F1R build 2018

[Skymon]

My first F1R is now built, the thread wasn't that detailed in terms of build processes, I didn't feel that I have the experience to be able to publish a 'how to'.
My efforts to learn the new techniques are really just a record of my failures and lessons learnt.
I found a wealth of detail on the net with regards almost every process of the build and I had almost daily e-mail contact with Tony Hebb, Bob Bailey and Mark Benns who provided all of the coaching and advice anyone could need.

What did I learn building this little ship??

Covering
I found that my covering techniques improved massively. You need good frames to hold the film. Using water rather than spray adhesive to hold the film on the frame really helps. You can fiddle with the film to get exactly the tension you need. Using a twisted frame for prop blades means nicely covered blades. I modified my soldering iron to reduce the temperature and fitted a much thinner wire to allow me to manoeuvre it easily. I use a needle and a candle for the very fine prop blades.

Go lighter.
I found that built up props are pretty rigid little structures. I over built my early parts because of the fear of breakage. By the tie I built prop number three I had cut the mass in half by choosing smaller sizes. Prop spar wood need to be the best you can find.

Rolling balsa is easy
Rolling balsa was a piece of cake. It's all the other bits that come after that are a nightmare!
Removal of the wood after it's rolled and dried is not easy. Be very careful pulling that tissue about.
Cutting the join is extremely difficult - I need a jig for this in future, or I could attempt to cut the trip the correct width at the start.
Gluing the join is intense. Concentration is required at a massive level. Holding the join closed, gluing 10mm at a time, moving the wood on the form so it's doesn't stick, making sure the glue is set before doing the next section, not crushing the wood... so much to remember. But actually quite a simple process, just involved.

0.010" balsa tubes are fragile
I learnt that nothing is required to hold the rolled balsa on the form. Just the tension of the tissue and water will do it. Use ultra fine rubber and you will get ribs and indentations. Not a great finish...
The tube is VERY fragile, even picking it up off of the bench was fraught with danger. If you put it down, put it down on a couple of strips of balsa that hold it up for easy picking.
Alignment of the front and rear motor bearing and hook is not easy. Mine were no where near the same. I have no solution for this - maybe marking the tube, or a jig or sighting better...
I will leave a small stub behind the rear hook next time for the addition of the boom plug. This is probably not the lightest technique but I found the handling of the tub to insert the hook web and the gluing and alignment caused my tube to distort. It ended up egg shaped. I'd like a nice round end for the boom plug to fit in nicely and also if the plug goes around the hook then you need to slot it. I'd prefer not to have to do that.

Booms are hard
One of the toughest things was finding a boom tapered form. In the end I didn't. I made one from wood.
Despite my efforts the boom curved and bowed. I think this is due to the way the wood is cut to a taper - the grain is at different angles to the form around the circumference.
That thin end of the boom is slightly less strong than air. Look at it wrong and it breaks.
Add a plug in the end to attach a stab post to and the end comes unglued... I will use white glue next time.

VP hub wasn't too tricky to build
Just small and fiddly - I've not idea if it works, or how to adjust it, but the construction was pretty straight forward.

Bracing wire is fine, oh so fine...
Tape on the ends so you can find them. Don't forget it's there when you hold the plane. Glue instead of knot.

Flying is exciting
That feeling when you let it go, then catch it quick and adjust the stab to stop the death dive, then let it go, then adjust the prob blades to stop the wobble, then let it go again, then adjust the wing incidence to the kill that tiny stall, then let it go and it flies like a gossamer angel. Until it hits the wall. That's a great feeling.

That's a long and rambling lessons learnt section. I hope it provides some help to someone sometime.

I'm now embarking on a long program of lightweight upgrades, hoping to get two planes eventually and one for the UK 35cm class form the heavier stuff.

I can't wait to let this thing go somewhere with more room than my lounge.

I have to say, once again, that I am always astounded by the helpful advice and the freely given materials and tuition from this wonderful community.

S

[mkirda]

Another great beginner plane is the Mashup.

I believe the plans are in the gallery.

Indoor News and Views also has LeoP's F1D Jr. plan and that one also flies really well.

