Finding the center of gravity on my new profile Bipe..

[Cdr. Instigator]

Well, I finished putting together a foam board 30" Ultimate from Foamyfacctory..

http://foamyfactory.com/plans/ultimateplans.zip


I put it all together without the electronics. It came out to 7.55oz. without glue. I figure after everything is installed it will be around 18oz. AUW.

Well, I have it all built now. I used hot glue through out the build. AUW came out to 1lb. 2.80oz. or as I guessed 18.80oz.

I tested all the electronics. I taxied it up and down.. all control imputs are ready working as planned..


The only thing I used from the plans is the model. I didn't use the location it called for the rudder and elevator servos. I used 2 servos for my eilerons instead of one. I used foam board with paper on..instead of EPP or Depron. So, yes it's quite on the heavy side. but, it's ok for me since I'm not planning on doing too much 3D stuff.. mostly pattern park flier style.
So I broke a lot of the build instructions..

So, now that I have this built and it's ready for a maiden.. I'm concerned about the center of gravity..

How would I locate it on my bi-plane..

It's 30" wingspan..

Pictures are below..

[JetPlaneFlyer]

On an ultimate the CG should be about 50% of the top wing chord at the centre point of the wing. But if you read the plan you will find it's already shown. Providing you maintained the plan geometry then the CG will be unchanged from the plan regardless of what materials you used or the model weight.


Steve

[Cdr. Instigator]

So, the original center of gravity shouldn't change even though.. I didn't stack the servos for the rudder and elevator and I ended using 2 servos for my ailerons instead of just one?


If 50% of the top wing cord is right.. then that is exactly where my center of gravity came out to. I just wasn't sure if it was measured on the top or bottom wing..

50% of top wing is sect..

Thanx..

[JetPlaneFlyer]

The 'desired' position of the centre of gravity, as marked on the plan, is an aerodynamic requirement and is not effected by where you put the servos, batteries, or anything else..

Where you put the servos and other hardware may mean that you have to add lead to achieve the desired CG position, so it makes sence to locate the hardware such that the model ballances at the desired CG location without having to add any weight.. if possible.

Sounds like yours has come out ok anyway. Happy flying

Steve

[Cdr. Instigator]

Ok, now that we got the center of gravity question answered...

2nd question..

Can someone recommend how and what to build the landing gear from?

I had made the landing gear out of thick ? gauge piano wire, but it was too flimsy.

I want to use aluminum.. or is it a lot cheaper just to buy some made from fiber from my local hobby shop?

[Cdr. Instigator]

Ok, finished my Ultimate from foamyfactory..

AUW came to 19oz. powered by an E-flight 370 out runner on 3S.

Ready for maiden.. taxied around and all systems are go.


I ended up making my own landing gear from flat aluminum stock I got at M&M Hobby Center. I first made a pattern for the landing gear using some manila folder scrap. I figured out the length I wanted and the distance to all bends.

Payed a visit to a some friends where I used to work at, where they have some machining equipment. I used their band saw and drill press to cut the pattern. Bend it and installed the 1.75 wheels. Look at how it all came out..

[pd1]

The airplane looks very nice.
Now to fly it.

Paul

[Cdr. Instigator]

Today was a real nice day for a maiden. Winds were very calmed and it seems like my only opportunity to take my never before flown Bipe.

Never having flown a bipe before, I was a little nervous as I didn't know it's flight characteristics. With cautious optimism, I went to my local Wally World where it's back parking lot is almost all ways empty. Took my bipe out of my Convertible Firebird, turned on my radio and plugged in the Bipe's 3 Cell 1550mAh battery. Did my pre-check on all the control surfaces. Did a round of taxing and position the Bipe plane with the 4 mph winds to it's nose. The moment I had been waiting for was finally here... There was no turning back as soon as I committed myself to go for it.

Powered up slowly and started rolling straight and true. Half throttle on the stick and about 20 feet it started to rotate and became airborn with nothing more than throttle applied. Kept it in a straight trajectory to avoid the 40 feet night lamp post scattered around the parking lot. Once I was above them I started my first left turn. The turn was done at half throttle and it was smooth and very predictable. Did I fly-by right in front of me and it beautiful... It's flight characteristics was as though I was flying a trainer. I was very surprised in it's handling.. nothing could have prepared me to how beautiful it flies. I was expecting an out of balanced, over weight rock with a prop. But, I have to say, that this was by far the best flying, easy to maneuver trainer like Bipe. I had no idea that this bipe would also be so.. so easy to land.

After about a 12 minute flight with a loop and roll.. tumble or two I proceeded to bring it in for a battery check and change. made my approach from the left and began my decent. I nailed a perfect 3 point landing with no damage to it's alluminium landing gear I made from scratch. Brought it in and put 3 more batteries through it. In the process of my bipe's maiden flight, I got an offer to build one for a man that stopped to check my plane out. and a kid in a bike admired it and was amazed at what you could do with dollar tree foam board. maybe, he will get the bug and start to read up on RC Flight.

Very successful maiden flight... Can't wait to take her up for another set of flights..

[pd1]

Congratulations.

Paul