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Flea Fli Build Blog

The electric version

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Martyn K06/10/2013 22:51:45
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5102 forum posts
3701 photos

Flea Fli

Flea Fli

Just in case the Flea Fli gets selected for the 2014 mass build (sadly not looking very likely unless a lot of tactical voting goes on), I thought that I had better actually make an electric version.

So in the lull between building the Magic, flying, essential maintenance and actually earning a living, I have made a start on no.1 of possibly 2 Flea Flies.

Unusually for me, I have made a start on the wing. Potentially, this could be built by a beginner so there may be a few more 'obvious' construction notes.

 

The Wing

Create a 1/16" ply template from the section shown on the plan. The master template is used for all the ribs, the specials are modified from this

pa030001.jpg.

Use 1/16" quarter grain wood for the ribs (if you can get it). It is much stiffer than straight grained wood. It has this characteristic speckled 'Mackerel Sky' appearance.

pa030002.jpg

Note the template only has slots for the spars cut. The full slot is removed when the rib is ready to be inserted. Use a good scalpel and a new blade, it makes life much easier.

pa030003.jpg

I thought that I had better check that there is space for a LiPo. This is a 3S 2200 but there is sufficient space for a 4S if required. Access will be via an upper hatch so the model can be kept assembled. I have selected a rear mounted 2837/18 (about 1100kV) brushless motor from Giant Shark - this should drive a 9x5 prop and give comparable performance to the original if I keep the weight down. Target weight will be 2.25lbs ready to fly.

pa060011.jpg

Making a real start on the wing, you need to make 3 of these little jigs to support the LE at the correct height. Make 1 accurately and then pin it to another piece of balsa and cut round it using a razor saw. Seemples.

pa060012.jpg

The lower spar is pinned down and 3 ribs (each end and middle) are located but not glued. Put the LE onto the jigs and push back into the ribs so that there is a nice firm fit. Check that the ribs are all the same way up. The chances are that the upper and lower spars may not quite line up as accurately as you would imagine. Leave the spars slightly too long at this time, you can cut them back later.

When pinned down, start glueing the ribs in - don't worry about the ailerons at this stage, the excess ribs will be cut off later. Check that each rib is vertical using a square

Note that the first rib in from the root is specified as 1/16" ply. I have used 3/32" lite-ply. I will use seperate aileron servos - I'll worry about how they are fitted later.

More to come

Martyn

Edited By Martyn K on 06/10/2013 23:06:14

Biggles' Elder Brother - Moderator06/10/2013 23:40:57
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15748 forum posts
1460 photos

Very nice Martyn - watching with interest.

BEB

Steve Dunning07/10/2013 09:47:29
324 forum posts
186 photos

An excellent choice Martyn. The fact that you look like using a 3S, 2200 lipo puts it in the popular size/very affordable model category. Great for putting in the car in one piece, especially in cold weather. Following with interest.

Steve

Martyn K07/10/2013 11:54:30
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5102 forum posts
3701 photos

Hi Steve

I don't do much electric, but what I do, I have standardised on this power setup. This will be the 4th model with this battery size.

And yes - keeping it in one piece is the objective..flying 'incidents' excluded.

Martyn

Martyn K11/10/2013 21:24:10
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5102 forum posts
3701 photos

So far this week, I have made a bit more progress. Sadly my Olympus shack camera has died so I has to redo some photos using a phone camera - no flash so shadows are rather obvious and a couple of build shots have been lost.

Add the upper rear and upper front spars - leaving them slightly too long and repeat the build process for the opposite panel. There is a dotted outline on the plan - its quite easy to follow.

Note that the other front spar has not been added at this stage.

When both panels are dry, turn either panel upside down - actually right way up and pin the panel flat (on the plan) with pins through the spar. You should check it is flat by measuring the height of the TE centre line above the board. The height of the centre line on the LE should be the same. Use a couple of wedges to keep it stable.

Cut the LE and lower spars vertical over the centre line. I use a razor saw.

Cut the other panel spars to length, pin a 1.5" prop under the front spar at the tip and carefully sand, cut all three spars and LE to a good fit (on both panels). They will all need a slight taper .

002.jpg

Use a couple of pegs or clamps to hold it all stable while you check the joints and when happy, glue them up. Use a bit of polythene to stop the pegs sticking to the glue while it sets.

003.jpg

I used a PVA based adhesive - and lots of it smeared over the joint as well. It will be quite fragile at this stage.

001.jpg

The wing waiting for the glue to dry.

While you are waiting, cut out the ply dihedral braces. I use good old fashioned carbon paper, but I only mark the corners and the centre line and join the dots using a ruler and pen.

006.jpg

This is about the only use I have for a Stanley knife now - with a new blade. Don't try and cut through in one go - use a straight edge and a series of score lines and it will soon go through. Just be patient.

