Finally got it pretty much sorted. 😀 Lidl glider RC conversion biplane, 3rd test flight was much more successful. Quite stable and relaxed easy flying. Just needs a little more elevator trimming as I was having to keep the nose up while flying. Needs a bit more trimming. I think main problem was CoG was way too far back. Shows the importance of getting CoG right!

Build blog is link on the video.

Test Flight no Three of My Lidl RC glider Biplane Conversion - Finally Got it Right! (6 min 48 sec)

Congrats! Flies much better!

Originally Posted by Aeronut41

Congrats! Flies much better!

Thanks mate. Pretty much sorted and I think it looks good in the air. I'm pleased with it and a bit of a learning process sorting it out!

that is a very pretty airplane, nice flyer!

Originally Posted by bisco

that is a very pretty airplane, nice flyer!

Thanks mate. I am very pleased with it. Good old Lidl's, great and cheap for experimentation!

did you design it, or are there plans somewhere? i'd love to build a bipe when my skilss get to that level.

Originally Posted by bisco

did you design it, or are there plans somewhere? i'd love to build a bipe when my skilss get to that level.

Hi mate,

Designed and built from Lidl foam gliders. £9 each from Lidl supermarket. The biplane needs two foam gliders to get the two wings!
The build blog is here. And 1st test flight which wasn't as good as the 3rd as it was too tail heavy.

LIDL GLIDER BIPLANE BUILD BLOG + MAIDEN! - Lidl Glider RC Conversion (15 min 20 sec)

These Lidl gliders are in Lidl supermarkets (in Europe) once a year around May/June for about a week. I saw one a couple of years back and bought it, about £9 maybe, thinking maybe I could convert it to RC. Then I went online and found they have a big following! Go online and search Lidl glider RC conversion.

Not a lot of skill level compared to making good balsa models, mostly stuck together with a glue gun that cost me just a few quid! Getting the thing balanced right was more tricky though than a single wing plane.

As I say you can only get Lidl gliders once a year, and when they are in the shops people buy a few at a time. I confess last time I bought 4.

BUT Wish sell a glider year round that is excactly the same form, shape size etc. foam and about £6 to buy. They can arrive a bit bent up but you can straighten with boiling water. Two of my six conversions, including my twin engined one were Wish gliders.

I'll put a link at the bottom.

That biplane is my no 6 conversion. They are nearly all on my channel. I guess most people convert to power or powered glider.

My first build is here. It's yery rough compared to my later builds as I didn't really know how to start. Plus a bit heavy as I put quite a bit of carbon in and a big motor. Flies well. That video shows well how to convert a Lidl.

Lidl Glider Power Radio Control Conversion - Full How to do it Video (13 min 2 sec)

I've also made a twin engined one. Here. Build blog is here. Flies really well.

Twin-Engined Lidl Glider Detailed Build Blog - This is how to do it! (25 min 11 sec)

A twin boom one, that took two gliders. Very twitchy to fly. All the test flights are on my channel!

Twin Boom Lidl Glider RC Conversion Build Blog : Part One My 4th Lidl RC Conversion! (6 min 58 sec)

Video here shows how to straighten the foam wing.

The Best Way to Straighten, Remove Dihedral from a Foam Wing or Lidl Glider Wing for RC Conversion (5 min 17 sec)

Twin maiden

Looks great in the air. (The biplane was the trickiest build but flies well now I've got the CoG right.)

Twin Engine RC Lidl Glider Super Test Flight - Warts and all, but flew brilliantly in the end! (7 min 45 sec)

Anyway if you want some cheap fun and want to try building a Lidl or a Wish is a good place to start. There are also a couple of internet groups that I can't mention on here apparently. Search Lidl Glider Group..exchange Ideas For Radio Install

Wish glider
https://www.wish.com/product/5adc9f2...1d06?share=web

edit, sorry I see they are showing sold out, but they do usually have them in stock.

thank you bob, looks like i have some fun reading ahead of me!

Originally Posted by bisco

thank you bob, looks like i have some fun reading ahead of me!

You're welcome mate! Hello from the UK, it's 0300 here, time I was in bed!

That's a tribute to that plane's toughness. I have lost some planes to the tail heavy thing.

What's the old adage? A nose heavy plane flies poorly , a tail-heavy plane flies once.

It looks a bit like the upper wing incidence might be a bit too high, but that could be a camera angle thing.

For bipes, you want the upper wing to have slightly lower incidence than the bottom so that the bottom wing stalls first, if the upper wing stalls first you have a low wing plane that is top heavy and you get smasheroooo.

Having said that, I have a bipe where the 2 wings are parallel and flies OK.

