1.8m glider find

[Tonero311]

So I'm looking as much info about this motor glider and Tx system I just managed to pick up at a local charity. Considering ripping out all the electrics and updating with modern equivalents. All info or suggestions much appreciated.
Bought for me by my Dad as a birthday present. He's defo in 1st place for best present this year😀.

 

[Tonero311]

So far I have found, this is an Irvine Early Bird motor glider. Standard weight with original brushed motor and NiCad battery setup is 1475g. I'm sure I can improve that with a bit of an update to the electrics and with a sprinkle of carbon fibre here and there. Plus I dunno what to think with this being a 3 channel RET setup. I kind of link the bank control with ailerons. Wonder how hard it would be to remake a straight wing with carbon fibre spar?
The transmitter is a JR Propo/Macgregor 35 MHz 5 channel with dual rate functions. Bit old for me. Is there any worth to these old systems or anybody that would use them? Thinking about passing this one on as I can't see any use for it within my fleet. Oh yeah, weighs a ton too😂.

 

[rockyboy]

I think it would be worth the time to switch to a brushless and LiPO setup - will save weight and I think with the battery moving forward will still balance out OK.

On the 35MHz radio, I know the European Electronic Commission made an exception for model aircraft to use this frequency, but I believe that requires a HAM technician or higher license to legally use in the USA. We had 72 MHz reserved for air RC and 27 MHz for ground in the olden days. Not sure about elsewhere in the world - recommend checking your local regulations.

 

[Tonero311]

I think it would be worth the time to switch to a brushless and LiPO setup - will save weight and I think with the battery moving forward will still balance out OK.

On the 35MHz radio, I know the European Electronic Commission made an exception for model aircraft to use this frequency, but I believe that requires a HAM technician or higher license to legally use in the USA. We had 72 MHz reserved for air RC and 27 MHz for ground in the olden days. Not sure about elsewhere in the world - recommend checking your local regulations.

I'm in the UK here. Though I do believe your right about the 27mhz being for ground vehicles, 35mhz for aircraft and another above that you need a HAM license for, from what I have read so far that applies over here too.
The transmitter I'm going to see if I can sell it on and fund a few upgrades to the air frame. It had 2 JR NES-507 servos in it I'm going to switch out too. They are huge and heavy so they are going. Took the battery (1700mah 6s NiCad) and the Rx, they weighed 355g alone😯. I'm intrigued as to what the massive big honking brushed motor is going to weigh.
Noticed I need to make a small repair to the rudder too. Tape hinge has given up slightly at the bottom with pressure overtime from the control horn being set at its outer most position. The covering in general is looking quite rough there so may just recover the tail feathers again.
The wing is bugging me too. It's a 1.8m with polyhedral, but I would really like ailerons and possibly flaps too. I've only had 1 3 channel RET plane and I didn't get along with that style of control too well. So the thought is already going through my mind to modify the wing somehow and get a carbon fibre wing spar in there.

 

[rockyboy]

That sounds like a good plan to me!

 

[Tonero311]

https://www.rcgroups.com/forums/showthread.php?2053982-Early-Bird-100-Vintage-1970-s-Glider-Kit
According to this old for sale ad. What I've stumbled upon is a rare 1970s kit. That makes this birdy older than me😯wow😀! This is making think a bit harder about modifications to the air frame now.

 

[Jackson T]

This will be interesting!

The wing is bugging me too. It's a 1.8m with polyhedral, but I would really like ailerons and possibly flaps too. I've only had 1 3 channel RET plane and I didn't get along with that style of control too well.

I recently finished building a large balsa motor glider with only RET control. There are definitely some shortfalls, but I haven't flown a glider with ailerons yet. What are the biggest differences that I might be missing out on?

 

[rockyboy]

This will be interesting!

I recently finished building a large balsa motor glider with only RET control. There are definitely some shortfalls, but I haven't flown a glider with ailerons yet. What are the biggest differences that I might be missing out on?

Able to land in a cross wind without clenching and steering with your shoulders!

