SMALLnet post311

From our experience, fuels with higher nitromethane content seem to dissolve the rubber more quickly. I don't know much about science, but I know nitro is a very active chemical that attacks almost everything.

Also, modelers who leave their fuel in the bulb or syringe during a day of flying will experience more problems. Defueling from the bulb into the fuel bottle seems to contribute to a gradual increase in the amount of bad stuff as the fuel bottle gets lower. Old bulbs are much worse than new ones, too.

I'm sure that there are people out there who successfully use rubber bulbs, or syringes with rubber plunger seals in NORVEL .049-.061 engines. Still, over the last five years, I have spoken with hundreds of NORVEL customers who had problems with glow plug contamination, that were cured after changing over to a non-rubber fueling method.

If anybody out there is having good luck with a rubber fueling device, keep using it. But, if I remember correctly, it's the exception that proves the rule.

It might be interesting for readers to know that the first two years of NORVEL's existence were filled with many frustrating calls from customers whose problems we could not solve. Our experiences with the motors had been great, but some guys were having trouble.

Finally, Paul Arlton of Lite Machines was at a helicopter fun fly in Columbus. Five guys showed up with their NORVEL-power LMH-100 helis, asking Paul to get them running right. As a first step, he started by using a clean plug and his field kit, which has worked fine on all his helis. All five helis started and ran great.

The five guys were all really happy. Then Paul noticed that each one was using a rubber fuel bulb for fueling. He is a first-rate engineer and figured out the problem after taking some temperature measurements on the NORVEL and other engines. It turns out that the NORVEL engines run 50 degrees F cooler than a TeeDee 051. So they don't get hot enough to burn up the dissolved rubber.

There would have to be many cases of modelers successfully using other engines (that run hotter than NORVELs) and rubber bulbs/tubing/etc.

I would also like to tell Ed Stevens that I will buy 6 Norvel .020's with throttle control, and a few .010's. In our dreams?

I think you could sell a few on this side of the Atlantic too. Maybe you could link up with LMH 100/110+ crew for some .020- powered micro helicopters. Yep, I'll need one of those, too.

I run two Norvel .061's: one in a Light Machine 100 -- and the combination is excellent, with the Norvel always behaving very well. The other is in a Fred Reese/Ace Simple CAP 21 -- another excellent combination. Thanks, Norvel and Co.!

We are eagerly awaiting the arrival of a Norvel/LMH 100 .020 Micro Chopper that is smaller than the Piccolo and flys for 4 times as long -- and if that wasn't enough, a 4 channel Micro CAP 21.

That enables this carb to be adapted to a variety of engines. My next project will be to install this carb in a VA.049. The carb needs a little simple rework, but the good part is that it only costs $14.50. Also, you need to purchase an Ace Throttle Sleeve from Sky Hobby. These cost about $5.00.

I have seen in SMALLnet postings that a lot of you guys are seeking this sort of information on how to throttle a Cox engine, parts, etc. I have created a web site telling and showing all. Go to < http://community.webtv.net/dongarry/TD049 >. Hopefully this site will help you throttle that Cox engine of yours.

Having heard all the pros and cons on the Norvel engines, I would like to say the engines have been good to me. The new Revlite model Big Mig .061 runs super cool. You can put your finger on the case while the engine is running wide open and the case feels cool to the touch! Mine has good high power end, and good idle and throttle response.

I would like to say a few things about the Wasp .061 from Hobby Lobby. At first I was very disappointed because the engine had no ball bearings as advertised. After giving the engine a chance and bench-running it, I have decided it is indeed a fine quality engine.

It is a near clone of the Norvel, but with a few differences; some of which I like; such as true ABC piston/cylinder set-up, split collet prop drive (why did Norvel get away from this?), piston pin is retained with a "G" clip (not staked in). Also, I like the round intake (easy to adapt various venturis, carb, etc.) The power is nearly equal to the Norvels, using the same plug, fuel, prop.

The new Revlite might have a slight advantage in power over the old type Big Mig and the Wasp. Also most of the Norvel parts and options will bolt right on this engine, such as glow plugs, starter spring, prop spinner, etc. Don't be afraid to buy one. I've had fun playing with mine!

