Aircraft Design and the LAA Magazine

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Aircraft Design and the LAA Magazine

Postby ColinC » Sat Feb 19, 2011 11:40 am

Hi,

I've finally found some time to look through the new 'Aircraft Design' pages and several of the documents provided there which are very interesting and informative. Also, FD's articles on Light Aircraft design have been equally informative and inspirational. I'm particularly looking forward to next month's article on engines.

Whilst I'm unlikely to ever be able to raise myself to attempt to design an aircraft, I thought that these articles represent a very public sign that the Engineering team are supportive of innovation and this is to be applauded.

I recently had reason to think that the LAA's Management had moved to a position that was not supportive of, and sometimes hostile to, individual designer's taking their proposals through the approvals process, but reading these documents and the magazine articles has done a lot to dispel that idea.

I do hope that the LAA will continue in this way to support innovation in aviation, a position which aligns well with parts of its published vision; 'the promotion of amateur construction' and values; 'Relentless pursuit of economical recreational flying without undue regulation or restriction'.

It was interesting to see that a large proportion of the most recent designs featured in FD's magazine article were from mainland Europe and the USA, and we in the UK do seem to have fallen behind in that area. I wonder how much that is due to a misconception that the UK is over-regulated when in fact we probably have a uniquely supportive regulator.

regards

Colin
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Postby Ian Melville » Sat Feb 19, 2011 1:10 pm

Hi Colin,
I don't think LAA engineering has ever been anti new designs or innovations. They do however require the designer to prove that the design meets specified standards for that class of aircraft, and that is where the problems start if you don't have a degree in structural analysis and/or aerodynamics. I don't think that is unreasonable.

IMHO this has caused the UK to slip behind the USA and Europe. If you need to hire in the skills that requires investment, and a return that can only be made through sales of kits. There is currently no incentive to sell a low cost plan design, rather than an expensive kit. We all know the latter is taking a business risk, which in the current climate is unlikely.

Over the last few years it has become increasing obvious that the future of light aviation in the UK can only be sustained by reducing the cost. So may be why there is shift in focus. I haven't had a chance to look at these tools yet but they will enable the guy in a shed to have a fighting chance of minimising costs. We need more support like this.

Last winter (09/10) I suggested to Brian Hope that the LAA put together some weekend training packages for budding designers. If you restrict it to LAA types with a conventional layout, I am sure degrees are not necessary. Perhaps a spin off from this would be to form design groups for those with a common desire?

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Postby Nick Allen » Sat Feb 19, 2011 1:53 pm

Hi Ian
I think your idea of an LAA design course is an excellent one -- perhaps Richard Mole could talk through how he's been doing it: a sort of lay-person's perspective.

If you need to hire in the skills that requires investment, and a return that can only be made through sales of kits.


I'm not sure that's the only business model that works. Take your Thatcher, for example: Thatcher has sold to date 454 sets of plans @ $360 apiece = $163,440. That's really not bad -- he could have afforded a stress engineer out of that! :D

(PS Jodel is back in the hangar now -- will be in touch.)
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Postby ColinC » Sat Feb 19, 2011 2:14 pm

Hi Ian,

I probably didn't put that point over well. I always knew that Engineering were supportive when reasonable proposals were presented, but never seemed to be offering encouragement. By publishing such documents they do seem to be actively encouraging people to consider designing aircraft which is a small but important difference.

Providing scrutiny over any new designs is not without cost to the organisation, but it seems reasonable to expend its resources on projects that could help provide more economical aviation opportunities for people being squeezed out by rising costs and the general economic uncertainty.

I don't know why we appear to have fallen behind the USA and Europe, but the aviation community in the UK is pretty small and there are still a few people doing some very impressive work.

Colin
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Postby ColinC » Sat Feb 19, 2011 2:35 pm

Hi Ian
I think your idea of an LAA design course is an excellent one -- perhaps Richard Mole could talk through how he's been doing it: a sort of lay-person's perspective.


I saw that Francis mentioned his name in that article.

I agree, and I expect that Richard will certainly spot this shortly and probably come round to beat me with a length of carbon fibre for saying this, but that's a very good idea!

I also met another interesting chap this week, Dave Bonsall whose Mark 2 version of his Mustang has just flown - see here:

http://www.youtube.com/watch?v=DcHGSFTZWeQ

http://www.youtube.com/watch?v=GkTkIRRSwDY

Dave would be interesting to listen too. He did all his own research, and designed and built that aircraft from scratch, then rebuilt it as the Mark2. It took a very long time but he is clearly a determined chap.

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Postby Ian Melville » Mon Feb 21, 2011 2:08 pm

Hi Nick, You are quite right that the CX4 would seem to be a profitable plan based design. I think you would have to be lucky to get that level of sales in the 2 seat market. It also helps if you have low cost design that looks just right. I wonder if there are any figures for sales of other designs? (completed is not relevent here).

