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Retractable undercarriage for warbirds

#1
Hi
Am a newb but keen to learn.
Really want to build lots of fairly realistic looking warbirds with retractables but not sure where to begin
Started another thread on this but that was assuming warbirds already built .
Hiidaflyer very kindly offered great advice on building your own but I think at the moment that’s beyond me!
What about fitting whilst it’s being built using retractable sets you can buy?
Have heard lots of horror stories about this
Questions include
1.is it possible on 30” wingspans or do I really need to scale up to 40”-so wheel actually fits inside wing?
2.can anyone recommend good but relatively cheap sets they may have used and I could buy from HK or Ebay?
Thanks for any help you can offer
 

quorneng

Well-known member
#5
The normal fixed undercarriage has quite a lot of 'give' in it, not only from the flexibility of the wire but also the way the wire is fixed in.
With retractable undercarriage the retract units have to be rigidly fixed so the wheels retracts accurately into the wheel well. This means retracts do tend to be more delicate than fixed and they also make a bigger mess of what they are mounted to if and when they do pull out.

Remember the rule for most full size warbirds id. "If you can't land on a 'prepared' airfield, retract the undercarriage and belly land".
 

Wildthing

Well-known member
#6
I love the idea of retracts and I think they are cool and I do have some but 99.9% of the time a slight little bounce or thump on landing and something breaks. I mainly now just use fixed landing gear with 3/32" piano wire, you hit hard you bend it and then you just bend it back and away you go. :)
 

FDS

Well-known member
#8
If you just buy a second hand Durafly foamy they have retracts already. I have seen those for under £150. You will spend a third of that buying the retracts.
When they make a master series Spit it will take retracts, as will the Corsair.
 

FDS

Well-known member
#10
You can order a Master Corsair off the US store, it will just cost you as much as a Durafly or similar ARTF by the time you add electronics and import tax and duty.
I would still build and fly a less detailed, cheaper model first, before going nuts with extras. You will crash it and a build that didn’t cost as much time and money is better for learning. The Nerdnic and FT spit are both great in 800mm size.
Then when you have mastered the skills required get a foamy with flaps and retracts to learn how to manage that. They are very scale and will fly like a kit build apart from being more over powered sometimes. If you then want to make something really detailed spend money on a proper kit. The flying club you went to might well gave a second hand foam warbird and recommendations for good first kits.
 
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#11
Just seen the corsair page,looks to be exactly what I,m looking for.
Looks like you can download the plans
https://forum.flitetest.com/index.php?resources/ft-corsair.62/&fbclid=IwAR12ronXD5OmRpgJhFWeyU8VtgI1vh_Qvy9PYUtdp5nVySoVmFlQAa92XWU
Can't wait for the spit.
Am currently working on similar techniques of bending foam from this
https://www.foamflying.com/hellcat-build---curl-and-form.html
Rolled my first piece today with a rolling pin.!
Felt more like Mrs Beeton than AJ Mitchell!,
Combining this bending technique with FT foamboard and their wings is the future I think.
Perhaps retracts and aerelons on wings is a bit too heavy/ambitious?
 
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FDS

Well-known member
#12
Not too heavy for a large wing. The plastic retracts are not that heavy, the main problem with doing it on smaller designs is that you have to cut a deep cavity into the wing structure to fit them, which can weaken the structure.
Ailerons are no weight at all, plus the servo is usually right in the wing or surface mounted. Flaps are harder to do, especially on thin wings. They are not ailerons (although you can make ailerons be flaps as ‘flaperons’) and are a separate moving part with their own servo.
Take some build pictures of the Hellcat!
 
#13
Here are the plans
https://www.foamflying.com/uploads/1/4/9/0/14901388/old_guy_rc_hellcat.pdf

Some useful videos I found on rolling .(I do mine on a soft pillow but cushions and beer bellies seem to be other good options
The next one shall be known from now on as the Dutch method

This one shows real improv -desert island stuff!

Am finding 1 section of Hellcat harder to roll -I need a bigger rolling pin -might try drainpipe /large water bottles -any other suggestions?( keep it clean!)
The master corsair build video seems to have another technique -rolling over the edge of a desk-might give that a try!
 
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FDS

Well-known member
#14
Table edge works, it did on my mini guinea nose and Sportster. The FT board can bend a surprising amount. I haven’t done too much foam rolling, since I have been sticking to more simple designs until I can fly without hitting things too often.
Bottles, even when full, may flex too much for rollers. 3” waste pipe is pretty good, look out for some in skips. I have used that in modelling projects in the past.
 
#15
Tried the table technique ,probably better for wings.Was going to try the Dutch method (see above) but..
As usual common sense is needed which meant i HAD TO ASK SOMEONE-FOR CONE SHAPEd fueselages USE BIGGER DIAMETER RODS/ROLLING PINS ON BIGGER END ,Smaller rods on smaller ends as your foam will only roll to the shape its wrapping round and not much further!!!
 
#16
Also old guy recomended the thinnest possible music wire.
i've got 1mm ie between a 1/32 and 1/16 inch –
Am a bit worried it’ll bend too much when attached to a servo and not operate the elevator/rudder-but he said
You can use coffee stirrers or small foam bulkhead with holes as guides
Your wire will do...its a compromise between weight and resistance to flexing
 

FDS

Well-known member
#17
I use Chuppa Chups sticks or receiver antennae tube for guiding the wire. It’s called Wire in Tube, it works like bike cable, the wall of the tube stops the cable bowing outward. You can buy dedicated wire in tube Teflon coated tube for use in model railway signalling control, they may have it at Model Shop Leeds.
Personally I reckon the difference between using 1.3mm and 1mm is not that huge, especially in an 800mm size build, you can always mount the servo a little further forward to compensate.