Scratch Built SE5a

[Geoff S]

On field assembly is certainly the main drawback for biplanes.  However, My DB Gypsy/Cirrus Moth (as seen in my icon) is quite quick and looks quite scale in flight though nothing as detailed as Greyhead's beutiful SE5a.  Boddo devised a simple method of attaching the interplane struts which I've adapted for my Flair SE5a to replace the 8 nuts and bolts which were a bit of a pain.

 

 

This was the maiden flight before I fitted dummy (elastic) flying and landing wires.  The interplane struts are held to the top wing with 14 gauge bike spoke fed through split cotter eyes and held in place with a rubber band - quick and simple for a sport-scale builder like me 🙂

 

However, biplanes remain my favourites even though they get flown less frequently than my simpler airframes.

Edited May 5, 2023 by Geoff S

[Greyhead46]

Hello Geoff

 

Nice model! His designs are always good, the sports models fly perfectly and the "scale" designs are a good compromise between scale and flyability. I've seen some detailed-up and they look great. The same goes for Flair of course.

 

Grahame

 

Well summer has arrived, at least for today! That gave me something of a dilemma, should I go flying to get some thumb practice, or assemble the SE5a and take some “good” outdoor shots. I decided on the latter, which was the right decision as it turned out because the wind ended up quite strong; the streamers on the interplane struts were blown horizontal.

To assemble the model actually took 20 minutes, not too bad, but longer than I thought it would be. I have only done it a few times and I’m sure I will get quicker with practice; I did make a couple of mistakes which meant I had to reverse a bit.

The photos have turned out well; the only problem was the “giant” dandelions, which I’ve removed with the PhotoShop clone tool. I’m no expert when it comes to photo manipulation but so long as you don’t zoom in too close the overall effect is OK.

 

I think the hangers in the background really add to the photos, hope you agree.

 

I’m getting to quite like this photo manipulation! On this one I’ve also removed the grass overlapping the wheels, which gave the game away somewhat.

 

 

A black and white “grainy” photo more like WW1.

 

 

When I checked I found that I hadn’t in fact got a photo of the finished cockpit so I took a pilot’s eye view!

 

 

 

Edited May 7, 2023 by Greyhead46

[John Rickett 102]

This has been a fascinating thread to read and I congratulate you on the scale fidelity.

You mentioned right at the start that the model construction was actually some time ago, what scale/span did you settle on in the end and what was the final weight?

Did the Laser 70 live up to expectations as an adequate power source for the size of model?

Perhaps I'm jumping the gun and this will all be covered later..........     

[Manish Chandrayan]

Beautiful work 👍

[Greyhead46]

Hello John and Manish

 

Thanks for the replies, always nice to know you're enjoying reading the thread.

 

This post is all writing, no photos, it has the dimensions you wanted John but don't rush with the 16x4 prop!

 

Grahame

 

 

At long last the strong winds we’ve been having weren’t in evidence so I managed to get the SE5a out to the flying field.

First a range check, then another with the engine running, everything worked fine, so out to the takeoff area, a quick check of the controls and “wow” the elevator’s reversed, back to the pits for a spot of transmitter programming. After all the time I’ve spent setting up the model it just goes to show, never take anything for granted. A certain disaster averted!!

With everything now moving in the right direction it’s back out for another attempt. As I eased open the throttle the model started moving forwards but very sluggishly; half way down the runway and the tail still hadn’t lifted so I closed the throttle. Surprisingly the model carried on and eventually bumped over the “rough stuff”. When I collected the model one of the landing wire brackets had broken; I felt sure it must have been fractured, or at least badly stressed, when I was making it as the ground wasn’t that rough.

No chance of a flight now but I thought I might as well do some more testing, I removed the cowl and tweaked the needle valve for maximum noise and tried a takeoff run again; this time it was a lot better with the tail lifting OK.

I have been a little concerned that my “standard” 13x6 prop looks very small against the large radiator with only a couple of inches of blade protruding into clear air so I fitted the “jumbo” 16x4 and tried again.

This time the acceleration was much better, in fact the tail was up in about a yard and before I knew it the model was a couple of feet in the air. I now had to make a quick decision, keep power on and risk a flight or reduce power and land? Common sense prevailed and I decided on the latter; luckily our mown square at Redmarshall is a good size, even so it was a bit of a bumpy landing but at least this confirmed my suspicions about the landing wire bracket having been weakened as the remaining brackets handled this severe “landing” with no problems.

