build DB Mighty Barnstormer

[Nick Cripps]

3 hours ago, John Rickett 102 said:

If you change the incidence the model will adopt a different 'sit' in the air to achieve the correct angle of attack for the flying speed - decrease incidence and the model will sit tail down.

With the wing being quite a bit higher than the thrust line on this design there is a strong drag/thrust couple ie, an up pitch tendency due to the drag of the wing. 

Mr Boddington knew what he was doing!

 

There's your answer, Steve, and much more eloquently than I would have said it.

[kc]

It's so much easier to build exactly to the plan including incidence.

 

Looking at the Sea Stormer it would appear that 'Boddo' missed a trick by not making a Barnstormer 63 low wing version with wheels.  ( or have I missed seeing it? )  

[kc]

Back to the Mighty Barnstormer -   I wonder if its easier to have wing bolts projecting down from the wing so they locate into the struts and then put nuts on to fasten.  Means Loctite or locknuts etc to retain the wing bolts so they don't loosen.    I think it's easier to put nuts onto a bolt than try to insert bolts up into a blind hole - less chance of crossthreading.

[Tom Gaskin 1]

On my Boddo Twin Tub the parasol wing has threaded rods embedded in the wing that pass through the cabane, with nuts & washers to secure it. It does mean that the model has to be inverted to assemble it, but using my SLEC model table it is no bother.

 

Tom

[EarlyBird]

2 hours ago, Nick Cripps said:

 

There's your answer, Steve, and much more eloquently than I would have said it.

I experimented with the Mini Super and found exactly as John said.

Downthrust may need changing dependent on the pitch, when the model is first flown.

Incidence will be fine, as the plan. 

 

We have two SLEC model tables at the field.

 

Steve

 

[EarlyBird]

On 25/01/2024 at 05:28, Christopher Wolfe said:

Steve, you might consider shortening the nose a little.

For the spinner to be in the same position as the plan the engine mounting former needs moving back 30 mm, but I could easily make it 50 mm, more to think about.

 

Steve

[EarlyBird]

The fuselage cut parts came today, Sunday, and I couldn't resist checking them out. Which led me to the tailplane as the ribs are included. Then as I have been advised I could start on the tailplane as it's an easy way to get back into building. The building board is empty and not needed by Peggy Sue II.

 

What to do?

 

Steve

[EarlyBird]

Well, that bit of plan fits on the board.

 

 

Just! and that's only the tailplane. What have I started?

🤣

 

Steve

[Nick Cripps]

Same huge tailplane on the Sea Stormer, bigger than the wingspan of some of my models!

[kc]

Boddington tailplanes are often a peculiar construction- worth studying the plan well first.    Often they are built from flat ribs and then sanded to shape after installation.  Were the tailpalne ribs shaped already?

Edited February 4, 2024 by kc

[EarlyBird]

12 hours ago, kc said:

Boddington tailplanes are often a peculiar construction- worth studying the plan well first.    Often they are built from flat ribs and then sanded to shape after installation.  Were the tailpalne ribs shaped already?

Yes, they are. On the Mini Super they were as you describe, balsa strips added to the frame and sanded to a shape. 

[EarlyBird]

15 hours ago, Nick Cripps said:

Same huge tailplane on the Sea Stormer, bigger than the wingspan of some of my models!

🤔

Same here. It looks like flat bottomed wing, but it's not built one. This has started me thinking, and not sleeping.🤣

 

[kc]

Looking at the drawing on Outerzone  - the sectional drawing top left - it's not clear to me what the line across the tailrib is.  Maybe it's the inset centre section sheeting.   Hope you understand it!

[EarlyBird]

52 minutes ago, kc said:

Looking at the drawing on Outerzone  - the sectional drawing top left - it's not clear to me what the line across the tailrib is.  Maybe it's the inset centre section sheeting.   Hope you understand it!

Thanks kc.

 

The line is the bottom of the 3/16" centre rib and top of the 3/16" bottom sheet.

 

 

[Nick Cripps]

That's how I see it too, Steve.

 

Odd that it has a lifting section tailplane, they are normally only seen on free-flight models. I guess Boddo's intention was that it would be flown that way, with just the occasional intervention by the pilot.

 

Make sure you check the controls before flying, unlike Boddo...

[David Davis]

11 minutes ago, Nick Cripps said:

That's how I see it too, Steve.

 

Odd that it has a lifting section tailplane, they are normally only seen on free-flight models. I guess Boddo's intention was that it would be flown that way, with just the occasional intervention by the pilot.

 

Make sure you check the controls before flying, unlike Boddo...

 

Both the Radfio Queen and the Telemaster have lifting section tailplanes.

[Nick Cripps]

16 minutes ago, David Davis said:

Both the Radio Queen and the Telemaster have lifting section tailplanes.

 

True, but they are both older designs which were heavily influenced by the free-flight models of the time.

 

Maybe it was a bit of a sweeping statement but you'll rarely see a lifting tailplane on a modern RC design, unless they are trying to replicate that style of model.

 

Sorry for the distraction, Steve, back to the Mighty Barnstormer.

Edited February 5, 2024 by Nick Cripps

[EarlyBird]

14 minutes ago, Nick Cripps said:

Sorry for the distraction, Steve, back to the Mighty Barnstormer.

Not at all Nick. I have been wondering if the lifting tailplane and 3.8-degree wing incidence are connected in some way. As David pointed out.

25 minutes ago, David Davis said:

Both the Radfio Queen and the Telemaster have lifting section tailplanes.

Afterall this is also designed as a large easy to fly trainer which probably means it's easy to land.

[kc]

If that's just the centre rib then other ribs would be full depth I suppose.   But it could be that the laser cutting designer is as confused as me so maybe he interpreted it in a different way.     It's only sheeted in the middle isn't it?    If you have worked out the construction that's fine  - I just thought I would mention it at an early stage as I encountered a confusing  tailplane design on a smaller Barnstormer. 

 

Boddingtons lifting tailplane and his airfoil section all seem to originate from Vic Smeed designs  such as Electra.    The smaller Barnstormers had the same wing section as the Tyro Major and it appears to be similar on the Mighty Barnstormer.   

 

Frankly lifting tailplanes are a real pain if they are fitted under the fuselage like the Electra - just a slight error in positioning changes the way the thing flys.     On top they sit on a flat surface and are no problem.

 

 

Edited February 5, 2024 by kc

[EarlyBird]

It's easier for me with the cut parts.

 

 

It is as you supposed.

[kc]

It seems to me that the spar slots should align and  the TE should  coincide ( LE varies and has a triangle block too ).     A dry assembly seems needed before gluing just in case........

[EarlyBird]

That is spot on kc. 

[EarlyBird]

A start has been made this morning.

 

Dry fit while I work out what goes where and make some more bits.

 

Steve

[EarlyBird]

The glue has been put to good use.

 

 

Just the tips.to go.

They took some making, as I only have hand tools. 

 

 

[kc]

I notice that the plan you have differs from the one on Outerzone - your plan seems to have sheeting to the LE of the tailplane while this does not seem to be the construction shown on the Outerzone one.  Do the tailplane ribs have provision for this?    It does not seem to be fully sheeted so one would expect the ribs to have insets for the LE sheet.