SSDR aircraft design

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SSDR aircraft design

Postby craigrhopkins » Sun Aug 18, 2013 9:12 am

Greetings All,
have just joined the LAA really with a view to the design and building of my own low and slow plane. While it would fall into the SSDR category, I would like to make sure it is designed and tested properly so that # take offs = # of controlled and intended landings.

I see that there are some courses at Coventry university coming up and while they look interesting, I don't think they are really what I am after which would be something like a "beginners guided to aircraft design". There is also the LAA engineering service but haven't been too successful with that yet so not 100% sure what happens there.

Anybody used either of these courses/services or have something else they can recommend?

I have purchased a few books listed in the library and worked through these as best I could... while they have been helpful one message I get from these is - get experienced help!

My thanks
Craig
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Re: SSDR aircraft design

Postby ian herdis » Tue Aug 20, 2013 12:14 am

Hi. Craig

Have a look at the DVD course by Bill Whitney. It's available in the book shop.

It's a very detailed course and all topics are presented in a very accessible way.

Good luck with your project.

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Re: SSDR aircraft design

Postby Ian Melville » Tue Aug 20, 2013 6:35 pm

Hi Craig,
I am in a similar position to you, and have done the first five Coventry courses, and am signed up to do the next three

You have made a good start by getting the books from the recommended reading list, but you also need to design section of the LAA website as there are some useful tools available. I would spend some time looking at other FAR103/SSDR and ultralight designs, even buying the plans if need and get to learn from how others have solved problems. Go around the Rally(you are going aren't you :) ) with a camera and take pictures of fixtures fittings and design elements that you think will be useful.

Learn the design codes like CS-VLA, BCAR section S. I know SSDR need not comply with any of them, but I think it would be a big mistake to ignore the majority of their content.

Cheers
Ian M
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Re: SSDR aircraft design

Postby craigrhopkins » Wed Aug 21, 2013 9:44 pm

Thanks both...

have ordered the Whitney DVD's so will work my way through these.

I have only been to two local airshows but planning to go to the one in a week or so's time. Will definitely have my camera all ready :)

I have got a couple plans where I would like to beg/borrow/steal ideas from so happy with that. Will follow up on the codes you listed but was hoping that the LAA would have a guide of some sorts for new members crazy enough to want to go down this route.

Enjoy Coventry - won't be able to attend unfortunately.
Thanks again both
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Re: SSDR aircraft design

Postby Ian Melville » Thu Aug 22, 2013 7:31 pm

Hi Craig,
There is some guides on the LAA website, but there is no step-by-step Noddy's guide to aircraft design. Aircraft design by the enthusiastic amateur in very new. I can only recall one UK home built design that did not involve a professional designer at some point (Clutton FRED). Brian Hope may correct me on that :oops:

SSDR has opened an new door, and everyone is still finding their feet. Two things I have learnt are:
The more you know, the more you realize how little you do know.
and
It will take longer than you think.

Cheers
Ian
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Re: SSDR aircraft design

Postby craigrhopkins » Thu Aug 29, 2013 10:52 pm

:)

Agreed - the more I read and learn the more I realise how many ways you could end up in a nasty mess if you don't get it *all* right!

Not looking for a noddy guide - but was hoping for a point in the right direction so thanks for the suggestions all. Downloaded and have read through the various design standards.

The Bill Whitney DVD pack arrived the other day so working my way through that. Thanks.

Also spoke to the LAA today and that was helpful. Nice guy. Unfortunately they don't have a mentoring or formal consultation process - yet! He did recommend another book which would be helpful. Bit of reading ahead so looking forward to that.

All good thanks...
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Re: SSDR aircraft design

Postby TRAZZELL » Fri Aug 30, 2013 6:22 pm

Take a look at Dan Raymer's book on prelim aircraft design and his web page (http://www.aircraftdesign.com/) - some useful information there.

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Re: SSDR aircraft design

Postby ian herdis » Sat Aug 31, 2013 12:42 pm

Craig

This could be good timing for you. Have a look at the flyer forum topic. CAA Bomshell For Micrilights.

If it is implemented all single seat microlights will be deregulated. So no need for you to design to SSDR with the wing area and wing loading figures which are very restrictive.

Not sure what some companies with think as some have invested heavily in SSDR

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Re: SSDR aircraft design

Postby Brian Hope » Thu Sep 05, 2013 10:02 am

Hi Ian, I have spoken to a number of people involved with 115kg SSDR and thay have all been very positive about the probability of the weight limit increasing/stall speed option. Building to 115kg is not easy and as one current manufacturer told me, it has taught them to think and build light, a mindset that will carry over to the new limits.
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Re: SSDR aircraft design

Postby craigrhopkins » Thu Sep 05, 2013 10:28 pm

Interesting stuff all of this...
Good to know at this early stage. Thanks again all for the input.
This probably doesn't change to much of what I had in mind.... but it sure opens it up and there should be some fantastic planes coming out in due course. Can't wait to see some of them...
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Re: SSDR aircraft design

Postby ColinC » Sat Sep 07, 2013 7:43 am

One immediate impact, should the change happen, will be that a great number of ultralights which are operated successfully elsewhere will be legal here. This month's LAA magazine raises some obvious concerns about that. However it does appear to mean that designs would be available to us and perhaps a lot of the motivation to design from scratch is not so relevant when you can take an existing design and legally tailor it to your needs.

The downside would be that instead of getting the input and vast experience of the LAA Engineering team behind it, the builder is on his own. Personally, I think that de-values the aircraft as the LAA approval and oversight means a lot to me.

It would be interesting to know if your interest in designing an aircraft stems from a burning urge to design, or is it because you cannot currently find one you can fly here that matches your needs?

