Topic: DFW T-28 Floh - Scratch Build from a 3-view

After my sessions in the garage and on the Makin Plans thread over the last two weeks the plans are nearly done for my third scale Dawn Patrol mount for 2011.

You may have noticed my lack of commitment over the last year on builds and flying and fly-ins but at least i have a damn nicely decorated house throughout to show for it.

So I am not saying I am going to finish this, but it will be started...

The DFW T-28 or Floh was an attempt at building a slippery and streamlined fighter to outrun the fighters of it's day. This is 1915 and in my eyes this would have been very futuristic.

Fully enclosed engine.
Fully enclosed cabanes
Fully enclosed ailerons
And only the push pulls on the tailplane, no other supports.
Smaller wingspan to reduce drag

With it's 100bhp 6cylinder Mercedees engine it topped over 112mph on it's maiden fight, this was when it's equivalent English counterpart (DH2) was doing  93 mph!

It did have shortcomings though. On it's maiden flight the short wings required the speed to be kept up on landing, and the seating position meant the ground could just not be seen! It crashed on it's maiden. when trying to land. However it was developed and entered a number of selection trails but rejected for the visibility and high landing speed issues.

It was the first ever Walfisch, or Whale, fuselage which had the upper wing on top of the fuselage below the pilot...


Cheeky litlle fella ain't he? 

The Floh will be the smallest Dawn Patrol aircraft flying in 2011, at 85" span it is some 24" smaller than my Sopwith Pup...

I suspect it may fly a little like the Pitts Special rather than like a floaty Stringbag!

I will have the plans on display at Gaydon on the 24th October should anyone wish to have a gander (Laugh)

Here is a picture of it being handled to the strip prior to the fateful maiden....

And my favourite shot.

The only way the pilot could see to taxi was to stand up, what a scale feature that will be... 

And of course that classic grill/face... 

Anyone who has seen me flying my old lazy bee will know why I want to build this sooooooo much...

And well worth posting here ... A video from a flight sim version...

Think I need to build two now!


<a href="http://www.youtube.com/watch?v=EhpGSyuhDz4" target="_blank">http://www.youtube.com/watch?v=EhpGSyuhDz4</a>

And well worth posting here ... A video from a flight sim version...

Think I need to build two now!


<a href="http://www.youtube.com/watch?v=EhpGSyuhDz4" target="_blank">http://www.youtube.com/watch?v=EhpGSyuhDz4</a>

Can anyone identify that background music please, I want that for the maiden as an accompaniment

I can get you am MP3 of that background but obviously it will also have the engine sound there to if that's any help.

I can get you am MP3 of that background but obviously it will also have the engine sound there to if that's any help.

cool that would be great thanks Shaun. Watch this space and we'll see if a) anyone can identify that track and b) I actually get to finish start the little booga!

Hands off everyone, the Floh is mine...

Beep beep

sounds like Austrian omm pa pa 
did try looking properly but came up empty

Thats a great pic. In the background is a rare beastie indeed, a Lloyd C.V I think, with the semi monocoque veneered wings that have an incredible plan shape. The Floh aint bad either

Ian.

Thats a great pic. In the background is a rare beastie indeed, a Lloyd C.V I think, with the semi monocoque veneered wings that have an incredible plan shape. The Floh aint bad either

Ian.

Wow, Ian, you did well there.

That would be a great next build...

I'm looking forward to seeing this built. Looking at some of the German designs you have to wander what they were consuming in their leisure time.

Sorry Stu but it reminds me of the Thelwell ponies

Subscribed 

Richard

OOh me too 

Stuey have you got Mini Datafile 18 from Windsock.  More details in there.

MJ

Of course he has 

Steve

Of course he has 

Steve

From where then?

From THE Morris Aviation Library no doubt?

Too kind thou is

From where then?

From THE Morris Aviation Library no doubt?

Too kind thou is

Might have 

I am sure I am missing out on some information here  

No matter . . . .  

MJ

I am sure I am missing out on some information here  

No matter . . . .  

MJ

Thanks Mr J.... That info on the Lloyd is stunning, I love it.... It would be great to reproduce the above photo with both the Floh and The Lloyd in 1/3rd scale... One day. I'll add the Lloyd to my "must build someday" pile, in facts it's sitting there in number two position after the Floh.... And it has nudged the Starstrutter into third place!

And thanks to Idigbo for pointing that out otherwise I might have missed that..

You are most welcome 

just measured up the fuselage sides in 1/64th ply.....

