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« on: August 13, 2015, 04:35:30 PM »
sundaram
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Its been a while since I had bought the HK Pulse jet Engine. Its about time I got that in air.

I am undecided here unable to choose between three plans here from outerzone. I am sure Gusty will help in choosing one for me  Grin.

The three plans are

DELTA TOO Wing Span 36"
http://outerzone.co.uk/plan_details.asp?ID=6151

http://www.outerzone.co.uk/images/thumbs/plans/6151.jpg
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE
http://outerzone.co.uk/images/thumbs/models/6151.jpg
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE


LIL TOAD Wing Span 30"
http://outerzone.co.uk/plan_details.asp?ID=5897

http://www.outerzone.co.uk/images/thumbs/plans/5897.jpg
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE
http://outerzone.co.uk/images/thumbs/models/5897.jpg
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE


CLIMAX DELTA Wings Span 40"

http://outerzone.co.uk/plan_details.asp?ID=5875

http://www.outerzone.co.uk/images/thumbs/plans/5875.jpg
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE
http://outerzone.co.uk/images/thumbs/models/5875.jpg
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE


In all the three plans I need to majorly modify the fuse and the nose to facilitate the Pulse jet incorporation as well to to maintain Geometry.
As of now I am leaning more towards Lil Toad  reason being Symetrical aerofoil and I wanted to keep wingspan to under 34".

Gusty your comments are eagerly awaited please.
« Last Edit: August 13, 2015, 04:54:36 PM by sundaram » Logged

 

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« Reply #1 on: August 13, 2015, 04:42:55 PM »
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CLIMAX DELTA Wings Span 40".....
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« Reply #2 on: August 13, 2015, 04:49:03 PM »
sundaram
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Only for the benefit of uninitiated on Pulse jet
Images

http://www.hobbyking.com/hobbyking/store/catalog/34247main2.jpg
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE
http://www.hobbyking.com/hobbyking/store/catalog/34247s2.jpg
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE
http://www.hobbyking.com/hobbyking/store/catalog/34247s3.jpg
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE
http://www.hobbyking.com/hobbyking/store/catalog/34247s6.jpg
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE
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« Reply #3 on: August 13, 2015, 04:50:43 PM »
sundaram
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Thanks Saurabh Noted. Definitely it looks robust in construction. Anyway I will be reinforcing more.
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« Reply #4 on: August 13, 2015, 05:31:50 PM »
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Re:

Wow all the very best sir , its always been a dream to own a pulse jet Smiley
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« Reply #5 on: August 13, 2015, 05:39:12 PM »
sundaram
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Thanks Doc.
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« Reply #6 on: August 13, 2015, 05:54:16 PM »
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Sorry sandy

saw it now, will go with lil Toad for three reasons

(a) Sweep back is essentially a design fro super sonic flights, climax has less sweep of them all, she should glide better than the rest, coz it's going to be a engine off landing

(b) Twin fins and the support structure means least spanwise flow and less of tip stall, for the same reason high directional stability, means she will be locked  in on the run

(c) Thicker wing section means (a) High rigidity (b) Nice lift, she can float to super slow landing, not to mention inherent strength she will have

PS
Looks like need to put my pulse jet too to some testing
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« Reply #7 on: August 13, 2015, 05:55:19 PM »
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« Reply #8 on: August 13, 2015, 06:49:56 PM »
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be the first one to crash....



now this is going to be interesting...........   all the very best sundaram sir...
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« Reply #9 on: August 13, 2015, 07:07:33 PM »
sundaram
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Thanks Sanjay Sir, Gusty, and Jayant.
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« Reply #10 on: August 13, 2015, 07:56:31 PM »
sundaram
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Gusty let me elaborate on my term of reference and restrictions leading to the dilemma of choice. So you can further ponder over the choices and make a deliberate decision. Further request you to join me with the build if time and Balsa resource permits.

1. High Speed required as you would agree with pulse jet there is an inherent cooling problem if model is not fast enough and further valve pulse frequency does not peak well in low speed. So I am basically looking a very high speed profile.

2. Delta wing has inherent very high wing area. So keeping with requirement of speed I am looking at a max wing span of not more than 34" to keep profile small and less drag.

3.  Static Thrust claimed is about 1.6 Kgs and So I am looking at an final AUW of not more than 1.8 Kgs.  I am looking at achieving this AUW after Balsa Sheeting the complete wing surface and filming it and Lite Ply and Aluminium Taping just under the Pulse jet.

4.  I need to incorporate servo less under carriage fold-able tricycle since I am not looking at a Bungee launch or a ramp launch. So some Ply reinforcements at the under carriage base plate are required.

