THE SECOND SR 71

Just looking into ordering some materials to build another SR71 the same size as the first one ( ITS A UNFINISHED CHALLENGE FOR ME ) but this time 2 EDF fans and DEPRON
Simon and Tony have realy got me interested in this stuff
So something simple to start with

Brill! I'll look forward to it!

Will it be black depron then? Should be good,

Can you get black depron ?? will have to go through the threads and take in the information on them

grey will be fine Tony.

it was on my to do list, but i will let you go first

As far as I am aware true Depron is made only in dark grey and white. There are some other similar materials that are coloured but are only available in relatively small sized sheets.

The SR71 is not the most efficient shape for slow (100mph?) speeds so you really need all the EDF efficiency you can get so my advice is if you can to avoid using cheat holes.
In general fans are much more sensitive to aerodynamic disturbance on the inlet side than the exhaust so cheat holes are an inefficient way of getting a fan to 'breath' .

Do you know how the other EDF SR71s have arranged their inlets?

Dont know Simon but i cannot see a way of doing it without cheat holes other than leaving the cones off and thats not an option, maybe leave the bottom out off the cones and there will also be a 15mmm ring around the cone where it fits to the engine airframe

By the look of some of the foam SR71 on YouTube I looks like the inlet spikes are somewhat under size, They do also appear to have cheat holes (actually what I believe area air dump vents on the full size) certainly on the top and possible underneath as well.

My ideal solution would be to work out the area of the scale inlet 'ring' and then size the EDF FSA of the fan to match it. The fan may end up rather small but then a Depron airframe can be very light.

I note that at Mach 3.2 the spike was retracted considerably so from the outside it looked like it was rather smaller so it would still be scale with a smaller spike.
'SR71' in Wikipedia shows a nice diagram of how the airflow actually worked at different speeds.

Been trying to make contact with DEPRON FOAM but there seems to be a problem as i cannot get through to the , do you have a email address or phone number Tony
Also emailed Steve Webb but again nothing
Think ill be looking to fit 12 bladed fans in it as they sound so much better

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never had a problem before.

Could your difficulty be anything to do with it being Sunday here today, BB

Still looking forward to this one though

Garry

No i tried in the week ? maybe its my computer

Can we not help you by forming a link ? Like a relay station ?

Garry

Iv been cynoed, i found some new industrial stength cyno and as my BSI odourless had run out ( have to use odourless as cyno kills me but at $23 for two oz i use it spareingly ) i got some and tried it
Been very ill for a week now after useing it on the planking for the rockerbox covers on the spitfire
Thanks for the offer Garry i will try again today, i would like to get in touch with DEPRON FOAM the people that Tony uses as they seem to be about 30 pence a sheet cheaper than Steve Webb but cannot contact them so if anyone has a phone number for them, please

You have my sympathy there BB. I too am allergic to cyano and have to use the odourless/foamsafe stuff.