Depron Foam scratch-build Eurofighter
Discussion
My T-Rex 450 heli died again yesterday, £200 of damage after literally seconds of flight following a £185 rebuild. Looks like a control arm in the head failed.
Enough's enough so I threw myself into my Eurofighter foamie that I've been messing about with since my Cessna jammed a servo and met a tree at speed.
Here's some pics.
Truth be told I'm worried about it. It's heavy and there's not a lot of lift when you throw it around at low speed, unlike my Cessna which would lift nicely if you threw it across the room. I kind of suspect it's just too heavy. Will find out when the weather clears and I can actually take her for a maiden flight.
Can't find the site where I downloaded the plans now but there are loads out there if anyone else is interested.
Does anyone else here scratchbuild?
Enough's enough so I threw myself into my Eurofighter foamie that I've been messing about with since my Cessna jammed a servo and met a tree at speed.
Here's some pics.
Truth be told I'm worried about it. It's heavy and there's not a lot of lift when you throw it around at low speed, unlike my Cessna which would lift nicely if you threw it across the room. I kind of suspect it's just too heavy. Will find out when the weather clears and I can actually take her for a maiden flight.
Can't find the site where I downloaded the plans now but there are loads out there if anyone else is interested.
Does anyone else here scratchbuild?
Edited by _Al_ on Sunday 26th July 17:26
I have done and in the past similar models and 'build in lightness' was always my motto, although I didn't succeed every time!
I once scratch built an F8 Crusader which looked absolutely fantastic pre first flight. C of G was fine, 40 sized engine hidden well etc. Unfortunately it was way over weight and although it got off the ground, it all ended pretty quickly and soon became a box of bits again!
I haven't had any inclination to build or fly for some years and currently have a few models and two helicopters in the garage no doubt going rusty and US. Since starting my business 13 years ago, I just haven't had time to 'play' with them
Your Eurofighter looks good and I suspect providing you ave enough grunt will fly just fine. Flat winged aircraft can fly very well indeed and fly quite fast as well as slowly. You may find in a decent wind you can get the craft to literally fly backwards by using a combination of throttle and a steep wing angle into the wind.
Would be good to see a video of its maiden flight!
I once scratch built an F8 Crusader which looked absolutely fantastic pre first flight. C of G was fine, 40 sized engine hidden well etc. Unfortunately it was way over weight and although it got off the ground, it all ended pretty quickly and soon became a box of bits again!
I haven't had any inclination to build or fly for some years and currently have a few models and two helicopters in the garage no doubt going rusty and US. Since starting my business 13 years ago, I just haven't had time to 'play' with them
Your Eurofighter looks good and I suspect providing you ave enough grunt will fly just fine. Flat winged aircraft can fly very well indeed and fly quite fast as well as slowly. You may find in a decent wind you can get the craft to literally fly backwards by using a combination of throttle and a steep wing angle into the wind.
Would be good to see a video of its maiden flight!
The F8 Crusader looks very nice. I hadn't heard of it before.
I definitely intend to get a video. I have a flycamone, it needs a new battery but I'll try and sort it then nosemount it for the maiden (C of G is borderline too far back anway). Don't have a great camera but it should be good enough to show what's happening from the ground.
May be a while yet because I intend to build a spare 'snotter' to get my eye back in. My last flight with the Cessna was over 6 months ago so I badly need the practice. Going to get some sim time this evening as preparation but I only have the cheap sim so it's not that valuable.
Not to imply anything about the life expectancy of my Typhoon but my next proper foam plane will probably be an F22 then maybe an SR71. I really enjoy the fact you can just build more planes...
I definitely intend to get a video. I have a flycamone, it needs a new battery but I'll try and sort it then nosemount it for the maiden (C of G is borderline too far back anway). Don't have a great camera but it should be good enough to show what's happening from the ground.
May be a while yet because I intend to build a spare 'snotter' to get my eye back in. My last flight with the Cessna was over 6 months ago so I badly need the practice. Going to get some sim time this evening as preparation but I only have the cheap sim so it's not that valuable.
Not to imply anything about the life expectancy of my Typhoon but my next proper foam plane will probably be an F22 then maybe an SR71. I really enjoy the fact you can just build more planes...
