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Old Mar 01, 2014, 09:38 AM
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Originally Posted by killickb View Post
Eric, a bit of topic but I too am of the "spotter" age. Worked at both Farnborough and Thurleigh so saw all the latest jet age wonders. We used to bicycle to Wyton and get under the approach for Valiants, Victors and Canberras -- could feel and smell that kerosene ! Biked to Oakington and watched T-11 Vampires doing circuits all day. Biked to Alconbury and watched B-45 Tornados, T-38s, F-4's, KB50's. Biked to Waterbeach to watch Meteors and Javelins. Once, as 13 year olds we took photos of the new Hunter at Cranfield when we felt the hot breath of an Alsation on out necks at which time the guard took our cameras, unloaded the film and sent us on our way ! Where do kids go today, assuming the interest is there ?

If only Pontious would make plans for his large foamies. I have a Green-Air lightning and 104. Have a Vulcan, twin pusher and have seen some great Canberra models but never any commercial plans/kits, except by Golds. Jim Young has plans and short kit for a Meteor. I also received from Phil Smith, a few years ago, a new set of plans and a short kit for his Veron FD-2 which I laid out an R/C edf system ( I built a FF,diesel powered version many years ago, beautiful flier)

Remember --- "I love the smell of jet fuel in the morning"

Oh yes, to stay in thread, my Red/Yellow SV with CS-10 on 5 cell flies great, very scale in all aspects and though it does wag its tail a bit so what ! I don't seem to have half the problems stated in this thread or is it I just go fly?
We have a bunch of things in common - I forgot to mention that the excess fuel would "mist" down on you as they flew over your head. The sense of smell being the strongest recall! Due to the low level role, the local farmers had a field-day making claims against the RAF for crop damages :-)

Then there was the day I was arrested taking pictures and rode in a Land Rover with a pair of German Shepherds! Got a cup of tea and a beetroot sandwich out of that one! They trashed the film from my Brownie 128 - the box camera with a wire frame view finder. I think I was 11 or 12 years old and wearing short trousers and a beanie!. There is/was no fence on the peri-track at Scampton, just wide open oats-wheat-and- barley fields. Amazingly the Vulcans were carrying nukes! I had just changed the film and they never searched me for the one I had already removed from the Brownie. A super adventure to tell my pals at school - still have the B&W pics somewhere

I like my Vixens and have enjoyed experimenting with them. Looking forward to some serious flying this spring. Biggest challenge is the video making. I am sure we will see a meteor one day. For me, the V-bombers would all find a place in my hanger. I loved pulling my Vickers Valiant out on the slope and zipping back an forth. In those days (1970 something) the "slopers" were mainly polyhedral built-up wings etc. A fiber glass skinned foam wing was, and I quote many doubter, "Was never going to fly!" Now PSS is huge!

We can write all day about what we want - I wish there was "suggestion/demand" box instead of relying upon the whim of an employee in the far East.

I had five kids and they would never imagine biking the way we did. It was either stunt riding or "Dad I need to go to xxxxx".

Eric.

P.S. I started a "Hang-nail" blog to help me/us not hijack these threads :-)
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Old Mar 03, 2014, 03:38 AM
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Sorry again for "off topic"..Eric..That sounds like an old episode of "All our Yesterdays"..lol
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Old Mar 12, 2014, 01:06 AM
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Single exhaust

I have decided to convert my Sea Vixen into a "Single exhaust Racer".

The first reason was because I think the exhaust is tied in with the Waggle... the bifurcated exhaust. Possibly the exhaust enlarging (For CS use) causing a 'chaotic' exhaust flow, which then heads down the booms and to the tailplane.
That would also explain why some people have ZERO (??) waggle, but others X amount - varied.
Possibly lower, and higher, levels of power (within a flight), and also aircraft attitude and yaw per turns, could alter this flow and where it goes/hits.

So changing to a single exhaust will prove that....
It is half-useless as a 'scale' jet the way it is - even the Rudder gyros (or even if Aileron/Elevator added) cannot correct it properly. So it may as well become an over-powered 'racer' and test-bed.

If the single exhaust doesn't help, then I will trim the side pods down to FAW.1 type.

I also need about 40g more tail weight to balance it better. The stock CofG (which is where I balance mine) can't be right really, as it is extremely docile, with poor Elevator authority, and also needs quite a bit of Up trim to fly level = nose heavy.
Another 'fix' for that would be a tailplane incidence change.... but if I was going to do that then I would make it an all-moving tailplane as per the real one has - which would be an interesting/tricky project to do.

