Bernard Cawley <  > wrote:

Bob Stought had an interesting idea to select propellers for electric systems by choosing a desired flight duration, calculating the current that would give that duration from the battery pack on hand (both great ideas) then choosing an appropriate prop by putting a fuse in the system which is near the calculated current -- and playing with props till the fuse blows.

Only one problem with this: a fresh fuse typically blows at something near 1.5 times its rated value -- so the 15A fuse he suggested isn't likely to blow until somewhere around 22A unless it's been used in these tests for some time. Also, they're not all that consistent from one to another.

Really the best way to do this is to follow Bob's method up to the determination of the current, but then actually MEASURE the current in the system being evaluated, with either a shunt and a digital voltmeter, or better, that marvelous tool Astro Flight sells called a WhattMeter.

These now come in two flavors. There's the original, for currents from 0.1A to 100A (and up to 60V). Now that's been augmented by a new "Micro Meter" for currents from 0.01A to 15A (and 15.9V).

Those values are more suited to indoor/park/schoolyard flyers -- perfect SMALL subjects. I've just added the Micro version to my toolchest along with the other, and am finding all sorts of uses for it. For example, how much current does that servo really draw, and how much current can that BEC regulator provide before it gets hot?

Sure, these instruments are $60 each, but boy are they worth it.

Bernard Cawley, Auburn, Washington USA

Tom Pearson <  > contributed:

Gee, Roy Clough mentioning the balloon tank. I was beginning to think that I was the only one left in the world using one. This idea of a slack filled balloon goes way back to the days of the Jim Walker Firebaby U-Control plane, powered by an Anderson Baby Spitfire .045.

Jim had a balloon tank that you installed inside the canopy of the Firebaby. For those who don't remember, the Firebaby was a profile fuselage with a molded airfoil wing much like some of Jim's gliders.

It came pre-painted, with a fancy red and blue trim. Probably the first ARTF. I got one under the Xmas tree about 1949 or so.

I still use the balloon tank in lightweight R/C aerobatic 1/2A planes, to save about one ounce weight of the blow-molded 2-ounce Sullivan tank. Lightness flies better.

Our local card shop sells the balloons, which will hold about 2 ounces of glow fuel. The balloons need to be washed out before use, as they have a talc-like powder in them when new.

Tom Pearson

George Edwards <  > asks:

I am looking for an instruction sheet for a FOX 19R/C engine, model 219000. Fox no longer has this sheet available. If someone out there has one, would you make a photo copy and send to me? Will pay cost of copy and postage. Thank you.

George R Edwards, 210 East Lincoln Ave., Altoona, PA. 16601

David Felin <  > submitted:

After reading Scott Winans' submission in Posting #373, I wanted to share the results of some experiments I've done with the TD .09. Somewhere, maybe through the SMALLnet, I heard that the AP Wasp .061 R/C carb could be made to fit the TD .09. Turns out it's a perfect fit on the stock TD carb spigot (minus the venturi and needle valve assembly).

I may have had to drill the spigot I.D. out slightly oversize, I can't remember. I then epoxied the carb in place and had a runner. I suppose you could drill through both the spigot and lower carb body, then thru-bolt the whole mess with an O-ring thrown on for good measure -- but epoxy is quick, easy, and works well, so that's what I did.

What a great little engine! I don't own a tach but the idle seemed plenty low and rock steady. I suppose you could improve the carb by drilling an idle air pilot hole, but I was happy with the way it idled stock so I left it alone. I imagine the AP carb venturi is probably smaller than the diameter of the TD venturi (don't know, too lazy to measure) but the top end with a 7x3, two head gaskets, and with a TD head machined to accept a conventional glow plug, was still "hair-raising" on 10% nitro fuel. Excellent fuel suction too.

With an 8 x 4 it should make a great little sport engine. Mine pulled an HOB Cub (55 inch span clipped down to 45 inches, approximately 30 ounces all up) handily. Throttled back it ran seemingly forever on a two-ounce tank. If memory serves, I paid around $12 - $15 for the carb. I've got a Norvel .074 also, and the TD R\C will blow the doors off it at approximately the same weight.

Dave Felin

Mark Vance <  > reports:

With regard to the recent discussion about refitting Norvel .061s with C*x heads, I have to say that my experiences have been dismal doing so, with both regular and high compression C*x heads.

I have always achieved much better performance with the newest style Norvel Plugs (the kind that have the ring for the standard Ni-starter), and both idle and top end performance suffer when using a C*x plug. I feel that if you want to sacrifice top end for idle, the best way to do that is to add shims to the head.

