From the Lab - October 1998 - RC Groups

From the Lab - October 1998

Steve provides some thoughts on the 1998 KRC Electric Fly, shares further information on the Jerry sailplane, and presents his Tool of the Month.

Some Thoughts on KRC

This year I attended the KRC Electric Fly for the second time. This annual event, held in Allentown Pennsylvania, is covered extensively elsewhere in this month's E-Zone, so I will mostly limit my coverage to some personal comments.

Unlike last year, when I was just a 'lurker' with no planes to fly, this year I brought not one, not two, but NINE planes. By the end of the weekend I had flown 7 of them. If you wanted to fly, there were plenty of opportunities to do so. Yes, I spent some time in the E-Zone booth, too.

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This was in many ways a new experience for me. I am used to flying alone; for the weekend I was flying with a lot of people around and a lot of other planes in the air. I had expected this to be a real problem, but it wasn't really; most people kept their planes close to the runway, so I flew my planes - my Jerry, mostly - up high and over the trees. The only time I had to mix it up was launch and landing. I am also used to flying on an unstructured field - no runway and no designated landing area. At KRC there is a paved runway, with the wind usually about 90 degrees to the runway, and a rough grass landing area beyond it. I did not really like having the last part my landing out of sight - the grassy area slopes away from the runway, and is not really in view from the pilots stations. But I lived with it, and the only damage I did was a ding to the leading edge of my Graffiti - which I landed in plane view, right at the edge of the runway - and hit a metal stake used to hold a bungee for launching EDFs. Ouch!

I had expected to have to use my car battery to run my battery charger, only to discover that the Keystone RC club had set up multiple charging stations, equipped with 12V car batteries, chargers to keep the car batteries from going flat, and 120V AC power for AC powered chargers. This was great!

KRC also provided an interesting look at what it is like to fly in other places. There is definitely something different about the air in Pennsylvania. Immediately after arriving on Friday evening, I did one of the longest flights I have ever done with my Cumulus.  On Saturday I did my longest flight on my Jerry. And on the way home I saw many hawks and other large birds circling in thermals - far more than I have ever seen on a single day here in Massachusetts.

When I wasn't flying, I talked with other pilots, looked at their planes, and watched them fly. The pilots at KRC range from beginners to professionals, and the planes range from boring trainers to museum quality scale to high performance competition planes. With over 250 pilots registered, there were probably 1000 planes at the field, so there was plenty to look at. Just being in an environment where there was so much to see, talk about, and do, was really a lot of fun. What a fun bunch of people!

Steve Neu, who is a member of the US FAI F5B team, and came in 9th in the last World Championships, was at KRC flying one of his competition planes. This plane has a motor, radio, 27 nicad cells, and just enough fiberglass and kevlar to stabilize the equipment and make it act like an airplane. The flight characteristics are truly astounding - vertical launches and dives- and give me something to aspire to. If you have never seen a competition F5B plane fly, you have not seen really high performance electric flight!

Last year I spent far too much time looking at the vendor booths, with the inevitable result of purchasing several kits that I still have not built. This time I decided that I would spend Saturday flying, and look at the booths on Sunday morning. Unfortunately, some of the vendors headed home after closing up on Saturday, so I never got to talk with them. I guess the solution is to spend Saturday morning covering the vendor booths, and THEN go flying. There were a good variety of vendors present, and lots of things to look at. Hobby Lobby International, Northeast Sailplane Products, New Creations R/C, and Penn Valley Hobby Center all had large booths. Many smaller vendors, such as Unbeaten Path, Aveox, Model-Air Tech, FMA, EMS, Kress Jets, and Bill Griggs Models were also present. None of the model manufacturers that frequently help sponsor glow powered events were present - the Hobbico family, Horizon Hobbies and JR, Futaba, ZAP, Goldberg, Midwest, Sig, and the like were all absent. We don't get no respect!

There has been a lot of traffic on the EFLIGHT list with complaints about how the KRC Electric Fly was run. I think some of the complaints are valid, but some of them are just whining. Overall, I think that KRC is a well run, well attended event. What would I change if I were in a position to make changes to KRC?

