Official Freewing Twin 70mm AL37 Airliner Thread

[GliderGuy]

I designed those NG winglets on thingiverse (the lawn is much healthier now lol) - they're reasonably true to scale based on some diagrams I found online and have the same aerofoil shape as the AL37 wing (literally took the existing aerofoil profile, extended, shaped and bent it). Flying without any winglet at all makes the AL37 marginally less wobby if there's a breeze about IMO. Havent noticed any difference in flight characteristics between the stock Max-8 winglets or the 3D printed NG style winglet, although the stock winglets that came with mine never really sat flush on the wing which had a minor impact on trim.

In full scale the winglets offer marginal efficiency improvements, which i guess is important if you're burning 800 gallons of avgas an hour. I'm not appropriately qualified to opine on their impact at our scale, alpha probably has some insights though.

Not the easiest part to print; so unless you absolutely must have the 'blended' look of the NG winglet I'd recommend just modifying the ones it comes with.

I can absolutely state that the stock AL37 winglets do have a significant impact on the aerodynamics. While I was waiting for the glue to dry on one I had slightly damaged, I decided to make a flight with only one winglet in place. Since a winglet, in effect, aerodynamically extends the wing span of the wing (also reducing the drag), the AL37 had a bad roll in the direction of the wing without the winglet. Said another way, if the right winglet is not in place, the roll is to the right because of the "in effect' longer left wing.

Needless to say, after that rather interesting experience...I waited for the glue to dry on the repaired winglet before making another flight. I anticipated a roll, but not as much as I encountered.

-GG

[Alpha]

GliderGuy is right, the winglets do affect the AL37. In full size, winglets are optimized to reduce drag. In a model of this scale and made from these materials, the efficiency is less noticeable (don't expect to fly a minute longer with the winglets on versus off, for examples). What is more noticeable, however, is how the wingtips behave in space. As GliderGuy observed, the increased lift needs to be equal, so I would never recommend flying with only one winglet. We did that in the test phase and it was, let's say, "less effective".

As for adding aftermarket winglets, we're not pursuing optimal math here, so I think the approach mshagg used with his 3DP design is more than acceptable. There of course will be a threshold where too tall or too thin or too much sweep becomes problematic, but in general, extending the wingtip's shape (converging existing LE and TE) and extending it upward is fine.

More important for this model than the shape itself of a wingtip device is its positioning. You'll want both winglets to encounter the airflow in a consistent manner, so ensure that the mounting pegs are consistent (3D Printing solves this problem where back in the day we had to fabricate symmetrical pairs!). If one is canted outward or inward compared to the other, you'll notice a difference in flight behavior and should expect to have to trim for it.


We could talk for a long while about winglet design. To summarize, the objective is to reduce the tip vortices, which will in turn reduce drag and impart stability. The variables at play when shaping a winglet include twist, toe, sweep, and cant. The root cord, tip cord, and sweep help design the overall shape of the winglet, while relative AoA (cant) and its origination point along the root chord help position the winglet vertically in reference to the wing. Tweaking that base angle, and also the tip angle, further complicate things, as does variations in the radius' angular transition from wing to winglet (obtuse or even acute!). All these variables will affect an aircraft, a full size moreso than a model. "Optimum" performance also depends on an airspeed range. This is where model-specific design diverges more noticeably from full size aircraft design, but I digress.

I enjoy reading of everyone's exploits and additions to our bird!

[Ian H]

Finished the paint job today. Looks great in the air.

[mshagg]

Mounting an action camera at the base of one of the winglets is also a terrible idea if you like a plane which behaves consistently throughout its roll axis. Or, so i hear.

But it does make for some great shots, as demonstrated by QF667 on short final into YPAD (notwithstanding bank angle far in excess of SOP).

[Aros]

Finished the paint job today. Looks great in the air.

Just plain gorgeous. I've said it before and it's worth repeating...These custom liveries have been outstanding! No other RC model that I am aware of in mass production has ever had near the diverse, fantastic custom offerings from customers.

[Aros]

I'm not finding a lot of photos of them but I am partial to the blended (not canted) winglets that have a significant curve at the base like the ones below. Most I see are more angular. Not sure what the aerodynamic difference would be however...

[mshagg]

Im biased but agree they look so much better. It's the backwards sweep that makes the radius of the blend look larger than it really is from certain angles.

