GPS

I have a really old sailplane I'm thinking of modifying/upgrading and would love some advice. I made it over 30 years ago, scratch built from plans from the old RCM magazine and only flew it a couple of times. Its got some left over dings from those days (when I didn't know what I was doing), as well as hanger rash, so needs some TLC. It's got a 3m wing span and originally was just 2 channels (mechanically mixed V-tail rudder/elevator) with a really old heavy radio - long gone. What I'd like to know is how to modify the wings. I'm planning on adding ailerons, flaps and spoilers (for manoeuvrability, and because we have a short field surrounded by farm land - corn and potatoes can be nasty). Can anyone tell me, or point me to a source telling me dimensions and positions of these control surfaces for a glider? I think I will have to cut the ailerons out of the trailing edge and or build them in so as not to alter the airfoil or aspect ratio.

Tom Nied

GPS, it sounds like you have a "hangar maiden" that was originally designed as a 2 channel. Why not just update its radio, servos, and battery and just fly it as designed? I've got a Radian and as a 3 channel, I'm having a great time with it. Just a thought.

scaflock

Before we consider any mods to suggest I for one would need some more information on the wing itself. Is it a poly wing or regular dihedral? Flat bottomed air foil or something faster? A picture or two would be a great help in coming up with suggestions for you and instructions on how to go about them.

Jeff

GPS

Wing is flat bottom, regular dihedral, slightly tapered. Aspect ratio is about 20:1. I'll try to take some pics, but may take a while. My house is being reno'd so everything is a major mess, and most everything is in the garage.

Our club has a short field and it's almost always windy. I've flown a 2m rudder/elevator electric glider, and it wasn't easy to get down on the field. Usually I fly glow, electric delta wings and 3D foamies. If I don't make this thing more interesting (experimenting with spoilers, butterfly mix etc. sounds fun & educational), it's going to remain a "hangar maiden".

GPS

Here are some pictures. As you can see it needs "some" TLC. Good thing building season is long where I live.

qldviking

personally i'd just add spoilers and modernise the tail system.

GPS

Modernize tail system?

qldviking

sorry, use electronic mixing rather than mechanical for the V-tail

GPS

Yes, was planning on doing electric mixing. Thought maybe you meant that V-tails might not be as good as conventional (they are OK, aren't they?).

How would you add spoilers? How big? Where on the wing?

JaytheRatter

GPS,

Your plane looks like the Specialist "V" by Kevin Flynn. Glad you are going to fix it up and put it in the sky. That's where it belongs. Do you still have the plans? V-tails are fine. Some say they have less drag than a conventional/T-tail designs. With affordable computer radios, mixing of the V-tail is no problem. I agree with gldviking, just add the spoilers. I think you will find RES a lot of fun. If you do have the plans, you could always build another set of wings with flaps and ailerons.

You would add the spoilers just behind the main spar. If your plane is the Specialist, I would start them at the rib where the sheeting ends. Looks like the fourth rib. And would go out three to four ribs. You don't need a lot, they are very effective. You could use 1"X1/4" TE for the actual spoiler flap, or something like that. You will cut out the ribs to except the spoiler so the spoiler would sit following the contour of the ribs. Sorry for the choppiness, it's not as hard as I'm making it sound. I could post some drawing if you like.

You will have to decide how to actuate your spoilers. The old school way with string/thread or with the servos in the wing. Advantages and disadvantages to each. Maybe others out there have a thought as to the best route to go with this plane. If the wing is thick enough, I'd go with the servos in the wing. Nice to have positive control, servo linked directly to the spoiler.

When I know what you plan to do, I can give you a little more detail.

Tracy

qldviking

the V-tail on your glider look to be large and should be quite effective. As for hooking up servo's to spoilers I would look to uyse the slimline wing servo's like the hitec HS-125 or or the jr equivalent, with over 40oz of torque will be more than adequate for spoilers.

GPS

After some digging in my messy garage, I found the plans - it is a Specialist V.

Spoilers sounds like a good idea. Tracy, I'd appreciate it if you could post some plans.

JaytheRatter

Sure thing. Give me a day or so. Have a couple of things going on right now. I have the stuff ready, just need a little time to post the pics.

Tracy

Currawong

Grouse ship. Should look great in the air.

I agree with the fellas - spoilers would most likely be sufficient mod - along with elec mix v-tail of course.

If you want to be elegant, you might consider setting up so you can mix some asymmetric spoiler with rudder function to assist in tightish turns . . .

GPS

Another idea- would anyone recommend adding an electric motor (likely brushless outrunner and lipo's)? If so how many watts per kg (or lb if you prefer) do you need for a glider?

qldviking

Y ou could electrify it, but personally I wouldnt. To do so you would be looking for approximately 80-100 watts per lb to get a reasonably good climbout. In that range I'd also look for a motor with a low Kv rating (rpm/volt) that can swing a bigger diameter prop. I'd also look for a motor esc to run 3s lipo or 4s at most. there plenty of motors out there to choose from. Another option that may be worth a look is to use a topmounted power pod, which is removable, that would give you the option of powered/unpowered.