HK DH VAMPIRE 70mm EDF - Build Log - Page 6 - RC Groups
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Aug 23, 2012, 09:39 AM
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I like these as they have the 3mm locking screw size (in the bush ends). So you can use hidden grub screws then. BUT they cost a lot more than the HK ones. $11-50 Versus $6-99 !!

or these: (but out of stock for now... usually HK have stuff back in stock in a reasonable time frame)
These are a 2mm locking screws, thus need to use a hex bolt (preferably), that sticks out.
Sticking out makes an issue that you need your mounts to aloow for them to pass through to fit them. Not hard, but annoying.... and 2mm is not as strong as 3mmm!

I HATE the thought of $11-50 versus $6-99, but I MUCH prefer the PW-RC 3mm version!
They seem to be the same for the rest of the item construction and parts, but it is possible they are not. I am pretty sure it is the same company (PZ), but the HK ones COULD be requested to be 'cheaper' versions. So you MIGHT get what you pay for! LOL
I have both types in aricraft.... neither have failed so far.
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Aug 23, 2012, 09:55 AM
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Originally Posted by PeterVRC
I like these as they have the 3mm locking screw size (in the bush ends). So you can use hidden grub screws then. BUT they cost a lot more than the HK ones. $11-50 Versus $6-99 !!

or these: (but out of stock for now... usually HK have stuff back in stock in a reasonable time frame)
These are a 2mm locking screws, thus need to use a hex bolt (preferably), that sticks out.
Sticking out makes an issue that you need your mounts to aloow for them to pass through to fit them. Not hard, but annoying.... and 2mm is not as strong as 3mmm!

I HATE the thought of $11-50 versus $6-99, but I MUCH prefer the PW-RC 3mm version!
They seem to be the same for the rest of the item construction and parts, but it is possible they are not. I am pretty sure it is the same company (PZ), but the HK ones COULD be requested to be 'cheaper' versions. So you MIGHT get what you pay for! LOL
I have both types in aricraft.... neither have failed so far.
Thanks mate!
Aug 24, 2012, 07:53 AM
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flap installation

Well guys..My second try at fitting the flaps..I have beefed up the hinges and trial fitted a HK orange servo. The flaps fitted are a sandwich of balsa and glassed as the rest of the Vamp will be glassed..The hinges are home made from piano wire and thin metal tube epoxied into the foam The bridge in the boom will be filled. Im not sure if the HK servos will do the job. They are about same size as the Durafly ones used on the ailerones ..Advice from the readers on whats best would help before I glue them in..I may also put some .5mmx10mm carbon strip into the wings
Aug 24, 2012, 09:46 AM
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Flaps work is going slow..... slower than the flaps actually move! LOL
Getting the servo driven inboard flaps all done was easy. But working out HOW to interconnect the outboard flaps is causing delays - finding a good way to do that.
If only I had made the front edge of the flaps a "straight line"...... lol

Agediffers hinge system makes for a good way to also have the inboard an doutboard flaps connected!! So even re-doing mine in that sort of manner seems the best idea at the moment! But I will think a bit longer about it all.....
The other nicer thing I noted there was the inboard flaps being smaller and not reaching the trailing edge - I had not seen pics of the real ones, but if that is how they did it then that would be nicer to do. Easy enough to re-profile things, but I will leave that to think about more also.

I decided on using two position flaps. A low angle for take-offs (probably uinnecessary) and the severe 80deg angle for landing (more airbrakes than "flaps" really).
I put a TX delay function on the servo travel so that it is all quite slow - like real ones would be anyway - and thus allows pilot elevator trim, as required whilst they go down. Later I might mix in an elevator offset process on the TX too.
They are set for 6 seconds total travel time from retracted to fully extended.
The servos are each on their own channel so that the two sides can be finely tuned to match each other at all times through their motions - you can't do that on a pair that run of a Y cable. And they did need a fair amount of matching up, which I still did not get perfect yet. (no rush yet). It is not much fun having aircraft that "roll on flaps use"! hehe

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Last edited by PeterVRC; Aug 24, 2012 at 09:53 AM.
Aug 24, 2012, 02:13 PM
Making mischief in the air
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From a scale perspective - Agedflyer has the right look.
Hinge line of the flaps is a Straight line between both, the inner flaps dont extend to the trailing edge.

see here:

If your not so fussy about scale appearance you could leave as is and run 2 further servos.

Recutting to correct lines and using a bell crank to operate the inners has to be the way to go though ...
Aug 24, 2012, 09:27 PM
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Another issue is that the wings change dihedral at the boom, so there is still a kink in even a straight front edge implementation. But at least a kink in one direction is better than having TWO directions, like mine has!
Two makes it extremely difficult to fix up - it has to be via some "Sliding ball joint" system, which I rigged up to test but that can't transfer the strength required to the outboard flap. Not when small like is required to suit this.

