I am trying to build a Guillows Dauntless with a 31" wing span. I have searched all of the messages for relevant info and have come up with several previous suggestions on engines and batteries.

Problem is I dont have the foggiest of what any of this means. I have built many guillows, but have never tried making an RC version. I have a new futaba 2 channel R/C with servos and such. I am also wondering if I can run the servos off the motors battery, or should I keep the bundle of batteries that came with the controller?

Here are the acronyms I need help with as well....


------------------------------------------------
I found help on converting rubber to rc in the free articles on rc microflight magazines site. They did a 30" dumas bearcat. I' m currently working on a Guillows 3/4" scale (27 5/8" span) Spitfire.
Rudder, elev and ailerons. Speed 280 geared. I hope it flys, i'm going as light as I can, punching hole in ribs, possibnly tissue. hoping all up she'll be around 12 OZ. Go lithium! but research first..Ebay has guys selling converted lions and chargers that he has tested and has no probs with.



Speed 400, size mtrs.would be ideal. The added wt. would allow You to fly in some wind, like My old slimers did. 7-500ar or 7-600ae would do the trick. My heaviest cat was 32oz, w/a then micro- radio of 6oz. Flew for two yrs. Good luck, the design is on your side.

I am flying a Guillow's PT17 with GWS EPS300C geardrive, GWS 9X7prop,8-cell 720mahAAA pack Hitec 555 and 2-HS-55 servos,Pixie14 esc. I beefed up wings and added dihedral, top wing is at zero incidence. Total weight 17.4oz. ROG take-offs, 10 minute max duration at average 3/4 throttle. I think that the above power system would be about right compromise of power versus weight for the Dauntless, Hellcat, etc. I plan to use the above for my Dauntless kit. You could use a lighter 300mah 8-cell Nimh pack for 5-minute flights.

ERG:

The only acronyms I saw in your post were "RC" and "ROG." And your use of them indicated you already knew their meaning. Did I miss something?

Bill.

erg,

If you need help with all the abbreviations and cryptic terms then most of them are product types or names e.g. Hitec 555 receiver, HS-55 servos, Speed 280 motor.

You'll have to be a little clearer about what you need.

Steve

Let me give it a shot at a few of the items you may be questioning. First, Dumas (kit manufacturer) of a bearcat (model) with a 30" wingspan. Next, 3/4" scale (3/4" to 1 foot scale) Elev - elevator. Speed 280 geared is a Speed 280 electric motor with a gear reduction. Punching holes in the ribs - put holes in the ribs to remove material to lighten the airplane. Go lithium (batteries) - lion means lithium/ion batteries. Slimmer - glow powered airplane. 7-500ar - 7 cell/500mah battery or 7-600ae (typo) 7 cell/600mah battery. Heaviest cat (bearcat model). GWS EPS300C geardrive (GWS electric motor with a gear reduction).
Don't really know what you refer to acronyms. Not to be condecending but is any of that what you want to know?

I guess acronym is not the best word for it. Thanks tippie. I just needed all of the battery and engine jargin (thats the word!) explained.

So from the info I have read i believe I should get a 280 with gear reduction and a 7 cell battery? Does this make sense? Does anybody know of a engine battery combo with everthing I need? Or do I have to part it all out?

thanks!

erg, just for information it's "jargon" and we call them electric motors not engines.

It's probably easiest to go with the GWS EPS300C setup, which is similar to a geared S280. Lots of people sell them complete with battery, speed controller (which you'll also need) and propeller. Try somewhere like Hobby Lobby.

2 channel RC is not enough, you really need 3 channels. Rudder (or ailerons), Elevator and Throttle. If the servos you have are standard size they will be WAY too big for that plane.

You'll want to be careful about the weight. In my experience Guillows kits often contain very hard, very heavy wood and build up really heavy. Not good for flying.

BTW unless you're pretty experienced flying RC a small warbird conversion will be a real handful. I'd get something much simpler to learn to fly with first while you're building the Dauntless.

Steve

thanks steve. I decided to do the warbird (against all advice), because I enjoy building the guillows, but have no where to store them (had to throw 5 in the garbage last time I moved). I figured if I were just going to throw them out, I might as well try to have some fun while I destroy them.

Is their anyway to get around the throttle? I just realized that today when I bought the 280 gear reduced and all the fixings + charger for about 80 bucks at a local hobby store. Is it reasonable to try and go 'on off' with the throttle or is that just crazy?

Even to have an on/off switch you still need a channel on the Tx to switch it. Just having a manual On switch and letting the motor run until the battery goes flat is not a good idea. When the battery runs low on power the plane comes down and unless you have landing gear it stalls the prop and either burns the motor out or damages the gearing.

Anyway you can't run the Rx and servos direct off a 7 cell motor pack or you'll kill them and carrying a motor pack and a 4-cell Rx pack would add too much weight again. A speed controller will have a BEC feature which reduces the voltage from the motor pack to a suitable level.

What flight controls are you using ? Elevator I guess but are you going for rudder or ailerons ? Ailerons work better on low wing planes without much dihedral but they're trickier to build and set up.

You may be better making a static model. Mounted on a nice plinth with a working prop and wiggling controls it would be quite cute.

Good luck anyway. I'm afraid you might be needing it.

Steve

hehe, too late now. I think I will return it and get a 4 channel. I am using ailerons, and have built most of the model already (custom building the aileron and elevator were the most fun). I was thinking about that 'what happens when the prop stops too. It has landing gear but not that I want to risk ruining my gears. Thanks for your advice!

