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Jan 03, 2018, 12:20 PM
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Question

Dethermalizer?? ... Props??..


Hey Folks, I could use a little advice on this contraption. I'm on a little free flight kick lately ( never built them before) , I thought it would help me learn to build more lightly, I tend to built a little heavy and am pretty heavy handed so I decided to build B.T, Faulkners' Yardstick for shitz and giggles. Unless I"m missing something there is nothing on the plan on the mechanics of the dt. ( not even going to get started on the prop gizmo yet) So what would be the best way to do this? I'd like to activate it by radio but keep the rest old school.
Thanks
Martin
Last edited by remitt; Jul 01, 2018 at 01:25 PM.
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Jan 03, 2018, 03:48 PM
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gossie's Avatar
You will notice the hooks at rear......A small band was there holding the tail down, and a fuse in there, lit, and when it burnt through the band the tail went up and bought the model down.
These days we often use a clockwork timer, but R/C can be used.
You need to have a band hooked to a hook on top of the tail and around the fuselage to pull the tail up to about a 45 degree angle.
Jan 03, 2018, 05:42 PM
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gossie's Avatar
With respect, Yardstick is probably not the best model for a person to build without F/F experience.
May I suggest you have a look at SENATOR. Simple to build, a good size so it's not fiddly to build, and a fantastic flyer with a free wheel propeller.......Plans are available on the internet and thousands have been built.
I've built five of them over the years, and they have been winners for me.
Jan 03, 2018, 05:43 PM
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A light came on after I looked at your pic. One of the things that was giving me grief was the triangle shaped fairing attached on top and at the front of the stab. When the stab goes up that triangle is supposed to tuck inside the fuse. I had the triangle built as wide and tall as the fuse so it was flush and pretty to the outside of the fuse. The plan doesn't show any pegs for bands other then the motor peg so I am trying to figure out how to hold it down until it is deployed. where would you hook the band at the forward end? The vertical stab will be fasten permanently. Also, I think the stab will slide up to the under side of the fin when it's released.
Jan 03, 2018, 05:48 PM
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I have built a couple simple ones early in the summer to play with, the yardy won't get flown for a while, at least by me, I couldn't reset building the geoditic wing.... and thanks for posting the pics and advice!!!!
Jan 03, 2018, 07:42 PM
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gossie's Avatar
Quote:
Originally Posted by remitt
A light came on after I looked at your pic. One of the things that was giving me grief was the triangle shaped fairing attached on top and at the front of the stab. When the stab goes up that triangle is supposed to tuck inside the fuse. I had the triangle built as wide and tall as the fuse so it was flush and pretty to the outside of the fuse. The plan doesn't show any pegs for bands other then the motor peg so I am trying to figure out how to hold it down until it is deployed. where would you hook the band at the forward end? The vertical stab will be fasten permanently. Also, I think the stab will slide up to the under side of the fin when it's released.
You need a hook a bit behind the leading edge of the tail, with a band on it wrapped around the fuselage and back again, or a peg low in the fuselage to hold it, that then will pull the tail up.
Up to you to hold the rear down, probably with fine fishing nylon line from a hook, through a tube, along the fuselage to your servo.......as you can see on SENATOR I use a clock work timer.

Personally I would forget the triangular bit on the rear of the fuselage, just make a mount for the tailplane.
Jan 03, 2018, 07:48 PM
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Norm Furutani's Avatar
Sounds like you've gone past the point of switching projects, as Gossie suggested (and I agree!). So, as for a DT, I would run a dowel (red circle) under the longeron, sticking out on both sides. Add stop blocks (both sides) in front of the stab (red rectangle). Add hooks on both sides of the fairing. Attach the stab with rubber bands from the hooks to the dowel. You need about a 45 degree tip-up for the DT. If you're lucky, the fairing will hit the dowel and stop at the right angle. You will need a line at the rear that pulls the stab down and goes forward to your servo. You can incorporate a stop in the line that will give you the 45 degrees. Mounting the radio is up to you. I would put it at the CG or far forward as possible if weight is needed to balance. Mind the rubber motor that goes through the fuselage.
Jan 03, 2018, 08:28 PM
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I'm going to check out Oz for something suitable (if not the Senator) and join the build off in the vintage forum. I started the Yardy a couple months ago so it's not eligible. When I get the Yardy finished it can hang off the ceiling for a while until I'm more comfortable with flying it or I run into someone I think is competent enough to loose it in a thermal.
Last edited by remitt; Jan 03, 2018 at 08:34 PM.
Jan 04, 2018, 12:11 AM
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gossie's Avatar
Quote:
Originally Posted by remitt
I'm going to check out Oz for something suitable (if not the Senator) and join the build off in the vintage forum. I started the Yardy a couple months ago so it's not eligible. When I get the Yardy finished it can hang off the ceiling for a while until I'm more comfortable with flying it or I run into someone I think is competent enough to loose it in a thermal.
Ask Bruce nicely if he will accept Yardy.
I've built and have more rubber models than anybody else in the world.....Well maybe, so at this stage I just don't need another big proper build.
I did start a Junior Miss by Vic. Smeed last year for my young Grand Daughter to fly with me down the park.......She chose it, but at this stage it's only part finished, so I ask Bruce if that was okay rather than me building something new..........It was accepted.........Thanks Bruce.

