Super piper cub 95 build

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Postby Phugoid » Sun Nov 21, 2010 3:28 am

That's not a bad idea, I think that the parts are too thin here for a model of this size, just use nice light wood to avoid having to add too much nose weight later down the line
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Postby ADW 123 » Sun Nov 21, 2010 10:08 am

ill only rebuild the stab though. i had to sand it down a bit so that it will fit nicely inside the slot. it is a lot stronger than the last one i have to say.
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Postby ADW 123 » Sun Nov 21, 2010 9:47 pm

phugoid, how did u keep the prop on? i am using 1.25x prop to peg length of rubber 3/16", but i was wondering how exactly you keep the prop from falling out when the rubber comes loose....
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Postby Phugoid » Mon Nov 22, 2010 3:30 am

I don't hold it in specifically. You will find that you need to make a spacer between the nose moulding and the prop bush otherwise the prop hits the nose moulding. If you make this spacer a nice tight fit the prop won't fall out. To be honest it's not a bad thing if it does fall out, especially if it is a goof flier, it will upset the glide and stop your model going O.O.S.

Ensure you make the spacer from something hard and glue it firmly in position. I took advantage of the spacer I fitted by making it tapered to give the model some down and right thrust.....
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Postby ADW 123 » Mon Nov 22, 2010 10:56 am

should i tighten the prop hook so then the rubber doesnt fall out inside the plane when the rubber loosens? im afraid i dont quite follow.... i understand the first part, but its not answering my question
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Postby lukebozek1 » Mon Nov 22, 2010 11:09 am

I think that I understand. After the flight when the rubber isn't under tension, the rubber comes off the wire hook/loop. You might have the rubber a tad too long, I would shorten it. I tried to bend the wire loop closed a little, but it still jumps off, falls inside and is a witch hunt to reconnect.
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Postby ADW 123 » Mon Nov 22, 2010 11:19 am

so i understand that now. should i just let the prop kinda fall out and hang out of the plane by the rubber when its loose and gliding down? or shouild i secure the thrust button on so it doesnt fall out?
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Postby Phugoid » Mon Nov 22, 2010 12:34 pm

I'm sorry to contradict Lukebozek1, but don't shorten the rubber, the longer it is the longer the motor run, plus a number of other things related to torque which can be helpful.

If you are worried about the rubber falling off the hook, then simply close the loop up a little so that the rubber can just squeze past as you need to be able to put it back on if you are using a winder once the rubber is fully wound, the other option is to make up your own hook, which is completely closed and put a winding hook on the front of the prop, when you wind yo just wind the whole lot....

I'll Post some pictures later......

The problem with the guillows kits as against others is the plastic nose cones which make life difficult. On others than I've built they have proper removeable nose plugs which allow for thrust ajustment and for the use of magnets and other such devices to hold the nose on if desired....
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Postby ADW 123 » Mon Nov 22, 2010 12:37 pm

ok, well i should be getting my tissue paper in the mail today.... hopefully..... we will see how we go. i think that the wing will look pretty good, and i didnt have to add to much weight to sturdy it up. should be interesting. i decided to use pins as a jig for my parts as they are drying. ill keep everyone posted.
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Postby lukebozek1 » Mon Nov 22, 2010 1:09 pm

Contradict me all you want, I have seen your stuff fly and you certainly know what works. I want to make sure that I understand this as I have one for the park now, a Javelin. Are you saying to leave one inch of slack in the loop to peg with extra rubber? Or are you saying that longer rubber (moving the peg back) would result in more power?I thought that once it goes slack we're done, Force equals mass times acceleration. That is all I remember from Physics in 1965.
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Postby ADW 123 » Mon Nov 22, 2010 3:54 pm

moveing the peg back gives more turns for the rubber if that makes sense.....got my tissue today.... start covering tonight :lol:
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Postby Phugoid » Mon Nov 22, 2010 4:13 pm

Don't move the peg back to get a longer motor in, the additional weight needed to balance the weight of the motor aft of the C of G will ruin things by increasing the dlift required and thus increaseing the drag

This is where it can get complicated if you let it. For long motors (these can be two or three times the prop to hook length) you have to braid the motor, braiding does a couple of things, firstly it puts tension into the motor and keeps the nose on, and because there is tension the winds don't "get lost" due to tensioning the motor initially as you pointed out. Secondly the motor never goes slack, and so the Cof G position doesn't shift during the flight so trim is not lost and the glide is not ruined. The braiding does reduce the wind capacity of the motor (I have read by around 10%) BUT you can pack more winds in, ie the longer the motor the more winds, the more winds the longer the flight

The compettion boys do all of this stuff to get tons of winds on, but I'm not into competition flying, I fly for fun and so I'm happy to get a 30 second flight, which means I keep things pretty simple, Thus I use relatively short single strand motors, not normally braided, if the are braided it's just enough to keep some tension to reduce C of G shift rather than anything else. OK you loose 50 winds or so to get the initial tension, but the extra motor length gives you another 200 or so.

To make all of this work you have to stretch wind the motor of course.

I hope all this makes sense, some of the above is first hand experience, other of it is what I have read, some more is what I've heard......
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Postby ADW 123 » Mon Nov 22, 2010 4:15 pm

makes good sense
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Postby Phugoid » Mon Nov 22, 2010 4:55 pm

Here's my FROG Redwing which is my favourite model. It's not the best for weight, it's not the best built or best looking. However it turns in 45s flights time after time after time. I must have had over 40 flights out of it.

This shows the proper nose plug. The hook, is fairly closed as I only have to put the rubber on to it at the start, the winding is done at the hook that also drives the prop.

Image

This is along motor for me, probably over 1.5 to twice the prop to hook length and is essentially unbraided. I can get in excess of 1000 winds into this motor although I limit it to 850 as it gets a bit twitchy due to the initial torque at high winds, I've never exploited the full winds potential, and because of that this is still the same bit of rubber that's always been with this model. When I'm done flying I take it out, wash it with soapy water to remove the lube, dry it and put it in an air tight bag for next time. The picture just shows enough tension to hold the motor out, I'm not really stretching the rubber.....

Image
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Postby ADW 123 » Mon Nov 22, 2010 4:58 pm

how do you get the rubber out and in easily? i know not to glue in the rear peg, but isnt it a pain to get the rubber in and to the back of the plane to the peg?
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