Edited by _Al_ on Sunday 26th July 20:12
_Al_ said:
My T-Rex 450 heli died again yesterday, £200 of damage after literally seconds of flight following a £185 rebuild. Looks like a control arm in the head failed.
Enough's enough so I threw myself into my Eurofighter foamie that I've been messing about with since my Cessna jammed a servo and met a tree at speed.
Here's some pics.
Truth be told I'm worried about it. It's heavy and there's not a lot of lift when you throw it around at low speed, unlike my Cessna which would lift nicely if you threw it across the room. I kind of suspect it's just too heavy. Will find out when the weather clears and I can actually take her for a maiden flight.
Can't find the site where I downloaded the plans now but there are loads out there if anyone else is interested.
Does anyone else here scratchbuild?
Looks like a flat plate wing (more or less), so you won't get much lift by just chucking it about - you need a bit of speed and some angle of attack. If your Cessna had a moulded wing with a section then this is a more efficient lifting section and would explain the difference.Enough's enough so I threw myself into my Eurofighter foamie that I've been messing about with since my Cessna jammed a servo and met a tree at speed.
Here's some pics.
Truth be told I'm worried about it. It's heavy and there's not a lot of lift when you throw it around at low speed, unlike my Cessna which would lift nicely if you threw it across the room. I kind of suspect it's just too heavy. Will find out when the weather clears and I can actually take her for a maiden flight.
Can't find the site where I downloaded the plans now but there are loads out there if anyone else is interested.
Does anyone else here scratchbuild?
Edited by _Al_ on Sunday 26th July 17:26
I built an own design depron profile model (similar kind of thing) and it glides like a brick, but flies under power unbelievably well. Just try it!
Is it your own design?
I got the plans off RCGroups, modified it by adding an aerofoil for a bit more lift as I'm a relative novice with planes and I want it to be stable.
I wish I'd bought the depron from robot birds - my other supplier was not *quite* as good in the value for money stakes.
I keep reminding myself that I committed to practicing on a snotter - looking out of the window now it's hard not to head down the local park..
The cessna is a profiled wing and I did expect it to lift better, just maybe not so much better.
Do you guys have any recommendations for control rods? Mine are ok but a bit floppy.
I'd like to do my own plans some time soon. I'm not sure what to aim at though. F14 has always been a favorite but it is quite fiddly to do it justice.
I wish I'd bought the depron from robot birds - my other supplier was not *quite* as good in the value for money stakes.
I keep reminding myself that I committed to practicing on a snotter - looking out of the window now it's hard not to head down the local park..
The cessna is a profiled wing and I did expect it to lift better, just maybe not so much better.
Do you guys have any recommendations for control rods? Mine are ok but a bit floppy.
I'd like to do my own plans some time soon. I'm not sure what to aim at though. F14 has always been a favorite but it is quite fiddly to do it justice.
Edited by _Al_ on Monday 27th July 18:39
_Al_ said:
Do you guys have any recommendations for control rods? Mine are ok but a bit floppy.
If they're floppy because of the length, cyano a piece of short tube mid way along them as a guide. Edited by _Al_ on Monday 27th July 18:39
If you mean the ends themselves are floppy in the holes, rub them over with a candle (or car wax), install them into the horns and put a drop of cyano where they fit into the hole. When it's fully set (use accelerator if you've got it) you should be able to crack them and they'll be a perfect fit. (this may be turn out to be a disaster, but I have done it succesfully in the past, someone in our flying club told me about it).
Cheers,
Thanks for the tip.
I did the maiden tonight. Forgot to video it in all the excitement. You didn't miss much. It has plenty of power, my girlfriend ran and threw it into the wind and it accellerated very hard - into the ground.
The nose was way to heavy and there was no way it could lift. Going to try the battery further back when I've glued the bits back together.
Think I need a much much smaller battery...
The important part is that it did what I wanted it to do - every part except the foam survived just fine, unlike the helicopter.
I did the maiden tonight. Forgot to video it in all the excitement. You didn't miss much. It has plenty of power, my girlfriend ran and threw it into the wind and it accellerated very hard - into the ground.
