80% Scale Hawker Hurricane

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CBHurricane

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I'm wondering if it'd be possible to create an 80% scale version of a hawker hurricane using an LS engine similar to the 80% P51 that has been built. Not sure the exact name of the person who built it, but found an engine runup video on the forum while reading everything I can. Being new to designing and building airframes and the affects of downsizing aircraft designs, I'm curious if it's plausible. Would the airfoil have to be reworked for a 20% decrease in size? I've been trying to read and catch up on as much of the scaled warbird topics as possible to catch a glimpse of design alterations; in so doing I found that with scaling aircraft down the biggest items affected are usually tail sections having to be enlarged, airfoils thicker or different altogether, and weight to power ratios. I've found these cases in reading the threads of the member who had the Hurricane 103 project, and the threads on basically all P51 scaled derivatives. With regards to scale Hawker Hurricanes, has anyone here built or have knowledge on design aspects of the flying legends and if the design was altered from the full size? I ask this as to my knowledge the Sindlinger Hurricane as all to scale as a 5/8 replica except a 4" wider and taller canopy and 12% larger elevator. I'm currently in no way at the point currently to start a project like this immediately, but always like thinking about potential projects and possibilities....maybe a 10 year project start date to have completed for retirement.
 

Voidhawk9

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Maybe. What is the Hurricane airfoil and how does it perform at lower Reynolds numbers?
 

Riggerrob

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Possible.
85 to 55 percent seems to be the smallest you can scale down a World War Two airplane before the cockpit gets too tight for a 95th percentile male pilot.
Yes .. the square-cube root law can bite you if you forget to enlarge tail surfaces.
Also consider increasing the leading edge radius to tame stall characteristics.
Also consider accident rates with original Hurricanes and young pilots. If you are designing for a private pilot, you might want to improve stability a bit. Robert Baslee had "tamed" scaled-down replicas of a dozen World War One airplanes by enlarging control surfaces and balancing them like modern airplanes.
May I suggest studying drawings of the Sindlinger Hurricane replica? It is about half-size, but several have flown successfully.
An Italian has also built an LSA Hurricane replica.
 

CBHurricane

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I am aware of the sindlinger hurricane and in the process of getting a set of plans to build one and have extra material to study over the hurricane and the effects of scaled down warbirds.

I've also emailed the Italian company flying legends in regards to the hurricane kit they produced. They have stopped production of their kit but do plan on providing a new kit out in the next 2-3 years. I'm curious if anyone on here has ever built their kit and what the build process is like, whether all aluminum semi-monocoque or a combination of truss built as well.

I'm also aware of a member on this form who was in the process of designing and building a "103" hurricane which I'm assuming is an ultralight at a 65% scale. I'm hope that member will see this thread and shed some light with his experiences of adjusting measurements. I do know he kept the Clark yh airfoil but changed the root from a 19% to 21%.

I am currently working on my private license, whether I go into commercial when I'm finished is yet to be determined due to that'll be a large lifestyle change from being an electrician currently.
 

pylon500

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At 80% scale, it's probably worth looking at the original structural layout and just scaling down.
Aerodynamically the Hurricane is really pretty basic with old fashioned sections and thicknesses. If built to todays standards of materials and considering it's not planned to carry armament, bombs or protective plating, an 80% size could almost come out at half the original weight and probably be pleasant and reasonably docile aircraft to fly.
I think the Flying Legends guys only ever built the prototype Hurricane before moving on to the scale Tucano.
I was looking into a lightweight version to fit into our (Australian) ultralight class of 600kg (1320lb) MTOW, having most of the steel tube structure replaced with aluminium tube and powered by either a Rotax 2 stroke or maybe a small (~2.5lt) V6. Mitsubishi actually made a 1.8lt V6!
Scale undercarriage will make you scratch your head.. 🤔 :oops:
As for lifestyle changes, you'll probably make more money (in the long run) staying an electrician!
Hurricane.jpg
 

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cluttonfred

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pylon500, the dimensions are a little hard to read, but your sketch appears to be just slightly larger than the Sindlinger Hurricane's 5/8 (62.5%) scale. The Sindlinger had a gross weight of 624 kg (1375 lb) with a Lycoming O-320, so with a lighter engine and a careful build it certainly ought to be possible to meet Aussie microlight rules depending on the stall speed requirement.

