Topic: Fairey Delta 2 70mm EDF build

Bloody hell Dizz! that looks great!!

I'm flatterd again Jamie.  I don't know why, but I'm still a little wary of doing that though.  Maybe it is because this one (actually all of them) have a few unconventional/unorthodox design aspects and use somewhat exotic power trains.  I’m probably in a position to produce a short kit and a very basic plan now, but probably best to wait until it flies.  That could only be 2 weeks away (makes a change from the previous 18 month gap from completion to first flight!).  However I am popping into Stan's today and will discuss costs, etc with him – I think it might work out that you wouldn’t get much for your money though so be prepared for a shock.
Pete

Speaking purely for myself here, I wouldn't be expecting a flashy box and shiny illustrated instruction book. If you made a copy of your parts available to me I'd think of it as just that - so if it doesn't fly as well as the Phase 3 EF16 then fine. It's a bit different and unusual. That's the appeal. I can fettle and fit balsa. I could build the whole thing from scratch if I felt so inclined, but as you've already invested some effort I would merely regard some of your parts as a head start on an otherwise traditional scratch build

Speaking purely for myself here, I wouldn't be expecting a flashy box and shiny illustrated instruction book. If you made a copy of your parts available to me I'd think of it as just that - so if it doesn't fly as well as the Phase 3 EF16 then fine. It's a bit different and unusual. That's the appeal. I can fettle and fit balsa. I could build the whole thing from scratch if I felt so inclined, but as you've already invested some effort I would merely regard some of your parts as a head start on an otherwise traditional scratch build

Gotcha 
Actually someone like you Jamie wouldn't have any problems with this.  Where you wanted to adjust to fit your own requirments you could send me the amended part details and I could easily CNC some new bits.  I'll PM you this afternoon when I get back.
Pete

Bloody hell Dizz! that looks great!!

Just imagine 2 of them flying together - one magenta and one blue, one with a P60 and one with a Stumax 110.   
Are you thinking about doing a day at M'F next week?
Call you later

Looks great Dizz. It looks like its going mach 1 just resting there.

Geoff.

Speaking purely for myself here, I wouldn't be expecting a flashy box and shiny illustrated instruction book. If you made a copy of your parts available to me I'd think of it as just that - so if it doesn't fly as well as the Phase 3 EF16 then fine. It's a bit different and unusual. That's the appeal. I can fettle and fit balsa. I could build the whole thing from scratch if I felt so inclined, but as you've already invested some effort I would merely regard some of your parts as a head start on an otherwise traditional scratch build

Well while you've got the cutter running you might as well do 2 lots 

To be honest, unlike Jamie and yourself, I dont have the skills to build one from scratch but i'm pretty sure I could with a set of parts 

Elevons glued on with Hysol over 2 days.  Servo plugs fitted this afternoon then the servos fitted and controls set up.  I’m have used the same reflex (~2mm outboard end of elevon)), throws, expo and dual rates that the P1091 has, so first flight shouldn’t be such a leap into the unknown.  I am going to wait until it has flown before fitting the control rod covers in case any mechanical adjustment is required.  After the previous servo snag I have paid particular attention to the elevon centring this time and with these digital servos it is spot-on.  BTW, exercising the P1091 suspect servo for 90 minutes has cured the poor centring, but whilst measuring the throws to transfer to the FD2 I noticed that the throws were not equal or in sync.  Hopefully that will make it much less of a handful in roll – it will be going to Abingdon too.
 
Anyay, the FD2 calculated C of G is between 295mm and 305mm from the TE(=17-20%MAC).  The P1091 was initially set up for a C of G 335-348mm from the TE (20-17%MAC) and first flight was at the forward mark.  However following Geoff’s and Jamie’s flying experience of the P1091 and their recommendations the C of G has ended up at 332mm from the TE (20.8%MAC).  Now I’m thinking that the long nose on the FD2 will generate significant lift and have a big effect on Cp, so therefore I am fitting the battery to achieve a C of G at the forward position, or even a few mm further forward than that. 
Thoughts anyone?  Would appreciate the input thanks.

