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Sabre Rattling time

Dannys F-86 Sabre PSS build blog

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Danny Fenton09/11/2019 22:01:50
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9615 forum posts
4430 photos

Thanks Peter, being a novice I don't know how much these models need to be slowed down before arrival.

I think I will keep it simple..... those that know me may wonder, if that is indeed possible crook

Thoughts on the rudder?

Cheers

Danny

Edited By Danny Fenton on 09/11/2019 22:02:19

Edited By Danny Fenton on 09/11/2019 22:03:35

Martyn K09/11/2019 23:02:39
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5083 forum posts
3678 photos

Agreed. Thanks Peter, that is useful to know. I'll drop the flaps (no pun intended) as well - K. I. S. S

Martyn

Chris Barlow10/11/2019 02:04:12
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1904 forum posts
1308 photos

I like having a rudder as I use it a lot in the landing phase to side slip to scrub off speed and to make flatter turns when I get off course too close to the ground. Having a rudder has also saved me when caught out either by mis judgement or rotor/turbulence when the model just wants to flip over faster than I can roll it back with just ailerons.

Generally though, I don't use rudder much during normal flying. There's usually (sometimes) so much wind that bank & yank are all that's needed with so much speed and energy.

I think for my Sabre I'll go with a rudder but not flaps, that big hole up front should slow it down enough!laugh

Martin Gay10/11/2019 10:54:43
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396 forum posts
255 photos

Interesting discussion about flaps.

I use them all the time on my slope models. If the lift dies I droop them a couple of mm to increase the wing camber and help get me back to the top of the hill.

I also use them for CROW braking - very useful when you have to land in a restricted landing zone.

As Peter says, they can be damaged if left down on landing, but it is easy to clean them away just before touchdown. I find spoilerons drop the model in quick whereas CROW allows me to land with almost zero forward momentum, if done properly.

The German TA154 I flew on the Orme just hovered in vertically with full flap deployed!

Danny Fenton11/11/2019 16:53:14
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9615 forum posts
4430 photos

Thanks Martin, now you have me pondering. So if I understand "crow" means flaps down and ailerons up? Forgive my ignorance Martin crook

Cheers

Danny

Martyn K11/11/2019 17:00:26
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5083 forum posts
3678 photos

I am going for a rudder and now having third thoughts about flaps. I'll probably not bother though as its quite a draggy airframe

Yep - Crow is as you described - an effective lift and speed shedding formula

Martyn

Martin Gay11/11/2019 22:19:47
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396 forum posts
255 photos

I would recommend fitting the flaps. Yes, it is a draggy airframe but it is also a quick model.

Just because you have them doesn't mean you have to use them all the time, however, once you get the hang of using CROW (flaps down and ailerons up), you will be happy you have them fitted.

Danny Fenton11/11/2019 22:46:11
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9615 forum posts
4430 photos

Thanks chaps, obviously this all adds complication and additional servos..... all increasing the wing loading. But I appreciate you sharing your experience and will do as you suggest.

Cheers

Danny

Martin Gay12/11/2019 09:06:58
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396 forum posts
255 photos

A couple of 13g servos and linkages will not increase the wing loading by much.

The prototype Sabre was 4lb in weight and roughly 2.78 square feet if wing area which works out to be 23oz per square foot wing loading.

Danny Fenton12/11/2019 22:09:25
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9615 forum posts
4430 photos

Hi Martin, you are talking to someone that is fanatical about saving weight

I hope to use RDS for both the flaps and the ailerons, possibly even the rudder too. never used RDS for a rudder this model should prove a good platform to try that and my new 3D printed RDS adaptors.

I noticed on Daves Sabre thread you talked about stencils, if anybody does the Luftwaffe Sabres I am happy to share the masks I cut, if it helps somebody else

Put in my SLEC order today, not quite as cheap as I expected, but what the heck, you can't take it with you.....

Cheers

Danny

Flyer12/11/2019 22:35:06
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616 forum posts
108 photos

Hi Danny,

Any chance doing a few post about the RDS adaptors; I'm sure this would be useful. Especially as quite a few of the lads have access to 3D printers.

Cheers

Ade

Danny Fenton12/11/2019 22:51:42
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9615 forum posts
4430 photos

Hi Ade, yes sure. I actually get a friend to print them for me as I haven't taken the plunge yet. But the beauty of this design is that they will fit any servo and are not restricted by spline size/type.

Should be able to mount all four servos in the wing root, with the RDS rods at 45 degrees to the surfaces.

Cheers

Danny

Chris Barlow13/11/2019 00:45:17
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1904 forum posts
1308 photos

How robust are the RDS adapters Danny? I have found that PSS models tend to get more abuse due to the less clinical environment compared to a neat flying field. Assembly of models is usually out the back of the car and landings can sometimes be better described as ditchings, especially in heather and clumpy grass!

There is an RDS adapter on Thingyverse here. Is that anything like yours Danny?

23b09dca24c3f142617fc952734721e0_preview_featured.jpg

David Sack21/12/2019 08:38:04
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31 forum posts
39 photos

Hi Guys, I want to go down the RDS route too. The only accessible versions I found were on the Graupner site.

https://www.graupner.com/RDS-Servo-lead-duct/JR/3925/ A bit pricey perhaps, especially with postage. This seems to be the right size but I am no expert and was hoping to tactfully, but unashamedly, follow someone elses experience.

If someone is printing these adapters and sharing - count me in !

Edited By David Sack on 21/12/2019 08:40:27

Ron Gray21/12/2019 09:28:26
2134 forum posts
936 photos

RDS are used quite a bit in the F5 / F3 areas, have a look on Hyperflight

Danny Fenton21/12/2019 12:35:49
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9615 forum posts
4430 photos

432.jpg

This is my implementation. I have got some 3D printed adaptors for the servo output arms.

The bit that will wear and cause slop is the torque box. I line mine with melamine so that it is very hard wearing.

Maybe this will help?
Cheers
Danny

Danny Fenton21/12/2019 12:38:34
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9615 forum posts
4430 photos

A friend (Eric Strefford) is printing these for me.

443.jpg

Cheers

Danny

Danny Fenton21/12/2019 13:21:59
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9615 forum posts
4430 photos

The problem with commercial RDS adaptors is that they are manufactured to fit specific servos, more accurately their splines. These that I use are universal and bolt onto a supplied cross output arm, which virtually all servos come with.

When set up correctly they are very robust. But be aware of the weight, the longer the piano wire the more weight you are adding, so short lengths are good. I make the bearing that the torque rod rotates and passes through, out of hardwood, not metal to save weight.

Cheers

Danny.

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