  • Designate a separate flying area for slow flyers and park flyers, well away from the main runway. These planes spend their entire flights hovering over the same area where they take off and land, so it would be much safer for everyone if they were flown in a separate area. The roadway on the right edge of the field would be a good place, especially because it would give them a runway that is about parallel to the wind.
  • Move the pit area, vendor tents, and pilot stations back about 100 feet from the runway, so that the grass on that side of the runway can be used as a launch and landing area for the many planes that don't have landing gear. Botched launches were made much worse by hitting the runway instead of the grass.
  • Change the rules of the now very boring all-up-last-down (AULD) everyone-wait-two-hours-for-the-last-one-to-finish event. The upcoming San Diego Electric Fly includes a 'limbo' every half hour during the AULD event, which should even things out a lot. Someone who is good at catching thermals will have to catch a lot of them!
  • Publish a list of the distribution of frequencies, so that some of us can change to lightly used frequencies.
  • Give the manufacturers and vendors time during demonstration flying, rather than encouraging them to fly all day, which ties up a few frequencies.

If you are going to KRC, or a similar event, you might want to keep in mind the following:

  • Bring planes on several different frequencies, or be able to easily change the frequency on some of your planes. By next year, my Hitec Prism 7 will include a 'Spectra' frequency synthesis module, and I will bring a few extra receiver crystals. I was sharing channel 44 with too many active flyers - including the demonstration pilots from Hobby Lobby - so I just gave up flying the planes on 44 and limited myself to my planes setup for a different transmitter on channel 16.
  • Bring your own food and drink, it at all possible. Although there were several food vendors on the field, I would only consider eating packaged, cold food from them. Bring water! It is easy to get dehydrated during a long day in the sun.
  • Don't bring marginal or poor handling planes. The commotion of having a number of planes in the air at once will only make them worse. Some very marginal planes that were flown repeatedly (I remember a twin which barely flew - but did it a lot!) were a real hazard on the runway.
  • Don't worry about a 12V supply for field charging. 120VAC outlets for battery chargers were available in the pit area, which greatly simplified battery charging.

See you next year at KRC! If you are into electric flight - and you must be if you are reading this - KRC is an event not to be missed!


A Few New Planes at KRC

I did see a number of new planes at KRC. Park flyers and Electric Ducted Fans (EDF) are all the rage, and there were plenty of both.

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This photo shows Carolyn Defrancesco, (Mrs. Northeast Sailplanes) holding the Elfi ARF park flyer. This plane flew many times over the weekend. Check the Northeast Sailplanes web site [ ] for details.

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This photo shows one of the two Hobby Lobby Wingos that were in the air for much of the weekend, often in loose formation. Check the Hobby Lobby International web site [] for more information.

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Here is Bill Griggs of (you guessed it!) Bill Griggs Models, showing off his new BD-10 kit. The BD-10 is a homebuilt jet, which I find just amazing. The model uses a WeMoTec ducted fan unit. Check out Bill's web site at [].

There were plenty more new planes, but I didn't take pictures of them!



Some More Thoughts on the Hobby Lobby Jerry

I have received a few emails from e-flyers who have built the Hobby Lobby Jerry. If you read my review, you already know that I raved about the plane and drive train.

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From: Bob Douglas <silentflyer(at)>
Subject: Holy ****!!!

....what the subject line is about is ......The JERRY !!!!! Check out a Hobby Lobby catalog if you have one.

The Jerry is a electric sailplane by Gerasis from Czech Republic.

Power is a Mega 10 SP from the same country and it is juiced by a 10 cell (12 volts) 1250 maH pack. It puts out 1 HP (750 watts) and draws 90 amps !!! They call them flying arc welders for some reason <g>

Whoa !!! What a airplane. It climbs at about 80 !! degrees !!! (REALLY). Launches are hair raising because of the prop torque. You can only launch at about 2/3 throttle or the torque will put you into a unrecoverable left roll.

Once airspeed is built, you can increase to 100 % and start an almost vertical climb. And it climbs there in a HURRY. 20 - 30 seconds and you are at almost speck height !

Cut the power and Jerry DOES thermal with the best of them. And the L/D is remarkable. She covers ground and doesn't want to come down.

Landings are a joke right now. I have spoilerons programmed in but haven't had the courage to use them yet. Jerry hits a cushion at about 1 or 2 feet and (like The Energizer Bunny) just keeps going and going and going.........

If Jerry lives long enough to let me learn the intricacies of launching him (her ?) it's going to be "Holy ****........." all the time --

So, there you have it. It is NOT just my opinion!

I also received an email from Bob asking about the spoileron setup:

"I tried the spoilerons up at about 5 mistakes high <BG> and it was a good thing, I have too MUCH up elevator dialed in and kept stalling it.