Regards.
Mike Kirda

[piecost]

Skymon,

I have enjoyed your build thread and found it useful to compare to my own experiences. I have only built one 35cm model, to Tony's plan so cannot claim to be an expert, but I'll list some pertinent comments.

My first model had a solid stick and I am building two new models using tubes. I bought an ali boom mandrel from Ray Harlan in the states. Also, his balsa stripper which I find useful. I printed out a paper template to the correct size for the tapered boom, I think that I didn't need to trim the seam prior to gluing IIRC.

I haven't assembled the components and am thinking of employing a detachable boom. Can you please elaborate on how you joined the detachable boom? Did you use a key to prevent the boom rotating?

I use vasaline to attach the film to the frame. I used a Cautery pen to trim the film. Powered by 2 AA batteries; it has the advantage of not  having a power lead to drag over the model.

I spent a lot of time constructing a motorstick & boom assembly jig (see attached photo)/ The prop bearing, rear hook, wing and tail posts are held in their correct positions realitive to the stick and boom. The downthrust is marked for attaching the prop hanger. I have a seperate jig for twisting the side-thrus on the prop hanger. The jigging took longer to build than a couple of whole models.

I used a similar set-up on my LPP models which resulted in the parts being truly interchangable. The tail setting angle required to trim different models made using the jig was nearly identical.


Tim

[Skymon]

Tim
I'd love some details on that jig!
Si

[Skymon]

Joining motor stick to boom...

I made a plug up from the motorstick wood.

This is an area that I learnt a lot.
I didn't make a very good job of it, especially as a removable joint.
So I glued it all solid.

The plane is small enough that I don't really need to break it down for storage.

I went wrong in a number of areas and would do things very differently the next time.
Essentially you make a sleeve that sits inside and the boom sits on one end and the stick on the other.
You fix the stick end. The boom end should be tapered so the boom will tighten up as it is slid on.

These suggestions might not be the 'correct' or best way of building, but it's what I'll do when I build the next one.
 If there are people with more experience that can explain better processes then I'm all ears


The motorstick - I ended mine at the length of the motor hook.
I think that was a mistake, I see F1D planes and they extend past the motor hook.
By having the hook right at the end I needed to slot my plug sleeve, that caused an issue as it became less solid.
I also distorted my motor tube when inserting the rear hook web so it ended up as a 0 shape and not a nice circular O.
So the plug had to be shaped to fit.
I also used a rubber band to hold my tissue wrapped balsa together - that introduced surface effects that were not nice.

So the end of my motorstick was untidy.

The plug was then even worse because of slitting it to fit around the hook web.
Then distorting it to shape to fit the motor stick it went an even weirder shape!

Ideally the plug needs to be parallel bore a the stick end and tapered at the boom end.
Or, if the insertion distance at the stick is minimal, could be tapered all the way.

I broke the end off of my boom, so I couldn't really trim it to the right diameter to fit the plug, so it was a little loose.
I ended up gluing it all with some very thinned cement.

The motorstick is the area I am least happy with
I really should do it again

I'll take some photos of the area and photograph the next one I build.

Lessons learnt to integrate in the next assembly:
1 - extend the stick 10mm aft of the rear hook.
2 - use a jig to make sure the rear hook web is inserted and fixed without distorting the motor stick.
3 - wrap both boom and stick ends with a few wraps of Kevlar to hold that end joint closed.
4 - build a specific form for the plug shape including parallel section and tapered end.
5 - don't use anything to wrap the tube with when drying.
6 - be a lot more careful with the boom little end.

I have some more wood on the way, so I'll be having another go soon.

Best regards
Simon

[Skymon]

Pretty duff picture of the plug before trimming.
You can see the whole end is out of shape.

[piecost]

Skymon,

Thanks for the description of the tube to boom joint. I will extend the tube as recommended. I think that I will key it as well.

Regarding the Jig; the fuselage is orientated on its side. Each piece rests on a carefully sized plinth of MDF. Everything should line up 1.000" above the jig surface if each component is is accurate to its nominal dimensions. I used a 7/32" mandrel and 0.013" thick balsa tube. Each plinth is made from one part carefully sanded to height laminated against a second which is slightly taller to form a lip against which the part sits; held in place by a rubber band.

