SE5a Full Fuselage 3D Maiden report - Page 3 - RC Groups
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Jun 26, 2007, 09:36 AM
Brit in Bahrain
Nigelp's Avatar
Wings & Struts:

The wings themselves are easy – flat plates – just cut out. When I first looked at the drawings I thought – Peter has left out the spars – so I emailed him to correct the mistake. He replied that there were no spars and that all of the loads were taken by the struts and the flying wires. He stated there was no wing bend, even with vicious blender manoeuvers !!!!! (I won’t say I didn’t believe it but I was decidedly skeptical……..Not any more – I have been astounded - you don’t need them ! – and believe me – Peter really throws his planes around – just look at the video on his SU-26MX 3D thread !!!!!

I glued the 3mm balsa to the wing strut locations, top & bottom wing – but I did not make the slots or the cuts for the plywood flying wire anchorages – nor did I make the anchorages – just left them blank. (Peter’s struts and flying wire anchorages are ingenious so if you want to go that route – no problem) On the underside of the top wing I cut and glued a wider balsa plate to allow for my modification of ‘splayed’ cabine struts. (use Peters fore & aft measurements, just space them equi-distant – further apart.)

On all of the wing & cabine strut balsa plates I just marked the centres of the strut positions and then drilled holes at these locations to fit my secret weapons – Bamboo chopsticks (gpw on this forum discovered them years ago – I’m a bit slow and only just caught up !) They are an aerodynamic shape – look about scale, have got a taper at one end – so you only have to taper the other end, they are strong and best of all – cheap ! I just cut them to length, and tapered the end.

After masking & painting the wings I attached the bottom wing to the fuz, making absolutely sure that the distance from each wingtip to a point on the centerline of the fuz at the tail was exactly the same – so I knew they were square to the fuselage.

The top wing is up in the air – supported only by the struts and flying wires….To make sure that it was exactly at the right height, parallel and square to the lower wing – I cut some jigs (out of scrap 6mm Depron foam – I have lots of it LOL!) The jigs fitted over the lower wing and the upper wing sat in them – no way could the wings be out of line. They also made my life a lot easier when it came to fitting the struts.

With the jigs I was able to put the wing and cabine struts at the right angles into the lower wing – bit of 5 minute glue and bingo…..turn the whole lot over and do the same again ! (where the ‘splayed’ cabine struts go into the fuz – I just made pilot holes at roughly the right angles and then enlarged them with the sharp end of a barbeque skewer (lots of ‘meat’ under there) – then put some 5 minute epoxy on the ends of the ‘slightly sharpened’ chopsticks – and pushed them in.)

For the flying wires, as there are no model shops (or fishing tackle shops) within a few thousand miles – I decided to use 0.5mm / 0.019” diameter carbon fibre rod. Keeping the wings on the jigs it was just a case of measuring – cutting to size, making a hole in the balsa and Depron underneath, adding 5 minute epoxy and gluing them in. So far they seem very strong and no adjustment needed.

In retrospect (it’s that 20/20 hindsight again !) next time I think I would use the eyes of fishing hooks, epoxied or CA’d & bound to plywood for the wire anchorages – it might even be possible to drill the struts and insert the hooks direct ? (needs mulling over !) Braid (non – stretch) fishing line for the wires and probably not even bother with an adjustment mechanism – just use the KISS principle – if they stretch, cut them off and rig a new one ?

Once the wires were in it was time to hinge the rudder, elevator & ailerons. Because I was going to use pull/pull for the back end & torque rods for the ailerons I needed hinges (I normally use tape hinges) I knife edged the ailerons / rudder / elevator at 45 deg. and then made the hinges out of floppy disc material, sanded them, cut to shape and then made some holes with a pin to allow the glue to get a good grip…..It worked a treat – but – I used the Dubro Park flyer’ torque rods for the ailerons – they were way too flexible – being only approximately 0.7mm/0.03” diameter wire. That meant I had to cut the torque rods out and make my own using 1.5mm / 0.06” music wire and a ball point pen plastic inner for a bearing, and refit them – works a treat !

