Durafly EDF Vampire

[Ian Jones]

Thanks Piers (hope you have dried off) & Graeme, all information greatly appreciated.

Rather more windy at our field than I had expected none the less I judged that it was not too windy, so went ahead with the maiden flight. A few things cropped up but it was a successful flight.

The strip was in the process of being mowed so the presence of damp cuttings was a bit of a concern, however it was only half mown for some reason and I elected to take off in the uncut area. That involved quite a long take-off run but when it did break free of the ground it rose sharply - needed 18 clicks of down trim and no aileron trim. A very slightly clumsy landing removed one of the main undercarriage legs from it's housing and my belief that my landing hadn't been that bad was confirmed when I found that very little of the adhesive that attached the undercarriage block to the wing had actually been in contact with the wing. UHU Por changed all that.

For the second flight I went for 12 mm movement 10% expo on the ailerons, 10mm movement and 10% expo on the elevator. This worked well and I will use this as my "safe" setup and take everything else from there. The strip had been fully cut by then and take-off was a doddle. For the CG I settled on a compromise between the instructions and various suggestions at 305mm though I will try Piers's 290 mm as I think this will help with the power off glide and also the landing which was rather floaty. An examination of the fan afterwards did not show any injestion of cut grass, though these was some around the air intakes under the fuselage.

I would have had a third flight but I'd forgotten to put the first battery on charge after leaving it to cool down (it wasn't hot - just warm).

On a calmer day it may perform better but I have to say it was somewhat disappointing but then I have something to measure against; a TN Vampire with an SC25 on the front - the durafly version can't touch it performance wise. In addition with the TN Vampire I can fly all day on a just a little fuel whenever the moment takes me. The performance is fantastic and no inconvenient waiting for batteries to charge.

Edited By Ian Jones on 02/09/2012 20:27:54

[Capt Kremen]

Congrats Ian on the successful first outing

The more forward C of G seems a fairly common adjustment.

Ian & Piers - Did either of you experience the power on/off - pitch up/down that I've read other 'Vampire' jet-jockeys have encountered?

i.e. Power off, it pitchs up so you add power and a touch of down and it pitchs too much down.

This has been suggested to be either the power-on 'jet' thrust striking the tailplane which itself may me at a less than ideal incidence to the main-wings.

My 'Vamp' build is struggling, trying to check the balance of the fan on a supposedly top-notch magnetic prop balancer from the 'good 'ol US of A' ... Hmmm ...

CK

[Ian Jones]

Thanks CK.

I did get some power off pitching up. Seems like thrust line but could be a little tail heavy which would show more at low speed. More flights needed to check that out.

Mine is the PNF version so the fan should be balanced.

Ian

[Ian Jones]

Right, half a dozen or so flights completed now so time for an update.

First off there's the modifications that many of us have found necessary to ensure survival of the aircraft and lesser modifications to make it work as intended (my list will follow shortly). That so many people have been in this situation means to me that:

• It's not up to the claim to be PNF
• It's not suitable for the unwary/inexperienced flier.

Let's have some positives anyway:

• Sounds great especially the jet blast.
• The retracts actually work (touch wood). I have found myself at the controls of several foamies with retracts that have failed to operate correctly. I've managed to save the aeroplanes but it's not want we want on a regular basis. So if the Vampire retracts continue to perorm then that's a big credit.
• Looks good with a good stand-off scale representation of the Vampire FB6. (Yes I do know that XH292 was a DH115 Vampire T11)
• Handy size. Just fits in the boot of my car without putting the seats down
• Flies well (if sometimes a little strange - see power off comments later)
• Takes off from grass
• Hand launches easily
• Lands well on it's wheels or belly.
• Difficult to stall
• Reasonable speed
• I've not experienced any overheating of the LiPo or ESC
• Relatively cheap, a little over £100 for aircraft and two 2200 batteries. I already had a receiver.
• I'm starting to like it (I'm not a fan of foamies)

A few minor concerns:

• Ingestion of grass via under fuselage air intakes. Cuttings from when the strip has been cut are sucked up easily.
• Power off floating. I've set a flight condition on my Tx which puts in some down elevator for power off flying as well as moving the CG forward. I'm considering opening the throttle trim to a slow idle before taking off (without affecting the failsafe) to see if the resulting airflow will prevent the pitch change.
• Quite noisy
• Pilot needs a booster seat to see out of the cockpit
• Aileron horn screws too short. Reports show that this has been a problem for some time - why let it happen in the first place and why allow it to continue!!
• Mine has foam wheels, not rubber.
• Only getting about 6 minutes flight times on Gens Ace 2200 batteries. I could extend the time by not doing any aerobatics!
• Working on it I've made finger nail marks all over the place
• The silver paint easily rubs off.

More importantly:

• As previously mentioned the booms needed reinforcing
• Right undercarriage leg came off on the first landing due to the most of the glue on the leg block not having contacted the bottom of the housing in the wing. In other words there wasn't much holding it on.
• No keepers on the clevises, I had to add them:

• Tyre wall rubbing on the undercarriage legs causing erratic steering, I fixed this with some servo discs:

• Steering wires poorly crimped and slipped so I replaced them (photo is before not after ):

So what now then?