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Re: SSDR aircraft design

Postby craigrhopkins » Wed Sep 11, 2013 9:14 pm

Interesting thoughts there Colin. LAA approval and sign off means a lot to me. Perhaps people will end up with the option of working closely under their guidance or adapting something else with little input from them. My one thought would be about insurance but I'm too green to even guess how the change impacts that.

Regarding your question - I guess it is a bit (or a lot!) of both. I have several designs floating round my head (don't we all?!?) and starting off on a low and slow single seat SSDR type would prove a great foundation and learning experience. With a bit of luck something closer to a real airplane with better performance could come down the line and benefit from this design experience. I have enjoyed the Bill Whitney DVD's (despite the DVD's getting stuck in certain places) and am now putting together something based on the formula's he provided. (So far his formula's have suggested I get into a gym!)

At 6'4" and well north of the 86kg design limit, I struggle to fit into a lot of the planes that I have been lucky enough to sit in - and would exceed the seat limit weight on those that I could fit in. Linked to this I'm ploughing cash into the business so that rules out the moderately priced and more expensive planes out there for a few years. I need something that is genuinely cheap to construct and operate (or as close to this as possible).

Besides the above waffle.... why not? Would love to understand how aerodynamics and materials and structures all work and affect each other. Everything is a decision and a compromise. With a resource like the LAA available there aren't many excuses left to not go ahead :D
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Re: SSDR aircraft design

Postby Brian Hope » Thu Sep 12, 2013 8:31 am

Though the article in the latest magazine does include some notes of caution about not disregarding the airworthiness and design integrity of an aircraft simply because it is deregulated, I hope the enthusiasm of the LAA for this proposed change in the SSDR rules was also apparent. We encourage low cost flying, that's what we are here for, and the proposed SSDR regime, with its useable weight and performance criteria, offers some real opportunities both for existing and new aircraft designs.
If there is one area we have some concern about it is for those who do not want to be out on their own and would prefer to operate within a Permit to Fly (or similar) regime, either because it gives them confidence that their aircraft has suitably experienced people keeping an eye on it, or it retains value in their aircraft because it is of a known, proven provenance.
It is however, unlikely that owners will have that option, my guess is that all existing single seat microlights will become deregulated at the stroke of a pen. At the Rally Mike Barnard of the CAA, commented that provided the Consultation was positive they would want to roll out the changes asap, possibly as soon as the NEC Flying Show at the end of November.
This is an issue that is being considered by LAA Engineering and they are looking at how we can best offer support, both to owners who wish to have some sort of continued airworthiness oversight, and those who wish to design/modify deregulated microlights. As of this moment we do not have a specific answer on how this might happen, all I can say is that our desire is to support our members in making safe and sensible choices - if they want that support. The very essence of deregulation is that you are free to make your own decisions; but as the article says, with freedom comes responsibility.
A comment in the latest Minimax newsletter suggests that with the Minimax likely to become deregulated owners could now raise the design all up weight from 268 to 300kg. No suggestion of considering what effect that would have on the undercarriage, the integrity of the airframe, performance, etc etc. It was just a question of putting more weight in because nobody would be able to say you couldn't. When the designer lays down a max all up weight, and an airworthiness approval process confirms that weight to be appropriate, I have to ask - is it responsible to ignore that max all up weight with no design investigation to assess whether it would be safe to increase it?
I think we have a potential issue with some people considering that the UK Approval process, as overseen by LAA and BMAA, is some kind of irrelevant and unnecessary burden on their freedom to fly what they like. It is not. It has kept UK pilots safe for decades, whether they be flying microlights or light aeroplanes.
If I may offer my own view as somebody who welcomes this new category with open arms - aeroplanes fly, and fly safely provided they comply with certain rules of physics, and those rules of physics do not know whether an aircraft is regulated or deregulated. All UK Approval does is ensure that the appropriate rules of physics are in place to ensure a structurally and aerodynamically safe aircraft. It would be folly to ignore the physics just because there’s nobody there to enforce your application of them.
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Re: SSDR aircraft design

Postby ColinC » Thu Sep 12, 2013 2:22 pm

Thanks Brian,

I think that I sit firmly in the group of people that appreciate the security that the current LAA approval and the airworthiness regime provides. I don't think that it's in any way wanting to have someone to blame if something goes wrong, it's all about having the backup of people with the proper experience and knowledge to avoid it going wrong.

For example, I have as you know an interest in the SD1 Minisport. It now looks as if it will fall out of the LAA system so from what you say above, it is not beyond possibility that I could have Santa drop me one off at Christmas. The reality is that will probably happen for a few people because there are a number of people impatiently following progress, some of whom do see the current rules as impeding their pleasure. Arguably, because the aircraft is being operated in various other places in Europe it could reasonably assumed to be fit for purpose, but as we all know, Francis Donaldson and his team have a reassuring habit of improving most things they look at in some way or other, and the inspectors ensure the quality is there. I would in reality prefer to wait for it to go through the LAA system as I appreciate the added value that gives but not everyone will agree.

If this proposal goes through, there is clearly going to be a role for someone, hopefully the LAA, to provide a framework for oversight and backup for those wise enough to know that they need it. Obviously those that think they don't need it will go there own way and nature or physics will have its way with them should they transgress.

My initial thoughts were that if I were to want to construct and operate an SSDR and, as we have discussed before, were to harbour a desire to design a simple aircraft, I would appreciate having a peer group around me willing to offer guidance and critism.

We do need somehow to find a way of organising something at that level, as the aims of de-regulation are exactly aligned to the original mission of the LAA in providing safe, affordable flying for the masses and we should embrace the opportunity.

regards,

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