Next: The undercarriage
Last edited by Nigelp; Apr 09, 2008 at 03:15 PM.
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Jun 26, 2007, 12:43 PM
My plans are in my blog
Rusty-Gunn's Avatar
This is a very nice plane!
Jun 26, 2007, 05:17 PM
Team FlightPower AUS
pmjass's Avatar
The SE5A is as just as agile as the Sukhoi (see video link above) although it will fly a lot slower due to its much lower wing loading. It is a little easier to hover and harrier ; although when you fly it, low, slow and close gives the most satisfaction. I'm pretty sure the real SE5A's didn't quite have enough thrust:weight to hover anyway, LOL. I like to knife edge every now and then and to be honest it is a bit of a struggle to keep the SE5A on its side and running straight.
In summary I would describe the Sukhoi as mild to very wild while the SE5A is very mild to wild. (Mild as in a pussycat to fly, soft easy mushy stall and slow flying, wild as in able to loop up its own tail, roll in a twinkle and >1:1 Thrust to Weight)

Hopefully we can get some built and get a few videos posted.

Team FLightPower Australia
Jun 27, 2007, 02:09 AM
Brit in Bahrain
Nigelp's Avatar
The undercarriage:

Peter drew up a ply plate which fitted vertically up into a slot in the fuselage. After drilling some holes the u/c legs could be glued and bound to the plate.

This is perfectly serviceable and works well, but, with the combination of my flying (or more accurately) my ‘landing’ skills (LOL) and rough dessert terrain (if you miss the landing strip (narrow road !) I thought an undercarriage that would ‘knock off’ in the event of a bad landing would be safer and easier to repair.

After some thought I came up with……Bamboo chopsticks (surprise, surprise !!!!!! ) plus a bit of music wire, four bits of plastic cut from a milk bottle, 8 servo mounting screws and a bit of carbon fibre rod for the axle.

It’s a bit of a pain drilling the holes but I only got my own finger once (LOL) ! The result seems very strong and relatively light. (I have tested it – for real - inadvertently !!!!! – with TWO deadstick landings – it didn’t collapse !) To mount it on the fuselage I installed a ply plate for the forward end to screw to. Given that these aircraft tip on their noses quite easily – I cheated and installed the front of the u/c underneath the leading edge of the top wing which is far enough forward of the centre of gravity to avoid nose tipping. (the ‘scale’ u/c position is with the front vertical leg directly underneath the front cabine strut !) A rear ply plate is let into the wing at the point where the rear crossbar touches.

I think the photographs are self explanatory but if you have any questions – ask away !

Next: Lewis Gun & finishing up…..
Jun 27, 2007, 10:15 AM
Brit in Bahrain
Nigelp's Avatar
Finishing up:

I decided the plane didn’t look right without a Lewis gun on the top of the wing (it’s a mark of the SE5a IMHO) – so I made one…..3mm Depron for the body and ammo drum, toothpicks for the barrel & spring holder and cardboard / toothpicks for the rear handle and trigger guard.

I just cut the mount out of 3mm Depron, painted it mat black and glued it to the wing, then glued the gun on top. (I was going to extend the mount in a curve down to just in front of the pilot – as per the real thing – but finally decided that as this was not a scale build – what I had was good enough and enhances the appearance without really going to town.) As a bonus – I found that even if you tip it upside down resting on the nose and upper wing for maintenance – the barrel of the gun doesn’t quite touch the ground.

The throws were just ‘copied’ on the computer TX from the Big Baron (pmjass - Fokker Dr1) On low rates:
Aileron 1/4” each way
Rudder 5/8” each way
Elevator 3/4 ” each way
High rates were double the low rate settings – and as I said previously – scared me to death !!!!! (I’m not that good !).

