Guillows DHC Beaver, rubber powered flyer ....hopefully!

[kartman24]

I am currently building the Guillows Beaver, i was going to convert it to light weight R/C but then had a change of heart and thought, what the hell i haven`t built a rubber powered plane for 40 odd years, it might be fun to take a step back in time! I built several Guillows back then, i certainly remember the Trojan and i also built my fair share of Keilkraft gliders and rubber powered. My how things have changed, laser cutting and Eze dope to name but two, i am re learning the best way to put these together to make them look nice, back then it was lashings of balsa cement, straight onto the joint with no pre cementing ends before the final glue and a thick layer of dope. They still flew though i am hoping for more in the way of flight times this time around! A quick question on the Beaver, the plastic cowl seems to have a lot of `give` in the centre where the prop bearing sits, is this going to be strong enough when you have numerous winds on the rubber motor or do people glue a balsa or thin ply disc to the rear face of it?
Many thanks for any replies or advice to a second time around `newbie`
.................Martin

[kartman24]

Okay, a couple more questions, what are you all using to glue the plastic cowls onto the balsa backplate, i was thinking of using UHU Hart which i have here or maybe a smear of Epoxy, i have roughened the inside of the plastic cowl to help the glue key to it.
Also i am going to be using the rubber supplied with the kit as it will be flown just for a bit of fun , do you lube the rubber, if so with what?............Martin

[Balsa Pilot]

Hey Martin, Good morning!
Here's a suggestion or two for you:
Rubber lube is available in many forms- some use ArmorAll in a baggie and scramble the motor in that(tie it first though),
others use SIG RubberLube-available at your LHS, then there's the tincture of glycerin/green soap squad, and there are others I've heard of but am not familiar with. Personally, I use SIG RubberLube right out of the jar. You can consult the little info/build book supplied by Guillow's right in the kit, they mention at least two methods I believe. With the DHC-2 Beaver I found the kit rubber to be a bit harsh, and instead found two loops of 1/8th sport gave a more moderate and longer run.
As a caveat: I'm only two and a bit years in, and am learning about this as I go, also, rubber combinations/propellers/lube/blast tube/ winds/winders/torque meters etc is a whole "science-black art voodoo" kind if thing, and if you can get some of the guys below to tune-in they will probably help much more than I can. But whatever you do, finish it, fly it, and have fun, there is nothing better than seeing an airplane you built climb away from your hand and claw for altitude!!
As a suggestion two of the Guru types on this site are "Mitch", and "Steve Blanchard"- they have numerous posts that are very helpful especially with this kind of stuff.

Hope this is at least semi-helpful,

Henry

[kittyfritters]

... the plastic cowl seems to have a lot of `give` in the centre where the prop bearing sits, is this going to be strong enough when you have numerous winds on the rubber motor or do people glue a balsa or thin ply disc to the rear face of it?

Yes, I would reinforce the plastic cowl. You should put a disk of balsa or thin ply behind the front face of the cowl and put a few "struts" ( 4 is a good number) between that disk and the front of the Former 0 that goes into the back of the cowl.

23871.jpg

Also, it's a good idea to make the "key" in the back of the cowl more robust by adding some side pieces and making those and the pieces at the top and bottom a bit deeper into the fuselage than the keys supplied, extending past Former 1 by 1/4 to 3/8 inch.

Otherwise, the Beaver, in spite of the short nose moment, flies quite well under rubber power.
https://www.youtube.com/watch?v=iRn_6eW1en8
And another example
https://www.youtube.com/watch?v=rdXRtjpVRyM

I would start with a motor of two loops of 1/8" flat, F.A.I. tan sport, about 1-1/2 times the hook to peg length. I lube with either Armor-All Classic or an automotive silicone lubricant and rubber protector spray.

Hope this helps!

Howard

[Steve Blanchard]

With Howard being the designer of the model I will have to say definitely he knows what's up. The biggest thing to always remember with Guillow's models is that there needs to be a way to make the thrust line adjustable and it needs to be very stable. If the thrust angle changes during the power phase of the flight the flight is going to be squirrelly at best. Most likely it will be a non flight. There are a few ways to make the the front end of these models better for stability and be able to receive the necessary thrust adjustments. Here is a look at the inside of the front end of my 400 series spitfire.

[Steve Blanchard]

And the outside view: