My NACDeC-V journey
My
NACDeC-V journey
Designing an Amphibian Aircraft for Fire Fighting purpose
I always love to get
involved in some projects as it gives me a straight reason to learn more and
specific. By chance I got one similar opportunity while I was in my first year
of Mtech in Jain University. It was 1 week that our class has resume to offline
mode and I was excited being into the University for my Mtech and energetic at
the same time to meet with my new faculty members. One day we received a
message in our newly created official whatsup 1st year Mtech group. One of our faculty put that to ask students if they are interested
to participate in a National level aircraft design Competition as organized by
the IIT Bombay. Few of us has shown interest.
But since he wants only a group of 5(maximum number of member) and want to include from Btech as
well. So he asked us to send him a write-up stating our academic details and a
paragraph on why we want to be in the team. He might be asking this for he had very little or no interactions with us being the new academic batch and
hence are unaware of our nature. Infect not only he, we (those who had shown
interest) too are not much familiar with each other. As asked, I mailed him my write-up.
Then he created a group where initially he listed all students that has shown
interest (5 of us). One day during the lecture, he stopped the subject and
started questioning the (interested) students what we know about aircraft
designing and whether we have done any similar project in past years. It happens
that two of us had little experience of the same competition: 1) Me and 2) Ω
My
past NACDeC:
When
I was in 5th semester in Chandigarh University. Our HOD has
circulated similar notice. There too I have shown interest. The circulation was
about making a team with initial rough (sketch) possible design following the
requirement of the respective NACDeC and meet him. There were 2 teams that had responded and one was
mine. Actually, because I was interested so I personally approached my worthy
friends and requested them to be in my team. Most of them rejected but with lots
of effort three friends agreed. It was NACDeC-2 and the
requirement was about designing a High altitude long endurance aircraft
(lighter than or heavier than aircraft) for coastal mapping (3800km and at 15
to 20 km altitude) taking LIDAR (of 30 kg) as a payload. We did a rough sketching taking configuration from existing aircraft (our sketch was based on similar existing
aircraft called Zypher i.e. High Aspect ratio with hybrid power plant). Both
teams were being questioned regarding technical aspect of the design and how
logical is it as per existing technology. We got selected. In that competition
we cleared 1st stage. For 2nd report which needs to be
little technical, but didn’t submit the 2nd report as it was uncompleted
because the team members losses interest in between and did no work. While I
have to blame for that as it was I who requested them to be in the team and they
were not by their own. So I was a bad team leader than. The one benefit outcome
for me was that I watched the entire NPTEL lecture on aircraft performance and
static stability analysis of Prof. A.K. Ghosh and also lecture on design of
fixed wing unmanned aerial vehicles by Dr. Subrahmanyan Sadrela. And I think
the motive of Prof. Pant to starts this National Competition at its core was to
motivate the students to learn and explore Aerospace.
Come to present:
He extensively questioned both of us regarding the tools
we are familiar with and the aspects of aircraft designing. That day was little
embracing for both of us particularly for Ω. Later that day he finalized our
team: Me, β, Π and µ. Π was in replace of Ω and that too
only because he told our mentor that he know FEM (Finite Element Method). Ω was
disappointed because he had a serious doubt on Π’s claim. He also
blame me for disclosing that he had once participated in the competition
knowing which he was brutally questioned about aircraft designing. β didn’t
face that because she has not attented any class till then. I am not aware of µ
and why he selected her.
I was made the team
leader and an official letter was sent to the NACDeC committee with four of us (Me,
β, Π and µ) as a team members.
Me as a Team leader and
the progress of the report
The date of submitting
our first report was near so I called for a meeting. I wanted to know the area
of interest of other members as I know very little or not at all about other
team members. I have read the official notification and its requirements and had
already informed the others too to read the same. But in the meeting I found
that β and µ haven’t gone through the notification and Π didn’t even attended
the meeting. This was our first meeting and a member is already not punctual.