As is my wont (sport flier and all that) I always start with the C of G at 25%. For those of you who are not sure how to work out the C of G on a straight winged biplane (swept back wings are a little more complicated !) – just measure from the leading edge of the front wing to the trailing edge of the rear wing (use two set squares) – then calculate the percentage you require as if it were a single chord – in this case 25%. This gives you…mild. As you move the C of G further back it starts to get more and more responsive ! (I always mark 25%, 30% and 33% - 33% is wild !!!!)

I used another tip I picked up on this forum….once I had found and marked the C of G positions – underneath the upper wing on either side of the cabine struts – I used a hot glue gun and put a ‘blob’ of glue at each location. Once this is done it is easy to just pick it up and check by putting the forefingers on the blobs and seeing how she balances…..KISS again, simple but effective.

Even using a heavy 3S 1900 mAh lipo battery and a forward mounted u/c I still had difficulty in getting the C of G that far forward…..(the 3D’ers among you won’t have that problem - LOL) I ended up with the esc, battery and servos in the ‘battery’ compartment and only the receiver in the rear hatchway.

For the aerial I used an Azzar Micro lite antenna (about 9” long) it’s front loaded and means I can finally fly aircraft without an aerial wire hanging out of the back ! I literally can’t tell the difference in range between the Azzar and the standard aerial wire, but I have noticed that the Azzar will not ‘cure’ a poor receiver. If the receiver glitched periodically with a standard aerial it will glitch with an Azzar – no better and no worse - just the same. (assuming of course that it is the receiver and not a poor installation !?) I now try, wherever possible to use Schultze, German receivers – only single conversion and (relatively!?) expensive, but superb and noticeably (IMHO) better than the Multiplex & FMA dual conversion receivers that I also own.

The aircraft flew well (my style) with the forward C of G and low throws….but, as you know, I had ESC problems – overheating (albeit in extremely high air temperatures of 112 F +) …..well, I did some checks last night and found that my ESC is well and truly cooked !!!!!! (funeral march at this point) To try and ensure that this does not happen to the replacement I have arranged for a ‘cooling hole’ in the nose and an air outlet on the rear underside to ensure a good cooling airflow – I may also install a cardboard air deflector inside the battery compartment to ensure that all of the air from the ‘hole’ goes over the ESC.

I think the pictures show the new cooling arrangements quite well.

As soon as I get the plane back in the air my next move will be to get my first ever video using my new sexy helmet camera ! (that should be a laugh – been playing with parallax !!!!!!) plus a 3D model being flown sedately !!!!!

Many thanks to Peter (pmjass) for a really fine design which I thoroughly enjoyed building.

Happy landings,


p.s. If there is anything in the build that is not clear or needs to be expanded – please let me know and I will try and answer your questions.
Last edited by Nigelp; Jun 27, 2007 at 12:41 PM.
Jun 27, 2007, 11:33 AM
Registered User
kdahlhaus's Avatar
Thanks Nigel for taking the time to post the build thread and photos.

Which plane do you enjoy flying the most - the SE5a or the original DR1 Big Baron ( or even the Baby Baron)? Would you recommend any particular one of these over the others? -- I know 'build them all' is probably coming!
Jun 27, 2007, 12:13 PM
Brit in Bahrain
Nigelp's Avatar
Hi kdahlhaus,

Thanks for your reply, I have enjoyed doing the build thread - just hope it gave you guys some ideas and repaid in some small way all the help, tips, ideas, felowship, laughs, advice and enjoyment I have gained from the great individuals who populate this forum.

In terms of which plane I have enjoyed flying the most - I would have to say it is the Dr1 Big Baron. That is a quick build / looks good / superb flyer / doesn't mind a bit of wind / totally aerobatic and lands like it has a parachute attached - it's a real joy !!!!!!

The SE5a full fuz is without doubt the best 'looking' plane but as yet I haven't flown it enough, yet, to form a solid opinion - ask me the same question in 3 months time.