The plinth for the prop hanger allows for the thickness of the web and is used to make the slot in the tube. The downthrust is marked and a wire threaded through the hanger is used as a guide for sanding the top of the web. Once the prop hanger is glue it acts to stop the motor tube rotating in the jig. The plinth for the hook can be marked and glued. They should
align.

The holes for the wing/tail posts are made by resting a pointed rod on the jig and spearing through both sides of the tube. All the posts should be in alignment

The rear end of the boom is left overlength and held by a sharpened dowl that can slide fore and aft. The plan is to trim the boom to length after the rear tail post is glued.

I haven't figured out how to attach the bracing wire in the jig yet. The plan is to have the jig on its side (fuselage vertical) attach the wire to the rear, thread onto the wing posts and dangle with a blob of Bluetac over the front bearing (to tension) before gluing. Does this sound feasible?


Tim

[piecost]

I am making slow progress on my own F1R/35cm model. The motorstick was made on a 5mm mandrel from 0.013" and the Boom from 0.0095" on a Ray Harlan taper. The nearly complete stick weighs about 0.220g and the boom 0.080g.

I decided to employ a removable boom and followed Skymon's advice and left some tube extending aft of the hook, but only 5mm. This was not very round as gluing to the web had distorted the tube. I trimmed the front end of the boom at a length that matched the outside diameter of the tube and made an 8mm long sleeve out of the offcut. Its' seem was cut and re-glued to fit inside the boom and a balsa disk was added to its back end to hold the round shape, which aided the tight fit of the boom as the non-round shape of the latter tended to grip the sleeve. However, it was only about 4mm long (less than 1 diameter) to plug the boom onto. I am not sure if this will be sufficient.

I have yet to add the bracing wire. Does anyone have advice for this? The type of knot or binding, glue, how to tension the wire? I employed an angled piece of wire sticking out the top of the tube rather than a loop of wire. I wonder if I will regret it?

[Skymon]

The second flight of my F1R.
https://youtu.be/zk3rLZBUYh8

[Skymon]

The journey continues
I flew my F1R for the first time at the UK Nats. I was pretty chuffed with its performance on a 1/3rd motor made from a random bit of .032” rubber I had in the box. The 2/3rds spacer was made from a scrap of balsa with a sweet wrapper foil wound around it for ballast.
Being very careful to avoid the ceiling I flew rather conservatively and managed a gentle 7 minutes 20 seconds. Translating that to a full motor gives 22 minutes, so for a maiden outing without hitting the roof, which was ok by me.
The plane suffered as a result of my naivety with the lighter models. The motor tube was crushed on the right side by my fingers when loading the rubber motors. On return home I spent a couple of hours fixing that little issue by removing the nose cap, reshaping the tube and adding a small 0.010” web across from bearing to side wall. I then replaced the cap but made sure the grain was horizontal and not vertical. I also found that the leading wing and stab post tubes were stuck to the posts.
So those needed soaking and cutting off, I took the opportunity to slim the posts a little as well.
I was very happy that my plane was now ship shape and looking good, ready for my next session.

I had a little look at the weight sheet for the plane and compared it to the results others had published in various F1R plans.
Now I had a handle on the relative fragility of the F1R and had made one fly, I wanted to make it better.
Like a chunky bride-to-be, I decided I needed to start on a weight reduction program.
Looking at my plan parts mass table, the fuselage held the most room for improvement.

I decided to make a new boom first as it’s the least complex part in the airframe. I’d then move on to a new motor stick when buoyed with enthusiasm from my awesome new, superlight boom.

[Skymon]

A table of my targets..

[Skymon]

The new boom!
Boom; length 250mm, internal tapering from Ø5.0mm to Ø2.0mm. 0.008” 4.5lb C grain wood.
Blank is 250mm long 17mm to 7.5mm, cut the taper 4.75mm from both sides, not just one.
Stab posts; 15mm long, 1.2mm diameter. 4.5lb wood. Small end plug from rohacell foam Ø2.5, 2mm long.
   
