I have a hitec feather flight pack and want to install it on a freeflier which already has a 5x270mAh battery pack and a 35watt motor. My q is: Do I need a Y connector coming off the battery so that leads can be sent to the Rx and to the motor? Or can I just leave the leads I already have going from the battery to the engine and just make another set of wires go to the Rx? Or do I need a separate power source/batt pack for the Rx?

Thanks to all who can help

Jim

Are you planning on adding a speed control to the motor?

If you plan on simply running the airplane at full throttle until the battery runs down, don't. What will happen is the battery will run down, you'll lose control, and crash.

All the speed controls available in this size range have what's called a "BEC," or Battery Eliminator Circuit. This means that power is automatically provided from the main battery to the speed control.

Of course, this is completely ignoring any of the other problems you'll encounter when converting a free flight airplane to R/C...

Thanks mkirsch!

It looks like going w/ a BEC is the way to go. Re other problems w/ converting free flight to r/c... any suggestions? Maybe a website you think would be helpful?

Thanks a bunch!

Have never done such a conversion, but what control surfaces do you intend to use... R and E?

Hi Sierra. I plan to use R and E controls to start. I have a Troll-35 motor from Hitec that I tried in a Guillow's Spirit of St. Louis. Too heavy (nose diver). So I took my Guillow's Arrow plans and copied the wing plan to 1.5 times the size and built just the wing. I am keeping the tail section the same since its relatively big (i modified it so the rudder and elevator have hinges). I am still thinking about the fuselage which I will probably start on tonight. Probably going to be just a simple box shape to hold the engine, servos, Rx, switch, etc. and then taper back to the tail section. I think I will try just connecting the box part of the fuse to a balsa 1/4" balsa stick and run that back to the tail. Any thoughts or pointers are greatly appreciated.

Well, basically it sounds like you're describing a pod and boom fuselage.
I know you are supposed to "build to fly and not to crash" but I would recommend you use an arrow shaft or a carbon tube from your local hobby shop rather than the 1/4 inch balsa for the boom.

What is the wing span of the new wing? How many sq. in.? I think weight may possibly be your enemy here.

Not familiar with a "Troll-35 motor" so have no idea what size motor it is. Watts should tell me something, but it doesn't.

Have you flown RC before? What radio do you have? What is your motivation to convert a F/F model?

Sierra Gold

Hey, thanks for the input Sierra. A pod and boom fuselage sounds right. A carbon rod? I know where the aluminum rods and metal wires are at the local shop, do you think they might be near those? Anyway, the reason I am going w/ the pod and boom shape is because I figured it would be a good shape to use to cut down on weight.

I finished this reply and found its longer than I thought it was going to be - sorry for that. Here's a quick reply to the q's you had:

The new wing span is 235 sq. inches. The Troll 35 is a 35 watt motor (I think. I also think its comparable to a 400 type). I have never flown r/c before. I have a Hitec Focus 4 Tx. My motivation to switch to r/c is that I lost a plane and am tired of climbing trees/ using pool cleaning poles.

Here is my saga:

I started out w/ a Guillow's Arrow model (kit 702) that has a polyhedral wing. I put a teedee .020 gas engine on it. I took it to a local field and tossed it downwind (there was a very slight breeze). It took a big left bank as it approached a tall green hedgerow (it was really cool to see 2 white exhaust streams coming off the engine as it banked past the big long hedge). It banked and turned then passed me, then it proceeded to climb and climb, finally going way out of the field area I was in. When it was a few blocks out of the field area, the engine finally died. It started back toward the field and it looked for a second like the wind might carry it back, but it quickly nose dived streets away, never to be seen again.

So I rebuilt the wing and tail section of the Guillow's Arrow from the plans I still had and put in a Hiline Mini-6 (one of the electric motors suggested in the Arrow kit; its a 4.6 to 1 geared shaft on a Micro-4 motor; draws 2 amps at 3 volts giving 1.5 oz of thrust). I put the wing and tail section on a very simple fuselage that I put together. I guess its not really a pod and boom since the boom part is 4 balsa sticks coming out of the back of the pod and tapering together at the end where the tail is. A side view of the pod section w/ the top 2 sticks coming out the back literally looks like:
__._____________________
\_______|

the other 2 balsa sticks come out of the back of the pod and taper up to meet the end of the top 2 sticks (couldn't put that in the drawing since there's no ascii that tapers up that narrow). The nose slants way down at almost the same angle as above, and I put a sq. 1/8" stick of balsa across the front of the fuse (where the period is in the drawing above) to give the wing more lift. The wing attaches with 2 rubber bands that cross over the wing and attach to the fuselage. It is a good slow flier but I think its too small for r/c.

