HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Sep 08, 2002, 09:01 AM
MAAC 6251
Ottawa, Ontario, Canada
Joined Jan 2002
699 Posts
Discussion
Handley Page Halifax has up thrust?

I'm just in the early part of scratch building the Handley Page Halifax four engine bomber. What concerns me is that the aircraft seems to have a lot of up thrust in the engine set up.
Anyone have any experience with up thrust on a big bomber?
Rob.
RobZ is offline Find More Posts by RobZ
Reply With Quote
Sign up now
to remove ads between posts
Old Sep 08, 2002, 10:44 AM
Registered Lifeform
Paul Willenborg's Avatar
Little Rock,AR,USA
Joined Jun 1999
801 Posts
Yes, it does. No I wouldn't!

Hi Max,

I just checked two different Halifax drawings and you are quite right- it does have significant upthrust!

One drawing actually has datum lines and says that there was slightly over three degrees upthrust. Another drawing of the radial engine variants also shows upthrust, but does not specify the amount- it looks about the same.

I would definitely NOT reproduce this in a model, can't imagine it would have any benefit, but can imagine all sorts of problems.

Paul
Paul Willenborg is online now Find More Posts by Paul Willenborg
Reply With Quote
Old Sep 08, 2002, 10:43 PM
Registered User
Keremeos, BC, Canada
Joined Dec 1996
632 Posts
Upthrust

Yup, sure has upthrust. However, I would look at the airfoil as well (something I haven't done yet even after building a couple). The airfoil is THICK (25%?), but the datum line has a truckload of incidence as well, so the mean upthrust is... well, I guess I better drag out the drawings.. again...

On the model, I suggest that it a thin airfoil, small incidence, some downthrust, would give you a dependable model. Scale is wonderful, but we, as modellers, must take liberties in the interest of success.
Terry Lyttle is offline Find More Posts by Terry Lyttle
Reply With Quote
Old Sep 09, 2002, 04:34 AM
Master
ChrisP's Avatar
Weilbach, Germany
Joined May 2001
2,467 Posts
Upthrust is no problem. The Twinstar has significant upthrust and flies very well. Hand launching is a dream.

I am also in the early design stage of a Halifax model. Span 1587 mm, AUW ca 1325 gms with 4 x Speed 400's. The aerofoil will be thinned to 15%.

I have done a vast amount of research on the Halifax recently and have decided on the Merlin version with the 'Special' nose and the later square shaped fins. There are SO many versions of Halifaxes to choose from. The D-Day glider tugs with the black and white stripes also look great.

The best book you can get on Halifaxes IMHO is 'Halifax Squadrons of WW II'.

Cheers !

ChrisP
ChrisP is offline Find More Posts by ChrisP
Reply With Quote
Old Sep 09, 2002, 07:59 AM
MAAC 6251
Ottawa, Ontario, Canada
Joined Jan 2002
699 Posts
It's interesting that your doing a Halifax too Chris. Will the wing area be about 3200 sq. cm.? What are making it out of, foam or balsa? I'm kind of leaning towards a bit bigger size like about 2 meters or so, but it's still early in this project. Heck, we're still flying, the snow hasn't even started to fall yet. Nexus has a plan for a Halifax with four 15's (2.5 cc) that I'd like to see.
I agree with the book you mentioned. It's by Jon Lake. A lot of these were used by RCAF squadrons so ,being a Canadian, I'll probably pick one of those. I think I will like a latter mark, one with the radial engines.
With the motors close to the C of G I guess the upthust won't cause a pitch change. Is there a significant difference in trim between power on and power off on you Twin Star?
RobZ is offline Find More Posts by RobZ
Reply With Quote
Old Sep 09, 2002, 08:30 AM
Master
ChrisP's Avatar
Weilbach, Germany
Joined May 2001
2,467 Posts
The net wing area I worked out is 3016 sq cm. You were right on !