Later I search him and found that he was setting in the next class and doing
some other stuff. Actually he was designing an airplane (In CATIA) to show the team and
wanted to lead the team for the same (Internal team politics). I was happy that he design that airplane
and even officially being the team leader I was ok to follow anyone who has proper
insight of what we need to do. Seeing at his design I got little curious and because he wants to lead the team, I sincerely asked him if he has gone through
the notification and the requirements. He answered “Yes” and then he added that
he has design that in CATIA based the requirements for that competition only. But the layout of
the design was like that of a passenger. I than asked how can we use this as an
amphibian aircraft for fire-fighting purpose because its layout is that of a passenger
aircraft (cylindrical body with passenger seats and windows, mid-wing and
conventional tail). Then he surprisingly replied- Why fire-fighter? With little
more conversation we came to know that he too had not gone through the official
notification and its requirements. On that day I was planning to complete the
“Road map” which was one of the major requirements for stage 1 report. But all
this conversation took all hour (Yes I was not good at time management).
One of the reason I allowed him to present his design despite knowing that it
doesn’t make sense was because I wanted to make the team feels open to their
design ideas. On that very day I came to know that Π informed the mentor he is no more interested in the project hence will not continue. I couldn’t
make him feel interest than after so I asked other team members to feel free
with their opinion on all matters regarding the project.
Stage-1
(Initial Conceptual Report):
Stage-1 is the first
stage of the competition where all teams are being asked to submit a 15 page
report (excluding cover page, abstract, contents and all other lists, acknowledgments and annexures). For those who will be
participating for the first time, they might have lots of doubt about the
content of this stage-1 report (as no one wants to get knocked out in the first
round) and actually NACDeC team does organize a webinar just to brief the
requirements and to clarify the doubts but as an experienced I want to express
my opinion on what stage-1 is (this is just my opinion and doesn’t reflects the
actual evaluation criteria of the NACDeC for 1st stage).
The ‘must’ needed work in
the 1st report is the road map, mission profile, time line and task distribution
among team members. Yes you can modify in future as your design progress. By
‘road map’ they mean- How are you going to conduct this conceptual designing?
From where you going to starts and how it’s going to proceeds and come up with
a design as per requirements? You are asked to make a symbolic design approach
but not a long paragraph explaining how you are going proceeds. I think one
small paragraph is acceptable but a block diagram will be sufficient.
They will ask you to mention a 'Time line' based on which your report progress will be evaluated in future rounds i.e. to check if
you are ahead or behind your own scheduled time hence helps the committee to
judge whether you will be able to do your task on time.
Task distribution is I
believe to check if you have sufficient members to handle all aspect of the
requirements.
Then a brief write-up on-
what you think might be the various problems and challenges that you are going
to face (Based on the requirements) and possible solutions (as per you),
existing models and generalized specifications (not compulsory), feasibility of
the design etc.
What is being not asked
to do here? The answer is, we are not asked to come up with final layout
(actually with any layout) or do any mathematical analysis but just sufficient
enough to let the examiner know that you are familiar with the requirements and
the approach to be taken.
We
discussed what should be our road map and came up with one (we did changed with
the progress of our design not because we had changed our approach but because
the 1st block diagram was lack in basic flow representation).
We missed the time line
in the report 1. Actually I miss-interpret the road-map as our timeline. But it
was the goodwill of the committee that later they asked us to submit that externally
via mail.
We
had no doubt that we will not qualify the 1st round and by 3rd
of January we received the same.
Yes, regarding our fourth
rebelled member I want to mentioned that we haven’t message the committee because
we had no one to replace and informing the same might even leads to
disqualification due to lack of team members.
2nd
stage (MTR-Mid Term Report):
For MTR we got 3 months of time. The competition itself
span for about a year starting from the September where they released their RFP
(Request For Proposal), but actual working period, from ICR (Initial Conceptual
report) to FDR (Final Design Report) is about 6 month. Lot of uncertain
events has happened in between and lead me to a breaking point. 1st -due
to 3rd wave of Covid-19 our offline classes were cancelled and all
hosteller were asked to vacate the hostel, 2nd- Internal tests in
between, 3rd- the mentor left the college and didn’t informed us, 4th-
µ was too busy in her semester work and politely informed the team, 5th- β was out of reach.
For our new mentor, I called one of our
professor and explained him about the competition. He
accepted my proposal to become our new mentor. Than following the procedure I
manage to assign new faculty mentor for us. For other uncertainties I had no
control of so politely work alone on the report as per the timeline that is
being submitted in 1st phase. At the cost of few point in my CGPA, I
was able to somehow complete the MTR as per the timeline and then submitted on
31st March (last date to submit). I must say that although there was
no one to give feedback or questioned the analysis which triples the time for
the work but I had a wonderful time exploring the literature and techniques.