I'll get it out soon, take a pic or two, and join in, as you should with Yardy, that I know well, and it's a good rubber job. Go for it, but ask Bruce first of course.

P.S. Thanks Norm. Great post. We need all the Freeflighters we can get. It's a dying art.
Jan 04, 2018, 12:33 PM
B for Bruce
BMatthews's Avatar
Your Yardie is using that little fairing as the positioning key near as I can see. But it's pretty fuzzy on how it actually keys to the fuselage. I'm thinking the fairing on the stab should fit between a couple of rearward angled square pieces so it can't move side to side but can swing down into the fuselage when the tail is pulled up. But that's a nasty bit of tinkering.

All in all I think I'd ditch that and just put a regular DT rest on the fuselage and modify the front of the tailplane to give me a long enough straight edge that it can mount there and hinge up normally.

And very few plans show all the little hooks needed for DT systems. Designers expect others to do what they do. For example I hate the fuse and I only rarely use fuses anyway. So I'd bend a curved guide from aluminium tubing and run the line to a modified Tomy Toy timer under the wing or near the landing gear on models with gear. And with that already there my travel limit is another small piece of aluminium tube crimped to the hold down line so the tail only goes up so far. For radio DT you'd need to do something similar.
Jan 04, 2018, 07:01 PM
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Thanks guys, I've have alot to learn about this discipline. I can see building a few a year just so I can have fun with my grandson and maybe teach him a little about it. Every time I see him he runs to my truck to see if/which plane I brought with.
I'll probably set up the D.T more along the lines you gentlemen suggest, though I need to do some research as I don't fully understand the mechanics, but for shitz and giggles I'm going to try to get one to work as per plan just for the experience. I might switch to a timer as well in stead of the servo setup. What should I expect the weight before motor to be? The model pictured above is Ted Straders' "Whippet" reduced to 24", weighs 2.6 ounces with motor, I think that's good??? It flies pretty good.
Jan 04, 2018, 11:16 PM
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BMatthews's Avatar
Buy a Texas Timer or one of the electronic ones. But really if you fly these in city or town parks or sports fields the radio DT isn't a bad option at all. You can maximise the flight time and with radio you can drop it on the upwind side of the turn to shorten the retrieval or give yourself more clearance from the tree line or other field boundary. So for in town free flighting I'd say keep the RDT.

2.6oz for 24" isn't bad for sport flying. But being honest it's not great either. It would not be out of the question to see it come in closer to 2oz even.

A big help would be to ditch the big heavy wheel collars you're using on the LG in favor of small light washers soldered on using just a kiss of a fillet of solder. I'll bet you save a good 1/4 to 1/3 oz right there.

Learning to pick your wood for density is a big part of lightweight building. When you do use harder and firmer wood for strength do so knowingly. There's main fuselage longerons of course. And wing spars. And for sport flying models I like to use medium hard wood for the leading edges because sport models are more subject to dings off "stuff" and it's not fun to repair busted leading edges. But most everything else I try to use contest or near contest grade light wood.
Jan 10, 2018, 12:56 PM
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This is too much fun, I loved building this wing!!! I even managed to get the little fairing to tuck into the fuse when the stab is up. I'm having a bit of trouble trying to get the thread hidden in the fuse and have it work properly so I might leave the string on the outside and bury the rest, I'm going to keep it rdt... I have paid alot more attention to balsa density. I changed the wheels on the little whippet to balsa wheels, never made them out of balsa before, and soldered small brass washers on to keep them secure, also changed the rubber bands out to thinner ones. I made an error before, it weighed 2.3 oz now it's down to 2.1 . My scale is not that terribly accurate so assume .05 error in weight either way, a good scale is on the short list this year. I am taking your advice and will build something a little more suited for a beginner free flighter, Maybe a Miss Canada, eh.
Last edited by remitt; Jan 10, 2018 at 01:30 PM. Reason: add text
Jan 10, 2018, 05:18 PM
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gossie's Avatar
Good work, and 2oz is fine.
Jan 28, 2018, 02:53 PM
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Another fun build! Can't wait to try this one out. Prop, thrust bearing, rubber , all the little incidentals are ordered. I read somewhere to keep ff rubber models under 3oz/100 sq in and they generally fly ok... is that true? This Senator should be under 3oz (140 sq in) when completely done.


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