[Slowflight]

GliderGuy is right, the winglets do affect the AL37. In full size, winglets are optimized to reduce drag. In a model of this scale and made from these materials, the efficiency is less noticeable (don't expect to fly a minute longer with the winglets on versus off, for examples). What is more noticeable, however, is how the wingtips behave in space. As GliderGuy observed, the increased lift needs to be equal, so I would never recommend flying with only one winglet. We did that in the test phase and it was, let's say, "less effective".

As for adding aftermarket winglets, we're not pursuing optimal math here, so I think the approach mshagg used with his 3DP design is more than acceptable. There of course will be a threshold where too tall or too thin or too much sweep becomes problematic, but in general, extending the wingtip's shape (converging existing LE and TE) and extending it upward is fine.

More important for this model than the shape itself of a wingtip device is its positioning. You'll want both winglets to encounter the airflow in a consistent manner, so ensure that the mounting pegs are consistent (3D Printing solves this problem where back in the day we had to fabricate symmetrical pairs!). If one is canted outward or inward compared to the other, you'll notice a difference in flight behavior and should expect to have to trim for it.


We could talk for a long while about winglet design. To summarize, the objective is to reduce the tip vortices, which will in turn reduce drag and impart stability. The variables at play when shaping a winglet include twist, toe, sweep, and cant. The root cord, tip cord, and sweep help design the overall shape of the winglet, while relative AoA (cant) and its origination point along the root chord help position the winglet vertically in reference to the wing. Tweaking that base angle, and also the tip angle, further complicate things, as does variations in the radius' angular transition from wing to winglet (obtuse or even acute!). All these variables will affect an aircraft, a full size moreso than a model. "Optimum" performance also depends on an airspeed range. This is where model-specific design diverges more noticeably from full size aircraft design, but I digress.

I enjoy reading of everyone's exploits and additions to our bird!

My mod on the winglets was simply to eliminate the lower section on the supplied parts, but as you can see from the pictures the latest version os the PA8 uses a different wing tip, no idea as to the reason, what little I know about wings those should provide some additional lift and perhaps add some drag as a consequence of the additional lift. Now that I’ve flown it and I know how it behaves I will be making some like the new PA8, no 3D printing just some old fashion balsa and ply covered in fabric. I think this latest version looks very cool, any thoughts on how it may affect the AL37 based on your tests?

[Hugh Wiedman]

My mod on the winglets was simply to eliminate the lower section on the supplied parts, but as you can see from the pictures the latest version os the PA8 uses a different wing tip, no idea as to the reason, what little I know about wings those should provide some additional lift and perhaps add some drag as a consequence of the additional lift. Now that I’ve flown it and I know how it behaves I will be making some like the new PA8, no 3D printing just some old fashion balsa and ply covered in fabric. I think this latest version looks very cool, any thoughts on how it may affect the AL37 based on your tests?

Hey Roger, we missed you flying that last Friday. The runway is now outstanding, better than before at less than 1/2". All my jets got off with ease, me one happy camper. Your AL 37 should now take off in 10 feet instead of 20! And you missed the kielbasa as well, but more for us!

[Slowflight]

Hey Roger, we missed you flying that last Friday. The runway is now outstanding, better than before at less than 1/2". All my jets got off with ease, me one happy camper. Your AL 37 should now take off in 10 feet instead of 20! And you missed the kielbasa as well, but more for us!

Did you like the new toy? I had some stuff here at home I had to take care off, Marks suggested we go a couple of times next week weather permitting !!!

[Belgenland]

Hi
I'm Philippe from Belgium. I'm finishing a Brussels airlines livery and I'll post pictures in the appropriate section.
I'm experiencing troubles connecting the blue box on a Spektrum AR9030T receiver... It looks like channels are not linking properly when connecting ail to ail, rudder to rudder etc...
If someone flying her using a Spektrum rx/tx...could you please advise if any specific setup is required?
Thank you
Phil

[Slowflight]

Hi
I'm Philippe from Belgium. I'm finishing a Brussels airlines livery and I'll post pictures in the appropriate section.
I'm experiencing troubles connecting the blue box on a Spektrum AR9030T receiver... It looks like channels are not linking properly when connecting ail to ail, rudder to rudder etc...
If someone flying her using a Spektrum rx/tx...could you please advise if any specific setup is required?
Thank you
Phil

Im using a 9030 had no issues, I connected it as per instructions , Maybe is how your radio is set up?