By 26th April the result for the MTR came and
luckily our team “HAS BEEN CONTINUED” for the 3rd stage.
If you will asked what is
to be included in the 2nd report? Here comes the timeline that you
have submitted in the ICR (stage-1). In that timeline you are being asked to
mentioned your work flow i.e. work flow between ICR and MTR and between MTR and
FDR. If you couldn’t meet your own timeline it can lead you to disqualification
(not necessarily) as the committee will consider that you are behind your
scheduled time and might not be able to complete the work.
The contents of our
report-2 were: Literature survey, Mission profile, configuration selection and initial sizing
(including Hull), power plant selection and initial layout.
What I haven’t done in
report-2 were: Performance and static stability analysis, structural layout,
cost estimation and optimization.
During this MTR, the
NACDeC team revised their requirements as one team (from the participants)
pointed out some requirements in RFP that might be either difficult or impractical
to fill. If I am not wrong than it’s the range (and endurance), one of the
mission requirement was to do 10 number of passes between water source and fire
points without refueling.
So because of this
changes, I too have to revisit the mission profile and then correct the range
and endurance accordingly. Luckily I haven’t done range analysis and fuel
estimation in MTR. Hence, few changes organized my MTR.
As I have received “HAS
BEEN CONTINUED” mail. I was happy. But afraid at the same time as my final
exams too were approaching and still lot many works was still left to do.
3rd
stage (FDR-Final Design Report):
Aircraft Design: A Conceptual by D. Raymer is obviously
as good reference book for this competition but I found that the book: General
Aviation Aircraft Design by S. Gudmundsson more specific regarding the design
approach. I followed the same. I want to mention here that if you are not aware
of your near expected values than there is ample chance that you could analyses
wrong figure which in my case was due to units. Those analysis hunted me even
after submitting FDR because occasionally I used to check if I made some mistakes
(yes it won’t help me to correct the mistakes if found) and sometime when there
is even a small differences my heartbeat raises but then again reevaluating
converges the number as per the report. I can sleep peacefully.
FDR was totally numerical
analysis. I have learned a lot in the process specially where things can go
wrong. Because this is just a conceptual design so for the numerical analysis
we have to assume few values and because I haven’t done any CFD analysis so my
analysis was a mixed of assumed values from literatures which I also have to
logically pick in such a way that they represent my model at approximate. Finally
I came up with few numbers some of which satisfied the requirements some of
them didn’t and as per me I have done all things right except two small
mistakes:
1) If
you ever come to my FDR report. Go to page no. 30 there I have mentioned that
the airfoil selected is NACA-4415 while I have actually selected 2415 (which I missed to update) but the
wrong thing here is the sentence itself. The correct sentence for the same
should be-
“ …We have chosen 2 & 4 series because
of cambered reason, 4 as 2nd digit because we expect that shifting
the maximum camber behind might improve our flow separation characteristic and
15 to 18% thickness as it has to operate at low speed hence as per Raymer
reference it the best.”
2) In
the cost estimation table we forgot to update the working hour’s data, because
initially we estimated assuming that the number of aircraft to be manufactured
in 5 years span is 500 but doing online research we found that for this kind of
aircraft the market demand is not that high. So later we estimated our cost assuming
100 but forget to update the Working hours column.
On 30th June I
was able to complete the report, check its order and submit. However our report
lack in structural layout and few more necessary analysis.
Our FDR includes:
literature survey, mission profile, configuration selection and initial sizing,
power plant selection, Hull design and scooping mechanism, performance
analysis, static stability analysis, cost estimation. The report ends with a
compliance matrix.
On July we received a
mail from the NACDeC committee stating that- “…your team has been shortlisted
for the final round.” Can't get more surprised.
We than had a webinar
briefing about the presentation round which was organized on 20th of
August. We were asked to submit the PPT to avoid any technical delay during
presentation.