Need to rethink as I would need two sheets of 24" by 48" at £50 each... £100 OUCH

Stuey have you got Mini Datafile 18 from Windsock.  More details in there.

MJ

Since our discussions Steve/Nigel, I have managed to buy one through e-bay, arrived this morning...

[ebay]130444671965[/ebay]

just measured up the fuselage sides in 1/64th ply.....

Need to rethink as I would need two sheets of 24" by 48" at £50 each... £100 OUCH

or £6 in 1/8th balsa...... mmmmm decisions...

Balsa with liberal amounts of well thinned dope then something like Sadolin or stain varnish to get a grain affect then a coat of something hard............ spray on glass Resin?

Or................... throw money at it and get the ply 

Balsa with liberal amounts of well thinned dope then something like Sadolin or stain varnish to get a grain affect then a coat of something hard............ spray on glass Resin?

Or................... throw money at it and get the ply  

Don't wanna throw money at this one as already have most of the expensive bits obtained cheaply already. AND IT MAY CRASH TOO!

The final finish is matt paint so I guess 1/8th balsa will do with some sealant, possibly even glass cloth

The final finish is matt paint so I guess 1/8th balsa will do with some sealant, possibly even glass cloth

What you worrying about then    Balsa it is 

May be worth trying some Diatex and dope as a tough'ish finish    Did you feel how hard the surface was on my Rafalroo at Osbourneby that's done that way and weighs no more than the tissue and dope I had been using and mine comes out at the same weight as others have built using iron on gloss film.  ~Obviously it's not as tough as glass but a compromise?

Thats a great pic. In the background is a rare beastie indeed, a Lloyd C.V I think, with the semi monocoque veneered wings that have an incredible plan shape. The Floh aint bad either

Ian.

   zzzzzzzzzzzzzzzzzzzzzzzzziiiiiiiiiiippppppppppp!!!!   wots that noise!!

  chris

stuey

  if you can do the sides in .8mm ply i can get it in a 5ft x 5ft sheet for less than half that 

  chris

Thats a great pic. In the background is a rare beastie indeed, a Lloyd C.V I think, with the semi monocoque veneered wings that have an incredible plan shape. The Floh aint bad either

Ian.

Just had another look at the photo.... And the tail is not serrated/scalloped as with the Lloyd... and also there appears to be three sets of struts on each wing.....

perhaps it's a DFW B1?

stuey

  if you can do the sides in .8mm ply i can get it in a 5ft x 5ft sheet for less than half that 

  chris

Ooooh, will have a measure up.... think 1/32nd maybe an overkill though. 

To bring this thread together I have copied a lot of posts from the detailing plans develolpment from the “Makin Plans” thread started by Charlie C. Now it’s all in one place and easier for me to refer back too and easy to copy and paste for out club magazine newsletter…

THE RIB

As this drawing plans thing is new to me then first thing was to scale up a small part first, something like a wing rib. The rib holds the DNA for the whole wing structure and also drives the position of fuselage formers. The very small 3 view I zoomed into as about as big as I could go without the lines becoming too thick... This came out around 5 inches long when printed out and included some of the full size scale details too. 5 inches is around 1/10th of the full size and for Dawn Patrol I need to build at 1/3rd scale.  Some calculation-ings are to be done....



Over that printout I added some equally spaced verticals along the bottom (x axis) so that I could than measure the heights to provide co-ordinates for scaling up...



...and then because I would need to multiply out lots figures to scale up I got the “old” MS Excel program powered up and entered my measurements and applied the 1/10th to 1/3rd scale multiplier required... so now I have the target co-ordinates at my required scale of one third....



Collected some tools to draw up the size of rib required as in the attached..




Then started to draw a straight line across the bottom (x axis), and then verticals up along which I will measure the Y co-ordinates... I used the compasses to scribe the distance up from the x axis and lastly joined the dots to give a rib about 17" chord. I tried the flexi curve but it came up too lumpy... Better off freehand... Also added the break line for the ailerons too as this will be needed to add the rear spar positions and false trailing edges..



Having got the outline of the Rib, some 423mm long and around 62mm tall I need to consider the wing structure next.

WING

This will be a functionally single bay rigged biplane spanning 85". Each wing will have brass tubes to match similar brass tubes mounted in the fuselage. Piano wire will then act as joiners/incidence pegs. I am thinking of 1/8th balsa ribs though-out, bar the root and second ribs (1/8th ply to support the dowels) and the ribs each side of the inter-plane struts (1/8th Liteply). The root rib will be two parts as suggested by Idigbo, the outer will not have the cutouts for the spars to increase the strength of that assembly.

