Post by skyboyken on Apr 21, 2008 20:57:55 GMT 10
Hi guys,
because of the very ordinary weather at my place on Sunday (Bribie) I finished my 48" Moth rather than go flying. I've since found out it was quite nice at Bald Knob! Oh well, at least I got a plane finished.
I don't have any pics as yet, but I built the Moth using "Burrly" covering from Karl 'The Predator' in the US. That made things really quick and easy because to do the wing I used no Spackle, no fibre tape and no Goop at all!! I just built the Moth, covered the wing with Burrly and the elevons and tail with Plasti-Ply Light, did the fuse in fibre tape, 3M77 (I was in a hurry) and Profilm, and joined the 2 with Goop.
I'm really happy with the Burrly. I made a couple of mistakes as it was my first time with it (was it good for you too??? - stop that!!) but I'm totally satisfied with the results. Not least the weight which came out at 18 1/2 oz, about 2 oz lighter than Mark's Moth which is using Goop/tape/Profilm.
It's noticeably stiffer as well and that's why I used Burrly in the first place - because I'd seen Ezza's dad's Reaper and been impressed with the surface finish (with no prep) and the stiffness with Burrly. I do however have an extra spar of vertical carbon ribbon to add even more to the stiffness so although I'm confident the Burrly helps I can't truly say how much.
The other thing I did that I'm really happy with is to use a 5 cell Rx pack I made from 800MAh Eneloop cells - 4 from Tandy and 1 from Vanders - thanks Mark! Boy does that make the servos (HS-65HB - my standard small servo) fast! In fact I'm very pleased that there is NO slop in the control system - that's a necessity in the Moth because the total elevator throw when it's tuned will be about 1mm up and 1mm down! At the moment I have it at about 1.5mm but there's more to that story below.
Do you get that I'm pretty happy with this plane? I am, but only after it scared the heck out of me!
In the build instructions NCFM (makers of the Moth) bang on about how criticl it is to set the CG accurately because the range is so small, and how you mustn't just balance it on your fingers because that's just not good enough for their precious plank - blah blah blah...
Heard it all before!!!
Well do you know what?? They're absolutely right! As I found out too late...
They said pretty much the same thing for the Reaper and I CG'ed that up on my fingers, so I did the same for the Moth. Big mistake. I duly finished the plane, put it carefully in the back of the car with the Reaper so they could get to know one another and set off for Bald Knob this morning. I love Bald Knob for maidens - the whole place is covered in looooooong grass!
I checked Seabreeeze before leaving and it said about 15 knots (30Km/hr) SSE - perfect for a maiden and for DS at the Camel Hump after! Well, it was SSE alright, just more like 5-7 knots than 15. I reckon Seabreeze is set up to exaggerate the windspeed to encourage people to get out and kitesurf etc! It never blows as hard as that site says it will, and certainly not today.
So I arrive after having called Vanders and Sean and to my surprise having both of them say they'd come for a fly, get out the Moth and start test glides in the long grass on top of the knob. Now I've done this several times before with planes and the drill is that you chuck them a little up and not too hard so you get to check the elevon trim is OK before heaving them off over the never never. So I toss the Moth and it goes up, then pitches hard down and thwap into the grass!! OK says I that needs up trim! So I put some in and it's better but not really controllable - which I put down to flying too slowly for what is supposed to be a fast plank after all.
So I get it trimmed close enough and even though it's behaving a little strangely I figure I'll toss it over the edge and sort it out from there - after all I've done this before right!
(Do you sort of get the feeling at this point that this thread belongs in the Klutz thread? You'd be right you know!)
The South side of the knob has a nice light breeze blowing straight at it, certainly more than Vanders had when he maidened his and that went great, so I toss the Moth out - and away it goes, neat as you please, cruising out over the never never. A very satisfying sight.
Until I put in a control movement and all hell breaks loose!!!
All I did was put in a small amount of up elevator to correct the flight path, and this with 40% expo - it really was a small amount. Ooops - did I mention I had high rates selected and that was 3mm up and down - about twice the recommended throw - just to be safe!