Happy landings,

Last edited by Nigelp; Jun 27, 2007 at 12:22 PM.
Jun 27, 2007, 01:11 PM
Registered User
kdahlhaus's Avatar
I was hoping you'd say the Big Baron. Hope to build it at some point here.
Jun 27, 2007, 07:35 PM
building building building!
aerophilia's Avatar
Hi Nigel, I've been following your build log for the last few days. Thanks mate, excellent descriptions and pictures. Bought myself some chopsticks today. Can't wait to get building, once I've finished the spitfire! Great work and looking forward to the video.

Cheers, A.
Jun 28, 2007, 09:24 AM
Brit in Bahrain
Nigelp's Avatar

Thanks for your enthusiasm and encouragement. Love to see photies of the Spitfire when it's finished !

Jun 28, 2007, 09:45 AM
Registered User
critterhunter's Avatar
Here's my SE5A early stages using EPS foam for the wings and fuse (2" thick fuse). All thrown together with toothpicks for a quick photo. For the most part the plane is pretty much scale, though using my bucket of apples math skills probably has a few things a little off. I lengthened the nose a good bit to insure being able to get COG right. The verticle stab/rudder looks too small so I think I need to break out the bucket of apples and re-do the math. The wings are 36" Clark-Ys for now. Not sure if I'll change those to the proper airfoil or just try them. Anybody have any idea if bamboo skewers will be enough for wing struts or must I go balsa? The ones in the photo are just put there to hold the wing up for the picture. Motor will either be a re-wound BP21 or a 2409-12.

Nothing sanded yet, just rough cuts...
Jun 28, 2007, 10:02 AM
Brit in Bahrain
Nigelp's Avatar
Hi critterhunter,

Looks good. Haven't tried EPS foam yet but I would definitely use some balsa plates to put the struts into - just to give them a bit more to grab on to - I would also seriously think about using chopsticks rather than barbeque skewers (if you want a 'scalish' effect) IMHO the skewers are just a bit too spindly for that size wingspan.

So of the guys may have some better ideas?

Let us know how it goes.

Jun 28, 2007, 11:25 AM
Registered User
critterhunter's Avatar
Thanks for the tips. I also need to know how to figure out where the wings should go and what measurement to use to stagger them? Well, I think I can rough guess wing placement on the body based on my measurements from a print I have laying around, but I'm still not sure. Put it this way, if I stick with these two 7" wide wings what should be the distance between the one and the other's edges? While I'm at it, is there any wing incedense built into the stock plane? At the moment I'm just planning on mounting them flat. Also could use a way to figure out where COG should be. Currently the fuse is 39" long, I believe. This is my first bipe and, since I don't really have any true planes for this 36" wing upscaled version, I'm pretty much winging it as I go.
Jun 28, 2007, 12:01 PM
Brit in Bahrain
Nigelp's Avatar
Hi critterhunter,

If you have a scale type drawing or 3 view - I would just measure the ANGLE of the stagger i.e. Draw a line from the tailplane forward to the wigs - use that line as your datum, then draw a line through both leading edges. Once you have that angle (you don't even need to measure it - just use a piece of paper !) then extend the line upwards - match it against your model and now you know the line on which the leading edge of the top wing should be - now measure up the line the same distance as your vertical wing spread and make a mark on the line - that is exactly where your leading edge should be. (the drawing attached may help you to visualise this.)

If your wings are just flat plates - I would go with ZERO wing incidence (same as the 'Big Baron' and this SE5a) i.e. Wings and tailplane all on the same line - parallel to each other. Again, some of the guys on this forum may have different ideas ?

If you look at the 'Finishing up' post on this thread I explain exactly how to find the C of G with a biplane (start at 25%)

Hope this helps,
Good luck,

Last edited by Nigelp; Jun 28, 2007 at 01:12 PM.
Jun 28, 2007, 02:17 PM
Registered User
critterhunter's Avatar
Thanks for that info. I printed it (and your message) out for reference. A friend is coming over tonight that has more experience at building bipes (this is my first one) and he's going to walk me through figuring these questions out. I'll show him this thread. Thanks again...

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