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The Webbit 'TWIST' the 3 in 1 model


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So here is the plan and I am aware that this is not most people 'cup of tea'
 
Something I have always wanted to try is a convertable fixed wing model. In that you can fly it as a fixed wing land,remove the wing and add on a rotor system and fly it as an an autogyro. Maybe even 2 types? one with a DB type short stub wing with counter rotating rotors on each tip and the other as a DC (direct control) head with a single 3 bladed rotor sat on top.
Tomorrow I will make a start on the 'fixed wing' airframe, try and get this complete and flown in a couple of weeks.
If this goes to plan I can then calculate the rotor size needed and the position of of the mast etc
I will try and figure how to add photos when I have some!
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3 hours work this morning and I now have what looks like a fuselage!
I was not happy when I placed my motor onto the bulkhead is it sat a little too far back for my liking. Having read a few reports that weight is added to most I made up a new bulk head. This is positioned about 20mm infront of the existing one, the original one has been cut out to aid with battery location.
My motor is a lower KV motor as Autogyros fly best on larger fine pitch propellors, this will also help with the the fixed wing 3D stuff (if I could do it of course!)
The one thing that concerns me is that autogyros like to have a bit of down thrust normally inline with the CG of the machine. Not a problem for the AG but how it will effect the Fixed wing version I do not know..only out at the field will tell I guess.
The tailplane was a little over size so I just added a couple of slots in both, no big deal.
 


 
More tomorrow....can we upload PDF'S? I can add my new former if it is of help to others that I have drawn on solid works?
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Had a couple of hours spare this morning so started on the wing, not yet complete but should manage to get on top of it later this evening. I will be using Emax 12g MG servos through out , I have used a few of these and for their size produce plenty of torque.
Motor is now fully cowled, this is split so that I can get at the motor. You cannot see from these photos but it  will be cooled via a duct opening underneath. I have made the front canopy a removable hatch so as I can fit the battery in and out.
 


 
 
More later

Edited By Richard Harris on 03/04/2011 16:38:02

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Cheers Chris.
 
Between finishing work and the kids getting home from school I managed to complete the wing bar for a couple of soft balsa need for the tips at the TE. I have also made up a duraluminium UC, I have widened the track compared to the plan. Autogyros are renowned for tipping over as they take off so a little extra always helps. I have made my rudder larger in size as this will help in 'autogyro mode' (if it gets to that stage!
Will hinge the tail feathers tomorrow and start creating balsa dust in readiness for the covering.
I have to say I am surprised just how quickly the Webbit has gone together, if anyone is 'thinking shall I have a go'..do it!
 



The above photo is the mounting beams for the aileron servo (one each side) sheeted over in 1.5mm balsa to align the surface with the rib capping off strips.
 
More tomorrow (if she lets me)
 
 
Rich
 
 
 
 

Edited By Richard Harris on 04/04/2011 18:54:26

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The wing is now ready to cover, I am waiting on some Toughlon from Steve Webb Models, he is also sending me another set of ribs for my 'stub' winged version free of charge 'what a great guy!'
I looked through my 'box of shame' for some some wheel spats but the ones I found were way to big and heavy.
With some of that pink B&Q insulation foam I carved up a set to suit (ish) the WebBit, and epoxied a ply mount to them. They were then coated in Liquid Wings and left for a couple of hours to cure, a light sanding and I will give them a coat of primer tomorrow.
Now I have nothing left in the box and the airframe is virtually complete, so I have started to make up the pod that will sit in place on the wing mount.
This will be removable with the use of 'lacky bands', to this pod will be mounted the rotor mast and hopefully the 2 servos needed will fit inside unseen.
Tonight I will try and calculate ...ok guess!..the position of the rotor spindle compared to the 'fixed wing' CG. The idea is to design in such a way that the CG does not change and I can inter change from one to the other.
 