Also, 35% nitro has always yielded better performance at both ends of the scale for me, and I always use 20% oil 80/20 synthetic/ castor blend. I have 50 some odd hours on a couple of my dozen-or-so Norvels, and this combination has yet to disappoint me. Heck, I can't seem to wear them out. As to large props on the Norvels, I feel that anything over a 6x3 Master Airscrew is just too much prop for this engine to spin.

If some of our SMALLsters require a slower plane, for taxing and cruising, I'd suggest lowering the prop pitch instead of looking for a 4000 rpm idle. These little fellers will sometimes turn near 20K for us, and asking a tiny, low inertia engine to have a 5-1 top-to-idle ratio is just being too demanding on a $50 engine.

As an aside, the Norvel .074 and the TT .07 will happily spin 7x3s and they have great idles as well, due in part to more inertia, and unaggressive venturi sizes. I've also found that the Norvel .074 seems to have its best balance of speed and thrust with the way overpriced APC 6.3x4 props they sell as ".10 Combat props".

I have 2 .074s with 6.3x4's on a Gus Morfis ME-262 I scratch- built, and even at 2.75 pounds it still has enough thrust, and enough speed to fly very realistically; and the .074s sound much softer than anyone's 10-15 sized engines would have.

Happy Flying, Folks! Mark Vance.

Roy Clough <  > wrote:

I certainly agree with Scott Winans about the .09 Cox Medallion. I've had great luck with both it and the TD. I used one for my Aileron Trainer (Model Aviation, Dec.'96); in fact. it is still in that rebuilt plane. It throttles very well indeed, starts very easily, and has plenty of power.

However, when throttled back a couple of hundred feet in the air, it is so quiet it is sometimes difficult to decide if it is still running. My only beef with the engine is that the pressed-together throttle sleeve top kept coming apart. I finally fixed it with a couple of 2-56 screws at 180 degrees.

Because of the fact the engine can be instantly throttled down or up without stalling out it makes a good choice for two-channel throttle control using a quick blip of up or down to open or close the throttle.

Roy C.

Carl Dowdy <  > asserts:

It amazes me that so often a significant number of modelers can be longing for a product and no manufacturer notices. Except, it seems, for Norvel. There has been a lot of discussion in SMALLnet about 1/2A starters and clunk tanks.

Norvel has both. I have seen one of the Handi-Starts in a hobby shop, and it is very nice quality. It is manufactured by Lite Machines (makers of the LMH-110 1/2A helicopter) and available through Norvel. In addition, Model Airplane News recently had a photo of Norvel's new 1/2A clunk tank. I believe it is roughly $10, and has a clunk and vent for filling. It also increases fuel capacity by protruding through the firewall much like the JK Aerotech "Slickmount" engine mounts/tanks. Thanks, Norvel, for listening.

On another topic: for Christmas I received one of the small electric free-flight models available through Harbor Freight. This model was mentioned on SMALLnet quite a while back. It is attractive, flies well, comes with everything needed except a couple of AA batteries, and costs an unbelievable $9.99. The part number is 42619-2VGA, and you can order it at < http://www.harborfreight.com >.

They also have another model that I have not (yet) tried. It is 43678-0VGA and is $12.99. Small models do not need to have radios to be fun! Thanks again to the SMALLnet gang for making this e-mail forum available. Carl Dowdy

Curt Hulett <  > has a problem:

I just bought an Aspire EP electrified glider (79" span, 680 square inch wing area), and find the weight will be near 4 pounds. That's 10 ounces per square foot wing loading!

Sounds like 6/7 cells will be pretty anemic power. This is my first venture into electric; maybe I made an expensive mistake. As heavy as this thing is with batteries & all, I should have stuck with small glow. Even a .15 would have been whole lot lighter.

What do you think about me throwing away electric stuff, mounting a .15 glow engine on the nose of this thing? Any guidance would be appreciated. I hate to try flying something that can't do anything but crash. Curt

John Rossetti <  > wonders:

I noted that Nicads, even though they reach "normal peak voltage" after charging, may be dying.

I have had two sets of 1700 mAh Sanyos for almost two years. They continually charge to the same peak as when they were new. So far I have not noticed any change in flight times. It was always my impression that Nicads would show a dramatic decrease in peak voltage, that is, a much lower one, if they were going down the tubes, so to speak. I record the peak charge voltage each time I charge them and have used that as my guide for reliability. Am I wrong ?

Thanks for your comments, John Rossetti

Dal Hamlin <  > reports:

I have been flying an Aquastar off powder snow for two winters now (haven't had a chance to try it on water yet), and the takeoff run is around 30 feet. Takes about twice as long on grass.