Each wing will have four spars, two each vertically stacked for front and rear structures that are webbed together. These to be made from 6mm square spruce held 40mm apart by 1/16th balsa spar/shear webs with grain running vertically. The trailing edge is quite thick and not scalloped so this will be balsa t/e stock. Leading edge just a strip of 10mm balsa but it is sheeted in past the forward spar assembly...

Top and bottom wings are nearly identical except the top wing has a span longer than the lower wing. This is achieved by using a wider spacing between the root rib R1 and the next one along R2 on the upper wings than I will use on the lower wings. It is a single bay rigging structure so the inter-plane struts will exit differently. Other than that they are identical. The ailerons are massive considering it was built and flown in 1915.... and there are four of the things.  We are expecting Pitts Special performance here…

The ribs' spacing has been scaled up from the three view. So a rectangle was drawn (lightly) of the overall wing size and the rib spacing added. On the full size the four ribs nearer the root were wider apart than those four outboard. I guess this is to support the ailerons on the outboard and allow spacing for the wing mounted tanks and radiators.



difficult photo here as the 2H pencil is quite hard and draws a fine line...

and this grid was used to plot the lovely curves on the outboard leading edge and inboard/outboard of the trailing edge.  Also added the aileron and thickened up the ribs to 1/8th



False 1/4" by 2"(high)  trailing edge and aileron leading edge added too...



Next job will be to add the rib capping, the leading edge sheeting (with scallops) and trailing edge.... Then add the spar detail.

well that worked well then, I have a wing plan, complete with a servo and sheeting etc...

here are some views...







and the good thing is that one drawing will build me all four wings. Although the lower wings are an inch shorter in the span department, I will just move the root rib that distance and “square off” the trailing edge where it meets the lower fuselage...

TAIL

Bouyed up with the result above I started the tail feathers...

In this picture I have matrixed the small three view to work out my plot points, these are scaled up and transposed to the final third scale view.



Strange to think the original designer was plotting the same curve 95 years ago..


The stabiliser is too wide to draw on one piece of wallpaper so i am drawing half of it first. Positioning the centre line along the edge... Then I can trace that and replicate it onto another piece and offer that up to the first.



Also have one elevator half too..... the control horn is there with the closed loop push pull running through the stabiliser exiting below and then into the fuselage.... At Phil Clatk's suggestion I will skew the horn to be in line with the pull cables..



one thing left to work out are the strap and rod hinges, how am i going to do it, ie, where does the rod fit 

And the Rudder drawn at scale size, for the first flights I will do a rough and larger version as the original looks a little small.

Just to recap for my own future benefit before I start on the Fuselage.

1   use 6 by 6 wing spars
2   add spar webs from root rib to the strut bay
3   laminate the root rib to include a blank adjacent to the fuselage
4   change the incidence dowel pegs for brass tube and piano wire
5   rotate the control horns to be in line with the pull pull cables
6   change the leading edge of the elevators for 1/2" dowel or carbon tube to enable straptype hinges as seen on the Fokkers.....

THE FUSELAGE

After consulting with Mudflapporious and Idiggers I could build it in two halves split vertically or horizontally. It's around 50" long and 24" high and shaped like a whale... It's all curves but most are simple curves, the only compound curves are forward of the firewall... and the tops and bottoms....

The sides are flat (vertically) tapering in towards the front and back.

That's all the stuff copied over from the "Makin Plans" thread so everythimng from here on in will be new...


Next job is to draft out the outline and former, wing, engine, tail and undercarriage mountings so I can position the formers. I will have 8 of them connected with four full length spruce longerons and additional balsa stringers to support the planking. Favourite at the moment is 1/8th balsa and then glassed due to the cost of ply.......

This will also help with the fuselage shape.... And I love to watch it...

<a href="http://www.youtube.com/watch?v=EhpGSyuhDz4" target="_blank">http://www.youtube.com/watch?v=EhpGSyuhDz4</a>

Wow. that is a DIFFERENT shape in the sky!  I look forwad to seeing this one develop Stu. 

On the vid, it does make you think that there is a tiny fin rudder area compared to a massive fuse side area.  On the real thing, I pity the poor pilot is the wheels caught in a rut, it does look as though it would roll over quite easily.. and what the heck was in the bottom half of the fus??  strange idea but I hope that model is a great success.

more  power to your elbow mate 
stu k

right, all the design decisions made in my head and most committed to paper. Some I need to see the thing take shape to develop as it comes together...

Have my materials list now so it's off to SLEC tomorrow on thay back from a meeting in Cambridge....