Conversion of Free-Flight and Rubber powered ?

[solentlife]

I see some absolute gems online ... ebay etc. that I would love to try and convert to electric ...

In the 20" and up range ... from Guillows, Dumas etc.

How many have done it ? What modifications did you do ? I assume motor mount and control surfaces need to be sorted to take our gear ... is it too much hassle to convert ?

I'm particularly looking at a 30" rubber powered Hawker Hurricane at moment ..... but it's very thin stick and tissue build ..

My thoughts are to whether addition of lightweight 3mm foam in places could do the trick or just addition of 1/16th balsa where needed ? Plus opf course a decent motor firewall ... tray for battery ...

Nigel

[JetPlaneFlyer]

i used to fly that sort of balse stick and tissue freeflight stuff. I've got a conversion of a 30" span freeflight Skyraider halfway done (been halfway for over a year). i'd say that the sectret of success is to keep it very light.

With the Skyraider I figure that by using sub micro servos, a 10g outrunner, micro rx, 10A ESC and small LiPo I can build it within a few grams of the original rubber power flying weight. By keeping it light then the flying speed will be low and the momentum when it meets the ground will also be low, there will be no need to start adding reinforcement all over the place. The structure can remain exactly as the designer intended.

The Skyraider design is the one you can see Mike Stuart holding on the home page of his web site: http://www.ffscale.co.uk/

[JetPlaneFlyer]

Here's the what I've got for the Skyraider so far, tail surfaces are just about done but not in the photo. You can see that I've added ailerons into the wings and the plane was to put a sub-micro servo in each wing to operate them.

[mclarkson]

I keep toying with the idea of a rubber-powered RC plane.

[JetPlaneFlyer]

Originally Posted by mclarkson

I keep toying with the idea of a rubber-powered RC plane.

I've seen videos of a couple, here's one:

YouTube Video

Although it's a great novelty I don't think it really has much to offer in practical terms. The one in the video uses no less than 32 strands of 1/4" rubber and has to be wound with a power drill That's going to work out real expensive for contest grade rubber and the motors don't last very long before the rubber starts to break. It's also messy because the rubber needs to be lubricated. It takes ages to wind and at the end of all the hard work you get a flight time of maybe 100 seconds.

Steve

[rreid7]

I converted an old Sig Monocoupe 24" free flight kit to 3-channel RC a couple of years ago. I used a 10 gram brushless motor, 10A esc, 350mAh 2S Lipo, and two tiny 3 gram servos for rudder and elevator. I mounted the servos in the "cockpit" with carbon fiber rods back to the control surfaces. Battery and esc were under that, and a belly hatch for access. The engine cowling is held on with magnets for access to the motor. The motor and RC gear definitely adds weight relative to rubber power, but the plane flew pretty well. Not quite a floater anymore though. I still have it, and will get back to tweaking it when I catch up on other projects.

[solentlife]

There are some absolutely beaut small models out there ....

Will seriously look now for best to do it with .... nice Hawker Hurricane on Ebay ....

Nigel

[stevecooper]

Anything can be converted, Just say'in bubsteve

[kenchiroalpha]

Hi
Heres a very good site for some excellent kits for rc conversion projects
http://www.easybuiltmodels.com/
Take care dear friend
Yours Hank

[kyleservicetech]

Originally Posted by JetPlaneFlyer

Although it's a great novelty I don't think it really has much to offer in practical terms. The one in the video uses no less than 32 strands of 1/4" rubber and has to be wound with a power drill That's going to work out real expensive for contest grade rubber and the motors don't last very long before the rubber starts to break. It's also messy because the rubber needs to be lubricated. It takes ages to wind and at the end of all the hard work you get a flight time of maybe 100 seconds.

Steve

Yeah, I did some investigations on rubber power propellers for launching sailplanes in the mid 1980's. Found that rubber power stores no where near the energy that is available in a decent Nicad battery. Now we've got brushless motors and LiPo and A123 cells that are far better than those old RC2400 Nicads.

[mclarkson]

I wasn't thinking of it for anything serious. Maybe putting an ultra-micro brick on one of HobbyKing's cheap rubber band powered models or somethin'.

Just for giggles.

[earthsciteach]

Timely post, Nigel! I am back to eyeing up the Guillow's 24" Super Cub that I started building so many years ago that I don't remember building it. It ready to cover and glue the major parts together. I must have really been thinking ahead to preparing it for RC all those years ago, since I didn't finish it off.

I was also browsing ebay last night. There are some beautiful stick and tissue models for sale.

