Verhees D1

[Geoff_H]

I have been trying to get building information on this aircraft.  I have searched the website but there is no information such as build materials, build time, pictures during construction etc.  To buy plans to find out information would cost 400Euro.  Id anyone building one or have a set of plans or bill of materials?

[onetrack]

Geoff, why don't you just email Bart Verhees and ask him those questions directly? Surely, if the gent is a reasonable person, he'd be happy to provide the answers to those basic questions. His email is in the last paragraph of the article below.

 

https://www.kitplanes.com/verhees-d2/

[Geoff_H]

Posted email to him two weeks ago.  No reply whatso ever.  I have since been researching the internet dailey.  Hence I am looking to this site.

[facthunter]

Every BIRD I've seen has a tail. Nev

[Geoff_H]

Did you notice the Concorde?  Aerodynamics designed by an Australian, Prof Tom Fink, an absolute genius.

[onetrack]

Every small delta-wing design seems to end up with control deficiencies at some point in flight, and I don't believe you could design them right out, to match the control level of the standard aircraft layout, that has been the most popular layout, for over 100 years. 

 

If there's no answer from the email address supplied, then perhaps a call to Verhees Engineering listed phone number may be more productive.

[facthunter]

So is the Birds designer I've been told but it was originally a Dinosaur.  Yes I've been up and close to a few Concords but they are SUPERsonic .Have you seen the high nose up attitude they land at?  Nev

Edited April 10, 2023 by facthunter

[Geoff_H]

Yes the D1 has a transparent floor to get better vision on landing.  Tom Fink tried to teach me supersonic fluid mechanics, my results could have been better, but from what I remember subsonic and supersonic Delta wing design is very similar.

[Geoff_H]

The Facitmobile second generation design uses flat panels, similar to stealth aircraft, however the for simplicity of design in this case.  The designer had worked for a company that designed the early stealth aircraft.

Delta wing aircraft are reported to be simpler with very large cockpit volumes.

[facthunter]

Sharp sweep backed Leading edges must give dutch roll  effects .Some of these require gyro stabilised yaw dampers on rudders. I used to be interested in weird stuff but what I want to fly is highly controllable Neutral stability plane with no real vices. NOT STOL either. Nev

[Marty_d]

Hang gliders have sharp sweep back and no tail.   Tips are negative incidence compared to the centre section.   Probably wouldn't translate well to a faster aircraft though. 

[turboplanner]

21 hours ago, Geoff_H said:

I have been trying to get building information on this aircraft.  I have searched the website but there is no information such as build materials, build time, pictures during construction etc.  To buy plans to find out information would cost 400Euro.  Id anyone building one or have a set of plans or bill of materials?

That's the dimensioned layout drawing.

Pick a file format that allows you to blow it up and if the dimensions are legible, take the file to officeworks, who can print a D Size drawing. (Can't rememer the exact dimensions of D Size - about the size of a big Drawing Board.

[Geoff_H]

Done that but the definition on the drawing has been lost.  I actually know the wing span so I printed the drawing to fit on an A4 sheet, found the scale then scaled most dimensions.  It is 8ft wide with wings folded up, found most other major measurements same way. So can guess the amount of aluminium needed, the website says "6061 or 2024" suggesting the craft could be made of 6061.

[turboplanner]

8 minutes ago, Geoff_H said:

Done that but the definition on the drawing has been lost.  I actually know the wing span so I printed the drawing to fit on an A4 sheet, found the scale then scaled most dimensions.  It is 8ft wide with wings folded up, found most other major measurements same way. So can guess the amount of aluminium needed, the website says "6061 or 2024" suggesting the craft could be made of 6061.

The two materials might require different interior material thicknesses, rib centres, number of supports etc.

[Geoff_H]

That is my concern.  The spard seem very thick and angled, is their construction different 

This is the part where the designer talks about the stability of the design and some interesting differences to the "conventional design"

https://www.verheesengineering.com/delta-aerodynamics/

[facthunter]

Anhedral may affect x wind landings capability,  Nev

[kasper]

On 11/04/2023 at 1:18 PM, Geoff_H said:

That is my concern.  The spard seem very thick and angled, is their construction different 

This is the part where the designer talks about the stability of the design and some interesting differences to the "conventional design"

https://www.verheesengineering.com/delta-aerodynamics/

When you read the linked page the designer has consciously made deign decisions to address control issues/concerns.

 

The area of dutch roll is the most 'worried' about delta/swept wing control behaviour because its not nice to experience.  But by lowering an already high directional stability with anhedral they reduce the cause of (and impact on flight behaviour) of dutch roll.

 

And I will come back to the trikes I have flown and own ... the stability of a swept wing CAN be massive even without vertical surfaces ... but generally comes at the cost of speed range.

