Rubber Freeflilght to R/C

[thepilotbruss]

I was thinking that it would be great to use a rubber powered free flight for r/c. It would be self launching and with modern radio gear it would be light enough to thermal very well. Does anybody know where to buy a rubber powered free flight kit like the one pictured below???? Has anybody done this before????? Any help would be appreciated.

Regards, Justin

[BMatthews]

You could certainly do this sort of conversion as you say. But you might want to slightly change the source of your design. That one in the pic looks a lot like the current super duper carbon D box premade in Czechoslovakia BIG BUCKS premade ARF.....

What about something more like an unlimited rubber design? Or an old time Lanzo Stick?

Or you could step back about 10 years and build a Bob White wake from those prehistoric times when Free Flight still used material that modellers could obtain without requireing a dangerous goods permit to order...

I see a 50 to 60 inch span 300 sq in model that uses an unlimited rubber type Warren Truss fuselage. Perhaps not with the LONG motor that these normally use but certainly longer than the typical wake. An airfoiled pylon would house the gear with pull-pull kevlar threads to the tail.

Howzzat? Or did you want something more glider oriented but that had a built in high start?

[thepilotbruss]

The problem I'm having is where do I find plans or kits for a rubber free flight plane. I have done some gas planes, scratch built a couple of hand launchers, and have sloped a couple times a week for the past 2 or 3 years. Are you saying that a good free flight is going to cost me as much as my molded slopers?? From the looks of them there just short chorded built up d-tube wings with a hollow boom for the motor, right? I've got a few JR 241's a reciever and a 150 mah nmh battery doing nothing for me and If I can find a cheap kit or some plans I would like to build it. Obviously I don't know a darn thing about free flight planes so any help is appreciated.

The picture I posted was just one I ran across on the net to give people an idea of my idea. My plane does not have to look like that one. What is an unlimited rubber design or a Lanzo Stick? All I'm really looking for is a light wieght extremely high aspect ratio polyhedral wing 60-80 inch and a hollow boom with the rubber and prop. Where can I get this without spending alot of bucks? I don't mind cutting my own ribs if I can get plans.

Thanks for your help, Justin

[BMatthews]

I may be able to dig something or at least some suppliers up. In the meantime try Flying Models plan service.

[dephela]

Greetings,
Here's some help. You're looking for F1B planes, Wakefields. Gorban, and Vivchar are good keywords.
http://w-hobby.com/
http://www.freeflightsupplies.co.uk/
http://www.aeromodel.com/TM/E19264T7
http://flyfree_2.tripod.com/shop/f1b_igor_vivchar.htm

You might also be interested in F1A Nordic "gliders":
http://w-hobby.com/
http://www.vasi.scana.com.ua/catalog.html
http://www.algonet.se/~friflyg/Prislista_Stamov.htm
http://paireli.s5.com/products.htm

Have fun!

Dennis

[markdrela]

Originally posted by thepilotbruss
I was thinking that it would be great to use a rubber powered free flight for r/c.

Yeah, you can do it. But it will be a rather lame RC thermal model. A crucial feature of a good RC glider is "penetration", which is the ability to fly fast while retaining a good L/D. This allows you to run back upwind after a thermal climbout, without losing too much altitude in the process. FF models have no penetration ability to speak of, since they don't need it.

Penetration ability requires airfoils with low camber, usually in the 1.5-2.5% range. FF airfoils seem to have more like 4-6% camber, and will sink fast if the speed is increased significantly (say to twice the min-sink speed). They basically want to fly at one slow airspeed close to stall.

A more interesting experiment would actually be to go the other way: Use a low-camber DLG airfoil and put it on an F1B, or better yet, an F1C model. This would substantially increase the altitude gained during the high-speed climbout, which may more than overcome the slightly higher sink speed of the low-camber airfoil. If the FF model has flaps just like a DLG, you may get the best of both worlds. All the flapped FF airfoils that I've seen were ad-hoc adaptations of existing high-camber airfoils, and hence unlikely to be optimal. Modern DLG airfoils are designed at the outset to work well with flaps.

[thepilotbruss]

Thanks for the links Dennis. The picture below is exactly what I was looking for. Just instal a couple servos to control the tail and bang a self launching silent flyer. I think a full flying rudder might have to be used or an increase in size might be needed.

[thepilotbruss]

Mark, your right about the under cambering of the free flight planes. I knew that free flight planes were supposed to fly slow but I did not know how slow. They are very high lift and slow flying foils. I think a bagged polyhedral DLG wing is the way to go. I would like it to be about 1.75 meters though, so I might have to make one myself. (I don't bag yet so it would be built up). Fortunatly I can order an F1B from w-hobby without the wing.