Tapered blank calculations:

Big end
Inner diameter is 5mm, wall thickness is 0.203mm. Total outer diameter is Ø5.4064.
Circumference is equal to πd and d is 5.4064. The total circumference for the big end is 16.98mm

Small end
Inner diameter is 2mm, wall thickness is 0.203mm. Total outer diameter is Ø2.4064.
Circumference is equal to πd and d is 2.4064. The total circumference for the small end is 7.56mm

Target mass is 0.050mg

When I had finished, the new booms are significantly lighter than the previous one.
They came in under my target weight reasonably easily.
I found the construction easier this time and have created some nice neat parts.

[piecost]

Simon, thanks for posting the weights. That will give me something to aim for when i start on my model again. Does the last picture show depron end caps? Is this part of a construction jig? Also, what diameter and density tail posts are you using?

[Olbill]

Minor detail: To convert 1/3 motor flight time to projected full motor you have to restrict the max altitude to 1/3 of the ceiling height.

[Tapio Linkosalo]

Or you need to make the full motor flights in a hall 3 times as high!

[Skymon]

Yes, you are correct!
Regarding 1/3rd motor flights.
It's something that only just clicked with me last week.
I was pondering the portion of the hysteresis curve above my climb torque and it was a three times as long... (strangely enough  )
It then clicked that I'd be through the roof by the end of it.

I have some work to do with regards rubber.

I have made progress on the motor stick now and it's all good with regards weights.
I will be fitting my wing posts tonight, straight after I found out who wins Bake off!

Si

[Skymon]

Simon, thanks for posting the weights. That will give me something to aim for when i start on my model again. Does the last picture show depron end caps? Is this part of a construction jig? Also, what diameter and density tail posts are you using?

It's a little bit of Rohacel.
I guess XPS could be used too, but it would melt with any touch of Acetone.
PMI seems to resist it.
I could of used a bit of superlight balsa too.


Tail posts were 1.2mm diameter and made from 5lb wood.
regards

[Skymon]

The new motor stick
Stick; length 225mm, built on a Ø5.0mm former, 0.0095” 4.5lb C grain wood.
Taper last 10mm to Ø4.8mm by removing 0.1mm from each side and 0.2mm from centre
Wing posts; 75mm long, Ø1.2mm. 5lb wood.
Add bracing wire wedges to posts 25mm up.
Rear hook; 0.008” wire.
Prop bearing 0.009” wire pigtail.
Both on 0.008” 5lb A grain webs.
Braced with 0.001” tungsten wire or spectra fibre from bow string.

Find overall outer diameter
Inner diameter is 5mm, wall thickness is 0.2413mm. Total outer diameter is Ø5.4826.
Circumference is equal to πd. In this case d is 5.4064mm.
The total circumference is 17.22mm.

A 0.0080” blank needs to be 235mm long and 16.98 wide.
A 0.0095” blank needs to be 235mm long and 17.22 wide.
A 0.0100” blank needs to be 235mm long and 17.30 wide.

The last 10mm needs to be marked and then cut to allow it to be formed in to a taper to accept the boom.
For the wingposts I use quite heavy 5lb wood. I like the posts to be stiff. I started out with 75mm long posts and I have reduced those to 70mm to save a little bit of mass.
I trim to size and then sand round. When I have reached a good size along the length I soak the posts in hot water to puff them up again after all that sanding.
I then use a finer grit and sand again. I find this reduces weight by a few mg and also give a nice finish.
Wing posts go right through the motor stick and are sanded flush on the lower edge. I spend a while making sure these posts are aligned nicely vertically and horizontally.
That's where I am now.

Pics of the tapered end.

Mass table attached for the current position...


Si

[Skymon]

I finished off my motor tube over the weekend.
I missed my target weight by 16mg but I was happy with the end result.
It's a lot neater than my previous one.
I wonder if my wing posts are too long at 70mm.
Next time I fly I will move the wing down and see what it does

I put the plane together for a quick weigh on the scales and I am on 500mg exactly.
That's 12mg more than I measured in bits.
I am not 100% sure my scales are that accurate.
I struggled to get constant results from the very light parts.
These scales are your average cheap Chinese things costing under £20.

Pics of the end before the cap went on, showing my extra side brace.
I still have to grind the bearing front face flat and polish - who knows this might lose me a mg!

the journey continues

Si