Is ballooning a thing with any tiger moths???
angle engine slight down???
Or mix in on radio.....
It seems it isn't a issue with plane....just a conceptial part of flying Tiger Moths>>?????

The engine already has down-thrust built in. It is a feature of the under-cambered wings, similar to how pure "Clark-Y" airfoils change trim (climb and decend) with minor changes in airspeed. Symmetrial and semi-symmetrical airfoils have less of this problem.

Has anyone tried to modify the ridgid landing gear by adding working struts either in compression or tension???
Rafeek

Well the kit comes with functional struts, they aren't ridged.

Whose kit?

Well this is about the hangar 9 20cc tiger moth right?

Anyone NOT ridged???
Mine are and will never move unless modded.
Not needed

But of course its about the Hangar 9 Tiger Moth and its not a kit.
Its landing gear is authentic looking but has no give in it. A hard landing could bust the underside...
The original had compression springs. Thats why Iam asking if anyone has modified his.

I used Dubro 4 1/2" inflatable tires for mine. That has given plenty of "give" on landing with no problems. Just land it nice and gently!

Thanks neighbor.

Why couldn't you call it a kit, lol. There's only one 20cc H9 tiger moth geez Louise. The point is they don't produce that "ARF" with a rigid undercarriage unless I haven't heard.

Tissoy, when u go shoping at a suppliers web site u click on ARF or KIT. There is no category called ARF KIT.....
The reference to a rigid landing gear vs a functioing landing gear should be simple. I will leave it to you to figure it out.

Do you mean to say that you completely did not understand anything I said in the previous post? No, I would like your complete description of what rigid and functioning gear really is because obviously I have no clue. Then you can explain what is an ARF since you have the answer. If you can do that I will give you an award! lol

Tisoy,

I think Rafeeki is referring to the solid gear on the Hangar 9 Tiger Moth 20cc ARF. The gear is rigid. No spring/oleo strut, no rubber bungees, no articulation or stroke, just rigid, welded gear legs with no shock absorption. I wondered about that, too, as my H9 quarter-scale Cub has spring-shock articulating gear, and I really love it. Cushy-cushy landings! Admittedly the Moth can be landed as soft as butterfly feet on a daisy petal, so I'm not sure they are necessary, but they would be cool. Spring/oleo struts would have set this model off into the top-drawer category, if you ask me.

Easy guys..... Perhaps the lack of sun exposure, has caused many to have depressed state of minds....???

I understood the question, the previous answer was my thoughts exactly, and couldn't have been stated more elequantly.
Thank you Gliderguy, for taking the time to do so....

does the h9 cub have springs inside a tube??? Post a picture..... The forum needs something other than gloom n doom.

This is a custom spring landing gear I concocted for my 1/5 scale cub. I might have to revert to a similar arrangement for the Moth.

Rafeek

Kochj, I don't have my Cub handy right now (it's out in the storage shed), but here's a file pic of the Cub gear. The covers on the diagonal struts conceal two tension coil springs, that retains the two-piece sections of the diagonals under tension when the gear articulates. On the Tiger Moth, the faired portion of the vertical struts would conceal a compression spring, with a telescoping strut that is held at full extension by the spring in flight. The spring then provides shock absorption during landing. The E-flite Aeronca Champ 15e had this type of compression spring gear, and it worked really great. You could really feel it on landing, as the struts compressed and the gear legs splayed slightly outward. You can make something like this out of steel tubing, if you happen to have oxyacetylene equipment handy.

http://www.rcuniverse.com/forum/atta...mentid=1953635http://www.rcuniverse.com/forum/atta...mentid=1953636http://www.rcuniverse.com/forum/atta...mentid=1953638http://www.rcuniverse.com/forum/atta...mentid=1953637

Brilliant comparison.

Anyone have a internal shot of the shock? (the mech. of how it is held together and works)
on a piper cub?
The Tiger Moth has a covering over the "shock" right?

Rafeeki
I like the arrangement you have for the gear on the Cub. If I am reading the photo correctly, the springs are in compression when loaded, not tension. That makes a huge difference in the operation. I have a Dave Patrick Super Cub where the springs stretch in tension under load. One or two hard landings and they take a permanent set due to overstretch. I now use stretched O rings for the spring, and they last a while longer. I plan to make a similar arrangement to yours on a Rascal 110 I am working on
Ric

Its worked really well. It ceratinly puts a limit to how much the landing gear may spread after that first or second bounce. Note that when I put it in under some compression to eliminate any slop. It is a very inexpensive way of dealing with the problem. I picked up few springs from Lowes and am playing with the idea for the Moth.
I also covered the springs with a heat shrink tube used in el. work. Hit it with the hair dryer after I positioned it. Keeps the springs clean of exhaust fuel. You can see them in the pic not already slid in place.