I have never in my life seen or experienced anything remotely like what happened next. There's my nice new plane - still fairly close to the hill and going fairly slowly - and when I put in up elevator it performs a fairly tight but very nice half loop - in the downwards direction! Oh dear!!! What the &^^% am I supposed to do now?
Fortunately the plane has a mind of its own and as I'm still holding up - full up by now - it then performs another half loop - upwards this time - to level and beyond. This is just as well as it's just about out of height and is now going much faster! So I get off the elevator at just above level, roll towards the hill and gently pull up again. This time it does go up for a moment, which now means it turns toward the hill (mostly) and then it goes inverted again as it disappear down the hill at a rate of knots. Bugger!! So I let go the elevator and thank heavens it crashes into the aforementioned long grass and I go for a mostly vertical walk to get it back.
Well that got my attention well and truly!
To cut a long story short I spent the next hour adding and subtracting ballast while playing with control throws and going for more than a few vertical walks to get the blasted thing back!
Finally I toss it out - expecting to have to fight it every inch of the way because that's what I've been doing for the last hour - and it flies beautifully. Stable in pitch - HOORAY! - yet fairly responsive. The problem now is that it pitches up with left roll and down with right roll. So a few more short flights to get the aileron throws dialed, and relax that it finally isn't unstable in pitch, and my mobile goes off which breaks my concentration and I drop it into the hillside again so I can have yet another vertical walk. Oh joy.
It was none other than Sean arriving, and with a great big box in his car too! He tells me he hasn't brought any planes because he couldn't see me or my car, but he does have his brand new Erwin 2m mouldie just picked up from the PO. Open it open it says I
.
Gorgeous is the word. Just gorgeous. I'll leave any more than that to Sean.
Back to flying and Mark has now arrived and we've both cleaned up our excess saliva from the Erwin we've been drooling over and are flying our Moths together at the SE corner of the knob quite happily. Now this should have told me the wind had swung away from the Camel Hump but no, never one to lat a plan go easily I say 'Let's go DS the Hump!'.
So Mark and I stroll down the hill and cause the grazing cows to vacate the top of the knob, causing us to do the dance of poo avoidance. Sean says he'll follow later, but the cunning bugger never does.
I toss out the Moth, after all this is what I built it for - light to medium wind frontside fun and light wind DS - and it's struggling to stay at launch height, let alone climb a little so I can have a good positive dive in for DS. Anyway it's above the hill So I drop it in and manage about 3 wobbly circles, gaining and losing energy as I go but losing over all. Even though the Moth showed me it has good penetration it doesn't carry its energy like the Reaper. At about half the weight and 80% the wing area that's no real surprise I guess. Still it was good enough that I'm confident it'll be be fine when I get the chance to tune it better.
Next I toss the Reaper out (these are the conditions it's tuned for) and it performs like the thoroughbred it is. It climbs in the light patchy lift and carries its energy through the lulls. I drop it in and get 6-8 DS circles which are really slow but the plane carries its energy so well I could have kept it going for a while, but I elect to punch through to the frontside where there's suddenly no wind at all and the next thing I know I'm landing.
Well I'm trying to land at least.
What I'm actually doing is flying straight at the hill well below me and pulling up at the last moment to discover the blasted plane is carrying its energy so well it climbs all the way up the hill, over the top and straight at my face going way too fast for comfort! So I figured I either catch it or wear it so I better catch it! And I do! That's a first and I very much hope a last as well.
Well as the lift has totally died at the Hump Mark and I hump ourselves and our planes back up to the top to join Sean who's happily flying his Carbon Bird at the SE corner. We joined him and flew for a while but the lift had really died so what we mostly did is shoot the breeze - as you do.
So at the end of a very exciting (for often the wrong reasons) day I'm pretty happy with the Moth. It has shown me that it takes careful tuning to get it to fly and more tuning yet to get it to fly at its best. I'm confident though that it's a keeper and I expect to have it going really well after a few more (more relaxed) flying sessions.
