Prototypes G.B. General Discussion

Weaver · June 29, 2020, 09:12:52 AM

Splendid - thanks gents.

I'm just debating how to get the rotors far enough off the ground. One way would be to give the wings a lot of dihedral like the XR-1, but that's difficult because the NOVO Hotspur's wings fit in aerofoil-shaped recesses in the body. The other is a combination of short pylons on top of the tip pods and long undercarriage.

Mossie · June 29, 2020, 03:33:27 PM

How about a short horizontal inner wing to house the undercarriage?

jcf · June 29, 2020, 04:30:05 PM

You'll want to go to a taller undercarriage route because of ground-resonance issues.

The stub-wing carrying the gear is a good idea and GAL used that layout on the Fleet Shadower.

Or you could go fancy and have a stub-wing with retracts like the Heston Phoenix or
Krieder-Reisner XC-31.

Weaver · June 29, 2020, 04:30:25 PM

Quote from: Mossie on June 29, 2020, 03:33:27 PM
How about a short horizontal inner wing to house the undercarriage?

That'd work geometrically, but it puts an extra joint in the drive shafts, in a craft that's already going to be struggling with weight issues.

Weaver · June 29, 2020, 04:41:05 PM

Quote from: joncarrfarrelly on June 29, 2020, 04:30:05 PM
You'll want to go to a taller undercarriage route because of ground-resonance issues.

The stub-wing carrying the gear is a good idea and GAL used that layout on the Fleet Shadower.

<pics>

Or you could go fancy and have a stub-wing with retracts like the Heston Phoenix or
Krieder-Reisner XC-31.

<pic>

Both of which would be good ideas if the base craft was a Hamilcar, BUT I mis-typed in my original post (see edit): the donor is a Hotspur, not a Hamilcar, so it has a mid-mounted wing, which makes stub wings a bit too close to it. There isn't any problem fitting longer fixed gear to the existing wing-root mountings; I just have to find/make the legs. However it would probably be safer to mount it further outboard since the weight of the rotors at the wingtips makes the vehicle much more likely to tip sideways.

I agree that ground resonance would be a problem, but since this is a very early helicopter, and since ground resonance was pretty much discovered the hard way, I'm inclined to bake some into the design in order to set it up to fail in the back story.

Hotspur: https://en.wikipedia.org/wiki/General_Aircraft_Hotspur

Weaver · June 29, 2020, 10:03:00 PM

Turns out that with a bit of lateral thinking, there IS a way to angle the wings upwards without too much work, and it has the bonus of angling the u/c legs outwards as well, so I'm going with that.

PR19_Kit · June 30, 2020, 02:06:40 AM

It's called dihedral..................

Weaver · June 30, 2020, 03:06:07 AM

Quote from: PR19_Kit on June 30, 2020, 02:06:40 AM
It's called dihedral..................

Well yes, but I'm not doing it for "dihedral effect" (i.e. roll stability), i'm doing it to raise the rotors off the ground.

McColm · July 04, 2020, 10:31:57 AM

Another subject for me would be the Fairchild C123L Provider, this is the proposed T-64 turboprop engined variant. Although further research indicates that a four engined turboprop was also considered but never got past the drawing board..
Then there's the Chase XC-123A fitted with four turbojets, I'm leaning towards a pair of turbofans probably from a Lockheed S-3A Viking.

AeroplaneDriver · July 11, 2020, 08:14:07 PM

Apologies if this has been asked l, if it did I missed it, but anyone know when they started using the black and white photo calibration markings on prototypes?

PR19_Kit · July 12, 2020, 03:51:44 AM

Do you mean these things?

At a guess I'd say in the mid 70s, I can't recall seeing any before that time period anyway.

AeroplaneDriver · July 12, 2020, 04:21:09 AM

Yes Kit, those things. I was thinking 60s/70s. I just can't find a real answer on when they were first used.

PR19_Kit · July 12, 2020, 04:30:30 AM

I've tried searching too, but can't find anything definative.

kitbasher · July 12, 2020, 04:31:38 AM

IIRC I've seen at least one pic of a P-39 with the B&W quarter markings as per the bottom two lines. I think it may have even been an RAF one being used for RN catapult (?) trials.

EDIT: OK deck landing trials. See
https://www.72news.eu/2017/04/rs-models-bell-airacobra-mki-reissue.html
https://www.hobbysta.eu/bell-airacobra-400-fighter-p-28242.html
http://rsmodels.cz/en/modely-letadel/plastikove-modely/1-72/92131/airacobra-i-p-400

pic of the real item at https://uamf.org.uk/viewtopic.php?t=4151

zenrat · July 12, 2020, 05:03:10 AM

I found this picture.

I think its a late sixties NSU.

This is a '59 Mercedes.

as is this which doesn't have the markings but looks like a fun accessory for your Merc.

Not sure what this is (although the tail-light treatment looks 70's - Kit will know) but it does have the circular symbol.

This is a Subaru 360 made from '58 to '71.

None of which answers the question with relation to aircraft.