My backpack wing V1

[Hai-Lee]

A while ago I started building retro flying wings but found that whilst they flew very well they were a little clumsy to transport. I also noticed that the wings had a similar wing though scaled up or down to suit.

I wanted to make a series of planes totally different to those commercially available all based upon the same wing so that I could use the same foam core and not need to have a lot of different wing cores, (one for each plane design).

What I post here is my very first prototype of my first new series flying wing and this one is based upon the Balsa "Bubbles" design. Already I have found a few things I could do better but then this is only the first rendition and so it will undergo the required flight testing in the next few weeks. Hopefully the wings will survive to be fitted to the second version fuselage.

Here are the pictures for those who might be interested in progress so far.

The Pieces



Wing servos plugged in and spar tube inserted into both wings.



Awaiting it first test flight




That's all for now!

Have fun!

 

[Fluburtur]

ooo fancy, kinda reminds me of the backpack flying wing rctestflight made

Btw how is the pitch with those tailless planes?

 

[Hai-Lee]

Pitch is a little more sensitive then the FT and similar planform wings BUT if you know how to vary the mix ratios you will find them incredible.

Having built a few different versions in the past both tractor and pusher I have found their maneuverability to be awesome and their stability to be very good once set up properly.

hopefully the basic design will lead to a family of tailless designs and conventional versions all using the same wing core or layout. Sort of like having swappable fuselages rather than just a powerpod.

This Post is for the FB flying prototypes and plans may be made available for those that would like to try one! Hopefully the final versions will be XPS, EPO or EPP foam.

Have fun!

 

[Hai-Lee]

It flies!!!!

Had 2 flights this morning. The first I had set the elevons for about 3 mm of reflex and took off. Wrong settings obviously! The plane pushed its nose up and was "Nodding" badly which showed that I had way too much deflection of up elevon and the speed was too low for the settings I had. Flying it around with a half stick of down allowed the speed to build and I quickly landed it.

Adjusted the elevon deflection for zero up or down and took off again. This time it fly brilliantly reasonably tight loops and quite fast rolls. Rudder if SUPER effective and needed to be used with caution as coarse rudder would quickly put you into a nose down roll. That means that it has a great amount of authority and it works well for taxiing so I will live with it and learn to exploit it as I get used to its flying properties.

Judging by the "Ohhs and Ahhs", it impressed a lot of the other pilots at the club as well.

Anyway, Next fuselage already on the drawing board!

Having Fun!

 

[Hai-Lee]

Had a break in the rain yesterday and took the model out for further test flying. Sadly the rain had stopped but not the wind. Very gusty and close to the upper limit of this planes ability to make headway but then again I did have the field to myself.

After a few flights I tried something different by trying to do a short field landing and as I was crossing the tree line to line up for the landing the wind suddenly died and the model flew straight into a big gum tree about 100ft in the air. As usual it stopped suddenly and then started the branch to branch pinball maneuvers until it stopped in a fork of the tree about 60ft above the ground.

I managed to get it down using tried and tested ground based recovery techniques and once down I checked the model for damage. there were a few surface scrapes, a hole in a wing tip piece and a splintered CF wing spar. Patched the hole and fitted a new wing spar and ready to go again!!

Turned out to be far tougher than I had envisaged!

Have fun!

 

[xMeox]

Very interesting design! I tried to design something similar years ago, but for slope soaring. Though I never managed to get a good connection with replaceable wings. Can you share some information on how you managed to fix them once the spar is in?
Thanks in advance,

Martin

 

[Hai-Lee]

Martin,

The 6mm dia spar fits into a 6x5mm rectangular spar tube made from FB of course with end stops to limit spar travel.
The spar is a very tight friction fit and the wings key into the fuselage without any other holding mechanism outside the spar friction. During the treeing event the spar splintered, (bent), in the centre section and the wings were pushed backwards and outwards a little and so saved them from a lot of damage.

When flying the friction is actually increased as the wings are loaded so they do not move even when subject to some extreme aerobatics. I have the ability to add tongues for fixing with screws but so far no need.

As for the design I did a quick "Hack" of the RCM design called "Bubbles" the plans for which I downloaded from www.outerzone.co.uk

Have fun!

 

[Hai-Lee]

Just an update! (I got a new camera). YES! It is still flying!

Here is the KEY in the fuselage side.


The FB Box spar in the wing as well as the Servo lead exit point.


The CF Spar fitted into the wing box spar


Elevon servo connected


Wing keyed into the side of the fuselage!


Both wings connected, and keyed into fuselage


Just hanging around. Hanging on the wall from the top wing pushrod over a large screw.

Even after 15 months of treeings, somersaults on landing, severe hangar rash and often extreme mishandling the wings still will not slide off of the CF spar without significant effort. Only the friction of the CF tube in the FB box spar holds it all together.

Have fun!

 

[Hai-Lee]

Updated the previous post! I somehow managed to forget to post the "Hanging" photo.

Photo added!

Have fun!

 

[vhandon]

I am going to add the wing key in the fuselage of my current build! Wish I would of thought of it myself. Do you just use tape to secure the wings to the fuselage?

 

[Hai-Lee]

No tape! Just a very firm friction fit. The FB wing spar has a 5x6 mm cross section, (with a depth end stop make of FB also), and the 6mm dia CF spar is force fitted, (with a minor amount of lube for first fitting only). After that once the wings are pressed home the friction makes the wing very hard to move and the key in the fuselage side of course stops the wing from twisting in flight!

I have treed it a few times and the worst was when the CF spar splintered where it went through the fuselage but the wings popped out about 50mm total and folded back along the sides of the fuselage as it bounced from branch to branch all the way own and out of the tree, I just cut and fitted a new CF spar and flew again a matter of minuted later!

IF you fear that the wings will come loose over time you could add a myriad of other restraints but so far my model has not needed any such additions. As always you need to make the plane safe in your eyes so you could tape. velcro or even add tongues and screws to add additional security but for 15 months of abuse the wing holds and flies as it did on the very first day! For larger wings the use of 2 spars would make it incredibly strong and hold even tighter.

it was posted as an idea for those who want a simple backpack arrangement to explore and develop to suit their own requirements!

have fun!

 

[FoamyDM]

Sounds like I need to start using this technique, as my planes are close to exceeding my car capacity.

I picked up CF Arrow Shafts a while ago... (where did I put them away at?)
As always - Thank you for sharing this Hai-Lee

Do you make the former around the CF or shove the CF after and the FB gives a bit? (If I just do it, I'll find out, wont I?)

 

[Hai-Lee]

Sounds like I need to start using this technique, as my planes are close to exceeding my car capacity.

I picked up CF Arrow Shafts a while ago... (where did I put them away at?)
As always - Thank you for sharing this Hai-Lee

Do you make the former around the CF or shove the CF after and the FB gives a bit? (If I just do it, I'll find out, wont I?)

I measured the CF diameter first and then made the FB box/tube spar holder deliberately smaller. A slight rounding of the ends to the CF spar ends with a little sandpaper and the lightest amount of lube, (I used a petroleum grease) and then forced the spar into the FB tub up to the stops. It took a bit of force the first time and is never a drop in fit but it is very solid and reliable even after more than a year!

have fun!