Go Great!
because of the very ordinary weather at my place on Sunday (Bribie) I finished my 48" Moth rather than go flying. I've since found out it was quite nice at Bald Knob! Oh well, at least I got a plane finished.
I don't have any pics as yet, but I built the Moth using "Burrly" covering from Karl 'The Predator' in the US. That made things really quick and easy because to do the wing I used no Spackle, no fibre tape and no Goop at all!! I just built the Moth, covered the wing with Burrly and the elevons and tail with Plasti-Ply Light, did the fuse in fibre tape, 3M77 (I was in a hurry) and Profilm, and joined the 2 with Goop.
I'm really happy with the Burrly. I made a couple of mistakes as it was my first time with it (was it good for you too??? - stop that!!) but I'm totally satisfied with the results. Not least the weight which came out at 18 1/2 oz, about 2 oz lighter than Mark's Moth which is using Goop/tape/Profilm.
It's noticeably stiffer as well and that's why I used Burrly in the first place - because I'd seen Ezza's dad's Reaper and been impressed with the surface finish (with no prep) and the stiffness with Burrly. I do however have an extra spar of vertical carbon ribbon to add even more to the stiffness so although I'm confident the Burrly helps I can't truly say how much.
The other thing I did that I'm really happy with is to use a 5 cell Rx pack I made from 800MAh Eneloop cells - 4 from Tandy and 1 from Vanders - thanks Mark! Boy does that make the servos (HS-65HB - my standard small servo) fast! In fact I'm very pleased that there is NO slop in the control system - that's a necessity in the Moth because the total elevator throw when it's tuned will be about 1mm up and 1mm down! At the moment I have it at about 1.5mm but there's more to that story below.
Do you get that I'm pretty happy with this plane? I am, but only after it scared the heck out of me!
In the build instructions NCFM (makers of the Moth) bang on about how criticl it is to set the CG accurately because the range is so small, and how you mustn't just balance it on your fingers because that's just not good enough for their precious plank - blah blah blah...
Heard it all before!!!
Well do you know what?? They're absolutely right! As I found out too late...
They said pretty much the same thing for the Reaper and I CG'ed that up on my fingers, so I did the same for the Moth. Big mistake. I duly finished the plane, put it carefully in the back of the car with the Reaper so they could get to know one another and set off for Bald Knob this morning. I love Bald Knob for maidens - the whole place is covered in looooooong grass!
I checked Seabreeeze before leaving and it said about 15 knots (30Km/hr) SSE - perfect for a maiden and for DS at the Camel Hump after! Well, it was SSE alright, just more like 5-7 knots than 15. I reckon Seabreeze is set up to exaggerate the windspeed to encourage people to get out and kitesurf etc! It never blows as hard as that site says it will, and certainly not today.
So I arrive after having called Vanders and Sean and to my surprise having both of them say they'd come for a fly, get out the Moth and start test glides in the long grass on top of the knob. Now I've done this several times before with planes and the drill is that you chuck them a little up and not too hard so you get to check the elevon trim is OK before heaving them off over the never never. So I toss the Moth and it goes up, then pitches hard down and thwap into the grass!! OK says I that needs up trim! So I put some in and it's better but not really controllable - which I put down to flying too slowly for what is supposed to be a fast plank after all.
So I get it trimmed close enough and even though it's behaving a little strangely I figure I'll toss it over the edge and sort it out from there - after all I've done this before right!
(Do you sort of get the feeling at this point that this thread belongs in the Klutz thread? You'd be right you know!)
The South side of the knob has a nice light breeze blowing straight at it, certainly more than Vanders had when he maidened his and that went great, so I toss the Moth out - and away it goes, neat as you please, cruising out over the never never. A very satisfying sight.
Until I put in a control movement and all hell breaks loose!!!
All I did was put in a small amount of up elevator to correct the flight path, and this with 40% expo - it really was a small amount. Ooops - did I mention I had high rates selected and that was 3mm up and down - about twice the recommended throw - just to be safe!
