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Converting a Fubar to electric RC model help. - 12/19/2012 2:50 AM   
John Baligrodzki



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From: North St.Paul, MN, USA
Status: offline 		Have found a set of plans for a Midwest Fubar free flight model. Always liked this model. When I was about 5 and some of neighborhood dads would build and fly them. Plan to build one with rudder, elevator and throttle control. Hoping to get a bit of help here.

This ship has the polyhedral wing mounted on a pylon at +3 degrees incidence. Stab is set at zero degrees and has a airfoil shape. My first question is: Should the wing have the three degrees of positive incidence? I know nothing about free flight but as I understand you want the plane climb under power. Thinking the positive incidence makes that happen.

The CG is shown at .75" forward of the TRAILING edge. Is that so far back since the stab is a lifting stab? Or because of just how a free flight ships need to be to fly properly?

Hoping someone here has either converted a few free flights to electric RC or perhaps has some answers or suggestions.

Thanks!

John B.

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RE: Converting a Fubar to electric RC model help. - 12/19/2012 1:07 PM   
Strat2003


 

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Status: offline 		My experience with old time free flight models converted to R/C is this:
If you set it up like a free flight it will fly like one. Expect a strong climb with throttle and a nice glide with the motor off. You can do some cruising around at part throttle, but if you want to fly it like a sport R/C plane you need to adjust incidence/balance point/thrust angles to something closer to what's used in R/C.

Scott

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RE: Converting a Fubar to electric RC model help. - 12/20/2012 12:08 AM   
John Baligrodzki



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Status: offline 		Scott,

Thank you for the info. Yes I want the plane to fly as an RC model. So thinking to take out the incidence. Of corse I would set it up so I could adjust it if needed. CG is another matter. No idea what to here. Thinking it should be further forward. Anyone have any ideas?

John

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RE: Converting a Fubar to electric RC model help. - 12/20/2012 8:41 PM   
Strat2003


 

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Status: offline 		My SAM Limited Engine Run Playboys and Bombers are set up with incidence and balance points (50% to 55%) as indicated on the plans. They have large lifting stabs. In flight they require full down trim under power (it's a lot of power) and then neutral to full up trim in the glide. This makes me think that you would keep the balance point somewhere in the 'stock' location even if you reduced the incidence.
Just a guess, though.

Scott

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RE: Converting a Fubar to electric RC model help. - 12/21/2012 2:00 AM   
John Baligrodzki



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Status: offline 		Scott,

Was talking to a friend about this conversion today. He said someone he knew converted a free flight to RC. At takeoff the plane literally went straight up and required full down elevator to save the plane then after that required quite a bit of down elevator when power was applied. Did not ask anything about what plane it was or how it was set up. Bet it had positive incidence and a lifting stab.

Thinking at this point to take out the positive incidence. Of course be at least a few weeks to frame this ship up, then figure out the CG.

Thanks,

John

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RE: Converting a Fubar to electric RC model help. - 12/23/2012 12:51 PM   
JohnBuckner



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Status: online 		John I hope I am not too late. First read your thread just before going into the hospital for some major stuff and sorry I could not reply earilier.


First every single one who tries a conversion of this type earlier Free flight to radio assist starts screwing with decaledge. Wing to horizontal and so on. This is a mistake, and everyone starts trying to move the CG forward. What is completely ignored in these cases is the lifting stab is blamed and the real reason these ships used an aft CG is the deeply underchambered airfoil virtually all these airplanes used has a pitching moment exactly opposite of airfoils used in more common RC models.

In most instances I have witnessed of the fellows trying to change everything they are rewarded with a very poor flying airplane that does not acheve that wonderful floating glide or climb with authority.


As incicated by Scott you are far better off going with original CG's provided you can locate those numbers and not changing the decaledge at all.

your airplane under RC will not be flown like a modern sport airplane at all. In effect you will fly it with two throttle position full throttle and full idle.

The typical flight with my eighty inch playboy OS .35AX goes like this: I do an easy handlaunch at around quarter throttle (no more). Then I will typically roll in full throttle and pitch the airplane to full vertical. I just let the ship go straight up to whatever I want and at that point I pull power back to full idle and push the airplane over to level glide. From here the engine never agine needs to leave the idel position and the three ounce hayes provide 36 minutes of idel time. This airplane balances at around 60%.

John


Here is a link to the typical launch and flight I described above: This is also the same method I use for my Kerswap both on floats or wheels It balances about 55%.

http://www.youtube.com/watch?v=6C6owixY3GE&list=UUAbCtRJL2h_0PWTkXPcXnWA&index=22

My current project is a Zombie getting ready for cover. I am doing it for a friend and it will use an OS .25AX. CG will be around 75%.


< Message edited by JohnBuckner -- 12/23/2012 1:47 PM >

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RE: Converting a Fubar to electric RC model help. - 12/23/2012 4:47 PM   
John Baligrodzki



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Status: offline 		John,

Thank you for the valuable information. As of today just framing up the wings. As I figured free flight planes are not really designed for RC. The original plan has CG and all details. Will build the plane as the plans show. Of course once it has been flown will be easy to make minor changes to the CG and or wing positive incidence.

