Flights of Fancy

[sprogs]

Hi Pedaldog, (MY brother!)
I have the plans for a depron Walrus, like I told you, and you forgot. I'm posting it here so I can remind you that I told you about it.
Also, I am posting an "I told you so" just to rub it in.
Liz.
(Your sister, if you remember, I was here earlier, remember ?)

[sprogs]

......and while I'm here.
My dream is to make models of all te aircraft that have held the title of "World's smallest".
1/ Stits junior.
2/ Stits Skybaby.
3/ Starr Bumble bee.
4/ Starr Bumble bee ii.
5/ Stits baby bird.  (Bah, Humbug !)
I want to build them for rc at 1/3 scale or about.
I already have plans and/or parts for 1,2and 3, drawings from Bob Starr for 4, but the only thing I can find for 5 is a 3v from somewhere or other, listed as plans but not.
Peter Smart, (bow, scrape, I am not worthy etc....) the master artist of scale, built a peanut baby bird but I have not been able to contact him to see if he would pass on his plan.
Anyone know him ?

P.S. I don't think the baby bird really justifies the title as it only ever made flights up and down a straight runway. I know that Bumble bee ii acrashed, but that was on it's acceptance flight. It had already proved it's ability to do circuits. I still want to make it though.
Liz.

[Pedaldog.]

DOH!  I want a Walrus of, around, 30 - 36" span.  Stick and Tissue, not Depron.

[TheLurker]

5/ Stits baby bird....
Peter Smart, (bow, scrape, I am not worthy etc....) the master artist of scale, built a peanut baby bird but I have not been able to contact him to see if he would pass on his plan.
Anyone know him ?

Peter tends to build from what I can only describe as augmented 3 views.  Of the last two I had from him only the Willow Wren ( see upthread) was what most of us would regard as a fully worked up plan.  Cv19-ο permitting I'll be seeing him about 3 weeks from now and I'll quiz him then, but given that you are looking at a 1/3 scale RC version I'm not sure how much a Peanut scale plan would help. 

As for Peter's mastery?  Absolutely no disagreements here.   Not only do they look the business, they fly well into the bargain.

... baby bird really ... only ever made flights up and down a straight runway.

Having looked at the size of the rudder I'm not surprised.  I can imagine it being more than a little directionally wayward and, game as I am for experiments, it's one I wouldn't consider wasting wood, tissue and time on.

[TheLurker]

As seen 7.6g for round numbers.  The planned motor will be about 2g dry weight and as it's currently balancing a bit aft of the spar some nose weight is going to be needed.  How much?  Not a clue m'dear, but I'm hoping for less that 1g giving a take-off weight of up to about 10.5g.

Will it fly?  Dunno.  Main problem is that the interior of that fuselage is, "compact and bijou" so I may not be able to get the planned motor in.  However the target weight, balanced without motor, was 12g so wing loading is favourable.  Find out on the 18th.

[andytheflyer]

A work of art L.  I am amazed by your dealing in 0.5 of a g.  If mine came out within half an lb of target weight I was happy.

[TheLurker]

Lurker how do you work out how much aileron to get them circling without hitting the walls? It must be different for every model and presumably differs with the amount of power as well.

A great deal of,  "suck it and see" accompanied by a large helping of pained wincing as they hit the walls followed by anxious inspection to see if it'll still fly.   

And to demonstrate ...

https://vimeo.com/ 658157931  <= *sigh* yes it's the usual story, bolt 'em together.

Flying at 7.86g without motor and motor is 2 x 3/32" x 14" with a dry weight 1.8g. 
Didn't get the turns above 500 - 600 and it was in the rafters from ROG so am going to strip some thinner rubber, 70 thou. has been suggested.

Ran out of time today, so hoping to get the circuit sorted out and lose that last little bit of stall at the January meeting.

ETA.  Sorry Sprogs, no joy on the Stits Baby Bird.

[TheLurker]

...and after a few hours tweaking.  Going from a 0.09" section motor to 0.06" via 0.08" & 0.07", losing the nose weight & down-thrust and a tiny bit of of right thrust the Courtesan is more or less there.  The trim tabs can probably be reduced in area a bit and it looks like it could do with a leetle bit of the nose weight reinstating.  I might try it on a few more turns (currently 900-1000) to see if I can get it to RoG but that probably won't be until March.  However I'm content that the Courtesan can be marked as "complete" so I can start on the next one, whatever it might be.

Not just my machine in this clip - https://www.youtube.com/watch?v=lbT0f-bOYzw

Running order.
RC Flying Flea alike
Lurk setting up the Courtesan for (yet) another test flight
Some RC PTW nonsense
AB winding on turns for his No-Cal MK XIII DH Mosquito - which is proving a pain to trim
Me & the Courtesan
AB (inwardly) swearing at his Mossie
CB & his Bowden Baby Dragon. Initial trimming. A scaled down version for rubber of 1930s ICE design by Col. Bowden
JW & his Miles M12 Mohawk.  Initial trimming.  A one-off designed by Miles for Lindbergh when he visited the UK.
CB & the Dragon.  One the first near full power flights. Almost, but not quite trimmed out.
SH & a type I don't recognise.  This was flying nicely earlier.  Suspect the motor was "tired" by the time this RoG was attempted.
MS & a Bucker Jungmeister.

[TheLurker]

This is Martin Fardell's Avro 504N, 108" span.   Sit back and enjoy the flying and the skylarks...  https://www.youtube.com/watch?v=IfOaudP04zI

[andytheflyer]

That is extremely impressive Lurk. I fully appreciate the levels of skill needed to build and trim those models.  Well done.  Chapeau sir.