I have never in my life seen or experienced anything remotely like what happened next. There's my nice new plane - still fairly close to the hill and going fairly slowly - and when I put in up elevator it performs a fairly tight but very nice half loop - in the downwards direction! Oh dear!!! What the &^^% am I supposed to do now?
Fortunately the plane has a mind of its own and as I'm still holding up - full up by now - it then performs another half loop - upwards this time - to level and beyond. This is just as well as it's just about out of height and is now going much faster! So I get off the elevator at just above level, roll towards the hill and gently pull up again. This time it does go up for a moment, which now means it turns toward the hill (mostly) and then it goes inverted again as it disappear down the hill at a rate of knots. Bugger!! So I let go the elevator and thank heavens it crashes into the aforementioned long grass and I go for a mostly vertical walk to get it back.
Well that got my attention well and truly!
To cut a long story short I spent the next hour adding and subtracting ballast while playing with control throws and going for more than a few vertical walks to get the blasted thing back!
Finally I toss it out - expecting to have to fight it every inch of the way because that's what I've been doing for the last hour - and it flies beautifully. Stable in pitch - HOORAY! - yet fairly responsive. The problem now is that it pitches up with left roll and down with right roll. So a few more short flights to get the aileron throws dialed, and relax that it finally isn't unstable in pitch, and my mobile goes off which breaks my concentration and I drop it into the hillside again so I can have yet another vertical walk. Oh joy.
It was none other than Sean arriving, and with a great big box in his car too! He tells me he hasn't brought any planes because he couldn't see me or my car, but he does have his brand new Erwin 2m mouldie just picked up from the PO. Open it open it says I
.Gorgeous is the word. Just gorgeous. I'll leave any more than that to Sean.
Back to flying and Mark has now arrived and we've both cleaned up our excess saliva from the Erwin we've been drooling over and are flying our Moths together at the SE corner of the knob quite happily. Now this should have told me the wind had swung away from the Camel Hump but no, never one to lat a plan go easily I say 'Let's go DS the Hump!'.
So Mark and I stroll down the hill and cause the grazing cows to vacate the top of the knob, causing us to do the dance of poo avoidance. Sean says he'll follow later, but the cunning bugger never does.
I toss out the Moth, after all this is what I built it for - light to medium wind frontside fun and light wind DS - and it's struggling to stay at launch height, let alone climb a little so I can have a good positive dive in for DS. Anyway it's above the hill So I drop it in and manage about 3 wobbly circles, gaining and losing energy as I go but losing over all. Even though the Moth showed me it has good penetration it doesn't carry its energy like the Reaper. At about half the weight and 80% the wing area that's no real surprise I guess. Still it was good enough that I'm confident it'll be be fine when I get the chance to tune it better.
Next I toss the Reaper out (these are the conditions it's tuned for) and it performs like the thoroughbred it is. It climbs in the light patchy lift and carries its energy through the lulls. I drop it in and get 6-8 DS circles which are really slow but the plane carries its energy so well I could have kept it going for a while, but I elect to punch through to the frontside where there's suddenly no wind at all and the next thing I know I'm landing.
Well I'm trying to land at least.
What I'm actually doing is flying straight at the hill well below me and pulling up at the last moment to discover the blasted plane is carrying its energy so well it climbs all the way up the hill, over the top and straight at my face going way too fast for comfort! So I figured I either catch it or wear it so I better catch it! And I do! That's a first and I very much hope a last as well.
Well as the lift has totally died at the Hump Mark and I hump ourselves and our planes back up to the top to join Sean who's happily flying his Carbon Bird at the SE corner. We joined him and flew for a while but the lift had really died so what we mostly did is shoot the breeze - as you do.
So at the end of a very exciting (for often the wrong reasons) day I'm pretty happy with the Moth. It has shown me that it takes careful tuning to get it to fly and more tuning yet to get it to fly at its best. I'm confident though that it's a keeper and I expect to have it going really well after a few more (more relaxed) flying sessions.
Go Great!