Do you use up elevator in conjunction with the up ailerons ? Really, I don't know the answer on that since I've only used flap/elevator on normal, unpowered sailplanes before. "

I have found that my Jerry needs a bit of down elevator when the spoilerons are up - without it, the nose goes up, and it starts to mush along. I have not yet programmed this into my transmitter - I just hold in a little down during the last few seconds of landing when I have the spoilerons deployed. My review includes a diagram of the radio setup that shows how the controls which are normally used for flaps were assigned as spoiler functions.

I have done a lot more flying with my Jerry - I did 5 flights at KRC, including my longest one to date - and still really like it. The biggest problem I have with it is that the local schoolyard is not large enough for such a fast moving plane, and the athletic fields where I do like to fly it are frequently covered with children playing soccer. I am looking forward to winter, when the so-call athletes stay inside, and I can have the fields to myself!


Upcoming Projects

As usual, I have a number of projects under way. In the next few months I will have on the E-Zone a review of the Multiplex Twin Star. The Twin Star is an all moulded foam plane with two Permax 400 motors.

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After spending too long as a hangar queen, I finally got out my Skyvolt and have been flying it again. I had never been very happy with the original Astro Flight 05 drive train, because the plane lacked any real vertical performance. I wanted to replace the motor, but I did not want to have to replace the oddly shaped 7 cell battery packs with higher cell count packs. So I recently replaced the Astro with a Hobby Lobby/Mega Mini 7, which requires only 7 cells.  This has made the plane much livelier. I will present any analysis of these two drive trains.

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After too long a wait, I have a small collection of Multiplex Permax motors. The Permax 400 looks a lot like a typical 400 class motor. The Permax 400 BB looks a lot like the Graupner Speed 480 Race. And the Permax 450 Turbo looks a lot like the Kyosho AP29L which is used in the T-33 EDF. This motor produces about the same power as a Speed 500 in a much smaller package, and looks like a great way to improve the performance of some types of Speed 400 planes. The specifications of each of these motors are undoubtedly different from the ones they look similar to. I will present an analysis of these motors, and some suggestions on their use.

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I recently received the latest version of the Castle Creations Sprite motor control. This photo shows the 25 Amp Sprite XLR with the year old, 20 Amp Sprite. If they get any smaller, they will get lost! I will be presenting a technical review of this new control.

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Tool of the Month

Dremel [] makes a range of 'Moto Tool' electric powered hand tools that are great for a variety of model building tasks. I have had one of the typical variable speed models (395) for many years, and my only complaint has been that it is sometimes hard to hold, because I have rather small hands. But a few months back I wanted to use it to remove part of a bulkhead in my Cumulus, and I could not use it because it simply would not fit in the fuselage.

But I really wanted to remove the lite-ply former neatly, and a file or knife were just going to be far too much work. Then I remembered that Dremel sells a Flex-Shaft Attachment model 225 for Moto-Tools that sells for about US$30.

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The flex shaft is 36" / 91cm long and only 0.5" / 1.3cm diameter, so it can be held like a pen. It can also be held inside a model fuselage, which is what I wanted to do. I have found the smaller diameter much easier to hold for intricate work. The flex-shaft attachment is installed on a Moto-Tool by removing the screw-on plastic piece just below the collet, and replacing it with the tool end of the extension. It only takes a minute or so, and is completely reversible. The flex-shaft uses the same collets as the Moto-Tool.

If you would like to recommend a 'Tool of the Month', please feel free to contact me at skranish(at)


Source of the Month

This month I am going to suggest looking at E-Zone sponsor Unbeaten Path Imports, and one of their suppliers, Hoellein.

At KRC I purchased a Hoellein 'Wonder XXS', a CNC cut kit of a Speed 400 size version of the Sig Wonder. At US$55, this is not a cheap kit, but the cutting of both balsa and ply is absolutely beautiful, and it should fall together in about two evenings. The kit includes CNC cut control horns and bell cranks for the ailerons.

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Hoellein, based in Germany, has a web site at They sell CNC kits for electric flight.

If you would like to recommend a 'Source of the Month', please feel free to contact me at skranish(at)



This document is copyrighted (c) 1998 by Steven Kranish, and may not be copied or used in other forms of publication (electronic or paper) without written permission from the author. I will probably grant permission, but I would like to know about it, so go ahead and ask.



If you have any questions, please feel free to contact me at skranish(at)

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