More to come

Martyn

kc12/10/2013 17:08:05
6722 forum posts
174 photos
Martyn didn't give details of the plan, but I assume he is building the standard size 39 inch plan. That is a 66percent version of Kwik Fli 3 by Phil Kraft. This plan is a MyHobbyStores plan number RC 897 and has been re-numbered recently. It was RC 987 when it was a MAP/ Nexus/ Argus plan before MyHobbyStore typed it as RC 897 in their listing.
It was also a Model Airplane News ( USA) plan from October 1968.
I think there was a larger.40 size version too.

Edited By kc on 12/10/2013 17:09:25

Martyn K12/10/2013 20:45:51
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5102 forum posts
3701 photos

Hi kc

I am building the 39" span model which was a free plan in 1968. Thanks for the clarification on numbers etc.

It's a nice easy build - just need to get on with it. I wasn't aware of a Phil Kraft produced 40 sized model, however, I would imagine that there have been a few derivatives over the years

Thanks

Martyn

Bob Cotsford12/10/2013 21:44:20
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8793 forum posts
494 photos

 

I have an airfame that I think is a 40 size Fli, at least the dimensions and layout match those given on the Trenton site. It came as a part completed airframe with a foam wing, and looks to be 80s from the state of the veneer and the 40 size mount fitted. Whatever, it is now referred to as KFC (Kwik Fli Clone) and with an ASP53 in it's snout it flies an absolute treat. The barn door ailerons create a lovely screech on full deflectioncool

kfc side view.jpg

 

kfc top view.jpg

Edited By Bob Cotsford on 12/10/2013 21:49:10

Martyn K01/11/2013 14:22:40
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5102 forum posts
3701 photos

Work on this has been progressing while waiting for resin to dry on the Magic build - so not really that much done..

Continuing with the wing..

The TE ribs where the ailerons will sit have been sliced away. Phil Kraft advises to cut the ailerons out after the wing has been built, I think this way is easier.

photo0016.jpg

Blurred photo (must be one of BEB's) showing the TE sheeting going on. The sheet is very light, the clamps need to be very lighlty loaded or you will end up with dings in the wood.

photo0017.jpg

The centre section showing the centre rib, lite ply outer ribs and dihederal braces. A bit more sanding is required on that rear brace,

photo0018.jpg

Cut the TE too wide - trim it back when the glue is dry. The lower sheeting is chamfered so that an extended line from the wing ribs passes through to a point, I think that is too much, mine is thinned to about 1/32" of an inch thick. Any thinner and you may end up with the TE warping.

photo0021.jpg

After the rear part of the ribs where the ailerons fit have been removed, add 1/16" sheet across the rear spars - grain lengthways. Sand it flush with the upper and lower spar.

photo0023.jpg

While waiting for the glue to dry, cut out the doublers (ply) that will support the outer U/C block. The original was only half a rib wide but 1/16" birch ply, I have elected to use a 3/32" lite ply doubler.

More to come.

Martyn

Martyn K01/11/2013 14:36:23
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5102 forum posts
3701 photos

A couple of extra photos and a bit more progress.

The upper TE sheeting is added when the lower sheeting has been cut to size and chamfered correctly.

photo0033.jpg

Work then starts on the ailerons. Phil Kraft hinged his using film - there are no aileron hinges shown on the plan. I am planning to use the kevlar cloth for all hinges on this model and the build will be modified to accommodate this (or use mylar hinges).

Because the hinge is on the top, the lower part of the aileron is narrower with a gap to allow it to deflect downwards. The correct gap is shown on the plan and an additional piece of 1/16" sheet is glued to this and angled forward so that it touches the upper rear spar.

Make it a tight fit between the last rib of the wing and the completed TE. The last rib will eventually be removed so that there will be a nice even 1/32" gap when the aileron is fitted. The aileron ribs are cut using the standard ply template and then trimmed to fit. Don't add the upper sheeting yet..

photo0034.jpg

A start can be made on adding the very light 1/16" sheet balsa LE "D" box sheeting. Leave a short gap (1/32" where it overlaps the width of the spar so that the cap strips have got something to glue to. Note that I am using pins to protect the delicate sheeting from clamp damage

More to come.

 

Martyn

Edited By Martyn K on 01/11/2013 14:37:22

Martyn K04/11/2013 11:29:44
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5102 forum posts
3701 photos

A bit more progress.

I have continued with the LE sheeting (3 out of 4 done) and added the Undercarriage mounting blocks.