So I looked in the Hiline catalog and saw the Troll-35 which is their 2nd biggest electric engine. I believe it is a 35 watt motor. It draws 8.2 amps at 3 volts producing 2.9oz of thrust at 9300 RPM on a 5.5" prop. It draws 11 amps at 4 volts for 4.1oz of thrust at 10,800 RPM on the same size prop. The package I got came w/ 5 270mAh NiCd's and I plan to use them for both the Rx and Tx. The Tx is a Hitec Focus 4.

I have never flown r/c before but decided I should so that I don't lose any more planes in unknown backyards blocks away. When I was flying the rebuild of the Arrow I made w/ the Mini-6, it ended up in trees requiring climing and the use of long (often tethered together) pool cleaning poles. I wanted to be able to avoid that and an r/c setup seemed like a good idea.

So I knew I needed a bigger plane than my modified Arrow that I have been freeflying with. I got a Guillow's Spirit of St. Louis (kit 807) and put the Troll-35 in it. I went to freefly it and it totally nose dived. I took off the wing (which is 34.5" long, area=190 sq in) and put a pod under it and tapered fuselage w/ the same simple design I used in the modified Arrow. Alas, it nosed again.

So I decided to go w/ a blown up version of the modified Arrow. I xeroxed the Arrow's wing at 1.5 times the actual size and have rebuilt it. Its wingspan is now 53" and it has an area of 235 sq. inches. I am going to keep the same tail section of the original Arrow (modified to have hinged elevator and rudder). The elevator is 11" and has an area of 40 sq. inches. The rudder is about 3" by 3". I plan on putting the engine pretty close to the where the wing is going to be since I'm worried about the nose heavy problem. I hope I have a little wiggle room since I plan on using the same rubber band technology that the Arrow uses to attach the wing to the fuselage.

What I'm wondering is - how long should the boom be? I don't think I'll use the same tapered 4 balsa stick configuration since I figure it might be easier for the servos to hook up to the tail section if the only thing in the way is a boom coming out the middle of the back end of the pod.

Any ideas. All suggestions are welcome. Sorry for such a long post.

Well... That was a mouthful.

If you don't enlarge the tail feathers, the boom length should increased by about the same percentage as the wing was increased I believe. I'm no designer, but there is a relationship between tail feathers and wing span.

The reason I asked about your RC experience and your motivation for this conversion is that there are a number of really great trainers out there that might help insure your success.

The GWS Slow Stick is one and costs $35 including a motor. You have the radio, so you are well on the way expense wise. The SS is an aluminum rod fuse and foam wings and builds in about 6-8 hours. Very good flier.

You might do well to start there and leave the "custom hot rod" until later.

Just my 2 cents

Sierra Gold

Thanks Sierra By tail feathers do you mean the entire tail section or just the moveable parts? I may go w/ the SS you suggested but since I already have the wing built I figure I'll give my scratch a try. Thanks for all your input. Very much appreciated

The entire tail feather volume.

As I crudely understand things, for a given plane design there is a relationship between the tail feather volume, boom length and wing volume. If you increase the wing volume you either increase the tail feather volume proportionately and leave the boom length the same or you can adjust the boom length and leave the tail feathers the same. (Longer boom gives the same "authority" to same size tail feathers with increased wing size.)

I'm sure this has some practical and design limitations and that I over simplify a very complex engineering excercise.

Good luck, whichever way you decide to go - or both.

Sierra Gold

Thanks Sierra!

I built the pod last night. Its 1.75" x 1.75" x 8". The wing is 53" x 4.5". I was going to make the boom 19" but w/ what you've told me, I think I will make the boom 21" or 22". Thanks much

Guys, the basic relationship is that the stab should be 1/3 the size of the wing. I would scale up all parts of the tail along with the wing. If you went with the SS you would be flying your first RC right now. It is a great flying plane and the price cant be beat.

Have fun what ever you do, John Smith

Thanks John - I think its probably a good idea to scale up the tail. I'll give it a try if the one I've got built doesn't work - or more likely I'll go w/ the SS.