This is the exact foil used on the plane pictured above.

Anybody Bag 70-80 inch HLG wings out there??

[BMatthews]

Ah, I thought you would have already realized that these would NOT be a good windy weather flier. Guess I should have read a little more between the lines when you professed your unfamiliarity with these types of models.

There's a reason why F5J models and the other speed 400 electric sailplanes look like they do rather than like those Wakes with motors on the front.

I think if you're looking for all round performance you'd be better off with a speed 400 electric sailplane. But if you wanted to wow your flying buddies on calmer days then a rubber powered Bob White Unlimited would bowl them over for sure. On a calm summer's evening they would be able to float on the last wisps of the day's thermals like nothing else.

Here's a site with some ARF stuff. I've linked to the page with the $622 ARF Wakefield..... http://216.35.184.47/f1b2.htm

Or if you want something with character then there's this OT Korda.... http://freeflight.org/illustrated/pictures/600/dcp01072.jpg

And here's someone with an unlimited rubber ship. Note the Warren truss construction to the fuselage. These models often take up to 2 1/2 minutes just for the motor to unwind. Slow climb though.... http://freeflight.org/illustrated/pictures/600/cmcd0118.jpg

And finally George Perryman with one of his "unique" unlimited models... http://freeflight.org/illustrated/pictures/600/hn_007.jpg

If you're interested in any of these sorts of models then I can steer you a bit more. If you're just looking for a new launch method then you may as well stick with electrics. You'll need a larger model with a fair chunk of rubber to get a decent climb without learning the wizardry that goes into modern wakefield flying. And, trust me on this one, you DON'T want to see what 14 strands of 1/4 wide rubber does to a fuselage that's not protected by a blast tube. Even the carbon fiber tubes on modern wakes have been known to split under the shock of a fully wound blowup.

If nothing else at least you and a few others have seen a little slice of the other side of the fence.

[thepilotbruss]

Thanks again for the links guys. I think I know what I need to do now. I have an original design built up poly (64 inch) wing and a Bowmans Hobbies Javelin wing collecting dust. All I need is a F1B or simmilar fuse, motor and folding prop to make this a reality. I think the foamie wing would be to heavy but my built up is extremely light so it should work well.
I'm surprised at at the expense of some of these models. (some approach $1000). Although you can get small ones (30 inch) for about $70-100 dollars. However they only come with free wheeling props (not folders) and would not have the juice I need to carry the extra weight of added servos, battery and Rx.
So.... my question is "where can I get a powerful fuse. motor and folding prop for a reasonable price? Your probably right BMathews that I need one of decent size since I have no wizardry knowledge of freeflight planes. I don't want to have a built up truss fuse, it just is'nt as cool looking (we all know how important that is LOL).
Thanks all for letting me think out loud here. I really want to put together something that will make people stop and wonder. This might even turn out to be something for people that have a handicap but want to get into hand launch gliders.

Regards, Justin

P.S. The model below sells for about $270 and would be a perfect candidate for this project........I think.

[BMatthews]

Nope, wrong choice. Coupes are set up to use only 10 grams of rubber. This is the MOST DIFFICULT rubber event going if you look at the rubber versus model weight ratio.

Forget the full kits and just go for a premade front end and roll your own fuselage..... literally. It's relatively easy to roll 1/16 balsa around a conduit form and then just make the rear boom up from a carbon tube shaft and a block balsa adapter.

You're looking for a premade wakefield front end and prop or an unlimited front end or prop. The motor will be a compromise of 10 to 12 strands of 1/4 flat about 24 inches long between the hooks to hold a 32 inch long motor. This would give you a good climb to about 200 feet with a 10 oz overall model. The sticky bit is that this includes about 3 oz of rubber. You'll learn to build light like you've never built before.

More later when I have more time.....

[jay flay tway]

Just a thought from a newbie.
A continuum...

a thrown rock
a motorized RC plane
an RC glider
a free-flight glider

I love it all...but there's something magical about free flight. It's in some way the most truly flight, the plane must be tuned better and you can really see lwhat the wind does to it, undeterred by your thumbs.

Those who love flying, love anything that flies.

[ejett]

One of the model magazines had a rubber powered RC conversion in it. I wish I could remember more about it. It seemed to be a pretty novel adventure.

So, it is possible and it has been done.

EJ

[claymeyer]

Here's a model (the ElJoy) from Hobby Club (http://www.hobbyclub.com) that looks a lot like the freeflight models you've shown. It's an ARF, and much cheaper than what you've been looking at.