PS--Just for fun, I ran the numbers for a U.S. light sport aircraft based on the Sindlinger. The gross weight would need to come down to about 985 lb to make the LSA clean stall speed of 52 mph. Even going with a much lighter engine, fixed landing gear, reduced fuel capacity, etc. a 28% reduction in gross weight seems pretty unrealistic without significant redesign. In that case, maybe 3/4 (75%) scale would make the wing loading much more practical for an LSA.
 
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pylon500

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Yes, often smaller is not always better, the W.A.R. replicas as a case in point, many of those things were thought of as 'nasty little things'.
I've looked at 'little' aeroplanes like the Hummel Bird, the CriCri and others, and the thing I perceive is that they are hard concentration things to fly,and you breathe a sigh of relief once safely back on the ground?
Not the sort of flying I like to do (saying all this and hoping my current project comes out as a relaxed flyer, despite it's no nonsense, military look 🤔 ), hence I don't mind the idea of a larger, lighter built plane. Also a bit more impressive on the ramp!
I think Titan pretty well nailed it when they first brought out the original 912 T-51, even if it could only be a single seater (at the time) here in Oz.
I'm surprised the Sindlinger actually comes out that light, would be a real performer with an 0-320 if that's it's gross!
 

CBHurricane

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For a good set of complete technical drawings on the Hawker Hurricane, of as close a set as possible to scale down from would the A.L. Bentley drawings be the best option?


I also found this link which seems like it may supply even more technical drawings on the hurricane but unsure on the quality being that the format has been changed over the years.


I currently have the Haynes 'owner's workshop manual" and hawker hurricane inside and out by Melvyn Hiscock for what they're worth in regards to technical drawings and insight.

I have read this thread:
Hurricane Mk103
in regards to the power/weight/material/airfoil dilemma for a scaled down Hurricane and trying to sift through all related material as time permits. I'm curious how this project has progressed.

Pylon500 have you gotten far in your quest of a microlight hurricane? I'd love to follow along if you have a build thread or multiple pertaining to the design and engineering of it.

As a preliminary thought for some weight savings for an 80% scale using downscaled design and build of the original Hurricane; instead of separate joints to join the truss structure together id weld it, all the wood on the doghouse and other sections where practicable I'd replace with aluminum to save weight, having no armaments in the wings will help with weight savings and as mentioned no armor plating. New light weight electronics and avionics would shave some weight as well. Ideally it would be great to build it with about a ~200kn top speed.
 

TFF

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As practical as it seems, you just shut everyone off when you said weld it. 50% of the spec dream for this plane is bolt together. In the minds of many, they think they can build a fighter with a cordless drill and a claw hammer. You are squashing their dream to have a better aircraft at that size. 4130 tube would probably be better. If people are replacing wood fuselages of sopwith camels with steel tube, why not it’s grandson.
 

nicknack

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About the flying legend hurricane... I've asked the company about 2 years ago. The plane is a two seater and the fuselage is a metal truss(aluminum possibly ). I do think a larger ie 80% to full size hurricane will be a great two seater touring/cross-country aircraft. Attached a couple of pictures I have showing the truss fuselage and even on the early versions of the wings are fabric covered.


1611911787095.jpeg
Here's the cockpit of the flying legend 75% scale hurricane
1611911996004.jpeg
 

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Riggerrob

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Britain suffered form shortages of welders during World War 2, which is why all of their ships, tanks and airplanes were riveted together. Riveting allowed Britain to train up large numbers of semi-skilled factory workers to cut, drill and file many little bits and rivet or bolt them together. This manufacturing strategy also helped employ more factory workers ... keeping them gainfully employed reduced the risk of frustrated un-employed joining the British communist party. In many respects, the British ruling class feared their own working class.
This method made it easy to set up shadow factories to build sub-components. Several shadow factories were set up in Canada, Australia, India, etc. to build British pattern tanks and airplanes.
One advantage of riveted structures was that shot-out or worn-out components could be quickly replaced. The disadvantage was the much higher parts count and the need to precisely machine all those faying surfaces.