Re Jim Branaum's problems in getting his AT-6 to come out of a spin, there are at least three possible reasons I can think of for this.

One, the model may be a little tail heavy. I flew the full scale aircraft while in the Air Force in WW II, and when flying them solo we always flew in the front seat to keep the C G in the right area. The T6 (Harvard we called it in the British Air Forces), can be a b---h to get out of a spin if the C G is too far aft.

Two, Jim may not be using the correct spin recovery technique, which is: 1, apply full opposite rudder until the rotation stops; 2, then down elevator until the airspeed increases to full flying speed (most aircraft lose airspeed in a spin); 3, ease out of the resulting dive to level flight and increase throttle to normal setting.

Three, the vertical stabilizer and rudder on the T6 are not any too large, and a small increase of about 10% can do nothing but help to increase stability and spin recovery. This of course applies to a great many if not most scale models.

As far as flying techniques are concerned, what works for the full scale aircraft usually works for the model too, and the above is how we were taught to recover from spins. I hope this will help.

As I recall, spins in the AT-6 were not very comfortable. To get one out you stood on the rudder and then popped the stick forward rapidly and forcefully. Might work on the model. Ol'Bob

A little story: NavCad Class 20-55 was the last class to fly the SNJ (Navy version of the AT-6) in basic. My "new" instructor on this one day was a hot young Marine Lieutenant just back from Korea. Our mission for the day was unusual attitude recovery.

On arriving in the practice area, I was told to close my eyes and look down into the cockpit until he said otherwise, whereupon I would take the stick and get us back to level flight. After a few mild things such as inverted recovery, hammerhead stalls, etc., he said, "Hang on now..."

I did and there ensued some mighty grunts and curses from the back seat that frankly put me in fear for my life. Eyes shut, I felt the plane go through all sorts of wild gyrations and throttle changes and then I heard the dreaded words, "GET READY TO JUMP, IT'S GONE INTO A FLAT SPIN!"

My eyes opened, my head came up and the pucker string activated instantly as I tried to get oriented to know where to jump and what I would be jumping into.

One last great blast (I'm sure at far in excess of the redline) forced the nose down so that he could recover and we bee-lined for home for the day, both of us satisfied that we'd done more than our share of that stuff!

The moral of the story is: no more than a 3 turn spin (per the book) and keep your nose down using air blast if you have to.

I had a flat-spin problem with a stock Goldberg Jr. Skylark I once owned. I acquired it from a friend who was about to throw it away, took it home and completely refurbished it into an attractive little birdie, with a Cox TD.09 in the nose. To counter the added nose weight, I had to mount the receiver battery way aft, behind the trailing edge point.

The little Jr. Skylark flew like a Scat Cat on that engine, and impressed everyone with its smoothness and spunky attitude. Only problem was whenever it got into a spin, there was no hope for it. It would go flat, and spin all the way to the ground under power (no throttle!!), like a falling maple seed, screaming all the way down. All the stick stirring in the world wasn't enough to stop it.

Funniest thing you ever saw. It never got damaged, because it would hit the grass on the gear and just sit there in the dandelions while the engine steamed and hissed and cooled down.

One day I crunched the rudder putting it back in the "boot" of my "lorry", so I pulled the rudder and put on a bigger one. The J.S. would still flat-spin, but now I had enough rudder authority to pull it out if the altitude was there. I know without a doubt that if I were to have moved the firewall back and put the battery up where it belonged, this anomaly would have been chased away for good.

This angular momentum phenomenon (mass at the end of a moment arm) is why airplanes with tip tanks get spin tested with the tanks full.

While I'm posting, thanks to everyone who contributed to the Norvel thread. I found the suggestions useful (though I remain skeptical about the neoprene stopper bit -- even so I only use an electric fuel pump now). My Big Mig .061 still doesn't have a reliable idle, but I'm getting closer. I'm doing touch and goes now, with my Sureflite 1/2A Cub. Another few tanks and maybe I'll be taxiing out to the runway....

Jim Braunam reported having trouble with a House of Balsa AT-6 after having powered the airplane with a Saito 30. About 10 years ago, I was flying this airplane with an HB .25, so I have some experience with it.

