Project Alva

[vintage1]

This is something I threw together plan wise last summer, as a simple IPS powered thing, and finally got around to cutting balsa on a few days ago.

Design spec was enough power for a modest wind, but low enough wing loading to land in the garden, and a sort of scale like appearance. Wing was enlarged a bit from first draught and looks a tad silly I think.

Something went wrong in the design and it ended up a very tight fit for everything, so the plans I posted up last summer are not quite as she is now.

Looks on course for sub 7oz with 3s KOKAM 340 and a B geared IPS.

Any ideas on color scheme would be welcome. I thought of making it a 'red cross' air ambulance as a gesture towards the Tsunami situation. I've got blue, silver, dark green, white, ivory, red and yellow solite.

ALVA is A Very Light Vintage Aeroplane. She will be 'registered' as G-ALVA I expect.


Not sure when I will get time to cover and install gear, and fly it, but not too long I hope, though we have gales forecast for the next week.

[Ian Easton]

Looks good Vintage.
I was wondering where you've been lately.

[vintage1]

I was wondering where you've been lately
Don't ask...:)

But the workshop is complete enough to er - work in - anyway.

She went together in record time. It shows if you look closely...

[Blazer]

Top drawer cabin job there Vintage. Looks like a natural for a Mills. (just kidding) What will you cover with? Jim

[vintage1]

Oh, tis done.

Apart from decoration. And final installation of receiver and battery pack - still trying to get the CG BACKwards, which has to be a first for me...

Navy blue fuse and fin, and ivory flying surfaces all in solite with a dayglo orange cowl...in profilm I think. Not sure what it was.


..post pikkies soon.

Motocalc is very positive. About twice the rate of climb of the old IPS model, and that was no slouch. Bit faster but not much, so it won't be much use in over 5mph wind probably.

Spun up the motor and prop - a LOT of thrust - several oz estimated (motocalc says about 3.5)- and a fantastic noise from the prop tips whipping. Motor didn't even get warm - estimated static of 1.8A only, dropping to under an amp in cruise. Should fly twenty minutes - 40 minutes possible if very careful throttle management exercised. Yum Yum.

[zl3vml]

Looks great Vintage1 - congrats. Cant wait to see the rest of the pics.
How about a couple of your shop too?
Mark

[vintage1]

Looks great Vintage1 - congrats. Cant wait to see the rest of the pics.
How about a couple of your shop too?
Mark

Not before I clear it up. Its covered in balsa dust and fragments of balsa.

[vintage1]

pictures...

[zl3vml]

Ahhh....
Now for that calm day to show up.... (wot's that? he grumbles) :)
Certainly looks like it will be a great flier.

I have just worked out what ALVA stands for - a bit slow at times I am afraid.

Mark

Edit - I think a "clean" workshop is just a myth!

[vintage1]

Quick update. Got most electronics installed, and she pulls about 1.7A at 10.8v - about 19W which is spot on.

Motocalc gives me the staggering estmate of 480 feet per minute climb - thats 8 feet a second! - a 22 degree climb angle - top speed of 25mph, and about 20 minutes duration at cruise.

Weight so far without the hatch is about 190g. Spot on.

Could have done with more pitch to increase top speed, but short of fitting an 8x8 APC prop, I can't see much hope...

[Joules]

Hmmm, would this one translate to 2mm depron... I can just see everyones face... Depron vintage models

Joules

[Ian Easton]

I'm depron free and proud :D

[vintage1]

I think it might.

So far is unashamedly balsa wire and a fair bit of 1/64 ply. Oh and carbon fiber and solite. To me, a vintage style model is one that evokes the simple pleasures of tossing a pretty, light weight plane into the air, and having it putter around in a sedate fashion.

If it takes rocket science and titanium to do it, I don't care!

Bad weather is inhibiting the maiden, plus a way of locating the battery securely.

[vintage1]

Mmm. Shes finished and ready. 7oz on the nose.
But CG is at 36% chord...is that too far back?

I pulled the pack as far back as I could, but did I overdo it?

[vintage1]

...and the answer to the previous post questi was 'yes'.