Well if after all the above I have a reliable, interesting if not terribly exciting aircraft then I suppose for the money I've done alright and I'll continue to fly it with increasing confidence and pleasure. If not then it will be a long time before I buy another foam or electric aeroplane. Either way, being unimpressed with the Hobby King web site I'll be avoiding that if at all possible.

Edited By Ian Jones on 05/09/2012 01:14:49

Edited By Ian Jones on 05/09/2012 01:18:57

[Dean B]

I bought a hobbyking Vampire at the beginning of the summer ( what summer is that then)?. It screams like a banshee but once in the air sounds quite realistic, I fly from a grass field so the retracts are redundant. Belly flop onto the grass but make sure the motor is off or it will suck up debris and spit it out of the back. I have had a few mishaps with it, the tail booms have been repaired several times. I eventually managed to fit some carbon fibre rod all the way down the boom to strengthen it. Very exciting to fly although it can be a bit twitchy at times. Only runs for 41/2 mins on a 2650mah 50C nanotech lipo.

[Ian Jones]

My Gens Ace Lipos are rated at the recommended 25C, perhaps the ESC can pull more power out of the 50C LiPo and give more speed for less time?

If anyone wants to you can now submit a review here.

[Reno Racer]

Anyone know if you can buy CNC parts for the TN Vampire kit (Westfield)?

chris

[Ian Jones]

Posted by Christian Ackroyd on 05/09/2012 13:44:42:

Anyone know if you can buy CNC parts for the TN Vampire kit (Westfield)?

chris

No, sorry, but the plan is still available and it's a really easy build.

[Ian Jones]

I am not happy and I take back anything I have said that might encourage anyone to buy one of these.

My previous comment ".... if after all the above I have a reliable, interesting if not terribly exciting aircraft then I suppose for the money I've done alright and I'll continue to fly it with increasing confidence and pleasure." is really annoying me.

I'll tell you why.

I predicted that this evening would go really calm about 7pm. It did.

I had decided to try raising the throttle trim before take off so that the fan was just turning at it's very minimun amount when the throttle was fully down as this might help the glide. It did.

I decided to go for the best landing ever, really low approach, really low speed, gentle flare onto mains and then the nose wheel. I did.

That was flight number 7.

Now feeling really confident that the aeroplane performed as it should I was thinking about how great it will be to show it off on our club open day on Sunday. So I strapped in another battery placed the vampire on the strip and down went the noseleg.

The noseleg retract was dead. Where is it all going to end? One problem after another is never good value for money no matter how cheap something is. Seems this something was just too cheap!

Going to take this up with Hobby King now.

[graeme jones]

Ian - best of luck with Hobbyking, I'm still waiting to hear from them about my blown ESC which was posted back to them 10 days ago.

Graeme

[Ian Jones]

Thanks Graeme but it looks like being a hard slog. They asked for video evidence so I made a short video starring an unshaven you know who and the troublesome vampire. During the making of the video another retract went u/s. I sent the video to the email address they provided and got a quick reply - send us photo/video evidence so I sent it again. I bet your beginning to guess what happened next?

So I sent it a third time adding:

"Since you keep losing it I have now uploaded to:

Link to hobby king videos

and

YouTube"

 

So I might as well post the YouTube video here:

 

(ooh couldn't get Youtube to embed - use the link above)

These are just facts - I'm not making any premature judgements.

I hope you are sorted out soon too Graeme.

Edited By Ian Jones on 08/09/2012 10:30:48

Edited By Ian Jones on 08/09/2012 10:31:32

[Tom Wright 2]

[Ian Jones]

Thanks Tom. I've embedded Youtube videos lots of times but it just wouldn't work in the last post.

[Piers Bowlan]

Ian, I purchased the ARF version of the Durafly Vampire because the field I use necessitates hand launching and a belly landing. Your woes with this model all seem to stem from the landing gear; wheels that bind, retracts that don't, grass that gets sucked into the fan etc. Like you said the entire model cost you a hundred quid including a couple of LiPos. Considering how cheaply the Chinese toy trade turn out these models (in their thousands) and what Durafly no doubt pay their suppliers for the landing gear sets, do you think it very realistic that they are reliable? Fit for purpose? Probably not.

The wheels are tiny in comparison to even a landing strip as smooth as a putting-green. For scale, think of a full sized Vampire landing in a field of elephant grass -messy! The stresses on the landing gear attached as it is to EPO (even with a gentle touchdown), are enormous. My advise is to ditch the landing gear (the model will be lighter/fly better without it) and enjoy the model for what it is; a fun, foamy, Scale-ish, model that you can bung in the back of the car. You will be able to use a bigger battery too because of the weight savings = longer flight times to boot.

Still good value in my book. Just my 2p worth!

[Tom Wright 2]

My thoughts entirely Piers.And certainly a good buy as airframe only .A fixed u/c with decent size wheels will also work well as the foam will take the loads easily if the mounts are designed to spread the load.