However, I never had any trouble with the airplane spinning in the way Jim's described. I suspect what's going on is that the motor is too heavy and that once the mass of the motor has been set in motion by a spin, that the controls do not have sufficient authority to overcome this inertia. Sam

This is to all who have purchased my "Tiny MOO" plans. The plans call for a Speed 280 direct-drive motor. The plane has been tested with a geared motor, the Max #1 (#22904) by Dymond. It is a lighter motor that runs at lower current - still enough power to fly well and LONGER. < http://www.rc-dymond.com >

This model should also work well with the POT 2 and POT 2A series from Hobby Lobby. < http://www.hobby-lobby.com >

Another battery system has also been tried - a 7 cell 270 mAh NiMh pack (the same size as 110 mAh Nicads). These batteries can be purchased from Batteries America < http://www.batteriesamerica.com > for $2.50 each (#AP-270 AAH)

Joe Lewin wrote: "The range of coloured Jap tissue seems very limited...I am building a Wildcat, and need dark and light blue to represent Navy colours. Does anyone have any good ideas for lightweight colouring of tissue?"

I've used Pantone 541 dye (available at good art shops) to get a really nice dark blue. These dyes are particularly useful as they come in a wide range of colors, aren't waterbased and so don't affect tissue shrinkage, and you can get matching felt-pens for touch up or coloring balsa. I just wipe it onto tissue using a paper towel.

Another way to color tissue is to use chalk. Many of us are experimenting with this medium with considerable success. You might want to read a short article I wrote about it in the last Windysock newsletter. You can view a version of it at: < http://www3.sympatico.ca/larrym/chalk.html >

Regarding Floquil and other tissue-coloring techniques. For WWII colors you can't beat using Testors enamels, of the kind used for plastic models. They come in all of the colors used on aircraft of that era.

First stir the paint bottle well, then pour the contents into a larger jar. Use lacquer thinner or nitrate dope thinner to get all of the enamel "vehicle" out of the paint jar, leaving just the colored pigment.

Pour nitrate dope (non-tautening) into the jar. Add thinner to spraying consistency. That's all there is to it. You can do this with Testor's Pla, Floquil, Humbrol as well. Humbrol is a very good model paint. I painted a 1/3 scale Sopwith Pup for a friend. This is one big machine. I believe the wing chord is 15"!! I painted the whole airplane using just three tiny cans of Humbrol.

I don't recommend using an airbrush for painting a model. An air- brush is ideal for painting numbers, letters, roundels, etc. I know that there are many out there who can do a great job with the airbrush; but to me, it is like painting your house with a toothbrush.

You can buy a touch-up spray gun for under $40 that does an OK job. However, a DeVilbiss, which is well over $100, is the only way to go. The difference is night and day. If you plan to paint a lot of models over your building career, spend the money. There is nothing like a high quality tool...right?

I hope to do a separate article on spray equipment, and how to spray. Too many people are intimidated by it, and they shouldn't be. With the right equipment, half the battle has been won.

Deployed air bags may contain residuals of a very VERY poisonous chemical. About the equal of cyanide if inhaled or gotten on the skin. Also, the deployment canister, if full could be deadly, and even dangerous after the reaction, if the chemicals did not run their full course. If it did, residues could be harmless, but why take chances?

Me, I bought a $50 roll of Tyvek five years ago and still have 2/3 of it left despite using it for practically everything. RC

I prefer a muffler that's firmly bolted to an engine. I have the tools to do this to my Norvels, and a real nice muffler for this is the original VA unit. Does anyone have a few that they can spare and if so, how much do you want for them?

Also, my throttling experiments are evolving into the larger than 1/2A sizes, but I need simple airbleed throttles for everything up to a .28. I am soliciting donations of these. I will pay postage for anything in good condition that I can use.

For those always on the lookout for making their airplanes lighter, Radio Shack has Nimh batteries in the AAA size that are rated at 550 mAh. These are not solder-tab types, and you are cautioned not to solder them. However, with extreme care I was able to solder up a pack. So far, on the bench, they deliver 550 mAh as advertised.

A week of charging and discharging has shown that they charge up just fine using a standard overnight charger. Also, my Hobbico peak detection charger works, as does my Sirius Smart Charge that I have in my field box. Today's flying session has yielded total satisfaction, so far. Only a full season of flying though, will prove their reliability -- especially considering they were soldered together without solder tabs.

