Sopwith Camel "tail heavy"

rexee · 5 February 2010, 06:48 PM

The "Camel" is often described as being "tail heavy"
Can someone tell me exactly what this means?

'14-'18aviationcollector · 5 February 2010, 07:15 PM

Hi Rexee,

Basically it means that the Centre of Gravity is further back than where it should be located, or another way of describing an aeroplane which is tail heavy is to say that the tail literally weighs more than it should in order to obtain the ideal Centre of Gravity, and as a result the ideal and safest flying characteristics.

I hope that's what you meant - you might have known that already. Chris told me that many First World War fighters were tail heavy, so they could climb quickly.

Regards,

David.

RobW · 5 February 2010, 07:27 PM

My interpretation is that in most phases of flight... especially cruising... you have to hold a bit of forward stick... Therefore the tail seems heavy.

Rob

rexee · 5 February 2010, 08:11 PM

Thanks for that explanation. Does the "rigging" of the aircraft effect the CG and the "tail heaviness"? I seem to recall reading about a pilot having his aircraft "rigged tail heavy"

Regards
Rexee

'14-'18aviationcollector · 5 February 2010, 08:11 PM

Hi Rob,

Well that is true too. Because the Centre of Gravity of a tail heavy aeroplane is behind the Centre of Lift (or is it Centre of Pressure?) the tail feels heavy. Downward trim and / or forward stick is required for level flight. As a result of the tail feeling heavy, the aeroplane would tend to want to climb constantly, and would resist any command to dive. Having an aeroplane which is tail heavy does not provide ideal flying characteristics, to say the least. If a choice had to be made between having an aeroplane which is tail heavy or nose heavy, a slightly nose heavy aeroplane would have superior flying characteristics to a slightly tail heavy aeroplane.

Cheers,

David.

'14-'18aviationcollector · 5 February 2010, 08:21 PM

Hi Rexee,

An aeroplane can be rigged to be or at least to feel tail heavy or nose heavy to a degree, but in the true sense of the word tail heaviness or nose heaviness refers to the design of the aeroplane, the location of the Centre of Gravity relative to the Centre of Lift (Pressure?) and the physical weights of all of the components in the nose and tail of the particular aeroplane.

If the fuselage (and not all First World War fuselages could be rigged this way) or more specifically the wings were rigged to effectively increase the incidence of the mainplanes, thus bringing the Centre of Lift further forward, the aeroplane will effectively be more tail heavy. I think a lot of "tweaking" was possible and practiced on First World War aeroplanes. The angle of a lower stub wing for example was fixed but the centre section of the top wing is a completely different story. Its' angle of incidence could be varied, at least slightly. A design such as the Bristol Fighter, which admittedly is unusual could probably be rigged in such a way that both the upper and lower mainplanes could have their incidence varied I suspect.

Regards,

David.

DamianL · 5 February 2010, 08:47 PM

Hi

Earlier Sopwith designs, Strutter and Pup, had an adjustable incidence tail plane. A trim wheel in the cockpit actuated a worm wheel or recirculating ball screw (need to check drawing) in the tail which raised or lowered the leading edge of the tailplane, thereby increasing or decreasing lift from the tailplane.

From a quick look at a Camel drawing, the gap between the upper longeron and bottom of the fin, is larger than the width of the tailplane. Can anyone advise if the vertical position of the tailplane leading edge in the gap was adjustable?

Is this then how the pitch was trimmed as described, by adjustment of the tailplane leading edge, and thus small adjustment in lift of tailplane?

Regards

Damian

RAF56_Ball · 7 February 2010, 12:35 AM

Quote:

Originally Posted by '14-'18aviationcollector

Hi Rexee,

An aeroplane can be rigged to be or at least to feel tail heavy or nose heavy to a degree, but in the true sense of the word tail heaviness or nose heaviness refers to the design of the aeroplane, ...
If the ... wings were rigged to effectively increase the incidence of the mainplanes, thus bringing the Centre of Lift further forward, the aeroplane will effectively be more tail heavy...David.

Hi David,
Just a technical point here. Your first statement was pretty accuate. What followed though needs a slight modification.
Increasing the angle of incidence does not move the center of lift, it increases the angle of attack, thereby increasing lift but increasing drag. That does, however, cause a little bit of the feel such as you have described.

A "tail heavy" airplane is one where the CG is behind the center of lift (or COP - they are nearly synonymous to all except an aviation physicist), thereby requiring the tail to generate positive lift to maintain level flight.This makes a aircraft more maneuverable in the positive 'G' mode because it is less stable, meaning a small input effects a greater rate of movement of the horizontal axis (or pitch). It can rach a point, though, were there is not enought elevator authority to regain a nose down moment. And should a stall occur, it may become impossible to recover. The modern design of CG forward of C/L means that a stall will cause the nose to drop, hopefully leading to recovery of lift and contorl of flight even if all the pilot does is let go.
A second advantage is that lift needed to fly is created by generating lift in both the main and tail planes, relatively drag neutral. This is more efficient. A "normal" (in modern terms) 'stable" design means that negative lift must be created to maintain level flight, at the expense of needing more lift from the main planes to stay flying, with comensurately higher drag.

RAF56_Ball · 7 February 2010, 12:39 AM

Quote:

Originally Posted by DamianL

Hi

Earlier Sopwith designs, Strutter and Pup, had an adjustable incidence tail plane. A trim wheel in the cockpit actuated a worm wheel or recirculating ball screw (need to check drawing) in the tail which raised or lowered the leading edge of the tailplane, thereby increasing or decreasing lift from the tailplane.

From a quick look at a Camel drawing, the gap between the upper longeron and bottom of the fin, is larger than the width of the tailplane. Can anyone advise if the vertical position of the tailplane leading edge in the gap was adjustable?

Is this then how the pitch was trimmed as described, by adjustment of the tailplane leading edge, and thus small adjustment in lift of tailplane?

Regards

Damian

Simple answer is yes, but makes me wonder why they gave it up?

gipsymoth236k · 7 February 2010, 12:11 PM

As an intentional design, a 'tail-heavy' fighter is inherently 'unstable' in pitch which provides for GREATER maneuverability - good in a dogfight! Photos of in-flight Fokker Dr.Is, D.VIIs, and D.VIIIs often show the elevator in a slightly 'downward' position requiring a bit of forward control stick from the pilot during faster speeds. This design also allowed another benefit at slower cruise speeds during 'patrol' flights - precious fuel savings thus resulting in increased patrol range. With slower patrol speeds, the pilot's control stick could be placed in a more 'neutral' position to help lessen pilot workload and fatigue.

Regards,
Gary Sewall