 

The old XL wings (mid 80's design) had no vertical surface at all and with a lot of washout/twist in the wing were 50mph wings.   They took off, cruised and approached at 50mph +- 5mph.  Want to move outside that range and you need gorilla strength.  And as outlined in the Delta page linked any gust conditions were 'safe' in that the wing lowered AofA in gusts and maintained airspeed and altitude  ... at the cost of the control bar being moved around without your input in a trike.

 

Go into the medium performance wings like the Quantums (mid 90's design) and the stability had been traded off to get better speed range and generally higher speeds - 60-65mph +- 10.   These wings have small keel pocket 'fins' to assist with maintenance of directional stab ... but had low dutch roll and good stability.  The Raven wing in my profile pic is slightly higher performance than the Quantums but it actually has a real fin on the top .. . and when I was working with the factory on their next generation wing to replace the Raven they removed the fin ... and I added end plate wing tips above and below the wing to increase directional control and remove dutch roll that existed without them.  I quite like stability ... 

 

When you went up to higher performance wings (from around 2005 onwards) sometimes the trade of stability for speed is not as you might like whilst others went to significantly more complete management of the wing to get a balance eg active internal airflow management within the wing itself, variable geometry sweep, anhedral and wing tip vertical surfaces.  BUt you have a selection of trike wings out there that can comfortably cruise at 90mph+

 

What I am saying is that you do not NEED active control systems in a swept wing or a flying wing to achieve a good range of operations and a comfortable control/flight performance - they can be designed into the airframe.

 

Comments on this airframe and design:

1. it exists so it can be flown - its not vapourware or a product of marketing and sales of the 'next best greatest thing' but a hobby for the designer to sell the plans

2. it has a reflex aerofoil so its using a low/positive pitch section as you would expect

3. the designer in the web site is talking 'sane' about the issues and have they have been addressed - he is not a mad aeroplane designer

4. the talk of 6061 and 2024 ali in the construction is good to hear - they have different properties and their use is probably in line with use of their propertise in a logical way ... Never forget that 2024 is FAR more expensive and less workable than 6061 so using different alloys in different raw materials for different airframe components is to be expected.

 

I have liked this design from the first time I watched it on Youtube and if I were not building my own design flying wing I might have considered this.

 

But overall a flying wing can be very similar in its handling to a 'conventional' layout airframe.  there will remain differences eg do not hunt the stick in turbulent air in a flying wing, let it have a lot more freedom (similar to allowing the trike wing fly itself and the control bar has to given more 'freedom' than a conventional aircraft. 

[facthunter]

It's understandable you'd like stability with a weightshift plane. Coming from model plane flying I though so  too. Who wouldn't want stability? Could be inferred who'd want Instability? But it's not the same. Neutral  is better for extreme control conditions with 3 axis. Conditions you just wouldn't fly weightshift in..  Nev

[kasper]

20 minutes ago, facthunter said:

It's understandable you'd like stability with a weightshift plane. Coming from model plane flying I though so  too. Who wouldn't want stability? Could be inferred who'd want Instability? But it's not the same. Neutral  is better for extreme control conditions with 3 axis. Conditions you just wouldn't fly weightshift in..  Nev

Hmmm   

you underestimate the capabilities of trikes ... 45deg thermals everywhere and trikes amd 3axis all up n about ... or 45mph wind/dale straight down the runway and over 65 trikes fly in 

 

if you know how to fly them ie let the wing fly itself, you can fly modern trikes in almost any condition i would hop  into a jabiru or a22 and head off in.

 

[facthunter]

How do they handle negative G?  Nev

[kasper]

11 minutes ago, facthunter said:

How do they handle negative G?  Nev

Its outside the operating envelope ... but every trike pilot who ahs flown cross country in other than mill pond smooth air has experienced it in terms of transitory neg from a bump.

 

All the ones I have flown other than the xl ancient wings will handle transitory neg without any problem. 

 

You most definitely must not try to fly them neg (trike falling into wing is a certainty for funeral and an accident investigation report with adverse comment) but the neg that occurs in 'normal' lumps and bumps is fine.

[Geoff_H]

I am becoming very interested in building a D1.  It has a retractable steerable   monowheel with a tail wheel and small wing wheels.  The way that I read this thos aircraft cannot be registered in RAA and the pilot needs a tail wheel endorsement.  Am I correct in this?

[kasper]

44 minutes ago, Geoff_H said:

I am becoming very interested in building a D1.  It has a retractable steerable   monowheel with a tail wheel and small wing wheels.  The way that I read this thos aircraft cannot be registered in RAA and the pilot needs a tail wheel endorsement.  Am I correct in this?

No reason why it can’t be RAAus registered.  Int eh 19- cat it would be easily within the stall limits and undercarriage config has no impact on registration just who can pilot it as there may be a need for endorsements on the  certificate.

 

if you were looking to squeeze it into 10- reg then you are up against it.  As designed with the ea71 engine it’s too heavy for 10- and with a lighter engine you will need to deal with cofg