First maiden. Let's try a test glide. I taped a washer on the front for a little more noseweight.

Snapped my only GWS 8x6 prop.

Walked back, cobbled together an APC 8x6E prop,. and tried a power flight.

Maiden #2 Falling leaf' syndrome that I know only too well post Camel. CG WAY too far back. Busted the UC and bent the wires.

I hate maidens.

Walked back again, and in a fit of irritation slammed the pack past the bit of foam stopping it going way forward, and realised CG was now possibly nearly right. Bent U/C straight walked back again and thought 'what the heck'.

Maiden #3 .
It dived straight into the ground. Busted the UC some more and smashed the rear fusealge. You can sort of see what its like from the pictures.

I was about to put my heel on the thing and take up knitting, when I thought 'it can't get much more smashed than this, the tail is still there, OK it wobbles, but if it dived staright in maybe it needs a shade of up trim. If I go and repair it and smash it again I will be truly p***ed so in for a penny...'


...so...

maiden #4 Half up trim, open the throttle, and with a lurch and a wobble, away it went.

For a 5 minute flight. Ok it was behaving oddly in high G manoeuvers due to the tail falling half off. but even so, it had promise.

Not sure, but it seemed a little prone to tip stalling - but hard to say with that fuselage flapping, and I was nowhere near a perfect trim anyway. The wind started to get up progressively, but I still managed to bring it in on its wheels more or less at my feet, before turning over in the rough grass.

So.. some CF rod to stiffen the landing gear, repair the rear fuselage, and try again I guess :D...and get the CG even further forward if possible.

Its going to be OK, this one is. I can feel it. Rate of climb was truly first class. Seems very sensitive in the yaw - possibly due to the short tail moment. Must put in expo or lower rates maybe.

If anyone else builds one CG is somewhere in front of the spar, and certainly never behind it.

Late edit. Fuselage damage is all four longerons cracked - easy repair. Motor stick has broken as well.. This will be back in flying condition by the end of play today, with luck.

[vintage1]

Quick update. More or less repaired, with a bit of lead in the snoot now as well. Got a few minutes test flight in. Some interference possibly due to motor being un run-in, but calm air. Right thrust perfect, downthrust not enough. Very sensitive on all controls - surprisingly so. Loops no problem :D Must add some down elevator mixed in with throttle I think.


Looks like 15-20 minute flights are on, as its probably only taken 75mA/h out of the 350 available.

Cracked its UC plate out landing in the rough again, so a little more work required there.

Overall, though, she comes along. Hope to get a few more flights in in the next few days. Once trimmed out I think this will be a reliable small field calm weather flyer.

[vintage1]

Sneaked out again with her today. Weather has been rubbish,but today, sunny, bright and about 5mph wind.

Incrediblt sensitive to rudder. I have NO idea why. I'll knock back te hrates on that. But after a few minutes of side to side, I finally got my right thumb in tune.. She needs more downthrust,but the motor stick was still a bit wobbly, so that will go in with a new stick.

Delightful ittle sports plane. It only really needs about half throttle for a sensible parkflyer sort of climb. Almost too much power. Seems about twice the power of a 2s LIPO IPS, which is what the maths says. Climbed to a couple of hundred feet no trouble. Was almost losing sight of it when edge on.


A new motor stick and some downthrust will be all that will happen to her today.

I think I have what I wanted. A relaible little small field/garden bit of fun.

YIPPEE ;)

..and the 350 mAh pack only has taken 60mAh after 7-8 minutes of flying.


Looks like 1/2 hour flights are on too.



.

[vintage1]

Just a final note on this. Bit breezy, but got another totally delightful flight out of her again today.

This combination of 3s LIPO and a bog standard IPS is really perfect for small vintage models.

Major climb potential and wind penetration - I landed at a standstill, but was easily able to beat upwind against about 10-13mph winds.

For those that want to try it, the two combinations I have tested in the air are

'A' gearing, 7x6 prop
'B' gearing, 8x6 prop

And on the bench S2 gearing and 6x4 prop. This looks a faster combo and may yet see light of day in a scale twin.

Pack was Kokam 350 3s LIPO.