At the same time American industry had plenty of welders and could manufacture welding torches by the millions, to American ships, tanks and airplanes were more likely to be made of welded steel. American manufacturing methods used far fewer skilled workers to produce far more ships, tanks and planes. In many respects, WW2 was won on the farms and factories of North America.

If I were designing a Hurricane replica, I would start with a welded steel tub fuselage.
 

CBHurricane

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Thanks for the insight and knowledge everyone. I appreciate the extra phots nicknack as well, I'll add those to my ever growing collection of my Hurricane album.

TFF I have nothing against riveted joints.....yet, mainly as I've yet to experience doing thousands of rivets consistently and that tune might change or it may not. As Riggerrob has made note there was large workforces to accommodate the endless rivets compared to one individual.

Riggerrob is there a reason you would choose a welded steel tub vs one welded in aluminum?

I did recently receive my Sindlinger Hurricane plans which I'm ecstatic about digging into as it took almost a month total waiting for the mail delivery services between Canada and the United States. First order of business of this adventure will be to put other projects on a backburner to build a large enough print table/workbench to display the multiple pages of prints to ogle over.
 

Riggerrob

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Dear CBhurricane,
The choice of welded steel tubing versus welded aluminum tubing comes down to the tools and skills of the individual builder. More welders are familiar with steel than aluminum.
 

CBHurricane

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Dear CBhurricane,
The choice of welded steel tubing versus welded aluminum tubing comes down to the tools and skills of the individual builder. More welders are familiar with steel than aluminum.
That is true, I had in my head chromoly steel. Every welder I've talked to about it have never worked with it. They seem to be focused with mild/hss, stainless, aluminum, then chromoly for experience...may have something to do with the oil industry in my area. May just have to find the right person at a performance shop with that experience.
 

nicknack

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Hi, I believe most aircraft truss welders use 4130. Example would be the P51 replica from titan ie T51 which uses a 4130 frame with fuselage panels attached. By the way how complete are the sindlinger plans, are landing gears plans build or something that is from a known aircraft? And where did you order a copy? I am thinking of ordering a set myself. Of all the taildragger WW2 fighters, the hurricane is my favorite for a replica. Large wing area, wide landing gear and high up cockpit giving a good view outside taxiing, plus a tube truss fuselage.
 

wiloows5050

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The landing gear plans come with it. The plans are for a hand crank, mods have been made for electric and hydraulic. The mods were done individually by builder.

D095D11B-1E80-4FAB-AFE1-28BA8B7332DA.jpegCE183012-F877-4E47-A9E4-F8413000B891.jpegthe prototype a couple of years ago.
 

CBHurricane

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Hi, I believe most aircraft truss welders use 4130. Example would be the P51 replica from titan ie T51 which uses a 4130 frame with fuselage panels attached. By the way how complete are the sindlinger plans, are landing gears plans build or something that is from a known aircraft? And where did you order a copy? I am thinking of ordering a set myself. Of all the taildragger WW2 fighters, the hurricane is my favorite for a replica. Large wing area, wide landing gear and high up cockpit giving a good view outside taxiing, plus a tube truss fuselage.
I got my set of plans through Lyle Sindlinger for the hurricane. I haven't made my way through all the plans yet as I've been spending more time recently trying to source out the raw materials nearby. My build will be in a canvas type Quonset here in Alberta Canada so I've been doing the research of the temp/humidity changes affects on the sitka spruce and mahogany plywood as it's not insulated. Fingers crossed I can find someone local vs getting everything shipped through ACS as I've heard the shipping is astounding. I hope to find someone as well who has experience welding 4130 in my area as well as it may become an expensive learning experience.
 
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