I was also thinking about a sprung undercarriage. Then, some of the videos I see of the plane taking off in windy conditions, there is severe weathervaning and torque reaction (roll + yaw to left).

Maybe a sprung undercarriage would have a negative effect on this behavior - this is a lightly-loaded bi-plane after all. If wind gets under a wing, and the U/C gives in one-sided, there will be a divergent situation pretty fast/
(I have a 1/4 Cub with sprung U/C and have experienced this...)

So, it is possible that H9 chose to make it rigid for better takeoff and crosswind control.

Like already said, the plane can be landed at walking pace, very softly. I would probabably check instead whether an inflatable-type of tyre would allow some more degree of bounce (which yields a softer landing but does not compromise take-offs/taxi), instead of messing with the (beautiful + light) U/C...

My 0.02.

Tiger Moth + OS GF40
 

I have just started construction of the plane.


Basically, this post will concern the installation of the OS GF40 4-stroke gas engine. I decided on the engine the minute I laid eyes on it, I was hoping for something of that size/quality/principle to come along for a number of years.. It is somewhat large for the model (allegedly) but the extra weight will help on balancing (plus a 20x6-prop will not yield a lot of speed anyhow).


Plus, the Tiger Moth lends itself nicely to 4-stroke sound (putt-putting around like a kite at idle).


Step#1: Measure twice - cut once
Initial measurements showed that the engine would fit without firewall shortening, but using the shortest OS stand-offs (12.7mm)!
However:
(i) A substantial relief cut would have to be made for the carb.
(ii) H9 made the mistake(?) of pre-installing the blind nuts in the firewall - meaning that if the bolt pattern of the engine of choice is close to the pre-installed pattern there will be some major clashing...


So, the decision was made to remove the factory firewall and shorten the engine box accordingly so as to clear the carb (avoid a large cut-out). Measurements showed that removing about 36mm from the engine box would be just the ticket. A set of long OS stand-offs (2") would be required to bring the engine position back to original distance from the front bulkhead.


Before any cuts were made:
(i) Care was taken to transfer the mark of the thrustline to the sides of the box, so that this datum is not lost after removal of the originally marked piece.
(ii) The in-built thrust angles of the original construction were measured. Right-thrust was about 2 degrees and down-thrust of about 1 degree. Note: these angles were measured using the top of the engine box as a 0-datum - the already-covered plane does not lend itself to determining a clear datum/thrust line. The stab seat was then measured at +1.5degrees.


The sides of the box were intentionally left longer, to allow reinforcement with triangle stock later on - much like other posters have done earlier-on in this thread.

STEP #2: Dummy Firewall


After the old firewall was removed, the opening was measured and a carton template was fitted.
The measurements were then passed onto a new firewall out of 8mm aircraft ply.

STEP #3: New Firewall Alignment, Gluing and Engine Mounting


The new firewall was given new thrust angles:
2.5 degrees right-thrust and 2 degrees down. The additional downthrust was decided due to the ballooning effect reported here.
(Decalage modifications will also follow later on in an effort to alleviate the effect as much as possible). Combined with the +1.5 degrees of the stab seat, the total effective downthrust will now be 3.5 degrees.


The offset mouting position of the engine + stand-offs was calculated anew to make sure the new thrust angles plus the modified mounting plane would yield a centered prop hub at the front of the cowl.


Caveat: due to the backwards translation of the new firewall position, combined with the new increased thrust angles, the new offset mounting position of the top right stand-off of the engine ended-up too close to the firewall corner.

The following solution has been worked out:
- Just shave 4mm off the existing stand-off and interject a 4mm-thick dural piece to offset the stand-off mounting point slightly.
- Engine stand-offs were OS 2" original (Part #.74003580). One of the 4 was shaved on a lathe (2mm each side) for true parallel facing.
- The dural piece was cut off with a Dremel from an old chassis spare part of my HPI Baja 1/5-scale RC Gas car.

Result: The engine is small enough to allow complete in-cowl installation with a bonus of scale location of the exhaust outlet! One needs to use an OS 80degree exhaust elbow to achieve this.