 

[quorneng]

Tonero311
My suggestion would be to completely change to a brushless motor and LiPo along with modern rx and small servos but otherwise leave the structure alone.
The weight you will save will be dramatic (about 50% of the original set up) so seriously reducing the load on the old structure.
The reduced weight will result in a dramatic improvement in climb performance even if the brushless motor only matched the power of the original brushed one. It will be tiny in comparison. A 1500 mAh 3s LiPo will give you more power and duration yet be only half the weight of the 1800mAh NiCd battery.
The original polyhedral wing was designed for RET and will actually not work that well with ailerons unless you completely rebuild the wing with limited plain dihedral.
Remember in its original form it was a stable glider not a sports plane and properly set up it will only need gentle 'nudging about the sky'. Fly it with the object of seeing how long you can keep it up using as little power as possible.
I think the result might surprise you.

To give you an idea my original brushed, 1000 mAh 8 cell NiMH, RTF foamy had a maximum duration of about 5 minutes. Converted to brushless and 1500 mAh 3s LiPo but using the same size prop it was overall 15% lighter, had plenty of power to spare and a cruise duration approaching 20 minutes. It was like chalk and cheese.

 

[rockyboy]

It was like chalk and cheese.

 

[Flying Monkey fab]

Considering ripping out all the electrics and updating with modern equivalents.

that's what I'd do.

 

[Tonero311]

Tonero311
My suggestion would be to completely change to a brushless motor and LiPo along with modern rx and small servos but otherwise leave the structure alone.
The weight you will save will be dramatic (about 50% of the original set up) so seriously reducing the load on the old structure.
The reduced weight will result in a dramatic improvement in climb performance even if the brushless motor only matched the power of the original brushed one. It will be tiny in comparison. A 1500 mAh 3s LiPo will give you more power and duration yet be only half the weight of the 1800mAh NiCd battery.
The original polyhedral wing was designed for RET and will actually not work that well with ailerons unless you completely rebuild the wing with limited plain dihedral.
Remember in its original form it was a stable glider not a sports plane and properly set up it will only need gentle 'nudging about the sky'. Fly it with the object of seeing how long you can keep it up using as little power as possible.
I think the result might surprise you.

To give you an idea my original brushed, 1000 mAh 8 cell NiMH, RTF foamy had a maximum duration of about 5 minutes. Converted to brushless and 1500 mAh 3s LiPo but using the same size prop it was overall 15% lighter, had plenty of power to spare and a cruise duration approaching 20 minutes. It was like chalk and cheese.

Cheers for reply @quorneng. With careful thought, sleeping on it and finding out the vintage of this plane I've come to the same conclusions as you. Update electrics and leave everything alone as much ad possible. I think it would be a real sin to do anything drastic to the air frame. Have any tips on motor selection by chance?
With this style of aircraft I am a genuine green horn like. First balsa and covering plane, first glider and first motor glider to boot. Really don't want to mess this up, plus my Dad really wants to see this one fly too.

 

[Tonero311]

This will be interesting!

I recently finished building a large balsa motor glider with only RET control. There are definitely some shortfalls, but I haven't flown a glider with ailerons yet. What are the biggest differences that I might be missing out on?

It was the original Pietenpol mini 3ch I had that I didn't like that setup. I kept over correcting and stalling with RET on that one. As soon as I rebuilt with ailerons in it and straightened the wing, it handled beautifully. To be fair this was the 1st plane I built/flew as well.
With more experience under my belt now I'm hoping to get the hang of that setup. Like @quorneng said, just nudge it about the in air. Treat it like a graceful dancer and not a powerful acrobat.

Able to land in a cross wind without clenching and steering with your shoulders!

That's an excellent point there😂🤣. Think the first landing I ever do on this bird is going to be a clencher alright.

 

[bracesport]

@Tonero311 - that radio looks like a classic - I would frame it given the price of new gear being so good these days - have you turned it on to see if anyone is home?

Oh, the glider looks pretty cool too!

 

[Tonero311]

Hey @bracesport. I like that idea now. Frame it for Nostalgic purposes. Got the original Rx, Crystal's and servos here to go with it too. Would make a lovely display for a collector(me for now you've given me this idea). Going to have to look into giving it a proper clean and restoration then.
Haven't turned it on. The old NiCad battery pack is long dead I would say. Not sure if i have the right connections on my charger to risk trying to put some juice in.