Build concept is a 10 - 12mm blue foam 'coffin' for the fuselage. Shaped foam at the top starting at the underside of the cockpit (if you have been studying Halifaxes you will know what I mean). Wings hot wired from blue foam.

I bought the big Nexus Halifax R/C plan, but it was a bit too large. It's also not very scale. I also bought their Halifax scale plan pack which is very good. The C/L model would make a good basis for an electric RC model.

No trim change noticeable on the Twinstar.

Drop me an e-mail if you want to get into Halifax specifics.

Chris

PS - If you've got the book you will notice that there is not one single picture of a Halifax with Merlins with the 'special' nose and rectangular fins, all in one aircraft, although the 3-view drawing suggests they actually existed.
ChrisP is offline Find More Posts by ChrisP
Last edited by ChrisP; Sep 09, 2002 at 08:46 AM.
Reply With Quote
Old Sep 09, 2002, 08:50 AM
Registered User
Bill Glover's Avatar
United Kingdom, Bracknell
Joined Nov 2000
11,706 Posts
I believe the up-thrust on the Twin Star is only there to make hand-launching (even) easier ... a bit of 'vectored thrust', just like a Harrier with the nozzles tilted slightly down for a 'rolling' takeoff

Certainly I removed it all when I re-engined mine, there was no real trim change with power beforehand and none afterwards.

As Rob says, the closer the motors are to the CG the less pitch-trim effect there is from up (or down) thrust. If the motors pointed vertically upwards (90 deg upthrust) but were right on the CG there would be no pitch effect at all (they would just be trying to lift the whole model vertically upwards). So a few degrees of upthrust an inch or two ahead of the CG will make no discernable difference.

Many WW2 bombers cruised in a very 'tail high' attitude (the Whitley was an extreme case of this) and I imagine the motors were aligned to point straight forward in level flight, for maximum efficiency. Quite possibly this would look like up-thrust relative to a fuselage datum line.
Bill Glover is offline Find More Posts by Bill Glover
Reply With Quote
Old Sep 09, 2002, 09:01 AM
Master
ChrisP's Avatar
Weilbach, Germany
Joined May 2001
2,467 Posts
Quote:
Originally posted by Bill Glover
Many WW2 bombers cruised in a very 'tail high' attitude (the Whitley was an extreme case of this)...
Bill
My Dad flew Vultee Vengeance target tugs at Gosport in 1945. They were designed as a dive bomber and were one of the few planes which flew visibly nose high. The incidences were chosen so they would dive vertically and resulted in the strange flying appearance during 'straight and level' flight.

Chris
ChrisP is offline Find More Posts by ChrisP
Reply With Quote
Old Sep 09, 2002, 09:31 AM
Registered User
Bill Glover's Avatar
United Kingdom, Bracknell
Joined Nov 2000
11,706 Posts
Quote:
Originally posted by ChrisP
Bill
My Dad flew Vultee Vengeance target tugs at Gosport in 1945. They were designed as a dive bomber and were one of the few planes which flew visibly nose high. The incidences were chosen so they would dive vertically and resulted in the strange flying appearance during 'straight and level' flight.

Chris

Interesting, many full-size aircraft do have a characteristic 'sit' in flight which is often lost when modelled (I guess due to changing the wing section and/or incidence angle).
Bill Glover is offline Find More Posts by Bill Glover
Reply With Quote
Old Sep 09, 2002, 11:13 AM
Master
ChrisP's Avatar
Weilbach, Germany
Joined May 2001
2,467 Posts
Et voila !
ChrisP is offline Find More Posts by ChrisP
Last edited by ChrisP; Sep 10, 2002 at 02:29 AM.
Reply With Quote
Old Sep 10, 2002, 05:17 AM
Registered User
Bill Glover's Avatar
United Kingdom, Bracknell
Joined Nov 2000
11,706 Posts
Excellent, you can clearly see the funny wing incidence (looks almost negative, relative to the fus. centreline)!