Full power test day tomorrow 

Well that was rather exciting - seems to be getting a habit!  First pack (brand new, only been used once to set up the throws yesterday) was just warming up then decided to give up.      Swiftly removed to the back garden to burn out.  Now I have looked at it I think there was a fault on the small bit of PCB the cells are soldered too – maybe it got dropped/damaged.  Anyway, good job it wasn’t in flight or even on the ground about to be launched.

Final empty all up weight is 1726g (inc some Velcro and the control rod covers yet to be glued on).  Never mind, I’ll continue to try and build (finish) lighter with the next one.  It must have been colder today because you could hear the batteries delivering more as they warmed up under load.  In the “flying condition” nose down on the scales and steady state running 1 minute after opening the throttle I got 1970g (19.2N) static thrust, 1850W, T:W=1.14 and efflux velocity of 201 mph (89.9m/s).  Based on those figures I have a theoretical S&L speed in mind (it is rather high  ), but will see what I get from Doppler when it flies………………………………roll on Classic Jets 49 at Abingdon 30 December!

Still looking for some comment on C of G position please.


The big Viggen should be next, but I just remembered that I have a P1154 wing already cut, the fuselage is 70% drawn and I'm using the CNC machines all day on Tuesday 

That thrust to weight ratio sounds like fun 

What make of LiPo was that out of curiosity?

I haven't really got anything to offer on CofG though, but since there's washout in it I might be tempted to move the test flight CofG forward a bit from your calculated and just make sure there's plenty elevon movement for pitch authority. It can only fly sluggishly that way 

Swiftly removed to the back garden to burn out.

For just that eventuality I have a powder fire extinguisher clipped to the shed wall. Just 17 quid from B&Q.  I hope I never have to use it - but if I do, I'll be fekkin' glad I bought it 

Never, ever, turn your back on a LiPo

It isn't going to hang around, that is for sure!
The battery "was" a Zippy 3000 40C 6S.  The other 2 packs have performed well so far, much better than the 2 Turginy 3300 30C jobs I bought for the P1121.  I'll see what is on offer in the same 3000/40C category in the New Year.
Thanks for that - I'll mark up some C of G positions tonight and then we can set it on the day.

For just that eventuality I have a powder fire extinguisher clipped to the shed wall. Just 17 quid from B&Q.  I hope I never have to use it - but if I do, I'll be fekkin' glad I bought it 

Not sure an extinguisher would help as I believe Lipo fires are self-sustaining once they get going - guess it could put out any secondary fires though 

Hey Dizz,

As you say, it is going to be rapid.  Looking forward to the 30th.

Geoff.

I was at long Marston today to witness the test flight of Shane Hardings EDF Hunter. It is a similar size to the Mick reeves one but all built up wood construction. It has the same Stumax fan as Dizz has and 12S battery set up, it flew really well and a video will be put on Youtube tomorrow.

I am not the biggest fan (no pun intended) of big EDF power but i did get my first go on a HP EDF model in the shape of Shane Hardings F15 and as much as i hate to say it . . . . . i quite liked it! it flew very well and had a fair amount of grunt! as with all Avonds F15's, it was so easy to land and even easier to fly.

I have to admit to being quite surprised with the performance . . . . . . . this does not mean i will be running out and buying sandles, a tank top along with a big EDF model !

12 days and counting Geoff 

Nice colour scheme, how heavy is it Jamie?  I'll be running the Viggen on 12S too.  Unexpected visitors this afternoon so didn't get around to firing it up today, but will do tomorrow -  Fire Brigade informed.  What are you doing Wednesday?  I could pop up with your canopy if you are free.
Am off to polish my sandals now, will call again tomorrow.


PS
Accidentally glued some P1154 tail plane and fin bits together this evening - doesn't make me a bad man though, I just need help

Thats good! i cant even spell sandals!!

Come on up, will be in all day . . . . in the workshop.

Shane said Hunter is 15/16 pounds.