These combos are totally suitable for any vintage models up to about 9oz I would say. Maybe even more. 'Rubber' conversions and the like.

[zl3vml]

Great stuff that man.
What's the wingspan at?
(still waiting to see some piccies of your workshop:) )
Mark

[vintage1]

I THINK its 31"

The plans are out there somewhere.

Still haven't cleaned the workshop up...

[vintage1]

Came back after a hard day at the beach, almost no wind, and yes, time before dark...for 10 minutes of stall turns, gentle pottering around and so on. Trim is still totally rubbish - needs less side and more downthrust...and some HUGE interference for some reason (Friday night: Taxi/Police transmitter in line of sight?)..but the sheer pleasure of this little plane.. which is totally overpowered really. Its chalk and cheese compared to an IPS plane on 7cells/2s LIPO. I had it so high I couldn't see which way it was going...and landed in the new crops at my feet. Not a mark on it.

And still only had half the pack out of it. So its flying at an average of about 10 watts input...

3 x kokam 350, IPS B gears and an 8x6 has to be THE combo for converting rubber powered planes in the 30-36" span area.

And the servos and reciever are the ones that spent 6 weeks up a tree when my last IPS model ended up there.

[vintage1]

Bad weather has precluded flying, but I got the motor stick .sorted out and ironed the wing free of all visible warps.. yesteaady, and things looked promising, until the prop came loose in flight and sheared off the motor stick glue line.

No damage, but a curtailed flight...however...I drilled the motor stick to take a bit of CF rod for use as alignment, and, propping the model up vertically on its wing TE between a pair of open drawers reglued the stick in...using the bit of CF rod to check alignment. Then I ground the rod off once the glue set. There is a very very slight bit of right thrust now.

What a revelation! without a wing warp and left rudder fighting the the right thrust, it was as stable and predictable as a trainer should be, and the odd tendency to drop a wing GONE. Even in 15mph winds it was so much more controllable...

I managed to hover it into the wind at about 100ft altitude...and it had plenty of speed to make it upwind with throttle and down applied...and the whole plane showed no nasty tendencies at all any more.

Strange how a warp and a twisted thrust line can make a plane twitchy and hard to control.

[HELModels]

What a revelation! without a wing warp and left rudder fighting the the right thrust, it was as stable and predictable as a trainer should be, and the odd tendency to drop a wing GONE. Even in 15mph winds it was so much more controllable...

I managed to hover it into the wind at about 100ft altitude...and it had plenty of speed to make it upwind with throttle and down applied...and the whole plane showed no nasty tendencies at all any more.

Strange how a warp and a twisted thrust line can make a plane twitchy and hard to control.

Now, imagine trying to learn to fly and having to deal with trim issues at the same time. Was that the design, conditions or bad pilot input. My little CDROM powered buzzard(havent really named it yet) allowed me to learn to fly, but to fly really well I had to get the trim exactly right. Every time I tried to turn left, it would want to level the wings and I would get into these oscillations that sometimes ended with stall/spin. Power off was much more predictable and fortunately allowed good landings.

Congratulations on surviving the debugging process!

[vintage1]

well, the old Alva was a bit wonky at the end of last year, and I stole its powerplant for something else, but anyway a new IPS A geared unit off ebay plus the fact a model fell off its celing hook and ripped its covering prompted me into a repair session, and the Alva got its cracked main spar sorted and wings re done and a new power plant added. Since it got treed last year and slightly nerfed its pack, I popped an etech 450 3s in it and a GWS 7x6 prop on the 'A' motor..

..with a little more weight from the pack, it was fast, stable and I even managed a slow roll..sort of.

Motocalc reckons 30mph top speed and it looked like it..looked also about 30 degree climb.

I'd forgotten how much fun it was...almost back to "most repairable models now repaired"..again.