Steve, sorry to correct he expert, but I think you'll find that an EPS300 is a geared Speed 300 (Mabuchi RS370) motor, not a 280. A much "hotter" little system than the rather docile 280.

Cliff

Thanks Cliff, there's always lots to learn. Obviously I meant "similar to a geared Speed 280 but not very" .

From the figures on the GWS website the motor is actually slightly lower Kv than a Speed 300 though as you say a lot hotter than the weedy little Speed 280. It actually looks pretty reasonable for Guillows sized planes, provided you can keep them light.

Steve

Hey guys, where does the weight come from in these guillows? I am not sure what an average plane with a 31 inch wingspan weights but mine is only running 8 ozs so far. That is the fuselage, wing, all control wire control arms, rudder and elevator. Nothing is covered yet, the wheels are off, and none of the plastic is added (I am only going to use the cowl and the canopy).

Is it just the batteries and servos that bring it up or is 8 ozs pretty heavy already?

8oz is pretty heavy already. Ideally, a plane on Speed 280 power should weigh less than 10oz, which leaves you exactly 2oz for the covering, radio equipment, motor, and battery. It ain't gonna make it

A plane that size should weigh half as much as yours does.

ouch. I was planning on 20ozs. It will be interesting to see if it flies.

Hi erg,
Here's just a little more advice. Download motocalc http://www.motocalc.com. The first month of use is free.

This tool has already saved me tons of money, I just wish I had used it when first doing my Guillows P-40 (28") rubber to electric conversion. The program is a little overwhelming at first, but when doing this type of conversion you can easily spend several hundred dollars before you figure out that you bought the wrong stuff.

To give you some weight specs, my P-40 is weighing in at just under 10 ounces with servos (GWS Naro), ESC (Great Planes C-10), and receiver (GWS Pico 4 Channel) installed. This weight also includes the entire plane being sheeted in 1/32" balsa. With the motor and battery installed it weighs around 14.7 ounces with a 15 ounce wing loading. This is still fairly heavy, but not too much so.

A caveat to building the Guillows kit is that their balsa is very dense (ie: heavy). Another is that each parts sheet is of varying density which means that things like one wing half will weigh more than another. Just be aware of this and sand / build to compensate. Replace their parts with parts cut from less dense balsa where feasible.

For my plane I originally thought the Great Planes T-280 motor, which is a Mabuchi RC-280SA-2485 in disguise, would work. MotoCalc proved me way wrong.

After some measuring for the proper airfoil parameters etc and plugging these numbers into motocalc, I found that Graupner speed 300 6V (#3306) with a 4.5 to 1 gearbox would work nicely. (Don't use the 7.2 V version of that motor, it is completely different and won't provide enough thrust to get your model off the ground)

For electric power I'm using a 6 cell 650mAH NiMH battery pack. You might look into either lithium poly or lion pack which is much lighter for the same power. Cost from eTech or Kokam is comparable or even cheaper than the Nicad or NiMH packs. At the very least don't use Nicads, way too heavy.

Another motor possibility are the GWS EPS300 systems, although these seem to be disappearing from shelves. I get the feeling that GWS will stop making them soon. On the other hand, the GWS EDP-400 direct drives provide some nice power.

One last thing, at every point in the building process think about what you could do to make it lighter. With these small electrics weight is the greatest enemy. Use lightening holes, change the guillows supplied balsa with something less dense where possible. When balancing, instead of adding weight to one side, look into removing weight from the other, or even try to move the battery around to reset the center of gravity (CG).

I can't say this enough, get motocalc, run the numbers, then research, ask a bunch of questions, run the numbers again, then buy what you need.

Good luck!
Chris.

Thanks, I think I will return the 280 and get the 400. I have a 7 cell 600 nicad battery (ouch). So that should still be plenty for the 400.

I cant believe how complext this is. when I started I just hoped that my elevator and ailerons would work! Amazing how easily these things fly with a rubber band and how hard it is to get them to move with a motor.

I will also check out that program.

just ran the program. It also says a 400 is needed. THANKS! everything else seems okay.

................Erg..............Getting them to move with a motor is simple! Almost as simple as with rubber power. It is the radio control that makes it so complex. Electric free flight is a ton simpler, lighter and cheaper than R/C.

Almost finished. I am still way underweight too. looks like its going to come out around 18ozs. Thats with big servos too. My ailerons are pretty small but I think they will work. Not looking for acrobatics here. I am still trying to get the right prop adapter for the 400. I think I have finally ordered the right part now though. I will try to post a picture of it this week.

Well, just the prop now. Here are the pictures. Really didnt take that long. Most of the time was spent trying to figure out how to do the ailerons without any visible cableing. Bet it will crash reall pretty....

and another pic....

Looking good .......So what is the all up weight and wing area?

The final weight was 19ozs.

Wing area (average wing width by length) is 312in2.

I may need to add a little weight to move the center of gravity back a little. Right now the balance is about an inch too far forward. Just got the prop adapter today to. I put a nice master air screw prop on it. Not sure what you call (7x9?) it but it has 5 inch blades.

here it is with prop in place, on the charger. You can also see there are no external controls for the ailerons now.

Well it flew, it felt a little underpowered but all of the control surfaces worked better than expected. I got four launches with short flights before the screws holding the motor to the mounts stripped out (from nosing into the tall grass). Now I find the weak links in the old chain....