And on the Whitley pic. you can see the huge positive incidence on both wing and tail.
Bill Glover is offline Find More Posts by Bill Glover
Reply With Quote
Old Sep 25, 2002, 08:26 PM
MAAC 6251
Ottawa, Ontario, Canada
Joined Jan 2002
699 Posts
I have decided to make my Halifax (or Halton) 72" ws, 576 sq. in. and 60 oz. auw. Power from 4 S400 motors geared 3:1. & or 8 cells CP2400.
Rob.
RobZ is offline Find More Posts by RobZ
Reply With Quote
Old Sep 25, 2002, 08:41 PM
Scott Black, Montreal
sblack's Avatar
montreal quebec Canada
Joined Sep 1999
1,254 Posts
Quote:
Originally posted by Bill Glover



Interesting, many full-size aircraft do have a characteristic 'sit' in flight which is often lost when modelled (I guess due to changing the wing section and/or incidence angle).
The pitch attitude of our models is often different that the full scale counterparts because we don't fly at 30000 ft with a wide range of aircraft weight. We fly at almost see level and at 1 weight and cg.

Let's not forget that the angle of attack would change drastically between low level and 20000 ft, and also that picture could well be showing a light aircraft, as opposed to one full of fuel and bombed up. They were probably nose high at the beginning of a mission and nose low at the end, assuming they weren't shot to hell.
sblack is offline Find More Posts by sblack
Reply With Quote
Old Sep 25, 2002, 10:59 PM
Registered User
Joined Sep 2002
7,938 Posts
Just fly a Multiplex Cargo. It has 0 degrees thrust and climbs under power so badly that a lot of people stalled them on take off. I have one and it's converted to a B-17 and I had the same problem. Didn't crash on take off, but almost. Adding 2 degrees of down in the motors helped, a little down trim too, it could have been more.
My Titantic B-29 is a kit and it's motors have about 4-5 degrees down thrust and it still has a tendency to climb under full power but is much better than the Cargo. I couldn't imagine setting up a model with 2 degrees up thrust. You'll find that you will need down thrust especially if you plan to ROG. Just my experience, hope it helps.
U812 is offline Find More Posts by U812
Reply With Quote
Old Sep 25, 2002, 11:01 PM
Registered User
Keremeos, BC, Canada
Joined Dec 1996
632 Posts
Halibags

We have a few old Halibag/Lancaster crewmen here, stories coincide about performance. The Lanc drivers used to say, "poor bastards" when they overflew a group of Halis, and most of the Hali crewmen here became POWs. The performance difference gave the Lanc a 7,000' advantage, ie, the Halis were down in the thick of the flak (13,000') and took a pounding, while the Lancs dealt with the night fighters. Bad times, sad times for all involved.

I build the Halifax for two reasons: one, the arrogance of a late-war Hali driver who told me that ALL Halis were scrap by 1946, so I build with the Halton nose and the '48 Airlift pannier, then show him the photos. Two, the model is easier in the fact that the stab/rudder is higher (less damage-prone) and the glazing is simpler than the Lanc. As far as variations are concerned, how nuts to you care to go? I would still like to see one close up, any variant, though.
Terry Lyttle is offline Find More Posts by Terry Lyttle
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Handley Page Halifax Started :) RobZ Scale Kit/Scratch Built 9 Oct 01, 2006 12:22 AM
Up Thrust on a top mounted EDF? RobZ Electric Ducted Fan Jet Talk 9 May 04, 2003 01:10 PM
Up thrust; not down! jrb Power Systems 36 Oct 12, 2002 10:22 PM
Up thrust----Side thrust LawDog101 Parkflyers 2 Dec 11, 2001 04:33 PM
CHARGER PROJECT FROM OPENING PAGE OF EZONE! HEADS UP!! Chris Rust Power Systems 2 Jul 16, 2001 11:10 PM