These are quite simple to do in situ. From the plan, measure back from the main spar to the front of the block. I think it was 30mm from memory.

cut a slot using a razor saw with the u/c block as a guide (resting on the ribs) to make sure that the cut is at the right angle. Don't try and cut it in one go, take it in stages. Then move the block fractionally forward so that it is very slightly (the width of the saw blade) in front of the slots that you have just cut and cut the rear slot - again using the block as a guide. Don't cut too deep. Use a scalpel to remove the wood between the two slots. Keep easing the wood away (extending the slots) until the block sits nicely in the cut outs (across three ribs) but sitting 1/16" proud - so that it will sit flush with the sheeting - I used a bit of scrap sheet to get the depth right.

photo0043.jpg

Before you glue the blocks in, drill the holes for the undercarriage leg and cut a slot. These are quite easy to cut with a Stanley knife held at 45 degrees and against a straight edge using the hole as a width reference.

Glue it in and allow it to set.

You can see from the photo the nearside thicker lite-ply rib and the next but one rib out has the lite-ply doubler added.

More to come.

Martyn

Martyn K06/11/2013 13:23:08
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5102 forum posts
3701 photos

A bit more progress on the wing.

The lower centre section sheeting has been added. the gap between the LE sheet and the TE sheet is actually 3 pieces, one in front and one behind and a small piece to the inside of the u/c blocks

photo0062.jpg

The 1/2" very soft sheet wing tips have been added and the LE planed and sanded to shape.

photo0064.jpg

Note that the final carving of the tip wont be completed until the cap strips and ailerons have been fitted..

photo0065.jpg

The aileron mounting rails have been added. These are simply 3/8" x 1/8" spruce inlaid into the ribs and the front one butted and glued to the spar. The servo has been inserted from underneath to keep the profil low and airflow over the wing as smooth as possible.

photo0061.jpg

(A bit blurred - just too close for the phone camera...)

photo0063.jpg

Lower cap strips added and the servo boxed in with 1/16" sheet. Access (if required) will be from the upper side of the wing through a suitable orifice - created when needed.

More to come

Martyn

Colin Leighfield06/11/2013 13:30:31
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6007 forum posts
2505 photos

That's a proper model. Oh for more time to build them all.

Martyn K06/11/2013 13:48:05
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5102 forum posts
3701 photos

Thanks Colin

Surprisingly, there is not a lot of interest in it though. Still I am not worried, I am enjoying the build and I don't mind writing it up for posterity a couple of times per week.

It's actually quite handy having a small model on the go (so to speak), its cheap and I can spend 30 minutes here and there and make some real progress - working on the Magic is much more time consuming and needs much more thought and space. (Due to its size and complexity).

This is a perfect foil for the Magic.

Best wishes

Martyn

David Rothwell06/11/2013 14:26:10
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147 forum posts
3 photos

well I`m Watching and buildingthumbs up

Martyn K06/11/2013 14:29:57
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5102 forum posts
3701 photos

Thanks - that's great and reassuring.. When I get round to hinges, if you want some of the Kevlar hinge material that I use, let me know and send me an SAE and I'll get it straight back to you. (Ditto - any other Flea Fli builders out there).

Martyn

Steve Dunning06/11/2013 15:07:04
324 forum posts
186 photos

You might have got me motivated with that Martyn. Thought about it for a while and the 2200/3S battery brings it into the cheap to run area and great for putting it in the car in one piece. Keep going mate!

Martyn K06/11/2013 15:14:12
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5102 forum posts
3701 photos

Thanks Steve

Will do - remember I have to build an IC version afterwards. Got a couple of period engines that will fit nicely..

Martyn

Colin Leighfield06/11/2013 16:56:36
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6007 forum posts
2505 photos

Martyn, over the last couple of years I've expanded my collection of small i/c motors with the view of re-creating some of these classic models. I've got a Cox .049 with r/c throttle to go into the Jr. Sklark referred to recently. Also a few months ago I managed to build a Doug McHard Wee Snifter, fitted with r/c on rudder and elevator, with a Mills .75. I'd forgotten though that Solarfilm and diesel fuel don't go together (!) so need to re-cover that before I try to fly it. I've also picked up a promising new Norvel .06 which looks very useful.

While I'm well into electric, I want to use some of these engines (2 Mills 1.3s, one of them a new Irvine example) and these smaller models don't break the bank, do they?

I have determined though to stop flitting from one project to another and actually finish things in sequence, this is taking time but I hope to make progress and get some flying in as well! Nil desperandum, but I'll get there.

The Flea-Fli is a real classic, you definitely need to do one with an I/C motor though.

kc06/11/2013 18:42:30
6722 forum posts
174 photos
I am also watching the build, it's just that you covered every point so there is no need for us to add any comments!
It is just a little on the small side so if it's also quick and a bit twitchy I might build one a bit bigger, say 125 percent. A dimensioned Kwik Fli drawing is somewhere there on the Trenton site and this would make a percentage change of size a piece of cake...mostly straight lines too.
OK one comment I can make is I was surprised that the u/c mounting blocks didnt meet in the middle to reinforce the wing and so that the u/c upright blocks can reinforce each other.

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