The nose was way to heavy and there was no way it could lift. Going to try the battery further back when I've glued the bits back together.
Think I need a much much smaller battery...
The important part is that it did what I wanted it to do - every part except the foam survived just fine, unlike the helicopter.
Edited by _Al_ on Monday 27th July 22:46
Just noticed on the last few pics - I see you're using a Kline-Fogleman Airfoil not a flat plate. Was this on the original plan? If so, did it show any radiussing of the leading edges? You don't appear to have any.
Also, I've never tried a KF section, but I understand that the top plate should cover about 40% of chord from the leading edge - you seem to have a bit less than this. Is the thickness of the 'thick' part of the wing approximately an 8% section (rather than just double thickness)?
Not saying anything wrong with it by any means - it looks a fine model, but you might want to delve a bit further into KF airfoil theory.
Cheers,
Also, I've never tried a KF section, but I understand that the top plate should cover about 40% of chord from the leading edge - you seem to have a bit less than this. Is the thickness of the 'thick' part of the wing approximately an 8% section (rather than just double thickness)?
Not saying anything wrong with it by any means - it looks a fine model, but you might want to delve a bit further into KF airfoil theory.
Cheers,
_Al_ said:
Thanks for the tip.
I did the maiden tonight. Forgot to video it in all the excitement. You didn't miss much. It has plenty of power, my girlfriend ran and threw it into the wind and it accellerated very hard - into the ground.
The nose was way to heavy and there was no way it could lift. Going to try the battery further back when I've glued the bits back together.
Think I need a much much smaller battery...
Where is the balance point currently?I did the maiden tonight. Forgot to video it in all the excitement. You didn't miss much. It has plenty of power, my girlfriend ran and threw it into the wind and it accellerated very hard - into the ground.
The nose was way to heavy and there was no way it could lift. Going to try the battery further back when I've glued the bits back together.
Think I need a much much smaller battery...
What battery are you running? looks like a 3 cell LiPo? 'bout 1000mAh?
Take a video next time!
Cheers,
dr_gn said:
Just noticed on the last few pics - I see you're using a Kline-Fogleman Airfoil not a flat plate. Was this on the original plan? If so, did it show any radiussing of the leading edges? You don't appear to have any.
Also, I've never tried a KF section, but I understand that the top plate should cover about 40% of chord from the leading edge - you seem to have a bit less than this. Is the thickness of the 'thick' part of the wing approximately an 8% section (rather than just double thickness)?
Not saying anything wrong with it by any means - it looks a fine model, but you might want to delve a bit further into KF airfoil theory.
Cheers,
It wasn't part of the original plan - I just bodged it out of the leftover foam having seen a vid on youtube. Will definitely read up on it. I did the radius after taking the pictures but it was guestimated.Also, I've never tried a KF section, but I understand that the top plate should cover about 40% of chord from the leading edge - you seem to have a bit less than this. Is the thickness of the 'thick' part of the wing approximately an 8% section (rather than just double thickness)?
Not saying anything wrong with it by any means - it looks a fine model, but you might want to delve a bit further into KF airfoil theory.
Cheers,
I'm new to planes having spent most of my spare time studying helicopters.
Thanks for the info - there's more to this than meets the eye!
It's a 1300 pack, which is probably overkill. The balance was about half way along the fuselage. I did have the camera with me - just got excited and forgot.
Edited by _Al_ on Monday 27th July 22:54
_Al_ said:
dr_gn said:
Just noticed on the last few pics - I see you're using a Kline-Fogleman Airfoil not a flat plate. Was this on the original plan? If so, did it show any radiussing of the leading edges? You don't appear to have any.
Also, I've never tried a KF section, but I understand that the top plate should cover about 40% of chord from the leading edge - you seem to have a bit less than this. Is the thickness of the 'thick' part of the wing approximately an 8% section (rather than just double thickness)?
Not saying anything wrong with it by any means - it looks a fine model, but you might want to delve a bit further into KF airfoil theory.