5.  Which ever wing I have to choose, I have to modify and incorporate a Twin Rudder fin on either side of tail pipe and further elongate the nose of the fuse to incorporate the nose gear, fuel tank and other electronics and to maintain symmetry for better CG.

6.  I have chosen these wings only to adopt the wings ribs profile and construction pattern. So even if I have to choose the Climax Delta I might drop the inner most ribs and reduce the span still from 40" to say 34-36"

As I look at it the three wings have following profile :-

https://lh3.googleusercontent.com/ePVB8HsaD5bPevJ2J4Lx_5k6LpZ3NBqVyl9cGNPsdFw=w370-h278-no
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE


To keep speed up my choice is now between a reduced wingspan of Climax delta of 36" or a Lil toad. What say gusty which one should I go ahead with. Very thin chord I might not be able incorporate a fold-able under carriage.  Head Scratching After all the research I am seeing myself back at Lil Toad 😃
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« Reply #11 on: August 13, 2015, 10:27:27 PM »
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Sir,
Anticipated speed 100mph/150fps?
Or more?

Take off ramp a la V2, or dolly, as alternatives to u/c?

When you post the video, i'll surely have the headphones on, to hear the music!

Godspeed on this project.
Regards.

PS:
There is a lesson hidden in your posts for all newbie electric flyers who think the thrust from the motor/prop must exceed the weight!
Your plan to fly a real jet at 90% power to weight ratio is proof of what i've been long propagating on this forum, namely, trainer models can easily fly on 50% power/weight ratio.

Looking forward to build log and video, after video of Papillon, which i suspect will fly like a jet!
Regards.
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« Reply #12 on: August 13, 2015, 11:36:46 PM »
sundaram
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Thank you very much for the best wishes Iyer Sir.

If it touches 100 mph I will be thrilled for sure sir.

Dolly is definitely a fantastic idea to do. Thanks for that sir. Without UC. It will have huge weight reduction.

I am too hoping a very tight and fast flight envelop for Papillon.

Regards
« Last Edit: August 14, 2015, 11:39:09 AM by sundaram » Logged

 

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« Reply #13 on: August 13, 2015, 11:50:56 PM »
sundaram
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Iyer Sir with your idea of Dolly, now choice is very clear that it is Climax delta with span reduced to approx 36 inches. Thanks. Will go ahead with that.
« Last Edit: August 14, 2015, 11:38:42 AM by sundaram » Logged

 

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« Reply #14 on: August 14, 2015, 12:14:31 PM »
sundaram
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Plans for Climax Delta Printed out. It came in about 56 A4 Sheets which when joined will for two A2 Size Plans. one for wings and one for fuse and fittings. Quite a detailed plan I must say. Sheet one with fuse detail is not of much use to me. I will be using only sheet 2 with the details of the wing profile and construction detail.

https://lh3.googleusercontent.com/d9ReCo7VDrtcP-P380RqwaPaoxjssXCVENvPH-kkqQE=w881-h643-no
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE
https://lh3.googleusercontent.com/2nTnbpvZv6HOYgxkkK6UfmzEcXNIWdZ0n-1gRw-xO2k=w869-h643-no
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE
https://lh3.googleusercontent.com/aqpkx4O1k1zpmcpwlsVQIrvF_Q3PO4OQrYOjIzB2GGA=w857-h643-no
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE
« Last Edit: August 14, 2015, 12:24:59 PM by sundaram » Logged

 

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« Reply #15 on: August 14, 2015, 12:45:31 PM »
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Going to be amazing build , I think . Following :-)
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« Reply #16 on: August 14, 2015, 03:37:36 PM »
sundaram
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Thanks Aditya
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« Reply #17 on: August 14, 2015, 03:39:50 PM »
sundaram
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Derived Data from one of the online wing loading calculators posted here. So I am not badly off here with the speculated dimensions of 34" span. Ideally I am seeing I should have kept myself at 30" only. Still no worries.

http://www.flyingsites.co.uk/downloads/wingloadcalc.htm  

https://lh3.googleusercontent.com/R4C-1hkMcZDcHb5GP3P27rmWI9STdp_B49vQuFUAOD8=w483-h643-no
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE




PS : Gusty your take on this invited. Correct me if I am very wrong anywhere.
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« Reply #18 on: August 14, 2015, 04:18:46 PM »
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Planned Modification to the Wing Profile and construction is as under.