But I still don't know how you get a 9ch radio and the OS52 in there.......

That yellow bipe is only a gnat's gnadger away from a proper ROG.

[TheLurker]

That yellow bipe is only a gnat's gnadger away from a proper ROG.

It is, it was flying nicely earlier.  I think a fresh motor with a trim tab, or gurney strip, on the port wing - or perhaps a bit of stbd tip weight -  to counteract the torque roll would see it away.

[TheLurker]

Pedaldog, saw this today, https://www.hippocketaeronautics.com/hpa_forum/index.php?topic=26307.msg282241#msg282241 ,  & thought of you.

It is (will be) a scaled down version of this - https://outerzone.co.uk/plan_details.asp?ID=9769


In other news, hoping to have this flyable, well trimmable, by mid March.

[Pedaldog.]

I like that one, thanks.

[pcolbeck]

Lurker why do most model planes use twin bladed props when most real aircraft since the 30s have used three or four bladed props ?

[TheLurker]

Lurker why do most model planes use twin bladed props when most real aircraft since the 30s have used three or four bladed props ?

Good question, well asked.  Not a b****y clue.

I *suspect* it's because 3 & 4 bladed props are comparatively more difficult to make and balance than 2 blade props and once the model's aloft it doesn't much matter.  You also need (at least for rubber powered models) a larger than scale fairly coarse pitch airscrew so any scale "look" for a 3, 4 blade prop is instantly lost which makes it a bit pointless to make one.  However, that's speculation so don't rely on that lot in court, eh? 

Some of the keener scale modellers flying CO2, electric or IC power do make 3 & 4 blade props that are much closer to scale in both pitch and diameter.

[TheLurker]

Test flying the BE2c today.  Not a success.  Back to the drawing board I think.  New wings with more dihedral as the first measure.  The joys of prototyping a design.

However, Peter Smart was flying his rubber powered Gossamer Albatross and I made sure I got some footage of that cos a rubber powered version of a pedal powered aircraft is just too good to miss.  Well, I think so.

Gossamer Albatross   https://vimeo.com/ 690017318  <== bolt them together.  Go on. It's worth it.

If you use Opera as your web browser it's unlikely that the newsreel will play.  Try Firefox, Chrome or even Brave if you've got them installed.

[TheLurker]

Lurker why do most model planes use twin bladed props when most real aircraft since the 30s have used three or four bladed props ?

Here we go, someone doing it "properly" ....

https://www.hippocketaeronautics.com/hpa_forum/index.php?topic=26525.msg283663#msg283663

And some additional footage from the last indoor meeting - https://www.youtube.com/watch?v=DOE_6U_Yqfk

The Camel & the Bantam are both CO2 powered.  When this was filmed the Camel was still being trimmed.

[philip]

Lurker why do most model planes use twin bladed props when most real aircraft since the 30s have used three or four bladed props ?

Two blades tend to be more efficient, because each blade is passing through air that is less disturbed by the blade ahead. A single blade is theoretically the most efficent but balance and weight make them less practical.

Full size aircraft have an additional concern, the blade (or most of the blade) must remain subsonic. A low powered aircraft can use a two blade propellor, but if the engine power is increased the propellor might spin too fast and reach the subsonic limit. The more powerful aircraft must make the propellor 'harder' to turn so that it can 'absorb' the power without spinning too fast, one can either make the propellor larger in diameter (but this is generally limited by ground clearance) or one can add more blades. The Spitfire prototype had two blades, early production had three blades, the more powerful later models had four or five blades.

[philip]

The other thing a full size aircraft can do is add more propellors. I suppose one engine could drive multiple props, but the usual solution is more power via multiple engines each driving one propellor.

[philip]

I've just remembered that some of the very powerful propellor planes did have engines that drove two contra-rotating propellors.

[Mr Larrington]

The still-in-service Tu-95 BEAR has contra-rotating props, the tips of which do go supersonic.  As a result it is one of the noisiest things ever, albeit allegedly not a patch on the Republic XF-84H Thunderscreech.

[TheLurker]

... A single blade is theoretically the most efficent but balance and weight make them less practical.

You may be interested to know (if you didn't already) that a lot of rubber powered duration models (e.g. Wakefield & similar classes) use single blade props.  They're often folding as well to reduce drag in the glide phase of the flight.

[TimC]

Prop theory is incredibly complex - ask a helicopter pilot! The aeroplane I flew for many years, the C-130 Hercules, was initially produced with 15.5ft 3-bladed props which worked very well at high cruising speeds (the early Herks cruised at around 340kts TAS), but were crap at slow speed where you really needed to get the power working for you to get into and out of short, unprepared strips. From the C-130E (and retrofitted to earlier C-130s), the aircraft had a 13'8" four-bladed, 'paddle blade' prop that halved the take-off run. It lost 10-15kts at cruise speed, but could lift another 20,000lb (an extra 400shp per engine from the C-130K helped too!). The supersonic tip thing is managed by making the prop constant-speed, which was a technology developed before WW2. The Herk's engine/prop combination was totally constant speed, with the engine always turning at 13,800 rpm and the prop at 1021 rpm.

[Mr Larrington]

Seems the latest C-130J has those new-fangled scimitar props with six blades apiece.  No good will come of this kind of meddling with the Dark Arts.  It bain’t be natural.

[TimC]

It gets worse, the latest C-130T (the J is now 25 years old), which is an upgraded H-model, has 8-bladed props. They're multiplying!