One way or another I will get it to fly "well"....
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Old Mar 12, 2014, 01:49 AM
It should fly at least once
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For the full flying tail I presume you could use a metal rod to hold the booms and to pivot the elevator using carbon fiber plates in the rear of the booms for the rod to bolt too. A wire in tube from wing mounted servo to operate it. Just thoughts I have not even opened my kit yet to check feasibility.
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Old Mar 12, 2014, 05:19 AM
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Interesting post PeterVrc in respect of the Cg location, I am in the process of building a Philp Noel Sea Vixen 1.5mm span and the Cg is a lot further forward than the Durafly model.
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Old Mar 12, 2014, 09:26 AM
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Originally Posted by PeterVRC View Post
The first reason was because I think the exhaust is tied in with the Waggle... the bifurcated exhaust. Possibly the exhaust enlarging (For CS use) causing a 'chaotic' exhaust flow, which then heads down the booms and to the tailplane.
Unlikely this is the cause IMHO. The waggle is present only when flying slowly or engine off like on landing. As throttle and speed increase, the waggle goes away. At least that how mine behaves

Looking forward to hearing how fast yours will go. Keep us posted

John
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Old Mar 12, 2014, 06:03 PM
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Actually, yes, even dead stick landing it is bad - possibly its worst, or equal to worst, time.
I was thinking the efflux might get 'cleaner' at higher powers (which then also happen to produce higher airspeeds too) but that landing process opposes that idea being right really....

But I will still make it a single exhaust anyway - I was investigating last night.....
I expect I can cut out a clean "block" right through the fuselage depth, from the rear of the fan housing and the width of the single thrust tube it will have. Then by separating (cutting) that block into "horizontal based shapes", I can use the top and bottom portions to fill in what can be done to flush it all back up... but still have all the pieces to restore the original design in future - not that I expect I really ever would.
One issue is the diameter.... the thrust tube would be much higher and lower than the fuselage shape - unless you made it a "squashed oval" shape somehow. Which would then add unknown efflux flow directions etc.... I guess testing round and "squashed oval" would be interesting to do.
The top an bottom 'flushing up' pieces, and tidying it all up and finishing it off, could be left off until it was all finalised anyway.

The all-moving tailplane is easy enough (simple really) to make the pivot system, the main issue I see is the load on the booms....
When there is an Elevator ON a Tailplane, as per stock, the tailplane and booms form a very strong (though even then not greatly strong) assembly that a small Elevator swings off. So it is all quite adequate in strength, non-twisting etc, terms.
If you have a whole moving tailplane, then the booms themselves have to support it rigidly each side by themselves.... two long items, made of just EPO.... and they are not that strong on their own - and now won't have that tailplane cross-join that creates strength when that far "out on a boom".
You could not use one servo, as that side would cause a twist across the booms. You would really need dual servos so they create equal loads on each boom. That is fine in weight terms... it needs rear weight anyway.
Maybe a pair of direct drive servos right into the pivot joint(?). They would need individual channels with curves created to TOTALLY equalise their motions! Eeek. (but easily enough done).
The booms would need a fair amount of re-inforcing - carbon fiber shafts, of adequate/decent diameters too. 5mm diameter at least.... which I have just the right thick walled 5mm for that. Meanwhile, those twin servos will struggle to fit into the boom(s) WITH a CF shaft down running down the boom too.... they would have to be int he "fin" portions - where some rudder servos already are on mine.
So... it needs a bit more investigation and thought.

If there was only ONE thing I was going to do, it would be the all-moving tailplane first! The stock pitch authority is woeful! If not dangerous!

The FAW.1 forwards boom portions.... that is a pretty easy mod in it plain physical terms - cutting away foam and re-finishing that. But it would need re-inforcing into the wing joint because of all that lost upper foam structure they give.
A full length carbon fiber shaft - needed for an all-moving tailplane anyway - would do that job. So those two mods go hand in hand nicely really.
The FAW.2 aspect (booms running all that way ahead) could even be the Waggle creator anyway - or part of.

I will probably start on the weekend, but even just the FAW.1 and all moving tailplane would take a 'week' or more.