The bracket was easy enough to repair; I’ve used tinplate this time instead of brass so it should be even stronger. The next fine day and I’ll try again.

I was a little disappointed to not actually get a flight but with a model of this complexity it’s not uncommon to not get off the ground on the first attempt, at least I managed a bit of air under the wings, even if inadvertently!

 

The Se5a had its first “real” flight 2 weeks later; the flight wasn’t without its problems, but it flew well and looked good.

There’s nothing major that needs doing but as always seems to happen with my models the first flights highlight a few things that need some work.

The 14Ba bolts used to secure the landing wires just aren’t strong enough, at least one has sheared off at every landing so I’m in the process of replacing them with solid pins. I don’t want to make them too strong, as I’d prefer them to shear off on a heavy landing rather than over-stress the airframe.

My previous SE5a had very poor aileron response, and a Flair “scout” flown by another club member is the same; therefore I had set this model up with quite a large amount of aileron deflection. I don’t know if it’s because I’ve used the scale aerofoil section this time or that the gap between the wing and aileron is shrouded but this model certainly doesn’t suffer from poor aileron response. The flight was very “exciting” until I switched to ½ rates!

It is also quite sensitive on elevator despite the CG being at the forward limit. I had controlled the elevators using separate servos on separate channels slaved together, the elevator and spoiler channels. Unfortunately this made the elevator trim only move one elevator, meaning that the spoiler knob had to be used as the trim control, this proved to be too coarse and I couldn’t trim for level flight. Before I left for my holiday I ordered a “Y” lead with servo reverse and have now fitted that so the elevator trim works as normal now.

The ground handling was pretty good so I decided against fitting a gyro but I have bent the axle to impart a few degrees of toe-in, a lot cheaper!! I’ll let you know how well or other wise it works if we ever get some decent flying weather.

Here’s some information that may help.

Wing span 58 in.

Wing area 1220 in²

Weight 9¼ lb.

Prop 16 in. dia x 4 in. pitch

Static revs. 6800 r.p.m.

Of course I don’t know the all-important figures for lift, airspeed and drag, which you really need to do any meaningful calculations. All I can say is that there is sufficient lift at what appeared to be a ”scale” airspeed and the large diameter low pitch prop turning at fairly low revs overcame the drag much better than the 13 x 6 prop at higher revs.

[Greyhead46]

The theoretical top speed for my SE5a using the 16x4 prop is 26mph, this gave me some concerns, however, looking at a ”typical circuit” eased those concerns somewhat.



At 18% scale the speeds would be:

Take off: not below 9mph

Climb out: 10.8mph

Level flight: 14.4mph

Touchdown: 8.1mph

The maximum speed is given as 123mph, it doesn’t say if this was obtainable on engine power alone but somehow I imagine this was the absolute maximum speed the airframe could withstand before the wings ripped themselves off or something equally terminal happened! At “scale” speed this equates to 22.14mph so my theoretical top speed of 26mph sounds reasonable.

Of course the theoretical top speed doesn’t take into account the drag factor and models always seem to fly faster than “scale” speed but in practice it has worked out OK so I’m happy to stick with the large prop even if it does mean that the engine is somewhat “over-propped”.

[John Rickett 102]

I was surprised to learn that its 18% scale, throughout the build thread I had assumed it was at least 20%.  

I’m even more impressed you have been able to make all that detail at such a small scale. That’s not meant to sound disparaging, far from it, from my limited experience the smaller the scale the harder it is to create realistic detail, so well done.

Inevitably all the additions were going to have a weight penalty but if you are happy with the scale performance, you’ve achieved a hard to reach goal, so again well done.   

[Greyhead46]

Hello John

 

Thank you for the compliments, much appreciated and you're correct the smaller the scale the harder it is to detail convincingly but I 've never built "big" always as small as I can to fit the Laser in. Of course a non standard scale means few commercially available accessories which only adds to the fun!

 

Biplanes have loads of wing area for lift but also loads of drag to overcome so you need a more powerful engine to fly at any given speed, more of that in this post.

 

Grahame

 

Just got some more information; the maximum speed with the 200h.p. Wolsey Viper was 138 mph so obviously they didn’t fall apart at 123 mph! At 18% that still works out OK for my model at just under 25 mph. not that I really want to fly at maximum speed, I prefer low slow passes!