Cheers,
It wasn't part of the original plan - I just bodged it out of the leftover foam having seen a vid on youtube. Will definitely read up on it. I did the radius after taking the pictures but it was guestimated.Also, I've never tried a KF section, but I understand that the top plate should cover about 40% of chord from the leading edge - you seem to have a bit less than this. Is the thickness of the 'thick' part of the wing approximately an 8% section (rather than just double thickness)?
Not saying anything wrong with it by any means - it looks a fine model, but you might want to delve a bit further into KF airfoil theory.
Cheers,
I'm new to planes having spent most of my spare time studying helicopters.
Thanks for the info - there's more to this than meets the eye!
It's a 1300 pack, which is probably overkill. The balance was about half way along the fuselage. I did have the camera with me - just got excited and forgot.
Edited by _Al_ on Monday 27th July 22:54
Assuming this is correct, it may just be something as daft as you having some down trim in there initially.
Don't take this the wrong way, but : which way have you got the elevons moving for 'up' ?
Cheers,
Edited by dr_gn on Monday 27th July 23:06
Good point - I'd forgotten about that. I've just laid the plan over the (re-glued) model and the C of G actually seems very good even with the battery on there. It's pretty much spot on.
Pics:
Damage
Repaired (showing controls set to bring the nose up).
Repaired (showing controls set to bring the nose down).
I do note that the controls don't move equally about the centre position. I get a lot more elevon going down than I do going up. I've tried to adjust the DX6i but I'm not getting the results I expect. It seems when I use travel adjust it alters the mix left/right rather than the limits up/down.
Any ideas?
Pics:
Damage
Repaired (showing controls set to bring the nose up).
Repaired (showing controls set to bring the nose down).
I do note that the controls don't move equally about the centre position. I get a lot more elevon going down than I do going up. I've tried to adjust the DX6i but I'm not getting the results I expect. It seems when I use travel adjust it alters the mix left/right rather than the limits up/down.
Any ideas?
Edited by _Al_ on Monday 27th July 23:17
Wouldn't worry too much about the travel - I've never used a Spektrum Tx, so don't know how to programme it. Controls look good apart from that.
What I'd do next is glide test it into some long grass to find the balance point (add and remove some bits of lead or something), then try it with power. Beware moving the balance point too far back: it will result in a very twitchy model.
You might have to adjust balance or thrust angles once it's flown under power, but I can't see any reason why it shouldn't fly once that's sorted out.
Might be worth launching it underarm too, in an upward arc - I've had a bad launch which removed the front end of my Extra 300S (which was perfectly set up!).
Good Luck.
What I'd do next is glide test it into some long grass to find the balance point (add and remove some bits of lead or something), then try it with power. Beware moving the balance point too far back: it will result in a very twitchy model.
You might have to adjust balance or thrust angles once it's flown under power, but I can't see any reason why it shouldn't fly once that's sorted out.
Might be worth launching it underarm too, in an upward arc - I've had a bad launch which removed the front end of my Extra 300S (which was perfectly set up!).
Good Luck.
Thanks for all the advice. I appreciate your patience here! I was just watching the Firefox vid on the RC powers thread. The guy there from West Sussex got within inches of having the same issue I did after launch but he just got enough airspeed. Can't help but think that if my girlfriend was a little taller this may have been a very different story..
I'm in London so there's not much long grass round here. All the glide tests I've tried imply that it's nose heavy but judging by the CofG lines on the plan it should be ok.
Are my bodged aerofoils doing more harm than good?
I'm in London so there's not much long grass round here. All the glide tests I've tried imply that it's nose heavy but judging by the CofG lines on the plan it should be ok.
Are my bodged aerofoils doing more harm than good?
Edited by _Al_ on Monday 27th July 23:45
_Al_ said:
Thanks for all the advice. I appreciate your patience here! I was just watching the Firefox vid on the RC powers thread. The guy there from West Sussex got within inches of having the same issue I did after launch but he just got enough airspeed. Can't help but think that if my girlfriend was a little taller this may have been a very different story..
I'm in London so there's not much long grass round here. All the glide tests I've tried imply that it's nose heavy but judging by the CofG lines on the plan it should be ok.
Are my bodged aerofoils doing more harm than good?