Landing run after touchdown is about 50 feet, depending on idle rpm. All this at 8000 feet MSL.

I am using a BigMig .061 (earliest version) with a Cox TD high- compression head, with a Cox black 5 1/2x4 propeller and Norvel 25% fuel. The plane flies very nicely with the tip floats on with this set-up at 20 ounce flying weight.

When you build it, I would suggest running the pushrods out of the fuselage top rather than under the stabilizer; also extend the chine strips farther forward, up to the rear of the nose block. I used 1/4" triangular stock for this (a la Ace Sea Dancer). It's a bit easier to form than the called-for plywood strips, and works just as well.

Hope this gives you some clues.

Dal Hamlin, Gunnison, Colorado

Dereck Woodward <  > amplifies:

Water plane flying - you gotta try it!

Stuart McKenzie asked about the Aquastar's performance.

The only Aquastar I have seen in action was an electric one - more of a Scubastar! There's a lot of concern that it hasn't enough front end volume to the hull to avoid the high thrustline pulling the nose down into the water. The one I saw, resorted to a hand launch over water -- the subsequent landing was not a pleasant sight either.

My pet favourite for waterplaning is the Hobby Hangar "Pondside" -- it was previously the Ace Puddlemaster. Same shape, different structure, same Scott Hartman design basically. The Ace kit was 'die-crushed' and ended up $65-ish in Hobby Shops, or down in the 40's when Tower firesaled their last few off.

The Pondside is beautifully laser cut, and costs around 46 clams with shipping, direct from HH at < http://www.hobbyhangar.com >. I reviewed the PS at < http://www.ezonemag.com > -- look through their reviews section, it was only mid last year. There's a bunch of them on the unofficial Pondside and Puddlemaster Owners Club, around < http://www.weekendpilot.homestead.com >.

I've seen a Puddlemaster fly great on an Enya 11 that cost its owner around $5.00 at a bring and buy! Your 07 could well power a Pondside built light, at 48" span.

My electric ones, especially the seven cell / Astro 035 Pondside I fly now, would hack that pond of yours as long as the wind was pretty up and down it -- crosswind on water gets excessively exciting for my tastes! As that one only weighs 40 ounces fully fueled (14-ounce nicad pack), a glow conversion would be some lighter. Turns I can do in around 10 -15 feet, while landing is a shorter process than take-off. Full stall land onto water -- the roll-out is about six inches and you really make a splash!

There's a "large scale" Puddlemaster on my pages. Ace's kit had the fuselage drawn at 75% -- add an Ace foam wing and there's the baby PM (Tubmaster???). It's a bit erratic, but a slightly longer wing would help. Folk have even added a bay each end to the standard kit's wing to cool it down some. It is sure not a three-channel trainer model, and will do a good spread of three channel aeros.

Ken Willard did a lot of baby floatyboats that would benefit from your fleet of little donks; might be worth looking one of them up.

Regards, Dereck

Pat Beard <  > has a question:

Ken Elder <  > wrote:

I'm flying a Project 15 built by Jim Kiehl (of ME-163 plans fame). This is the turbojet-powered version of the WWII Messerschmitt Me-163, a flying wing. It's a prop-jet model, not a ducted fan.

Originally flown with a Cox .09, when I got it I just had to try the Thunder Tiger .07. What a great powerplant.

Since the P-15 is a flying wing, it's sensitive to balance; so I'm flying it without muffler (OK at our field) and it is a screamer. Running it on Norvel 25% with a 6 x 3 it really turns up, yet throttles great. No, I didn't tach it, but it sounds like it turns the same prop about 2000 rpm higher than the Norvel. Reminds me of a TD .020.

I'm ready to sell my Norvels and my MP-Jet diesel!!

Ken Elder

Tony Turley <  > contributed:

Jody White asked about converting a Cox "Recon" model to R/C.

I recently completed my R/C conversion of the Recon. I hope to be able to fly it in the next couple of weeks if the weather cooperates.

I electrified mine with an ancient (early 90s) AP29R drive set from Kyosho. I've had a lot of success using the AP29R drive sets in 1/2A planes, so I expect this model to fly well. Unfortunately, these drive sets have been unavailable for years. I also used a Castle 25 ESC, and I'll start out with 7 N650s. I plan to eventually try 7 800 NiMHs.

I had to bore a couple of holes through the back of the fuselage for the pushrods, and I scrounged the elevators from a long-defunct foamie. Two Hitech mini-servos round out the radio.

I'll let you folks know how it goes - soon, I hope.