[Snorks]

I thought I was having a dizzy spell.....thinking "this looks like the SAME colour scheme as the last thing Vintage built.." Then I saw the date. I'm in the same boat vintage. I have a few hanging from the roof to repair that I know I will fall in love with all over again- if i could just get motivated to fix 'em. The model falling off its hook in the roof is yet more proof of my theory that somewhere between 90 to 100% of all damage to models either happens in the workshop (hangar rash) transorting the thing to the flying field or just sitting there on the ground waiting to be flown.... worst one was when I was helping a new guy at the club with a flying lesson, standing by him ready to take over (no buddy cord) when all of a sudden a huge gust of wind flipped two of my models over breaking the wings!

[vintage1]

I thought I was having a dizzy spell.....thinking "this looks like the SAME colour scheme as the last thing Vintage built.." Then I saw the date. I'm in the same boat vintage. I have a few hanging from the roof to repair that I know I will fall in love with all over again- if i could just get motivated to fix 'em. The model falling off its hook in the roof is yet more proof of my theory that somewhere between 90 to 100% of all damage to models either happens in the workshop (hangar rash) transorting the thing to the flying field or just sitting there on the ground waiting to be flown.... worst one was when I was helping a new guy at the club with a flying lesson, standing by him ready to take over (no buddy cord) when all of a sudden a huge gust of wind flipped two of my models over breaking the wings!

Well the alva has been

1/. squeezed too hard in the wrong place. Busted longeron

2/. broke its back on maiden due to rear CG and massively too much control throw.

3/. Broke its wing when a friend flew it into the Tree That Eats Planes.

4/ Broke its wing again after I fixed it when the dog wagged its tail as I was carrying it past him.

But it was last years 'reliable evening flyer, and I HAD repaired it last year, but when I launched it, I noticed it had twice the dihedral on the broken wing side...but only in the air. I mised the cracked main spar didn't I? :D :D

Only just got around to fixing it that's all.

[vintage1]

Seems I never posted the plans up for this.

Well here they are in PDF format. Not quite as she ended up finally, but good enough to replicate her.

[johnvb]

She's a cutie. Thanks for the plan. :)

[vintage1]

Ah well..after a suggestion..I redrew this one for laser cutting..it may appear as a kit.

The fuselage covering on the proto is frankly shameful, for reasons I won't go into, and the wheels were just what was lying around and far too big, but essentially it flew this afternoon.

AUW bang on 8oz, and it solved a lot of the originals problems..

- its longer in the nose and tail and has a bit more wing area. This got me a CG spot on with no lead.

- its wider so as to make installation a LOT easier..two servos with big arms side by side, and bags of room for radio gear as you can see.

- its tabbed to heck to make it fall together and has the right side and downthrust from the word go. That bit I did get right for a change.

The maiden was 'lively' to say the least..somehow I had the trims badly wrong and WAY too much rudder throw..but after I found a stick position that approximated level flight and had some height I whacked the trims over and got it tamed. Bags of power for an IPS.

I chucked it up three times to make sure, and hough conditions weren't ideal the snappy rudder response and adequacy of power got me out of plenty of tight corners though I had a nasty moment heading for the trees when I dialled out nearly all the rudder on the computer, and just managed to turn it in time before remembering to go full rate :D

Anyway, if anyone is interested in a cut one, let me know.

It can in fact cope with more breeze and turbulence than it appears. I reckon it was 5 mph +- 5mph out there today, and it cracks along at about 20mph airspeed..so although its up and down and dancing around, it can cope with a 5 mph lull without falling out of the sky, and the excessive rudder response and dihedral means you can set it straight very quickly.

I'll probably scrap this one and build a second beta model fairly quickly..

Quick specs are..
Span 31" or so.
IPS "A" unit.
7x6 prop and cut down GWS spinner.
3s etech 450 pack (enough for at least half an hour)
AUW 8oz dead.
Ripmax Xtra 12A ESC in this one
2x9g servos (could use 5g, but the rails were cut for 9g's)
custom RX from nice e-zoner.

Motocalc estimates 350 feet per minute climb, but I reckon its better than that on a fresh pack, and a top speed of 25mph, which seems about right more or less, and a stall speed of around 12 mph, which is also fairly close.

If you leave the motor ticking over, and point the nose down, the prop drag means it comes down fast without actually building up too much airspeed..which makes it pretty easy to land in tight places in calm conditions.

So a nice bit of fun for the summer.