Four servos is not viable. I would need to run all 4 on their own channels!! LOL
I can actually do that (I have 16channels) but it is a BIG WASTE of effort, hehe.

If I was doing it again I would mount the servos a bit more outwards and have the servo arm mid way IN the boom - cut out a whole boom chunk to replace portions after doing linkages to a centre horn between both flaps.
I guess I could still even do that really.....

Straight front edge flap pairing (not the stock Durafly moulding lines).... running off tube/rod with its bellcrank in that boom line.

Hmmm, yes, I will change it all to do that!!! That is just adding up as the truly perfect, and proper, way to do it all !! I just didn't think that the 'linking' would be very hard at all....
But for the moment I will leave it with just the inboard ones (outbooard taped up), so I can keep flying it for a bit longer first!
Aug 24, 2012, 09:39 PM
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Vamp flaps

Nice action Peter ...altho you lost me on the TX-Rx settings...Im not up to the electronics and need lots of help there..I have attached some pix I used for my inspiration..hope they help.
Aug 24, 2012, 09:45 PM
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Nice pics! The last pic seems to show the fully extended flap position. Or do they all??
In videos I have they are near vertical for landing!!
And then there is the next further outboard airbrake too..... (which I will not do)

I will redo mine in a week or two. I want to fly it!! Plus have a few other aircraft scheduled for things that are higher priority.
Aug 24, 2012, 10:30 PM
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TX programming:

By using an individual channel for the servos that means you get individual programming of each servo.

Whenever you have a pair of control surfaces (eg aileron, flap) you are highly unlikely to get all the geometries involved (horns, pushrods) dead equal on both sides. Generally if you try hard you can get a pretty good job done. But even the slightest deflection of a surface alters an aircraft's flight a measurable amount - and thus any difference from one pair of surfaces, to each other, makes a measurable imbalance in responses. (sometimes it can not be overly important, or as important, in "opposing action" surfaces, like a pair of ailerons)

Then there are variations in servos too. Their arm angle at 'centre' (1500uS pulse) position can be a bit different for two servos.
So if you have a common "Y" of the servos to one channel, you have no way to match up both sides perfectly.

If they are on their own channel you can set the endpoints, centrepoint, even the complete travel curve, to be perfectly equalise on both sides/surfaces. Thus you tune-up the servo pair, so that the two surfaces do everything perfectly identical.

Next, but not requiring individual servos, is travel timing and delays. If your TX has the ability, you can add in programming to alter the operation of servos, and even mix in various control inputs, and outputs, to produce a new sequence of servo action that you might desire or require.
In the case of Flaps, a slower timing process is useful. This can also be done with hardware - a servo slower, or a specifically designed 'slow' servo. But using those means it is permanent. Using TX functions means it can be altered, even enabled/disabled (eg by a switch) if you want.
So basically you set a time frame for the servo operation. eg I set 6 seconds for my flaps from retracted to fully extended. This allows the pilot to 'transparently' adjust the flight path to offset the effects of the flaps to the aircrafts AoA and 'new' flight path resultant of that. Imagine the severe change of attitude if it went to full flaps in a split second!! LOL

Then there is also the abiltiy to mix input/outputs across channels. So for flaps you would mix their position values into the elevator position, so it 'automagically' keeps the aircraft flying straight and true, whilst the flaps are extended and would otherwise alter the flight path. This is a tricky and finnicky balance to set up perfectly... but even 'just good' is better than no mixing help at all. The rest of the fine tuning you can do as a pilot.....
Aug 25, 2012, 07:29 PM
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A BIG success!!!

The Flaps are amazing!
I had gone out for a quick test at a lunchtime during the week, but it was very windy and buffetty, so whilst I got to test the flaps some amount, it was very short. Plus not to the full 80deg area angle.
They were already showing good promise then though.

But today I did extensive testing.....
6 seconds to full extension... that was actually a bit scarey, because I was worried that maybe something 'weird' could occur at the final huge angles and then it would take too long to 'reverse' that! eg ONE flap rips off.... or the plane goes ga-ga due to some dramtic lift issue occuring after 60deg. Who knows.

So the PLAN was to add an "Instant Retraction" mix to a switch - in case such a disaster occured! To get them back in FAST.
But I forgot.....
I was supposed to set that all up in advance at home.... sigh.

So I had the taped up outboard flaps, and full 80deg inboards. And about 25 deg for "take-off" setting.