Once again no photos, can't fly and use camera at the same time!

 

On the last trip to the field it was a flat calm, very unusual for our Redmarshall site.

As expected the take off run was considerably longer than on previous occasions, although the grass is kept short, at scale it is still the equivalent of taking off in a field of mowing grass so there is plenty of rolling resistance. If the model is taking off into a 5 mph wind then the airspeed is 5 mph faster than the ground speed; it even has an air speed of 5 mph when standing still!

What did surprise me was the rate of climb, or lack of it, once the model left the ground. In fact by the time it had gained sufficient height to make a turn I was quite concerned that it was so far away that orientation would soon become a problem. This is where I made an “error of judgement”; I turned the model to the right. The model lost some height executing the turn and was now only just visible above the hedge line, then I realised in the direction the model was now travelling the ground was rising at a gradient about the same as the models rate of climb so there was insufficient height to make another turn, so I closed the throttle and set the model down in the middle of the barley field.

When I got the model back I tried adjusting the needle valve just in case the engine wasn’t quite “on song” but it had no effect. I tried again; this time I was better prepared and had a successful flight but I’m going to try a smaller diameter prop to increase the engine revs, hence the maximum air speed, because although the model flies OK it is obviously marginal.

I’ve ordered an APC 15x4 but I’m going away in the caravan for a week so it’ll be after that before I can test it; watch this space!

 

My 123 mph maximum speed for an SE5a is way too slow. Information I’ve received suggests that they could in fact reach 225 mph safely in a dive, I say safely because presumably the pilots survived to tell the tale! I have realised where I made the error; I was quoting from an article about the Shuttleworth restored SE5a and the 123 mph must be the maximum speed that this is allowed to fly at these days, obviously they’re going to be very, very careful with such a valuable machine. I assume that the take off and landing speeds are still comparable to WW1 days.

 

[Greyhead46]

Just to bring you up to date on a couple of modifications to the SE5a.

I had bent the axle to give a few degrees of toe-in. It did improve the tracking initially but because of an unforeseen flaw in the design I’ve now straightened the axle again.

The axle passes through holes in the undercarriage legs and is held by bungee cords. Having bent the axle it was slightly “V” shaped and was positioned in contact with the base of the axle fairing with the apex of the “V” pointing to the rear to give toe-in. When I checked after a couple of flights the axle had rotated, the “V” was now pointing forwards, giving toe-out, exactly what I didn’t want! Presumably the friction in the wheel bearings produced enough torque to overcome the friction of the bungee cords, the ground handling wasn’t too bad before, especially for a model of this type, so I decided to abandon the idea.

I moulded the noses of the bombs from rubber both for safety and to make them less prone to damage; however, the rubber I used has proven to be very susceptible to the effects of fuel / exhaust emissions, the detailing has virtually melted away and they are very sticky.

I have replaced them with some dome shaped rubber feet from Maplin Electronics, they are made from much more robust rubber so I hope they will not suffer the same fate.

 

As you can see from the photo the new noses are not the correct shape, are slightly too small in diameter and have no detailing but you have to be pragmatic about these things.

 

 

I think they are quite acceptable especially with the arming vanes in place and when seen from a distance slung under the model.

 

[Geoff S]

A regular poster (PDR -a very knowledgeable chap) on the old RCMF site advocated toe out on undercarriages rather than toe-in.  His reasoning was that as a model veered left (say) then weight would tend to be transferred to the outer/right wheel, which, if it were toed-in would exacerbate the left veer.  However, if the wheels toe out, the transfer of weight to the opposite wheel would result in the model tending to straighten. So perhaps your unintentional toe-out might be just what you need?

 

[Greyhead46]

Hello Geoff

 

I don't know but the automotive industry have used toe-in "for ever" to help cars track but of course cars don't have wings producing lift?

 

I'll stick at neutral for now!

 

Grahame

 

 

Well I’ve had the 15x4 prop for a couple of weeks now and have tested it out on the ground; the 1-inch reduction in diameter has resulted in a 16% increase in static revs to 7900, which should help considerably in a “no wind” situation.

I waited before posting this in the hope of being in a position to also give a report on the practical difference to the flying but with the weather being as it is there’s been no chance of that!