20th
August (Presentation round):
It is compulsory that all team members should be there while having the presentation and the first question that was being asked in the stage was: Where is the fourth member?. Three of us went there. On that day there were two
sessions. Morning session was kept for seminars on hot topics in Aerospace in
India which includes Testing and certification of HTT 40 and HANSA NG,
presentation on SWIFT, design and testing of IJT for spin and on swarm drones. Those
were wonderful presentation. During our breakfast in AeSI one of my most
unexpected event occurs. I saw Shri A.S. Kiran Kumar Sir among the distinguished
guest. I took the opportunity and take a photo with him.
After lunch it was the presentation
round and all 5 teams were there including judges and other prominent
personalities. It was an honor to present in that stage. Our team were the
first to give the presentation.
Rules of the presentation
were pretty simple:
1) You
have 10 minutes to present your 10 slides
2) 2
minutes could be extended but not more than that
3) Than
judges (5-6 in number) prominent personalities and expertise in their field in
the nation will ask questions starting from what you have included in the slides
than going deeper to check the logic and understanding behind your analysis or
assumptions.
4) The
time frame for the Q&A round is 18 to 20 minutes.
5) Question could be asked to any members.
Few questions that was
asked to our team were (I am rephrasing the questions):
1) What
is the basis of initial configuration selection?
2) What
is the logic behind selecting the design point in constraint diagram and what
happens if we shift the point left or right?
3) (Since
our design point was close to the curve) Your design point shows that your
aircraft doesn’t have enough power to climb to service ceiling (Which was 6 Km
as per requirements)?
4) What
kind of speed (IAS or TAS or EAS) you have considered while doing performance
analysis?
5) What
is the reference of Cd0 value?
6) What
analysis have you done from the drag polar?
7) Why
the number of engine seems higher (our proposed design has 4 number of engine)
as compared to similar existing aircraft?
8) Have you done compliance matrix if yes than where is it?
9) Why you have considered those parameters for hull design and its reference?
10) Have you considered the sudden change of CG at the time of water scooping?
11) Why your neutral points seems too far?
12) How you have modeled hydro-dynamics resistance and where did you use it?
13) What
is the use of v-n diagram?
14) Was there any exciting or new things that you have come across or learned about?
We were able to answer satisfactorily (more or less) most of the questions except Q3 and Q11. It was an honor to stand in that
stage. We completed our presentation in due time.
I want to share about the
content of the slides for the presentation (based on my experience) which was
pointed out by the examiner for all the teams.
1) Includes
the relevant and important analysis
2) Don’t
forget to include the compliance matrix
3) Make
it readable even to the last person in the audience
4) It
is advice to do first slides presentation by any one member from the group for
time management. However questions can be answered by any member from the
group.
5) If
you don’t know the answer or got confused, it is batter to say “can’t recall at
this moment” rather than trying to act smart.
By
“important” I mean: configuration selection and 3-D views including isometric
view, constraint diagram, graphs and diagrams from performance analysis, power
plant selection, static stability derivatives, structural layout, any special
requirements, cost estimation and compliance matrix.
You can tradeoff the most
important one from the above and compress them in 10 slides (maximum). Rest you
can attach as an extra slides (but will not be allowed to show during 10
minutes of presentation) which can be referred to answer any specific question
from the judges.
Slowly other teams too
had presented their proposed design. All of them have presented very well.
Results were announced
within 15 minutes after the last presentation and we remains among the top 5
but was not in top 3. I can say this with certainty where we have missed. It’s in
the report. We have done most of the required analysis but not all of them.
Tips for the
participants:
1) Don’t
think that one or two members alone can do all the work.
2) Always
try to include members from the required expertise.
3) Competition
is very specific regarding the requirements, doing extra but undermining the
required one will cost you negative points. I would like to phrase this as- Do
what is being asked but not what you want them to tell.
4) Keep
patience and motivated, do the work every day to complete the task, you will
not affect your academic life. Enough time has been provided for the report.
5) Don’t
underestimate the usefulness of the tools like- MATAB, excel (I have done all
my optimization using excel and inserting data manually), CAD software and more
importantly if you use LaTeX for documentation it will be more convenient (I
have used MS Word hence extra effort to keep the document organized).
6) As
it is a conceptual designing, proceed your design based on feasibility and reliability
which will come from the literature survey.
From team Fire-Fighters
NACDeC-V
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