FPV speed challenge

[Pasty]

I've changed the thread title to open this up as a general FPV speed fun thread.

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Was in the workshop with a mate last night building some planes and drinking a few shandies... I start messing around with a motor calc webpage to see how different props would effect our FPV wings (we're running the same powertrains)... the calc is pretty spot on in estimating top speeds, amp draws, flight duration etc.

While messing I then wonder what speeds I'd be able to get from my 3s 2200, the 25amp esc I have and a higher kv motor. A few clicks later and I find that with a 2200kv 25amp motor spinning a 5x5 prop will give me around 145mph on the flat...

Another few clicks later and I've bought a motor off Giant Cod while spouting how cool it'll be to ground bust at those kinda speeds.

This morning I realise what I've done, I didnt need this motor, yeah it'll be cool to fpv at those speeds but right now I could have done with other stuff for my money and to do this I'll need another vTX... bugger.

Oh well, its done now, time to find or design a homebrew FPV speed machine!

My adventure will be documented in this thread... let the fin begin. :D


Oh heres the motor I got...

http://www.giantcod.co.uk/2217-2200kv-brushless-outrunner-motor-p-402976.html

[Flypoppa]

I noticed that it is out of stock. Did you get the last one?

[Pasty]

yep! another thing that rushed me into the purchase while all excited.

[Coyote]

Lol, your on a roll with this pending lark Steve. Im impressed :)

This should be a fun project. So what flight durations are you looking at ?

[Pasty]

Its butt clenching ground busting speed I'm after duration is waaaaaayyyy down the list of prioritys :)

Prolly get 4mins or so of WOT... plenty to scare myself!

[sheep600fx]

Bloomin eck Pasty nearly 150mph!!! youve watched top gun too many times mate lol. Hope youve got good reflexes  :o

[Pasty]

Good reflexs = check :)

Whether I'll get close to the 145mph the calcs gave me is to be found out... I think the key to it is going to be keeping the plane small and light.

My flying buddy is going to make one with a similar powertrain so that we can chase and race :D

[Pasty]

hmmm done some reading and I think the calc must have been wrong... 145mph on a 25amp motor and ESC powered by 3s is way off me thinks.

Well the motor is on its way so let see what I can achieve...

[Shikra]

Nutter.

I'd say calcs wrong... But go for it

I managed 168kmh in my FJ. but that was with a bit of a dive and pulling 30  and a pan/tilt setup on top.

[Pasty]

I re-ran some calcs last night and 120mph is more of a real target... this is on the flat without a dive...

But now Shikkers has offered up a speed to beat... 104mph is the first mile stone :)

To maximise efficincey and thus speed the plane will be a conventional layout (less drag than a wing/delta) with prop up front (no folders here guv). The camera will be heavily recessed into the fuz to futher cut drag so the view out front isnt going to be great but thats not what I'm after and personally think that the lack of view will add to the racer feel :D

I was going to have a night out of the workshop but with the motor turning up today I'm thinking I might sneak down later and cut my wing cores :)

[Pasty]

ok, to give you an idea of what the planes going to be like, heres a nice design similar to what I was thinking... but with a camera with streamlined canopy on top ;)

A span of 30-40", the smaller it is the easier it'll be to make it rigid but the harder it'll be to keep the wing loading in check and fit the gear.



His build thread and plans:-
http://www.rcgroups.com/forums/showthread.php?t=118633

[Shikra]

Fast and Low - got to be good fun. Go for it. Looking forward to the vid already!

[mark1975]

i like your thoughts steve i would like to see a camera on a hotliner aswell or maybe something like my little favourite the st blaze by ripmax i love that little bird :)

[FPVSteve]

Remember to take a carrier bag for bringing it home :D

[g.collins]

PZ Habu + Radar Gun = 112MPH!!!

This it a speed test for a Habu Jet it reaches 112mh, are you shore that you will get that sort of speed, It will be craze controlling it with the tunnel effect of camera views