I have had a slow morning so a chance to look at the design tools provided by the LAA. Looks like a good start and I shall be puting the CX4 numbers into it to see what happens. As always there are two areas that these tools and many of the books stop short, Stress and Stability. Is it possible to summerise these complex subjects? or at least to enable people to use tools like Strand 7? or physical load testing.

Another area that we need, and may be able to sort out between us is the weights of various bits and bobs that make-up an aircraft. For example the VW engine and what is included or excluded from that weight. AeroVee, GP etc quote weights be are not clear what assessories are included. It cannot be too difficult to set up a database with members input?

There is always the ADS software, but this isn't cheap to maintain.

Cheers
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Postby merlin » Mon Feb 21, 2011 2:26 pm

Nick Allen wrote:I'm not sure that's the only business model that works. Take your Thatcher, for example: Thatcher has sold to date 454 sets of plans @ $360 apiece = $163,440. That's really not bad -- he could have afforded a stress engineer out of that! :D


I wonder how many would have been sold if the first one had not had been from the US experimental system ?
In fact this system has led to a number of success stories such as the Vans line.
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Postby Nick Allen » Mon Feb 21, 2011 5:19 pm

I think the Thatcher plans have sold well because it's a very pretty aircraft, designed to be low cost, and the plans themselves are not too expensive -- I'm guessing that if you sell plans for around the £200 mark, you will get quite a few sales from dabblers (for want of a better word). But the maths raises the interesting question of whether one could persuade a suitable engineer to do stress work, etc., on a royalty basis -- might be a fruitful model methinks!

Edited to add: I came across this site the other weekend -- it's not a very well laid out affair, but there is much useful design information contained therein if you delve down some layers:
http://www.roymech.co.uk/
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Postby ian herdis » Wed Feb 23, 2011 6:55 pm

Regarding an aircraft design course I would recomend the DVD set from Bill Whitney (available in the LAA book shop) this is a series of lectures and some course notes, it is excellent, its a bit pricey but it is well worth it, Mr Whitney is a very good speaker and the DVD`s are very enjoyable and in that format if you are not sure about an aspect of design you can review it untill it sinks in !!!!

A few years ago I came across a designer (on the web) Dan Raymer he has a very good book ``Simplified Aircraft Design For Homebuilders``
the name say`s it all. I asked Dave at the book shop to source it for me, this title is now listed in the LAA book shop. It touches on structural calculations but makes it clear that it is only an introduction.

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Postby Ian Melville » Wed Feb 23, 2011 8:33 pm

Thanks Ian,
I already have your two reccomendations, plus several of the other LAA reccomendations.
Dan's book is good, but I was a bit miffed when I got to the Penultimate para of page 115. So just where are we supposed to turn for accurate stability calculations?
Bill's DVD was one of the first design tutorials I read/watched and I think I need to revisit them. For the price, I found the presentation a let-down (not the content)
Each time I read a book something more seeps into the old grey matter, though it also seems to seep out :D
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Postby ian herdis » Thu Feb 24, 2011 12:18 am

Well Dan does call it `Simplified` and we know there is nowt simple about it.

Bill`s DVD feels just like what you would end up with if say the LAA was to arrange a series of lectures on aircraft design, a really clever bloke in a portacabin sharing his wisdom with a bunch of dumb enthusiasts, great stuff.

I think in the end most people would require the services of a professional even if it was just to check and advise.

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Postby Brian Hope » Thu Feb 24, 2011 8:15 am

Hi all, I have discussed the possibility of a series of lectures on aircraft design with Francis and co, perhaps working up an SSDR as a case study. It is a possibilty, they are certainly interested, but working such a series into their busy schedule won't be easy.
Such a series of courses, let's say half a dozen day long sessions, isn't going to take somebody from zero knowledge to being the next Michel Colomban, but it would give a solid grounding in the subject for those with a passion to continue the quest for learning the skills required.
LAA has also recently purchased a design package aimed at the amateur designer, and use of this package as a design tool could well form part of a course, plus continued use of the programme for those going on to work up a design of their own.
It has to be said at this moment in time that we have no firm decision on this project, and if we proceed it will have to be on a commercial basis, as with our other courses. However, I do believe there is a desire amongst the membership for such a series of courses and it is therefore, an ongoing discussion.
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Postby Ian Melville » Thu Feb 24, 2011 1:59 pm

Hi Brian
I for one would be interested in such a course, and I suspect there are many others that don't inhabit this forum. Any chance of turning some of this thread into a readers letter or editorial comment for the next available mag?
I am guessing that the LAA has brought the ADS software package. I was quite impressed with it and it can be a big time saver. It was the annual costs that I found hard to justify. It was alo missing many of the smaller engines and bits of typical LAA aircraft. e.g. VW engines and microlight engines. That can be resolved though.
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Postby Ian Melville » Thu Feb 24, 2011 2:02 pm

Any chance of getting this tread moved to the new Design section?
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Postby John Dean » Thu Feb 24, 2011 3:12 pm

As requested. :D
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