Have you tried slight up elevator on a glide test then?I'm in London so there's not much long grass round here. All the glide tests I've tried imply that it's nose heavy but judging by the CofG lines on the plan it should be ok.
Are my bodged aerofoils doing more harm than good?
Edited by _Al_ on Monday 27th July 23:45
Aerofoils? no idea. Trial and error I think is the phrase. You could always try it without first.
Cheers,
She flies!
I mounted the battery further back to get the CofG right as per the plans and then my Dad threw it up into a windy Lincolnshire afternoon.
It went vertical immediately (as I'd launched on up-elevator) then stalled about 50 feet up, rolled over and headed for the deck. I caught it and send it screaming off in an open circuit. Tried to build some height and it went vertical again, this time it stalled and I had to barrel roll on the recovery to get it shiny side up.
I kept it at half stick and it flew nice and steady, but I was too nervous to try any controls as it was too low and flying in-between a two rows of trees. I decided enough was enough and I let it drop into the long grass - the first time in my life I've performed a controlled and level landing away from a heli!
The wing tip broke and the motor mount gave up when the prop hit the floor but basically it's fine.
I was buzzing. It's so unbelievably responsive. Makes my cessna feel like a blimp! Can't wait to repair and have another go!
Totally exillerated!
I mounted the battery further back to get the CofG right as per the plans and then my Dad threw it up into a windy Lincolnshire afternoon.
It went vertical immediately (as I'd launched on up-elevator) then stalled about 50 feet up, rolled over and headed for the deck. I caught it and send it screaming off in an open circuit. Tried to build some height and it went vertical again, this time it stalled and I had to barrel roll on the recovery to get it shiny side up.
I kept it at half stick and it flew nice and steady, but I was too nervous to try any controls as it was too low and flying in-between a two rows of trees. I decided enough was enough and I let it drop into the long grass - the first time in my life I've performed a controlled and level landing away from a heli!
The wing tip broke and the motor mount gave up when the prop hit the floor but basically it's fine.
I was buzzing. It's so unbelievably responsive. Makes my cessna feel like a blimp! Can't wait to repair and have another go!
Totally exillerated!
_Al_ said:
She flies!
I mounted the battery further back to get the CofG right as per the plans and then my Dad threw it up into a windy Lincolnshire afternoon.
It went vertical immediately (as I'd launched on up-elevator) then stalled about 50 feet up, rolled over and headed for the deck. I caught it and send it screaming off in an open circuit. Tried to build some height and it went vertical again, this time it stalled and I had to barrel roll on the recovery to get it shiny side up.
I kept it at half stick and it flew nice and steady, but I was too nervous to try any controls as it was too low and flying in-between a two rows of trees. I decided enough was enough and I let it drop into the long grass - the first time in my life I've performed a controlled and level landing away from a heli!
The wing tip broke and the motor mount gave up when the prop hit the floor but basically it's fine.
I was buzzing. It's so unbelievably responsive. Makes my cessna feel like a blimp! Can't wait to repair and have another go!
Totally exillerated!
Great!I mounted the battery further back to get the CofG right as per the plans and then my Dad threw it up into a windy Lincolnshire afternoon.
It went vertical immediately (as I'd launched on up-elevator) then stalled about 50 feet up, rolled over and headed for the deck. I caught it and send it screaming off in an open circuit. Tried to build some height and it went vertical again, this time it stalled and I had to barrel roll on the recovery to get it shiny side up.
I kept it at half stick and it flew nice and steady, but I was too nervous to try any controls as it was too low and flying in-between a two rows of trees. I decided enough was enough and I let it drop into the long grass - the first time in my life I've performed a controlled and level landing away from a heli!
The wing tip broke and the motor mount gave up when the prop hit the floor but basically it's fine.
I was buzzing. It's so unbelievably responsive. Makes my cessna feel like a blimp! Can't wait to repair and have another go!
Totally exillerated!
Sounds like you need to program some rates into the controls (or some exponential). Alternatively, if you can, put the control rod on the hole nearest the servo centre, and furthest from the hinge line on the control surface. This should reduce the amount the surfaces move relative to the stick and make it less sensitive to your inputs.
Cheers,
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