I also doubt if I’ll be doing anymore flying before the end of the season because we have just sold our house and are in the process of packing everything into boxes ready for the move. I think you’ll agree that packing the better half’s china is one thing but packing scale models and all the associated modelling tools requires far more care and attention!

And that is where the original thread ended back in 2009 apart from some more detailed explanations of a few of the detailing techniques that were asked for.

 

It was not a simple house move, in fact we had bought a 5 acre field and over the previous 2 years as well as building the SE5a I had drawn up plans and written business plans etc. for the development of a caravan site (Woodside Ridge) and Durham County Council eventually agreed planning permission. A combination of development work and health issues meant no modelling until 2019.

 

I dug out the AcroWot, bought some fuel, of course the Laser fired up first touch of the starter and never missed a beat and I headed out to Redmarshall. Just like riding a bike it all came back, almost! I needed lots of “stick time” to get confidence and sharpen up my reations; and then came Covid!

 

During 2022 I got more confident, invested in a new electric glider so I could get to the field with less tackle and went 2.4Ghz. I’m just hoping for a better summer this year to hone my skills and who knows I might feel confident enough to get the Se5a out, but I’m not going to rush things, too much at stake. If I do I’ll be sure and update the thread.

 

Before I originally did this thread I had done one, not as comprehensive as this, about the construction and flying of a Parnell Elf. That too is no longer available free of charge so I think I might up load it to RCM&E, it’ll give me something to do until the flying season starts.
 

[stu knowles]

I have just caught up with your last few posts.  A lovely looking model which is a great credit to the builder.  I have to say that the thought of closed loop ailerons make me shudder, -  Lots of potential failure points like cable slipping off rollers etc, but If you have made it work, well done -  

[paul devereux]

This has been a great thread. Yes, another on the Elf build would be good! And get someone to video the SE5 when you get it flying!

[Paul De Tourtoulon]

Racing RC cars for a while, toe in makes it sensitive and toe out makes it more stable, but for a plane I would make them parallel.

[Greyhead46]

Thanks for the replies, the aileron control certainly makes the rigging a bit more awkward but has worked fine so far and if all goes to plan it may well get some more use this year. The ground handling is not too bad so I'll leave well enough alone but I've always got the ex Parnall Elf gyro in reserve.

 

I've just started a thread about the Parnall Elf, hope you all enjoy it.

 

Grahame

[Fitzy]

Hi in the very near future I will be starting to build a Belair 1/5 scale build and am following your posts on how you built yours. I have read much of what you have built and am really fascinated by how you do everything.  Thanks for your posts.  It truly looks amazing.

Cheers.

[Fitzy]

I hope I can access your site as I will be building a Belair SE5A in the near future. Thanks

[Fitzy]

Hi I am just beginning to build a 1/5 scale from Belair kits.  There is virtually no instructions so I am very interested in your build.

What scale is this?  I plan on using many of the tips and construction ideas that you show.

Thanks for posting this, it is much appreciated.

I love your detail.

Cheers

Jerry

[David Davis 2]

7 hours ago, Fitzy said:

Hi I am just beginning to build a 1/5 scale from Belair kits.  There is virtually no instructions so I am very interested in your build.

What scale is this?  I plan on using many of the tips and construction ideas that you show.

Thanks for posting this, it is much appreciated.

I love your detail.

Cheers

Jerry

 

In a post on 8th May 2023, Greyhead states that his SE5a is a 18% of the full size aircraft. Your Belair version will be a little larger.

[Greyhead46]

Hello Jerry

 

As I designed my SE5a from scratch I can’t really help with the actual construction, Belair should have sorted all that out for you! The only suggestion I can think of is the addition of thread braces as shown on pages 3 and 4, they add very little weight but add greatly to the stiffness of the rear fuselage and they look good when peering into the cockpit.

 

The finish detailing is a different matter so if there’s any process that I haven’t explained fully just ask and I’ll certainly do my best to clarify. I knew exactly what I’d done but trying to explain it is never easy.

 

Grahame

[Fitzy]

Thanks for the information.  It is appreciated.

 

[Steve Fox]

Hi WOW

A master class in scale building 

Bravo 👏 

Cheers Steve NZ 

[Greyhead46]

Hello Steve

 

Glad you enjoyed the thread!

 

Grahame