Don't give up on it Ian I recon you could still have loads of good flying with this model.

Tom.

[Piers Bowlan]

Big wheels look OK on a Cub but would probably spoil the effect on the Vampire not to mention have an adverse effect on performance. For me it is all about the flying qualities and a landing gear only adds complication, frustration, drag and weight with a model of this size. But each to their own.

[graeme jones]

I fly off grass too, so I took the retracts out and taped over the openings, except for a bit in the main wells to use as grips. Hand launches easily at about half power because of the light weight and goes like a train. I would have taken the fan out to balance it, but an excess of glue at the factory (a common fault with HK ARTF's) prevented that so it is noisy and I expect the fan or motor will eventually fail. The cure for sucking up grass clippings is easy - use a mower that collects it all. HK wanted "video evidence" of my speed controller blowing, but I told them I didn't have a time machine so they would have to settle for photo's of the burnt/melted components. They agreed but I'm still waiting for a replacement or credit to buy one.

Graeme

[Tomtom39]

I have ended up with the HK Durafly Vampire or rather it came as a large jigsaw puzzle in a plastic bag - another members left over. I decided to proceed with repair . I have used some lightweight kevlar cloth and tow to repair the broken booms as well as adding some CF 2mm rod along each length. I replaced the rather "poor" fan unit with the E-flite 15 from my spare Habu inc 60Amp E-flite Esc. I covered the whole model with lightweight GF cloth and used four coats of Poly C website **LINK** . I have ditched the retracts as they were far to damaged to repair - shame as they did look nice ( the nose wheel and one of the wing retracts had given up on landing with its previous owner )- wonder if one of the FMS units will fit into this?

The plane - a little heavier than before (inc squeezing in a 3000 Mah 4S has flown very well ) . It did have a tendency to pitch up on powering up in flight . However have cured this by rejigging the tail (elevator stab) with some negative incidence approx 2 deg's. Another club member very kindly offered their undamaged unit as a point of reference.

Deluxe materials also sell a similar product to the waterbased varnish from Poly C

[Ian Jones]

All points taken and the main one being that out of the box it tends not to be as it should and modification is often required.

However, I already have a vampire to hand launch, the great attraction with this one was that it can take-off from grass, as wintnessed by numerous YouTube videos. Another point is that the model is made of mostly run of the mill stuff that isn't very expensive so there is scope in the production costs for retracts that work and work they will.

HK are looking into the matter and it would be prejudicial for me comment any further on that at this stage.

By the way, this is what a real FB6 looks like.

Edited By Ian Jones on 13/09/2012 01:00:31

[Piers Bowlan]

Yes it is all very frustrating Ian, when the build quality of the BNF is not what it should be. I would be prepared to pay a bit more for a product that is better engineered. A pity Multiplex have not got into the 'scale' market as I have been very impressed with their well sorted foam models even if they are a bit pricey.

I did a 30min flight one evening, slope soaring my HK Vampire in 15-20 knots near my home. I only used 700mA from the 3200mAh LiPo and that was for the initial launch plus a couple of obligatory low strafing runs along the ridge! The sun was setting and the slope was deserted, very atmospheric! My 'arrival' was rather untidy as a wing caught a tuft of grass, the wind sending the model cart wheeling down-wind. The tail and booms duly parted company - it was only a matter of time as there is little strength in them. After I reassembled the 'kit' and cyanoed two 10mm wide reinforcing carbon strips into slots cut in each boom I could not believe how rigid they had become. You would think that Durafly would include these in the kit as it only took a few minutes to do and added only 15g.

Thanks for the picture of the FB6 Ian, I have been looking for a suitable new colour scheme as my Vampire is looking a bit battered and could do with some mid-lifeTLC (filler!). I may go for the Swedish olive green scheme just to be different.

[Tomtom39]

Having had the pleasure of the Durafly Vampire . I managed to fly one of these today **LINK** Costs more than three times as much as the HK one but it really is a case of getting what you pay for. (I have just taken the decision to order one - there is a waiting list!)

[Tom Wright 2]

Wow a 1.5 m span fomie for £320! .......It must very very very good indeed.

[Tomtom39]

I have to say that my first impression on finding how much the model cost was exactly the same ie £320 for a fomie!- on your bike - however having flown it (in both light and heavy breezes). I would have to say that this model is the proverbial peach (note this is the Venom and not the Vampire). It oozes quality - both in looks and handling.

[Garbo]

Posted by Tomtom39 on 13/09/2012 22:26:09:

I have to say that my first impression on finding how much the model cost was exactly the same ie £320 for a fomie!- on your bike - however having flown it (in both light and heavy breezes). I would have to say that this model is the proverbial peach (note this is the Venom and not the Vampire). It oozes quality - both in looks and handling.

Oozes quality and haemorrhages cash

[Tomtom39]

Garbo.

Very good and very appropriate!!! Lets just say I fell in love with it. A treat to myself having splashed out on a new handbag for the wife over the weekend - so don't feel toooooo guilty.