In flight... slow down, so as not to rip them off! And the Level1 25deg did almost nothing perceivable. They probably DID do domething, but just too hard to measure by sight.
"Click' for full flaps.... at about 15metres height.... be ready for anything!!!

Nothing untoward happened at all. The Vampire slowed right down to a crawl.... but didn't even change AoA or anything!!
This is a 6 second process, moving to greater and great angle... and it just did that with no side-effect!

I did a circuit.. and that means about 50metes diameter!! At near walking pace. Probably about 30% throttle area (not that the % means anything specific really). And I just cruised on past at about 3 metres height, to check they were down properly... and they were.
All I could think was "WOW!!!!"

Massive slow down. No attitude effect!
A perfect result.

So I cycled them a few times, going back to full WOT speed, and then down again. That was the main worry..... what speed could they cope with safely?
I just dropped to the 30% throttle area, waited a bit until it visually looked ok - but that was still 'fast' really, seeing the Vampire never wants to slow down much really - then went to Flap1 first. Then Full Flap soon after.
I think what happens is that the 6 secoinds it takes is a good enough delay process that as the flaps angle increases, the speed is already falling adequately thanks to them, for the further angle increases. eg If you had instant full angle... they would surely rip off I expect!
So even the timing sequence was perfect.....

I reckon it was flying at something like 10kph, to 20kph max. EXTREMELY SLOW. And dead level !!! Not some huge AoA etc. Maybe it was +5deg... but whatever it was it was minor and not enough to even tell whilst concentrating on the flying dangers!

I flew 10 flights. The first landing with full flaps. Which I have to switch off when it is still 30metres out approx, so that they will be at least halfway in before any touchdown. Seeing I have no landing gear!
The next landing, with no flaps, was an eye-opener of the huge extra glide time it had. That psycho glide ratio amazes me every flight! LOL
So back to flaps landings.... then later another no flaps.....

I would guesstimate the difference is FIVE to one! Five times shorter with flaps. And that is using about 30% power, versus no flaps being full engine off to TRY to get it to the ground as soon as you can!
It is so short, that if you want to use all that ability it is unrealistic! Too slow a landing speed.
But that can be adjusted to be realistic by POWER... just like real aircraft do land with. I could not test and fine tune that, because without landing gear it is all too demanding already - needing to retract flaps before touchddown etc. So you really want to work out all the 'realistic landing' stuff when it has landing gear and the flaps stay down the WHOLE way.

But all in all. PERFECT. Exactly as desired and needed.
Mind you that is only on inboard flaps - which mine are a little bit too large anyway.
I expect adjusting them to scale, and having outboards, the angle used then could be from 70deg to 80deg.... I guess a higher angle just means more throttle maintained through the landing.

I will adjust the flaps to scale.... but I don't think I will add the outboard ones at all, unless I get more enthusiastic. The main mission goal has been achieved..."A decent... proper, realistic.... landing process Vampire" !!

Mind you, I am also flying at 1380g AUW area. But it doesn't even notice that. It is still way too manouverable. And still just flies off out of my hand with the slightest of pushes. The massive lift it has means even 20kph is enough speed to be 'flying' already.

I have to work out how to get flight videos done!
The Vampire is a very suited size, and flight area of operation, to my main park area. It can be kept within a few hundred metres (150? 250?) whilst still flying scale speeds and turns etc.
And it looks awesome, because that means you get to keep the trees etc in the background, which give a good total picture and atmosphere to it.
Last edited by PeterVRC; Aug 25, 2012 at 07:35 PM.
Aug 26, 2012, 04:24 AM
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That is a very good report Peter..What would happen if you had both flaps working and only gave them 50% (1/2 flap)? I am only new to this having NOT even flown. I'm an aged flier hence the I'm trialing just with the basic HK -T6A V2 and will use the VR knob to "dial in " the amount of flap..Where do you fly?? maybe you can be my or buddy me..Any help setting this one dialed into the HK would help me a lot...I have retracts..
Aug 26, 2012, 07:31 AM
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Aged, you don't show your location.

Seeing I didn't do it via pot, I don't know what various angles will do for sure.
At the lower angles, they will work like flaps. And I expect they would 'crossover' out of that 'normal' aerodynamic operation once they get too large an angle. Becoming airbrakes more than flaps. Plus we have the interesting effects of split flaps, versus full piece flaps - which again have a different aerodynamic effect.
Split flaps leave the top surface camber intact... and thus create some 'warped' new total of top camber normal, lower camber (not far off flat normally) severely altered.

Pots are also hard to replicate angles well whilst flying. I would set it to move them from retracted, to full pot being just the max you want to be able to get to (the 80deg area). To make the position guaranteed.
Having 80deg means a large portion is airbrake. At 50% it is probably half-half flap and airbrake. So I think we really need large angle, because we certainly DON'T want more lift!!
The real one probably does need some amount of lift increase also... but we don't!!
So even if the real ones only do 60deg, we still want more angle really.