Anyways, that's a very efficient smooth flier. Nice!

Originally Posted by rotagen

That's a tribute to that plane's toughness. I have lost some planes to the tail heavy thing.

What's the old adage? A nose heavy plane flies poorly , a tail-heavy plane flies once.

It looks a bit like the upper wing incidence might be a bit too high, but that could be a camera angle thing.

For bipes, you want the upper wing to have slightly lower incidence than the bottom so that the bottom wing stalls first, if the upper wing stalls first you have a low wing plane that is top heavy and you get smasheroooo.

Having said that, I have a bipe where the 2 wings are parallel and flies OK.

Anyways, that's a very efficient smooth flier. Nice!

Thanks for the comments. Re the angle of the upper wing, I did quite a lot of research on biplane wing angles, overlaps and found a lot of contradictory information! Andrew Newton on YouTube had done some angle tests and I went by his results? I went with 3 degs positive ( from his results ) for the upper and read that the upper should stall first? I guess that makes sense with mine anyway as the ailerons are on the lower and if the lower stalled first I'd have no flight control!

I did give the tail plane a bit more positive angle relative to the lower wing in my changes after the first couple of test flights as it had a tendency to dive.

I have a foam Flight Test foamboard SE5 which I built that flies really well, but someone obviously figured the angle of decalage (as it's called) and the overlap for that design. I discovered very quickly after trying to build this from two cheap foamies that biplanes are complicated planes! It flies anyway, probably a bit of luck in that too!

Been there done that. In reality if your 2 wings are close enough in incidence angle (decalage) yoiu'll be good to go, but believe me if you have a big difference in wing angles you want the bottom wing to stall first. My first biplane build I never heard of wing incidence at the time and of course I made the top wing pointing too far upwards and I kept messing with cg thiking that was the problem...long story short it had one too many terrible stalls and I threw it away.

Another one of my mistakes you can learn from, I was reading a lot of stuff on gliders and ran into a website that said Negative wing incidence relative to the horizontal stab is a good thing for an efficient plane. NOT.... Made a bf109 that way.... it flew great until I turned...then all hell broke loose... an aero guy could tell me why probably...again I kept moving cg forward to no effect.

Now I do most of my planes at 1.5% upward wing incidence relative to stab since my best flying warbird was made to that spec. BUT... I recently made a parasol wing before reading that you want zero incidence on those...I THINK?... anyways I gave it a pretty big wing incidence and I had to make the elevator real draggy to compensate.

Another thing I found it really does work if you simply assume the thing is a monoplane when entering the numbers into a cg calculator. That is, take the full chord of the 2 winga as viewed from directly overhead and enter that number. I use 12% static margin (conservative) but it always seems to work.

Anyways cool plane.

i could watch bipes all day, there's something majestic about them

Originally Posted by rotagen

Been there done that. In reality if your 2 wings are close enough in incidence angle (decalage) yoiu'll be good to go, but believe me if you have a big difference in wing angles you want the bottom wing to stall first. My first biplane build I never heard of wing incidence at the time and of course I made the top wing pointing too far upwards and I kept messing with cg thiking that was the problem...long story short it had one too many terrible stalls and I threw it away.

Another one of my mistakes you can learn from, I was reading a lot of stuff on gliders and ran into a website that said Negative wing incidence relative to the horizontal stab is a good thing for an efficient plane. NOT.... Made a bf109 that way.... it flew great until I turned...then all hell broke loose... an aero guy could tell me why probably...again I kept moving cg forward to no effect.

Now I do most of my planes at 1.5% upward wing incidence relative to stab since my best flying warbird was made to that spec. BUT... I recently made a parasol wing before reading that you want zero incidence on those...I THINK?... anyways I gave it a pretty big wing incidence and I had to make the elevator real draggy to compensate.

Another thing I found it really does work if you simply assume the thing is a monoplane when entering the numbers into a cg calculator. That is, take the full chord of the 2 winga as viewed from directly overhead and enter that number. I use 12% static margin (conservative) but it always seems to work.

Anyways cool plane.

Thanks mate, I think it came out well.

And thanks for the interesting comments, biplanes certainly are a different kettle of fish compared to monoplanes!

As I said I went with about 3 degs positive for the upper, a little bit of positive tailplane incidence and the gap was a chord of the main wing , and I guessed the overlap. Probably had a bit of luck in my guesswork too!

Yes I'd call it a success.

Another fun bipe I made is one of the cartoon bipes, I think the thread title has the name "otto" in it, as in "Otto vs something or other". That thing flies well and easy to make with fat cartoon wings, I did a german one.

I write this wing incidence stuff out to remind myself not to make the same mistakes, and to bore people........ that too.