basswood to begin with.

Once all of the wood and foam parts are cut out and sanded, and all of the hardware items are in hand (see the plan for a list of these…), assembly can begin.

Assembly

All the parts for this model can be assembled using 15-minute epoxy glue (Or even with 5-minute epoxy if you are fast!). Let’s start with the wing. Cut the wing spar to length and lay it down onto a piece of waxed paper on a flat building board. Apply a thin coat of epoxy glue to the edges of the forward and aft sections of the left wing that will butt up against the basswood spar. Make sure that the ends of the foam pieces are flush with the end of the spar. Press the foam pieces firmly against the spar and then weight the assembly until the epoxy cures. Repeat this process to glue the other two wing pieces to the spar, being careful to also glue the center joint of the wing halves.

Next glue the upper and lower foam fuselage pieces to the basswood fuselage spar in the same manner as you did the wing. Before you can glue the 1/32 plywood doublers in place - or any of the plywood pieces to the foam - you will have to make small punctures through the smooth skin that is on the BP Hobbies foam surface to allow the glue to grip properly. To do this accurately, position one of the doublers on its corresponding fuselage side and draw around the rear edges with a #2 pencil. Trace also the lightening hole locations. Using an awl or a scriber, punch a number of shallow holes, being careful not to punch holes in areas where the doublers will not cover them when glued in place. Using an acid brush, coat the inner face of one of the doublers with a film of epoxy and position it on the fuselage side. Weight this assembly and let it cure and then repeat the process to glue the other doubler onto the opposite fuselage side.

 Make a row of small punctures through the wing skins along each side of the center line joint, then slide the wing through the slot in the fuselage.  Line it up carefully and epoxy in place.
 
Glue the plywood elevator joiner piece in place (don’t forget the punctures…), and then bevel the lower forward edge of the elevator assembly at a 45 degree angle. Join the stabilizer to the elevator assembly using clear plastic packaging tape as a hinge (See the hinge detail on the plan). Cut a shallow slot and glue the elevator horn in place. 
Slide the tail assembly into the slot at the rear of the fuselage, line it up carefully in all axes and then glue it in place. Check the alignment often until the glue cures. Now epoxy the rudder in place with approximately 1/16 to 3/32-inch offset to the right.

Attach the leadouts to the bellcrank, but do not bend the line attachment loops yet. Glue the 1/8 plywood bellcrank mount in position. Bend the pushrod from 1/16 music wire and insert the right angle bend at the rear into the elevator horn. Use a small nylon keeper to secure the pushrod to the horn. Slide the 1/32 plywood pushrod guide onto the pushrod and leave it loose for now. Insert the right angle bend on the front of the pushrod into the bellcrank from below. Now hold the bellcrank over the mount in the neutral position and move the assembly fore and aft until the elevator is also at neutral. Mark the hole position and drill a starter hole for the sheet metal screw that will anchor the bellcrank. Screw the bellcrank to the mount and then position the pushrod guide about half way between the trailing edge of the wing and the leading edge of the tail. Make a small slot for the guide and epoxy it in place. Next glue the leadout guide in place and then bend the line attachment loops.

Position the motor mount that came with your motor on the 1/8 plywood motor mount plate and drill small starter holes for the #2 Sheet Metal screws. Glue the 1/8 plywood mount to the front of the fuselage and make sure that there is at least a degree of offset in it before letting it cure.

Glue a 1/4 ounce flat washer to the underside of the outside wing for tip weight and the assembly is complete.
 
Although you could bend up a 1/16-inch diameter wire landing gear with small, light wheels for flying from smooth surfaces, we generally fly this type model over grass fields where a landing gear isn't practical, or needed.  Get a friend to give you an easy hand launch and make a smooth dead stick landing on the grass.  The plane will even perform better without the drag and weight of a landing gear.  And a soft grass field is easier on the airplane when a crash does happen. 

You can dress up your model to suit you taste by adding some trim colors using water based acrylic paints. We’re going to hold off on painting ours so we can explain that process in a dedicated How-To later on.

I’m handing the keyboard over to Dick Sarpolus now for some power thoughts.
 
Power system stuff

The power system consists of a motor, battery pack, speed controller, and timer.  Taking advantage of today’s new technologies for high power and light weight, we use a brushless outrunner motor, Lithium Polymer batteries, an R/C type electronic speed control (ESC), and a timer specially made for C/L flying.  We want a system having about 150 watts of power for good flying, meaning we want a motor which will turn about an 8x4 prop and draw about 15 amps from a 3-cell 11.1 volt battery pack, that makes the 150 watts we want, and we’ll need a battery pack with a rating of about 1800 or 1900 mAh to deliver the current for flights of about 5 or 6 minutes duration.
 
For specific hardware recommendations, we used a BP Hobbies A2212-10 brushless outrunner motor, a BP Hobbies 18 amp ESC, a 3-cell 1800 mAh PolyQuest Li-Poly battery pack, an 8x4 GWS prop, and a Z-Tron timer (Available from BSD Micro R/C).  We also installed a prop saver device on the motor, it retains the prop with a small O-ring so the prop can move somewhat if it hits the ground, and won’t break on the landings.  And of course you’ll need a Li-Poly battery charger to handle the battery pack.  All of these components or their equivalents from other manufacturers are available from your local hobby shop or the many web-based hobby suppliers.

These electric power system components require proper care and handling, particularly the battery charging, to insure reliable performance and safe operation.  We urge you to follow the directions which come with the equipment and ask more knowledgeable hobbyists if you have further questions. – Dick Sarpolus

Flying

Check to insure that the center of gravity is where it’s supposed to be according to the plan. To adjust this CG position move the battery fore or aft in small increments, double checking as you go. Fly the Park Cat on 35 foot long .008 diameter multi-strand cables, and use a 1/2A type control handle.

Launch the model downwind to keep tension on the lines until some speed is achieved. This model is capable of most of the aerobatics that are in the official AMA pattern, so start with the easy ones like loops and progress as you gain confidence.
 
If you have any question about this project, please feel free to email  Bob Hunt at: robinhunt@rcn.com, or Dick Sarpolus at: rsarpolus2@comcast.net. Enjoy your Park Cat! 

Sources:

BP Hobbies, L.L.C.
140 Ethel Road West – Suite J
Piscataway, NJ 08854
Phone: 732-287-3933
Email: support@bphobbies.com

Midwest Products Co., Inc.
PO Box 564
Hobart, IN 46342
Phone: 1-800-348-3497
Email: customerservice@midwestproducts.com

GWS
138 South Brent Circle City of Industry, CA 91789-3050
Phone: 909-594-4979 
Email: usa@gws.com.tw

 BSD Micro R/C, L.L.C.
9054 Gum Rd.
Carthage, MO 64836
Phone: 417-358-9521
Email: bob@bsdmicrorc.com




   






 



   


 

Offline Brent Williams

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Re: foamboard electric trainer by Bob Hunt?
« Reply #19 on: Yesterday at 08:48:51 AM »
I have the full scans of the Park Cat article if anyone wants it.  It's too large to post here.  Send me your email in a private message.
« Last Edit: Yesterday at 10:02:13 AM by Brent Williams »
Laser-cut, "Ted Fancher Precision-Pro" Hard Point Handle Kits are available again.  PM for info.
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Offline Brian Courtice

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Re: foamboard electric trainer by Bob Hunt?
« Reply #20 on: Yesterday at 09:38:14 AM »
Yes please!
courtice61@gmail dot com


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