 

[bracesport]

@Tonero311 - my old FM JR is way newer but sat in a box for 15yrs - works like a dream!

 

[quorneng]

Tonero311
Can you see any numbers on the original motor like 380. 480 or 540? Even just its weight would give a clue to its power.
I suspect you will be able to use something a small as the 39g Emax CF2822 1200kV as it will still be more powerful than even a 160g 540 brushed motor. It will likely to be able to turn the same size (9"?) prop as well.

Apart from curiosity I wouldn't even bother trying to charge the original NiCd as after a long period of non use the required chemical reactions for charge & discharge will have irreversibly decayed.

There is actually nothing wrong with 35 meg gear, particularly now as it is so little used by every body else! I still use it (30 years old) on several of my planes.
You need no HAM licence in the UK for the radio control but to legally fly it, or any other plane over 250g, after 30 November 2019 you are required to obtain an unmanned aircraft operators registration number.

 

[Tonero311]

Tonero311
Can you see any numbers on the original motor like 380. 480 or 540? Even just its weight would give a clue to its power.
I suspect you will be able to use something a small as the 39g Emax CF2822 1200kV as it will still be more powerful than even a 160g 540 brushed motor. It will likely to be able to turn the same size (9"?) prop as well.

Apart from curiosity I wouldn't even bother trying to charge the original NiCd as after a long period of non use the required chemical reactions for charge & discharge will have irreversibly decayed.

There is actually nothing wrong with 35 meg gear, particularly now as it is so little used by every body else! I still use it (30 years old) on several of my planes.
You need no HAM licence in the UK for the radio control but to legally fly it, or any other plane over 250g, after 30 November 2019 you are required to obtain an unmanned aircraft operators registration number.

From info I have gathered it's a 600 size brushed motor. Need to check out the folding prop and spinner for any identifying numbers. I would use a motor that's a little better than the CF2822. Have one of those and retired it permanently due to the weak mounting plate. Motor was wobbling after every flight. Something similar size and power but a bit more solid in its construction.

 

[quorneng]

The motor was only a suggestion to indicate the likely reduction in weight but I doubt even a 600 brushless (200g and 90W?) is any more powerful than a 2822 size brushless although it can probably turn a slightly bigger diameter prop.
The prop should have numbers on the front face of each blade giving you the diameter and pitch.
It would pay to measure the shaft diameter of the 600. If it is 3 mm or more likely 3.17 mm (1/8") then it is possible to get a brushless motor with the same size shaft so the prop and spinner could be a direct swap as long as it is not too big for the motor and over loads it.

Don't quite agree about the 28** drum mount though. My first, actually a 2812, is now well over 6 years old, flown regularly with never a mount problem. The pair of grub screws do have to be really tight so each actually makes a small indentation into the motor's aluminium boss.

 

[Tonero311]

The motor was only a suggestion to indicate the likely reduction in weight but I doubt even a 600 brushless (200g and 90W?) is any more powerful than a 2822 size brushless although it can probably turn a slightly bigger diameter prop.
The prop should have numbers on the front face of each blade giving you the diameter and pitch.
It would pay to measure the shaft diameter of the 600. If it is 3 mm or more likely 3.17 mm (1/8") then it is possible to get a brushless motor with the same size shaft so the prop and spinner could be a direct swap as long as it is not too big for the motor and over loads it.

Don't quite agree about the 28** drum mount though. My first, actually a 2812, is now well over 6 years old, flown regularly with never a mount problem. The pair of grub screws do have to be really tight so each actually makes a small indentation into the motor's aluminium boss.

To be fair. It was probably down to my own misuse/abuse of it as a beginner. It took a fair few nose dive dirt naps and the grub screws pretty much rung after the 4th or 5th crash. They probably hold up very well in the hands of someone who can land it with some skill at least some of the time🤣(that has yet to be tested and perfected on a different model that's coming up to completion with me).
Cheers for the suggestion though and in hindsight it would be easier to mount to the existing firewall once reinforced a little.