[xviper]

Hi
I'm Philippe from Belgium. I'm finishing a Brussels airlines livery and I'll post pictures in the appropriate section.
I'm experiencing troubles connecting the blue box on a Spektrum AR9030T receiver... It looks like channels are not linking properly when connecting ail to ail, rudder to rudder etc...
If someone flying her using a Spektrum rx/tx...could you please advise if any specific setup is required?
Thank you
Phil

There is nothing special about hooking this plane's leads to any receiver. If you have everything plugged into the blue box and then use the pre-connected leads from the blue box to the RX, it's very straight forward. The only thing I can think of that you may have done is to designate the incorrect aircraft type (wing type) in your TX. It should be "1 AIL, 1 flap, normal tail". If you are using the blue box as it came and you are telling the TX that you have 2 AIL and 2 ELE, it won't work.
If you are by-passing the blue box for the primary control surfaces, then it's still the same "wing type" but you must "Y" the 2 ailerons together and "Y" the 2 elevators together, so you have only one plug for each for the RX, unless you really want to have separate ELE and AIL channels.

[Steve Corbin]

I found this site today and have been enjoying reading some forums.I would like to have a jet airliner style model for flying on the many Slope sites near me. In fact I would have to drive a healthy distance if I wanted to fly off a runway in a field.
Are the airframe components for the AL37 available without all of the stuff needed for powered flight? While flaps would be appreciated I would have no use for landing gear, and engine nacelles must allow minimal resistance to airflow.
I looked at the Freewing site and I must say that a AL37 motorized plane would be a hoot to have I simply have no place to fly one even if I could afford to buy it, so a glider version is the only way I can enjoy the looks of an airliner model plane. I have some Chinese foamy motor gliders and a couple Hobie Hawks but I have always thought that the jet airliners look graceful, and the original Lear Jet has been a long time favorite.

[Alpha]

Steve Corbin Welcome to Hobby Squawk, Steve! Our AL37 is only available as a PNP (Plug-'n-Play), with everything pre-installed except the pilot's provided receiver and flight battery. We don't sell a KIT version of this aircraft. Perhaps tally up the main foam parts in the Spare Parts tab to see what it would cost you to piece one together a la carte, plus your own extra modeling effort to bring it all together for your slopes:

https://www.motionrc.com/products/fr...pare-parts-tab


I will say though that this bird would do well on a slope, in addition to being very unique compared to the models usually out there!

[Steve Corbin]

Yes the AL37 would look cool on my slopes, but I think that I will be setting up a hot wire because the AL37 is just way too small, Airliner models need to be in scale with the other PSS ( power scale slope) gliders on the hill, so if a P 51 has a 37 foot span and a B737 has as much as 147 foot span and the PSS Mustang has 72 inches of wing, then an airliner PSS glider should have a span somewhere in the neighborhood of 20 to 24 feet. Well, not to worry because I am not quite so Anal enough to go that far into the true scale world. But an Rc airliner of my own design ( with a nicely styled fuselage kinda like a Connie) with a 16 foot span would be just oh so cool, and would look right in the air with all the other PSS gliders, Ya know, the DeHavilland Comet could be made to look really nice.......

[V12Kid]

Gents -

I am almost done assembling my AL37 and I have a few questions.

I used blue painters tape to mask the belly so I could paint it and when I removed the tape it took along some of the paint with it. What color can I use or buy to fix the damaged area?

I also noticed the winglets don't fit flush with the ends of the wing? is this normal? They seem off even though I slid them on with pretty good force.

Any insight is appreciated

[Gravity Wins]

HELP! Where does the BEC plug into? The instructions and diagram completely omit it and I found the lead loose up by the cockpit. Need to know so I can power up, bind, and lower gear to continue assembly.

[mshagg]

Anywhere you want. Either a free port in the rx (probably ideal) or in the multi function box. All of the red wires in the plane share a common power rail.

[Gravity Wins]

Anywhere you want. Either a free port in the rx (probably ideal) or in the multi function box. All of the red wires in the plane share a common power rail.

THANK YOU! One simple line in the instruction sheet could have prevented the halt. Thanks again!