With the modification to the span and chord length, I need to do a fresh CG calculations though.

https://lh3.googleusercontent.com/jxAsMoItcISVCck1u1uqI_qHub6UToR-2JnICIl9g5s=w684-h643-no
SCRATCH BUILD DELTA WING JET FOR HK PULSE JET ENGINE
« Last Edit: August 14, 2015, 06:43:03 PM by sundaram » Logged

 

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« Reply #19 on: August 14, 2015, 04:47:18 PM »
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Sir,
For a moment i feared that the wing cube loading would get too high due the size reduction.
But with round numbers like 64oz and 4sqft, it is easy to see that the wcl will only be 8.
At 16oz/sqft and wcl 8, shouldn't be hard to handle. (In 60-80mph range, that is)
Wonder how she'll handle at significantly higher speeds.

Curious about where you are planning to mount the motor...
Regards
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« Reply #20 on: August 14, 2015, 06:21:22 PM »
sundaram
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Sir with Wing dimension changed CG will have to re-estimated again. The Pulse jet is just about 400gms Plus and its heaviest Parts are  the intake valve area and combustion chamber. I will arrive at the rough CG of just the Pulse jet by balancing and will try to keep it slightly ahead of the wing CG spot of wing and then try to balance the wing at CG by adjusting remaining parts and the pulse jet. The Pulse jet will be mounted on Top surface with a gap of 1.5-2" between the combustion chamber and the top heat shielded surface. 2 Degree upthrust of tail pipe will be incorporated.
« Last Edit: August 14, 2015, 06:49:41 PM by sundaram » Logged

 

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« Reply #21 on: August 14, 2015, 06:25:19 PM »
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Re:

Wooo this thread is gonna a knowledge overdose with all the geniuses at work ... Enjoying every bit ....
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« Reply #22 on: August 14, 2015, 07:07:11 PM »
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Sir,
Hope you don't mind my pestering you with my curiosity.
The project is too interesting to stop queries!

Will the cockpit and fin be in the way?
Or will you delete cockpit, and replace fin with wingtip fins?
Does tailpipe upthrust mean the same as equivalent downthrust for the airframe?
Does the motor really glow red hot?
Will you use insulation (like asbestos) or reflection (like polished steel/aluminium)?
The 1.6kg thrust is static thrust or at typical (?) flying speed?
Does the thrust increase with speed?
What, in a pulse jet, is the equivalent of prop pitch? How to predict estimated speed?
And finally, is this the first attempt in India, or has someone already 'bin there, done that'?
Regards.

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« Reply #23 on: August 14, 2015, 07:50:40 PM »
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Sir you are most welcome to any number of times. I feel honored  Hats Off.

This being a first model for me too, each query is a refresher for me as well.

1.  I am not adopting any of the design & Plan of the "Sheet 1" which is basically the fuselage and how its merged with wing. I am just using the "Sheet 2" the wing only. I will be making a square box nose with sharp tip as indicated in the sketch to keep the fuel tank and electronics. Since its going to be box cross section, it will have more height than the chord thickness of wing but I will taper the rear end above the chord thickness sharp and flush with wing top surface and well before the intake of pulse jet to facilitate easy and good aerodynamic airflow to the valves. I will add some more sketch to elaborate the design planned. There will be no cockpit as such. For ease of construction I am not adopting any of the round nose design as in most delta pulse jets already used by other's in international scene.

2. Cockpit is deleted. Fins will not come in the way at all since the twin fins are going to the wing tips.

3. Yes Sir by the tail pipe upthrust you can say equivalent down thrust for the air-frame as well as a positive incidence for the wing surface.

4.  With sufficient airflow around the Pulse jet it will not heat up at all to red hot. Aim is to prevent that with speed.

5.  I am planning to use Aluminium tape over the ply surface may be two layers. No insulation like asbestos required sir, since wood as such too is a bad conductor. With good airflow nothing should be required.

6.  1.6 KG is static thrust and with gain in speed thrust too will peak. Design of Nozzle is such to increase fuel feed with increase in  air speed entry and air volume. Even the frequency of valve pulse too will peak. Upper thrust limits is limit less and can only be hypothetical.

7.  Theoretically Pulse jets can achieve limitless speeds unlike the props and the limiting factors of pitch of prop and its breaking effect of the airscrew.

8.  Is it a first time in India?? Can't really say but I will be thrilled if its first. Sir you have just motivated me a bit more by that query.  Grin .

Regards

PS : Incidentally Papillon came out to just 10.5 Oz/Sqft.  Giggle Its a glider too I came to know.
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« Reply #24 on: August 14, 2015, 09:46:23 PM »
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@rcpilotacro,
Gusty sir,
Where are you?
At least 2 guys (Col & me) await your inputs to this thread.

Its a different matter that all Indore flyers are waiting for you...
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