[kenchiroalpha]

Hi
Heres some food for thought
http://www.aeronutz.flyer.co.uk/
Take care
Yours Hank

[Big Johnny]

I converted a Gulliows 24" Super Cub 95, useing the guts out of a 4-Site. I converted th brick, so I could use a 2S and 7 Amp ESC. I used Power Up Sport 180 10gram brushless from HeadsUpRc and a 2s 360 lipo. It is 4 channel. The hardest part was modifying. The wing for ailerons. I also used carbon fiber spar. Covered in Esaki Colored tissue and clear coated with Krylon Acrylic Clear. It flies awesome. I going to build the Cessna 170 next. Oh. By the way these kits are now Laser cut.

[solentlife]

So what about we start to list up generally available bits and bobs suitable for the average Guillows / Dumas / Kiel Kraft kits of the 20" and above ?

ie Servo size .... motor .... battery etc. ?

(trouble for me is USA sellers are out for me ... so can we do it on Hobby King parts ? I'm not saying we use HK ... but everyone has access to their online listing and we can always cross to another site once we know what we are looking for).

Might be an interestiing exercise ... those who know what can be used passing on good info for those interested to have a go ...

Nigel

[earthsciteach]

Big Johnny - would you happen to have any pics of your work? That is the exact model I hope to convert to rc. What servos did you use? How did the PowerUp 180 work for you? I've bought a handful of those and they always burn out the windings really quickly.

[Big Johnny]

I used the linear servos from the 4-Site. I try to keep the amps below 4. The prop is a 6x3 pulling a little over 3.5 amps. Didn't take no pictures, but will do a buildlog on the 170 or Beaver, whichever I decide to do. I got my tissue from Dare Design. The 180 power ups will croak with over 5 amps.

[E-Challenged]

Converting small rubber powered scale models to electric powered RC is a real challenge suitable for those who have tried it a number of times and have gradually learned to build light and accurately enough, choosing the right power and RC hardware, while also developing essential tail dragger flying skills and reflexes. These models tend to have to fly fast and are prone to stall and crash. Landing gear takes a beating so needs to be judiciously beefed up. I always recommend spending a few more bucks and starting with a larger kit designed for electric powered RC such as those available from Pat's Custom Models or Mountain Models/Laser Arts. Here is the sticky on RCG with links to hundreds of Guillows etc conversions:

http://www.rcgroups.com/forums/showthread.php?t=827861

[matiac]

I have an old Guillow's Piper Cherokee I wanted to convert to maybe 3 channel, have the frame(s) for everything together, just have to put everything together and cover it. It was one of my Dad's lost "projects"...it'd be pretty kool to see it fly...

[JetPlaneFlyer]

Converting Guillows models is doubly hard.. First something like the Cherokee at 20" span is pretty small so very weight critical. Second is the fact that most Guillows planes are over-designed and use ridiculously heavy and hard balsa wood, so even if built 'freeflight' they are usually too heavy to fly. By the time you add RC gear they are even heavier (usually much heavier because people use too heavy kit and beef up an airframe that's already too beefy).

Not saying that it cant be done, because it can and it has been, but it's not easy.

[matiac]

That said, I gotta tell ya, just the bare frame work is pretty beefed up, but still pretty light. My Dad probably got this model when I was in my mid teens...it's pretty old, been sitting in my Parent's cellar for years, and right before my Mom passed she told me to take it if I wanted it, first balsa model I ever built, I have a picture of the finished frame somewhere...here it is:

[earthsciteach]

Wow. Quite a story, matiac. That is a beefy airframe. Keep us posted!

[matiac]

I've been trying to find some thin balsa ply to skin it with, and if I can keep the overall weight down, I was thinking of doing a setup like the EFlite Albatross, i.e., a receiver brick, and just have elevator/rudder, and a small gearbox setup like the 'tross has, or maybe that setup with a bigger motor, I dunno, or maybe just a nice static model to go with the others...

[JetPlaneFlyer]

Originally Posted by matiac

I've been trying to find some thin balsa ply to skin it with, and if I can keep the overall weight down, I was thinking of doing a setup like the EFlite Albatross, i.e., a receiver brick, and just have elevator/rudder, and a small gearbox setup like the 'tross has, or maybe that setup with a bigger motor, I dunno, or maybe just a nice static model to go with the others...

What I'd suggest is you build the model for static display. If you are building it to remember your dad then you don't want to risk breaking it anyway, plus the fact is it already looks too heavy.

The idea of using the gear out of a PZ ultra micro is great but to do so you need to aim for am all up weight right in line with an Ultra micro foamy, and to do that you need a super light balsa airframe.

[matiac]

Yeah I know, still though, it woulda been pretty neat to see it fly...