I also have another mod I need to do somehow.... increase the internal ducting so that when I use larger batteries, which sit more rearwards, the total flow area is still large enough. As it is now, I lose a LOT of thrust if I use 3300mAH which need to go 40mm more rearwards, and thus block airflow too much.
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Old Mar 12, 2014, 06:14 PM
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I just had a thought !!
DennisP mentioning the CofG difference......
What if the stock Vixen CofG is way to far rearwards really.... and it is just not hyper-sensitive because of a reduced pitch authority (tailplane/elevator design).
Also, needing UP trim... which suggests nose heavy... BUT could just be because the Tailplane Incidence creates that.
That is only "nose heavy" IF the Wing and Tailplane design/Incidences are really correct in the first place.

So if the tailplane Incidence was made to be "right" (assuming it is that combination of it being "wrong" and CofG wrong) you could run a much more forwards CofG and still get good/correct(?) flight behaviour. AND maybe the wing/aerodynamic design HATES the stock CofG position and creates Waggle!
Maybe even the WINGS have a poor/detrimental Incidence setting.

If a CofG was MILES more forwards (unflyable, but say it was) the arm moment for it to Waggle off would be too 'long'. Meanwhile, if you have a very short arm moment then yawing is made easier and easier as it gets shorter. The arm moment is the distance from CofG to Centre Of Lift (CoL)... too far rearwards a CofG brings that distance closer together (shorter).

Some references to OTHER Vixens and their CofG positions would likely give a starting clue to all this....

This means the All Moving Tailplane is the FIRST mod to be done! Because it allows an automatic Tailplane Incidence change just from its own operation - being the whole tailplane able to move! And it will allow viable, flyable, large CofG changes to be tested.

So:
1) Check as many other Vixen CofG's as possible - to get some cross references
2) Change the Tailplane Incidence (many tests)... or change to an All Moving Tailplane, where just altering 'neutral' is a Tailplane Incidence change.
3) Test CofG moves more forwards.....

This seems a MUCH better sequence/process to follow - it could cure Waggle (improve it?), whilst also giving that full pitch authority fix, and might even give a good, great, better, flight envelope result too.
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Old Mar 12, 2014, 08:31 PM
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Just joined the Sea Vixon club. Anything I should know before the maiden? BTW, I have 2 Vampires.
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Old Mar 12, 2014, 08:40 PM
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It does fly well just as it comes... with CofG as per the manual.
So you should have no issues or fears for maidening it.

I would set it up for a LOT of Elevator travel, but have Dual Rates too. So use High for take-off and see how it goes for you, switch down to low to try that... then you will know what changes to make to those two rates.

Let us know it if "waggles" around - if it does it you will see it clearly.


---
Dennis... do have a pic of the PH Vixen CofG ??
FAW.1 or FAW.2? (should be the same CofG anyway really)
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Old Mar 12, 2014, 08:44 PM
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Originally Posted by PeterVRC View Post
It does fly well just as it comes... with CofG as per the manual.
So you should have no issues or fears for maidening it.

I would set it up for a LOT of Elevator travel, but have Dual Rates too. So use High for take-off and see how it goes for you, switch down to low to try that... then you will know what changes to make to those two rates.

Let us know it if "waggles" around - if it does it you will see it clearly.


---
Dennis... do have a pic of the PH Vixen CofG ??
FAW.1 or FAW.2? (should be the same CofG anyway really)
Thanks for the info. I do not have pic of the CofG
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Old Mar 12, 2014, 08:57 PM
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Thanks for the info. I do not have pic of the CofG
Looks like the front edge of the wheel wells should be the CofG?
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Old Mar 12, 2014, 11:03 PM
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Yes, even into the well.... but the edge is the manual's CofG point.
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Old Mar 12, 2014, 11:06 PM
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Gee that PND Vixen, and especially one that was made up in England to scale perfection(!!), looks awesome! Twin 70mm
The end of the thread has completed pics and flights.

http://www.rcmf.co.uk/4um/index.php/topic,94868.0.html

What a project!

This 'other' Sea Vixen scouring also lead me to find a few videos of PND and other scratch builts.... it is hard to SEE 10)% properly in videos, but none seem to waggle at all through their flights.
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Old Mar 12, 2014, 11:19 PM
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Agree with your comment "what a project", it sure is an awful lot of work but I have almost finished all the frame work of the fuselage. Hope to start the wings at the weekend and then tail fins and stabilizer. I have no rush and I only started it as I am waiting (3 weeks now AIYO..!) for a spare canopy for the DuraFly Vixen.

You can get a laser wood kit from Traplet but be prepared for a lot of balsa and wood bashing ha ha.
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