So having two pairs of flaps (inboard and outboard), could make that tricky. Because you still need the same angles really - to pass beyond 'flaps lift' region - but then will have much larger 'airbraking' due to the larger total area presented.
It would need to be tested - but at a guess I doubt it would be so much as to cause any huge problem, or crash. I expect it would just need some more power to offset it, and that should be fine.

So like I said... I would set the pot for 0 to be retracted (of course) and 100% to be the full flaps 80deg area angle. And just turn from 0 to 100% at some rate of 4 to 8 seconds I guess.
Not instant, as you want the drag to build and slow the plane, so that by 80deg they aren't going to be ripped off! LOL

If I didn't know that mine went all the way to full flaps without any flight detriment at all, I would be scared to head gradually down to full, via a pot. Twiddling that whilst not being able to focus, and control, all sticks normally. hehe. But it seems they have no detriment for some reason, thus yours should be the same and as long as you have the pot opposing the elevator stick it should be fine. (or you might have side sliders?).

I was scared! LOL. Even with a switch - but that was part because it takes 6 seconds... and also that long to get them back in IF things went to crap when they headed down! Because it would probably be in the ground before that!
So the first time I was fairly high, held my breath and just went 'flip' (switch)! hehe
And all was TOTALLY fine.... surprisingly.
Aug 26, 2012, 07:45 AM
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T6A ?? Texan?

The Vampire is sort of a pussycat.... very well mannered. But I would call it a 'scalded pussycat'!! LOL. Because mine is fast, and you can also "feel" the mass of it, so pretty much like a real one (or any real plane) you would not want to crash it! LOL
Easy to fly... but even 1100mm is not a very small plane, and more so when 130kph capable!

I am trying to get someone - and more importantly a usable camera - to video it. It is very impressive to watch, and hear! But useless to make some lame video that doesn't capture it all properly. There are planty of others to watch if you only want to see "a Vampire flying".
Aug 27, 2012, 05:42 AM
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Peter I am from Bendigo and have family I visit that live at Lynbrook just out of Cranbourne.. It sounds like you are wanting someone to video your vampire from the ground?? I have bought a cheap HK keychain cam that seems to give good "onboard" results. I have seen a clip where someone attached a keychain cam to the middle between the fins.I might just make dummy cockpit and try that should be an easy make from foam and ply. I haven't been able to relocate it again. It might be in the other vampire log so will look again..but its over 1000
Aug 27, 2012, 07:43 AM
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I have the HK keychain one too - prob the same one. Plus the WingCam one.
They are pretty lousy - ok for on a plane, sort of.
I have a Sony handycam, and also a digital SLR that does video too, which of course both are far better but even with a 'good' camera it is a tough job making a good video of model aircraft! LOL. It pretty well needs someone with either experience, or a fair bit of effort to 'learn', how to film flying models appropriately. Tracking/panning.... focus.... zoom.... it is actually not easy to get everything nice and right.

My partner's parents live in Bendigo (Golden Square), so we go every 4 to 6 weeks or so. I have been to the aero club up there that fly out at Marong.
I myself am in the Northern suburbs, off the ring road.

I will start retracts this week. But it is such a great hand-launcher!! I really don't want to even bother with retracts... but if you want to take-off and land realistically, what can you do! LOL
I can still throw it then anyway..... hehe
It will hit 1500g by then I am pretty sure. Which is fine.
I was checking my 1200mm Spitfire yesterday and it is 1700g!!! And it flies fantastically - even still a bit light. They are typically 1200g to 1300g.... or at least that is what 'they' advise, and most people strive for - but that is just ludicrously light.

I will do the retracts to operate the 'right' way - not as per the stock ones (wrong direction).
Hmmmm, maybe I better do the inboard flaps re-shaping first, and fill out the trailing edge for those. Then plan the retracts for after that. The outboard flaps.... I don't know what I will do about them yet.
And NOW I just realised what they need....... the servo mounted further outwards with the servo horn IN the boom and then DUAL pushrods!! DOH!! (the light bulb just popped on....)

For the retracts I will use suspension oleo's too. Not just wire legs.
I won't paint, repaint, it all until it is all completed. It still looks great in the air just as it is for now anyway!

Bound to be some way we can plan to meet up! What sort of place are you flying at now? Park? Field? CLub?
I also have a few TXes and can buddy them up easily. I am not fussed to let someone fly a plane that way (mine).
Last edited by PeterVRC; Aug 27, 2012 at 07:48 AM.

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