Dizz I am sure you have read this but in case you haven't
CG of models in this one
http://aerade.cranfield.ac.uk/ara/arc/rm/3738.pdf

Moments and inertia
http://aerade.cranfield.ac.uk/ara/arc/rm/3620.pdf

As yours is going to clip along at 150mph
http://aerade.cranfield.ac.uk/ara/arc/cp/0672.pdf

And just because it is interesting well to me anyway
http://aerade.cranfield.ac.uk/ara/arc/rm/3582.pdf

That's good! i cant even spell sandals!!

Come on up, will be in all day . . . . in the workshop.

Shane said Hunter is 15/16 pounds.

Will do in that case.  I'll weigh all the Viggen bits this afternoon see what the total is so far  and make an estimate.

No I hadn't read any of those.  Great links thanks, very interesting indeed - mine is approx 1:14 scale. BTW, they actually flew the FD2 supersonic before alot of the high speed wind tunnel testing had been started.  I have based my calculations on a couple of other aerodynamic texts and formulae.
 

Dizz,

You need to get on with some small turbine model design action! P20 is looking for a new home and it needs something different! Got something new to show you wednesday . . . you will love it! . . . . and no i wont consider HP EDF for it!

I am thinking Vixen? Scimitar? Vampire? Sea Venom, Hunter? Attacker? or a slightly bigger FD2?

The real FD2 had a C of G at ~31%MAC and a centre of pressure at ~ 67%MAC, so from that I conclude that Fairey didn't make any significant allowance for the forward fuselage/nose.  The first time we tried to fly my SR177 the C of G was at 30% MAC, but that was way off and I subsequently discovered that model deltas tend to have a C of G about the 20% mark.  It would appear at the dimensions and speeds we play the forebody does have an effect.  Anyway, I decided not to alter my calculations based on that, but Fairey also didn't allow for the slight change in LE angle at the outboard edge of the intakes when defining their centre line chord - I had. 
I have re-calculated my C of G and I now get a 17-20% range at 298-310mm ahead of the TE.  Battery has been adjusted to achieve a 305mm position and I'm  happy with that.
The real one had the ailerons rigged up at 2.3^o and flew trimmed to between 3.2^o and 4.2^o up - mine is rigged at 2.8^o up and won't fly as fast as the real one, so again I'm happy with the reflex as a starting point.


I find it mildly amusing that I have used 30+ year old technical papers on the real aircraft to help with a semi-scale model.

Dizz,

You need to get on with some small turbine model design action! P20 is looking for a new home and it needs something different! Got something new to show you wednesday . . . you will love it! . . . . and no i wont consider HP EDF for it!

I am thinking Vixen? Scimitar? Vampire? Sea Venom, Hunter? Attacker? or a slightly bigger FD2?

You have got me thinking what POS you have bought now


A Hunter or bigger FD2 might work, especially as the jet won't be fussy about intake ducting.  I have an idea, will show you on Wednesday.

This BVM Sabre, whoever built it was very gifted!

I find it mildly amusing that I have used 30+ year old technical papers on the real aircraft to help with a semi-scale model.

I used the same source of papers to get an idea of what I was letting myself in for with TSR2 when I built that (not in Dizz's league I know). Although they were not as detailed as for FD2. It does give you a bit of confidence when your results turn out close to the boffins who played with the real thing.

This BVM Sabre, whoever built it was very gifted!

(Attachment Link)

I take it back, nice.  But it wll look even better in different colours! 

Apologies for being a bit off topic but is this Abingdon Jets business open to anyone. I've not got anything suitable to fly and its a bit of a trek from here but sounds like a good day out if the weather is anything like 

Nickk - Look at your PM''s for details of Abingdon.

Sorry, been away for a few days but hopefully you have your answer Nickk.

Fisty has seen the FD2 and we have come to the conclusion that there is nothing to hold on to to give it a decent hand launch, so over the weekend I'll be mod'ing so it can take a bungee.
Pete

Well we didn't get around to flying the FD2 at Abingdon.  If the opportunity arises at Merryfield over the next few months we will go for it, if not looking at 6 April at Abingdon again.  In the meantime over the w/e I made a few bits for the P1154, but I'm having trouble getting my head around designing the fuselage.  Have also put some time in on the Viggen.