Tony Turley, Scott Depot, West Virginia

Ron Boucke' <  > reports in detail:

In posting #373, Jody White inquired about converting the C*x Recon from a FF model to R/C. I also have converted my Recon to a single-channel R/C, rudder only. My reasoning for not adding elevator control was weight gain and the fact that the motor run has a short duration.

The servo is externally mounted. I hollowed out a space for the FMA S-90 servo on the left fuselage side just aft of the rear wing dowel, and right above and parallel with the black/red mylar decal which runs along the fuselage. Then I drilled a hole from that cavity across the fuselage and met it with another hole drilled from the rear of the cabin on the right.

That provided a stuffing compartment for the servo wire & connector, which I attached to a short servo extension cable. The extension was placed in a groove I routed along the inside of the right cabin wall to keep it out of the way of the camera box, which has to slide down in the cabin.

The servo extension was now in the forward cabin where it will plug into a Tetra receiver. I removed the pre-set rudder screw which came with the Recon, added a control horn to the existing rudder, and epoxied a short piece of clear plastic tubing on the fuselage to capture the wire link from servo to horn.

All of this explanation is a lot of words, but rather easy to do without spending a lot of time in the process. Finishing up, I removed the battery box (which was pre-wired on the camera radio unit) and terminated the wire with a Futaba connector so it can plug into the Tetra receiver for battery power.

In the battery box compartment, I placed a 250 mAh square pack to power both Radios: the Tetra and the Cox Photo gear (27 MHz). If you're just flying and not taking pictures, you can shut off the camera radio with its own switch.

Last item was to mount the radio on/off switch and charge connector. That mounted just rear of the front wing dowel left side, and above the Cox photo radio box. The only inconvenience to that location is you must remove the switch in order to remove the camera radio gear; it does not interfere with the removal of the camera itself.

All-up weight came out to 26.8 ounces; no lightweight for sure. The CG remained at 2 1/8" behind the leading edge. Wing area is 308 square inches, and wing loading I believe came out to 12.5 ounces/square foot.

I broke in the Surestart engine with several bench runs. With a 6X3 prop and Norvel 15% fuel, it tached at 14,500. The motor runs are short, about a minute and a half; just enough to get some altitude and glide back while taking a picture. Remember, your are dealing with two transmitters now, so it's nice if you bring someone along to handle the picture transmitter or vice versa.

Does all this work?...Dunno, I still got to get it out there and fly the darn thing!!!

Ron Boucke' Sterling Heights, Michigan

Mark Garvey <  > adds:

Here's a quick note about a "recon plane". I built a Telemaster 40 some years ago and used a camera mount from Hobby Lobby, cheap AND effective. I could only shoot once per flight, then had to land and advance the film. But with minor modification you could use an electric advance camera for more shots.

Modern, lightweight cameras could EASILY be used with some of our small models. A Lazy Bee with a .15-.21 and the 48 inch wing would be a fine camera platform; even better with a good electric so you'd have no vibration with the shots. Some of the older Disc Cameras were auto advance and were tiny as well as cheap.

You can get really cheap 110 film cassette cameras for nearly nothing, not auto advance, but workable. Even digital cameras would work if you really wanted to risk them. Some guy in our local club is reported to have used a very nice auto advance camera some years ago in the nose of a large model. He experienced a "glitch" and got ever-increasing size shots of a train, before his plane impacted.

Mark

Colin Rhodes <  > announces:

My latest project is a gorgeous little Lady Bee from Clancy Aviation and it's coming on really really well. It's being built from plans and that's a new thing for me. I have kit bashed but never done my own cutting and wood selection before.

I was thinking about putting my GWS Pico servos plus a Feather receiver into this 22" span beasty. It has a classic Lazy Bee type wing (scaled down) and control surfaces that are a tad larger than my Lite Stick.

It won't be a real slow flyer, but Bees tend to be on the not-so-quick side by nature, so I expect docile flight.

Will I be putting my GWS servos in peril here? I'm going to build two models - one .049 and another with a Speed 400, or perhaps even the GWS motor (would that work - I think it may come out too heavy?)

I want to compare gas and electric and write up my findings!

How do I work out how much torque I need in a servo anyways? Is there some rule of thumb? Thanks, Colin

Tom Arcoleo <  > announces:

Don't know if this has been posted here yet, but the University of Florida is hosting the 2001 Micro Air Vehicle competition. Check out details and see what is purported to be the world's smallest R/C aircraft at < http://aeroweb.aero.ufl.edu/microav/Main.htm >.

If you are near Gainesville on April 7 & 8, that would be a contest to see. Tom Arcoleo