More tomorrow I hope
 



Caught the wife out!!!...she said 'that makes a change to build one with a wing on', with the pod in place her reply was 'not another one! haven't you got enough' . We can never have too many toys
 
Rich
 
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Hi Bill...hope the op went well mate?
 
 
Chris,
Liquid Wings is a 2 part water based covering that is used to cover models, it will go over foam or wood etc and is self levelling. It gives a hard shell and is really light . Kind of like epoxy but without the smell and it goes off in a couple of hours. My local model shop stocks it , try a google search.
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Tim,
Yes that's the stuff , just from a UK supplier and renamed by the looks. It smells very much like PVA. It does add a nice shell to the airframe but it is more as a finishing coat rather than for strength.
Using it on a flat surface is easy but I had problems trying to get it even around a contoured surface. I now mix it leave it for 20 mins so that it thickens up and then apply it, seal the mixed solution and give it a second coat after another 20 mins.
I made an all depron indoor pusher and gave the fuselage a couple of coats of this stuff, it really is resilient to gym walls!
It must be primered at least 24 hours after application or the paint wont dry
When I first received it I thought that the tins were a bit small, but it does go along way.
 
Rich
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Pod and mast have nearly been made for the 'Twist II' version, the mast is made up from laminations of balsa as I am trying to keep it as light as possible.
I will do more on the head this weekend, but you can kind of see how it works. The rotors are able to rock back and forth for pitch control, there are2 tongues sticking up from the mast which the head slips into and has a pivot bolt. The head also tips from side to side which is very much like aileron control, this is hinged using standard 1/4 scale pin hinges.
Using this type of head (DC) you are in control all of the time.
An autogyro is impossible to stall, so if you had a 'dead stick' it simply floats vertically down. If you get the CG in front of the rotor spindle it should gently descend forwards. This is the reason why have swept back the mast.
With a head like this the servos are always under load (especially pitch) so it is always best to go with higher torque metal geared servos (enough torque to cover the weight of the model). I have chosen the Hitec 225 MG's of which I am waiting for. Until these arrive I cannot make up the control arms for the head. I will post some pictures when they are done for those that may be interested.
 
More the weekend hopefully
 
Rich
 


 
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Chris,
If this does get into the air ok I am more than willing to share the plans with anyone else who wants to give one a go.
Up until a couple of years ago I was into to fixed wings (still am), I got a little bored and tried one of these out. It must have taken 3-4 months and many repairs later before I managed to get a controllable flight without a breakage. That first time was exactly the same feeling as when I had my first solo with my trusty old Super Skyman way back then!
I am not a heli guy (though I do enjoy watching others fly them), but these things a very addictive. It strange when people say..but that's a heli, I have to try and explain as best I can that it isn't and is infact a variant of a fixed wing.
If anyone has never tried one they should at least once.
 
Looking forward to seeing you 3 different scaled WebBits, how small will you go?
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Richard,
 
I've scaled down to 3/4 and 1/2 size 30" and 20". Currently I'm doing the wings for the original one, but am slowed down a bit by other things needing to be done. I'm going flying later, this afternoon but when I get back dependent how far I am on with the wings I'll start the 20" version. All 1/16 balsa with a good bit of 1/32, just 2 channel on aileron elevator, with a cox 020 Pee Wee on the front, may even be a good bet for electric indoor. I'll do a blog.
 
Cheers,
 
Chris.
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Slow progress unfortunalty due to the unnaturally mild weather over the weekend which meant the start of some major alterations in the back garden (may be able to swing another building shed if I plan it correctly)
Everything needed to complete my version has arrived this morning so I have no excuses!
 
I have opted to cover this model in WM Toughlon, I have got 2 rolls of yellow which should be enough to cover all 'bolt ons'. With a hopefully a bit left over in case a repair or two is needed.
 
Made a start on covering the wing this morning and have added a couple of photos. Will do some more tomorrow morning before going to work
 
 
Rich
 


 

Edited By Richard Harris on 12/04/2011 13:03:01

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