Isaac's Spitfire

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

Arthur Brown

Well-Known Member
Joined
May 1, 2016
Messages
139
Location
London
Does anyone have info to share on the Isaacs Spitfire, a UK origin 66% wooden scale(ish) Spitfire? Even is there a set of plans out there?
 

plncraze

Well-Known Member
Joined
May 11, 2006
Messages
2,152
LAA in UK sells the plans on cd. There is one for sale on barnstormers now. Pricey. Isaacs wrote about construction in Sport Aviation in the mid-seventies. Even he was intimidated by the spar.
 

spitfirebuilder91

New Member
Joined
Jun 17, 2018
Messages
1
Location
Penicuik
What do you want to know about it?

60% scale, all-wood, Continental O-200 power. Only three that I know of have flown - G-BBJI, G-ISAC and one other example in America (which is/was for sale the last time I heard) that has a Jabiru up front. Built by a chap called Bill Pratt.

I have a set of plans for it myself, which I do intend to build someday.
 

rasco

Member
Joined
Jan 27, 2021
Messages
15
LAA in UK sells the plans on cd. There is one for sale on barnstormers now. Pricey. Isaacs wrote about construction in Sport Aviation in the mid-seventies. Even he was intimidated by the spar.
What do you mean by "Even he was intimidated by the spar"?
 

plncraze

Well-Known Member
Joined
May 11, 2006
Messages
2,152
Isaacs did not have a lot of money or space to build and the spar required both. He taught at a school so he built the spar there during a long holiday and he sold the Fury to pay for the lumber. The spar was a box section that was tapered both in thickness and in height. He was limited by money and time and was relieved when it was finished.
 

rasco

Member
Joined
Jan 27, 2021
Messages
15
Isaacs did not have a lot of money or space to build and the spar required both. He taught at a school so he built the spar there during a long holiday and he sold the Fury to pay for the lumber. The spar was a box section that was tapered both in thickness and in height. He was limited by money and time and was relieved when it was finished.
So he was intimidated by the spar because it was big and complex => expensive to build. He was not concerned about its safety, right?

Updated:
I believe this is the spar:
 
Last edited:

plncraze

Well-Known Member
Joined
May 11, 2006
Messages
2,152
It is an interesting book. He was involved with Dr. Winter's Zaunkonig. He also was involved with Mr. Currie and a few Wots. Plus his own work.
 

flitzerpilot

Well-Known Member
Joined
Apr 19, 2017
Messages
230
Location
Hirwaun, Aberdare, S.Wales, UK.
It was Ray Hilborne who carried out the stress analysis for the Isaacs Spitfire and also for the previous Fury. He also provided some further (post-war) analysis for the pre-war Currie Wot, built in 1937. He was also responsible for the design of several of the aeroplanes for Those Magnificent Men in their Flying Machines and the Pfalz in Blue Max. He designed the Supermarine S.5 replica of Schneider Trophy fame, now being built anew by Bill Hosie Jr. and team and the full-size wooden Spitfire prototype replica built by Clive DuCros. Ray's input across the decades provided great support to homebuilders and the industry alike. One design which benefitted from his skills was the prototype Flitzer Z-1.

John Isaacs was himself inspirational to later designers such as myself by designing the Fury (he went on to design the full size wooden wing for a 1:1 replica Fury, still flying I think) and he viewed the prototype Z-1 on its first roll-out at a PFA Rally some thirty years ago, giving me the 'thumbs-up' and a beaming smile. Tragically he was unable to speak as he was suffering from throat cancer, from which he later succumbed.
 

rasco

Member
Joined
Jan 27, 2021
Messages
15
Does anybody know what is Isaacs Spitfire's stall speed and stall characteristics? I would like to read a PIREP too. Must be very interesting reading.
 

fly2kads

Well-Known Member
Joined
Jan 2, 2010
Messages
1,843
Location
Justin, TX
EAA's book on aircraft woodworking includes two articles on the Isaacs Spitfire, one on construction, and the other a flight report. The original articles should be in the EAA's online magazine archive, but I haven't looked them up. From the reprint in the book, the stall speed is 47 MPH with the belly airbrake deployed, and 52-54 MPH clean. The description of the stall is:
"Stalling was innocuous, there was no real buffet warning but the stall was indicated by the nose gently pitching down accompanied by a slight wing drop. An accelerated stall was indicated by snatching of the ailerons - this can be encountered if you are over enthusiastic doing aerobatics."

The overall tone of the PIREP is very positive, and the test pilot particularly enjoyed doing aerobatics in it.
 

rasco

Member
Joined
Jan 27, 2021
Messages
15
EAA's book on aircraft woodworking includes two articles on the Isaacs Spitfire, one on construction, and the other a flight report. The original articles should be in the EAA's online magazine archive, but I haven't looked them up. From the reprint in the book, the stall speed is 47 MPH with the belly airbrake deployed, and 52-54 MPH clean. The description of the stall is:
"Stalling was innocuous, there was no real buffet warning but the stall was indicated by the nose gently pitching down accompanied by a slight wing drop. An accelerated stall was indicated by snatching of the ailerons - this can be encountered if you are over enthusiastic doing aerobatics."

The overall tone of the PIREP is very positive, and the test pilot particularly enjoyed doing aerobatics in it.
Thank you very much. Is it this EAA's book?
 

plncraze

Well-Known Member
Joined
May 11, 2006
Messages
2,152
If you are an EAA member you can access these articles in the Sport Aviation archives section. John Isaacs wrote a number of articles about his planes.
 

rasco

Member
Joined
Jan 27, 2021
Messages
15
I am not an EAA member. I am not from the US. Can I become a member though?
 

rasco

Member
Joined
Jan 27, 2021
Messages
15
Yes, that's the one!

Here is the PIREP. It looks like it originally ran as the last of a four-part series by Mr. Isaacs.

And yes, anyone can become a member of EAA, regardless of location.
Thank you very much!
 
Top