In Canada, Radio Shack's part number is 23-527. The card advises that the typical charge rate would be 170 mA for 4 hours; and quick-charge rate is 550 mA for one hour. So it appears they had us field-charger guys in mind. Like nicads though, they also take a 50 mA rate for 14 hours as found on your typical overnight charger, and do just fine.

I started building a Facetmobile using foam board. The only problem I've seen with the material is that when I tested Monokote on it, it puffed up from the heat. You have to be careful about the amount of heat you apply to it.

Does anyone know whether the small 2/3 AA rechargeable lithium batteries can be used as a receiver pack for a small glow-powered plane? They have a nominal voltage of 3.4. I know the 800 mAh battery packs can be used, at least by my Futaba receiver. I just received the new JR 610 micro receiver, and do not want to fry something in it.

...Mike, the best way to find out would be to contact the JR people. However, in checking them out for my own informational purposes, I see that they're now hiding behind their "Exclusive Distributor", Horizon. I wonder whether calling them -- (800) 535-5552 or (800) 443-2872 -- would provide any useful information. [JW]

I am delighted with my Clancy Speedy Bee powered by an OS.15 engine. It is the most fun of any model I have ever flown. Turns are unbelievably tight and it loops nicely. But the rolls are very barrel-like so that I dare not do them comfortably at lower altitude. I think I have as much aileron throw as the linkage will allow.

I have been wondering as to whether the differential movement of the ailerons might be a factor. With two separate servos and a computer radio I decided to reduce the amount of differential but lousy weather will delay a test flight. Is this likely to make the rolls faster? Do I really need much differential on a stubby wing like the Bee has? If I remove all or most of the differen- tial, would coupling the rudder to the ailerons be useful?

George Hostler < > amplifies the comment from the previous Posting: "...rubber-power performance suffers very little from high-altitude effects...rubber models do as well at altitude on the same size props and rubber motors as they do down low. [JW] "

In HVAC, (heating, ventilation, and air conditioning), fans are considered constant volume devices. They will pull the same CFM whether at sea level or at altitude. Only thing is, at sea level we are talking about 14.7 PSIA instead of the 11.5 PSIA air density at 7,000 foot altitude. I guess this would be a good explanation why rubber power at altitude does about as well as at sea level.

Have never tried it, but the same would apply to electric power, except convective cooling on the motor would be impaired and need improvement on, because of the air density. (Hence why RV owners wind up with overheated automatic transmissions at this altitude, unless they go for an oversized oil cooler.)

The internal combustion engine does not output as much power as at sea level, the reason being the air density. Air/fuel ratio remains about the same, but the density of the mixture taken in is less potent than at sea level. That's why full-scale aircraft with reciprocating motors use supercharging or turbo-charging to increase the air intake.

Furnaces at this altitude are de-rated roughly 25%, so fire boxes will produce the heat required at altitude. A 100 Mbtu/hr. output furnace will then produce about 75 Mbtu/hr. around here. Thus it makes sense to put a .40 in a .30-size plane; or in small talk, a .20 or .25 in a nominal.15 airplane.

BTW, Gallup is 6,500 ft. altitude. However, because the land is hilly, the area near the hospitals is 7,000, only several miles from the airport. McGaffey Park 12 miles away is around 8,000 feet. However, I am only familiar with flying at 6,500 feet.

To illustrate the effects of altitude on model performance, I recall flying my Top Flite Roaring 20's by Ken Willard (with about a 20" wingspan, Ace Pulse Commander rudder-only R/C and a .020 Cox Peewee at my Grandmother's field in Cresson, Pennsylvania, at 2,400 foot altitude. I wound up putting a 1/8" shim under the leading edge, and it still barely puttered around. When I flew it at sea level, both in Norfolk and Hawaii, it had more than enough power.

(Nice model: I could pack it in a suitcase with a pint of fuel, now a no-no in the airline industry.) The .049 Black Widow can provide enough power for this size model at Gallup's altitude, if you build light (and I mean light) and carefully choose your fuel and props.

SMALLnet Posting post311