I will post some pictures once I get more built.

Regards,

John B.

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RE: Converting a Fubar to electric RC model help. - 12/23/2012 7:42 PM   
JohnBuckner



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Status: online 		excellent John by not drifting to far from original angles, CGs you will be rewarded by the airplane you had dreamed of.

Here are photoo of my lastest project of this type a Zombie that I am doing for a friend later this summer and some stray shots of my Kerswap:

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RE: Converting a Fubar to electric RC model help. - 1/10/2013 2:20 AM   
John Baligrodzki



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Status: offline 		Here are a couple of pics of my framed up Fubar. So far so good. Only need to build the stab anhedral tips. Then figure out where to put servos, battery, receiver and speed controller. going touse a 280 motor.

Regards,

John B.

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RE: Converting a Fubar to electric RC model help. - 1/10/2013 12:58 PM   
JohnBuckner



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Status: online 		Outstanding John she is simply beautiful and reminds me of a ship back in the fifties building at least two and flew free flight. It was a Midwest offering called the Half A Blazer.

May I suggest an excellent servo to use for your ship is the Hitec HS85 Not the metal gear version. Its a favorite of mine for many lite aircraft applications and will work well for your ship throttle, elevator and rudder. Its what I am using on my Playboy, Kerswap and what I installing in the Zombie I am building up for my buddy.

Which brings up the thought I think I am stiring up four fellows from here with five airplane that should be elgible to participate in the Sams championships in October near Las Vegas. Consider taking a vacation, bring the Fubar and joining us. We are all newbies to Sams but looking forward to having a ball.

John

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RE: Converting a Fubar to electric RC model help. - 1/10/2013 2:28 PM   
jjscott



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Status: online 		Nice work on the Fubar. I built the Midwest kit as a kid; must have been in the late 1950s. It was powered with a Space Bug Jr converted to an eyedropper tank. It gave me many great flights until I lost it one day. I did get it back about a year later. Apparently it was stuck up in a tree and finally dropped to the ground where it was found. The airframe was a soggy crumpled mess, but the engine was fine.

Thanks for the thread. I've got a set of Fubar plans and am considering one, again with a Cox for nostalgia reasons.

Jim

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RE: Converting a Fubar to electric RC model help. - 1/13/2013 1:53 AM   
John Baligrodzki



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From: North St.Paul, MN, USA
Status: offline 		Thank you for your nice comments.

Now ready to mount the E-Flite 280 Outrunner, place the battery, speed controller and servos. Pictures show the intended positions. The CG on the plan is pretty much at the former in front of where the servos are located. My gut feeling is that even with the CG back so far I am still going to need to locate all the electronics as far forward as possible. My reasoning for this is an 049 is probably heavier than the 280 motor. Plus the battery and servos are even further back.

Also I will assume that I will want to have an opening in the bottom to allow some air to keep the speed controller and battey cool. Though unless iIam really pushing it I can't imagine things getting too hot?

Appreciate everyones 2 cents worth.

John

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RE: Converting a Fubar to electric RC model help. - 1/22/2013 2:18 AM   
John Baligrodzki



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From: North St.Paul, MN, USA
Status: offline 		Been getting some more done and here are a couple of pictures. This past weekend just could not resist getting the wing and stab covered and finished up. funny in all my years of building model airplanes this is the first time I have used transparent covering. Used the Coverite lightweight material. Was going to buy a non trans parent roll for the fuse but cheaped out as it comes on 6' long rolls and only need about a foot or so for the fuse. Only real option is to cover the fuse with the trans yellow, though would really like it to be blue or green.

I have some silkspan that might work though that would require getting out the dope and with it being 15 below here in Minnesota can't work outside or in the garage. Anyone have any ideas?

Also concerned were the CG will be based on my current plan for placement of the battery controller aned receiver. Of course not too many options as there is only so much room in the fusealage.

Looking forward to finishing this ship up in the next week or so.

Regards,

John B.

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RE: Converting a Fubar to electric RC model help. - 2/11/2013 12:39 AM   
John Baligrodzki



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Status: offline 		Finished covering my Fubar today! Now just need to install speed controller and receiver. With the 300MA battery as far forward as possible she balances 3/4 in front of the trrailing edge as the plans show.

The first picture shows a free flight ship my dad built around 1965. He based it on the Fubar. He liked the Bonaza light plane so he gave it a V tail. Yes even with a sheet balsa wing this plane flew very well.

Used the Coverite lightweight film material. Worked well. The trans yellow is really more amber but it will work.

As soon as I get a reasonable day here in Minnesota will get this plane flown.

John B.

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RE: Converting a Fubar to electric RC model help. - 2/11/2013 12:58 PM   
Strat2003


 

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Status: offline 		That looks very nice!

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